Dental Implant Complications










771
31
Dental Implant Complications
RANDOLPH R. RESNIK
I
n implant dentistry today, most procedures are completed free
of complications. However, complications do occur and may
have devastating, long-lasting eects for the patient and the
clinician. Ideally the clinician should have a strong understanding
of surgical and prosthetic implant principles, which minimizes the
possibility of complications. However, even if the clinician follows
the most strict and predictable protocols, unexpected situations
may occur. erefore this chapter provides a comprehensive sum-
mary of the etiology, prevention, and management of possible
complications resulting from the treatment planning, intra-opera-
tive, post-operative, and maintenance situations.
Intraoperative Complications
Malpositioned Initial Osteotomy Site
In performing the initial osteotomy for a dental implant, in some
cases the initial implant position may not be placed in the ideal
location. e osteotomy may need to be repositioned to allow for
ideal placement. e use of a Lindemann bur (i.e., side-cutting
ssure bur) is ideal for the repositioning of an osteotomy because
of its side-cutting capabilities. Lindemann burs allow for easy and
ecient positional change with minimal trauma to the bone.
Once the initial osteotomy is prepared, it is assessed for proper
position with a direction indicator. If nonideal placement occurs, the
osteotomy site may need to be “stretched” or repositioned to a more
ideal location.
Prevention
Surgical templates or implant-positioning devices for ideal implant
positioning should be used to prevent the improper placement of the
initial osteotomy. A pilot surgical guide (i.e., guide that allows only
for the drilling of the rst pilot drill) can be used for the clinician to
obtain the accurate mesial-distal and buccal-lingual position of the
osteotomy site. is is especially useful for decreasing the possibility
of malpositioning for clinicians who are early on their learning cure.
Treatment
e use of conventional drills (non-side-cutting) is dicult to hori-
zontally reposition an osteotomy site because of the end-cutting
capabilities of the burs. e use of a side-cutting Lindemann bur will
allow for repositioning to a new, corrected site. It is imperative the
new osteotomy position should be deepened so that subsequent end-
cutting drills will not reposition back into the original osteotomy site.
However, when using the Lindemann bur, always use copi-
ous amounts of saline because this bur will generate a signi-
cant amount of trauma and heat to the bone
1
(Fig. 31.1).
Facial Dehiscence After Implant Placement
After implant placement, it is not uncommon to have facial
plate dehiscence on the buccal aspect of the implant, usually
in the crestal area. Because bone resorbs from the facial to lin-
gual, in some cases after implant placement, less than 2.0 mm
of facial bone is present. A minimum of 2.0 mm of bone is
recommended to maintain ideal hard and soft tissue surround-
ing the implant. If the implant is allowed to heal with a known
facial dehiscence, the implant will be more susceptible to peri-
implant disease and increased implant morbidity.
Ridges that are compromised (i.e., Division B, C, or D) should be
modied to obtain a Division A bone (e.g., >7 mm width and >10
mm of bone height) before osteotomy initiation. is may be accom-
plished by either osteoplasty or lateral bone augmentation. After
implant placement, a minimum of 2.0 mm of facial bone should be
present over the implant or the compromised facial area should be
grafted.
Treatment
After implant placement, if there exists less than 2.0 mm of bone
on the facial aspect of the ridge, the site may be grafted with autog-
enous bone (ideally). e autogenous bone is most easily obtained
from bone fragments gathered from the utes of the surgical drills
during the osteotomy preparation. e consistency of this bone
allows for ease of packing, and the graft will have less chance of
migrating. Ideally, the autogenous bone should be red or white
colored as this signies live, viable bone. If the bone fragments are
black or brown, the bone should be discarded as it is most likely
necrotic. Allograft bone is not the most ideal bone to graft in this
area as it tends to migrate easily after placement and is an added
expense (Fig. 31.2).
Loss of Facial Plate When Placing an Implant
When placing implants in bone that is compromised in width
(i.e., Division B bone), it is not uncommon to fracture or lose the
facial plate of the supporting bone. is leads to a compromise in
the healing of the implant and the longevity of the implant and
nal prosthesis.

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PART VI Implant Surgery
Prevention
Ideally the width of bone needs to exceed 7.0 mm for placement
of a 4.0-mm diameter implant. When compromised width of
bone exists, the trauma of the osteotomy or the placement of the
implant may fracture or “pop o” the buccal plate. is is most
likely the result of the buccal plate being thinner than the lingual
plate, which results in the facial plate being more fragile and
susceptible to fracture (Fig. 31.3).
e available bone before implant placement should be eval-
uated via a cone beam computed tomography (CBCT) exami-
nation. If nonideal width of bone is present, site development,
including grafting, is indicated to obtain a Division A bone. e
osteotomy preparation should be in one plane, and care should be
exercised not to deviate from the original angulation. If Division
B bone is present, ridge augmentation is recommended to achieve
a Division A ridge before implant placement.
Treatment
After implant placement, if a fracture or loss of the buccal plate
exists, treatment will depend on the extent of the decit.
Loss of Entire Buccal Plate. If the entire buccal plate is lost
or if mobility of the implant exists, the ideal treatment should
include removing the implant, followed by grafting the site. After
sucient healing occurs, implant placement may be completed.
Partial Buccal Plate Still Intact. If no mobility of the implant
is present and the facial plate is partially intact, the facial area can
be grafted, ideally with autogenous bone from the osteotomy site
(e.g., bone from the surgical drill).
A BC
Fig. . Facial Dehiscence. (A) Crestal bone is missing after implant placement, which often occurs
because of buccal and lingual crestal height discrepancies. (B) Autogenous bone fragments within the bur
flutes. (C) Grafting after implant placement.
Fig. . Implant placement with partial loss of the buccal plate. Note
the fractures present in the host bone.
A
C
B
Fig. . Repositioning Osteotomy Site. (A) Side-cutting Lindeman bur. (B) Use of a Lindeman bur to
reposition the osteotomy should always deepen the new osteotomy site because this will prevent sub-
sequent burs from falling into the original site. (C) Clinical image of repositioning osteotomy more distal.

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CHAPTER 31 Dental Implant Complications
Overheating the Bone
One of the most common complications that has been associ-
ated with early implant failure and bone loss is overheating of
the bone during the osteotomy preparation. is is usually the
result of osteotomy preparation in dense bone with a nonideal
surgical osteotomy protocol. e Misch osteotomy preparation
protocol has been developed to minimize heat generation in
D1 and D2 bone density types. Bone tissue has been shown
to be very susceptible to thermal related injuries, with studies
showing the temperature threshold to be 47 °C for tissue sur-
vival when drilling is maintained for more than 60 seconds. If
heat generation is higher than this limit, then osseointegration
is in question because of the resulting necrosis of the surround-
ing bone cells.
2
In addition, resultant hyperemia, brosis,
osteocytic degeneration and increased osteoclast activity
may occur which may lead to a necrotic zone around the
implant.
3
Prevention
Intermediate Burs. In addition to the surgical protocol,
multiple intermediate drills may be used in the drilling pro-
tocol (See Chapter 27). A decrease in the heat and trauma
generated is seen when gradual increases in drill diameter are
used. is technique reduces the amount of pressure and heat
transmitted to the bone, especially in the presence of dense and
thick cortical bone.
Copious Amounts of Saline. Together with external irri-
gation from the surgical drills, increased irrigation may be
obtained by using internal irrigation (through the surgical bur)
or with supplemental irrigation via a syringe. In addition, the
use of chilled saline allows for a signicant reduction of heat
generation.
Bone Dance. e bone-dancing technique was introduced by
Misch in 1988 to reduce the amount of heat generation. When
preparing the osteotomy, small increments of bone are removed
by using an up-and-down motion of the drill. is will allow
increased irrigation into the osteotomy, along with removing bone
fragments, which decreases frictional heat.
Use of Sharp, New Drills. Drills that are dull will increase
heat generation, causing the possibility of overheating the
bone. Surgical drills should be replaced approximately every
20 to 30 autoclave cycles; however, this is highly dependent
on past use.
Drill Speed. Sharawy etal.
4
have shown the drill speed in hard,
dense bone (e.g. D1 and D2 bone types) should be approximately
2000 to 2500 rpm. Osteotomy preparation at higher speeds with
sharp drills elicits less risk for osseous damage and a decreased
amount of devitalized zone adjacent to the implant. Yeniyol etal.
5
have shown that drilling at very slow speeds results in a higher
degree of bone fragmentation. However, in poorer bone density,
lower speed (e.g., 1000 rpm) may be used with little concern for
overheating the bone.
Surgical Templates. Surgical templates often result in over-
heating of the bone because of the inability of saline to enter the
osteotomy because of the minimal space between the guide tubes
in the template and the drill size. Ideally the template should be
modied to open up the facial aspect of the template so supple-
mental irrigation may be used (Fig. 31.4).
Treatment
If known excess heat generation occurs during implant placement,
ideally the implant should be removed, regional acceleratory phe-
nomenon (RAP) initiated, and the site grafted for future implant
placement. If bone width is available after sucient RAP is com-
pleted, a wider implant may be placed.
A B
Fig. . Overheating of the osteotomy site often occurs when using a surgical template. (A) With most
surgical templates, minimal irrigation enters the osteotomy site. (B) Ideally supplemental irrigation can be
used to decrease heat generation. Note the modification of the template which allows for external irrigation.

774
PART VI Implant Surgery
Implant Pressure Necrosis
When placing implants in bone with thick cortical compo-
nents (i.e., D1 and D2 bone), possible early implant failure
may occur from pressure necrosis. Numerous studies have
shown that the overcompression of the crestal bone is a con-
tributing factor in peri-implant disease and implant failure.
6
It is suggested that excessive tightening of the implant creates
compression forces within the crestal bone around the implant.
is may impair the microcirculation and lead to bone
resorption.
Pressure necrosis from implant placement may increase the
devital zone of bone around the implant, or even cause short-term
neurosensory impairment when the implant site is in the vicin-
ity of the mandibular canal. is most often occurs where there
exists a cortical component of bone in the crestal region (D1–D2
bone). If a crestal bone drill is not used or surgical steps to alleviate
the internal stresses are not completed, excess stress will be gener-
ated on insertion of the implant, which will lead to “die-back” or
a devitalized zone (Fig. 31.5).
Prevention
Torque. e implant should not be “tightened” into the oste-
otomy with excessive torque pressure. A torque value of 35 N-cm
is considered safe with most threaded implant designs. If excessive
pressure is present, the implant should be unscrewed 3 to 4 mm
and then reinserted.
Crestal Bone Bur. Because most implants have a wider crest
module (wider diameter of the neck of the implant in comparison
with the implant body), greater stress can be concentrated upon
placement in D1 and D2 types of bone. To decrease crestal pres-
sure, a crestal bone bur can be used to minimize the stress at the
ridge crest.
Use of Insertion Wrench. To decrease the crestal stress, the implant
may be inserted with a hand ratchet to depth, then unthreaded 3
to 4 mm, and then reinserted to ideal depth. By unscrewing the
implant 3 to 4 mm, the bone is given time to “creep,” which on
reinsertion, will have less force at the crestal region.
Treatment
Ideally the thickness of crestal bone and bone quality type should
be ascertained before implant osteotomy preparation. is may be
determined via a CBCT radiographic examination.
If a large cortical component of bone is present and the implant
placed is known to contain excess pressure, the implant should be
removed and the crestal bone modied. e implant then should
be reinserted at a lower insertion torque.
Injury to Adjacent Teeth
Damaging adjacent natural teeth during dental implant place-
ment may lead to adverse eects on adjacent tooth structures
and can result in dental implant failure or adjacent tooth loss.
e injury to the root structure of adjacent teeth may be direct
(i.e., damage to tooth by the drill or implant) or indirect (i.e.,
thermal damage from the osteotomy process). e direct trauma
may result in bone loss, natural tooth or implant loss, infection,
internal or external resorption, loss of tooth vitality, or pros-
thetic failure.
Trauma to adjacent teeth may occur upon the placement of
dental implants because of poor surgical technique including
improper angulation, implant sites with insucient available
space or bone quantity, or placement of implants with an incorrect
diameter. Dilacerated roots and excessive tilting of natural teeth in
the mesiodistal direction may impinge on the intended implant
space and prevent ideal placement. In addition, available space
discrepancies often exist between the coronal space and the api-
cal space. Studies of orthodontic mini-implants placed in contact
with teeth (<1.0 mm) have been shown to cause root resorption.
However, if the implant is removed in a timely fashion, cementum
repair may occur.
7
Prevention
e location of adjacent teeth to the implant site should be evalu-
ated before implant placement. is is most accurately deter-
mined by evaluating CBCT images, usually in the axial plane.
Accurate spacing is easily determined by measuring the intertooth
distance. e angulation should always be evaluated after the ini-
tial osteotomy with a direction indicator (i.e., radiograph with
known diameter and length guide pin in osteotomy) to assess
proper positioning and angulation. CBCT surgical templates may
be used to avoid damaging adjacent root surfaces. Ideally a mini-
mum of 1.5 mm of space between the implant and root surface is
recommended.
Treatment
Perioperative. If after placement of the dental implant, it
appears the implant is too close (<1.5 mm) from the periodontal
ligament or tooth structure, ideally it should be removed and
repositioned. If the implant is removed and another is inserted,
care should be exercised to verify adequate primary stability. If
primary stability is not obtained, then an implant with a larger
diameter or length may be inserted. If that is not feasible, then
the osteotomy site should be grafted and implant placement
delayed.
Postoperative/Post-healing. If the implant has been previously
placed and is asymptomatic and not encroaching on the periodon-
tal ligament/tooth structure, strict monitoring should be completed
on a regular basis, with vitality testing of the adjacent teeth. If the
adjacent tooth is sensitive to thermal stimulation or percussion, the
implant should be removed immediately (Fig. 31.6).
Fig. . Overheating the bone from improper surgical drilling protocol;
note the lack of bleeding from the osteotomy site.

775
CHAPTER 31 Dental Implant Complications
Swallowing/Aspiration of Implant Components
Because of the nature of dental implant procedures, the aspira-
tion or ingestion of dental components or materials may occur.
Accidental inhalation of dental instruments (drills, burs, direction
indicators, root tips, crowns, etc.) can result in many complica-
tions, including life-threatening situations. Because of the small
size of abutments, screws, drivers, and other implant components,
a signicant risk for the implant clinician exists. is may occur
during any dental implant procedure, including the surgical and
prosthetic phases.
ere is usually two possibilities: the patient may swallow the
foreign object into the stomach or aspirate the foreign object into
the lungs.
Swallow: If the object is swallowed, usually the patient will
be asymptomatic. However, depending on the shape and
size of the object, it may need to be removed because of
the complication of blockage within the gastrointestinal
system.
Aspiration: e object may be aspirated into the lungs, in
which case the patient will usually be symptomatic. e pa-
tient will exhibit signs of coughing, wheezing, hoarseness,
choking, stridor, or cyanosis. e patient will often com-
plain of pain and discomfort.
Prevention
Various techniques are available for the implant clinician to pre-
vent aspiration or swallowing of a foreign object. ere is no one
technique that will guarantee this complication will be avoided;
however, extreme caution should always be exercised.
Techniques to prevent swallowing or aspiration include:
• Flossligaturestoallimplantcomponents.
• Useofspecialprostheticinstruments(e.g.,EasyReachWrench;
Salvin Dental).
• Usethroatpacks(4×4gauze)orpharyngealscreens.
• Utilizehigh-vacuumsuction.
• Usecurvedhemostatsforretrievalofobjects.
Treatment
When swallowing or aspiration of implant components occurs,
the clinician must act proactively to avoid complications and
medicolegal issues. First, if an instrument is lost in the mouth,
the patient should be instructed not to sit straight up because
this will ensure the swallowing or aspiration of the instrument.
e patient should turn to the side and attempt to “cough” the
instrument up. If the instrument is lost, symptoms usually will
determine whether aspiration into the lungs or swallowing into
the stomach has occurred. If the instrument has been swallowed
into the stomach, usually the patient will exhibit no symptoms.
If the patient has aspirated the instrument, this will most likely
be accompanied with coughing, wheezing, pain, and cyanosis.
is may be life-threatening and should be treated accordingly as
a medical emergency. In all swallowing/aspiration situations the
patient should be referred immediately to his or her physician or
emergency room for a chest x-ray. If the instrument has been aspi-
rated, it will usually be located in the right bronchus because the
right main bronchus has a more acute angle than the left. Rigid
bronchoscopy is usually used for the removal of the instrument
under general anesthesia (Fig. 31.7).
Air Emphysema
Because of the attachment apparatus dierence between implants
and teeth, air extruded into the sulcular area around implants may
lead to air emphysema. Subcutaneous emphysema is a condition
in which air is introduced into the subcutaneous or fascial spaces.
e two most common ways for this to occur is the use of an air-
driven handpiece or an air-water syringe in which air is forced into
the sulcular area. Symptoms will include swelling that increases
over time, with a “crackling” feeling with pain. Crepitus to palpa-
tion will conrm the diagnosis of air emphysema. e patient will
usually be apprehensive, with a feeling of diculty in breathing.
Subcutaneous air emphysema can lead to many devastating
complicationsduringandafterdentalimplantsurgery.Earlyrec-
ognition and management of this condition is crucial to preventing
A B
Fig. . (A) Implant placement too close to a tooth root; implant should be removed and reinserted in
a more ideal position. (B) Implant that was placed many years ago should be closely monitored clinically
and radiographically.

776
PART VI Implant Surgery
progression of the problem. As the air accumulates subcutane-
ously, dissection occurs along the connective tissue that joins the
adjacent muscle planes. Via the fascial spaces, air from the oral
cavity may extend into the mediastinum space, where it can com-
municate with parapharyngeal and retropharyngeal spaces, which
leads to airway compromise. From the retropharyngeal space, air
may lead into the pleural space and pericardium, which could
result in heart and lung failure.
Prevention
When placing implants, modifying abutments in the oral cavity,
or removing bone around an implant body, an electric handpiece
should always be used (i.e., never use an air-driven handpiece). In
addition, air-water syringes should never be used to place air into
the sulcular area parallel to the long axis of the implant.
Treatment
Usually symptoms arise immediately; however, cases have been
described in the literature that have occurred minutes to hours
after a procedure. Patients with signicant emphysema should
be monitored closely before discharge, for respiratory or cardiac
distress. Treatment should include supportive therapy with heat
and analgesics. Antibiotic therapy should always be administered
because infection may result from bacteria being induced into the
fascial spaces, with resultant cellulitis or necrotizing fascitis. Reso-
lution usually occurs in 4 to 7 days, with minimal morbidity. In
isolated cases, exploratory surgery, emergency tracheotomy, and
the placement of chest tubes have been reported (Fig. 31.8).
8
Electric Handpiece Burns
Electrichandpieces,themostcommontypeofhandpieceusedin
implant dentistry today, have a tendency to overheat, which may
result in signicant soft tissue complications. In 2007 and 2010,
theU.S.FoodandDrugAdministration(FDA)releasedwarn-
ings to health professionals concerning possible serious burns
related to electric dental handpieces. e FDA has requested
manufacturers to decrease these issues by design modication,
overheating alarms, warning labels, and clinician training to
avoid overheating.
Because electric handpieces have insulated housings, the clini-
cian may not be aware of the extent of the heat generated in the
handpiece. Compounding the problem is that the patient may be
anesthetized and unaware of the thermal injury. Injuries have been
reported ranging from rst- to third-degree burns and may require
reconstructivesurgery. Unlikeconventional air-driven handpieces
that decrease eciency when overworked, electric handpieces will
maintain higher eciency, thus generating a greater amount of heat.
Primary
bronchi
Secondary
bronchi
Te rtiary
bronchi
Bronchioles
Cardiac
notch
Trachea
Larynx
A
B
CD
Fig. . Aspiration of Foreign Bodies. (A) Pulmonary system anatomy. (B) Implant driver lodged in the
right bronchus. (C) Floss should be tied to all implant components to minimize aspiration. (D) Use a 4 × 4
throat pack; never use a 2 × 2 pack because the patient can easily swallow it.

777
CHAPTER 31 Dental Implant Complications
Prevention
Awareness is most crucial for avoiding this complication. e clini-
cian should be conscious of the possibility of the handpiece overheat-
ing, take frequent breaks during treatment, and check continuously
fortheimplantmotorbecominghotduringtreatment.Electrichand-
pieces should have routine maintenance according to the manufac-
turersrecommendations.Usuallythestraight1:1handpieceshavea
greater incidence than the 16:1 or 20:1 reduction handpieces.
Treatment
If a burn occurs, treatment will vary depending on the severity. Treat-
ments range from over-the-counter ointment to a physician referral.
For severe burns, systemic antibiotics are warranted. If the burn does
not penetrate the vermillion border, healing will usually result with-
out a defect.
Monopolar Electrosurgery Units
Monopolar electrosurgical units are a common soft tissue modal-
ity used in dentistry today. However, in implant dentistry, when
these units are used around dental implants, signicant complica-
tions may arise. Monopolar electrocautery should never be used in
the proximity of a dental implant or implant prosthesis.
Electrosurgeryisdenedasthecontrolledpassageofhigh-
frequency waveforms, or currents, for the purpose of altering
the surrounding soft tissue. e action of monopolar electro-
cautery is cutting the tissue by means of an advancing spark
with a grounded patient. is results in sparking, current
spread, and thermal damage in the tissues because of the gen-
eration of heat.
Prevention
In implant dentistry, monopolar electrosurgery units are contrain-
dicated. e monopolar electrodes should not contact an implant
or electrical shock osteoradionecrosis and possible implant loss
may result. However, bipolar electrosurgical units have been
shown to be eective around dental implants. Bipolar electrocau-
tery uses molecular resonance with a sine-wave current that pre-
vents sparking and thermal damage. ese types of units may be
used continuously around implants because they produce progres-
sive coagulation rather than a single high-output discharge, thus
creating no spark.
9
Treatment
Treatment is usually palliative in nature because electrosurgery
damage is usually irreversible in nature (Fig. 31.9).
A
B
C
Fig. . (A) Facial air emphysema. (B) Air-water syringes should never be directed along the long axis of
the implant. (C) Proper air-water syringe positioning, perpendicular to the long-axis of the dental implant.
ABC
Fig. . (A) Implant site that was treated with an electrosurgery unit. (B) Implant loss and bone necrosis.
(C) Resultant large bony defect.

778
PART VI Implant Surgery
Salivary Gland Injury
e sublingual gland may be injured when an implant is poorly posi-
tioned in the posterior mandible, which may cause the formation
of a ranula. Ranulas are dened as an accumulation of extravasated
salivary secretions that form pseudocysts in the submandibular area.
When the ranulas form above the mylohyoid muscle, they appear as
a translucent, bluish swelling in the sublingual space. Most ranulas
are visible on a clinical examination and are considered “plunging”
when they extend inferiorly from the sublingual space into the neck
area. Ranulas are usually not xed, and they are rarely painful unless
they become secondarily infected. In some cases they develop into
larger lesions and may compromise the airway.
e proximity of the sublingual gland to the lingual cortical plate
of the mandible makes it susceptible to injury. Trauma usually occurs
from improper angulation during dental implant surgery, which per-
forates the lingual cortex and causes damage to the sublingual gland.
In addition, the gland may be injured during aggressive reection and
retraction when working in the sublingual area.
Prevention
To prevent damage to the salivary glands, ideal preoperative treat-
ment planning, good surgical technique, proper implant angula-
tion, and careful retraction will avoid these complications.
In addition, the anatomy of the sublingual area must be under-
stood. e sublingual gland is positioned adjacent to the lingual
cortex and seated below the mylohyoid muscle.
e submandibular duct is positioned inferior and medial
to the sublingual gland. e lingual nerve will cross the sub-
mandibular duct from medial to lateral and then cross back
at the rst premolar area, where it branches into the tongue
musculature.
Treatment
Treatment should include referral to an oral and maxillofacial sur-
geon, which usually involves the complete removal of the sublin-
gual gland. In some cases, where the ranulas are very small and
asymptomatic, no surgery may be indicated or marsupialization to
reestablish connection with the oral cavity (Fig. 31.10).
10
Bleeding-Related Complications
Prevention/Treatment of Bleeding
e ideal management of intraoperative hemorrhage is preven-
tion. Although the clinician should be capable of handling poten-
tial bleeding complications, the best course of action is avoidance,
which is aided by taking the appropriate preventive measures. A
preoperative assessment of the patient is mandatory, including a
thorough preoperative patient history, and medical consultation
when indicated. e clinician also should be familiar with manag-
ing patients receiving anticoagulants and those who have bleeding
issues, should use meticulous intraoperative surgical technique,
and should provide appropriate postoperative instructions, care,
and follow-up. Patients need to be instructed on the importance
of compliance with prescribed medication and proper postopera-
tive instructions and care.
Incision/Reflection of Tissue
e dental implant clinician must carefully plan the location of
incisions with respect to surgical anatomy to maintain hemostasis
and minimize bleeding. Ideally incisions should always be made
over host bone when possible. is will allow for pressure to be
applied over bone in the event of uncontrolled bleeding. e ap
design should incorporate release incisions so that excessive pres-
sure and stretching is reduced to decrease possible tearing of the
tissue and resultant blood vessel trauma.
Reection and elevation of the mucosa and periosteum should
be carefully completed with full-thickness and atraumatic reec-
tion. Split-thickness aps should be avoided to minimize potential
bleeding sites. Anatomic areas containing vital structures, which
may be highly vascular, should be carefully evaluated and avoided
if possible (Fig. 31.11).
A B
Fig. . Salivary Gland Damage. (A) Anatomic depiction of the sublingual gland (red) and subman-
dibular gland (green). (B) Implant perforation of the lingual plate may result in gland damage.

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CHAPTER 31 Dental Implant Complications
Anatomy/Anatomic Variants
Strategic planning of potential implant sites is extremely impor-
tant, with a thorough understanding of anatomic structures and
variants with the use of CBCT. e lack of distortion of the
CBCT images allows the clinician to better plan surgical sites,
while maintaining relatively safe zones from anatomic structures.
Mandibular Anterior: Intraosseous Vessels
Median Vascular Canal. On occasion, in the mandibular
midline, copious bleeding may be present (e.g., C position, even
though no bone perforation has occurred). Bilateral sublingual
arteries enter through the lingual foramen within the lingual plate
below the genial tubercles in the mandible. As this anastomo-
sis transverses within the anterior mandible, the canal is termed
the median vascular canal. Bleeding in this area may be signi-
cant; however, it is not associated with any type of neurosensory
impairment. e presence and size of the sublingual anastomosis
and the median vascular canal is most commonly seen on a cross-
sectional or axial image of a CBCT scan. If a large anastomosis
is present, the position of the planned osteotomy may need to be
modied.
Management. If signicant bleeding occurs after implant oste-
otomy in the midline, a direction indicator or surgical bur can be
placed in the osteotomy site to apply pressure. If the osteotomy is
completed, an implant may also be introduced into the site, which
will compress the walls of bone, thus slowing the bleeding process
(Fig. 31.12). In most cases intraosseous bleeding is more easily
controlled in comparison with soft tissue hemorrhage.
Inferior Alveolar Artery. e inferior alveolar artery is a
branch of the maxillary artery, one of the two terminal branches
of the external carotid. Before entering the mandibular foramen,
it gives o the mylohyoid artery. In approximately the rst molar
region, it divides into the mental and incisal branches. e mental
branch exits the mental foramen and supplies the chin and lower
lip, where it eventually will anastomose with the submental and
inferior labial arteries. e exact location of the inferior alveolar
artery is easily determined via a CBCT evaluation in the pan-
oramic or sagittal views.
Management. Normally the inferior alveolar artery is located
superiorly to the inferior alveolar nerve within the bony mandib-
ular canal. Drilling or placing an implant into the inferior alveo-
lar canal may predispose to signicant bleeding. Hemorrhage
may be controlled by placement of an implant or direction
indicator short of the canal. A 2.0-mm safety zone between the
implant and canal should be adhered to. If bleeding does occur,
follow-up postoperative care is essential because hematoma for-
mation within the canal may lead to a neurosensory impairment.
is condition should be monitored because it may progress to
respiratory depression via a dissecting hematoma in the oor of
the mouth (Fig. 31.13).
Incisive Artery. e incisive artery is the second terminal
branch of the inferior alveolar artery, which is a branch of the
maxillary artery. e incisal branch continues anteriorly after sup-
plying the mandibular rst molar area, where it innervates the
incisor teeth and anastomoses with the contralateral incisal artery.
In rare cases the incisive canal is large, lending to greater bleed-
ing during osteotomy preparation or bone-grafting procedures.
11
e exact location of the incisive canal is easily determined via a
CBCT evaluation in the panoramic or sagittal views.
AB
Fig. . (A) Ideal incision location and full-thickness reflection will reduce bleeding with atraumatic
reflection of the tissue. (B) Split-thickness flap, which results in increased bleeding and tissue trauma.
Fig. . Median Vascular Canal. In the mandibular midline, the radio-
lucent canal that houses the right and left sublingual anastomosis.

780
PART VI Implant Surgery
Management. Bleeding complications can occur when implants
are placed into the mandibular incisive canal, which contains the
incisive artery. If bleeding does occur during placement of the
implant, a direction indicator, surgical bur, or implant can be
placed into the osteotomy to apply pressure (Fig. 31.14).
Mandibular Anterior: Extraosseous Vessels
e anterior mandible is usually known as a safe area for implant
placement, but in certain situations it may present with a signicant
undercut on the lingual aspect between the foramina. Life-threaten-
ing hemorrhage has been reported when a drill perforates the lin-
gual plate of the sublingual region of the mandible and traumatizes
a sublingual or submental artery, especially in the canine region.
12,13
If perforation of the lingual cortical plate is associated with
arterial bleeding, it is critical to identify its origin and treat aggres-
sively. e origin of bleeding in the oor of the anterior region of
the mouth may be from the lingual artery, facial artery, or one of
its branches. e submental artery originates from the facial artery
and courses along the inferior border of the mandible. e sublin-
gual artery, a branch of the lingual artery, runs along the inferior
border of the mandible and terminates in the midline. Perforation
in this area may lead to bleeding, causing an expanding ecchymo-
sis (sublingual hematoma) and compromising the airway.
Sublingual Artery (Lingual Artery). e lingual artery is a
branch of the external carotid artery between the superior thyroid
and facial arteries. e lingual artery courses medially to the greater
horn of the hyoid bone and crosses inferiorly and facially around
the hypoglossal nerve. It then transverses deep to the digastric
and stylohyoid muscles, and courses between the hyoglossus and
genioglossus muscles. ere exist four main branches of the lingual
artery: the suprahyoid, dorsal lingual, deep lingual, and sublingual.
Of clinical signicance to oral implantology is the sublingual
artery, which supplies the sublingual salivary gland, mylohyoid and
surrounding muscles, and the mucous membranes and gingiva of
the mandible. A distal branch runs medially in the anterior lingual
mandibular gingiva and anastomoses with the contralateral artery.
An additional branch connects with the submental artery under the
mylohyoid muscle.
14
e lingual artery will anastomose throughout
the tongue area, with more anastomoses occurring anteriorly.
15
Submental Artery (Facial Artery). e most important branch
of the facial artery associated with oral implantology is the sub-
mental branch, which is the largest of the branches of the facial
artery. e submental branch exits the submandibular gland and
proceeds anteriorly on the surface of the mylohyoid muscle, just
inferior to the body of the mandible. e submental branch termi-
nates as an anastomosis with the sublingual branch of the lingual
artery and the mylohyoid branch of the inferior alveolar artery.
14
Studies have shown that the oor of the mouth and lingual
gingiva are supplied approximately 53% by the submental artery
and the remaining by the sublingual artery.
16
Perforation of the
lingual cortical plate may result in trauma to the submental artery.
Treatment should include immediate repositioning of the patient
in an upright position followed by the application of bimanual
pressure. is should be immediately applied, followed by airway
management and emergency protocol.
Bleeding from the submental artery may be decreased by
applying nger pressure over the lower border of the mandible.
Doppler ultrasonography studies have shown this to reduce the
arterial blood by 25% to 50% at the oral commissure level and
33% to 50% at the inferior border of the nares.
17
Prevention. Clinical and radiographic evaluation should be
completed to ascertain the amount of available bone and osse-
ous angulation in the anterior mandible. e length of implants
should be carefully evaluated because bicortical stabilization
(which may lead to perforation of the lingual plate) is no lon-
ger advocated for implant success. is is most important in the
mandibular canine position as the arteries are close to the lingual
cortical plate. In addition, care should be exercised in elevation of
the lingual ap and manipulation of the lingual tissue.
Clinical Signicance. Bleeding into the sublingual and sub-
maxillary spaces will cause elevation of the tongue and oor of the
mouth. Bleeding in these spaces will proceed to airway obstruction
because the anterior extension of the hematoma is limited by the
supercial layers of the cervical fascia.
18
e signs and symptoms
of sublingual swelling include immediate or delayed (up to 4–8
hours after surgery) elevation of the oor of the mouth, protrusion
of the tongue, profuse intraoral bleeding, diculty in swallow-
ing, and respiratory depression. e submandibular swelling may
dislocate the trachea to the contralateral side and compromise the
airway.
19
In addition, pulsatile hematomas (pseudoaneurysms) of
the lingual artery may result from the injury (Fig. 31.15).
20
Fig. . Incisive Canal Vessels. The incisive canal is the radiolucent
canal extending anterior from the mental foramen and mandibular canal.
Implants placed into this area may cause increased bleeding.
Fig. . Implant placement into the mandibular canal, which may
result in excessive bleeding from the inferior alveolar artery.

781
CHAPTER 31 Dental Implant Complications
Management. Immediate bimanual pressure should be applied
tothebleedingareaifthelocationcanbedetermined.A4×4
gauze may be used to apply the bimanual compression downward
from the oor of the mouth (lingual surface of the mandible) and
in an upward direction from the submental skin area. e patient
should be repositioned from a supine to an upright position.
Young forceps may be used to pull the tongue outward, which
will slow the bleeding. Airway obstruction should be of vital con-
cern because this may lead to a life-threatening situation. If any
clinical signs of airway obstruction exist (e.g., dyspnea, dyspha-
gia, wheezing, stridor, cyanosis), emergency intervention should
be summoned immediately. Ligation of the bleeding vessel is the
ideal treatment to control the hemorrhage. is may be dicult
in an oce setting because of the location and surgical access
of the bleeding vessel. To obtain denitive control of sublingual
artery bleeding, surgical intervention with selective ligation of the
branches, along with arterial embolization via interventional angi-
ography, is indicated (Fig. 31.16).
21
Perforating
Anastomosing Branches
of Right Sublingual and
Left Submental Arteries
Mucosal and
Cortical Branches of
Left Sublingual
Artery
Submental
Artery
Cortical Branch of
Right Submental
Artery
A
B C
Fig. . (A) Sublingual and submental artery anatomy in the floor of the mouth. (B) Perforating lingual
plate, which may cause sublingual bleeding. (C) To slow the bleeding, bimanual pressure with a 4 × 4
gauze on the lingual surface of the mandible and extraoral pressure on the inferior mandible. (From Loukas
M, Kinsella CR Jr, Kapos T, et al: Anatomical variation in arterial supply of the mandible with special regard
to implant placement. Int J Oral Maxillofac Surg 37(4):367–371, 2008.)

782
PART VI Implant Surgery
Mandibular Posterior: Extraosseous Vessels
Posterior Lingual Undercut. In the mandibular posterior area
a lingual undercut may be problematic and dicult to manage. In
this area, perforation of the lingual plate can occur easily, thereby
causing bleeding episodes, with an origin that may be dicult
to locate. Life-threatening situations may result from sublingual
bleeding. Violation of this area may cause infection or constant
irritation from the extruded implant in the soft tissue. If the perfo-
ration were to occur above the mylohyoid muscle, damage to the
lingual nerve could result in a neurosensory impairment.
Prevention. A clinical examination should always be carried
out to determine whether an osseous undercut exists. is may
be conrmed with a CBCT examination because cross-sectional
images are an eective way of observing lingual undercuts. In
addition, angulation and positioning must be continuously veri-
ed to prevent inadvertent perforation. Studies have shown that
lingual undercuts occur in approximately 66% of the population,
with a mean undercut of 2.4 mm.
22
Accurate measurements must
be made to prevent overpreparation of the osteotomy site in the
posterior mandible.
A
B
C
D
Fig. . Sublingual Hematoma. (A) Four implants placed flapless in the anterior mandible. (B) Resul-
tant sublingual hematoma with airway compromise. (C) Axial computed tomography images showing
extent of hematoma (blue arrows) with airway compromise. Note perforation of lingual cortical plate (red
arrow). (D) Young forceps may be used to pull tongue out to decrease the bleeding and helps maintain
airway until medical assistance arrives. (From Limongelli L, Tempesta A, Crincoli V, etal: Massive lingual
and sublingual haematoma following postextractive flapless implant placement in the anterior mandible.
Case Rep Dent. 2015;2015:839098.)

783
CHAPTER 31 Dental Implant Complications
Accurate visualization of this area is most easily completed
with a CBCT examination. Osteotomy angulation should
always be carefully evaluated because improper drilling angu-
lation may lead to perforations. In addition, hourglass man-
dibles, which have been shown to have an incidence rate of
approximately 4%, should always be concerning because per-
foration will occur.
23
In addition, clinical palpation of the ridge during osteotomy
preparation will minimize perforations and decrease complica-
tions. During osteotomy preparation, handpiece control must be
maintained to minimize inadvertent lingual plate perforation.
Management. If sublingual posterior bleeding (submental or
sublingual arteries) occurs, the patient should be repositioned in
an upright position and bimanual pressure should be applied to
the area of bleeding. If the airway is compromised, immediate
emergency assistance should be summoned (Fig. 31.17).
Buccal Artery. A popular donor site for autogenous grafting
is the lateral ramus area in the posterior mandible. When making
the incision lateral to the retromolar pad, a common blood vessel
to damage is the buccal artery. e buccal artery is a branch of the
maxillary artery and will most likely cause a signicant bleeding
episode. is artery runs obliquely between the internal pterygoid
and the insertion of the temporalis on the outer surface of the
buccinator.
Prevention. In most cases damage to the buccal artery is impos-
sible to avoid. Incision and reection will usually encompass the
area of buccal artery location. When performing surgery in this
area, a curved hemostat should always be available for immediate
access to clamp the vessel.
Management. A curved Kelly hemostat should be used to con-
trol the bleeding. It should be left in place for 3 to 5 minutes until
clotting is complete. If bleeding persists, a ligature may be placed
with Vicryl suture material (Fig. 31.18).
Maxilla: Lateral Wall/Nasal Bleeding
Signicant bleeding from the lateral approach sinus elevation
surgery is rare; however, when it occurs, it has the potential to
be troublesome. ree main arterial vessels should be of concern
with the lateral approach sinus augmentation. Because of the
intraosseous and extraosseous anastomoses that are formed by the
infraorbital and posterior superior alveolar arteries, intraoperative
bleeding complications of the lateral wall may occur. In some cases
this bleeding may be signicant.
Extraosseous Anastomosis. e soft tissue vertical release inci-
sions of the facial ap in a resorbed maxilla may sever the extraos-
seous anastomoses during lateral wall osteotomy preparation for
sinus graft surgery. e extraosseous anastomosis on average is
located 23 mm from the crest of the dentate ridge; however, in
the resorbed maxilla, it may be within 10 mm of the crest. When
this artery is severed, signicant bleeding has been observed. ese
vessels originate from the maxillary artery and have no bony land-
mark to compress the vessel. Vertical release incisions in the soft
tissue should be kept to a minimum height, with delicate reec-
tion of the periosteum. Hemostats are usually dicult to place
on the facial ap to arrest the bleeding. Signicant pressure at the
AB
Fig. . Mandibular Posterior Undercut. (A) Three-dimensional image depicting the posterior under-
cut. (B) When an undercut is present, limited available height is present for implant placement. This will
often lead to a crown/implant ratio issue.
Fig. . Buccal Artery. The buccal artery is often traumatized when
making incisions in the retromolar area.

784
PART VI Implant Surgery
posterior border of the maxilla and elevation of the head to reduce
the blood pressure to the vessels usually slows the bleeding. e
elevation of the head may reduce nasal mucosal blood ow by
38%.
24
Intraosseous Anastomosis. e vertical component of the
lateral access wall for the sinus graft often severs the intraosse-
ous anastomoses of the posterior alveolar artery and infraorbital
artery, which is on average approximately 15 to 20 mm from the
crest of a dentate ridge. Methods to limit this bleeding, which is
far less of a risk, include cauterization with the use of a handpiece
and diamond bur without water, electrocautery, or pressure on a
surgical sponge while the head is elevated. In some cases a second
window is made distal to the bleeding area source for access to
ligate (Fig. 31.19).
Posterior Lateral Nasal Artery. e third artery that
implant surgeons should be cautious of is the posterior lat-
eral nasal artery (Fig. 31.20). is artery is a branch of the
sphenopalatine artery, which is located within the medial wall
of the antrum. As it courses anteriorly, it anastomoses with
terminal branches of the facial artery and ethmoidal arteries.
A signicant bleeding complication may arise if this vessel is
severed during elevation of the membrane o the thin medial
wall.
If the excessive bleeding occurs while the medial wall is ele-
vated, the sinus may be packed with hemostatic agents, followed
bypackingwithlarge4×4-inchsurgicalspongesandelevationof
the head. Once the bleeding is arrested, the sponges are removed,
the layered graft materials may be inserted, and the procedure
completed.
Epistaxis(activebleedingfromthenose)aftersinusgraftsur-
gery is rather common. is may occur with or without a known
membraneperforation.Usuallyepistaxisislimitedtotherst24
hours after surgery, and the patient should always be warned of
this potential complication.
A CB
Fig. . Intraosseous Anastomosis. (A) Cross-sectional image showing radiolucent notch on the
lateral wall of the sinus. (B) Intraosseous notch (red arrow). (C) Intraosseous anastomosis pulsating bleed
(white arrows).
AB
Fig. . (A) Posterior lateral nasal artery (red line) in close approximation to the lateral wall of the nasal
cavity (medial wall of maxillary sinus). (B) Nasal bleed during sinus augmentation procedure.

785
CHAPTER 31 Dental Implant Complications
If bleeding should occur through the nose, there exist numer-
ous techniques to obtain hemostasis. Placing a cotton roll, coated
with petroleum jelly with dental oss tied to one end, within the
nares may obtund nose bleeding after the surgery. After 5 minutes
the dental oss is gently pulled and the cotton roll removed. e
head is also elevated, and ice is applied to the bridge of the nose.
If bleeding cannot be controlled, reentry into the graft site and
endoscopicligationby an ENT (ear,nose, and throat)surgeon
may be required.
If the orbital wall of the sinus is perforated or if an opening
into the nares is already present from a previous event (i.e., pre-
vious sinus surgery), the sinus curette may enter the nares and
initiate bleeding. e arteries involved in this site are composed of
branches of the sphenopalatine and descending palliative arteries,
which are branches of the internal maxillary artery. e posterior
half of the inferior turbinate has a venous network, the Woodru
plexus, which is highly vascular. A cotton roll with silver nitrate or
lidocaine with 1:50,000 epinephrine is also eective in obtaining
hemostasis.
Postoperative Bleeding Control
Patient Education
It is imperative that patients understand that minor oozing
may persist for up to 24 hours after dental implant surgery. If
the patient is taking anticoagulants, this may persist for up to
48 hours. e patient should be instructed on the use of pres-
sure dressings, and special care should be taken to minimize any
trauma to the surgical site (e.g., eating, pulling on lip to see surgi-
cal site). e patient should avoid rinsing the mouth vigorously.
All postoperative instructions should be reviewed with the patient
and given in writing before surgery.
Patients should be instructed to limit their activities for a mini-
mum of 24 hours, depending on the extent of the surgery. e
head should be elevated as much as possible during the daytime
hours, and the use of two pillows (i.e., elevate head) during sleep-
ing will reduce secondary bleeding episodes.
Postoperative hemorrhage in anticoagulated patients may lead
to signicant issues. Studies have shown bleeding episodes in anti-
coagulant patients will most likely occur within 6 days of the sur-
gery.
25
In patients who have exhibited signicant bleeding during
surgery, hemorrhagic shock, although rare, should be evaluated. If
the patient displays any signs or symptoms of shock (e.g., tachy-
cardia, hypotension, lethargy, disorientation, cold/clammy skin),
immediate medical assistance should be summoned. Treatment
would include intravenous uid replacement to replenish the
intravascular volume and restore tissue perfusion. Finally, caution
should be exercised on the postoperative use of medications that
may increase bleeding. A comprehensive review of the patient’s
medications should be completed to determine whether any drug
interactions may exist that would increase bleeding. Agents that
interfere with platelet function should be avoided for routine
analgesia (e.g., nonsteroidal antiinammatory drugs [NSAIDs],
aspirin) unless the benet outweighs the increased risk for bleed-
ing. e routine perioperative use of aspirin should usually be
avoided because of an increased risk for bleeding and lack of ben-
et. However, if these medications are administered for a separate
indication under the recommendation of a physician (e.g., recent
stroke, acute coronary syndromes, implanted coronary stent),
they should be continued.
Techniques to Decrease and Control Bleeding
e need to control gross bleeding is paramount for successful
surgery because insidious and continuous loss of blood from
arteries, veins, or capillaries can become signicant if bleeding is
not controlled. Dental implant clinicians have numerous options
for maintaining hemostasis, which include mechanical, thermal,
pharmacologic, and topical agents.
Mechanical Methods
e most common primary mechanical method to control bleed-
ing is to apply direct pressure or compression on the bleeding site,
along with repositioning the patient. Secondary mechanical meth-
ods include suturing, clamping the blood vessel with hemostats,
and ligating the bleeding vessel with suture material.
Positional Changes. When signicant bleeding occurs, main-
taining the patient in a supine position is not recommended
because of increased bleeding (head below the heart). Hydrostatic
pressure occurs within the vascular system because of the weight
of the blood vessels and is dependent on gravity. e pressure is
decreased in any vessel above the heart and increased in blood
vessels below the heart. Studies have shown that in an upright
position, the average pressure at the level of the heart is 100 mm
Hg. Vessels in the head and neck averaged 49 and 186 mm Hg,
respectively, at the foot level.
26
Repositioning the patient to an
upright position (head above the heart) will not stop the bleed-
ing; however, it will signicantly decrease the hemorrhage (studies
have shown a decrease up to 38%).
27
Direct Pressure. If signicant intraoperative bleeding occurs,
the ideal treatment should involve immediate application of pres-
sure to the surgical site. Pressure or compression directly on the
blood vessel will allow for platelet aggregation and initiation of
the coagulation cascade. Pressure may be applied manually or by
the patient biting forcefully on a gauze dressing. Pressure should
be maintained for at least 3 to 5 minutes to allow the formation of
a blood clot. Caution should be exercised not to remove the gauze
too early because this may dislodge the clot.
Ideally3×3or4×4gauzeshouldbeusedbecause2×2gauze
may be accidentally aspirated. In primary bleeding, pressure is the
simplest and fastest method to control bleeding before the use of
hemostatic measures.
Suturing. Suturing plays a signicant role not only in obtain-
ing primary closure for ideal healing but also for maintaining
hemostasis (direct versus indirect). Direct placement of a suture
(ligation) is used when there is access to a deep bleeding ves-
sel. e suture is placed by entering the tissue at least 4 mm
from the bleeding vessel, 3 mm below the vessel, and 4 mm
exiting the tissue. is will ligate or occlude the vessel as long as
it is placed proximal to the bleeding area. A gure-eight suture
technique is ideally used. Indirect suture placement is used to
retract the tissue and minimize bleeding via pressure from the
accumulated tissue. is is most often used as tie-backs when
reecting an edentulous mandible (cuspid to molar bilaterally).
And lastly, good suturing technique is paramount for prevent-
ing reactionary bleeding after surgery. Ideally interrupted or
mattress sutures should be placed in conjunction with continu-
ous sutures to maintain closure. A suture material that exhibits
high tensile strength is recommended, such as polyglycolic acid
(e.g., Vicryl). e interim prosthesis should be modied to have
no direct pressure on the wound site, as this may dislodge the
sutures (Fig. 31.21).

786
PART VI Implant Surgery
Clamped Vessel With Hemostat Forceps. When local mea-
sures are not successful in controlling bleeding, a hemostat may be
usedtoclampthebloodvessel.UsuallyacurvedKellyhemostat
may be used to clamp the vessel to control the bleeding via two
mechanisms:
1. e rst mechanism is occluding the vessel and damaging the
blood vessels wall to stimulate clotting. is clamping pressure
should be maintained for approximately 2 to 3 minutes, which
will usually allow for hemostasis. However, this method may
be unreliable because the clot may become dislodged and post-
operative bleeding may occur after removal of the hemostat.
2. A more successful technique in controlling bleeding is to use
ne-pointed hemostats (Kelly hemostats) and ligate the bleed-
ing vessel with suture material. e vessel should be clamped
to obtain immediate hemostasis, with the tip of the hemostat
extending beyond the vessel. A clamped vessel may be ligated
with suture material such as an absorbable suture with high
tensile strength (e.g., Vicryl). A tie should be placed around
the hemostat, extending to the vessel. e hemostats are then
removed, and two additional throws are made with the suture.
Usually bleeding from vessels of 2 mm or greater diameter
should be ligated. Direct ligation of the bleeding blood ves-
sel is usually the most eective technique in stopping arterial
blood ow. However, exposure and identication of the bleed-
ing vessel may sometimes be extremely dicult. In addition,
the bleeding may occur from multiple capillaries, which may
result in dicult hemostasis.
Electrocautery. Electrocauterization,developedinthe1930s,
has been one of the most common hemostatic techniques because
ofitslowcost,accessibility,easeofuse,andeectiveness.Electro-
cautery is the process of destroying tissue using heat conduction,
with a probe that is heated by an electric current. Dierent proce-
dures may be completed with the use of high radiofrequency alter-
nating current for cutting, coagulating, and vaporizing tissues.
Electrocauteryismosteectiveonsmallvesselsandmaybeused
in two modes: monopolar and bipolar (Fig. 31.22).
Monopolar electrosurgery delivers current using dierent types
of waveforms (i.e., modes). e coagulation mode uses an inter-
rupted waveform, which generates heat, thereby coagulating a
cell, a phenomenon also termed fulguration. e cutting mode is
low energy, which produces a cutting eect to vaporize tissue with
minimal hemostasis. e blend mode simultaneously cuts tissue
and coagulates bleeding. is technique is often dicult to use in
implant surgery because access and a relatively dry eld is needed
to cauterize the vessel. A dry eld is needed for the eective electri-
cal current to pass through the tissues. A high-speed plastic, not
metal, suction tip should be used to maintain a dry eld.
Buzzing the Hemostat (Electrocautery + Hemostat Ligation).
Usually on larger vessels the combination of a clamped vessel
(with curved hemostat) and electrocautery will allow for the cau-
terizing of the blood vessel, thus stopping blood ow in the vessel.
e protocol is as follows:
1. Usethelowestpossiblesettingtoachievethedesiredeect.
2. Use the CUT mode, not the COAG mode. COAG has a
higher peak-to-peak voltage and is more prone to alternate
(small) current pathways.
A
B
Fig. . Electrocautery. (A) Monopolar electrocautery, which uses
current to establish hemostasis. A ball electrode is the most common to
be used; however, access is sometimes difficult. (B) A battery-operated
disposable cautery unit that does not use current, however generates heat
to ligate the blood vessel.
A
B
Fig. . Suturing. (A) Direct ligation with figure-eight suturing tech-
nique. (B) Indirect tie-back of the mandibular lingual tissue from cus-
pid-molar contralaterally, which decreases bleeding, allows for ease of
retraction, and prevents tissue trauma.

787
CHAPTER 31 Dental Implant Complications
3. After clamping the vessel, touch the active electrode to the
hemostat closer to the patient (below the hand holding the
hemostat) and then activate the electrode. is minimizes
sparking and the subsequent demodulation of current, while
encouraging a path of least resistance.
NOTE: Care should be exercised because the implant clini-
cian may receive burns or be shocked even when wearing pro-
tective gloves. When the surgeon clamps a bleeding vessel and
the electrode is touched to the hemostat, the tissue between the
clamped hemostat is coagulated. e “buzzing” may cause high-
voltage breakdown of the surgeons glove, leading to a burn. To
minimize this possibility, the surgeons glove should be changed, if
wet, because hydrated gloves show a lower resistance. In addition,
the electrode should be placed in contact with the hemostat before
activation of the electrosurgical current, to minimize the produc-
tion of a spark (Fig. 31.23).
Lasers. Lasers, which are gaining popularity as a tool in den-
tal surgery, may also be used to achieve hemostasis. Laser is an
acronym for “light amplication by stimulated emission of radia-
tion,” which produces laser light energy. Laser energy delivered
to an area of bleeding may be reected, scattered, transmitted, or
absorbed. e extent of the tissue reaction depends on the laser
wavelength, power settings, spot size, and length of contact time
with the bleeding area. Lasers have been shown to be a safe or
useful modality in treating dental surgery patients with bleeding
disorders.
28
Pharmacologic Techniques
Although pharmacologic techniques may be used in implant den-
tistry to control bleeding, the success of maintaining hemostasis is
questionable, with varying results.
Epinephrine. Epinephrinemaybeusedtoenhancehemostasis
in combination with local anesthesia (e.g., 2% Lidocaine 100,000,
1/50,000 epinephrine). When locally placed, epinephrine will
reduce bleeding, slow the absorption of the local anesthetic, and
prolong the anesthetic and analgesic eect. e hemostatic prop-
erties are related to platelet aggregation, which leads to a decrease
in the adrenoreceptors within the vessel walls, thus producing
vasoconstriction. However, rebound hyperemia may result post-
operatively, which will increase bleeding. Various studies have
shown that topical application of a 1/100,000 concentration of
epinephrine creates vasoconstriction and controls hemostasis with
sinus graft procedures, with no appreciable changes in systemic
hemodynamics.
29
Tranexamic Acid Solution. Tranexamic acid 4.8% is an anti-
brinolytic oral rinse that facilitates clot formation by inhibiting
the activation of plasminogen to plasmin. Plasmin prevents the
clotting process from initiating brinolysis. Tranexamic acid solu-
tion may be used as a mouthwash postoperatively and has been
shown to enhance clotting in patients with coagulopathies or anti-
coagulant therapy. Sindet-Pedersen and Ramstrom
30
showed a sig-
nicant reduction in postoperative bleeding with a 10-mL rinse,
four times a day for 7 days postoperatively. Choi etal.
31
reported
a signicant decrease in bleeding during maxillary surgery after
a bolus of tranexamic acid was given preoperatively (Fig. 31.24).
Topical Hemostatic Agents. Absorbable topical hemostatic
agents are used when conventional methods of hemostasis are
ineective. ese agents may be placed directly into the bleed-
ing site to decrease bleeding during the procedure or during the
postoperative interval. ey work either mechanically or by aug-
menting the coagulation cascade. e topical hemostatic agents
have the added benet of minimizing the possibility of systemic
blood clots, which are drawbacks of systemic hemostatic agents.
ere are two types: active and passive (Table31.1).
Active Hemostatic Agents
Thrombin. Active topical hemostatic agents have biologic
activity that induces clotting at the end of the coagulation cas-
cade. Most active agents used in dental implant surgery con-
tain the coagulant thrombin. rombin is a naturally derived
Hemostat
Blood vessel
B
C
Fig. . (A–C) “Buzzing the hemostat” usually used for larger-vessel ligation (arterial). The vessel is
clamped with the hemostat, and the electrocautery unit is placed on CUT mode and lightly touches the
hemostat. A spark will usually result (arrow). Before its use, supplemental oxygen (nasal cannula) should
be discontinued to prevent a patient airway fire.

788
PART VI Implant Surgery
Active and Passive Hemostatic Agents
COMMON HEMOSTATIC AGENTS
Type Product Advantages Disadvantages
Collagen OraTape, OraPlug (Salvin), CollaTape,
CollaPlug (Zimmer)
Inexpensive; resorbs in 10–14 days; highly
absorbent to many times its own weight
None
Microcellular collagen Avitene (Davol), Helitene (Integra),
Instat (Ethicon)
Good application for large surfaces; supe-
rior hemostasis to gelatin and cellulose
Difficult to handle; expensive
Gelatin GelFoam (Baxter), Surgiform (Ethicon) Swelling after application results in tam-
ponade effect; neutral pH
May cause tissue/neural damage due to
compression from swelling; possible
dislodgement from bleeding site
Cellulose Surgicel (Ethicon), Blood Stop (Salvin),
Oxycel (Becton Dickinson), ActCel
(Coreva Health Sciences)
Easy to handle; low pH provides antimi-
crobial coverage; expands three to four
times its original size and converts to
a gel
Possible foreign body reaction; low pH
may lead to possible postoperative
irritation; needs to be removed
Thrombin Thrombin-JMI Bovine (Pfizer),
Evithrom-human (Ethicon), Reco-
throm-recombinant (ZymoGenetics)
Can be added to collagen products, good
for small-vessel bleeding
Bovine has been shown to be immuno-
genic; leads to severe coagulopathy
Thrombin + gelatin FloSeal (Baxter) Very good for arterial bleeding areas
because it acts as an adhesive
Can result in significant swelling from
the compression; can cause neural
disturbance
Fibrin sealant Tisseel (Baxter)
Evicel (Ethicon)
Good for larger bleeding areas because it
acts as an adhesive
Expensive; preparation time
Kaolinite QuikClot (Z-Medica) Kaolin is a natural occurring mineral Limited use in dental surgery; needs to
be poured into wound; exothermic
reaction causes heat
Synthetic bone hemo-
static agents
Bone wax
Ostene (Ceremed)
Ostene is soluble; it dissolves in 48 hours
and is not metabolized, with a low bac-
terial adhesion and infection rate
Bone wax is insoluble; must be removed
or will cause inflammation and a
foreign body giant cell reaction; should
not be used in implant dentistry
TABLE
31.1
A
B
Fig. . Tranexamic Acid Injection. (A) Injection solution (Auromedics, East Windsor, N.J.). (B) Inject-
able tranexamic acid placed under bleeding flap.

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77131Dental Implant ComplicationsRANDOLPH R. RESNIKIn implant dentistry today, most procedures are completed free of complications. However, complications do occur and may have devastating, long-lasting eects for the patient and the clinician. Ideally the clinician should have a strong understanding of surgical and prosthetic implant principles, which minimizes the possibility of complications. However, even if the clinician follows the most strict and predictable protocols, unexpected situations may occur. erefore this chapter provides a comprehensive sum-mary of the etiology, prevention, and management of possible complications resulting from the treatment planning, intra-opera-tive, post-operative, and maintenance situations.Intraoperative ComplicationsMalpositioned Initial Osteotomy SiteIn performing the initial osteotomy for a dental implant, in some cases the initial implant position may not be placed in the ideal location. e osteotomy may need to be repositioned to allow for ideal placement. e use of a Lindemann bur (i.e., side-cutting ssure bur) is ideal for the repositioning of an osteotomy because of its side-cutting capabilities. Lindemann burs allow for easy and ecient positional change with minimal trauma to the bone.Once the initial osteotomy is prepared, it is assessed for proper position with a direction indicator. If nonideal placement occurs, the osteotomy site may need to be “stretched” or repositioned to a more ideal location.PreventionSurgical templates or implant-positioning devices for ideal implant positioning should be used to prevent the improper placement of the initial osteotomy. A pilot surgical guide (i.e., guide that allows only for the drilling of the rst pilot drill) can be used for the clinician to obtain the accurate mesial-distal and buccal-lingual position of the osteotomy site. is is especially useful for decreasing the possibility of malpositioning for clinicians who are early on their learning cure.Treatmente use of conventional drills (non-side-cutting) is dicult to hori-zontally reposition an osteotomy site because of the end-cutting capabilities of the burs. e use of a side-cutting Lindemann bur will allow for repositioning to a new, corrected site. It is imperative the new osteotomy position should be deepened so that subsequent end-cutting drills will not reposition back into the original osteotomy site.However, when using the Lindemann bur, always use copi-ous amounts of saline because this bur will generate a signi-cant amount of trauma and heat to the bone1 (Fig. 31.1). Facial Dehiscence After Implant PlacementAfter implant placement, it is not uncommon to have facial plate dehiscence on the buccal aspect of the implant, usually in the crestal area. Because bone resorbs from the facial to lin-gual, in some cases after implant placement, less than 2.0 mm of facial bone is present. A minimum of 2.0 mm of bone is recommended to maintain ideal hard and soft tissue surround-ing the implant. If the implant is allowed to heal with a known facial dehiscence, the implant will be more susceptible to peri-implant disease and increased implant morbidity.Ridges that are compromised (i.e., Division B, C, or D) should be modied to obtain a Division A bone (e.g., >7 mm width and >10 mm of bone height) before osteotomy initiation. is may be accom-plished by either osteoplasty or lateral bone augmentation. After implant placement, a minimum of 2.0 mm of facial bone should be present over the implant or the compromised facial area should be grafted.TreatmentAfter implant placement, if there exists less than 2.0 mm of bone on the facial aspect of the ridge, the site may be grafted with autog-enous bone (ideally). e autogenous bone is most easily obtained from bone fragments gathered from the utes of the surgical drills during the osteotomy preparation. e consistency of this bone allows for ease of packing, and the graft will have less chance of migrating. Ideally, the autogenous bone should be red or white colored as this signies live, viable bone. If the bone fragments are black or brown, the bone should be discarded as it is most likely necrotic. Allograft bone is not the most ideal bone to graft in this area as it tends to migrate easily after placement and is an added expense (Fig. 31.2). Loss of Facial Plate When Placing an ImplantWhen placing implants in bone that is compromised in width (i.e., Division B bone), it is not uncommon to fracture or lose the facial plate of the supporting bone. is leads to a compromise in the healing of the implant and the longevity of the implant and nal prosthesis. 772PART VI Implant SurgeryPreventionIdeally the width of bone needs to exceed 7.0 mm for placement of a 4.0-mm diameter implant. When compromised width of bone exists, the trauma of the osteotomy or the placement of the implant may fracture or “pop o” the buccal plate. is is most likely the result of the buccal plate being thinner than the lingual plate, which results in the facial plate being more fragile and susceptible to fracture (Fig. 31.3).e available bone before implant placement should be eval-uated via a cone beam computed tomography (CBCT) exami-nation. If nonideal width of bone is present, site development, including grafting, is indicated to obtain a Division A bone. e osteotomy preparation should be in one plane, and care should be exercised not to deviate from the original angulation. If Division B bone is present, ridge augmentation is recommended to achieve a Division A ridge before implant placement.TreatmentAfter implant placement, if a fracture or loss of the buccal plate exists, treatment will depend on the extent of the decit.Loss of Entire Buccal Plate. If the entire buccal plate is lost or if mobility of the implant exists, the ideal treatment should include removing the implant, followed by grafting the site. After sucient healing occurs, implant placement may be completed. Partial Buccal Plate Still Intact. If no mobility of the implant is present and the facial plate is partially intact, the facial area can be grafted, ideally with autogenous bone from the osteotomy site (e.g., bone from the surgical drill). A BC• Fig. . Facial Dehiscence. (A) Crestal bone is missing after implant placement, which often occurs because of buccal and lingual crestal height discrepancies. (B) Autogenous bone fragments within the bur flutes. (C) Grafting after implant placement.• Fig. . Implant placement with partial loss of the buccal plate. Note the fractures present in the host bone.ACB• Fig. . Repositioning Osteotomy Site. (A) Side-cutting Lindeman bur. (B) Use of a Lindeman bur to reposition the osteotomy should always deepen the new osteotomy site because this will prevent sub-sequent burs from falling into the original site. (C) Clinical image of repositioning osteotomy more distal. 773CHAPTER 31 Dental Implant ComplicationsOverheating the BoneOne of the most common complications that has been associ-ated with early implant failure and bone loss is overheating of the bone during the osteotomy preparation. is is usually the result of osteotomy preparation in dense bone with a nonideal surgical osteotomy protocol. e Misch osteotomy preparation protocol has been developed to minimize heat generation in D1 and D2 bone density types. Bone tissue has been shown to be very susceptible to thermal related injuries, with studies showing the temperature threshold to be 47 °C for tissue sur-vival when drilling is maintained for more than 60 seconds. If heat generation is higher than this limit, then osseointegration is in question because of the resulting necrosis of the surround-ing bone cells.2 In addition, resultant hyperemia, brosis, osteocytic degeneration and increased osteoclast activity may occur which may lead to a necrotic zone around the implant.3PreventionIntermediate Burs. In addition to the surgical protocol, multiple intermediate drills may be used in the drilling pro-tocol (See Chapter 27). A decrease in the heat and trauma generated is seen when gradual increases in drill diameter are used. is technique reduces the amount of pressure and heat transmitted to the bone, especially in the presence of dense and thick cortical bone. Copious Amounts of Saline. Together with external irri-gation from the surgical drills, increased irrigation may be obtained by using internal irrigation (through the surgical bur) or with supplemental irrigation via a syringe. In addition, the use of chilled saline allows for a signicant reduction of heat generation. Bone Dance. e bone-dancing technique was introduced by Misch in 1988 to reduce the amount of heat generation. When preparing the osteotomy, small increments of bone are removed by using an up-and-down motion of the drill. is will allow increased irrigation into the osteotomy, along with removing bone fragments, which decreases frictional heat. Use of Sharp, New Drills. Drills that are dull will increase heat generation, causing the possibility of overheating the bone. Surgical drills should be replaced approximately every 20 to 30 autoclave cycles; however, this is highly dependent on past use. Drill Speed. Sharawy etal.4 have shown the drill speed in hard, dense bone (e.g. D1 and D2 bone types) should be approximately 2000 to 2500 rpm. Osteotomy preparation at higher speeds with sharp drills elicits less risk for osseous damage and a decreased amount of devitalized zone adjacent to the implant. Yeniyol etal.5 have shown that drilling at very slow speeds results in a higher degree of bone fragmentation. However, in poorer bone density, lower speed (e.g., ∼1000 rpm) may be used with little concern for overheating the bone. Surgical Templates. Surgical templates often result in over-heating of the bone because of the inability of saline to enter the osteotomy because of the minimal space between the guide tubes in the template and the drill size. Ideally the template should be modied to open up the facial aspect of the template so supple-mental irrigation may be used (Fig. 31.4). TreatmentIf known excess heat generation occurs during implant placement, ideally the implant should be removed, regional acceleratory phe-nomenon (RAP) initiated, and the site grafted for future implant placement. If bone width is available after sucient RAP is com-pleted, a wider implant may be placed. A B• Fig. . Overheating of the osteotomy site often occurs when using a surgical template. (A) With most surgical templates, minimal irrigation enters the osteotomy site. (B) Ideally supplemental irrigation can be used to decrease heat generation. Note the modification of the template which allows for external irrigation. 774PART VI Implant SurgeryImplant Pressure NecrosisWhen placing implants in bone with thick cortical compo-nents (i.e., D1 and D2 bone), possible early implant failure may occur from pressure necrosis. Numerous studies have shown that the overcompression of the crestal bone is a con-tributing factor in peri-implant disease and implant failure.6 It is suggested that excessive tightening of the implant creates compression forces within the crestal bone around the implant. is may impair the microcirculation and lead to bone resorption.Pressure necrosis from implant placement may increase the devital zone of bone around the implant, or even cause short-term neurosensory impairment when the implant site is in the vicin-ity of the mandibular canal. is most often occurs where there exists a cortical component of bone in the crestal region (∼D1–D2 bone). If a crestal bone drill is not used or surgical steps to alleviate the internal stresses are not completed, excess stress will be gener-ated on insertion of the implant, which will lead to “die-back” or a devitalized zone (Fig. 31.5).PreventionTorque. e implant should not be “tightened” into the oste-otomy with excessive torque pressure. A torque value of 35 N-cm is considered safe with most threaded implant designs. If excessive pressure is present, the implant should be unscrewed 3 to 4 mm and then reinserted. Crestal Bone Bur. Because most implants have a wider crest module (wider diameter of the neck of the implant in comparison with the implant body), greater stress can be concentrated upon placement in D1 and D2 types of bone. To decrease crestal pres-sure, a crestal bone bur can be used to minimize the stress at the ridge crest.Use of Insertion Wrench. To decrease the crestal stress, the implant may be inserted with a hand ratchet to depth, then unthreaded 3 to 4 mm, and then reinserted to ideal depth. By unscrewing the implant 3 to 4 mm, the bone is given time to “creep,” which on reinsertion, will have less force at the crestal region. TreatmentIdeally the thickness of crestal bone and bone quality type should be ascertained before implant osteotomy preparation. is may be determined via a CBCT radiographic examination.If a large cortical component of bone is present and the implant placed is known to contain excess pressure, the implant should be removed and the crestal bone modied. e implant then should be reinserted at a lower insertion torque. Injury to Adjacent TeethDamaging adjacent natural teeth during dental implant place-ment may lead to adverse eects on adjacent tooth structures and can result in dental implant failure or adjacent tooth loss. e injury to the root structure of adjacent teeth may be direct (i.e., damage to tooth by the drill or implant) or indirect (i.e., thermal damage from the osteotomy process). e direct trauma may result in bone loss, natural tooth or implant loss, infection, internal or external resorption, loss of tooth vitality, or pros-thetic failure.Trauma to adjacent teeth may occur upon the placement of dental implants because of poor surgical technique including improper angulation, implant sites with insucient available space or bone quantity, or placement of implants with an incorrect diameter. Dilacerated roots and excessive tilting of natural teeth in the mesiodistal direction may impinge on the intended implant space and prevent ideal placement. In addition, available space discrepancies often exist between the coronal space and the api-cal space. Studies of orthodontic mini-implants placed in contact with teeth (<1.0 mm) have been shown to cause root resorption. However, if the implant is removed in a timely fashion, cementum repair may occur.7Preventione location of adjacent teeth to the implant site should be evalu-ated before implant placement. is is most accurately deter-mined by evaluating CBCT images, usually in the axial plane. Accurate spacing is easily determined by measuring the intertooth distance. e angulation should always be evaluated after the ini-tial osteotomy with a direction indicator (i.e., radiograph with known diameter and length guide pin in osteotomy) to assess proper positioning and angulation. CBCT surgical templates may be used to avoid damaging adjacent root surfaces. Ideally a mini-mum of 1.5 mm of space between the implant and root surface is recommended. TreatmentPerioperative. If after placement of the dental implant, it appears the implant is too close (<1.5 mm) from the periodontal ligament or tooth structure, ideally it should be removed and repositioned. If the implant is removed and another is inserted, care should be exercised to verify adequate primary stability. If primary stability is not obtained, then an implant with a larger diameter or length may be inserted. If that is not feasible, then the osteotomy site should be grafted and implant placement delayed. Postoperative/Post-healing. If the implant has been previously placed and is asymptomatic and not encroaching on the periodon-tal ligament/tooth structure, strict monitoring should be completed on a regular basis, with vitality testing of the adjacent teeth. If the adjacent tooth is sensitive to thermal stimulation or percussion, the implant should be removed immediately (Fig. 31.6). • Fig. . Overheating the bone from improper surgical drilling protocol; note the lack of bleeding from the osteotomy site. 775CHAPTER 31 Dental Implant ComplicationsSwallowing/Aspiration of Implant ComponentsBecause of the nature of dental implant procedures, the aspira-tion or ingestion of dental components or materials may occur. Accidental inhalation of dental instruments (drills, burs, direction indicators, root tips, crowns, etc.) can result in many complica-tions, including life-threatening situations. Because of the small size of abutments, screws, drivers, and other implant components, a signicant risk for the implant clinician exists. is may occur during any dental implant procedure, including the surgical and prosthetic phases.ere is usually two possibilities: the patient may swallow the foreign object into the stomach or aspirate the foreign object into the lungs. Swallow: If the object is swallowed, usually the patient will be asymptomatic. However, depending on the shape and size of the object, it may need to be removed because of the complication of blockage within the gastrointestinal system.Aspiration: e object may be aspirated into the lungs, in which case the patient will usually be symptomatic. e pa-tient will exhibit signs of coughing, wheezing, hoarseness, choking, stridor, or cyanosis. e patient will often com-plain of pain and discomfort.PreventionVarious techniques are available for the implant clinician to pre-vent aspiration or swallowing of a foreign object. ere is no one technique that will guarantee this complication will be avoided; however, extreme caution should always be exercised.Techniques to prevent swallowing or aspiration include:• Flossligaturestoallimplantcomponents.• Useofspecialprostheticinstruments(e.g.,EasyReachWrench;Salvin Dental).• Usethroatpacks(4×4gauze)orpharyngealscreens.• Utilizehigh-vacuumsuction.• Usecurvedhemostatsforretrievalofobjects. TreatmentWhen swallowing or aspiration of implant components occurs, the clinician must act proactively to avoid complications and medicolegal issues. First, if an instrument is lost in the mouth, the patient should be instructed not to sit straight up because this will ensure the swallowing or aspiration of the instrument. e patient should turn to the side and attempt to “cough” the instrument up. If the instrument is lost, symptoms usually will determine whether aspiration into the lungs or swallowing into the stomach has occurred. If the instrument has been swallowed into the stomach, usually the patient will exhibit no symptoms. If the patient has aspirated the instrument, this will most likely be accompanied with coughing, wheezing, pain, and cyanosis. is may be life-threatening and should be treated accordingly as a medical emergency. In all swallowing/aspiration situations the patient should be referred immediately to his or her physician or emergency room for a chest x-ray. If the instrument has been aspi-rated, it will usually be located in the right bronchus because the right main bronchus has a more acute angle than the left. Rigid bronchoscopy is usually used for the removal of the instrument under general anesthesia (Fig. 31.7). Air EmphysemaBecause of the attachment apparatus dierence between implants and teeth, air extruded into the sulcular area around implants may lead to air emphysema. Subcutaneous emphysema is a condition in which air is introduced into the subcutaneous or fascial spaces. e two most common ways for this to occur is the use of an air-driven handpiece or an air-water syringe in which air is forced into the sulcular area. Symptoms will include swelling that increases over time, with a “crackling” feeling with pain. Crepitus to palpa-tion will conrm the diagnosis of air emphysema. e patient will usually be apprehensive, with a feeling of diculty in breathing.Subcutaneous air emphysema can lead to many devastating complicationsduringandafterdentalimplantsurgery.Earlyrec-ognition and management of this condition is crucial to preventing A B• Fig. . (A) Implant placement too close to a tooth root; implant should be removed and reinserted in a more ideal position. (B) Implant that was placed many years ago should be closely monitored clinically and radiographically. 776PART VI Implant Surgeryprogression of the problem. As the air accumulates subcutane-ously, dissection occurs along the connective tissue that joins the adjacent muscle planes. Via the fascial spaces, air from the oral cavity may extend into the mediastinum space, where it can com-municate with parapharyngeal and retropharyngeal spaces, which leads to airway compromise. From the retropharyngeal space, air may lead into the pleural space and pericardium, which could result in heart and lung failure.PreventionWhen placing implants, modifying abutments in the oral cavity, or removing bone around an implant body, an electric handpiece should always be used (i.e., never use an air-driven handpiece). In addition, air-water syringes should never be used to place air into the sulcular area parallel to the long axis of the implant. TreatmentUsually symptoms arise immediately; however, cases have beendescribed in the literature that have occurred minutes to hours after a procedure. Patients with signicant emphysema should be monitored closely before discharge, for respiratory or cardiac distress. Treatment should include supportive therapy with heat and analgesics. Antibiotic therapy should always be administered because infection may result from bacteria being induced into the fascial spaces, with resultant cellulitis or necrotizing fascitis. Reso-lution usually occurs in 4 to 7 days, with minimal morbidity. In isolated cases, exploratory surgery, emergency tracheotomy, and the placement of chest tubes have been reported (Fig. 31.8).8 Electric Handpiece BurnsElectrichandpieces,themostcommontypeofhandpieceusedinimplant dentistry today, have a tendency to overheat, which may result in signicant soft tissue complications. In 2007 and 2010, theU.S.FoodandDrugAdministration(FDA)releasedwarn-ings to health professionals concerning possible serious burns related to electric dental handpieces. e FDA has requested manufacturers to decrease these issues by design modication, overheating alarms, warning labels, and clinician training to avoid overheating.Because electric handpieces have insulated housings, the clini-cian may not be aware of the extent of the heat generated in the handpiece. Compounding the problem is that the patient may be anesthetized and unaware of the thermal injury. Injuries have been reported ranging from rst- to third-degree burns and may require reconstructivesurgery. Unlikeconventional air-driven handpiecesthat decrease eciency when overworked, electric handpieces will maintain higher eciency, thus generating a greater amount of heat. PrimarybronchiSecondarybronchiTe rtiarybronchiBronchiolesCardiacnotchTracheaLarynxABCD• Fig. . Aspiration of Foreign Bodies. (A) Pulmonary system anatomy. (B) Implant driver lodged in the right bronchus. (C) Floss should be tied to all implant components to minimize aspiration. (D) Use a 4 × 4 throat pack; never use a 2 × 2 pack because the patient can easily swallow it. 777CHAPTER 31 Dental Implant ComplicationsPreventionAwareness is most crucial for avoiding this complication. e clini-cian should be conscious of the possibility of the handpiece overheat-ing, take frequent breaks during treatment, and check continuously fortheimplantmotorbecominghotduringtreatment.Electrichand-pieces should have routine maintenance according to the manufac-turer’srecommendations.Usuallythestraight1:1handpieceshaveagreater incidence than the 16:1 or 20:1 reduction handpieces. TreatmentIf a burn occurs, treatment will vary depending on the severity. Treat-ments range from over-the-counter ointment to a physician referral. For severe burns, systemic antibiotics are warranted. If the burn does not penetrate the vermillion border, healing will usually result with-out a defect. Monopolar Electrosurgery UnitsMonopolar electrosurgical units are a common soft tissue modal-ity used in dentistry today. However, in implant dentistry, when these units are used around dental implants, signicant complica-tions may arise. Monopolar electrocautery should never be used in the proximity of a dental implant or implant prosthesis.Electrosurgeryisdenedasthecontrolledpassageofhigh-frequency waveforms, or currents, for the purpose of altering the surrounding soft tissue. e action of monopolar electro-cautery is cutting the tissue by means of an advancing spark with a grounded patient. is results in sparking, current spread, and thermal damage in the tissues because of the gen-eration of heat. PreventionIn implant dentistry, monopolar electrosurgery units are contrain-dicated. e monopolar electrodes should not contact an implant or electrical shock osteoradionecrosis and possible implant loss may result. However, bipolar electrosurgical units have been shown to be eective around dental implants. Bipolar electrocau-tery uses molecular resonance with a sine-wave current that pre-vents sparking and thermal damage. ese types of units may be used continuously around implants because they produce progres-sive coagulation rather than a single high-output discharge, thus creating no spark.9 TreatmentTreatment is usually palliative in nature because electrosurgery damage is usually irreversible in nature (Fig. 31.9). ABC• Fig. . (A) Facial air emphysema. (B) Air-water syringes should never be directed along the long axis of the implant. (C) Proper air-water syringe positioning, perpendicular to the long-axis of the dental implant.ABC• Fig. . (A) Implant site that was treated with an electrosurgery unit. (B) Implant loss and bone necrosis. (C) Resultant large bony defect. 778PART VI Implant SurgerySalivary Gland Injurye sublingual gland may be injured when an implant is poorly posi-tioned in the posterior mandible, which may cause the formation of a ranula. Ranulas are dened as an accumulation of extravasated salivary secretions that form pseudocysts in the submandibular area. When the ranulas form above the mylohyoid muscle, they appear as a translucent, bluish swelling in the sublingual space. Most ranulas are visible on a clinical examination and are considered “plunging” when they extend inferiorly from the sublingual space into the neck area. Ranulas are usually not xed, and they are rarely painful unless they become secondarily infected. In some cases they develop into larger lesions and may compromise the airway.e proximity of the sublingual gland to the lingual cortical plate of the mandible makes it susceptible to injury. Trauma usually occurs from improper angulation during dental implant surgery, which per-forates the lingual cortex and causes damage to the sublingual gland. In addition, the gland may be injured during aggressive reection and retraction when working in the sublingual area. PreventionTo prevent damage to the salivary glands, ideal preoperative treat-ment planning, good surgical technique, proper implant angula-tion, and careful retraction will avoid these complications.In addition, the anatomy of the sublingual area must be under-stood. e sublingual gland is positioned adjacent to the lingual cortex and seated below the mylohyoid muscle.e submandibular duct is positioned inferior and medial to the sublingual gland. e lingual nerve will cross the sub-mandibular duct from medial to lateral and then cross back at the rst premolar area, where it branches into the tongue musculature. TreatmentTreatment should include referral to an oral and maxillofacial sur-geon, which usually involves the complete removal of the sublin-gual gland. In some cases, where the ranulas are very small and asymptomatic, no surgery may be indicated or marsupialization to reestablish connection with the oral cavity (Fig. 31.10).10 Bleeding-Related ComplicationsPrevention/Treatment of Bleedinge ideal management of intraoperative hemorrhage is preven-tion. Although the clinician should be capable of handling poten-tial bleeding complications, the best course of action is avoidance, which is aided by taking the appropriate preventive measures. A preoperative assessment of the patient is mandatory, including a thorough preoperative patient history, and medical consultation when indicated. e clinician also should be familiar with manag-ing patients receiving anticoagulants and those who have bleeding issues, should use meticulous intraoperative surgical technique, and should provide appropriate postoperative instructions, care, and follow-up. Patients need to be instructed on the importance of compliance with prescribed medication and proper postopera-tive instructions and care. Incision/Reflection of Tissuee dental implant clinician must carefully plan the location of incisions with respect to surgical anatomy to maintain hemostasis and minimize bleeding. Ideally incisions should always be made over host bone when possible. is will allow for pressure to be applied over bone in the event of uncontrolled bleeding. e ap design should incorporate release incisions so that excessive pres-sure and stretching is reduced to decrease possible tearing of the tissue and resultant blood vessel trauma.Reection and elevation of the mucosa and periosteum should be carefully completed with full-thickness and atraumatic reec-tion. Split-thickness aps should be avoided to minimize potential bleeding sites. Anatomic areas containing vital structures, which may be highly vascular, should be carefully evaluated and avoided if possible (Fig. 31.11). A B• Fig. . Salivary Gland Damage. (A) Anatomic depiction of the sublingual gland (red) and subman-dibular gland (green). (B) Implant perforation of the lingual plate may result in gland damage. 779CHAPTER 31 Dental Implant ComplicationsAnatomy/Anatomic VariantsStrategic planning of potential implant sites is extremely impor-tant, with a thorough understanding of anatomic structures and variants with the use of CBCT. e lack of distortion of the CBCT images allows the clinician to better plan surgical sites, while maintaining relatively safe zones from anatomic structures.Mandibular Anterior: Intraosseous VesselsMedian Vascular Canal. On occasion, in the mandibular midline, copious bleeding may be present (e.g., C position, even though no bone perforation has occurred). Bilateral sublingual arteries enter through the lingual foramen within the lingual plate below the genial tubercles in the mandible. As this anastomo-sis transverses within the anterior mandible, the canal is termed the median vascular canal. Bleeding in this area may be signi-cant; however, it is not associated with any type of neurosensory impairment. e presence and size of the sublingual anastomosis and the median vascular canal is most commonly seen on a cross-sectional or axial image of a CBCT scan. If a large anastomosis is present, the position of the planned osteotomy may need to be modied.Management. If signicant bleeding occurs after implant oste-otomy in the midline, a direction indicator or surgical bur can be placed in the osteotomy site to apply pressure. If the osteotomy is completed, an implant may also be introduced into the site, which will compress the walls of bone, thus slowing the bleeding process (Fig. 31.12). In most cases intraosseous bleeding is more easily controlled in comparison with soft tissue hemorrhage. Inferior Alveolar Artery. e inferior alveolar artery is a branch of the maxillary artery, one of the two terminal branches of the external carotid. Before entering the mandibular foramen, it gives o the mylohyoid artery. In approximately the rst molar region, it divides into the mental and incisal branches. e mental branch exits the mental foramen and supplies the chin and lower lip, where it eventually will anastomose with the submental and inferior labial arteries. e exact location of the inferior alveolar artery is easily determined via a CBCT evaluation in the pan-oramic or sagittal views.Management. Normally the inferior alveolar artery is located superiorly to the inferior alveolar nerve within the bony mandib-ular canal. Drilling or placing an implant into the inferior alveo-lar canal may predispose to signicant bleeding. Hemorrhage may be controlled by placement of an implant or direction indicator short of the canal. A 2.0-mm safety zone between the implant and canal should be adhered to. If bleeding does occur, follow-up postoperative care is essential because hematoma for-mation within the canal may lead to a neurosensory impairment. is condition should be monitored because it may progress to respiratory depression via a dissecting hematoma in the oor of the mouth (Fig. 31.13). Incisive Artery. e incisive artery is the second terminal branch of the inferior alveolar artery, which is a branch of the maxillary artery. e incisal branch continues anteriorly after sup-plying the mandibular rst molar area, where it innervates the incisor teeth and anastomoses with the contralateral incisal artery. In rare cases the incisive canal is large, lending to greater bleed-ing during osteotomy preparation or bone-grafting procedures.11 e exact location of the incisive canal is easily determined via a CBCT evaluation in the panoramic or sagittal views.AB• Fig. . (A) Ideal incision location and full-thickness reflection will reduce bleeding with atraumatic reflection of the tissue. (B) Split-thickness flap, which results in increased bleeding and tissue trauma.• Fig. . Median Vascular Canal. In the mandibular midline, the radio-lucent canal that houses the right and left sublingual anastomosis. 780PART VI Implant SurgeryManagement. Bleeding complications can occur when implants are placed into the mandibular incisive canal, which contains the incisive artery. If bleeding does occur during placement of the implant, a direction indicator, surgical bur, or implant can be placed into the osteotomy to apply pressure (Fig. 31.14). Mandibular Anterior: Extraosseous Vesselse anterior mandible is usually known as a safe area for implant placement, but in certain situations it may present with a signicant undercut on the lingual aspect between the foramina. Life-threaten-ing hemorrhage has been reported when a drill perforates the lin-gual plate of the sublingual region of the mandible and traumatizes a sublingual or submental artery, especially in the canine region.12,13If perforation of the lingual cortical plate is associated with arterial bleeding, it is critical to identify its origin and treat aggres-sively. e origin of bleeding in the oor of the anterior region of the mouth may be from the lingual artery, facial artery, or one of its branches. e submental artery originates from the facial artery and courses along the inferior border of the mandible. e sublin-gual artery, a branch of the lingual artery, runs along the inferior border of the mandible and terminates in the midline. Perforation in this area may lead to bleeding, causing an expanding ecchymo-sis (sublingual hematoma) and compromising the airway.Sublingual Artery (Lingual Artery). e lingual artery is a branch of the external carotid artery between the superior thyroid and facial arteries. e lingual artery courses medially to the greater horn of the hyoid bone and crosses inferiorly and facially around the hypoglossal nerve. It then transverses deep to the digastric and stylohyoid muscles, and courses between the hyoglossus and genioglossus muscles. ere exist four main branches of the lingual artery: the suprahyoid, dorsal lingual, deep lingual, and sublingual.Of clinical signicance to oral implantology is the sublingual artery, which supplies the sublingual salivary gland, mylohyoid and surrounding muscles, and the mucous membranes and gingiva of the mandible. A distal branch runs medially in the anterior lingual mandibular gingiva and anastomoses with the contralateral artery. An additional branch connects with the submental artery under the mylohyoid muscle.14 e lingual artery will anastomose throughout the tongue area, with more anastomoses occurring anteriorly.15 Submental Artery (Facial Artery). e most important branch of the facial artery associated with oral implantology is the sub-mental branch, which is the largest of the branches of the facial artery. e submental branch exits the submandibular gland and proceeds anteriorly on the surface of the mylohyoid muscle, just inferior to the body of the mandible. e submental branch termi-nates as an anastomosis with the sublingual branch of the lingual artery and the mylohyoid branch of the inferior alveolar artery.14Studies have shown that the oor of the mouth and lingual gingiva are supplied approximately 53% by the submental artery and the remaining by the sublingual artery.16 Perforation of the lingual cortical plate may result in trauma to the submental artery. Treatment should include immediate repositioning of the patient in an upright position followed by the application of bimanual pressure. is should be immediately applied, followed by airway management and emergency protocol.Bleeding from the submental artery may be decreased by applying nger pressure over the lower border of the mandible. Doppler ultrasonography studies have shown this to reduce the arterial blood by 25% to 50% at the oral commissure level and 33% to 50% at the inferior border of the nares.17Prevention. Clinical and radiographic evaluation should be completed to ascertain the amount of available bone and osse-ous angulation in the anterior mandible. e length of implants should be carefully evaluated because bicortical stabilization (which may lead to perforation of the lingual plate) is no lon-ger advocated for implant success. is is most important in the mandibular canine position as the arteries are close to the lingual cortical plate. In addition, care should be exercised in elevation of the lingual ap and manipulation of the lingual tissue. Clinical Signicance. Bleeding into the sublingual and sub-maxillary spaces will cause elevation of the tongue and oor of the mouth. Bleeding in these spaces will proceed to airway obstruction because the anterior extension of the hematoma is limited by the supercial layers of the cervical fascia.18 e signs and symptoms of sublingual swelling include immediate or delayed (up to 4–8 hours after surgery) elevation of the oor of the mouth, protrusion of the tongue, profuse intraoral bleeding, diculty in swallow-ing, and respiratory depression. e submandibular swelling may dislocate the trachea to the contralateral side and compromise the airway.19 In addition, pulsatile hematomas (pseudoaneurysms) of the lingual artery may result from the injury (Fig. 31.15).20 • Fig. . Incisive Canal Vessels. The incisive canal is the radiolucent canal extending anterior from the mental foramen and mandibular canal. Implants placed into this area may cause increased bleeding.• Fig. . Implant placement into the mandibular canal, which may result in excessive bleeding from the inferior alveolar artery. 781CHAPTER 31 Dental Implant ComplicationsManagement. Immediate bimanual pressure should be applied tothebleedingareaifthelocationcanbedetermined.A4×4gauze may be used to apply the bimanual compression downward from the oor of the mouth (lingual surface of the mandible) and in an upward direction from the submental skin area. e patient should be repositioned from a supine to an upright position. Young forceps may be used to pull the tongue outward, which will slow the bleeding. Airway obstruction should be of vital con-cern because this may lead to a life-threatening situation. If any clinical signs of airway obstruction exist (e.g., dyspnea, dyspha-gia, wheezing, stridor, cyanosis), emergency intervention should be summoned immediately. Ligation of the bleeding vessel is the ideal treatment to control the hemorrhage. is may be dicult in an oce setting because of the location and surgical access of the bleeding vessel. To obtain denitive control of sublingual artery bleeding, surgical intervention with selective ligation of the branches, along with arterial embolization via interventional angi-ography, is indicated (Fig. 31.16).21 PerforatingAnastomosing Branchesof Right Sublingual andLeft Submental ArteriesMucosal andCortical Branches ofLeft SublingualArterySubmentalArteryCortical Branch ofRight SubmentalArteryAB C• Fig. . (A) Sublingual and submental artery anatomy in the floor of the mouth. (B) Perforating lingual plate, which may cause sublingual bleeding. (C) To slow the bleeding, bimanual pressure with a 4 × 4 gauze on the lingual surface of the mandible and extraoral pressure on the inferior mandible. (From Loukas M, Kinsella CR Jr, Kapos T, et al: Anatomical variation in arterial supply of the mandible with special regard to implant placement. Int J Oral Maxillofac Surg 37(4):367–371, 2008.) 782PART VI Implant SurgeryMandibular Posterior: Extraosseous VesselsPosterior Lingual Undercut. In the mandibular posterior area a lingual undercut may be problematic and dicult to manage. In this area, perforation of the lingual plate can occur easily, thereby causing bleeding episodes, with an origin that may be dicult to locate. Life-threatening situations may result from sublingual bleeding. Violation of this area may cause infection or constant irritation from the extruded implant in the soft tissue. If the perfo-ration were to occur above the mylohyoid muscle, damage to the lingual nerve could result in a neurosensory impairment.Prevention. A clinical examination should always be carried out to determine whether an osseous undercut exists. is may be conrmed with a CBCT examination because cross-sectional images are an eective way of observing lingual undercuts. In addition, angulation and positioning must be continuously veri-ed to prevent inadvertent perforation. Studies have shown that lingual undercuts occur in approximately 66% of the population, with a mean undercut of 2.4 mm.22 Accurate measurements must be made to prevent overpreparation of the osteotomy site in the posterior mandible.ABCD• Fig. . Sublingual Hematoma. (A) Four implants placed flapless in the anterior mandible. (B) Resul-tant sublingual hematoma with airway compromise. (C) Axial computed tomography images showing extent of hematoma (blue arrows) with airway compromise. Note perforation of lingual cortical plate (red arrow). (D) Young forceps may be used to pull tongue out to decrease the bleeding and helps maintain airway until medical assistance arrives. (From Limongelli L, Tempesta A, Crincoli V, etal: Massive lingual and sublingual haematoma following postextractive flapless implant placement in the anterior mandible. Case Rep Dent. 2015;2015:839098.) 783CHAPTER 31 Dental Implant ComplicationsAccurate visualization of this area is most easily completed with a CBCT examination. Osteotomy angulation should always be carefully evaluated because improper drilling angu-lation may lead to perforations. In addition, hourglass man-dibles, which have been shown to have an incidence rate of approximately 4%, should always be concerning because per-foration will occur.23In addition, clinical palpation of the ridge during osteotomy preparation will minimize perforations and decrease complica-tions. During osteotomy preparation, handpiece control must be maintained to minimize inadvertent lingual plate perforation. Management. If sublingual posterior bleeding (submental or sublingual arteries) occurs, the patient should be repositioned in an upright position and bimanual pressure should be applied to the area of bleeding. If the airway is compromised, immediate emergency assistance should be summoned (Fig. 31.17). Buccal Artery. A popular donor site for autogenous grafting is the lateral ramus area in the posterior mandible. When making the incision lateral to the retromolar pad, a common blood vessel to damage is the buccal artery. e buccal artery is a branch of the maxillary artery and will most likely cause a signicant bleeding episode. is artery runs obliquely between the internal pterygoid and the insertion of the temporalis on the outer surface of the buccinator.Prevention. In most cases damage to the buccal artery is impos-sible to avoid. Incision and reection will usually encompass the area of buccal artery location. When performing surgery in this area, a curved hemostat should always be available for immediate access to clamp the vessel. Management. A curved Kelly hemostat should be used to con-trol the bleeding. It should be left in place for 3 to 5 minutes until clotting is complete. If bleeding persists, a ligature may be placed with Vicryl suture material (Fig. 31.18). Maxilla: Lateral Wall/Nasal BleedingSignicant bleeding from the lateral approach sinus elevation surgery is rare; however, when it occurs, it has the potential to be troublesome. ree main arterial vessels should be of concern with the lateral approach sinus augmentation. Because of the intraosseous and extraosseous anastomoses that are formed by the infraorbital and posterior superior alveolar arteries, intraoperative bleeding complications of the lateral wall may occur. In some cases this bleeding may be signicant.Extraosseous Anastomosis. e soft tissue vertical release inci-sions of the facial ap in a resorbed maxilla may sever the extraos-seous anastomoses during lateral wall osteotomy preparation for sinus graft surgery. e extraosseous anastomosis on average is located 23 mm from the crest of the dentate ridge; however, in the resorbed maxilla, it may be within 10 mm of the crest. When this artery is severed, signicant bleeding has been observed. ese vessels originate from the maxillary artery and have no bony land-mark to compress the vessel. Vertical release incisions in the soft tissue should be kept to a minimum height, with delicate reec-tion of the periosteum. Hemostats are usually dicult to place on the facial ap to arrest the bleeding. Signicant pressure at the AB• Fig. . Mandibular Posterior Undercut. (A) Three-dimensional image depicting the posterior under-cut. (B) When an undercut is present, limited available height is present for implant placement. This will often lead to a crown/implant ratio issue.• Fig. . Buccal Artery. The buccal artery is often traumatized when making incisions in the retromolar area. 784PART VI Implant Surgeryposterior border of the maxilla and elevation of the head to reduce the blood pressure to the vessels usually slows the bleeding. e elevation of the head may reduce nasal mucosal blood ow by 38%.24 Intraosseous Anastomosis. e vertical component of the lateral access wall for the sinus graft often severs the intraosse-ous anastomoses of the posterior alveolar artery and infraorbital artery, which is on average approximately 15 to 20 mm from the crest of a dentate ridge. Methods to limit this bleeding, which is far less of a risk, include cauterization with the use of a handpiece and diamond bur without water, electrocautery, or pressure on a surgical sponge while the head is elevated. In some cases a second window is made distal to the bleeding area source for access to ligate (Fig. 31.19). Posterior Lateral Nasal Artery. e third artery that implant surgeons should be cautious of is the posterior lat-eral nasal artery (Fig. 31.20). is artery is a branch of the sphenopalatine artery, which is located within the medial wall of the antrum. As it courses anteriorly, it anastomoses with terminal branches of the facial artery and ethmoidal arteries. A signicant bleeding complication may arise if this vessel is severed during elevation of the membrane o the thin medial wall.If the excessive bleeding occurs while the medial wall is ele-vated, the sinus may be packed with hemostatic agents, followed bypackingwithlarge4×4-inchsurgicalspongesandelevationofthe head. Once the bleeding is arrested, the sponges are removed, the layered graft materials may be inserted, and the procedure completed.Epistaxis(activebleedingfromthenose)aftersinusgraftsur-gery is rather common. is may occur with or without a known membraneperforation.Usuallyepistaxisislimitedtotherst24hours after surgery, and the patient should always be warned of this potential complication.A CB• Fig. . Intraosseous Anastomosis. (A) Cross-sectional image showing radiolucent notch on the lateral wall of the sinus. (B) Intraosseous notch (red arrow). (C) Intraosseous anastomosis pulsating bleed (white arrows).AB• Fig. . (A) Posterior lateral nasal artery (red line) in close approximation to the lateral wall of the nasal cavity (medial wall of maxillary sinus). (B) Nasal bleed during sinus augmentation procedure. 785CHAPTER 31 Dental Implant ComplicationsIf bleeding should occur through the nose, there exist numer-ous techniques to obtain hemostasis. Placing a cotton roll, coated with petroleum jelly with dental oss tied to one end, within the nares may obtund nose bleeding after the surgery. After 5 minutes the dental oss is gently pulled and the cotton roll removed. e head is also elevated, and ice is applied to the bridge of the nose. If bleeding cannot be controlled, reentry into the graft site and endoscopicligationby an ENT (ear,nose, and throat)surgeonmay be required.If the orbital wall of the sinus is perforated or if an opening into the nares is already present from a previous event (i.e., pre-vious sinus surgery), the sinus curette may enter the nares and initiate bleeding. e arteries involved in this site are composed of branches of the sphenopalatine and descending palliative arteries, which are branches of the internal maxillary artery. e posterior half of the inferior turbinate has a venous network, the Woodru plexus, which is highly vascular. A cotton roll with silver nitrate or lidocaine with 1:50,000 epinephrine is also eective in obtaining hemostasis. Postoperative Bleeding ControlPatient EducationIt is imperative that patients understand that minor oozing may persist for up to 24 hours after dental implant surgery. If the patient is taking anticoagulants, this may persist for up to 48 hours. e patient should be instructed on the use of pres-sure dressings, and special care should be taken to minimize any trauma to the surgical site (e.g., eating, pulling on lip to see surgi-cal site). e patient should avoid rinsing the mouth vigorously. All postoperative instructions should be reviewed with the patient and given in writing before surgery.Patients should be instructed to limit their activities for a mini-mum of 24 hours, depending on the extent of the surgery. e head should be elevated as much as possible during the daytime hours, and the use of two pillows (i.e., elevate head) during sleep-ing will reduce secondary bleeding episodes.Postoperative hemorrhage in anticoagulated patients may lead to signicant issues. Studies have shown bleeding episodes in anti-coagulant patients will most likely occur within 6 days of the sur-gery.25 In patients who have exhibited signicant bleeding during surgery, hemorrhagic shock, although rare, should be evaluated. If the patient displays any signs or symptoms of shock (e.g., tachy-cardia, hypotension, lethargy, disorientation, cold/clammy skin), immediate medical assistance should be summoned. Treatment would include intravenous uid replacement to replenish the intravascular volume and restore tissue perfusion. Finally, caution should be exercised on the postoperative use of medications that may increase bleeding. A comprehensive review of the patient’s medications should be completed to determine whether any drug interactions may exist that would increase bleeding. Agents that interfere with platelet function should be avoided for routine analgesia (e.g., nonsteroidal antiinammatory drugs [NSAIDs], aspirin) unless the benet outweighs the increased risk for bleed-ing. e routine perioperative use of aspirin should usually be avoided because of an increased risk for bleeding and lack of ben-et. However, if these medications are administered for a separate indication under the recommendation of a physician (e.g., recent stroke, acute coronary syndromes, implanted coronary stent), they should be continued. Techniques to Decrease and Control Bleedinge need to control gross bleeding is paramount for successful surgery because insidious and continuous loss of blood from arteries, veins, or capillaries can become signicant if bleeding is not controlled. Dental implant clinicians have numerous options for maintaining hemostasis, which include mechanical, thermal, pharmacologic, and topical agents.Mechanical Methodse most common primary mechanical method to control bleed-ing is to apply direct pressure or compression on the bleeding site, along with repositioning the patient. Secondary mechanical meth-ods include suturing, clamping the blood vessel with hemostats, and ligating the bleeding vessel with suture material.Positional Changes. When signicant bleeding occurs, main-taining the patient in a supine position is not recommended because of increased bleeding (head below the heart). Hydrostatic pressure occurs within the vascular system because of the weight of the blood vessels and is dependent on gravity. e pressure is decreased in any vessel above the heart and increased in blood vessels below the heart. Studies have shown that in an upright position, the average pressure at the level of the heart is 100 mm Hg. Vessels in the head and neck averaged 49 and 186 mm Hg, respectively, at the foot level.26 Repositioning the patient to an upright position (head above the heart) will not stop the bleed-ing; however, it will signicantly decrease the hemorrhage (studies have shown a decrease up to 38%).27 Direct Pressure. If signicant intraoperative bleeding occurs, the ideal treatment should involve immediate application of pres-sure to the surgical site. Pressure or compression directly on the blood vessel will allow for platelet aggregation and initiation of the coagulation cascade. Pressure may be applied manually or by the patient biting forcefully on a gauze dressing. Pressure should be maintained for at least 3 to 5 minutes to allow the formation of a blood clot. Caution should be exercised not to remove the gauze too early because this may dislodge the clot.Ideally3×3or4×4gauzeshouldbeusedbecause2×2gauzemay be accidentally aspirated. In primary bleeding, pressure is the simplest and fastest method to control bleeding before the use of hemostatic measures. Suturing. Suturing plays a signicant role not only in obtain-ing primary closure for ideal healing but also for maintaining hemostasis (direct versus indirect). Direct placement of a suture (ligation) is used when there is access to a deep bleeding ves-sel. e suture is placed by entering the tissue at least 4 mm from the bleeding vessel, 3 mm below the vessel, and 4 mm exiting the tissue. is will ligate or occlude the vessel as long as it is placed proximal to the bleeding area. A gure-eight suture technique is ideally used. Indirect suture placement is used to retract the tissue and minimize bleeding via pressure from the accumulated tissue. is is most often used as tie-backs when reecting an edentulous mandible (cuspid to molar bilaterally). And lastly, good suturing technique is paramount for prevent-ing reactionary bleeding after surgery. Ideally interrupted or mattress sutures should be placed in conjunction with continu-ous sutures to maintain closure. A suture material that exhibits high tensile strength is recommended, such as polyglycolic acid (e.g., Vicryl). e interim prosthesis should be modied to have no direct pressure on the wound site, as this may dislodge the sutures (Fig. 31.21).  786PART VI Implant SurgeryClamped Vessel With Hemostat Forceps. When local mea-sures are not successful in controlling bleeding, a hemostat may be usedtoclampthebloodvessel.UsuallyacurvedKellyhemostatmay be used to clamp the vessel to control the bleeding via two mechanisms: 1. e rst mechanism is occluding the vessel and damaging the blood vessels wall to stimulate clotting. is clamping pressure should be maintained for approximately 2 to 3 minutes, which will usually allow for hemostasis. However, this method may be unreliable because the clot may become dislodged and post-operative bleeding may occur after removal of the hemostat.2. A more successful technique in controlling bleeding is to use ne-pointed hemostats (Kelly hemostats) and ligate the bleed-ing vessel with suture material. e vessel should be clamped to obtain immediate hemostasis, with the tip of the hemostat extending beyond the vessel. A clamped vessel may be ligated with suture material such as an absorbable suture with high tensile strength (e.g., Vicryl). A tie should be placed around the hemostat, extending to the vessel. e hemostats are then removed, and two additional throws are made with the suture. Usually bleeding from vessels of 2 mm or greater diametershould be ligated. Direct ligation of the bleeding blood ves-sel is usually the most eective technique in stopping arterial blood ow. However, exposure and identication of the bleed-ing vessel may sometimes be extremely dicult. In addition, the bleeding may occur from multiple capillaries, which may result in dicult hemostasis. Electrocautery. Electrocauterization,developedinthe1930s,has been one of the most common hemostatic techniques because ofitslowcost,accessibility,easeofuse,andeectiveness.Electro-cautery is the process of destroying tissue using heat conduction, with a probe that is heated by an electric current. Dierent proce-dures may be completed with the use of high radiofrequency alter-nating current for cutting, coagulating, and vaporizing tissues. Electrocauteryismosteectiveonsmallvesselsandmaybeusedin two modes: monopolar and bipolar (Fig. 31.22).Monopolar electrosurgery delivers current using dierent types of waveforms (i.e., modes). e coagulation mode uses an inter-rupted waveform, which generates heat, thereby coagulating a cell, a phenomenon also termed fulguration. e cutting mode is low energy, which produces a cutting eect to vaporize tissue with minimal hemostasis. e blend mode simultaneously cuts tissue and coagulates bleeding. is technique is often dicult to use in implant surgery because access and a relatively dry eld is needed to cauterize the vessel. A dry eld is needed for the eective electri-cal current to pass through the tissues. A high-speed plastic, not metal, suction tip should be used to maintain a dry eld. Buzzing the Hemostat (Electrocautery + Hemostat Ligation). Usually on larger vessels the combination of a clamped vessel(with curved hemostat) and electrocautery will allow for the cau-terizing of the blood vessel, thus stopping blood ow in the vessel. e protocol is as follows: 1. Usethelowestpossiblesettingtoachievethedesiredeect.2. Use the CUT mode, not the COAG mode. COAG has ahigher peak-to-peak voltage and is more prone to alternate (small) current pathways.AB• Fig. . Electrocautery. (A) Monopolar electrocautery, which uses current to establish hemostasis. A ball electrode is the most common to be used; however, access is sometimes difficult. (B) A battery-operated disposable cautery unit that does not use current, however generates heat to ligate the blood vessel.AB• Fig. . Suturing. (A) Direct ligation with figure-eight suturing tech-nique. (B) Indirect tie-back of the mandibular lingual tissue from cus-pid-molar contralaterally, which decreases bleeding, allows for ease of retraction, and prevents tissue trauma. 787CHAPTER 31 Dental Implant Complications 3. After clamping the vessel, touch the active electrode to the hemostat closer to the patient (below the hand holding the hemostat) and then activate the electrode. is minimizes sparking and the subsequent demodulation of current, while encouraging a path of least resistance. NOTE: Care should be exercised because the implant clini-cian may receive burns or be shocked even when wearing pro-tective gloves. When the surgeon clamps a bleeding vessel and the electrode is touched to the hemostat, the tissue between the clamped hemostat is coagulated. e “buzzing” may cause high-voltage breakdown of the surgeon’s glove, leading to a burn. To minimize this possibility, the surgeon’s glove should be changed, if wet, because hydrated gloves show a lower resistance. In addition, the electrode should be placed in contact with the hemostat before activation of the electrosurgical current, to minimize the produc-tion of a spark (Fig. 31.23). Lasers. Lasers, which are gaining popularity as a tool in den-tal surgery, may also be used to achieve hemostasis. Laser is an acronym for “light amplication by stimulated emission of radia-tion,” which produces laser light energy. Laser energy delivered to an area of bleeding may be reected, scattered, transmitted, or absorbed. e extent of the tissue reaction depends on the laser wavelength, power settings, spot size, and length of contact time with the bleeding area. Lasers have been shown to be a safe or useful modality in treating dental surgery patients with bleeding disorders.28 Pharmacologic TechniquesAlthough pharmacologic techniques may be used in implant den-tistry to control bleeding, the success of maintaining hemostasis is questionable, with varying results.Epinephrine. Epinephrinemaybeusedtoenhancehemostasisin combination with local anesthesia (e.g., 2% Lidocaine 100,000, 1/50,000 epinephrine). When locally placed, epinephrine will reduce bleeding, slow the absorption of the local anesthetic, and prolong the anesthetic and analgesic eect. e hemostatic prop-erties are related to platelet aggregation, which leads to a decrease in the adrenoreceptors within the vessel walls, thus producing vasoconstriction. However, rebound hyperemia may result post-operatively, which will increase bleeding. Various studies have shown that topical application of a 1/100,000 concentration of epinephrine creates vasoconstriction and controls hemostasis with sinus graft procedures, with no appreciable changes in systemic hemodynamics.29 Tranexamic Acid Solution. Tranexamic acid 4.8% is an anti-brinolytic oral rinse that facilitates clot formation by inhibiting the activation of plasminogen to plasmin. Plasmin prevents the clotting process from initiating brinolysis. Tranexamic acid solu-tion may be used as a mouthwash postoperatively and has been shown to enhance clotting in patients with coagulopathies or anti-coagulant therapy. Sindet-Pedersen and Ramstrom30 showed a sig-nicant reduction in postoperative bleeding with a 10-mL rinse, four times a day for 7 days postoperatively. Choi etal.31 reported a signicant decrease in bleeding during maxillary surgery after a bolus of tranexamic acid was given preoperatively (Fig. 31.24). Topical Hemostatic Agents. Absorbable topical hemostatic agents are used when conventional methods of hemostasis are ineective. ese agents may be placed directly into the bleed-ing site to decrease bleeding during the procedure or during the postoperative interval. ey work either mechanically or by aug-menting the coagulation cascade. e topical hemostatic agents have the added benet of minimizing the possibility of systemic blood clots, which are drawbacks of systemic hemostatic agents. ere are two types: active and passive (Table31.1). Active Hemostatic AgentsThrombin. Active topical hemostatic agents have biologic activity that induces clotting at the end of the coagulation cas-cade. Most active agents used in dental implant surgery con-tain the coagulant thrombin. rombin is a naturally derived AHemostatBlood vesselBC• Fig. . (A–C) “Buzzing the hemostat” usually used for larger-vessel ligation (arterial). The vessel is clamped with the hemostat, and the electrocautery unit is placed on CUT mode and lightly touches the hemostat. A spark will usually result (arrow). Before its use, supplemental oxygen (nasal cannula) should be discontinued to prevent a patient airway fire. 788PART VI Implant Surgery Active and Passive Hemostatic AgentsCOMMON HEMOSTATIC AGENTSType Product Advantages DisadvantagesCollagen OraTape, OraPlug (Salvin), CollaTape, CollaPlug (Zimmer)Inexpensive; resorbs in 10–14 days; highly absorbent to many times its own weightNoneMicrocellular collagen Avitene (Davol), Helitene (Integra), Instat (Ethicon)Good application for large surfaces; supe-rior hemostasis to gelatin and celluloseDifficult to handle; expensiveGelatin GelFoam (Baxter), Surgiform (Ethicon) Swelling after application results in tam-ponade effect; neutral pHMay cause tissue/neural damage due to compression from swelling; possible dislodgement from bleeding siteCellulose Surgicel (Ethicon), Blood Stop (Salvin), Oxycel (Becton Dickinson), ActCel (Coreva Health Sciences)Easy to handle; low pH provides antimi-crobial coverage; expands three to four times its original size and converts to a gelPossible foreign body reaction; low pH may lead to possible postoperative irritation; needs to be removedThrombin Thrombin-JMI Bovine (Pfizer), Evithrom-human (Ethicon), Reco-throm-recombinant (ZymoGenetics)Can be added to collagen products, good for small-vessel bleedingBovine has been shown to be immuno-genic; leads to severe coagulopathyThrombin + gelatin FloSeal (Baxter) Very good for arterial bleeding areas because it acts as an adhesiveCan result in significant swelling from the compression; can cause neural disturbanceFibrin sealant Tisseel (Baxter)Evicel (Ethicon)Good for larger bleeding areas because it acts as an adhesiveExpensive; preparation timeKaolinite QuikClot (Z-Medica) Kaolin is a natural occurring mineral Limited use in dental surgery; needs to be poured into wound; exothermic reaction causes heatSynthetic bone hemo-static agentsBone waxOstene (Ceremed)Ostene is soluble; it dissolves in 48 hours and is not metabolized, with a low bac-terial adhesion and infection rateBone wax is insoluble; must be removed or will cause inflammation and a foreign body giant cell reaction; should not be used in implant dentistry TABLE 31.1AB• Fig. . Tranexamic Acid Injection. (A) Injection solution (Auromedics, East Windsor, N.J.). (B) Inject-able tranexamic acid placed under bleeding flap. 789CHAPTER 31 Dental Implant Complicationsenzyme that is formed from prothrombin and acts as the basis for a brin clot by converting brinogen to brin. It is mainly used as a topical hemostatic agent in 5000- to 10,000-unit solutions, which accelerates capillary bleeding. It may be used as a powder or combined with a gelatin sponge during surgical procedures.rombin bypasses the initial enzymatic process, thereby exert-ing its eect by impairing aspects of the coagulation cascade. For thrombin to maintain hemostasis, circulating brinogen is needed because it is necessary for the formulation of a clot. erefore when a patient exhibits the absence of brinogen, thrombin will not be eective. Fibrinogen is less susceptible to coagulopathies caused by clotting factor deciencies and platelet dysfunction.32 However, thrombin does work in the presence of antiplatelet and anticoagulation medications, which are quite prevalent in the population (Fig. 31.25).Types of rombin. rombin is available in many forms as a hemostatic agent and has been puried from numerous sources and classied according to the plasma used to create it. Bovine thrombin (e.g., rombin-JMI) is available as a powder that may be used dry, reconstituted with sterile saline, or added to gelatin sponges or collagen. Antibody formation has been associated with bovine thrombin, and this may lead to coagulopathies.33Human plasma thrombin (e.g., Evithrom) is available as afrozen liquid that can be reconstituted via an absorbable gelatin sponge. Human plasma thrombin has been associated with the potential risk for viral or disease transmission.34Recombinant thrombin (e.g., Recothrom) is a genetically engi-neered thrombin available in a powder form. It may be applied via a spray kit or with an absorbable gelatin sponge. e use of recombinant thrombin eliminates the risk for antibody formation and disease and virus transmission.35 Advantages. rombin use is advantageous in patients receiv-ing antiplatelet or anticoagulation medications. rombin does not need to be removed from the bleeding site because degenera-tion and reabsorption of the brin clot is achieved during the nor-mal healing process. Usually thrombin-containing active agentshave a rapid onset of action, providing hemostasis within 10 min-utes in most patients.36 Disadvantages. rombin is ineective in patients who suer from abrinogenemia because brinogen will not be present in the patient’s blood. Care should be exercised not to use thrombin directly on larger vessels because systemic absorption may lead to intravascular thrombosis. Passive Hemostatic Agents. Passive hemostatic agents provide hemostasis by accelerating the coagulation process. ese agents form a physical, lattice-like matrix, which activates the extrinsic clotting pathway and provides a platform for platelets to aggregate and form a clot. Passive hemostatic agents are eective only on patients who have an ideal coagulation process. If the patient suf-fers from any type of coagulopathy, other hemostatic techniques should be used. Passive hemostatic agents are available in many dierent forms (e.g., bovine collagen, cellulose, gelatins) and application meth-ods (e.g., absorbable sponge, foam, pads that may absorb several timestheirownweight).Expansionmayleadtocomplications,specically pressing on neural tissue (e.g., inferior alveolar nerve). erefore after hemostasis is obtained, passive hemostats should be removed to minimize postoperative complications. Passive hemostatic agents are readily available and inexpensive.Collagen. Collagen-based hemostatic agents work by contact activation and promotion of platelet aggregation, which occurs as a result of contact between blood and collagen. Collagen is avail-able in many carrier forms such as a powder, paste, or sponge. Studies have shown that between 2% and 4% of the total popula-tion is allergic to bovine collagen.37 Bovine Collagen (OraPlug, OraTape; Salvin Dental Specialties, Inc.). Products such as OraPlug and OraTape are soft, white, pli-able, nonfriable, coherent, spongelike structures that are fabricated from bovine collagen (usually from deep exor tendons). ey are nontoxic, nonpyrogenic, and highly absorbent. Indications include the control of oozing or bleeding from clean oral wounds. ey help control bleeding, by stabilizing blood clots, and protect the wound bed to facilitate the healing process. When applied, the products should be held in place for approximately 2 to 5 minutes to achieve ideal hemostasis and then may be removed, replaced, or left in place. Most collagen materials are completely resorbed within 14 to 56 days (Fig. 31.26).38 Cellulose. e most common cellulose-based hemostatic agent is regenerated oxidized cellulose that initiates clotting via con-tact activation. Oxidized cellulose has been shown to be poorly absorbed and may cause healing complications postoperatively. Regenerated Cotton Cellulose (BloodSTOP; LifeScience PLUS, Inc.). BloodSTOP is a biocompatible, nonirritating, water-solu-ble, regenerated cotton cellulose hemostatic agent that resembles traditional gauze. When applied to a bleeding surgical site, Blood-STOP quickly absorbs blood and transforms into a gel to seal the AB• Fig. . (A) Topical thrombin (King Pharmaceuticals, Bristol, Tenn.). (B) Injected under a flap. 790PART VI Implant Surgerywound with a protective transparent layer, actively aids in blood coagulation, and creates a positive environment for wound heal-ing. Because BloodSTOP is 100% natural cellulose and is water soluble, it is easily removed without disruption of the wound sur-faces after hemostasis. It is manufactured in a single-use, sterile packagewitha0.5×∼2-inch size (Fig. 31.27). MechanicalBeeswax. Bone wax, a soft, malleable, nonbrittle wax, was invented in 1886 by Sir Victor Horsley. e material is a com-bination of beeswax, salicylic acid, and almond oil.39 It is most commonly used when the bleeding is visualized as having an ori-gin from within the bone. is type of bleeding most commonly occurs during osteotomy preparation and extractions. Bone wax exhibits no hemostatic quality; it obliterates the vascular spaces in cancellous bone. However, caution should be exercised with the use of bone wax because it is water insoluble and will not be absorbed. It may predispose the area to infection or inhibit bone healing. Studies have shown that bone wax, when removed from an osseous defect after 10 minutes, completely inhibited fur-ther bone regeneration.40 Bone wax also increases inammation, which may cause a foreign body giant cell reaction and infection at the site (Fig. 31.28).41 Synthetic Bone Hemostat Material (Ostene; Ceremed Inc.). Ostene is a synthetic bone hemostat material approved in 2004 by the FDA for use in cranial and spinal procedures. is material is a mixture of water-soluble alkylene oxide copolymers that elicits minimal postoperative inammation. It has many advantages over ABC• Fig. . (A and B) BloodSTOP hemostatic agent (LifeScience PLUS, Inc., Mountain View, Calif.). (C) BloodSTOP placed in extraction site.AB• Fig. . (A and B) Bone wax. (B: Courtesy Surgical Specialties, Wyo-missing, Pa.)ABC• Fig. . Collagen Hemostatic Agents. (A) OraTape. (B) OraPlug. (C) Collagen hemostatic agent placed to control bleeding. (A and B: Courtesy Salvin Dental Specialties, Charlotte, N.C.) 791CHAPTER 31 Dental Implant Complicationsbone wax because it is water soluble and dissolves in 48 hours. It has been associated with a decreased infection rate and positive bone cultures.42 Ostene is supplied in sterile peel pouches and is applied in a manner similar to bone wax, without the associated disadvantages (Fig. 31.29). Postoperative ComplicationsEdema (Postoperative) Surgical SwellingPostoperative edema is a direct result of tissue injury and is dened as an accumulation of uid in the interstitial tissue. Two variables determine the extent of edema: (1) the amount of tissue injury is proportional to the amount of edema; and (2) the looser the con-nective tissue at the surgery site, the more edema is most likely to be present. Because postoperative swelling can adversely aect the incision line (i.e., result in incision line opening [ILO]), measures shouldbetakentominimizethiscondition.Usuallyedemawillpeak at approximately 48 to 72 hours; therefore patients should always be informed. Increased swelling after the fourth day may be an indication of infection, rather than postsurgical edema.Etiologye mediators of the inammatory process include cyclooxygen-ase and prostaglandins, which play a signicant role in the devel-opment of postoperative inammation and pain. When tissue manipulation or damage occurs, phospholipids are converted into arachidonic acid by way of phospholipase A2 (PLA2). Arachidonic acid, which is an amino acid, is released into the tissue, which pro-duces prostaglandins via enzymatic breakdown via cyclooxygen-ases. e end result is the formation of leukotrienes, prostacyclins, prostaglandins, and thromboxane A2, which are the mediators for inammation and pain. PreventionGoodsurgicaltechniquemustbeusedwithminimaltissuetraumato decrease postoperative swelling. Additional factors include patient systemic disorders, excessive retraction, and long surgical duration, which will all contribute to increased inammation after surgery. Postoperative prophylactic medications such as ibuprofen (NSAIDs) and glucocorticosteroids (steroids) are used as prophy-lactic medications, which counteract the negative eects of the edema cascade.Nonsteroidal Anti-inammatory Drugs. NSAIDs have an anal-gesic eect, as well as an anti-inammatory eect. is drug class reduces inammation by inhibiting the synthesis of prostaglandins from arachidonic acid. erefore the use of the popular analgesic drug ibuprofen has a secondary benecial anti-inammatory eect. NSAIDs do not have a ceiling eect for inammation (i.e., ceiling eect for analgesia is 400 mg); however, higher doses to achieve anti-inammatory qualities are accompanied by serious side eects.Recommendation: Ibuprofen 400 mg for type 1 to 4 procedures (see Chapter 14). Glucocorticosteroids. e adrenal cortex, which uses choles-terol as a substrate, synthesizes and secretes two types of steroid hormones—the androgens and corticosteroids. e corticoste-roids are classied additionally by their major actions: (1) gluco-corticoids, which have eects on carbohydrate metabolism and have potent anti-inammatory actions; and (2) mineralocorti-coids, which have sodium-retaining qualities. e use of synthetic glucocorticosteroids has become popular in the postoperative management of inammation after oral surgical procedures. ese synthetic glucocorticoids have greater anti-inammatory potency in comparison with natural steroids, with very little sodium and water retention. Most steroids have similar chemical structures; however, they dier in their milligram potency.43 e anti-inammatory eects are achieved by altering the connective tissue response to injury, causing a decrease in hyperemia, which results in less exudation and cellular migration, along with inltration at the site of injury.44Glucocorticoidsbindto glucocorticoidreceptorswithin cellsandformaglucocorticoidreceptor(GR) complex. is complex alters the synthesis of messenger RNA from the DNA molecule, aecting the production of dierent proteins. By suppressing the production of proteins that are involved in inammation, glu-cocorticoids also activate lipocortins, which have been shown to inhibit the action of Phospholipase A2 (PLA2).PLA2 is a key enzyme involved in the release of arachidonic acid from cell membranes.Arachidonic acid is an omega-6 fatty acid that is incorporated into cell membranes. When a cell is damaged, arachidonic acid is released from cell membranes and is converted into inamma-tory and pain prostaglandins by cyclooxygenase-2 enzymes. e release of arachidonic acid requires the activation of enzyme PLA2. However, lipocortins, which cause the inhibition of PLA2, prevent the release of arachidonic acid, thereby reducing the amounts of inammatory prostaglandins.A wide range of glucocorticoid preparations are available for local, oral, and parenteral administration. In relation to the naturally occurring cortisol (hydrocortisone), synthetic gluco-corticoids are longer acting and more potent. e main dier-ences are based on the classication as short acting (<12 hours), intermediate acting (12–36 hours), and long acting (>36 hours). A summary of the most common glucocorticosteroids is shown in Table 31.2.e ideal synthetic glucocorticoid for dental implant surgery should maintain high anti-inammatory potency with minimal mineralocorticoid eects. e glucocorticoid that best suits the requirements is the long-acting glucocorticoid dexamethasone (Decadron). It is imperative this drug be administered before sur-gery so that adequate blood levels are obtained. Also, it should be given in the morning in conjunction with the natural release of cor-tisol (∼8:00 a.m.). is timing will interfere the least with the adre-nocortical system. Because inammation usually peaks between 48 and 72 hours, the postoperative regimen of dexamethasone should • Fig. . Ostene (Bone Hemostasis Material) (Baxter). Ostene material is a sterile water-soluble surgical implant material. It can be used for the control of bleeding from bone surfaces by acting as a mechanical barrier. 792PART VI Implant Surgerynot exceed 3 days after surgery. is high-dose, short-term gluco-corticoid therapy has been shown not to signicantly aect the hypothalamic-pituitary-adrenal axis, which controls many of the body’s processes, including reactions to stress.45A signicant additional benet of the administration of dexa-methasone is the potent antiemetic eects for the prophylactic treatment of postoperative nausea and vomiting. is is now an accepted medication for hospital-based outpatient surgery, usually given in doses of 8 to 10 mg intravenously.46Contraindications to the use of corticosteroids include active infections (viral, bacterial, fungal), tuberculosis, ocular herpes simplex, primary glaucoma, acute psychosis, and diabetes mel-litus. Special attention must be given to patients with diabetes because glucocorticoids have an anti-insulin action that results in increased serum glucose and glycosuria.47Usuallycorticosteroidsare contraindicated with patients with insulin-dependent diabe-tes. For patients with oral and diet-controlled diabetes, a medical consult should be completed before any treatment.Recommendation: Decadron 4 mg for type 1 to 4 procedures (see Chapter 14). Cryotherapy. Cryotherapy (application of ice) is one of the simplest and most economical modalities in the management of postoperative soft tissue inammation. e use of ice to reduce painandswellingdatesbacktotheancientEgyptians,morethan4000 years ago.48e use of cryotherapy is highly advised in any dental implant procedure in which excessive inammation is expected. e mechanism of action involves a reduction in uid accumulation within the body tissues, slowing of metabolism, control of hemor-rhage, and a decrease in the excitability of peripheral nerve bers leading to an increase in pain threshold.49Caution must be taken to limit the application of ice to no lon-ger than 2 days because prolonged use may cause rebound swelling and cell destruction. Improper and prolonged use of ice may result in cell death caused by prolonged vasoconstriction, ischemia, and capillary thrombosis.50After 2 to 3 days, moist heat may be applied to the region to increase blood and lymph ow to help clear the area of the inammatory consequences. is also helps reduce any ecchymo-sis that may have occurred from the tissue reection. Although usually safe, the application of ice is cautioned in patients suer-ing from cold hypersensitivities and intolerances and peripheral vascular diseases. In addition, ice application may be problematic in patients who are elderly or very young because they may have impaired thermal regulation and limited ability to communicate.Care should be exercised in using facial bandages because pro-longed ice administration may result in soft tissue injury.Recommendation: Cold dressings (ice packs) should be applied extraorally (not directly on skin: place a layer of dry cloth between ice and skin) over the surgical site for 20 minutes on/20 minutes o for the rst 24 to 36 hours (Fig. 31.30). Decrease Activities. Patients should be instructed to decrease activities after surgery because this will minimize swelling post-operatively. e more active the patient and the more strenuous activity the patient engages in, the greater the extraoral swelling.AB• Fig. . (A and B) Common postoperative complications of (A) edema and (B) ecchymosis. Synthetic GlucocorticoidsGlucocorticoidsAnti-inflammatory PotencyEquivalent Dose (mg)Duration (hr)Short actingHydrocortisone 1.0 20 <12Cortisone 0.8 25 <12Intermediate actingPrednisone 4.0 5 24–36Prednisolone 4.0 5 24–36Long actingDexamethasone 25 0.75 48 TABLE 31.2 793CHAPTER 31 Dental Implant ComplicationsRecommendation: Activities should be limited for the rst 3 days.Elevationofthehead(sittingupright)andsleepingonmul-tiple pillows will minimize the postoperative swelling. TreatmentSwelling is self-limiting and once it occurs, it is usually dicult to treat (time dependent). e earlier mentioned medications/therapy (Decadron, NSAIDs, cryotherapy) will help to reduce postoperative inammation, especially after longer, more invasive surgeries. Ecchymosis (Bruising)Ecchymosisissubcutaneousextravasationofbloodwithinthetis-sues, which results in discoloration of the skin from the seepage of blood in the tissues. e location of the ecchymosis may be distant to the surgical site because of gravity (i.e., always inform patientspreoperatively).Ecchymosisthatpresentsintheinferiormandibular area or neck may be from bleeding under the ap and traveling via fascial spaces because of gravity.Etiologye cause of ecchymosis (bruising) is not conned to an existing hematologic disease or to medication-induced bleeding. Moderate bruising should be expected after dental implant surgery, espe-cially after longer, more invasive surgeries. Female and elderly patients are more susceptible to bruising.e ecchymosis cascade includes: 1. Blood vessels rupture. 2. Red blood cells die and release hemoglobin. 3. Macrophages (white blood cells) degrade hemoglobin via phagocytosis. 4. Hemo > bilirubin = bluish-red color. 5. Bilirubin > hemosiderin = golden-brown color.Ecchymosismayappearasbrightred,black,blue,purple,ora combination of the above colors. It usually consists of nonel-evated, rounded, and irregular areas that increase in intensity over 3 to 4 days postsurgery and will diminish and become yellow as they disappear. It may take 2 to 3 weeks for complete resolution. PreventionUnfortunately, even with gentle handling of tissues and goodsurgical technique, ecchymosis may be unavoidable. To mini-mize ecchymosis, avoid postoperative aspirin, herbal remedies, and food supplements that may increase bleeding. Always inform the patient preoperatively (preferably in written postoperative instructions)thatbruisingmayoccur.Elderlypatientsaremoresusceptible to ecchymosis because of decreased tissue tone and weaker intracellular attachment. TreatmentEcchymosis is self-limiting and usually resolves without treat-ment. However, the patient may treat the ecchymosis in the fol-lowing ways: Rest/avoid strenuous activity: promotes tissue healing and decreases inammationElevation: helps decrease inammation, facilitates proper venous return, and improves circulation to the siteAnalgesics: helps reduce pain associated with the onset of ecchymosisSun exposure: inform patient to avoid sun exposure to the area of bruising because excessive sunlight may cause permanent dis-coloration Dental Implant Periapical Lesions (Retrograde Peri-implantitis)After implant placement and recall examinations, case reports have shown the genesis of periapical lesions (radiolucency), which may suggest a possible precursor to failure of the endosseous implant.51 ese periapical lesions have been termed apical peri-implantitis and retrograde peri-implantitis.52 e lesions have been dened as symptomatic or asymptomatic periapical radiolucency developing after implant placement with a normal coronal bone-to-implant interface.EtiologyAsymptomatic. A clinically asymptomatic periapical radio-lucency is considered to be inactive when radiographically there exists evidence of bone destruction with no clinical symptoms.is may result from placing an implant into a site in which the osteotomy was prepared deeper than the implant length, result-ing in an apical space. Also, when implants are placed adjacent to a tooth with an apical scar, this may result in a radiolucency. Inactive lesions may be caused by thermal bone necrosis, which is a direct result of overheating the bone. e thermal injury may result in a brous tissue interface, which may compromise the prognosis of the implant. Symptomatic. A clinically symptomatic lesion is most com-monly caused by bacterial contamination during implant place-ment. is may occur when an implant is placed into a preexisting area with bacteria (existing infection, cyst, granuloma, or abscess). When lesions are initiated at the apex, they may spread coronally or facially. Clinical symptoms with active lesions include intense pain, inammation, percussion, mobility, or possible stulas tract formation (Fig. 31.31).53 PreventionPrevention of periapical lesions includes the following: 1. Clear evaluation of adjacent tooth structure to rule out preex-isting infection or pathology 2. Pulp testing of adjacent teeth 3. Caution when placing immediate implants into sites with pos-sible pathology4. Extensivedebridementofpathologictissueanddecorticationof immediate extraction sites TreatmentBecause of the multifactorial etiology of periapical lesions around dental implants, there is no accepted general consensus on the treatment. Nonsurgical antibiotic treatment of periapical lesions has been shown to be unsuccessful.54 e following have been shown to be eective treatments of periapical lesions: Exposure: Tissue reection is completed to expose the apical im-plant area (buccal or lingual access).Debridement: e granulation tissue is completely removed to ex-pose the bony walls of the apical area.Removal of implant apex (elective): e apical portion of the im-plant may be removed to gain better access to the bony walls. is should be completed only if there is no biomechanical compromise for the implant.Surface decontamination: e implant surface may be detoxi-ed with various chemicals such as tetracycline (250 mg) grafting,55 citric acid (40%),56 chlorhexidine, and hydrogen peroxide.57,58 794PART VI Implant SurgeryAllograft: e defect area is grafted with allograft material, along with a resorbable membrane. A local antibiotic (e.g., Ancef, Cleocin) should be added to the graft for additional antimi-crobial coverage.Systemic antibiotics: Systemic prophylactic antibiotics (e.g., amoxi-cillin) should be used, together with 0.012% chlorhexidine oral rinse. Titanium Allergy/HypersensitivityHypersensitivity to titanium (Ti) is an ever-increasing reportable complication in medicine today that has been associated with a wide range of situations. In orthopedic medicine there are many case reports of titanium alloy hypersensitivity. Witt and Swann59 reported 13 cases of failed total hip prostheses and concluded the tissue reaction in response to metal-wear debris may have been the causative factor of the failed implants. is process has been termed repassivation and may produce an oxide that surrounds and turns the peri-implant tissues black. Yamauchi etal.60 reported a titanium-implanted pacemaker caused an allergic reaction. e patient experienced development of a distinct erythema over the implantation site, which resulted in a generalized eczema. Tita-nium sensitivity was conrmed by intracutaneous and lympho-cyte stimulation testing.In the dental literature, allergic reactions to pure titanium are rare. However, many authors have suggested there is a higher inci-dence of titanium alloy allergy with respect to dental implants; it is most likely underreported because of a poor understanding of failure or allergy.61 Preez etal.62 have reported a case of implant failure caused by a suspected titanium hypersensitivity reaction around a dental implant. Histologic results showed a chronic inammatory reaction with concomitant brosis. Egusa et al.reported a titanium implant overdenture case that resulted in gen-eralized eczema that fully resolved after implant removal.46 Sicilia etal.,63 in a clinical study of 1500 consecutive implant patients, reported approximately nine implants with a positive reaction to titanium allergy.EtiologySensitivity to titanium has been shown to be a result of the pres-ence of macrophages and T lymphocytes with the presence of B lymphocytes, which results in a type IV hypersensitivity reac-tion.64 All metals, when in a biologic environment, undergo corrosion, which may lead to the formation of metallic ions and trigger the immune system complex with endogenous proteins.65 Titanium alloy dental implants have been shown to contain many “impurities” that may trigger type IV hypersensitivity reactions. Harlo etal.66 used spectral analysis to investigate various tita-nium alloy implants. e results showed that all of the titanium alloy samples contained small amounts of other elements such as beryllium (Be), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), and palladium. ese impurity elements have been shown to be the cause of the hypersensitivity reactions. PreventionA thorough medical history involving any history of titanium hypersensitivity is strongly recommended. TreatmentWhen titanium hypersensitivity is suspected the implants should be removed and the patient should be referred to his or her physi-cian for appropriate testing. Case reports have shown that after complete removal of the implants, complete resolution results.67 Metal sensitivity is usually diagnosed using a “patch test,” which involves placement of titanium (allergen) to the skin for approxi-mately 3 to 4 days. A positive test would include the appearance of an erythematous reaction. However, there is a possibility of false-negative results because the sealing qualities of the skin against direct contact may make the test unreliable (Fig. 31.32). Incision Line OpeningILO is one of the most common complications resulting from dental implant and bone graft surgery, occurring when a wound dehisces along a suture line (Fig. 31.33). e prevalence A B• Fig. . Retrograde Periapical Lesion. (A) Radiolucency on mesial of implant of mandibular implant. (B) Radiolucency on mesial of maxillary implant. 795CHAPTER 31 Dental Implant Complicationsrate of ILO has been shown in studies to range from 4.6% to 40% around submerged implants.68,69 Mendoza et al.70 reported 37% of postimplant surgery patients exhibited no ILO, whereas 43% had partial ILO and 20% had complete ILO. However, when evaluating soft tissue dehiscence around membranes (barriers), studies have shown a 30% incidence rate when part of guided bone regeneration procedures.71 erefore ILO is a common postoperative complication after dental implant and bone-grafting surgery. In this chapter the causative factors, prevention, and management of ILO will be discussed, together with a treatment protocol that is procedure and time specic.Classification of Incision Line Opening ComplicationsWhen placing root form implants with a two-stage approach, spontaneous early exposure of submerged implants has the poten-tial for complications that may aect healing and osseointegra-tion of the implants. A classication and nomenclature system for these exposures is useful for communication and recordkeeping. Clinical wound opening has been categorized by Tal69 (Box 31.1 and Fig. 31.34).Considering that spontaneous early exposures are complica-tions that can potentially lead to mucositis or peri-implantitis, Barboza and Caula72 proposed classication for spontaneous early AB C• Fig. . Titanium Dental Implant Allergy. (A) Facial eczema after implant placement. (B) Intraoral view of type IV hypersensitivity reaction. (C) Complete resolution after implant removal. (From Egusa H, Ko N, Shimazu T, etal. Suspected association of an allergic reaction with titanium dental implants: a clinical report. J Prosthet Dent. 2008;100:344-347.)AB• Fig. . Incision Line Opening (ILO). (A) Breakdown of the suture line leading to ILO. (B) Bone graft with ILO.Class 0: The mucosa covering the implant is intact.Class 1: A breach in the mucosa covering the implant is observed. Oral implant communication may be detected with a periodontal probe, but the implant surface cannot be observed without mechanically interfering with the mucosa.Class 2: The mucosa above the cover screw is fenestrated; the cover screw is visible. The borders of the perforation do not reach or overlap the borders of the cover screw.Class 3: The cover screw is visible. In some areas of the cover screw the borders of the perforation aperture overlap the borders of the cover screw.Class 4: The cover screw is completely exposed. • BOX 31.1 Clinical Dental Implant Wound Opening Categories 796PART VI Implant Surgeryexposure of submerged implants based on diagnostic methods and treatment modalities to prevent or intercept such complications. ey suggested that implants with spontaneous exposure should immediately be surgically exposed as early as possible to prevent mucositis. A healing abutment should be placed after the cover screw is removed.72 Morbidity Consequences of Incision Line Opening With Implants and Bone Graftinge resultant consequences of ILO can vary depending on the type of implant or bone-grafting procedure. For implant place-ment with good initial xation, primary closure is favored for AB CDE• Fig. . Incision Line Opening Classication. (A) Class 0 wound healing. (B) Class 1 wound healing. (C) Class 2 wound healing. (D) Class 3 wound healing. (E) Class 4 wound healing. 797CHAPTER 31 Dental Implant Complicationsone-stage surgery, with placement of a permucosal abutment. For bone augmentation procedures, primary closure is of paramount importance for clinicians when performing guided bone regenera-tion techniques and autogenous onlay grafting procedures. When ILO occurs during autogenous block grafting, there tends to be a greater potential for delayed healing, loss of graft into the oral cavity, and increased risk for infection.Exposureofnonresorbablemembranesaddsadditionalriskforinfection and unsatisfactory results. If guided bone regeneration is performed in conjunction with implant placement, ILO may also lead to loss of the implant. ILO most likely will result in a bacterial smear layer on the implant body, which may inhibit bone formation. Bone resorption resulting from infection may require implant removal. e same degree of ILO, without simultaneous implant placement, could possibly be managed and compensated for by bone expansion, use of slightly narrower implants, increased number of implants, and/or additional augmentation.In addition, ILO can negatively aect esthetic clinical out-comes. e placement of implants simultaneous with regenerative procedures adds the risk for a functional and esthetically compro-mised result. For multistage bone augmentation procedures, pri-mary soft tissue healing allows for the most predictable outcomes. Incision technique, ap design, soft tissue handling, and avoidance of transitional prosthesis pressure are key factors in avoiding ILO.Wound dehiscence may be associated with increased discom-fort and the need for closer monitoring. More postoperative appointments are required. ese are nancially nonproductive and negatively impact practice protability. Some patients may seek care or a second opinion because of loss of condence in the primary clinician. When ILO occurs, the clinician should be proactive in follow-up care and educating the patient on the com-plication consequences. Prevention of Incision Line OpeningGood Surgical Techniquee implant clinician should adhere to the following surgical principles to minimize and promote optimum wound healing and decrease the possibility of ILO.Incision in Keratinized Tissue. e primary incision should ideally be located in keratinized tissue whenever possible. is permits increased wound surface area and a resultant increase in vascularity to the incision. Not only does this reduce the initial intraoral bleeding, it also severs smaller blood vessels and reduces postoperative edema, which may add tension to the incision line. If there is 3 mm or more of attached gingiva on the crest of the edentulous ridge, the incision bisects this tissue. is places half of the attached gingiva width on each side of the incision. If there is less than 3 mm of attached keratinized tissue on the crest, the inci-sion is made more lingually so that at least 1.5 mm of the attached tissue is placed to the facial aspect of the implant. is concept is very important in the posterior mandible because attached tis-sue is needed to prevent tension and pulling from the buccinator muscle (Fig. 31.35).73 Broad-Based Incision Design. e apex or tip of the ap should never be wider than the base (e.g., diverge from incision base to the apex). is will maintain adequate vasculature that will prevent ischemic necrosis to the ap, decreasing the possibility of ILO. e length of the ap should generally not exceed twice the width of the base. In addition, the base of the ap should not have signicant pressure or be excessively stretched or twisted, which may compromise the blood supply (Fig. 31.36).74 Allow for Adequate Access. e ap should be large enough to provide adequate visualization of the surgical site and allow for the insertion of instruments to perform the surgical procedure. If the ap is too small, a retractor will not be able to maintain the apwithoutexcessivepressure.Excessiveretractionpressurewilllead to increased inammation, which may compromise the heal-ing of the incision line. Vertical Release Incision to Maintain Blood Supply and Decrease Tension on Flap. e blood supply to the reected ap should be maintained whenever possible. e primary blood supply to the facial ap, which is most often the ap reected for an implant or bone graft, is from the unkeratinized mobile mucosa. is is especially true where muscles of facial expression or functional muscles attach to the periosteum. erefore verti-cal release incisions are made to the height of the mucogingival junction, and the facial ap may be reected approximately 5 mm above the height of the mucogingival junction. Both of these inci-sion approaches maintain more blood supply to the facial ap. In addition, incisions and reection in the mobile alveolar mucosa increase ap retraction during initial healing, which may contrib-ute to ILO and may increase risk for scar formation and delayed healing of the incision line as a consequence of reduced blood supply.Vertical release incisions should not be made over bony promi-nences (e.g., canine eminence) because this will increase ten-sion on the incision line and may increase the possibility of ILO (Fig.31.37). • Fig. . Incision should always maintain attached tissue on the facial.• Fig. . Anterior papilla-sparing incision with broad-based design. 798PART VI Implant SurgeryMaintain Flap Margins Over Bone. e soft tissue ap design should also have the margins of the wound over host bone when-ever possible. is is especially important when approximating tissue over bone grafts or barrier membranes. e host bone pro-vides growth factors to the margins and allows the periosteum to regenerate faster to the site. e margins distal to the elevated ap should have minimal reection. e palatal ap and the facial tis-sues distal to the reected ap should not be elevated from the palatal bone (unless augmentation is required) because the blood supply to the incision line will be delayed. In addition, the unre-ected ap does not retract during initial healing, which could place additional tension on the incision line. e soft tissue reec-tion distal to the graft site may be split thickness to maintain peri-osteum on the bone around the incision line. is improves the early vascularization to the incision line and adhesion of the mar-gins to reduce retraction during initial healing. Clean, Concise Incision. A clean incision is made through the tissue in one direction with even pressure of the scalpel. A sharp blade of proper size (i.e., #15 blade) should be used to be make clean, concise incisions without traumatizing the tissue from repeated passes or strokes. Tentative strokes, especially in dierent planes, will increase the amount of damaged tissue and increase the amount of bleeding. Long, continuous strokes are preferable to shorter, inconsistent, and interrupted strokes.75Sharp dissection will minimize trauma to the incision line, which will result in easier closure. Care should be noted of vital underlying nerves, blood vessels, and associated muscles. Scalpel blades dull rather easily, especially when used on bone and tissue with greater resistance. e clinician should change blades when dulling is suspected to decrease tissue trauma. e incision should be made with the blade held perpendicular to the epithelial sur-face. is will result in an angle that produces square wound mar-gins that are easier to reorient during suturing and less likely for surgical wound necrosis to occur. Full-Thickness Reection and Ideal Flap Elevation. Ideally the ap should be full thickness and include the surface mucosa, sub-mucosa, and periosteum. e periosteum is necessary for heal-ing; the replacement of the periosteum in its original position will increase healing.Tissue elevation should be completed with extreme care. Metic-ulous handling is required to minimize trauma to the soft tissue. Proper use of appropriate tissue forceps, avoidance of excessive suctioning by the assistant, and “tie-back” sutures all contribute to improved ap management. Nonlocking tissue pick-ups, also called “thumb forceps,” are commonly held between the thumb and two or three ngers of one hand. Spring tension at one end holds the grasping ends apart until pressure is applied. ese for-ceps are used to hold tissues in place when applying sutures and to gently retract tissues during exploratory surgery. Tissue forceps can have smooth tips, cross-hatched tips, or serrated tips (often called “mouse’s teeth”). Serrated forceps used on tissues will cause less tissue damage than smooth surface forceps because the sur-geon can grasp with less overall pressure.Smooth or cross-hatched forceps are used to move dressings, remove sutures, and perform similar tasks.During ap elevation, elevators should rest on bone and not on soft tissue. Care should be exercised not to continuously suction the tissue because this may irritate and traumatize the tissue mar-gins.Useofvariable-suctiontipswithngertipcontrolcanhelpminimize tissue damage. After ap replacement, it is advantageous to apply pressure to the tissue for several minutes to minimize blood clot thickness and to ensure bleeding has stopped.Minimizing surgical operating time will directly benet soft tissues and will reduce the risk for infection.76 e tissue retrac-tors should be selected and placed in a position to prevent undue pressure on tissues. Maintaining the retractors on bone and not on thetissuewillminimizetraumatothetissue.Excessivepressureand tension on the tissue ap will impair blood circulation, alter the physiologic healing of the surgical wound, and predispose the wound to bacterial colonization (Fig. 31.38). Papilla-Saving Incisions. e interproximal soft tissue in sites next to adjacent natural teeth may be classied into three categories: (1) papillae have an acceptable height in the edentu-lous site, (2) papillae have less than acceptable height, or (3) one papilla is acceptable and the other papilla is depressed and requires elevation.When the interproximal papilla has an acceptable height, “papilla-saving” incisions are made adjacent to each neighboring tooth. e vertical incisions are made on the facial aspect of the edentulous site and begin 1 mm below the mucogingival junc-tion, within the keratinized tissue. Extending the vertical inci-sions beyond the mucogingival junction increases the risk for scar • Fig. . Full-thickness flap and reflection.• Fig. . Vertical release incisions to allow for tension-free closure. 799CHAPTER 31 Dental Implant Complicationsformation at the incision site. e full-thickness incision then approaches the crest of the edentulous site, leaving 1.0 to 1.5 mm of the interproximal papilla adjacent to each tooth. e vertical incisions are not wider at the base than the crestal width of tissue. is permits the facial ap to be advanced over the implant or short and adjacent to a permucosal extension at the conclusion of the procedure, with no voids at the incision line and primary closure. Hemostasis. Hemostasis is important for many reasons, such as providing a clean surgical eld for accurate dissection and ap elevation, along with decreasing trauma. Bleeding can occur from arteries, veins, or capillaries and may result in diuse, continuous oozing. Ideally complete hemostasis should be achieved before the closure of the wound. If not, the continuous bleeding or hema-toma will prevent the apposition of the surgical wound. ere are many mechanical, thermal, and chemical methods that may be used to achieve adequate hemostasis. Care should be noted that the use of active or passive hemostatic agents, along with elec-trocauterization of the wound margins, may decrease the normal physiologic healing of the wound margins and predispose the site to infection and possible wound dehiscence. If hemostatic agents are used (e.g., cellulose), they should be removed after hemostasis is accomplished because this may interfere with surgical wound healing. Prevent Desiccation of the Tissue. e tissues should be maintained in a moist environment without prolonged periods of desiccation. If drying of the tissues occurs, there is less likeli-hood that complete wound closure will occur. If the tissue margins become desiccated, periodic irrigations with sterile saline (0.9% sodium chloride) or a saline-moistened gauze may be used. Relieving Tissue (Tension Free). Excessiveaptensionisthemost frequent causative factor of ILO. is is best prevented by appropriate incision and ap design, the use of periosteal releas-ing incisions (PRIs), and blunt dissection (“tissue stretching”). Past techniques to expand tissue primarily used a more apical tis-sue reection and horizontal scoring of the periosteum parallel to the primary incision. Historically the vestibular approach by Brånemark allowed for optimal visualization of anatomic land-marks, suturing remote from the surgical area, complete tissue coverage, as well as predictable primary closure and healing.77 e postoperative disadvantages of this approach include distortion of the vestibule and other anatomic landmarks, edema, dicult suture removal, and cumulative patient discomfort.78 Langer and Langer79 documented the use of overlapping partial-thickness aps. is approach results in extension of the coronal aspect of the buccal or palatal ap, allowing primary intention closure around the site in an overlapping manner. is is usually eective for primary closure when less than 5-mm advancement of the ap is necessary.A submucosal space technique developed by Misch80 in the early 1980s is an eective method to expand tissue over larger grafts(greaterthan15×10mminheightandwidth)(Box 31.2).e utility of periosteal incision for gaining ap release was studied by Park etal.81 ey found that aps could be advanced up to 171.3% (>1.5 times longer than its original length) by two vertical incisions and a PRI under a minimal tension of 5 g, whereas one or two vertical incisions without PRI could advance the ap only 113.4% and 124.2%, respectively. ese results suggested that PRI can be predictably used to attain tension-free primary closure under a minimal pulling tension of aps (Fig. 31.39). Decreasing “Dead Spaces”Gentlepressureisappliedtothereectedsofttissueapsfor3to5 minutes. is pressure may reduce postoperative bleeding under the ap, which may cause “dead spaces” and delayed healing. Any stagnant blood under the ap is “milked” from under the soft tis-sue by gentle pressure. is also allows the brin formation from the platelets to help “glue” the ap to the graft site. Decrease InflammationSystemic corticosteroids or NSAIDs may be administered before and after surgery to decrease soft tissue edema because edema has been shown to contribute to ILO.  1. The full-thickness facial flap first is elevated off the facial bone approximately 5 mm above the height of the vestibule. 2. One incision with a scalpel, 1 to 2 mm deep, is made through the periosteum, parallel to the crestal incision and 3 to 5 mm above the vestibular height of the mucoperiosteum. This shallow incision is made the full length of the facial flap and may even extend above and beyond the vertical release incisions. Care is taken to make this incision above the mucogingival junction; otherwise the flap may be perforated and delay soft tissue healing. 3. Soft tissue scissors (e.g., Metzenbaum) are used in a blunt dissection technique to create a tunnel apical to the vestibule and above the unreflected periosteum. The scissors are closed and pushed through the initial scalpel incision approximately 10 mm deep, then opened slowly. 4. This submucosal space is parallel to the surface mucosa (not deep toward the overlying bone) and above the unreflected periosteum. The thickness of the facial flap should be 3 to 5 mm because the scissors are parallel to the surface. This tunnel is expanded with the tissue scissors several millimeters above and distal to the vertical relief incisions. 5. The submucosal space is developed and the flap is advanced the distance of the “tunnel” and draped over the graft to approximate the tissue for primary closure without tension. Ideally the facial flap should be able to advance over the graft and past the lingual flap margin by more than 5 mm. The facial flap may then be returned to the lingual flap margin and sutured. This soft tissue procedure is performed before preparing the host region for any type of bone grafting or augmentation around an implant. • BOX 31.2 Submucosal Space Technique153• Fig. . Tension-Free Closure. Facial flap can be pulled over the lin-gual flap by a minimum of 5 mm. 800PART VI Implant SurgeryTransitional and Interim Prosthesis DesignOcclusal forces applied to a removable prosthesis over a healing implant or graft site may also cause ILO of soft tissues and delay wound healing. Without appropriate adjustment, these forces can easily result in ILO by compressing the surgical area during function before suture removal. e potential for crestal bone loss is increased during any graft healing or around implants during stage I healing, which may lead to implant failure from early load-ing. Although use of such prostheses should be discouraged, other strategies to minimize or eliminate this possibility would include extensive relief of the intaglio surface, ange elimination, and use of tissue conditioners.Much more preferable provisional tooth replacement(s) would be either tooth or implant (transitional) supported (Fig. 31.40).Other examples of xed transitional prostheses would include the bonding of natural tooth crowns or denture teeth to the teeth bounding the edentulous space and modication of existing xed partial denture, that is, pontic shortening. Removable transitional prostheses,suchasanEssixretainerorSnap-OnSmileprosthesis,are frequently used because of their rigid support and resultant lack of pressure on the incision line. A resin-bonded xed restora-tion can also be fabricated to provide improved function, espe-cially when crestal bone regeneration is performed.e prosthesis may depress the interdental papillae of adja-cent teeth. As a result a resin-bonded xed prosthesis is fabricated for the extended healing, and a removable device may be used short term for cosmetic emergencies (if the prosthesis debonds) (Fig.31.41).When a resin-bonded restoration is used, the adjacent teeth are not prepared and the device is bonded to teeth below the centric occlusal contacts. e interdental papillae are often depressed after initial socket healing. is type of transitional restoration for the single-tooth implant has the multiple benets of being o the soft tissue drape, the developing bone augmented site, and the healing implant-bone interface.Several options to the resin-bonded device permit these goals. AnEssixapplianceisanacrylicshell,similartoableachingtray,thathas a denture tooth attached to replace the missing tooth. is pros-thesis is the simplest treatment for tooth replacement postsurgery.When an adjacent tooth requires a crown be added to the orth-odontic wire, a cast-clasp RPD with indirect rest seats, which prevents rotational movements on the surgical site, is an excellent option. Atraumatic Suture RemovalRemoving sutures too early or traumatically may result in ILO and cause delayed healing, leading to morbidity of the implant or bone graft. Normally nonresorbable sutures or extended absorbable sutures are removed within 10 to 14 days after surgery. Suture removal should include the following steps: 1. Patient rinses lightly with 0.12% chlorhexidine gluconate. 2. With tissue pick-ups, hold up the knot end of the suture and cut the suture closest to the tissue. Care should be exercised not to traumatize or irritate the surgical wound.3. Gentlypullthesutureoutwiththeknotoutsideofthetissue.Do not pull the knot through the tissue to remove.4. Havethepatientrinsewith0.12%chlorhexidine.Evaluateandmake sure the interim prosthesis does not impinge on the sur-gical wound. e adjacent tooth may be prepared and a canti-levered transitional xed partial denture with a pontic over the surgical site may be used. When the patient requires orthodon-tics, a denture tooth and an attached bracket may be added to the orthodontic wire. Management of Incision Line OpeningIn the dental implant literature there are two treatment recom-mendations discussed with respect to ILO. e rst is to allow the surgical wound to heal via secondary intention with the use of antimicrobials and hygiene measures. e second treatment modality is to resuture the opened surgical wound, which is not recommended by the author (Table 31.3).To allow the site to heal by secondary intention, there needs to be signicant discipline and patient cooperation for a successful outcome. is treatment technique is dictated by many variables, such as the health of the existing tissue, tissue thickness, location, age of the patient, and size of the dehiscence.For an incision line opening to heal correctly, strict post-op instructions and procedures must be adhered to by the clinician and the patient. First, the clinician should make sure that no external inuence may directly traumatize or delay the healing. If an interim prosthesis is being used, care should be exercised to minimize any direct contact with the incision line. e intaglio surface of the prosthesis over the incision line should be modied • Fig. . Essix Appliance.ABC• Fig. . Ideal Provisional Prosthesis. (A) Postsuturing image. (B) Snap-On Smile prosthesis. (C) Insertion of prosthesis. 801CHAPTER 31 Dental Implant Complicationsaccordingly to be concave, not convex. e stress bearing areas (i.e. Maxilla – horizontal palate and residual ridge, Mandible- buc-cal shelf) should be maintained to absorb the occlusal forces. In addition, the ILO should be locally cleaned with 0.12% chlorhex-idine. e patient should be placed on a strict recall, ideally seen every week for the rst month.e patient should be instructed to rinse non-vigorously with 0.12% chlorhexidine twice a day. Strict avoidance of smoking and alcohol use as this will delay healing. If an interim prosthe-sis is being used, no denture adhesive should be positioned over the ILO area. And lastly, the patient should be instructed to not evaluate the site, especially by pulling the lip up to inspect the area. is will stretch the incision line and most likely will result in further dehiscence (Box 31.3). Resuturing ProtocolResuturing is most often not recommended because it is an unpre-dictable technique and in some cases increases the amount of dehiscence. When attempting to resuture a fresh wound, usually the epithelium is thin and friable, which often leads to tearing of the incision line. is may result in a larger dehiscence or infec-tion. If completed, the margins of the tissue should be “freshened” withascalpeloradiamondbur.Greensteinetal.82 have recom-mended that, when the dehiscence is small and occurs within 24 to 48 hours, the clinician may immediately resuture the dehis-cence. Once the wound is large (2–3 cm) or the time elapsed is more than 2 to 3 days, it becomes more dicult for the margins of the wound to be excised and resutured. It is the author’s recom-mendation to be cautious with resuturing incision lines that may end up resulting in increased morbidity of the surgical wound (Fig. 31.42). Biomechanical ComplicationsScrew LooseningAbutment screw loosening has been shown to be associated with an approximately 6% of implant prostheses fabricated.83 Screw loosening is the most common implant prosthetic com-plication, accounting for approximately 33% of all post-implant prosthodontic complications.84 More recent studies indicate this Clinician 1. Relieve prosthesis to have no buccal flange and no contact on the surgical wound area. 2. Maintain stress-bearing areas on the prosthesis with the use of a tissue conditioner; however, material should be removed from the dehisced area. 3. Locally clean the dehiscence area with 0.12% chlorhexidine. 4. Employ closer observation of the patient to include recall appointments a minimum of once a week for the first month. Patient Instructions 1. Nonvigorous rinse with 0.12% chlorhexidine twice daily and plaque control. 2. Minimize the use of interim prosthesis. 3. No direct mastication on the area of dehiscence. 4. Avoid smoking and the use of alcohol. 5. Avoid peroxide and alcohol-based mouth rinses. 6. Avoid acidic foods. 7. Avoid inspection of dehiscent site (pulling on lip to see area). 8. Do not use any denture adhesive with the interim prosthesis. • BOX 31.3 Secondary Intention Protocol Treatment of Incision Line OpeningTREATMENTSurgical Procedure Early (<1 Week) Late (∼>3 Weeks)Implant:One stage Secondary intention protocol (resuture ONLY if favorable conditions)Secondary intention protocolTwo stage Secondary intention protocol • Removeoverlyingtissuewithtissuepunchburorscalpel• Placepermucosalextension(≈1 mm above tissue; higher extension may lead to excessive force on the implant) (Fig. 31.42)Bone Graft:Particulate graft Secondary intention protocol Secondary intention protocolBlock graft Secondary intention protocol • Checkformobilityofgraft• Reducesharpbonyedges• FreshenwoundedgeswithdiamondburMembrane:Collagen (regular) Secondary intention protocol Secondary intention protocolCollagen (extended) Secondary intention protocol Secondary intention protocol• TrimexcessmembraneabovetissuelevelwithscissorsAcellular dermal matrix (AlloDerm) Secondary intention protocol Secondary intention protocol• TrimexcessmembraneabovetissuelevelwithscissorsNonresorbable (cytoplast, titanium) Secondary intention protocol • Removemembraneifchronictissueirritationorinfection• Ideallyattempttomaintainforatleast6weeks TABLE 31.3 802PART VI Implant Surgerycomplication occurs in approximately 8% of single crowns, 5% of multiple-unit xed prostheses, and 3% of implant overdentures. De Boever et al.85 have shown that 12% of prostheses exhibit loosening within 3 years, whereas Chaar etal.86 have shown an incidence rate of 4.3% within 5 years and approximately 10% long term (5–10 years). Screw loosening may cause consider-able complications. A loose screw may contribute to crestal bone loss because bacteria are able to colonize and harbor in the open interface. When an abutment screw becomes loose on a cemented crown, the crown may need to be cut o the abutment to gain access to the abutment screw, which results in patient disappoint-ment and unproductive clinician time. If a loose abutment screw is not treated appropriately, fracture of the prosthesis, implant components, or the implant body may occur.EtiologyExternal Force Factors. External forces that act on a screwjoint greatly increase the risk for screw loosening. ese forces may be called joint-separating forces when related to screw loos-ening; however, they are the same forces that are risk factors for implant failure, crestal bone loss, and component fracture. When the external joint-separating forces are greater than the force holding the screws together (called clamping forces), the screw will become loose. e external forces from parafunction, crown height, masticatory dynamics, position in the dental arch, and opposing dentition are factors that can dramatically increase the stress to the implant and the screw joint. In addition, conditions that magnify or increase these factors are cantilevers, angled loads, andpoorocclusaldesigns.Externalforcesappliedtothejointsys-tem are important to account for when the aim is to decrease the incidence of screw loosening. e endurance limit of a material is the amount of force required to fracture the object when enough cycles are applied. e greater the force, the fewer cycles required before fracture occurs. It is the combination and relationship of both the amount of force and the number of cycles that is the cause of the screw loosening complication. Cantilevers/Increased Crown Height Space. One of the most common causative factors resulting in screw loosening is excessive continuous occlusal forces. e most common example occurs in prostheses with improper occlusal contacts. e greater the stress applied to the prostheses, the greater the risk for abutment screw loosening. A nonideal prosthetic design may potentiate the force applied. Cantilevers increase the risk for screw loosening because they increase the magnitude of forces to the implant system: there is a direct relationship between the length of the cantilever and force applied to the prosthesis.87 Any of these external forces applied to a cantilever will further magnify the joint-separating forces. For example, cantilevers on prostheses lead to uneven occlusal loads. Uneven occlusal loads cause repeated cycles ofcompression and then tension and shear of implant components. Screws are especially vulnerable to tensile and shear forces. Both of these are dramatically increased with cantilever forces or angled loads. Because the screw is an inclined plane, the continued vibra-tion causes it to unthread.e greater the range of external forces, the fewer the num-ber of cycles necessary before screw loosening. When an increased crown height space exists (poor crown/implant ratio), there is a resultant greater force applied to the screw. is usually results in a greater risk for screw loosening (or fracture). Boggan etal.88 demonstrated that the force that is applied to the screw is directly related to the crown height. e crown height acts as a vertical cantilever, which magnies the force on the abutment screw. Parafunction. Of all the external forces that cause screw loosening, the primary factor is parafunction related. A hori-zontal bruxing patient loads the implant crown with an angled force repeatedly. is increases the magnitude of force, cycles to fatigue failure, and the angle of the force that places shear on the interface. Abutment screw loosening can be expected in a patient with a severe bruxing habit. A parafunction patient increases the amount of force to the system while also increasing the number of cycles to the system.Hence fractures of porcelain and cement seals and also screw loosening or fracture are inevitable. When the adjacent natural teeth are mobile to lateral or angled forces, the rigid implant and implant crown may be overloaded. A heavy bite force occlu-sal adjustment, which allows the adjacent teeth to move before implant crown contact, is recommended to reduce the risk for overload. Continuous occlusal loads can have a cumulative eect on the preload, and the screw material may undergo deforma-tion.89 When the force exceeds the yield strength, plastic defor-mation occurs, and the screw begins to deform. is material deformation causes the screw to loosen and leads to potential fail-ure of the prosthesis.AB• Fig. . Resuturing Complication. (A) Two weeks postoperatively showing suture breakdown. (B) After resuturing, complete bone graft is exposed. This is why resuturing is not recommended. 803CHAPTER 31 Dental Implant ComplicationsScrew loosening is also aected by the amount of the force and thenumberofcycles,andissimilartofatigue.Externalmethodstolimit screw loosening include factors that reduce the biomechanical stress. ese include key implant positions (i.e., to distribute forces evenly), sucient number of implants (i.e., adequate surface area), passive prosthetic frameworks, and adequate occlusal schemes.90 Splinted Versus Nonsplinted Crowns. Screw loosening of abutment or prosthetic screws occurs more often on individual implant crowns than on crowns that are splinted together. For example, in a report for single molar replacement, the abutment screw-loosening rate was 40% during a 3-year period. When two splinted implants were used to replace the molar space, the screw loosening was reduced to 8%.91 e stress distribution of splinted prosthetic units results in less force applied to the screw system. Studies have shown that splinted implant-retained overdentures have far less screw loosening in comparison with xed prostheses.92 Crown/Abutment Not Fully Seated. If the abutment is not fully seated because of improper abutment placement, tissue impingement, or bone impingement, a poor distribution of force in the screw system will result, which leads to increased screw loosening. When the abutment is not fully seated and completely tightened, the prosthetic screw will be distorted, which leads to inadequate preload and subsequent screw loosening or fracture (Fig. 31.43). Insucient/Excessive Torqueing. When improper preload via the torqueing process is applied to the abutment screw, screw loosen-ing will often occur. is may be caused by either excessive or insuf-cient tightening of the abutment screw. An implant screw is similar to a bolt joint in engineering. ere is a preload (tightening force) placed on the screw, which develops a force within the screw. As the screw is tightened, it elongates, producing tension, which results in the implant screw acting like a spring. e preload stretch of the screw is maintained by frictional force, and the tension between the screw and the implant/abutment is termed a clamping force.When insucient preload is applied to the screw, there is insuf-cient clamping force, which ultimately leads to screw loosening, especially under occlusal loading. When excessive force is applied, the clamping force is easily released, and screw loosening will occur (Fig. 31.44). A B• Fig. . (A) Nonpassive or improperly seated screw-retained restorations may be distorted when seated into position when the prosthetic screw is threaded. The distortion of the superstructure causes stresses that are concentrated at the crestal bone level and may result in bone loss. (B) Radiographic image depicting incomplete seating of abutment, which predisposes prosthesis to screw loosening.• Fig. . Nonideal torque applied to the screw leads to a greater inci-dence of screw loosening. If the screw is not torqued sufficiently or over-torque occurs, insufficient preload will result, which will most likely result in screw loosening. The proper torque wrench and technique should be used according to the manufacturer’s specifications because implant systems have various recommended torque values. 804PART VI Implant SurgeryScrew Diameter. e diameter of the abutment screw may have a signicant eect on the amount of preload applied to the system before deformation occurs. e greater the screw diameter, the higher the preload that may be applied, which results in a greater clamping force on the screw joint. How-ever, the coping and prosthetic screws vary greatly according to the type, size, and material. e strength of the material increases by a power of 4 when the diameter of the screw dou-bles (a screw with twice the diameter is 16 times stronger). As a result, abutment screws loosen less often because they can take a higher preload compared with coping and prosthetic screws. Some companies oer similar diameters for abutment and prosthetic screws. As a result a similar clamping force may be used for either component. Screw Material. e composition of the screw is another factor that modies its performance. e composition of the metal may inuence the amount of strain in the screw from preload and the point of fracture, directly aecting the amount of preload that can be safely applied. Screw material and yield strength vary greatly when all other factors are similar (e.g., 12.4 N for a gold screw to 83.8 N for a titanium alloy screw xation).93e deformation or permanent distortion of the screw is the endpoint of the elastic modulus. Titanium alloy has four times the bending fracture resistance of grade 1 titanium. Abutment screws made of grade 1 titanium deform and fracture more eas-ily than the alloy. Titanium alloy is 2.4 times stronger than grade 4 titanium. As such, a higher torque magnitude can be used on the titanium alloy abutment screw and female component (found within the implant body), less on grade 4 titanium, less on grade 1 titanium, and the least on gold screws.e elongation of metal is related to the modulus of elasticity, which depends on the type of material, width, design, and the amount of stress applied. e material of which the screw is made (e.g., titanium alloy, titanium, or gold) has a specic modulus of elasticity. A prosthetic gold screw exhibits greater elongation than a screw made of titanium alloy but has a lower yield strength.Although the strengths of titanium grades are dramatically dif-ferent, the modulus of elasticity is similar for grade 1 to 4 tita-nium. Hence the strain of the abutment screw is similar with each grade of titanium, but the safety load relative to fracture is dif-ferent. Titanium alloy (grade 5) has a slightly higher modulus of elasticity. Although not clinically relevant to metal-bone osseoin-tegration, the titanium alloy screw should have a slightly higher preload value. is is not a consequence relative to permanent deformation or fracture because it is more than twice as strong as the other grades of titanium.e metal for the screwdriver used in the torque wrench is also important to consider. Stripping of the screw head prevents the clinician from tightening or removing the screw. Some manufac-turers fabricate the torque wrench driver out of titanium alloy, and the screw is made of gold or titanium. e concept is that the torque wrench will not deform the hexagon and will not strip, so the device lasts longer. However, this is not ideal. It is easier to replace the torque wrench driver than the abutment or prosthetic screw.From a clinical standpoint the receptor site for the torque wrench is also a feature of the screw head to consider. e screw head has a rotation feature, most commonly a hexagonal design. e more sides to the rotation feature, the more often the head will strip. A slot or triangular feature will strip less than a hexagon. Component Fit. In the science of machining metal compo-nents there is a range of dimensions that manufacturers use. For instance, an implant 4 mm in diameter may actually range from 3.99 to 4.01 mm. Likewise the abutment and prosthetic coping connection also has a range. As a result, if a smaller implant body hex dimension is mated with a larger abutment connection, the components may not ideally t together. Most implant manu-facturers allow for a mist range that results in the abutment or coping being able to rotate 10 degrees on the implant body. Components between the abutment and implant body may have a mist of 10 degrees in a rotational dimension, and horizontal discrepancies have been reported up to 99 μm.94,95 ese ranges are dierent with respect to each implant system. e more accu-rate the component t, the less force is applied to the abutment or prosthetic screw.e incidence of screw loosening is also a function of the accuracy of t of the at-to-at connection of the implant and abutment or prosthetic component. Implant abutment connec-tions or prosthetic connections with an unstable mating interface place undue stress on the screw that connects the components. Mechanical testing has demonstrated a direct correlation between the tolerance of the at-to-at dimension of the external hexa-gon and the stability of the abutment or prosthetic screw. Binon96 showed that a mean at-to-at range of less than 0.005 mm exists on the hexagon, and a at-to-at range of less than 0.05 mm for the entire sample would result in a more stable screw joint. Studies have shown plastic castable patterns, which can be highly inaccurate, to have a vertical mist as high as 66 μm.97 e same manufacturing conditions apply to impression transfer copings and analogs. Many manufacturers have a wider machining range (+ or − variance) for the prosthetic components to reduce the cost of manufacturing. When transfer copings and analogs are used in impressions and then to fabricate the prosthesis in the laboratory and the implants are splinted together, the prosthesis may not pas-sively seat.Many manufacturers recommend the use of plastic (nonmetal) burnout posts. Plastic burnout prosthetic copings cost less, but they exhibit much greater laboratory variance and poor t because of irregularities and settling of the superstructure. Besides cost, another advantage of a plastic burnout pattern for a coping is that one type of metal is used for the coping and superstructure, lessen-ing the risk for metal corrosion or separation between the coping and superstructure.A machined coping may be used to t the implant abutment more accurately to reduce settling. Some manufacturers suggest a titanium coping to reduce the risk for mist. However, oxides form on the titanium-machined coping surface and impair metal adherence when the prosthesis or abutment metal work is cast to the coping. Mechanical retentive features on the coping improve this metal-to-metal attachment. Laboratory studies demonstrate that an alloy-cylinder compatibility exists when noble-metal alloys are used rather than titanium for a superior metal-to-metal con-nection. A machine coping connection is still present, so it is supe-rior to the plastic components used to cast one metal.98 e risk of oxides forming between the coping and metal of the prosthesis is also reduced. Implant Design. e type and design of the dental implant has a signicant impact on screw loosening. As a general rule, most implant bodies have an antirotational feature for the abutment con-nection. e most common designs are an external hexagon, an internal hexagon, a Morse taper, and a Morse taper with threads. 805CHAPTER 31 Dental Implant ComplicationsFactors that aect the abutment screw connection and screw loosening include the height (or depth) of the hexagon and the platform diameter. Boggan etal.88 studied the inuence of design factors on the mechanical strength and quality of t of the implant abutment interface. Whereas failure mode for static test samples was bending or deformation of the abutment screw, fracture of the abutment screw was the common failure mode for the fatigue test samples. e static failure load was greater for the external hex implants of 1 mm in height, compared with implants with an internal hexagon of 1.7 mm. e larger-diameter implant had the greatest static load before failure.88 As the hexagon height (or depth) increases, the load on the abutment screw decreases. Like-wise, as the diameter of the implant platform increases, the force on the abutment screw decreases. Reduction of the lateral load (P) on the abutment screw is crucial to prevent the load on the screw to be beyond the yield strength of the material.e height (or depth) of the antirotational hexagon is directly related to the force applied to the abutment screw with any lat-eral load. Because the crown is connected to the abutment and the abutment rests on the implant platform, a lateral force on the crown creates a tipping force on the abutment. is tipping force is resisted by the hexagon height or depth, the platform, and the abut-ment screw. When the arc of rotation is above the hexagon height, all of the force is applied to the abutment screw. For the hexagon height to be above the arc of tipping forces, the hexagon height must be at least 1 mm for a 4-mm-diameter implant. Yet many implant manufacturers feature a hexagon height of only 0.7 mm, so almost all of the force is directed to the abutment screw, increasing the occurrence of screw loosening and fracture (Fig. 31.45).edierencebetweenexternal(EC)versusinternalconnec-tions (IC) has been well documented. Studies have shown that the incidencerateassociatedwithECimplantswas18.3%atameanof 5.3 years (217 of 1183 restorations; maximum, 59.9%).99,100 e complication rate with internal connection (IC) implants was 2.7% at a mean of 4.5 years (142 of 5235 restorations; maximum, 31.6%).101,102 Other studies have shown the external hex to have a signicantly higher incidence of screw loosening than the inter-nalhex (MA-EC,15.1%; Zr-EC,6.8%;MA-IC, 1.5%;Zr-IC,0.9%).103e platform dimension on which the abutment is seated is also an important factor in screw loosening. Larger-diameter implants, with associated larger platform dimensions, reduce the forces applied to an abutment screw and change the arc of dis-placement of the abutment on the crest module. For example, in a report by Cho etal.,104 abutment screw loosening over a 3-year period was almost 15% for a 4-mm implant diameter but less than 6% for the 5-mm implant diameter (Fig. 31.46). Screw Versus Cement Retained. When evaluating the pros-thesis type (cement versus screw), studies have shown screw retained (8.5%) had a much higher incidence of screw loosening in comparison with cement retained (3.1%). ese complications have a greater incidence with screw-retained restorations com-pared with cement-retained restorations because cement-retained restorations are more passive and have less strain on the implant system.105 Although a cement-retained restoration is more com-mon, screw-retained restorations are indicated when low-prole retention is necessary on a short abutment or when the implant bodies are more than 30 degrees from each other and splinting is required to restore the patient.In addition, a screw-retained prosthesis has the advantage of less chance of tissue irritation because of the high incidence of retained cement with a cement-retained prosthesis. Screw loos-ening and partially unretained restorations are common compli-cations of nonpassive castings. e more passive the t on the implant abutment for screw retention and the more controlled the occlusal forces, the more secure is the prosthesis. e repeated compressive and tensile forces from nonpassive castings under occlusal loads cause vibration and loosening of the screw com-ponents. Accuracy in design and fabrication of the metal super-structure are determining factors for the reduction of forces at the implant abutment and implant-bone interface. Passive screw-retained restorations are more dicult to fabricate than passive cement-retained restorations. When the screw is threaded into position, the superstructure may distort, the implant may move within the bone, or the abutment screw may distort. e distor-tion of the superstructure and implant system may reach a level such that a 500-μm original gap may not be detectable.106 As a result the casting may appear to t the implant abutment for screw retention. However, the superstructure, bone, and components do not bend beyond their elastic limit, and compression, tensile, and shear forces are placed on the bone-implant interface.107 e bone must remodel to eliminate these forces. If the forces are beyond physiologic or ultimate strength limits, resorption of the 2182162142120.7 0.75 0.8 0.85Height (mm)Fs (N)0.9 0.951.0• Fig. . The higher (or deeper) the antirotational hexagon component (x component on the graph), the less the force applied to the abutment screw (Fs) on the y axis. A 0.7-mm hexagon height is standard in the industry and was used first by Nobel Biocare. A 1-mm hexagon height has less risk for screw loosening because the force on the screw is decreased.3002802602402202001801603 3.544.5Diameter (mm)Fs (N)5 5.56• Fig. . To reduce forces on the abutment screw, the platform diam-eter of the implant is more important than the hexagon height. The larger the diameter (x-axis), the less the force applied to the screw (y axis). 806PART VI Implant Surgerybone-implant interface occurs. As a result, greater crestal bone loss has been associated with nonpassive castings. Creep (a constant force applied over time on a material) or fatigue also can contrib-ute to fracture of the components over time because of a constant load or cyclic load frequency. Anatomic Location. e location of the prosthesis in the oral cavity is also a signicant factor in the incidence of screw loosen-ing. Sadid-Zadeh etal.108 showed a signicant incidence dierence with respect to anatomic locations, anterior (12.8%; 51 of 398 restorations) and posterior positioning (4.8%; 144 of 2972 resto-rations). However, when evaluating internal connection implants, they had an associated higher incidence of screw loosening in the posterior region (4.3%) than the anterior region (0.7%). PreventionDecreased Force. Because of the directional relationship between force and screw loosening, the evaluation, diagnosis, and modication of treatment plans related to stress conditions are of considerable importance. After the clinician has identied the source of excessive force on the implant system, the treatment plan is altered in an attempt to minimize the negative impact on the longevity of the implant, bone, and nal restoration. Prosthetic Design. e prosthetic design may be altered to minimize the possibility of screw loosening. Ideal implant place-ment in the key implant positions should be adhered to.Cantilevers should be eliminated or reduced, especially when high occlusal forces are present. In addition, implant protection principles should be adhered to, including reduction of cuspal inclines of the prosthesis (decreased cusp height), decreased occlu-sal table, and no lateral contacts, especially in the posterior. Ideal Preload. e ideal torque force on an abutment screw varies by manufacturer and may range from 10 to 35 N-cm. is preload is determined by many variables, including the screw material, screw head design, abutment material, abutment surface, and possible lubricant. To reduce the incidence of screw loosening, the abutment screw should be torqued by the following protocol: 1. Light nger-tighten with driver (∼10 N-cm). 2. Maximum nger-tighten with driver (∼20 N-cm). 3. Implant screw should be torqued to the manufacturer’s speci-cations (∼30-35 N/cm). 4. After 5 to 10 minutes, the screw should be retorqued to the same manufacturer’s specications.NOTE: For cases of expected increased force, the implantscrew may be retorqued a third time after 30 to 60 days. Screw-Tightening Sequence. When screw-tightening a mul-tiunit xed implant prostheses, a proper sequence and technique is crucial to obtain the correct torque. e torque should be applied incrementally among all screws so that not one screw is tightened fully. is is based on the fact that a multi-unit prosthe-sis is unlikely to be “completely” passive. A nonideal tightening sequence will lead to either an insucient or excessive amount of torqueplacedontoaspecicscrewthread.Undertorquewillleadto insucient clamping force and lack of ideal stretching of the screw. is will most often lead to screw loosening. Overtorque will lead to permanent deformation of the screw, which may lead to screw fracture. Settling Eect. Settling is a term used to describe the eect of various implant parts wearing and tting closer together. Minor irregularities on or within a casting that incorporates the top of an abutment or screw can cause slight elevation of the casting or the screw head. Over time, micromovement wears down the irregularities, and the parts t closer together. However, this set-tling relaxes the preload force on the prosthetic screw and is more likely to cause screw loosening. is embedment relaxation or loss of preload has been shown to be approximately 2% to 10% of the initial preload within the rst few seconds or minutes after tightening. is is the reasoning for the earlier protocol to include a second retorque after 5 to 10 minutes to regain the lost preload due to settling.109 Torque Under Moist Conditions. Studies have shown when placing and torqueing abutment screws, more accurate torque val-ues result under wet conditions versus dry.110 Saline may be used to lubricate the screw before placement of preload to maximize the accuracy of the preload. Wider Implant Bodies. e use of wider implant bodies results in decreased force on the screw. Graves et al.111 have shown increasing implant size from 3.75 to 5.0 mm results in 20% greater strength, whereas increasing implant size from 3.75 to 6.0 mm increases the strength by 33%. TreatmentWhen confronted with a mobile prosthesis, it is important to determine whether the mobility is a result of screw loosening or the actual implant being mobile (implant failure). Box 31.2 illus-trates a technique to determine the cause of the prosthesis move-ment (Fig. 31.47).Implant Movement. Mobility of the implant body indicates failure of the implant and necessitates immediate removal. A radiograph may reveal a circumferential radiolucency. e site should then be re-evaluated after adequate healing for the need of bone grafting, implant placement, or change in prosthetic treat-ment planning. Abutment Screw MovementOption 1. Removing a cemented crown from a mobile abut-ment is very challenging with conventional crown removal tech-niques (e.g., crown bumper). e impact force that is applied to the mobile crown is dissipated because of the loose screw. is may result in damage to the internal threads of the implant body. In addition, when an implant crown margin is subgingival, it is often dicult to obtain access for the crown remover. In poorer bone densities, overzealous use of a crown remover may result in loss of the bone-implant interface. Option 2. e safest and most predictable treatment option to treat abutment movement is accomplished with making an occlusal access and transforming the cement-retained crown into a screw-retained crown (Fig. 31.48).Following are the steps for completing this procedure:1. Evaluate and determine the location and angulation of theimplant abutment screw (buccal-lingually and mesial-distally). An intraoral radiograph is often helpful. 2. With a round diamond bur (≈#8 round), access is made through the occlusal surface to remove the abutment screw (i.e., central fossa: posterior teeth and lingual aspect of crown in anterior teeth). 3. After the screw is located, the screw is engaged with the appro-priate hex driver, reverse-torqued, and the screw is removed. 4. Discard old screw and place new screw. 5. Torque to the manufacturer’s specications with ideal protocol. 6. Cover access hole with ller (polytetrauoroethylene) and opaque composite.In situations where the access hole is through the facial aspect of the prosthesis (i.e., anterior crowns), the crown will need to be removed and a new crown fabricated. Care should be exercised 807CHAPTER 31 Dental Implant Complicationswhen cutting the crown o because in most cases it is dicult to determine the cement location (Fig. 31.49).is may result in sectioning the crown too deep, causing dam-age to the abutment, abutment screw, or implant body. A safer method includes the earlier technique (access with screw removal) with fabrication of a new prosthesis. If the abutment remains x-ated to the prosthesis, the prosthesis can be easily removed by gen-tly heating the prosthesis with a Bunsen burner. Screw FractureEtiologye causative factor most likely to induce screw fractures is bio-mechanical stress to the implant system. e biomechanical stress leads to partially unretained restorations or fatigue, which is directly related to an increased amount of force. Prosthesis screw fracture has been shown to occur with a mean incidence rate of 4% with a range of 0% to 19%. Abutment screw fracture is directly related to the screw diameter, with larger-diameter screws fracturing less often, and a mean incidence rate of 2% and a range of 0.2% to 8% (Fig. 31.50).112 PreventionImmediate Treatment of Loose Screw. If an abutment screw is determined to be mobile, immediate treatment is recommended. e longer the period that force is applied to a mobile prosthesis, the greater the chance the abutment screw will be deformed and possibly fracture. e loose screw follows a fatigue curve that is related to the number of cycles and the intensity of the repeated forces. TreatmentExplorer Removal. e easiest method to remove a screw is to rotate the screw counterclockwise with a sharp explorer tip. A BC D• Fig. . (A and B) Checking buccal-lingual mobility of the prosthesis with a mirror handle. (C and D) Palpation of buccal and lingual cortical plates to evaluate the presence of pain. 808PART VI Implant SurgeryA BCD E FG• Fig. . Loose Screw Removal Technique. (A) Occlusal access is made with a #8 round diamond bur. (B) Screw is easily removed with implant driver. (C) Access needs to be large enough to allow for screw removal. (D) Chlorhexidine irrigation of the internal threads. (E) A new screw is torqued into posi-tion according to the manufacturer’s recommendations. (F) Sterile polytetrafluoroethylene is placed in the access hole after final torque. (G) Opaque composite placed into access. 809CHAPTER 31 Dental Implant ComplicationsBecause a loose screw has no preload, the fractured compo-nent remains passive in the implant body. If the screw has been deformed or debris has been introduced between the screw and the implant body, this technique may not be successful (Fig. 31.51). Ultrasonic/Cavitron Device. If debris is present between the threads, an ultrasonic or Cavitron device may be used. e vibration (≈20,000–30,000 rpm) will usually dislodge the debris, and the screw can then be removed via the explorer method. Round Bur (205LN). A very small round bur or 205LN can be used in a slow-speed handpiece or AS123 screwdriver. e tip of the bur is placed at the seam of the fractured screw and abutment (implant). As the bur spins clockwise, the friction placed on the screw makes it turn counterclockwise, and the screw unthreads. Inverted Cone Bur (~33½ Bur). With an inverted cone bur in a high-speed handpiece (ideally electric handpiece in reverse), gently touch the top of the screw. is will usually result in the screw being extruded from the implant body. Care should be exercised to not touch the implant body with the bur because this will result in damage to the implant body threads. With this technique, always use a throat pack to prevent loss (Fig. 31.52). Slot the Top of the Screw. A slot 1 mm deep is made through the center of the screw with a high-speed handpiece and a very narrow ssure bur (or 33½ bur). A small screwdriver is then used to unthread the screw. Be careful using this tech-nique because the bur may inadvertently perforate the side of the implant body. ere is no predictable method to repair the implant body if this occurs. e patient should be informed that implant failure may result as a consequence of this tech-nique (Fig. 31.53). Manufactured Retrieval Instruments. Multiple retrieval kits are on the market that are used to remove fractured screws. ese are usually specic for the type of implant body type (internal, external, trilobe, etc.) (Fig. 31.54). AB• Fig. . (A) Most commonly in the maxillary anterior the access may need to be made through the facial surface. (B) Care should be exercised in cutting cement-retained crowns off because the abutment screw may be irreversibly damaged.AB• Fig. . (A and B) Fractured screws that usually occur from occlusal overload. 810PART VI Implant SurgeryAB• Fig. . Explorer Technique to Remove Broken Screw. (A and B) The screw may be easily removed if preload is lost by using the explorer in a counterclockwise direction.AB• Fig. . (A) Inverted cone (33½ bur) with handpiece. (B) The fractured screw is lightly tapped in the center of the screw, which will usually dislodge the screw. A throat pack should be used, and care should be exercised to not touch the internal walls of the implant. 811CHAPTER 31 Dental Implant ComplicationsNeurosensory Impairmente iatrogenic injury of any of the branches of the trigeminal nerve is a major concern in implant dentistry. As the number of implants being placed each year keeps increasing, along with a greater number of clinicians performing the procedures, the inci-dence of nerve impairments will most likely continue to increase. e reported incidence of such nerve injuries after dental implant procedures is highly variable (0%–44%) in the literature.113 Stud-ies have shown that approximately 73% of doctors who perform implant surgery have experienced postoperative nerve complica-tions.114 Libersa et al.115 evaluated transient versus permanent nerve injuries after implant placement and reported a permanent injury 75% of the time (Fig. 31.55).When a nerve injury occurs, it is paramount the dental implant clinician be able to recognize the type and extent of injury, and provide the most appropriate postoperative care. Traumatic and iatrogenic nerve complications may involve total or partial nerve resection, crushing, thermal, stretching, or entrapment injuries. e resulting sensory decits may range from a nonpainful, minor loss of sensation (hypoesthesia), to a more permanent and severe debilitating pain dysfunction (dysesthesia). e sensory complica-tions from a nerve injury will usually result in an overall decreased quality of life for the patient and potential long-standing psycho-logical problems.116 Not only do these complications aect the patient, the clinician is often confronted with patient dissatisfac-tion, embarrassment, and possible medicolegal implications.In the eld of oral implantology today the clinician must have a thorough understanding of the cause, prevention, and treatment of neurosensory impairments. A postoperative classication and guidelines for the diagnosis and management of neurosensory decits have been developed by the author, which is dependent on the history, type, and nature of the injury.Specific Anatomic Areas Susceptible to Nerve InjuryInferior Alveolar NerveNerve impairment to the inferior alveolar nerve (mental nerve) is a common clinical complication with major medicolegal implica-tions. Because of its anatomic location, the mental nerve is the most common nerve to be damaged via implants or bone graft procedures. Trauma usually occurs from placement of implants directly into the foramen or into the inferior alveolar canal in the posterior mandible. Sensory nerve injury may result in altered sensation, complete numbness, and/or pain, which may interfere with speech, eating, drinking, shaving, or makeup application and lead to social embarrassment.e mandibular division of the trigeminal nerve (cranial nerve V) exits the skull base via foramen ovale and then divides into an anterior and posterior division. e anterior division of the mandibular nerve has mainly motor branches that innervate the temporalis, lateral pterygoid, and masseter muscles. e posterior division of the mandibular nerve is mainly sensory, which pro-vides branches including the lingual nerve, inferior alveolar nerve, and auriculotemporal nerve. e inferior alveolar nerve divides into two terminal branches, the mental and incisive nerves.117 e mental nerve courses anteriorly until it exits through the mental foramen, which is sensory to the soft tissues of the chin, lip, and anterior gingiva. e incisive nerve continues anterior and inner-vates the mandibular anterior teeth.Most nerve injuries that occur in relation to dental implant surgery involve the inferior alveolar nerve. Accurately determin-ing the exact location of the inferior alveolar nerve as it courses through the body of the mandible is imperative to avoid neuro-sensory disturbances secondary to implant placement. Histologi-cally this inferior alveolar nerve consists of connective tissue and neural components in which the smallest functional unit is the individual nerve ber. e inferior alveolar nerve bers may be either myelinated or unmyelinated. e myelinated nerve bers are the most abundant; they consist of a single axon encased indi-vidually by a single Schwann cell. e individual nerve bers and Schwann cells are surrounded by the endoneurium, which acts as a protective cushion made up of a basal lamina, collagen bers, and endoneurial capillaries. Lingual NerveWithin the infratemporal fossa the lingual nerve divides from the posterior division of the mandibular nerve (V3) as a terminal branch. As the lingual nerve proceeds anteriorly, it lies against the medial pterygoid muscle and medial to the mandibular ramus. It then passes inferiorly to the superior constrictor attachment and courses anteroinferiorly to the lateral surface of the tongue. As it runs forward deep to the submandibular gland, it terminates as the sublingual nerve.AB• Fig. . (A) Slot the top of the screw. A slot is made in the screw with a high-speed handpiece and narrow fissure bar. A screwdriver is then used to unthread the screw. (B) Use of an ultrasonic scaler to loosen debris between the screw and the internal threads of the implant. 812PART VI Implant SurgeryABCDE• Fig. . Salvin Implant Rescue Kit. (A) Place guide on implant and hold with stabilizing handle. Insert drill into implant handpiece. Set motor to REVERSE at 1000 to 1250 rpm and 50 to 70 N-cm torque. (B) Drill in REVERSE using “up and down” motion to prepare 1- to 2-mm deep dimple into top of broken screw. (C) Insert tap into implant handpiece; set motor to REVERSE at 70 to 80 rpm and 50 to 70 N-cm torque. (D) Insert tap into the 1- to 2-mm dimple in the top of the broken screw. Use the tap in REVERSE to remove broken screw. (E) Screw removed. (Courtesy Salvin Dental Specialties, Inc., Charlotte, N.C.)AB• Fig. . (A and B) Implant-induced nerve impairment. 813CHAPTER 31 Dental Implant Complicationse lingual nerve is sensory to the anterior two-thirds of the tongue, oor of the mouth, and lingual gingiva. It also contains visceral aerent and eerent bers from cranial nerve VII (facial nerve) and from the chorda tympani, which relays taste informa-tion. With the prevalence of second molar implants, care should be taken to note the possible position of the lingual nerve on the medial ridge of the retromolar triangle, where it courses anteriorly along the superior lingual alveolar crest, which is slightly lingual to the teeth.118Due to the lingual nerve’s variable anatomic location, it may be iatrogenically traumatized during various implant surgical pro-cedures.Usuallythelingualnerveisnotdamagedfromtheactualosteotomy preparation of implants unless the lingual plate is perfo-rated. is sensory nerve is most likely traumatized during soft tis-sue reection during implant placement in the second molar area or incision/reection over the retromolar pad for bone graft procedures.In addition, the lingual nerve can suer damage from lingual ap retraction and inferior alveolar nerve blocks. Studies have shown that lingual nerve impairment after nerve blocks occurs twice as often as inferior alveolar nerve damage.119 is is most likely due to the fact the lingual nerve is most commonly unifas-cular at the site of the injection. Sensory damage to the lingual nerve may cause a wide spectrum of complications ranging from complete anesthesia to paraesthesia, dysesthesia, drooling, tongue biting, change in taste perception, and change in speech pattern. Nasopalatine Nervee incisive canals fuse and form a common Y-shaped canal that exits lingual to the central incisor teeth (incisive foramen or inci-sive fossa). e nasopalatine nerve passes through these canals and provides sensation to the anterior palate. ese nerves (also termed incisive nerves) terminate at the nasal oor and enter the oral cavity via the incisive canal, which is underneath the incisive papilla. To prevent trauma to these nerves, ideal presurgical plan-ning of implant placement in the maxillary incisor region should be carefully evaluated.In the literature, many authors have advocated removing the contents of the nasopalatine canal and grafting with a high success rate.120 Although this nerve is often aected by the placement of implants or bone grafting in the incisor region, sensory distur-bances are rare. Nerve damage reported in the literature caused by complete removal121 or ap surgery122 is of short duration. is is most likely due to cross-innervation of the greater palatine nerve on the anterior palatal area. Anterior Superior Alveolar Nervee anterior superior alveolar nerve branches from the infraorbital canal on the lateral face. is small canal may be seen lingual to the cuspid and is denoted as the canalis sinuosus. e canal runs forward and downward to the inferior wall of the orbit and after reaching the edge of the anterior nasal aperture in the inferior turbinate, it follows the lower margin of the nasal aperture and opens to the side of the nasal septum. Studies have shown that in approximately 15% of the population, this canal is approximately 1 to 2 mm in diameter. e canals present as a direct extension of the canalis sinuosus and may be clinically relevant when greater than 2.0 mm (Fig. 31.56).123e canine pillar region is a key implant position for dental implants. Care should be exercised to evaluate for the presence of neurovascular bundles. Insertion of implants in approximation to the canal may be problematic because this may lead to a soft tissue interface and failure of the implant and temporary or permanent sensory dysfunction and possible bleeding issues. However, sig-nicant sensory impairments are rare because of cross-innervation. Many clinicians are unaware of the canalis sinuosus and may misdi-agnose this radiolucency as apical pathology of the maxillary cuspid. Infraorbital Nervee infraorbital nerve emerges from the infraorbital foramen and gives o four branches: the inferior palpebral, external nasal, internal nasal, and the superior labial branches, which are sensory to the lower eyelid, cheek, and upper lip. e inferior palpebral branches sup-ply the skin and conjunctiva of the lower eyelid. e nasal branches A B• Fig. . Canalis sinuosus. (A) Anatomic variant that may lead to the placement of implants into the canal, leading to a soft tissue interface. Cross-sectional cone beam computed tomographic image show-ing location in center of the residual ridge. (B) Three-dimensional view of the canalis sinuosus. 814PART VI Implant Surgerysupply the lateral nose soft tissue and the movable part of the nasal septum, and the superior labial branches supply the skin of the cheek and upper lip. Normally the average distance of the inferior border of the orbital rim to the infraorbital foramen is 4.6 to 10.4 mm.Impairment of the infraorbital nerve may be very traumatic to patients. Damage to branches of the infraorbital nerve usually will result from retraction-related trauma (neuropraxia). Procedures involving the maxillary cuspid-bicuspid area are most susceptible to injuries. Anatomic variants of the infraorbital foramen have been shown to be up to 14 mm from the orbital rim. is is most likely seen in elderly female patients with extensive alveolar atrophy. Etiology of Nerve InjuriesMost implant-related nerve impairments are the direct result of poor treatment planning and inadequate radiographic evaluation. Trauma to associated nerves in the oral cavity occurs when the implant clinician is not aware of the amount of bone or does not know the location of nerve canals or foramina. e preoperative evaluation and assessment are crucial to determine the amount of available bone in approximation to nerve anatomy. A CBCT examination is most commonly used for the three-dimensional planning in these areas.Neurosensory impairment injuries may result from a wide array of intraoperative and postoperative complications. For example, nerves may be mechanically injured by indirect or direct trauma via retraction, laceration, pressure, stretching, and transection. ermal trauma may cause inammation and secondary ischemia injuries with associated degeneration. And lastly, peripheral nerves have been shown to be susceptible to chemical injuries, where the nerve is directly traumatized by chemical solutions.Administration of Local AnesthesiaAdequate local anesthesia is paramount for successful dental implant surgery and stress reduction protocol. However, although rare, the use of nerve blocks may result in trauma to various branches of the trigeminal nerve. e exact cause of local anesthe-sia nerve damage is unclear, and various theories such as injection needle trauma, hematoma formation, and local anesthetic toxicity have been discussed.Although the true incidence is dicult to quantify because of reporting diculties, studies have shown permanent injury occurs in approximately 1 in 25,000 inferior nerve blocks. Most patients do recover fully without decits, with full recovery in 85% of patients with complete remission in 8 to 10 weeks.124Damage From Injection Needle. Complications resulting from needle trauma are likely the most common theory on why nerve injury results after administering nerve blocks. First, it is not uncommon for the tip of the needle to become barbed (damaged) when contacting bone. Stacy etal.125 showed that 78% of needles became barbed after initial injection, increasing the possibility of damaging the nerve. Two-thirds of the needles developed outward-facing barbs, which have been shown to rupture the perineurium, damage the endoneurium, and cause transection of nerve bers. e lingual nerve has been associ-ated with the highest percentage of nerve impairment cases as a result of an anesthetic injection (∼70%).126 Because of the lingual nerve’s anatomic location, it is predisposed to nerve inju-ries because it is commonly contacted when using the ptery-gomandibular raphe as an injection landmark because of the nerve being positioned shallow in the tissue (∼3–5 mm from the mucosa).127 Hematoma. e anesthetic needle may also cause damage to the epineurial blood vessels, which may result in hemorrhage-related compression on the nerve bers. e accumulation of blood may lead to brosis and scar formation, which may cause pressure-related trauma.128 e extent of impairment to the nerve is directly related to the amount of pressure exerted by the hematoma and recovery time of the axonal and connective tissue damage. Anesthetic Toxicity. If the anesthetic is injected within the fas-cicular space, chemical irritation and damage may occur. Studies have shown articaine to comprise 54% of mandibular nerve block injuries,129 and it is 21 times more likely to cause injury in com-parison with other nerve injuries.130 eories concerning articaine toxicity include the high concentration of articaine solution and the increased resultant inammatory reaction.131 Lidocaine has been shown to be the least toxic anesthetic, followed by articaine, mepivacaine, and bupivacaine.132 Chemical trauma from local anesthetics has been shown to cause demyelination and axonal degeneration of nerve bers.134 Soft Tissue ReflectionInjury to nerves and nerve bers may occur during the reec-tion, retraction, or suturing of the soft tissue. is is most noted when the mental nerve is dehisced or exposed on the mandibular ridge. Special caution should be exercised when making incisions over these areas because complete transection injuries may occur from incisions through the nerve or foramen. Stretching injuries (neuropraxia) may occur from excessive retraction, so care should be noted as to the proximity of neural vital structures within the retracted tissue. A common stretching injury occurs with the infraorbital nerve, especially when implants or bone grafting are being performed in the canine and bicuspid region. Complete transection of the nerve may result from attempting to reduce the tissue tension over the surgery ap without regard to the anatomic location of the nerve (Fig. 31.57).Implant and Implant Drill Traumae surgical drilling for implant placement may result in a direct or indirect neurosensory impairment.Trauma. Direct trauma from surgical drilling may occur from overpreparation of the osteotomy site or lack of knowledge of the true bur length. e implant clinician must know and understand the true length of the surgical burs used in the osteotomy site prepa-ration. For many surgical drill systems, the marked millimeter gauge lines inscribed on the shank of the drills most often do not include the cutting edge of the drill and do not correspond to the actual depth of the drill. Most surgical implant drills have a sharp, V-shaped api-cal portion to improve their cutting eciency and allow adequate depth of drilling. e V-shaped apical portion of the drill (termed the Y dimension in engineering) is often not included in the depth measurements of the commercial drills and may measure as much as 1.5 mm longer than the intended depth. erefore the clinician may inadvertently drill deeper than anticipated because of the drill design.In addition, overpreparation may occur, especially in less dense bone. e implant clinician should use the initial implant oste-otomy twist drill as a gauge for bone density type and for an evalu-ation of the position of the surgical drill relative to the mandibular canal or vital structure. In implant dentistry today the popular-ity of immediate placement implants has been associated with an increase in drilling-related trauma. To gain primary stability, most immediate implant osteotomy sites require drill preparation and implant placement apical to the extraction site. When placing implants in the mandibular premolar area, violation of the canal 815CHAPTER 31 Dental Implant ComplicationsAB• Fig. . Periosteal release of the tissue to obtain tension-free closure, which may cause nerve injury. (A) The use of a #15 blade to release the periosteal fibers. (B) Blunt dissection to release tissue with Metzenbaum scissors.may occur, causing nerve damage. erefore in this anatomic area, immediate implant placement is not recommended unless ade-quate bone is available below the root apex. e following subsec-tions describe the various types of surgical drill trauma that may lead to a neurosensory impairment. Thermal Trauma. e surgical drill may cause a nerve impair-ment from thermal damage even though the surgical drill does not violate the mandibular canal. Most commonly this is the result of insucient irrigation, which leads to overheating the bone. e associated thermal trauma may lead to nerve impairment via bone necrosis from overheating the bone during preparation. Nerve tis-sue has been shown to be more sensitive to thermal trauma than bone (osseous) tissue. In the literature, excessive temperatures have been reported to produce necrosis, brosis, degeneration, and increased osteoclastic involvement.30 To minimize this com-plication, the bone density should be evaluated preoperatively via CBCT examination, tactile evaluation, and location. In harder bone densities (e.g., D1 and D2), special care should be exercised in reducing the possibility of overheating the bone (see Chapter27). Partial Penetration. e surgical drill may also cause direct trauma to the neurovascular bundle by penetrating the mandibu-lar canal or mental foramen. e neurosensory impairment will be directly related to the specic nerve fascicles that are damaged. Normally the vein and artery, which are positioned more supe-riorly than the nerve, will be damaged when penetration of the canal results. is indirect trauma leads to nerve damage from the excessive bleeding (hematoma), as well as thermal and chemical injuries from the penetration into the canal. Transection. e most severe type of nerve injury, with the lowest probability of regeneration, is when the implant drill transects the canal. In a true transection the nerve is completely severed. When this occurs, repair and regeneration of the trau-matized nerve are highly variable. Complete transection of the nerve occurs when surgical error involves the preparation of an osteotomy too deep because of inaccurate measurements or slip-page of the handpiece. is type of injury results in the most severe of response, a total nerve impairment (anesthesia) and neuroma formation. Usually this type of nerve injury resultsin a complete anesthesia and retrograde degeneration, result-ing in possible future dysesthesia.135 e extent of neurosensory impairment is directly related to the extent of fascicle injury and is dependent on the time the implant is left to irritate the nerve bers (Fig. 31.58). ABCD• Fig. . Drill Impingement Trauma. (A) Encroachment: even though the surgical drill is short of canal, thermal damage and bone necrosis (brown/green) result in nerve damage. (B) Partial penetration (hematoma): the surgical drill partially penetrates the superior aspect of the canal, resulting in bleeding and hematoma formation. (C) Partial penetration (lac-eration): the surgical drill penetrates deeper into the canal, which results in laceration of nerve fibers. (D) Transection: the surgical drill may penetrate the entire canal, leading to complete transection of the nerve fibers. 816PART VI Implant SurgeryImplant Encroachment on the Mandibular Canal. Injuries to vital nerve structures caused by implant positioning are most com-mon in the posterior mandible. ese injuries may be caused by direct trauma (mechanical) and indirect trauma or infection (pres-sure). Placement of an implant into or near the mandibular canal is associated with many types of neurosensory impairments (Fig. 31.59). When an implant is too close to the mandibular canal, a compression or secondary ischemia injury may occur. To prevent these complications, the implant clinician should always adhere to a 2.0-mm safety zone of the implant in proximity to the canal or mental foramen. Studies have shown that implant pressure on the canal occurs with increasing stress as the bone density decreases.136 Khaja and Renton showed that placing an implant too close to the canal may induce hemorrhage or deposition of debris into the canal,causingischemiaofthenerve.Evenremovingtheimplantor repositioning may not alleviate and decrease pressure-related symptoms. Additional studies have shown the presence of post-operative severe pain after implant placement in close approxima-tion to the canal, resulting in chronic stimulation and debilitating chronic neuropathy.137 Partial Penetration Into the Mandibular Canal. Placement of the implant body into the mandibular canal is associated with a highdegreeofmorbidity.Eventhoughthesensorynervefasciclesare usually inferior to blood vessels within the canal, a partial penetration may result in an injury that is usually related to the bers that are damaged. is is why in some clinical situations the implant is directly within the canal; however, no neurosensory symptoms exist.In addition, implant placement into the canal may cause hema-toma formation (severing of the inferior alveolar artery or vein), leading to a pressure-induced nerve impairment. Infection. Placement of implants in approximation to the canal may cause neurosensory impairments via peri-implant infections. Infectious processes after implant placement may result from heat generation, contamination, or prior existence of bone pathology. is may lead to spread of infection that may extend into the neural anatomy. Case reports have shown nerve impairment issues resulting from an implant infected by chronic peri-implantitis.33 Mandibular Socket Grafting. After mandibular tooth extrac-tions, grafting into the socket may eectively expose the inferior alveolar nerve to socket medicaments. is may lead to chemi-cal neuritis, and if the irritation persists, an irreversible neuropa-thy may occur (Fig. 31.60). In addition, care should be exercised when removing pathology and granulation tissue from extraction sockets in close proximity to the nerve canal (type 1 nerve).138 Overzealous curetting of the socket apex may lead to direct trau-matic injury of the canal. Delayed Nerve Damage (Canal Narrowing). Nerve damage may result even when ideal implant placement is performed (>2.0 mm from the nerve canal). Shamloo etal.139 reported an implant placement case in which the implant body resulted in compression and bone to be forced into the superior aspect of the mandibular canal (canal narrowing). is led to delayed healing and remodeling within the canal and resulted in exces-sive narrowing of the canal, with compression of the nerve bers. e narrowed aspect of the canal was shown be approxi-mately 0.2 mm, with an average diameter in the nonaected sites being approximately 3.2 mm.139 e nerve impairment (paresthesia and anesthesia) occurred 2 years after implant placement surgery. ABCDE• Fig. . Implant Impingement Trauma. (A) Encroachment: even though the implant body is short of the canal, thermal damage may occur from overheating the bone. (B) Bone fragments (trabeculae) may be pushed apically, resulting in a pressure necrosis nerve injury. (C) Par-tial penetration (hematoma): the implant body may partially penetrate the superior aspect of the canal, resulting in bleeding and hematoma forma-tion. (D) Partial penetration (laceration): the implant body may penetrate deeper into the canal, which results in laceration of nerve fibers. (E) Tran-section: the implant body may penetrate the entire canal, leading to com-plete transection of the nerve fibers. 817CHAPTER 31 Dental Implant ComplicationsNerve Healing PhysiologyAfter nerve injury, there exist two phases of healing: degeneration and regeneration.Degenerationere are two types of nerve degeneration: segmental degenera-tion and Wallerian degeneration. Segmental demyelination occurs when the myelin sheath is damaged and causes a slowing of the conduction velocity, which may prevent the transmission of nerve impulses. e resulting eects will clinically be paresthesia, dys-esthesia, or hyperesthesia. e second type of degeneration is termed Wallerian degeneration, in which the axons and myelin sheath distal (away from the central nervous system) to the injury undergo complete disintegration. e axons proximal to the site of injury (toward the central nervous system) undergo less degen-eration, but many nodes of Ranvier (periodic gaps in the myelin sheaths of axons that facilitate the rapid conduction of nerve impulses) are aected. Wallerian degeneration usually occurs after complete transection of the nerve and results in a dysesthesia type of symptoms. RegenerationUsuallyregenerationoccursimmediatelyafternerveinjury.eproximal nerve area sprouts out new bers that grow at a rate of 1.0 to 1.5 mm/day. is will continue until the site innervated by the nerve is reached or blocked by brous connective tissue, bone, or an object (e.g., dental implant). During the regenera-tion process, new myelin sheaths form as axons increase in size. In some situations the continuity of the Schwann cells is disrupted, and connective tissue may enter the area. e growth may nd an alternative path, or it may form a traumatic neuroma, which is usually characterized by signicant pain. Studies have shown that the administration of steroids may minimize the formation of neuromas, especially the administration of high doses within the rst week of nerve injury (Fig. 31.61).140 Neurosensory Deficit Classificationere are two widely accepted classications of nerve injuries. In 1943 Seddon141 postulated a three-stage classication, which was later reclassied by Sunderland in 1951 into ve dierent subclas-sications. ese nerve injury classications are described by the resultant morphophysiologic type of injury, which is based on the time course and amount of sensory recovery (Fig. 31.62).Neuropraxia, or rst-degree injury, is characterized by a con-duction block with no degeneration of the axon or visible damage oftheepineurium.Usuallythistypeofinjuryisconsistentwithstretching or manipulation (reection of tissue) of the nerve bers, which results in injury to the endoneurial capillaries. e degree of trauma to the endoneurial capillaries will determine the mag-nitude of intrafascicular edema, which results in various degrees ofconductionblock.Usuallyresolutionofsensationandfunctionwill occur within hours to weeks.Axonotmesis (second-, third-, or fourth-degree injury) consists of degeneration or regeneration axonal injuries. e injury clas-sication depends on the severity of axonal damage. is type of injury involves the endoneurium, with minimum disruption to the perineurium and epineurium. e most common types of injury are traction, stretching, and compression, which can lead to severe ischemia, intrafascicular edema, or demyelination of the nerve bers. Initially complete anesthesia is most common, ABC• Fig. . Post-extraction Site. (A) Care should be taken when grafting an extraction site in close approximation to the inferior alveolar nerve. (B) A curette should be used with caution because direct damage to the nerve may occur. (C) Grafting in close approximation to the canal may lead to nerve trauma. 818PART VI Implant Surgerywhich is followed by paresthesia as recovery begins. Improvement of the related sensory decits occurs within approximately 2 to 4 months, with complete recovery usually within 12 months. In some cases painful dysesthesias are possible, with resulting neu-roma formation.Neurotmesis (fth-degree injury) is the most severe type of injury, resulting from severe traction, compression, or com-plete transection injuries. Initially patients exhibit anesthesia, followed by paresthesia with possible dysesthesia. A very low probability of neurosensory recovery exists, with immediate referral for a neurosurgical evaluation recommended.142 e axon and encapsulating connective tissue will lose their con-tinuity. ere is usually complete loss of motor, sensory, and autonomic function. Neuroma formation is common if tran-section has occurred.e literature involving peripheral nerve injuries is vast, with a signicant variation in the nomenclature used to describe the asso-ciated clinical signs and symptoms. Neurosensory impairments are classied from complete numbness to severe pain of the facial soft tissues to the intraoral anatomy. Because of these decits, severe complications result for the patient and the clinician. A thorough understanding of the associated classications and denitions is necessary (Tables 31.4 and 31.5).To standardize the nomenclature concerning nerve injuries, the International Association for the Study of Pain reduced sen-sory impairment into three categories: anesthesia, paresthesia, and dysesthesia.42 Anesthesia is characterized by the complete lack of “feeling,” which is usually consistent with complete transection of the nerve. is type of altered sensation is most severe because anesthesias are the most dicult and unpredictable to treat, with a high incidence of neuroma formation. Paresthesia is dened as an altered sensation that is not unpleasant. It is usually character-ized as a “pins and needles” feeling. Within the paraesthesia cate-gory, many subcategories exist, including hypoesthesia (decreased sensitivity to stimulation), hypoalgesia (decreased response to a stimulus that is normally painful), and synesthesia (sensation in an area when another is stimulated). Dysesthesias are classied asanalteredsensationthatisunpleasant.Usuallypainisassoci-ated with this type of impairment, which may be spontaneous or mechanically evoked. Subcategories include hyperalgesia (pain-ful response to nonpainful stimuli), hyperpathia (delayed or pro-longed painful response), anesthetic dolorosa (pain in an area that Segmentaldemyelination(after neuropraxia)Walleriandegeneration(after axonotmesis)AxonaldegenerationHealed nerve Walleriandegeneration(after neurotmesis)NeuromaformationDegeneration Normal regeneration Abnormal healing• Fig. . Normal and abnormal nerve responses (degeneration, regeneration) to nerve injury. (From Hupp JR, Tucker MR, Ellis E. Contemporary Oral and Maxillofacial Surgery. 6th ed. St. Louis, MO: Mosby; 2014.) Conduction blockEndoneuriumPerineuriumEpineuriumAxonal discontinuityAxonal + endoneurialdisruptionPerineurial rupturefascicle disruptionNerve trunkdiscontinuityAxonNeurapraxia IAxonotmesis II – III – IVNeurotmesis VWallerian degeneration =Classification of Nerve InjurySunderlandSeddon• Fig. . Seddon/Sunderland Neurosensory Impairment Classification with description of nerve dam-age. (From Ellenbogen RG, Sekhar LN, eds. Principles of Neurological Surgery. 3rd ed. Philadelphia: Saun-ders; 2012.) Neurosensory Impairment Classication and Injury ResponseSunderland Seddon Description Causes Responses Recovery RateI Neurapraxia Temporary interruption of nerve trans-mission (conduction block)• Nervecompression• Edema• Hematoma• Minorstretching• Thermal• Neuritis• ParesthesiaComplete (fast—days to weeks)II Axonotmesis Endoneurium, perineurium, and epi-neurium remain intact; some axonal degeneration may occur• Nervecompression• Traction• Hematoma• Partialcrush• Edema• Stretching• Paresthesia• Episodic• DysesthesiaComplete (slow—weeks)III Disruption of axon and connective tissue (endoneurium), causing disorganized regeneration; Wallerian degeneration occurs• Crush• Puncture• Severehematoma• Stretching• Paresthesia• DysesthesiaVariable (slow—weeks to months)IV Damage involves entire fascicle; axonal, endoneurium, and perineurium changes occur; the epineurium is intact; scar tissue formation• Fullcrush• Extremestretching• Highthermal• Directchemicaltrauma• Hypoesthesia• Dysesthesia• NeuromaformationUnlikelyV Neurotmesis Complete transaction or tear of the nerve with amputation neuroma forming at injury site• Complete• Transection(overprepara-tion with implant drill)• Anesthesia• Intractablepain• NeuromaNone TABLE 31.4 820PART VI Implant Surgeryis anesthetized), causalgia (persistent burning pain), and allodynia (pain in response to a stimulus that usually does not provoke pain). TreatmentNerve Impairment at Time of SurgeryDuring surgery, if known traction or compression of the nerve trunk has occurred, the topical application of dexamethasone may beusedtominimizedecits.Uponremovalofthesurgicaldeillorimplant from the mandibular canal, 1 to 2 mL of the intravenous form of dexamethasone (4 mg/mL) is topically applied into the osteotomy site (Fig. 31.63). is direct steroid application will reduce neural inammation and may enhance recovery from neu-rosensory decits. Studies have shown no morbidity associated with the topical application of glucocorticoids at the injury site, and postsurgical recovery has also been shown to improve signi-cantly.143 No bone grafting or implant should be placed that may lead to irritation of the traumatized nerve bers. Postoperative Nerve ImpairmentWhen a neurosensory decit occurs postoperatively, a compre-hensive sensory evaluation must be completed. is initial exami-nation is used to determine whether a sensory decit exists, to quantify the extent of injury, document a baseline for recovery, and determine whether referral for microneurosurgery is indicated.Step 1: Clinical Assessment. e implant clinician must rst determine whether a neurosensory decit exists by mapping the area of decit. is diagnostic examination consists of objective and subjective ndings to determine the extent of impairment, to use as a baseline for future evaluation, and to determine when referral for surgical intervention is required. e subjective clinical sensory tests involve nociceptive and mechanoceptive examinations. Nocicep-tive tests trigger a variety of autonomic responses that result in the subjective experience of pain. Mechanoceptive tests use mechanical stimuli to trigger sensory neurons that elicit various responses such as touch, position, and motion (Table 31.6 and Fig. 31.64).Clinical Examination Complications. ere exist many inherent problems with relying on the credibility of the patient’s subjective responses. Because there may exist a high degree of false-positive and false-negative results, clinicians should use clear and concise instruc-tions when administering these tests. For instance, when administer-ing the “directional movement” test, the clinician should complete this test on the contralateral side rst so the patient understands the technique and response. e results of the subjective clinical exami-nation will depend on good communication between the implant clinician and the patient, with the outcome of the results related to the patient’s perceived interpretation and how to relate their Description of Neurosensory Impairment Decits154Paresthesia Abnormal sensation that is not unpleasantAnesthesia Total loss of feeling or sensationDysesthesia Abnormal sensation that is unpleasantAllodynia Pain due to a stimulus that does not normally provoke painHyperpathia Abnormally painful reaction to a stimulusCausalgia Persistent burning painAnesthesia dolorosa Pain in an area that is AnesthetizedHyperesthesia Increased sensitivity to stimulationHyperalgesia Increased response to a stimulus that is normally painfulHypoesthesia Decreased sensitivity to stimulationHypoalgesia Decreased response to a stimulus that is normally painfulSynesthesia Sensation felt in an area when another area is stimulated TABLE 31.5AB• Fig. . (A) Dexamethasone 4 mg/mL (Mylan, Canonsburg, Pa.). (B) One to two milliliters of dexa-methasone placed into the osteotomy site. 821CHAPTER 31 Dental Implant Complicationsperceptions. In addition, the tests should be administered with the patient’s eyes closed, so as to minimize the possibility of incorrect responses. Step 2: Radiographic Evaluation/Removal or Repositioning of the Implant. A thorough and comprehensive radiographic exami-nation should be completed, including (ideally) a CBCT radio-graph. If the implant (or bone screw) is in close approximation of the nerve bundle, removal or repositioning should be completed. Care should be exercised in “backing” the implant out (reposi-tioning farther from the nerve) because trauma to the nerve may still be present from hematoma formation or pressure from can-cellous bone crushed into the neural space. In addition, backing the implant out may lead to the implant being positioned unde-sirably because of lack of interocclusal space for the restoration (i.e.,too coronally positioned). In these cases the implant should be removed and the osteotomy site irrigated with 4% dexametha-sone (1–2 mL). No graft materials should be added to the oste-otomy site because they may interfere with the reinnervation and repair of the nerve trunk.144 Step 3: Pharmacologic Intervention. Immediately after the nerve is traumatized, the inammatory process begins with the activation of cytokines and inammatory mediators. ese inammatory mediators will contribute to the development of nerve trauma by activating the neurons and their nociceptors.145With any type of nerve impairment, corticosteroids or non-steroidal anti-inammatory agents should be used immediately. Studies have shown that the use of systemic adrenocorticoste-roids (e.g., dexamethasone) minimizes neuropathic symptoms after nerve trauma if administered in high doses within 1 week of injury.146 It has been advocated that a tapering dose of a cortico-steroid for 5 to 7 days after trigeminal nerve injury is benecial.147 Dexamethasone (∼8 mg) is specically recommended because of its greater anti-inammatory eects, in comparison with other corticosteroids such as methylprednisolone or prednisone. Addi-tional pharmacologic agents include antidepressants, neurologic drugs, antisympathetic agents, and topical agents.In addition, cryotherapy (ice packs) should be applied to the paraneural tissues for the rst 24 hours and then episodically for the rst week. Cryotherapy has been shown to be benecial in minimizing secondary nerve injury from edema-induced com-pression, decreasing the metabolic degeneration rate of trigeminal ganglion cells, and slowing potential neuroma formation.148 Addi-tional physiologic agents include transcutaneous electric nerve stimulation, acupuncture, and low-level laser therapy. Step 4: Possible Referral. In certain situations patients may need to be referred in a timely manner to a practitioner experienced in nerve injury assessment and repair. e decision and timing to refer should be based on the patient’s symptoms and the type of injury, together with the experience of the implant dentist in treating nerve injuries.Usuallysucienttimeisgivenforneurosensoryrecovery.Incases of dysesthesia, anesthesia, or known nerve transection, prompt surgical intervention may allow for the best chance of neurosensory recovery. Early, aggressive treatment has been shown to minimizepossible transition to chronic refractory neuropathies (Table 31.7).149 Step 5: Follow-Up Care. Follow-up care should always be a component of the treatment of a patient with nerve impairment. e interval between appointments is determined by the extent andtypeofnerveinjury.Usuallyafterthe1-weekpostoperativeappointment, patients are seen every 2 weeks with mapping and documentation of the decits noted. Surgical Intervention. Surgical repair is indicated in some cases of neurosensory impairment. In general, early treatment is crucial to success and decreased morbidity. Microneurosurgical procedures include direct nerve repair via primary anastomoses of the two severed nerve ends for transection injuries. For nerve splits, reestablishment and proper alignment of nerve stumps will allow for the best chance to correct regeneration of the damaged nerves. Fractured ImplantAlthough rare with today’s dental implants, fractured implant bodies may cause signicant problems for both clinicians and patients. Dental implant fractures may be one of the major causes of late implant failures and may include possible medicolegal issues. Studies by Goodacre et al.150 relate the risk for implant body fracture in the early to intermediate period for implants 3.75 mm in diameter to be approximately 1%, the abutment screw frac-ture risk at 2%, and the prosthetic screw risk at 4% (Fig. 31.65).Etiologye incidence of implant body fracture dramatically increases when force conditions are greater. Cantilevers, angled loads, and para-function increase the risk for fracture. e risk for fracture also increases over time. Typical mechanical failures are due to either Diagnostic Testing for Neurosensory ImpairmentDiagnostic Test DescriptionNociceptivePin pressure (A-delta, C-fiber)Determination of feeling from pin pressure using a blunted explorer. A normal response (distinct sharp pain) is a positive sign of feeling (in relation to an unaffected area) with no pain. If no feeling is present in comparison with an unaffected side, the area is termed hypoalgesia. If an exaggerated response is noted in relation to an unaffected side, the area is termed hyperalgesia.Thermal discrimi-nation (warm: A-delta, cold: C-fibers)Ice chips or ethyl chloride spray and a heated mirror handle (warmed to 43°C) are used to determine the patient’s ability to feel cold and hot.MechanoceptiveStatic light touch Cotton tip applicator with the patient’s eyes closed to test tactile stimulation by gently touching the skin and determining the thresh-old of the patient (A-beta afferent axons).Directional movement: Soft brush is used to determine the patient’s ability to detect both sensation (A-beta and A-alpha axons) and direction of movement. The soft brush is swiped from left to right, as well as in the reverse direction.Two-point discrimi-nationWith the patient’s eyes closed, the patient’s ability to discriminate varying (myelinated A-alpha fibers) distances between two points is determined using a caliper. The normal values vary significantly, with the average being approximately 5 mm.73 TABLE 31.6 822PART VI Implant Surgerystatic loads or fatigue loads. Static load (i.e., one load cycle) failures cause the stress in the material to exceed its ultimate strength after one load application. Fatigue load failures occur if the material is subjected to lower loads but repeated cycles of that load. e endur-ance limit or fatigue strength is the level of highest stress a material may be repetitively cycled through without failure. e endur-ance limit of a material is often less than half of its ultimate tensile strength. erefore fatigue and ultimate strength values are related, but fatigue is a more critical factor, especially for patients with para-function because they impose higher stress magnitude and greater cycles of load. Dierent materials have varying degrees of resistance to repeated loading and subsequent fatigue-related failures. e fatigue strength of titanium alloy (Ti-6Al-4V) is four times greater (and safer) than grade 1 titanium and almost two times greater than grade 4 titanium. Long-term fracture of implant bodies and com-ponents may be dramatically reduced with the use of titanium alloy rather than any grade of commercially pure titanium. PreventionA titanium alloy implant should ideally be used to reduce the pos-sibility of implant body fracture. Parafunctional habits should be addressed with occlusal guards, narrow occlusal tables, no lateral contacts, and an ideal occlusal scheme. ABCDE F• Fig. . Sensory Testing. (A) Mapping out deficit with eyeliner. (B) Light touch with cotton applica-tor. (C) Directional test with brush. (D) Two-point discrimination using calipers. (E) Thermal test with mirror handle. (F) Pinpoint tests with explorer or dull needle. 823CHAPTER 31 Dental Implant Complications Neurosensory Impairment Treatment ProtocolNEUROSENSORY DEFICIT TREATMENT ALGORITHMSPostsurgery Documentation Pharmacological Intervention Treatment Referral∼48 hours Three-dimensional radiographic examination (cone beam computed tomography); neurosensory examinationCorticosteroids: (dexamethasone 4mg)2 tabs a.m. for 3 days1 tab a.m. for 3 daysImplant evaluation: • Removalandrepositionif impingement within the mandibular canal • Nobonegrafting • Cryotherapy(1week)None, unless unfamiliar with neurosensory testing1 week Neurosensory examination (testing should be continued every 2 weeks thereafter)High-dose NSAIDs (600–800 mg ibuprofen TID)Palliative Refer to oral surgeon or neuro-surgeon if: • Knownnervetransection • Dysesthesia • Completeanesthesia8 weeks Neurosensory examination NSAIDs PRN Palliative IF NO SIGN OF IMPROVEMENT, refer to OMFS or microsurgeonNSAID, Nonsteroidal antiinflammatory drug; OMFS, Oral and Maxillofacial Surgery Foundation; PRN, as needed; TID, twice daily. TABLE 31.7ABCDE• Fig. . Fractured Implants. (A) Midimplant fracture. (B and C) Implant neck fracture. (D) Crestal implant fracture. (E) Clinical image of implant neck fracture. 824PART VI Implant SurgeryTreatmente ideal treatment for a fractured implant includes the removal and possible replacement of the implant. Alternative treatments include modication of the prosthesis to not include the implant and possible modication of the fractured implant (cementable abutment). Explantation of Dental ImplantsIn some situations a failing implant or the position of the implant necessitates removal with reinsertion in an ideal position. e fol-lowing are possible reasons why dental implants may need to be removed:• Mobilityoftheimplant• Extensiveboneloss• Chronicpain• Advancedperi-implantitis• Fracturedimplant• MalpositionedimplantPotential ComplicationsTaking an aggressive approach to removing an implant may lead to further bone loss and jeopardize the future site for reimplan-tation. Because an implant does not contain a periodontal liga-ment, placing too much force and pressure on it may lead to buccal or lingual plate failure. Loss of bony plates or excessive bone loss may result in the need for extensive bone augmentation in the future. Treatmente removal of dental implants is dictated by the location, amount of bone present, type of implant, and presence of mobility.Mobile Implante loss of the bone-implant integration necessitates immediate removal because infection and further loss of bone may result. Incertain cases the implant may migrate within tissue spaces or may be swallowed or aspirated.Countertorque Ratchet. is technique involves placing an abutment or an engaging extraction tool into the implant and reverse torqueing the implant counterclockwise. is technique is usually atraumatic, however caution should be exercised to not use excess force as this may lead to bony plate fracture. Convention Extraction Techniques. is method uses con-ventional forceps and elevators, and should be used only with minimal luxation to prevent possible fracture of the buccal or lin-gual plate. After removal, all soft tissue should be removed from the implant site before grafting or reimplantation. A throat pack should always be used to minimize the possibility of aspiration of the implant upon removal. Nonmobile ImplantA partial or fully integrated implant is usually more problem-atic and can be in some cases very dicult to remove. Conven-tional extraction techniques should never be used because they may lead to signicant bone loss or fracture. If a nal crown and abutment is present, they should be removed to allow for easier access.Countertorque Ratchet. is technique involves placing an abutment or an engaging extraction tool into the implant and reverse torqueing the implant counterclockwise. is should be used only in poorly dense bone (∼maxilla). Care should be exercised in higher-density bone because damage or fracture of the implant body or adjacent bone may occur with this type of removal technique. e existing bone density is the most critical factor which aects the ease of implant removal via the counter-torque technique.Implant Type. In general, an internal hex implant is easier to remove via the countertorquemethod.Externalhex implants,because they engage coronal to the implant body, are more dicult to remove because of lack of leverage. Trilobe inter-nal connections, especially those with smaller diameters, have been shown to fracture when greater than 45 N-cm of torque is applied.151 Care should be exercised to prevent fracturing the implant on removal. Implant read Shape. ere are generally four types of implant thread designs: buttress, square, V-shaped, and reverse buttress. e square thread shape has the highest bone-implant contact and will be the most dicult to remove via the counter-torque method. Implant Body Design. A tapered implant design will be easier to remove than a square implant design. e thread depth and sur-face area decrease in the apical area, which minimizes the torque force necessary for removal. In addition, less chance of fracturing the bony plates exists. Antirotational Design. Some implant designs contain a vent or opening, usually at the apical end, that will allow for bone growth integration. is will complicate the removal of a par-tially or fully integrated implant. A trephine or surgical bur technique may be indicated in the removal of these types of implants. Reverse Screw Techniques. A reverse screw removal drill is usually inidcated when the internal aspect of the implants (threads) are damaged or when the countertorque method is unsuccessful.Caution should be exercised with smaller-diameter internal implants (∼3.0 mm) because fracture of the implant body may occur (Fig. 31.66). High-Speed Burs. e use of a high-speed bur is a fast, ecient technique to remove an integrated implant. Ideally a tapered surgical bur (extra long: 700 XXL) is used to minimize bone removal. e bur is used 360 degrees around the implant to a depth of half to three-fourths the length of the implant to be removed. Copious amounts of saline should be used to mini-mize thermal damage and the possibility of osteomyelitis. is helps to maintain bone and minimize damage to vital structures. After removal, the implant site should be irrigated to remove any particles (Fig.31.67). Piezo Surgical Units. A piezo surgical unit uses piezoelectric vibrations to cut bone tissue. By adjusting the ultrasonic frequency of the unit, it is possible to remove hard tissue while leaving soft tissue untouched by the process. Studies have shown that piezo units cause less soft tissue damage compared with other extraction techniques.151 Trephine Burs. Trephine burs are barrel-shaped burs that are available in various diameters. e bur selected should be slightly larger than the implant crest module because too large of a trephine bur will result in excessive bone removal. Too small of a trephine may result in implant body particles being removed and becoming embedded in the implant site. Copious amounts of saline should 825CHAPTER 31 Dental Implant ComplicationsABC• Fig. . Reverse Screw Technique. (A) Implant with more than 50% bone loss. (B) Implant insertion tool inserted into implant. (C) Reverse torque with hand ratchet.be used to minimize thermal damage and the possibility of osteo-myelitis. If the apex of the implant is in approximation to a vital structure, the trephine bur should not be used at the apex to avoid vital structure damage.After the implant is removed, the implant site should be irri-gated to remove any retained titanium particles (Fig. 31.68). Combination of Techniques. In some cases it is prudent to remove bone half to three-fourths the length of the implant (using a trephine, piezo, or high-speed bur), together with the use of conventional extraction techniques or the countertorque method.AB• Fig. . (A) 700XXL bur. 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