Intraoral Autogenous Bone Grafting










1054
38
Intraoral Autogenous Bone
Grafting
C. STEPHEN CALDWELL AND CARL E. MISCH
T
reatment plans in implant dentistry in the past used existing
bone volume to determine the location and type of implant
and restorations were adapted to accommodate irregulari-
ties related to implant locations. In abundant bone (Division A),
endosseous root form implants were inserted; in bone of moderate
width (Division B), blade implants were placed; and in inadequate
height of bone (Division C−h), subperiosteal implants were the
treatment of choice.
Treatment planning has dramatically changed. e nal pros-
thesis type and design is rst determined, followed by determin-
ing the ideal implant positions, numbers, and sizes. e available
bone is often inadequate to provide the foundation required for a
predictable treatment plan. As a consequence, bone grafting has
become a more frequent solution for achieving long-term success.
In addition to the biomechanical and functional needs signi-
cant esthetic considerations need to be included in planning a case.
Bone grafting is often indicated to allow placement of an implant
in the proper location for an ideal esthetic result. In addition,
the soft tissue drape often requires enhancement in the esthetic
zone as the bone foundation sets the tone for the soft tissue drape.
erefore when ideal crown contours (FP-1) and soft tissue are
desired, bone augmentation is an important aspect of the treat-
ment plan. As a result of biomechanical-based foundations and
esthetic desires, a primary diagnostic consideration for implant
prostheses is the available bone in the edentulous span. e place-
ment of endosteal dental implants requires adequate bone volume
at the desired locations for ideal prosthetic support. With insuf-
cient bone volume, several surgical techniques may be used to
reconstruct the decient ridge in preparation for implant place-
ment, including bone spreading (ridge splitting), bone growth
factors, particulate grafting (allograft, xenograft, alloplast), and
autogenous grafting (intraoral or extraoral donor sites).
e number of key factors present and the geometry of a bony
defect are important considerations in the selection of a modal-
ity for ridge augmentation.
1
In general the fewer the number of
remaining bony walls, the greater is the need for osteopromotive
techniques. Although allografts and guided bone regeneration
techniques have been used predictably in slight-to-moderate bone
regeneration (primarily for inadequate width in the horizontal
dimension), these methods have limitations and have been found
to produce less favorable results in the treatment of larger bone
deciencies.
2-13
Ideally the most predictable bone graft mate-
rial possesses osteoconductive, osteoinductive, and osteogenic
properties. e only type of bone-grafting material that maintains
all three of these regenerative properties is autogenous (autolo-
gous) bone. erefore autologous cortical/trabecular bone grafts
may be considered and have been proved to be highly success-
ful for the repair of moderate-to-severe alveolar atrophy and bone
defects (Fig. 38.1).
14-28
History of Autogenous Bone Grafts
e use of iliac crest autologous bone blocks with osteointegrated
implants was initially described by Brånemark etal.
29
and is now
an accepted procedure in oral and maxillofacial rehabilitation.
Although the iliac crest is often used in oral and maxillofacial
reconstruction with dental implants,
30-34
there are many disad-
vantages related to harvesting bone from the ilium. e surgery
is far more aggressive than intraoral techniques and it must be
performed in a hospital setting under general anesthesia. is ulti-
mately will increase patient cost, and complications from the sur-
gery, such as neurosensory and gait disturbances are increased.
35
As an alternative to the iliac crest, there are multiple autogenous
donor graft sites that originate intraorally; these include the man-
dibular symphysis, mandibular ramus, and maxillary tuberosity.
In the literature the mandibular symphysis was one of the rst
intraoral donor sites reported. Early case reports described its use
in the repair of intraoral birth defects, such as cleft palates.
36,37
In
1992 Misch etal.
38
expanded the indications for use of the man-
dibular symphysis and ramus block bone grafts with endosteal
dental implants. In the repair of localized alveolar defects of the
jaws, bone grafts harvested from the intraoral sites known to oer
several advantages.
20,38-41
e main advantage of intraoral versus
extraoral donor grafts is their convenient surgical access and lower
morbidity. e proximity of donor and recipient sites can reduce
operative and anesthesia time, making them ideal for outpatient
implant surgery. In addition, patients report minimal donor site
discomfort compared with bone harvested from the iliac crest or
other extraoral donor sites.
19,20,38-45
Bone harvested from the max-
illofacial region appears to have inherent biological advantages in
bone graft augmentation. is may be attributed to the embryo-
logic origin of the donor bone.
43,46-51
e majority of bones in the
human skeleton are of endochondral origin (from a cartilaginous
precursor). With the exception of alveolar bone and the man-
dibular condyles, the maxilla and body of the mandible develop
intramembranously.
52
It has been demonstrated that membranous

1055
CHAPTER 38 Intraoral Autogenous Bone Grafting
bone grafts show less resorption in comparison with endochon-
dral bone grafts.
46,47,49,53-56
Although cancellous grafts revascular-
ize more rapidly than cortical grafts,
14
cortical membranous grafts
revascularize more rapidly than endochondral bone grafts, with
a thicker cancellous component.
48,57
Early revascularization of
membranous bone grafts results in an improved maintenance of
graft volume.
48,56-58
It is also theorized that bone of ectomesen-
chymal origin, such as the mandible, has a better potential for
incorporation in the maxillofacial region because of a biochemical
similarity in the protocollagen of the donor and recipient bone.
59
More recent research suggests that grafted bone independent from
its embryogenic origin will mimic the properties of the recipient
bone.
60
e inductive capacity of cortical grafts is explained by
their higher concentration of bone morphogenetic proteins.
60-62
Bone from the maxillofacial skeleton contains increased concen-
trations of growth factors, which may lead to a greater capacity for
bone repair and graft retention.
63
Another hypothesis is that the
improved survival of craniofacial bone grafts is simply caused by
their three-dimensional structure.
64,65
Because these grafts have a
thicker cortical volume, they resorb at a slower rate.
53,54,57,66
In
bone graft reconstruction, an emphasis has been placed on the
transplantation of viable osteoprogenitor cells from cancellous
marrow grafts, because the majority of osteoblasts are present in
cancellous bone.
18
However, because of signicant graft resorp-
tion associated with cancellous block grafts from endochondral
donor bone, they are not the primary donor bone in reconstruc-
tion of mandibular discontinuity defects and ridge augmentation
for soft tissue–supported prostheses.
16,18,55-57,67,68
In contrast, cor-
ticocancellous block grafts harvested from the ilium have greater
bone volume compared with particulate cancellous grafts.
57
When
endosteal implants are surgically placed in corticocancellous bone,
it has been observed that bone resorption is slower. is may be
because of the microarchitecture of the bone graft (i.e., cortical
compared with cancellous).
Cortical bone harvested from the mandible exhibits slower
graft resorption and excellent graft incorporation into the host
bone compared with cancellous bone grafts.
57
is is due to the
vast amounts of osteocytes, growth factors, and bone morphoge-
netic protein contained in cortical bone. is facilitates angio-
genesis and osteoblast migration into the graft site.
69-72
It has
also been shown that the dense structure of the cortical grafts
oers improved implant stability and interfacial stress transmis-
sion on implant loading.
73-75
When used in block bone grafting,
the results have been consistent, with excellent graft stabil-
ity.
19-23,25,26,38-45,76-91
Mandibular block bone grafts may be har-
vested from the residual ridge, symphysis, body, and ascending
ramus (Fig. 38.2).
Preoperative Evaluation of Recipient Site
A preoperative, comprehensive evaluation of the host graft site
is extremely important. e implant clinician must identify
any esthetic concerns, the graft dimensions needed to recon-
struct the osseous deciency or zone of atrophy, the soft and
hard tissue topography, and the periodontal and endodontic
health of the adjacent teeth.
38,92,93
e host site should ideally
be evaluated in width, height, and length. In general the most
predictable bone augmentation sites require only the width
dimension and extend for one tooth. is provides mesiodistal
and apical walls of host bone. A one-tooth span provides ease
A
B
Fig. 38.1 Autogenous Bone Grafting: (A) Clinical image depicting block
grafting to a large defect in the maxillary left central and incisor area. (B)
Post-graft healing allows for ideal placement’s of dental implants.
A
B
Fig. 38.2 (A) The symphysis block graft is usually harvested approxi-
mately 5 mm below the roots of the anterior teeth and extends to the
lingual plate. (B) The symphysis and ramus region are two of the most
popular sites that are harvested for intraoral defects.

of soft tissue manipulation and minimal risk for incision line
opening. e least predictable bone graft sites are more than
four teeth in length and require more than 5 mm of height and
width of bone (Fig. 38.3).
e implant clinician must always take into consideration the
nal prosthesis in the treatment planning of osseous defects. When
an FP-1 prosthesis is the treatment of choice, the adjacent teeth
next to the host graft site should ideally have bone on the roots to
a level within 2 mm of the cement-enamel junction. When a bone
graft is placed adjacent to a tooth root (rather than bone), the graft
most often resorbs to the level of the existing bone on the adjacent
tooth root. erefore in a one-intratooth defect, a line drawn from
each bone level on the adjacent roots is the maximum bone height
that can be predictably expected.
In selection of the donor bone for a graft site the graft recipi-
ent site needs to be evaluated in terms of width and height graft
requirements. When greater than 4 mm of donor bone graft width
is required (C−w bone volume), the mandibular symphysis is the
preferable donor site because of the corticocancellous nature of
the graft. When donor graft requirements are less than 4 mm in
width, the ascending ramus of the mandible should be considered
(Division B to B−w bone volume). When considering atrophy in
the vertical dimension, the symphysis of the mandible is a good
source of bone because of the greater volume of bone that can be
acquired.
An accurate radiographic assessment is imperative for com-
plete assessment of the osseous defect. Ideally preoperative
imaging studies should include a cone beam computed tomo-
graphic (CBCT) scan because they have become the standard
of care in preoperative implant surgical planning and in the
evaluation of the recipient and donor sites.
94-96
Mounted study
casts on a semiadjustable articulator of the patient’s jaws allow
the implant team to fully evaluate the anatomy of the jaws
and teeth that cannot be fully appreciated while examining the
oral cavity. In addition to mounted study models, a diagnos-
tic wax-up of the reconstructed jaw and dentition will help to
determine graft dimensions such as width, height, and implant
positioning in relation to the opposing dentition. From this
information, surgical templates may be fabricated with respect
to the ideal implant position in relation to the position of the
nal prosthesis (Fig. 38.4).
38,41,94,95
Preparation of Recipient Site
e recipient graft site should be clinically evaluated before
bone harvesting is initiated. is assessment allows the clinician
to obtain accurate graft dimensions that are required to recon-
struct osseous defects or zones of atrophy in preparation for future
implant placement. Soft tissue incisions to expose the recipient
site are made within attached keratinized tissue. In an edentulous
ridge the soft tissue incision is made slightly lingual to the gingival
crest to reduce the risk for incision lines opening from jaw move-
ment and postsurgical edema. When harvesting a monocortical
block of bone, vertical releasing incisions are made anterior and
posterior to the crestal incision line to provide good visualization
of the surgical site and ease of graft harvest, and to avoid tearing
of the soft tissue ap. e soft tissue reection of the ap distal to
the graft site may be a full- or split-thickness reection to facilitate
soft tissue healing and reduce incision line opening (Figs. 38.5
and 38.6).
Selection of Intraoral Donor Site
After the recipient site has been reviewed, the selection of the
donor site can be determined. e severity of the defect basically
determines if this graft can be taken from the ramus or in major
defects, from the mandibular symphysis. In minor defects where
cancellous bone is applicable, bone form the maxillary tuberosity
can be considered. It is always preferable to use autogenous bone
as the graft material in this type of case.
Mandibular Symphysis Donor Site
Anatomy
e mandibular symphysis describes the area in the midline of
the mandible where the two lateral halves of the mandible fuse
at an early period of life. e median ridge divides and encloses
the triangular eminence or mental protuberance. e base of the
protuberance is depressed in the center and is raised on either side
to form the mental tubercle. e most inferior aspect of the man-
dibular symphysis is termed the “menton,” and this area serves as
the origin of the geniohyoid and genioglossus muscles (Fig. 38.7).
Because the average interforaminal distance is greater than 4 cm,
the symphysis is ideal for recipient sites that require large intra-
oral grafts. In general the symphysis has proven to be a good graft
choice for graft reconstruction cases that require graft sizes of four
or more teeth, especially when both vertical and horizontal de-
ciencies are present.
A
B
Fig. 38.3 Clinical evaluation of the underlying bone is often misleading.
(A) Clinical evaluation of edentulous site. (B) After mucoperiosteal flap, tis-
sue is reflected to reveal significant bony defect.
1056
PART VII Soft and Hard Tissue Rehabilitation

A
BC
Fig. 38.4 Cone Beam Computed Tomographic Evaluation of Edentulous Space. (A) Three-dimen-
sional image of edentulous site showing compromised width. (B) Cross section of compromised bone. (C)
Cross section showing accurate height and width measurements.
AB
Fig. 38.5 Papilla-Sparing Incision. (A) Broad-based incision maintaining the papilla. (B) Full reflection
revealing the bony defect that will dictate the donor site graft.

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PART VII Soft and Hard Tissue Rehabilitation
Radiographic Evaluation
As part of the treatment planning process, CBCT imaging stud-
ies are recommended to evaluate the symphysis to determine the
anatomic bone morphology, which includes the approximate
length of the mandibular teeth, the distance between the mental
foramina, and the vertical height of bone between the root apices
and the inferior border of the mandible. CBCT imaging allows
comprehensive three-dimensional visualization of the graft site,
avoidance of unwanted complications, especially violation of the
oor of the mouth with its highly vascular structures (e.g., sub-
lingual and submental arteries). CBCT imaging is superior to
plain lm radiographs (e.g., panoramic) because it can provide
the clinician with anatomic information in three dimensions
that are not available on two-dimensional lms. However, intra-
operative periapical radiographs may be used to ascertain the
apical location of the incisor teeth to prevent injury to the roots
of the anterior teeth.
It is imperative to determine the buccal-lingual dimension of
available bone throughout the symphysis area. Great care should
be exercised to avoid hourglass mandibles because perforation of
the lingual plate may lead to fracture or damage to blood vessels.
e width of the mandible in the midline is usually the greatest
dimension and decreases toward the mental foramen area. Man-
dibular symphysis width is several millimeters narrower in the
region of the premolar and canines, compared with the midline
(Fig. 38.8).
e average dimension of the anterior mandible between
the mental foramina is approximately 44 mm, with African
American males having the greatest distance, followed by white
males, and African American females.
97
It is recommended that
all osteotomy cuts remain a minimum of 5 mm from the ante-
rior aspect of the mental foramen to avoid injury to the mental
neurovascular bundle and mental nerve. In a study by Monta-
zem etal.,
98
dentate cadaver mandibular blocks were harvested
from the mandibular symphysis to evaluate the maximum bone
quantity without causing damage to the mental nerve. When
two symmetric blocks were measured from each site, the average
was 21 × 10 × 7 mm, the largest was 25 × 13 × 9 mm, and the
smallest measured 21 × 6.5 × 6 mm.
98
erefore the mandibular
symphysis is an ideal donor site for harvesting cortico-cancellous
blocks (Fig. 38.9).
Anesthesia
e anterior symphyseal region of the mandible is innervated by
the mandibular branch of the fth cranial nerve (V3) and cervi-
cal nerves from C-3 and C-4. Bilateral dental or Akinosi (closed-
mouth) blocks with lidocaine 2% (1:100,000 epinephrine) and
Marcaine 0.5% (1:200,000 epinephrine) can be used to obtain V3
innervation anesthesia. Inltration anesthesia is then performed
anterior and inferior to the mental foramen and in the midline at
the base of the mental protuberance.
Incision and Reflection
Surgical access to the symphysis is accomplished using crestal
or vestibular incisions. When incisor teeth are present, a ves-
tibular approach is recommended as reection of the soft tissue
around the anterior teeth may result in tissue recession and
root exposure soft tissue healing.
99
In addition, a vestibular
incision is less traumatic and results in reduced postopera-
tive discomfort. However, the vestibular incision will usually
result in more intraoperative bleeding and the highest risk for
incision line opening, but the least risk for soft tissue changes
around the teeth and root exposure after healing. It also creates
much simpler access to the symphysis area and allows for easier
suturing of the incision line. Limiting the distal extent of the
vestibular incision to the canine tooth area (i.e., mesial of the
canine) will reduce the incidence of mental nerve neurosensory
impairment.
38,39,44
When there is a high mucogingival junc-
tion (MGJ) or high muscle attachments, a sulcular incision
may be indicated because a vestibular incision would have a
higher incidence of incision line opening. In addition, sulcular
incisions are advantageous when less than 4 mm of keratin-
ized gingival height is found around the lower anterior teeth
because incision line opening is a greater risk. is is often seen
when the mentalis muscle is large and parafunctional forces in
this region exist. e sulcular incision carries the least risk for
incision line opening after healing but has an increased risk for
root exposure. e sulcular approach is also the most time con-
suming approach from the standpoint of suturing (Fig. 38.10).
Using a scalpel or electrocautery, an incision is made through
the mucosa and periosteum down to the symphysis bone between
the bilateral canine teeth. Using a periosteal elevator, the soft tis-
sue ap is reected (full-thickness) o of the anterior mandible.
Full-thickness reection is required so that no soft tissue remains
on the donor bone that could interfere with healing (Figs. 38.11
and38.12).
To avoid ptosis of the chin, it is recommended that soft tis-
sue dissection to the inferior border of the mandible be avoided.
is limited reection prevents complete reection of the mentalis
muscle from its lower attachment to the bone.
Fig. 38.6 Larger trapezoid flap exposing large undercuts on facial and
lingual.
Mental
protuberance
Mental
tubercle
Fig. 38.7 Mandibular symphysis anatomy showing the mental protuber-
ance and the mental tubercle.

1059
CHAPTER 38 Intraoral Autogenous Bone Grafting
A
B
C
Fig. 38.8 Cone Beam Computed Tomography Evaluation. (A) It is very important not to solely treat-
ment plan the anterior mandible via the two-dimensional or three-dimensional panoramic image. (B) Three-
dimensional image depicting hourglass anatomy. (C) Cross section showing severe undercuts.
Fig. 38.9 The average interforaminal distance between the mental foramen is greater than 44 mm, and
accurate measurements should be determined before graft harvesting.

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PART VII Soft and Hard Tissue Rehabilitation
Donor Site Osteotomy Harvest
After the symphysis is exposed, the osteotomy for the graft har-
vest is planned. e dimensions of the block bone graft are deter-
mined by the size of the host bone defect. e osteotomies may
be performed with a surgical ssure bur (557, 702—straight 1:1
handpiece), oscillating saw, or Piezotome unit. In general the
Piezosurgery unit allows more ecient and bone-saving osteot-
omy cuts (Fig. 38.13).
Piezotome surgery (Acteon Corp.) is a technology that uses a
modulated ultrasonic frequency to cut or sever mineralized tis-
sue. is ultrasonic surgery technique uses microoscillations (i.e.,
60–200 m/sec at 25–29 kHz) to cut hard tissue, without damag-
ing soft tissue. With this type of surgical modality, precision cuts
can be prepared and greater bone graft quantities can be harvested
on a predictable basis. In addition, visibility is improved because
a cavitation eect is created from the irrigation/cooling solution
that is used. Numerous studies have shown the ultrasonic bone
cutting technique to be more favorable than conventional rotary
instruments.
100
A
B
C
Fig. 38.10 (A) Sulcular incisions are usually made in the anterior mandible
for a symphysis harvest when the keratinized tissue is less than 4 mm in
height or when a heavier musculature is observed. (B) The incision extends
distal to the canines, and a vertical release incision is made anterior and
above the height of the mental foramen. A full-thickness mucoperiosteal
flap reflection exposes the symphysis for the harvest. (C) A sulcular inci-
sion has less risk for postoperative incision line opening; however, there is
a greater risk for root exposure after healing.
A
B
C
Fig. 38.11 (A) A vestibular incision is made 5 to 10 mm below the muco-
gingival junction when 4 to 9 mm of keratinized tissue height is observed
on the facial of the mandibular anterior teeth. (B) The incision extends to
the distal of the canines, and a vertical release incision is made for approxi-
mately 10 mm (above the height of the mental foramen). A full-thickness
mucoperiosteal reflection exposes the mandibular symphysis. (C) Vestibu-
lar incisions often heal with scar formation.

1061
CHAPTER 38 Intraoral Autogenous Bone Grafting
e harvesting of the symphysis block includes four dierent
osteotomy cuts: (1) superior, (2) inferior, (3) right vertical, and (4)
left vertical (Figs. 38.14 and 38.15).
Superior Cut. e superior bone cut is usually made rst and
is dictated by the location of the mandibular incisor and canine
teeth. To avoid root injury of the incisor teeth, when harvesting
blocks of bone from the symphysis, it is recommended to remain
a minimum of 5 mm apical to the apices of the incisor and canine
teeth. Usually the canine teeth are much longer than the incisor
teeth (i.e., incisors: 12–14 mm, canines: 16 mm).
101
e angu-
lation of the superior cut is slightly converging (i.e., with respect
to the lingual plate) because this will minimize injury to the tooth
roots and allow for easier removal of the bone. e depth of the
osteotomy should always be through the labial cortex; however,
it should never be extended lingually to the lingual cortical plate
(Fig. 38.16).
Inferior Cut. e inferior bone cut is often the most dicult
to perform because access is always dicult and challenging. Care
should be exercised not to compromise the inferior border of the
mandible because this may cause iatrogenic fracture of the sym-
physis area and possibly create a discontinuity defect. e horizon-
tal inferior osteotomy should be at least 5 mm or more superior to
the inferior border of the mandible, and the lingual cortical plate
should be preserved so that the lingual plate does not fracture o
during the harvest.
Vertical Cuts. Bilateral vertical cuts are made to connect the hori-
zontal superior and inferior cuts. e location of these cuts must be
at a minimum 5 mm anterior to each mental foramen. e presence
of an anterior loop should always be evaluated and when present,
proper modication to the location of the cuts should be adjusted. As
the horizontal and vertical cuts are connected, care should be taken
to make sure all four cuts are completely through the cortical plates
and that they each connect with the adjacent cut. Small islands of
intact bone can prevent the block from freely being removed from
the donor site. (Fig. 38.17).
Block Removal
Block removal from the symphysis is usually completed with a
straight/curved bone chisel and mallet or a Potts elevator. e
chisel/elevator is usually placed in one of the vertical cut areas,
and an elevated force is applied to verify movement of the block.
If no movement of the block is present, the osteotomies may be
deepened slightly and reverication that all cuts are continuous.
e chisel can be used with the mallet; however, the mandible
should be stabilized to prevent any damage to the temporoman-
dibular joint. Ideally the patient should maintain his or her teeth
in maximum intercuspation.
After block removal, cancellous bone may be available (i.e.,
determined by CBCT cross-sections) to harvest to supplement
Fig. 38.12 When there exists an abundant amount of attached keratin-
ized tissue on the facial aspect of the mandibular anterior teeth, an incision
in the keratinized tissue is of benefit. The incision is made to the distal of
the canines. In this case a midline vertical incision was made, because the
symphysis harvest was limited in size.
Piezotome
Bur
Bur
Bur
AB
CDE
Piezotome
Piezotome
Fig. 38.13 Piezotome (Acteon) versus Bur. (A) Piezotome surgical unit. (B) Surgical image showing the
superior osteotomy cut with the Piezotome. (C) Cadaver study showing a more ideal osteotomy with a Piezo-
tome surgery unit in comparison with a bur. (D and E) Harvested block comparing the Piezotome and bur.

1062
PART VII Soft and Hard Tissue Rehabilitation
any voids in the block graft. Bone curettes of varying sizes will
allow for the available cancellous bone to be removed from the
donor site.
102
Care must be exercised not to perforate the lingual
cortical plate. In some cases, because of the size of the block or the
acute angle of the symphysis, the block outline may require sec-
tioning into two sections. is will allow for easier block removal
because two blocks of bone can be harvested from the symphysis
instead of one large block of bone. Another option is to maintain
a section of bone in the midline of the symphysis because this
will decrease the risk for altering the postoperative appearance of
the chin, especially when the patient has a prominent chin point.
After the bone block is harvested, the defect can be lled with a
particulate graft material (e.g., microporous hydroxyapatite and
a collagen membrane) to minimize the possibility of a defect and
to help to restore the contour of the mandible (Fig. 38.18; Boxes
38.1 and 38.2).
Closure
If a vestibular incision is used, a two-layered soft tissue closure is
recommended for suturing. e periosteum is rst closed with
resorbable suture (e.g., 4–0 or 5–0 Vicryl), as well as the men-
talis muscle and vestibular mucosa. is is followed by the outer
tissue closure with a high tensile strength suture material (e.g.,
Vicryl, PTFE). To allow for ease of closure, the patient should
bite into the centric occlusion, which also decreases tension on
the ap. Postoperative pressure dressings in the form of pressure
5 mm
5 mm
5 mm
10 mm
BA
Fig. 38.14 (A) The guidelines for the symphysis block harvest are usually 5 mm from each mental fora-
men, 5 mm below the roots of the anterior teeth, and 5 mm from the inferior border of the mandible. (B)
The superior osteotomy for the bone block is made 5 mm from the apex of the mandibular anterior teeth.
The block margin slopes down in the canine region because of the longer roots.
AB
C
Fig. 38.15 (A) Cone beam computed tomography cross section in midline showing buccal and lin-
gual contours. (B) Osteotomy cuts should not be perpendicular to the outer buccal plate because block
removal will be difficult. (C) Osteotomy cuts should converge toward the lingual to allow for easier removal.

1063
CHAPTER 38 Intraoral Autogenous Bone Grafting
A
B
Fig. 38.17 Symphysis Graft Outline. (A) Outline too close to mental
foramen and apical regions of the teeth. (B) Ideal outline with ideal space
from the mental foramen and teeth roots.
A
B
Fig. 38.16 (A) When in doubt on the location of the superior cut, a radiopaque material may be placed in
the osteotomy and evaluated radiographically. (B) The radiograph reveals the initial osteotomy is too close
to the canine root and should be 6 mm more apical in this region.
Fig. 38.18 In some cases, involving large blocks, the bone should be
sectioned in half to allow for easier removal.
Indications
• Horizontalandverticalridgeaugmentation
• Thickergraftrequired(corticocancellous)
• Maximum:0.7×1.5×6cm
Advantages
• Easyaccess
• Canobtainlargeamountofcancellousbone
• Usuallyacorticocancellousgraft
Disadvantages
• Alteredsensationofmandibularanteriorteeth
• Inferioralveolarnervedamage
• Patientcosmeticconcerns
• Morechallengingclosure
• Greaterpossibilityofincisiondehiscence
BOX
38.1
Symphysis Bone Graft

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105438Intraoral Autogenous Bone GraftingC. STEPHEN CALDWELL AND CARL E. MISCHTreatment plans in implant dentistry in the past used existing bone volume to determine the location and type of implant and restorations were adapted to accommodate irregulari-ties related to implant locations. In abundant bone (Division A), endosseous root form implants were inserted; in bone of moderate width (Division B), blade implants were placed; and in inadequate height of bone (Division C−h), subperiosteal implants were the treatment of choice.Treatment planning has dramatically changed. e nal pros-thesis type and design is rst determined, followed by determin-ing the ideal implant positions, numbers, and sizes. e available bone is often inadequate to provide the foundation required for a predictable treatment plan. As a consequence, bone grafting has become a more frequent solution for achieving long-term success.In addition to the biomechanical and functional needs signi-cant esthetic considerations need to be included in planning a case. Bone grafting is often indicated to allow placement of an implant in the proper location for an ideal esthetic result. In addition, the soft tissue drape often requires enhancement in the esthetic zone as the bone foundation sets the tone for the soft tissue drape. erefore when ideal crown contours (FP-1) and soft tissue are desired, bone augmentation is an important aspect of the treat-ment plan. As a result of biomechanical-based foundations and esthetic desires, a primary diagnostic consideration for implant prostheses is the available bone in the edentulous span. e place-ment of endosteal dental implants requires adequate bone volume at the desired locations for ideal prosthetic support. With insuf-cient bone volume, several surgical techniques may be used to reconstruct the decient ridge in preparation for implant place-ment, including bone spreading (ridge splitting), bone growth factors, particulate grafting (allograft, xenograft, alloplast), and autogenous grafting (intraoral or extraoral donor sites).e number of key factors present and the geometry of a bony defect are important considerations in the selection of a modal-ity for ridge augmentation.1 In general the fewer the number of remaining bony walls, the greater is the need for osteopromotive techniques. Although allografts and guided bone regeneration techniques have been used predictably in slight-to-moderate bone regeneration (primarily for inadequate width in the horizontal dimension), these methods have limitations and have been found to produce less favorable results in the treatment of larger bone deciencies.2-13 Ideally the most predictable bone graft mate-rial possesses osteoconductive, osteoinductive, and osteogenic properties. e only type of bone-grafting material that maintains all three of these regenerative properties is autogenous (autolo-gous) bone. erefore autologous cortical/trabecular bone grafts may be considered and have been proved to be highly success-ful for the repair of moderate-to-severe alveolar atrophy and bone defects (Fig. 38.1).14-28History of Autogenous Bone Graftse use of iliac crest autologous bone blocks with osteointegrated implants was initially described by Brånemark etal.29 and is now an accepted procedure in oral and maxillofacial rehabilitation. Although the iliac crest is often used in oral and maxillofacial reconstruction with dental implants,30-34 there are many disad-vantages related to harvesting bone from the ilium. e surgery is far more aggressive than intraoral techniques and it must be performed in a hospital setting under general anesthesia. is ulti-mately will increase patient cost, and complications from the sur-gery, such as neurosensory and gait disturbances are increased.35 As an alternative to the iliac crest, there are multiple autogenous donor graft sites that originate intraorally; these include the man-dibular symphysis, mandibular ramus, and maxillary tuberosity.In the literature the mandibular symphysis was one of the rst intraoral donor sites reported. Early case reports described its use in the repair of intraoral birth defects, such as cleft palates.36,37 In 1992 Misch etal.38 expanded the indications for use of the man-dibular symphysis and ramus block bone grafts with endosteal dental implants. In the repair of localized alveolar defects of the jaws, bone grafts harvested from the intraoral sites known to oer several advantages.20,38-41 e main advantage of intraoral versus extraoral donor grafts is their convenient surgical access and lower morbidity. e proximity of donor and recipient sites can reduce operative and anesthesia time, making them ideal for outpatient implant surgery. In addition, patients report minimal donor site discomfort compared with bone harvested from the iliac crest or other extraoral donor sites.19,20,38-45 Bone harvested from the max-illofacial region appears to have inherent biological advantages in bone graft augmentation. is may be attributed to the embryo-logic origin of the donor bone.43,46-51 e majority of bones in the human skeleton are of endochondral origin (from a cartilaginous precursor). With the exception of alveolar bone and the man-dibular condyles, the maxilla and body of the mandible develop intramembranously.52 It has been demonstrated that membranous 1055CHAPTER 38 Intraoral Autogenous Bone Graftingbone grafts show less resorption in comparison with endochon-dral bone grafts.46,47,49,53-56 Although cancellous grafts revascular-ize more rapidly than cortical grafts,14 cortical membranous grafts revascularize more rapidly than endochondral bone grafts, with a thicker cancellous component.48,57 Early revascularization of membranous bone grafts results in an improved maintenance of graft volume.48,56-58 It is also theorized that bone of ectomesen-chymal origin, such as the mandible, has a better potential for incorporation in the maxillofacial region because of a biochemical similarity in the protocollagen of the donor and recipient bone.59 More recent research suggests that grafted bone independent from its embryogenic origin will mimic the properties of the recipient bone.60 e inductive capacity of cortical grafts is explained by their higher concentration of bone morphogenetic proteins.60-62 Bone from the maxillofacial skeleton contains increased concen-trations of growth factors, which may lead to a greater capacity for bone repair and graft retention.63 Another hypothesis is that the improved survival of craniofacial bone grafts is simply caused by their three-dimensional structure.64,65 Because these grafts have a thicker cortical volume, they resorb at a slower rate.53,54,57,66 In bone graft reconstruction, an emphasis has been placed on the transplantation of viable osteoprogenitor cells from cancellous marrow grafts, because the majority of osteoblasts are present in cancellous bone.18 However, because of signicant graft resorp-tion associated with cancellous block grafts from endochondral donor bone, they are not the primary donor bone in reconstruc-tion of mandibular discontinuity defects and ridge augmentation for soft tissue–supported prostheses.16,18,55-57,67,68 In contrast, cor-ticocancellous block grafts harvested from the ilium have greater bone volume compared with particulate cancellous grafts.57 When endosteal implants are surgically placed in corticocancellous bone, it has been observed that bone resorption is slower. is may be because of the microarchitecture of the bone graft (i.e., cortical compared with cancellous).Cortical bone harvested from the mandible exhibits slower graft resorption and excellent graft incorporation into the host bone compared with cancellous bone grafts.57 is is due to the vast amounts of osteocytes, growth factors, and bone morphoge-netic protein contained in cortical bone. is facilitates angio-genesis and osteoblast migration into the graft site.69-72 It has also been shown that the dense structure of the cortical grafts oers improved implant stability and interfacial stress transmis-sion on implant loading.73-75 When used in block bone grafting, the results have been consistent, with excellent graft stabil-ity.19-23,25,26,38-45,76-91 Mandibular block bone grafts may be har-vested from the residual ridge, symphysis, body, and ascending ramus (Fig. 38.2). Preoperative Evaluation of Recipient SiteA preoperative, comprehensive evaluation of the host graft site is extremely important. e implant clinician must identify any esthetic concerns, the graft dimensions needed to recon-struct the osseous deciency or zone of atrophy, the soft and hard tissue topography, and the periodontal and endodontic health of the adjacent teeth.38,92,93 e host site should ideally be evaluated in width, height, and length. In general the most predictable bone augmentation sites require only the width dimension and extend for one tooth. is provides mesiodistal and apical walls of host bone. A one-tooth span provides ease AB• Fig. 38.1 Autogenous Bone Grafting: (A) Clinical image depicting block grafting to a large defect in the maxillary left central and incisor area. (B) Post-graft healing allows for ideal placement’s of dental implants.AB• Fig. 38.2 (A) The symphysis block graft is usually harvested approxi-mately 5 mm below the roots of the anterior teeth and extends to the lingual plate. (B) The symphysis and ramus region are two of the most popular sites that are harvested for intraoral defects. of soft tissue manipulation and minimal risk for incision line opening. e least predictable bone graft sites are more than four teeth in length and require more than 5 mm of height and width of bone (Fig. 38.3).e implant clinician must always take into consideration the nal prosthesis in the treatment planning of osseous defects. When an FP-1 prosthesis is the treatment of choice, the adjacent teeth next to the host graft site should ideally have bone on the roots to a level within 2 mm of the cement-enamel junction. When a bone graft is placed adjacent to a tooth root (rather than bone), the graft most often resorbs to the level of the existing bone on the adjacent tooth root. erefore in a one-intratooth defect, a line drawn from each bone level on the adjacent roots is the maximum bone height that can be predictably expected.In selection of the donor bone for a graft site the graft recipi-ent site needs to be evaluated in terms of width and height graft requirements. When greater than 4 mm of donor bone graft width is required (C−w bone volume), the mandibular symphysis is the preferable donor site because of the corticocancellous nature of the graft. When donor graft requirements are less than 4 mm in width, the ascending ramus of the mandible should be considered (Division B to B−w bone volume). When considering atrophy in the vertical dimension, the symphysis of the mandible is a good source of bone because of the greater volume of bone that can be acquired.An accurate radiographic assessment is imperative for com-plete assessment of the osseous defect. Ideally preoperative imaging studies should include a cone beam computed tomo-graphic (CBCT) scan because they have become the standard of care in preoperative implant surgical planning and in the evaluation of the recipient and donor sites.94-96 Mounted study casts on a semiadjustable articulator of the patient’s jaws allow the implant team to fully evaluate the anatomy of the jaws and teeth that cannot be fully appreciated while examining the oral cavity. In addition to mounted study models, a diagnos-tic wax-up of the reconstructed jaw and dentition will help to determine graft dimensions such as width, height, and implant positioning in relation to the opposing dentition. From this information, surgical templates may be fabricated with respect to the ideal implant position in relation to the position of the nal prosthesis (Fig. 38.4).38,41,94,95Preparation of Recipient Sitee recipient graft site should be clinically evaluated before bone harvesting is initiated. is assessment allows the clinician to obtain accurate graft dimensions that are required to recon-struct osseous defects or zones of atrophy in preparation for future implant placement. Soft tissue incisions to expose the recipient site are made within attached keratinized tissue. In an edentulous ridge the soft tissue incision is made slightly lingual to the gingival crest to reduce the risk for incision lines opening from jaw move-ment and postsurgical edema. When harvesting a monocortical block of bone, vertical releasing incisions are made anterior and posterior to the crestal incision line to provide good visualization of the surgical site and ease of graft harvest, and to avoid tearing of the soft tissue ap. e soft tissue reection of the ap distal to the graft site may be a full- or split-thickness reection to facilitate soft tissue healing and reduce incision line opening (Figs. 38.5 and 38.6). Selection of Intraoral Donor SiteAfter the recipient site has been reviewed, the selection of the donor site can be determined. e severity of the defect basically determines if this graft can be taken from the ramus or in major defects, from the mandibular symphysis. In minor defects where cancellous bone is applicable, bone form the maxillary tuberosity can be considered. It is always preferable to use autogenous bone as the graft material in this type of case.Mandibular Symphysis Donor SiteAnatomye mandibular symphysis describes the area in the midline of the mandible where the two lateral halves of the mandible fuse at an early period of life. e median ridge divides and encloses the triangular eminence or mental protuberance. e base of the protuberance is depressed in the center and is raised on either side to form the mental tubercle. e most inferior aspect of the man-dibular symphysis is termed the “menton,” and this area serves as the origin of the geniohyoid and genioglossus muscles (Fig. 38.7). Because the average interforaminal distance is greater than 4 cm, the symphysis is ideal for recipient sites that require large intra-oral grafts. In general the symphysis has proven to be a good graft choice for graft reconstruction cases that require graft sizes of four or more teeth, especially when both vertical and horizontal de-ciencies are present. AB• Fig. 38.3 Clinical evaluation of the underlying bone is often misleading. (A) Clinical evaluation of edentulous site. (B) After mucoperiosteal flap, tis-sue is reflected to reveal significant bony defect.1056PART VII Soft and Hard Tissue Rehabilitation ABC• Fig. 38.4 Cone Beam Computed Tomographic Evaluation of Edentulous Space. (A) Three-dimen-sional image of edentulous site showing compromised width. (B) Cross section of compromised bone. (C) Cross section showing accurate height and width measurements.AB• Fig. 38.5 Papilla-Sparing Incision. (A) Broad-based incision maintaining the papilla. (B) Full reflection revealing the bony defect that will dictate the donor site graft. 1058PART VII Soft and Hard Tissue RehabilitationRadiographic EvaluationAs part of the treatment planning process, CBCT imaging stud-ies are recommended to evaluate the symphysis to determine the anatomic bone morphology, which includes the approximate length of the mandibular teeth, the distance between the mental foramina, and the vertical height of bone between the root apices and the inferior border of the mandible. CBCT imaging allows comprehensive three-dimensional visualization of the graft site, avoidance of unwanted complications, especially violation of the oor of the mouth with its highly vascular structures (e.g., sub-lingual and submental arteries). CBCT imaging is superior to plain lm radiographs (e.g., panoramic) because it can provide the clinician with anatomic information in three dimensions that are not available on two-dimensional lms. However, intra-operative periapical radiographs may be used to ascertain the apical location of the incisor teeth to prevent injury to the roots of the anterior teeth.It is imperative to determine the buccal-lingual dimension of available bone throughout the symphysis area. Great care should be exercised to avoid hourglass mandibles because perforation of the lingual plate may lead to fracture or damage to blood vessels. e width of the mandible in the midline is usually the greatest dimension and decreases toward the mental foramen area. Man-dibular symphysis width is several millimeters narrower in the region of the premolar and canines, compared with the midline (Fig. 38.8).e average dimension of the anterior mandible between the mental foramina is approximately 44 mm, with African American males having the greatest distance, followed by white males, and African American females.97 It is recommended that all osteotomy cuts remain a minimum of 5 mm from the ante-rior aspect of the mental foramen to avoid injury to the mental neurovascular bundle and mental nerve. In a study by Monta-zem etal.,98 dentate cadaver mandibular blocks were harvested from the mandibular symphysis to evaluate the maximum bone quantity without causing damage to the mental nerve. When two symmetric blocks were measured from each site, the average was 21 × 10 × 7 mm, the largest was 25 × 13 × 9 mm, and the smallest measured 21 × 6.5 × 6 mm.98 erefore the mandibular symphysis is an ideal donor site for harvesting cortico-cancellous blocks (Fig. 38.9). Anesthesiae anterior symphyseal region of the mandible is innervated by the mandibular branch of the fth cranial nerve (V3) and cervi-cal nerves from C-3 and C-4. Bilateral dental or Akinosi (closed-mouth) blocks with lidocaine 2% (1:100,000 epinephrine) and Marcaine 0.5% (1:200,000 epinephrine) can be used to obtain V3 innervation anesthesia. Inltration anesthesia is then performed anterior and inferior to the mental foramen and in the midline at the base of the mental protuberance. Incision and ReflectionSurgical access to the symphysis is accomplished using crestal or vestibular incisions. When incisor teeth are present, a ves-tibular approach is recommended as reection of the soft tissue around the anterior teeth may result in tissue recession and root exposure soft tissue healing.99 In addition, a vestibular incision is less traumatic and results in reduced postopera-tive discomfort. However, the vestibular incision will usually result in more intraoperative bleeding and the highest risk for incision line opening, but the least risk for soft tissue changes around the teeth and root exposure after healing. It also creates much simpler access to the symphysis area and allows for easier suturing of the incision line. Limiting the distal extent of the vestibular incision to the canine tooth area (i.e., mesial of the canine) will reduce the incidence of mental nerve neurosensory impairment.38,39,44 When there is a high mucogingival junc-tion (MGJ) or high muscle attachments, a sulcular incision may be indicated because a vestibular incision would have a higher incidence of incision line opening. In addition, sulcular incisions are advantageous when less than 4 mm of keratin-ized gingival height is found around the lower anterior teeth because incision line opening is a greater risk. is is often seen when the mentalis muscle is large and parafunctional forces in this region exist. e sulcular incision carries the least risk for incision line opening after healing but has an increased risk for root exposure. e sulcular approach is also the most time con-suming approach from the standpoint of suturing (Fig. 38.10).Using a scalpel or electrocautery, an incision is made through the mucosa and periosteum down to the symphysis bone between the bilateral canine teeth. Using a periosteal elevator, the soft tis-sue ap is reected (full-thickness) o of the anterior mandible. Full-thickness reection is required so that no soft tissue remains on the donor bone that could interfere with healing (Figs. 38.11 and38.12).To avoid ptosis of the chin, it is recommended that soft tis-sue dissection to the inferior border of the mandible be avoided. is limited reection prevents complete reection of the mentalis muscle from its lower attachment to the bone. • Fig. 38.6 Larger trapezoid flap exposing large undercuts on facial and lingual.Mental protuberanceMental tubercle• Fig. 38.7 Mandibular symphysis anatomy showing the mental protuber-ance and the mental tubercle. 1059CHAPTER 38 Intraoral Autogenous Bone GraftingABC• Fig. 38.8 Cone Beam Computed Tomography Evaluation. (A) It is very important not to solely treat-ment plan the anterior mandible via the two-dimensional or three-dimensional panoramic image. (B) Three-dimensional image depicting hourglass anatomy. (C) Cross section showing severe undercuts.• Fig. 38.9 The average interforaminal distance between the mental foramen is greater than 44 mm, and accurate measurements should be determined before graft harvesting. 1060PART VII Soft and Hard Tissue RehabilitationDonor Site Osteotomy HarvestAfter the symphysis is exposed, the osteotomy for the graft har-vest is planned. e dimensions of the block bone graft are deter-mined by the size of the host bone defect. e osteotomies may be performed with a surgical ssure bur (557, 702—straight 1:1 handpiece), oscillating saw, or Piezotome unit. In general the Piezosurgery unit allows more ecient and bone-saving osteot-omy cuts (Fig. 38.13).Piezotome surgery (Acteon Corp.) is a technology that uses a modulated ultrasonic frequency to cut or sever mineralized tis-sue. is ultrasonic surgery technique uses microoscillations (i.e., 60–200 m/sec at 25–29 kHz) to cut hard tissue, without damag-ing soft tissue. With this type of surgical modality, precision cuts can be prepared and greater bone graft quantities can be harvested on a predictable basis. In addition, visibility is improved because a cavitation eect is created from the irrigation/cooling solution that is used. Numerous studies have shown the ultrasonic bone cutting technique to be more favorable than conventional rotary instruments.100ABC• Fig. 38.10 (A) Sulcular incisions are usually made in the anterior mandible for a symphysis harvest when the keratinized tissue is less than 4 mm in height or when a heavier musculature is observed. (B) The incision extends distal to the canines, and a vertical release incision is made anterior and above the height of the mental foramen. A full-thickness mucoperiosteal flap reflection exposes the symphysis for the harvest. (C) A sulcular inci-sion has less risk for postoperative incision line opening; however, there is a greater risk for root exposure after healing.ABC• Fig. 38.11 (A) A vestibular incision is made 5 to 10 mm below the muco-gingival junction when 4 to 9 mm of keratinized tissue height is observed on the facial of the mandibular anterior teeth. (B) The incision extends to the distal of the canines, and a vertical release incision is made for approxi-mately 10 mm (above the height of the mental foramen). A full-thickness mucoperiosteal reflection exposes the mandibular symphysis. (C) Vestibu-lar incisions often heal with scar formation. 1061CHAPTER 38 Intraoral Autogenous Bone Graftinge harvesting of the symphysis block includes four dierent osteotomy cuts: (1) superior, (2) inferior, (3) right vertical, and (4) left vertical (Figs. 38.14 and 38.15).Superior Cut. e superior bone cut is usually made rst and is dictated by the location of the mandibular incisor and canine teeth. To avoid root injury of the incisor teeth, when harvesting blocks of bone from the symphysis, it is recommended to remain a minimum of 5 mm apical to the apices of the incisor and canine teeth. Usually the canine teeth are much longer than the incisor teeth (i.e., incisors: ∼12–14 mm, canines: ∼16 mm).101 e angu-lation of the superior cut is slightly converging (i.e., with respect to the lingual plate) because this will minimize injury to the tooth roots and allow for easier removal of the bone. e depth of the osteotomy should always be through the labial cortex; however, it should never be extended lingually to the lingual cortical plate (Fig. 38.16). Inferior Cut. e inferior bone cut is often the most dicult to perform because access is always dicult and challenging. Care should be exercised not to compromise the inferior border of the mandible because this may cause iatrogenic fracture of the sym-physis area and possibly create a discontinuity defect. e horizon-tal inferior osteotomy should be at least 5 mm or more superior to the inferior border of the mandible, and the lingual cortical plate should be preserved so that the lingual plate does not fracture o during the harvest. Vertical Cuts. Bilateral vertical cuts are made to connect the hori-zontal superior and inferior cuts. e location of these cuts must be at a minimum 5 mm anterior to each mental foramen. e presence of an anterior loop should always be evaluated and when present, proper modication to the location of the cuts should be adjusted. As the horizontal and vertical cuts are connected, care should be taken to make sure all four cuts are completely through the cortical plates and that they each connect with the adjacent cut. Small islands of intact bone can prevent the block from freely being removed from the donor site. (Fig. 38.17). Block RemovalBlock removal from the symphysis is usually completed with a straight/curved bone chisel and mallet or a Potts elevator. e chisel/elevator is usually placed in one of the vertical cut areas, and an elevated force is applied to verify movement of the block. If no movement of the block is present, the osteotomies may be deepened slightly and reverication that all cuts are continuous. e chisel can be used with the mallet; however, the mandible should be stabilized to prevent any damage to the temporoman-dibular joint. Ideally the patient should maintain his or her teeth in maximum intercuspation.After block removal, cancellous bone may be available (i.e., determined by CBCT cross-sections) to harvest to supplement • Fig. 38.12 When there exists an abundant amount of attached keratin-ized tissue on the facial aspect of the mandibular anterior teeth, an incision in the keratinized tissue is of benefit. The incision is made to the distal of the canines. In this case a midline vertical incision was made, because the symphysis harvest was limited in size.PiezotomeBurBurBurABCDEPiezotomePiezotome• Fig. 38.13 Piezotome (Acteon) versus Bur. (A) Piezotome surgical unit. (B) Surgical image showing the superior osteotomy cut with the Piezotome. (C) Cadaver study showing a more ideal osteotomy with a Piezo-tome surgery unit in comparison with a bur. (D and E) Harvested block comparing the Piezotome and bur. 1062PART VII Soft and Hard Tissue Rehabilitationany voids in the block graft. Bone curettes of varying sizes will allow for the available cancellous bone to be removed from the donor site.102 Care must be exercised not to perforate the lingual cortical plate. In some cases, because of the size of the block or the acute angle of the symphysis, the block outline may require sec-tioning into two sections. is will allow for easier block removal because two blocks of bone can be harvested from the symphysis instead of one large block of bone. Another option is to maintain a section of bone in the midline of the symphysis because this will decrease the risk for altering the postoperative appearance of the chin, especially when the patient has a prominent chin point. After the bone block is harvested, the defect can be lled with a particulate graft material (e.g., microporous hydroxyapatite and a collagen membrane) to minimize the possibility of a defect and to help to restore the contour of the mandible (Fig. 38.18; Boxes 38.1 and 38.2). ClosureIf a vestibular incision is used, a two-layered soft tissue closure is recommended for suturing. e periosteum is rst closed with resorbable suture (e.g., 4–0 or 5–0 Vicryl), as well as the men-talis muscle and vestibular mucosa. is is followed by the outer tissue closure with a high tensile strength suture material (e.g., Vicryl, PTFE). To allow for ease of closure, the patient should bite into the centric occlusion, which also decreases tension on the ap. Postoperative pressure dressings in the form of pressure 5 mm5 mm5 mm10 mmBA• Fig. 38.14 (A) The guidelines for the symphysis block harvest are usually 5 mm from each mental fora-men, 5 mm below the roots of the anterior teeth, and 5 mm from the inferior border of the mandible. (B) The superior osteotomy for the bone block is made 5 mm from the apex of the mandibular anterior teeth. The block margin slopes down in the canine region because of the longer roots.ABC• Fig. 38.15 (A) Cone beam computed tomography cross section in midline showing buccal and lin-gual contours. (B) Osteotomy cuts should not be perpendicular to the outer buccal plate because block removal will be difficult. (C) Osteotomy cuts should converge toward the lingual to allow for easier removal. 1063CHAPTER 38 Intraoral Autogenous Bone GraftingAB• Fig. 38.17 Symphysis Graft Outline. (A) Outline too close to mental foramen and apical regions of the teeth. (B) Ideal outline with ideal space from the mental foramen and teeth roots.AB• Fig. 38.16 (A) When in doubt on the location of the superior cut, a radiopaque material may be placed in the osteotomy and evaluated radiographically. (B) The radiograph reveals the initial osteotomy is too close to the canine root and should be 6 mm more apical in this region.• Fig. 38.18 In some cases, involving large blocks, the bone should be sectioned in half to allow for easier removal.Indications• Horizontalandverticalridgeaugmentation• Thickergraftrequired(corticocancellous)• Maximum:0.7×1.5×6cm Advantages• Easyaccess• Canobtainlargeamountofcancellousbone• Usuallyacorticocancellousgraft Disadvantages• Alteredsensationofmandibularanteriorteeth• Inferioralveolarnervedamage• Patientcosmeticconcerns• Morechallengingclosure• Greaterpossibilityofincisiondehiscence • BOX 38.1 Symphysis Bone Graft 1064PART VII Soft and Hard Tissue Rehabilitationtapes placed over the skin of the chin can reduce the development of hematoma formation, incision line dehiscence, and infection (Figs. 38.19 and 38.20). Alternative Symphysis ProceduresIf a large monocortical bone block is not indicated, circular-shaped bone cores ranging from 4 to 10 mm in diameter may be harvested with a trephine bur for use in alveolar augmentation.103 Trephine burs of varying diameters can remove bone cores of dif-ferent lengths down to the lingual cortex of the mandible. A Molt curette or other instrument is then used to recover the bone core. It is critical that the bone cores be xated and immobilized dur-ing the healing phase to avoid nonunion of the bone core to the native host mandible. After 4 to 6 months of bone healing, dental implants can usually be surgically placed into the grafted bone. After an additional 3-month healing period, the implants may be prosthetically restored. Mandibular Ramus Donor SiteA second intraoral autogenous donor graft site that may be used is the mandibular ramus. e mandibular ramus has many advantages as a potential donor site. is area allows sucient amounts of bone to be harvested for graft reconstruction and provides easy access to the ascending ramus, patient discomfort is less compared with the symphysis graft, and there is reduced risk for neurosensory disturbances from injury to the infe-rior alveolar neurovascular bundle. e primary disadvantage with the use of ramus grafts is that access may be dicult in some cases and the quantity of bone is limited (i.e., mainly in width).Anatomye mandibular ramus is the second largest part of the man-dible (i.e., mandibular body is the largest), and it extends cra-nially from the angle of the mandible and away from the body at approximately 110 degrees. e ramus is quadrilaterally shaped and is made up of two surfaces, four borders, and two processes.Anatomic Surfaces: 1. Lateral surface: It is relatively at and is dened by the internal and external oblique ridges, and the Masseter muscle attach-ment encompasses much of the surface. 2. Medial surface: e medial surface includes the entrance to the mandibular foramen and the inferior alveolar vessels and nerve. e lingula is the surrounding prominent ridge that gives attachment to the sphenomandibular ligament. e mylohyoid groove runs obliquely downward and forward, and is the location for mylohyoid vessels and nerve. e internal pterygoid inserts behind the mylohyoid groove. Anatomic Borders: 1. Inferior border: e lower border is a thicker part of the mandible, which is continuous with the inferior border of the mandible. e lower border junctions with the posterior Incision:vestibular—dependingonaccess,slightlyapicaltomucogingivaljunctionfrommesialofcuspidtomesialofcuspid;analternativeincisionisasulcularincisionSuperior:5mmbelowapicesofanteriorteethInferior:5mmsuperiortotheinferiorborderofmandibleVertical:5mmanteriortomentalforamenBone harvest:chiselandmallet,orPottselevator • BOX 38.2 Symphysis Graft Osteotomy TechniqueABC• Fig. 38.19 Vestibular Closure. (A) Use of a “two layer” closure in a chin graft site limits excess tension on the healing wound as the mentalis mus-cle is flexed. The mentalis can be sutured to its remnants if they are visible or it can be anchored with sutures that pass from the muscle, through the interproximal tissue, around an incisor, and back through the adjacent interproximal papilla to then draw the muscle to its proper level. This is completed on both sides of the symphysis. (B) A second suture line is used to approximate the mucosal layer of the vestibule. Assuring that there is not any tension on the sutured wound. (C) Post operative photo showing a matured vestibular block graft donor site. 1065CHAPTER 38 Intraoral Autogenous Bone GraftingACEBDF• Fig. 38.20 (A) The inferior osteotomy is planned and is usually 5 mm above the inferior border of the mandible when a harvest is primarily for an increased width of bone. (B) A fissure bur may be used to con-nect the dots of the planned bone block. (C) The block is usually designed to be harvested in two pieces. (D) After an osteotome is used to ensure the osteotomy is made up to the lingual plate, the chisel is angled to shear the one block from this landmark. (E) The second bone block is easier to harvest because the bone chisel can slide along the lingual plate with direct access. (F) The bone blocks are positioned in key implant regions, with at least two fixation screws. border at the angle of the mandible (gonial angle). e mas-seter muscle attaches laterally, and the internal pterygoid attaches medially. 2. Anterior border: It is continuous with the oblique line and is thin at the crest. 3. Posterior border: It is thicker and is covered by the parotid gland. 4. Superior border: is is a thin bone that makes up two pro-cesses, the coronoid and condylar. e mandibular notch is a deep concavity that separates the two processes.  1066PART VII Soft and Hard Tissue RehabilitationMMKIGHJLN• Fig. 38.20, cont’d (G) The bone blocks are recontoured in situ to smooth the edges, which might per-forate the soft tissue flaps. (H) Additional particulate bone may be harvested from the symphysis with a rongeur or trephine bur. (I) The particulate bone is placed between the blocks and in any voids between the host bone and blocks. (J) A reentry into the host site after 5 months. (K) The block grafts usually exhibit less resorption compared with the particulate graft (in the center). (L) A drill guide is used to position the implants into the graft site. (M) Four implants are positioned in the grafted site. (N) After 4 months of healing the abutments are inserted and the prosthesis may be fabricated. 1067CHAPTER 38 Intraoral Autogenous Bone GraftingAnatomic Processes: 1. Coronoid process: is is a thin, triangular eminence that allows attachment to the masseter and temporalis muscle. 2. Condylar process: e condylar process ends with the condyle, which is the articular surface for articulation with the articular disk of the temporomandibular joint (Fig. 38.21). Radiographic EvaluationClinical evaluation of the ascending ramus is ideally evaluated via CBCT technology. With the various CBCT views available to evaluate the ramus area, the amount of bone available for grafting, along with the location of the inferior alveolar nerve canal, may be determined. e anteroposterior length of the external oblique and prosthetic “buccal shelf” ranges from no presence from the third to rst molar, to a dominant projection lateral to the body of the mandible. An index nger may be placed on the external oblique ridge of the ascending ramus and lateral aspect of the mandible. Often a ledge is palpable lateral to the second molar region and begins to disappear at the medial of the rst molar. e wider the “ledge” lateral to the molars or body of an edentulous mandible, the wider the ramus block bone that can be harvested. Some mandibles have almost no “buccal shelf,” whereas others are very signicant (i.e., ∼7 mm). Most often the buccal shelf disap-pears at the mid-rst molar region to the anterior and to the third molar region on the posterior aspect. e ramus length is variable, with the most common vertical limit below the coronoid process, because this structure is so very thin that a block section would remove the entire segment. When determining the location of the graft site, there exist three anatomic variables that require clinical and radiographic evaluation. 1. e rst variable includes the buccal-lingual mandibular canal position. Although the buccolingual position of the mandibu-lar canal is variable within the body of the mandible, the dis-tance from the canal to the medial aspect of the buccal cortical plate (medullary bone thickness) has been found to be greatest at the distal half of the rst molar.104 erefore when larger grafts are planned, the anterior vertical bone cut may be made in this area. e vertical bone cuts are progressively deepened until bleeding from the underlying cancellous bone is vis-ible, which will allow for a safe distance from the mandibular canal.105,106 2. e second variable is the distance from the external oblique and ramus to the inferior alveolar canal. e mean anteroposterior width of the ramus is 30.5 mm, with the mandibular foramen located about two-thirds of the distance from the anterior bor-der.105 A CBCT scan is ideally used to assess and evaluate these bony dimensions. e lingula on the medial ramus is the entry point of the inferior alveolar nerve, and its location is variable. It may be at the occlusal plane (most often), above the occlusal plane, or below the occlusal plane. e lingula may be in the anterior third of the ramus, the middle third, or the distal third of the width of the ramus. As a general rule the higher and farther forward the lingula, the closer the inferior alveolar canal is adjacent to the external oblique ridge. As a result the ramus block harvest must be located lateral to the inferior alveolar canal and is usually less than 3 mm thick. e lower and more distal the lingual is in the ramus on the CBCT, the lower the inferior alveolar canal is to the external oblique. As a result the ramus block may be as much as 6 mm in width. 3. e third variable is the width of the posterior ramus. In gen-eral, females have a thinner ramus body and width compared with males. Because of these anatomic variables, a rectangular block of cortical bone 3 to 6 mm in thickness may be har-vested from the ramus.106 e length of the rectangular graft may range from 1 to 3.5 cm, and the height approximately 1 cm.20,44,107 Such anatomic dimensions may correct width de-ciencies involving a span of three to four teeth.Although use of the coronoid process as an autologous graft has been reported,108-110 the amount of bone for ridge augmen-tation is negligible considering the potential postoperative dis-ability of a coronoidectomy.111,112 However, such anatomic size and shape may be used as a veneer graft to gain additional ridge width. e anatomic proximity makes the ramus well suited for augmentation to the posterior mandible inadequate in width (Fig. 38.22).42 Incision and Reflectione surgical procedure to harvest a block bone graft from the ramus is similar to performing a sagittal split ramus oste-otomy.106,113-119 With a scalpel, an incision is initiated on the midcrest of the ridge in the posterior edentulous patient, begin-ning at the base of the retromolar pad. Caution should always be exercised to avoid the retromolar pad in the incision design because this may result in neurosensory impairment issues (i.e., paresthesia, anesthesia, or dysphasia caused by injury of the lin-gual nerve, the chorda tympani nerve, and a sympathetic branch of the parasympathetic nerve to the submandibular gland with the lingual nerve).Initiating the incision on the ascending ramus no higher than the level of the occlusal plane minimizes the possibility of severing the buccal artery or exposing the buccal fat pad.106 e incision continues anteriorly into the buccal sulcus of the molar teeth or posterior ridge area. When making the incision in this area, often a minor bleeding issue may result. At the height of the occlusal plane, the buccal artery crosses the ascending ramus of the man-dible. e maxillary artery traverses anteriorly and laterally to the retromolar pad. If severed, profuse bleeding is observed, which is usually treated with hemostats to clamp the vessel on the lingual aspect of the incision.A mucoperiosteal ap is reected from the mandibular body, exposing the lateral aspect of the ramus. e attachment of the buccinator muscle is observed rst. A periosteal elevator is placed medial to this structure and directly on the bone of the external oblique and along the ramus. e ap is elevated MandibleBone graftsites• Fig. 38.21 The ramus and posterior body may be used as a bone block harvest site. AB C• Fig. 38.22 Ramus Bone Graft. (A) Outline of four major osteotomy cuts. (B) Translucent outline of donor site and its relationship to the inferior alveolar canal. (C) Cross-sectional view of graft site.superiorly along the external oblique ridge. After the facial ap is reected the incision in the midramus may be extended to the attachment of the temporalis muscle. e periosteal ele-vator slides along the ramus 15 mm deep, down the ramus toward the rst premolar region, and identies the mental fora-men. e host site is reected and prepared for receiving the block graft (Fig. 38.23). Donor Site Osteotomy HarvestSuperior Cut. e width of the ramus and the external oblique lateral of the mandibular body are identied. A straight handpiece and a small, round drill (No. 2–4) or a thin at insert on a Piezo-surgery unit punctures the bone 3 to 6 mm (i.e., dependent on the bony thickness as per the CBCT survey) from the lateral aspect of the ramus and external oblique for the superior cut. e holes should allow at least 3 mm of bone on the lingual of the ramus and 2 mm of bone adjacent to the molar teeth (when present). e length of the graft is determined, as dictated by the host site (previously reected and prepared). e penetrating holes, just through the cortical bone, are then connected with a ssure bur (No. 557 surgical length) or Piezosurgery unit. e depth of the osteotomy should ideally be greater than 2 mm above the man-dibular canal (Fig. 38.24). Vertical Cuts. e anterior vertical cut may then be made and begins in relation to the existence and width of the buccal shelf (extend oblique ridge) of the mandible. Usually the mid-rst molar is in the position of the anterior vertical cut. After the vertical osteotomy approximates the position of the inferior alveo-lar nerve, the osteotomy is limited to the thickness of the buccal cortical plate, usually 2 to 3 mm in thickness. e osteotomy is progressively deepened until bleeding bone from the osteotomy is observed. e anterior osteotomy is usually 10 to 12 mm in length. e posterior osteotomy is then completed, which is usu-ally above and lateral to the inferior alveolar nerve (in front of the lingula on the lingual of the ramus). e posterior osteotomy may be full thickness through the cortical plate to the horizontal osteotomy. Because the mandibular canal in this region is usually inferior or posterior, the osteotomy is made through the entire depth of the cortex (Figs. 38.25 and 38.26). Inferior Cuts. e inferior osteotomy will connect the poste-rior, and anterior vertical cuts may be performed with an oscillat-ing saw, large, round bur (No. 8) in a straight handpiece, or a right angled insert with a Piezosurgery unit. is cut is usually the most dicult because access and visibility are limited. With the inferior cut a shallower cut is made into the cortex to create a line of frac-ture. is inferior cut with a drill should not be made completely through the cortex, because it may be located in close proximity to the mandibular canal. e piezosurgery tip allows preparation of a more dened cut and it does not have the danger of damaging the nerve if it happens to come in contact with any vital structure.Ideally the superior, anterior, and posterior vertical, and inferior cuts should be made continuous so ease of harvesting is accomplished. A thin chisel is gently tapped along the entire length of the external oblique osteotomy, taking care to parallel the lateral surface of the ramus to avoid inadvertent injury to the inferior alveolar nerve. A wider wedge chisel or Potts elevator may then be inserted and levered to pry the bone block segment free and complete the greenstick fracture of the graft from the ramus. After removal of the block, any sharp edges around the ramus are smoothed with a bur or le. A hemostatic dressing (collagen, gela-tin sponge, oxidized cellulose) may be placed into the donor area, and closure of the site may be completed after xation of the graft to the receptor site (Boxes 38.3 and 38.4). Alternative Ramus ProceduresAn alternative option from obtaining a ramus block is the harvest-ing of bone cores with trephine burs. e cores can be xated if large enough or ground down to small particulate pieces that can 1068PART VII Soft and Hard Tissue Rehabilitation ACDBGHFE• Fig. 38.23 (A) The ramus site is the first option for a block graft, especially when the posterior mandible requires augmentation. The incision in an edentulous posterior mandible starts at the retromolar pad and continues to the first premolar. (B) After the full-thickness posterior mucoperiosteal flap is reflected, the incision is extended lateral to the retromolar pad and directly over the bone of the ascending ramus to the height of the occlusal plane. (C) The facial flap is reflected, and the attachment of the buccinator muscle is identified. (D) A periosteal elevator slides along the lateral aspect of the ramus, under the masseter muscle, for a depth of 15 mm. The incision is extended along the ascending ramus when the donor block requires additional length. (E) Ramus retractors are shaped to retract the masseter and curved to allow the preparation of the block at the inferior margin. (F) The facial flap is advanced. Metzenbaum tissue scissors are used in a blunt dissection to create the submucosal space. (G) The host site is prepared for the graft with small holes through the cortical plate, 3 to 5 mm apart. (H) The host site is prepared with a round bur to create a wall of bone at the apical region of the graft. 1070PART VII Soft and Hard Tissue RehabilitationA B• Fig. 38.24 Superior Osteotomy Cuts. (A) Too close to the lateral border, which would result in too thin of a graft. (B) Ideal position that allows for a wider graft.APotential donorsiteBComplete cutthrough cortexC• Fig. 38.25 (A) The ramus donor site is lateral to the molars (buccal shelf region) and extends up the ascending ramus. (B) The ramus donor site uses the outer cortical bone of the ramus and posterior body of the mandible. (C) The top portion of the ramus donor block (green line) is usually above and lateral to the position of the inferior alveolar nerve complex. 1071CHAPTER 38 Intraoral Autogenous Bone Graftingbe used with a membrane graft. Small bone chisels can be used to remove the bone cores. It is hard to collect large volumes of bone using a trephine and harvesting of blocks is probably better suited for most involved graft sites (Figs. 38.27 and 38.28). Tuberosity Donor Sitee maxillary tuberosity has been shown to be a viable intraoral donor source for autogenous bone and a source of osteoprogenitor cells.77,120 e tuberosity bone, although variable in the amount of bone that can be harvested, has been shown to be advantageous in maxillary sinus grafting and ridge augmentation procedures. e cancellous nature of this bone allows it to be shaped and molded. Indications• Horizontalandverticalridgeaugmentation• Threetofourtoothedentuloussites(maximumsize=3×5cm) Advantages• Allowsforlargestaveragesurfaceareaofintraoralgrafts• Noestheticconcerns• Decreasedpainanddiscomfort• Decreasedchanceofincisiondehiscence Disadvantages• Inferioralveolarandlingualnerveinjury• Accessmaybedifcult• Trismus • BOX 38.3 Ramus GraftABCD• Fig. 38.26 (A) The anterior vertical cut is made with a straight handpiece and a fissure bur or oscillating saw. The position is often at the mid-first molar region. The cuts 5 mm above the inferior alveolar nerve (IAN) com-plex are full thickness. (B) The posterior vertical cut is often above and lateral to the lingual and IAN, and there-fore may be made full thickness along the lateral ramus to the superior block margin. The width of the bone block on the superior margin is designed with a small, round bur and ranges from 3 to 6 mm in width from the lateral border. (C) The superior osteotomy is made through the cortical bone and may extend to within 5 mm of the posterior IAN. The horizontal dimension of the ramus block determines the width of the donor site and is related to the amount of bone needed and the anatomy of the donor site. (D) A fissure bur connects the pilot holes of the horizontal cut. This cut is through the cortical plate and may proceed to 2 mm above the IAN.Incision:Initiatesattheleveloftheocclusalplaneintheascendingramus(medialtotheexternalobliqueridge)Extendsanteriorly,avoidingtheretromolarpadSuperior:onexternalobliqueridgealonganteriorborderofthemandibularramus(approximatelyone-thirdwidthofthemandible)Anterior:distalhalfoftherstmolarPosterior:superioraspectoftheexternalobliqueridge(levelofocclusalplane)Inferior: ∼10mminheight • BOX 38.4 Ramus Graft Osteotomy Technique 1072PART VII Soft and Hard Tissue RehabilitationTuberosity grafts may be used as a particulate graft, or in some cases a block graft (Fig. 38.29).Anatomye maxillary tuberosity is dened as the bone at the lower part of the infratemporal surface of the maxilla. It is a rounded eminence that is especially prominent after growth of the third molars. e quality of bone in the maxillary tuberosity is usually considered a very poor type of bone, usually a D4 bone with ne trabeculae and minimal to no cortical bone. e thicker soft tissue in the tuberosity area can be extremely misleading, which frequently results in a misrepresentation of the amount of available bone. e anatomic limitations of this area include the maxillary sinus, pterygoid plates, adjacent teeth when present, and the greater palatine canal. • Fig. 38.27 The ramus is exposed and bone cores are obtained via tre-phine burs.AB CD E• Fig. 38.28 (A) Autogenous ramus harvest block. (B) Harvested cortical ramus block. (C) Block stored in sterile saline. (D) Block reduced to particulate fragments. (E) Particulate fragments placed in the donor site. (From Caldwell CS. Bone grafting complications. In: Resnik RR, Misch CE, eds. Misch’s Avoiding Compli-cations in Oral Implantology. St. Louis, MO: Elsevier; 2018.)• Fig. 38.29 Cone beam computed tomographic panoramic view depict-ing a significant amount of tuberosity bone available for grafting. 1073CHAPTER 38 Intraoral Autogenous Bone GraftingRadiographic AnalysisIdeally a CBCT examination will reveal the quantity of bone present below the sinus. It is imperative to make an accurate assessment of the bone quantity because exposing the maxillary sinus after graft removal may lead to increased complications (Fig.38.30). Incision and Reflectione incision to expose the maxillary tuberosity consists of a crestal incision and a posterior vertical release (45 degrees) from the posterior part of the tuberosity. e incision should never extend onto the lingual contour of the posterior tuberosity or into the hamular notch area because this area is associated with an increased possibility of bleeding episodes. It is important to incise to the bone because in some cases the tissue can be very thick. Donor Site Osteotomy HarvestAfter reection of a mucoperiosteal ap the bone may be har-vested from the tuberosity with a double-action rongeur or chisel. Removing the graft with a chisel will allow the harvest-ing of a larger piece of bone; however, a greater chance of per-foration into the maxillary sinus is possible (Fig. 38.31; Boxes 38.5 and 38.6). AB• Fig. 38.30 Cone Beam Computed Tomographic Cross Section. (A) Significant amount of bone for graft-ing. (B) Minimal amount of bone present that would likely result in a communication with the maxillary sinus.AB• Fig. 38.31 Tuberosity Harvest. (A) Bone removed from tuberosity with a double-action rongeur. (B) Tuberosity bone cores after harvest. 1074PART VII Soft and Hard Tissue RehabilitationBlock Graft PreparationFixation of the Block GraftOnce the monocortical block of bone has been harvested, the recipient site is ready to receive the graft. It cannot be overstressed that for successful graft survival at the recipient site, complete soft tissue coverage must be present that is passive and tension free. If the soft tissue ap has extensive tension, the incision lines will open, resulting in graft exposure and eventual infection of the graft that will result in loss of the bone graft.Soft Tissue Preparatione soft tissue dissection beyond the graft recipient site will help to avoid soft tissue incision line opening and graft exposure. With most bone grafts, soft tissue closure may be challenging. Misch developed a submucosal space technique that helps in overcoming this potential complication. e technique reects a full-thick-ness ap over the graft site and at least 5 mm above the height of the MGJ. e periosteum and soft tissues 5 mm above the MGJ remain on the bone and are not reected. e facial ap is then lifted 3 to 5 mm above the depth of the MGJ and using a scalpel, an incision through the periosteum 1 to 2 mm deep and parallel to the crestal incision extends over and beyond the vertical releas-ing incision. After the incision is made through the periosteum, pointed tissue scissors (i.e., Metzenbaum scissors) may be intro-duced into the periosteal incision for 10 to 15 mm or more, paral-lel to the surface mucosa, with the blades of the scissors closed, so the facial ap thickness is 3 to 5 mm. e tissue scissors are then opened with blunt dissection, which allows the muscles to be separated from the ap and creates a submucosal space. With the periosteum, tissues and muscles attached to the bone are on one side, and a 3- to 5-mm-thick facial ap is on the other side.With this technique the facial ap may now advance the depth of the submucosal space 10 mm or more. is technique greatly increases the ability to advance the soft tissue ap over a large block graft. e advantage of the submucosal space technique is that a split-thickness ap is created and maintains the muscles on the periosteum, which is attached to the bone above the contours of the host site. Because the muscle attachments are the primary source of vascularization to the periosteum and host bone, vascu-larity remains undisturbed. Muscle healing is a primary cause of ap retraction and incision line opening. Because the muscles are no longer attached to the facial ap and the ap may be advanced more than 10 mm, there is no tension on the incision line, which reduces the risk for incision line opening. One complication of the soft tissue procedures to improve graft coverage is the loss of vestibular depth. e reduced vestibular depth is rarely an esthetic concern, and when the restoration is implant retained, the pros-thesis does not rely on a valve seal for primary retention (as in a complete denture). Advancement of the facial ap for graft cover-age may also result in a reduction in keratinized mucosa over the facial aspect of the gingival crest. In some cases, soft tissue or acel-lular dermis grafts may be necessary, or the attached mucosa may be repositioned facially at the stage II implant uncovery surgery (Fig. 38.32). Preparation of the Recipient Sitee next step in graft reconstruction is preparation of the lateral and crestal surfaces of the host and grafted bone using a small-diameter drill equal to or smaller than the drill size of bone screws used to xate the donor bone (i.e., ∼1.4-mm diameter). e ratio-nale for this procedure is to facilitate angiogenesis at the graft site.Drill perforations are 3 to 5 mm apart in the entire area of the graft and host site. Perforations are created under copious amounts of saline and penetrate both the facial and lingual plates of bone in the region of the graft, especially when augmenta-tion is desired on both sides of the residual ridge. is procedure increases the availability of osteogenic cells, accelerates revascu-larization, increases the regional acceleratory phenomenon, and improves graft union96,121,122 (Figs. 38.33 and 38.34). Fixation of the Block GraftAfter the block of bone has been harvested, it can be stored in ster-ile saline solution or immediately xated to the host bone. Mini-mal time should elapse before placement of the block on the host bone.123,124 When placing the bone graft onto the host bone, the cancellous portion of the graft should be in contact with the host bone.81,125,126 Because the graft should passively rest on the host bone, the host bone and harvested block of bone need to be con-toured before graft xation.127,128 e edges of the block of bone can be smoothed with a small, round bur to create a ne, smooth surface that blends in with the surface of the host bone when x-ated with rigid xation screws. Particulate cancellous bone can then be used to ll in any voids between the host bone and har-vested block of bone.When preparing the harvested block of bone, the drill holes on the surface of the block graft are slightly larger than the diam-eter of the rigid xation screws. is permits the rigid xation screws to compress the block graft directly up against the host bone while the screw is threaded completely through both corti-ces (Fig. 38.35). e outer thread of the xation screw is usually 1.4 to 2.0 mm in diameter, with a V-shaped thread design. is allows the screw to thread into the host bone during xation of the graft to the host bone, and removal of the screw at the time of implant placement 4 to 6 months after the graft has remodeled to Indications• Socketgrafting,sinusaugmentation,smallbonydefects• Approximately1–3mL Advantages• Allowsforlargestaveragesurfaceareaofintraoralgrafts• Noestheticconcerns• Decreasedpainanddiscomfort• Decreasedchanceofincisiondehiscence Disadvantages• Entryintomaxillarysinus• Oral-antralstula• Bleeding(posterior-superioralveolar,pterygoidplexus)• Hematoma • BOX 38.5 Tuberosity Bone GraftIncision:midcrestalincisionfromrstmolartoposteriorextentofridge(shortofhamularnotch)Bone harvest:double-actionrongeur,chiselandmallet,Piezosurgery • BOX 38.6 Tuberosity Graft Osteotomy Technique 1075CHAPTER 38 Intraoral Autogenous Bone Graftingthe jaw. e head of the xation screw should be 2.2 mm or more in diameter and at so that it can compress the donor block graft against the host bone.A lag xation screw design should not be used. A lag screw design has smooth metal for 5 to 10 mm below the screw head, and the apical half of the screw has threads. When the screw is placed through the block of bone and host bone, the technique is eective in rigidly xating the block of bone to the host bone (Fig. 38.36). However, when the screw is removed before implant placement, it has been observed that newly regenerated osseous tissue has formed around the smooth portion of the lag screw. is may present problems in removal of the lag screw. While remov-ing the lag screw, the surgeon may have to tap the graft while the screw is being removed. is could lead to loosening of the bone graft from the host bone.ere are many rigid xation screw kits that can be used in bone graft procedures available to the clinician. It is recom-mended that the clinician use self-tapping threaded screws with the tip of the screw pointed and not blunt, to allow penetration into bone. Screw kits come in a variety of screw diameter sizes. e two most commonly used to rigidly xate the block of bone to the host bone are 2.0- and 1.6-mm-diameter screws. After the bone graft has been harvested the next step is stabilizing the graft passively to the host bone and rigidly xating the graft with the use of rigid xation screws, plates, or stainless-steel wires. If using rigid xation screws, two or more screws are required to xate the graft to the host bone that avoids movement. When using only a single rigid xation screw, the block of bone may not be rigidly xated to the host bone. If the graft is not rigidly xated to the host bone, the graft may rotate and move, which will lead to a brous union.e screws are ideally secured to both the facial and the lingual cortical plates. erefore with bicortical stabilization the osteot-omy screw holes must penetrate both facial and lingual cortices. In most cases the host site will need to be altered to allow a passive t for the graft. is is easily accomplished with a small, round carbide (No. 6, No. 8). In addition, the block may be altered with a pear-shaped carbide because the block should have no sharp edges. After recontouring, the donor block of bone is slightly recessed into the host bone 1 to 2 mm, and there should exist no micromovement. With completion of the bone graft procedure, the soft tissues are reapproximated and closed with sutures. After a graft healing period of 4 to 6 months, dental implants may be placed into the graft site. Membranes and Block Graftse use of membranes over autogenous block grafts is controver-sial in the literature. Chaushu etal.129 reported soft tissue com-plications, including membrane exposure (42 [30.7%] of 137), incision line opening (41 [30%] of 137), and perforation of the mucosa over the grafted bone (19 [14%] of 137). Infection of the grafted site occurred in 18 (13%) of 137 bone grafts. Gielkens etal.130 conducted a metaanalysis to investigate the eects of bar-rier membranes on onlay autogenous grafts. ey concluded after a vast systemic review that the available studies are too weak to support the use of membranes. erefore at this time there are insucient data to support the use or nonuse of barrier mem-branes with respect to bone resorption.ABCD• Fig. 38.32 Tissue Preparation for Tension-Free Closure.(A and B) Periosteal release technique with a scalpel. (C and D) Blunt dissection that stretches the periosteum with the use of blunted scissors. 1076PART VII Soft and Hard Tissue Rehabilitation Maturation and Integration of Block GraftsIn most cases, a radiographic survey (e.g. periapical, bite-wings, CBCT) is obtained to evaluate healing approximately 3–4 months after the initial surgery. In conjunction with the radiographic assessment, a clinical examination should be used to evaluate the changes in the grafted ridge contour as well as the tiassue health. Once healing is complete, tissue reection access is obtained to remove any bone screws and allow for ideal implant placement. e autogenous graft should be evaluated for any mobility, which usually is indicative of bone graft failure. (Fig. 38.37, Fig. 38.38). Comparison of Intraoral Bone-Grafting Donor SitesA comparison of intraoral donor sites for onlay grafting before implant placement was reported by Misch.44 e volume of the sym-physeal donor grafts was almost twice as great as ramus sites (1.74 versus 0.9 cm3). e ramus was primarily a cortical graft, whereas the symphysis block was cortical/trabecular. However, the ramus and symphysis donor sites have similar success rates. Aloy-Prósper etal.131 in a systemic review showed the success and survival rates of implants placed into vertical and horizontal defect ridges treated with intraoral block grafts. ey concluded that placing implants into block grafts versus native bone had similar success rates.AB• Fig. 38.33 Soft Tissue Removal. (A) Soft tissue removed with a sharp periosteal elevator. (B) Course carbide in a 1:1 straight handpiece.AB• Fig. 38.34 Recipient Site Decortication. (A) Decortication holes that initiate angiogenesis to heal the graft. (B) Must have bleeding through the decortication holes for the growth factor release.• Fig. 38.35 A lag screw approach is used to fixate the block. The screw slides through the block, and the screw head is larger than the hole in the block. 1077CHAPTER 38 Intraoral Autogenous Bone GraftingClavero etal.120 compared the morbidity and amount of com-plications with ramus and symphysis donor sites. ey deter-mined although the symphysis has better accessibility, the ramus donor site allows for a greater amount of harvested bone, with higher bone density and more cortical content, together with fewer complications.Gultekin etal.132 studied the dierence in bone loss between autogenous block grafts and guided bone regeneration (GBR). ey concluded that both the block graft group and GBR group provided sucient volume of bone for implant placement. How-ever, the GBR group did show greater bone resorption in com-parison with the autografts.Yates etal.133 compared the harvested volume of the ramus ver-sus the symphysis and also the associated morbidity. ey deter-mined that the ramus can provide the greatest volume of bone and signicantly less morbidity in comparison with symphysis bone grafting (Table 38.1). Postoperative Care and InstructionsAn increase in incision line opening has been associated with post-operative smoking and diabetes in patients with autografts.26,134 Patients should stop smoking at least 3 days before surgery and at a minimum until the incision line has healed. It is imperative that the graft be immobilized during healing and there exists no exter-nal pressure on the graft. Removable soft tissue–borne prostheses should not be worn or should be adjusted to prevent graft loading. e ange area of a removable prosthesis should be completely removed, and the edentulous ridge area is generously relieved, which requires the patient to use denture adhesive for prosthesis retention. However, the denture adhesive should not be placed over the incision line. e patient is instructed to use the provi-sional removable prosthesis for cosmetic appearance only rather than function.Careful postoperative follow-up is necessary to inspect the bone graft region and eliminate pressure areas from an overlying pros-thesis. More favorable provisional solutions are tooth-borne xed or removable partial dentures, resin-bonded bridges, or denture teeth bonded to the adjacent dentition.135 e use of transitional implants to support a xed-interim prosthesis during the healing phase may be considered for patients less tolerant of removable provisional restorations.136,137 ComplicationsSymphysis Graft ComplicationsIncision Line OpeningMany factors predispose the symphysis donor site to incision line opening. If a vestibular incision is used, a two-layered suture technique is recommended. A suture with a high tensile strength should be used (e.g., Vicryl, PTFE) to maintain the integrity of the incision line. e patient should be instructed not to pull on the lower lip to evaluate the surgical site because this will increase the chances of incision dehiscence. Misch138 determined that • Fig. 38.36 The screw should fixate each bone block. The screws should engage the lingual plate of the host site. Comparison of Intraoral Donor SitesCriteria Symphysis Ramus TuberositySurgical access Good Fairtogood FairtogoodPatient cosmetic concern High Low LowGraft shape Thick Thinveneer ThintothickGraft morphology Cortico-cancellous Cortical CancellousGraft size (cm) 5–15 5–10 ∼5Graft resorption Minimal Minimal ModerateHealed bone quality D1,D2 D1,D2 D3,D4Donor Site ComplicationsPostoperative pain/edema Moderate Minimal MinimalNeurosensory: teeth Common(temporary) Uncommon UncommonNeurosensory: tissue Uncommon(temporary) Uncommon UncommonIncision dehiscence Occasional(vestibular) Uncommon Uncommon TABLE 38.1 1078PART VII Soft and Hard Tissue Rehabilitationdehiscence of the donor site occurred in 10.7% of anterior man-dibles because of function of the mentalis muscle, and no incision line opening was found in the posterior mandible or ramus donor sites. Neurosensory ImpairmentNeurosensory decits of the third branch of the trigeminal nerve are rare in association with symphysis grafts. However, it is a common sequela to have neurosensory changes in the mandibular anterior teeth. Because the second terminal branch of the inferior alveolar nerve (incisive branch) terminates in the anterior mandibular area, it is not uncommon to sever this section of the nerve during osteotomy preparation. However, because the incisive nerve is only a sensory nerve to the inci-sor teeth, this usually results in only a “dullness” in sensation. Hoppenreijs etal.139,140 showed a negative pulpal response in 16% of patients after a symphysis graft, with total resolution in 6 to 12 months.Usually a neurosensory impairment of the mandibular ante-rior teeth does not result in a painful sensation, but it is disrup-tive, causing patients to generally describe the incisors as having a “woody feeling.” is series of complications can usually be avoided by refraining from aggressive harvesting of medullary bone surrounding the donor site.Studies have shown the incidence of neuropraxia after the har-vesting of block grafts from the ramus versus the symphysis. After 18 months, more than 50% of the patients with harvest sites in the symphysis still had altered sensation. None of the patients in the ramus donor group reported any symptoms at 18 months.141e superior portion of the harvest site should be prepared at least 5 mm below the level of the incisor root tips to prevent a neurosensory impairment. Care must be taken to avoid the longer roots of the cuspids as each end of the harvest pattern is prepared. Aggressive harvesting of the medullary portion of the symphysis should be minimized in the superior aspects if possible to limit damage to neural pathways through the region. Most importantly, complete patient education must be conducted “before” the sur-gery informing the patient about potential sensory changes that could occur. e patient should be aware that he or she could feel a dullness or “woody” feeling of the mandibular anterior teeth after surgery. is can be temporary or a permanent condition, but it has never been described as a particularly annoying feeling. Rarely is there an indication for endodontic therapy, as the vitality of the teeth returns to normal. Bleeding EpisodesWhen a cortical graft and the surrounding medullary bone are harvested in the symphyseal region, the underlying neurovascu-lar components are often compromised. ese disruptions to the nerves and blood vessels may be accompanied by possible signi-cant bleeding immediately after the graft harvest.AB• Fig. 38.37 (A). Two blocks of cortical bone have been fixated on the lateral aspect of the posterior mandibular ridge with fixation screws. Med-ullary particulate has been used to fill the voids around the block grafts. (B). The mineralized block grafts after five months of healing. Note the smooth surface of the final graft and the nature of the intertwined recipient site and the grafted blocks.BA• Fig. 38.38 (A). This 3 D image shows the severe bony defect resulting from removal of a blade implant. This vertical defect extends to the level of the mandibular canal. (B). Five month postop matured block graft site that was supplemented with particulate around the remaining defects. Note the density of the final bony structure. 1079CHAPTER 38 Intraoral Autogenous Bone Graftinge incisive nerve is the second terminal branch of the inferior alveolar nerve that provides innervation to the mandibular teeth. e incisive nerve path between the mental foramina has been known to be a safe zone for bone harvesting because of the lack of vital structures that can be aected by grafts taken from this region. A thorough understanding of the neurologic and vascular anatomy in this region is critical for the prevention of complica-tions during and after surgery in the symphyseal region. Aggres-sive graft harvesting in this area may give rise to a lingual plate perforation, which leads to possible signicant bleeding issues and airway management complications.e sublingual arteries may also cause signicant bleeding if the lingual plate is perforated. e incisive neurovascular bundle is found to join other vascular structures in the midsymphyseal region. e genioglossus muscle attaches to the genial tubercle in the midline, and the sublingual artery courses through the lingual foramen at the genial tubercle. e lingual artery is approximately 1 to 2 mm in diameter, and cross-sectional views clearly show its anastomosis with the incisive canal at this point.e preparation of a grafting osteotomy in the midline can potentially resect these blood vessels if they fall in the path of the vertical preparation. If this occurs, the sectioned extension of the lingual artery can prolapse back into the oor of the mouth. e severed vessel may release arterial blood ow in the sublingual space, potentially raising the tongue to a point that compromises the airway. Immediate emergency intervention to maintain the airway is critical, and in some cases this requires use of a tracheostomy until the blood ow has been controlled (Fig. 38.39). PtosisOne of the main patient concerns when confronted with the pros-pect of symphysis grafting is a change in facial or soft tissue appear-ance. e idea of having a permanent bony chin defect or ptosis contributes to a patient’s apprehension regarding this procedure.e main concern of patients after a symphysis graft is a post-operative change in the soft tissue contour of the chin. In the liter-ature there exists no evidence of a statistically signicant incidence of dehiscence or chin ptosis after a symphysis graft. To minimize the possibility of ptosis, avoid degloving the mentalis muscle by maintaining the facial and inferior aspects of the mandible and the lingual aspect of the inferior border of the mandible during ap refection. In addition, to prevent lower lip height reduction and vermilion zone inversion, the integrity of the periosteum to the inferior reection should not be deeper than one-third of the total distance from the vermilion border to the MGJ. An extraoral bandage or pressure dressing may be used postoperatively for sup-port and to help with compression of the wound. Ramus Graft ComplicationsNeurosensory DeficitPatients have also shown less concern with bone removal from the ramus area, and augmentation of this donor site is unneces-sary. Although vestibular incision dehiscence has occurred with symphysis grafts, it is usually not a common occurrence in the ramus donor site. Patients are less able to discern neurosensory disturbances in the posterior buccal soft tissues compared with the lower lip and chin. Although the incision along the exter-nal oblique ridge may injure the long buccal nerve, reports of postoperative neurosensory decit in the buccal mucosa are less frequent and will most likely go unnoticed by the patient.142,143 In contrast with the teeth superior to the symphysis donor site, patients have reported minimal altered sensation in their molar teeth.44,144Damage to the inferior alveolar neurovascular bundle could also occur during harvesting of the graft in the ramus area of the mandible. When using bone chisels or elevators, the instru-ments must parallel the lateral surface of the ramus to avoid a nerve impairment. If the inferior ramus cut is below the level of the inferior alveolar canal, graft separation should not be com-pleted until it can be veried that the neurovascular bundle is not trapped within the graft. Although nerve injury to the inferior alveolar nerve is low, patients should be aware of this risk during the consultation before surgery.On occasion the inferior alveolar nerve is identied and directly observed when the block graft is removed from the ramus. When this occurs, dexamethasone (Decadron) 4 mg (1 cc) may be placed BA• Fig. 38.39 (A) Cross-sectional image depicts fractured symphyseal plate from poor patient selection of a symphysis graft. (B) Axial view. (From Cordaro L, Rossini C, Mijiritsky E. Fracture and displacement of lingual cortical plate of mandibular symphysis following bone harvesting: case report. Implant Dent. 2004;13:202-206.) 1080PART VII Soft and Hard Tissue Rehabilitationdirectly on the nerve for 30 seconds to reduce inammation and edema. A second dose of 4 mg (1 cc) then is applied for an addi-tional 30 seconds. A collagen sponge may be placed over the site, but hydroxyapatite or graft material is not indicated (Figs. 38.40 and 38.41). Bone Graft ComplicationsIncision Line Opening in Bone-Grafting SitesMaintenance of complete soft tissue coverage over healing bone-grafting sites is one of the most important principles that must be observed for predictable grafting success.Anytime that the healing graft site is exposed to the oral ora during the healing process, there will be some type of compro-mised change in the nal graft site volume and in its overall integ-rity. Incision line opening with compromised graft results can often be a major limiting factor in successful implant placement.Incision line opening can compromise even the most care-fully planned regeneration site, and most of these graft sites will require additional grafting at a later time if an actual compli-cation develops. An open incision line introduces numerous potential complications into the healing process. First, the intro-duction of microorganisms into a graft site through an open incision leads to an infection in the healing graft site. Exposure of the block graft and accompanied graft particles accompanied by the presence of purulence is an indication of impending fail-ure of the graft. e infection reduces the pH in the graft site, causing a breakdown of the graft and eventually compromising the resulting ridge volume. Second, an open incision line may allow exposure and breakdown of any barrier membranes, con-tributing to brous tissue ingrowth into the graft site. Lastly, there exists a potential for particulate graft materials that have been packed around the circumference of the block to escape the graft site, resulting in an inadequate bone volume in the nal proposed implant site.145Tension-free tissue coverage is the most critical variable in pre-venting incision line opening. A clinician’s experience in manipu-lation of soft tissue aects this aspect of bone regeneration more than any other part of bone regeneration surgery. As the clini-cian gains more experience in delicate tissue management and begins to understand the maintenance of a tension-free ap clo-sure, problems with graft and membrane exposure will become an uncommon occurrence.e inner surface of a reected ap is lined with the perios-teum: a thin, dense layer of tissue that cannot be stretched. It is impossible to stretch the soft tissue ap over a graft site without rst severing this layer of tissue. is “tissue release” is accom-plished by preparing a clear and continuous releasing incision through the periosteum, exposing the underlying elastic layers of tissue that can then be released for expansion of the ap over the enlarged graft site. As this incision perforates the periosteal layer, the two edges clearly separate, allowing the elastic tissue below the periosteum to stretch. A sharp pair of Metzenbaum scissors is then placed into the space below the periosteum, and as the scissor tips are opened, the tissue easily releases and the edges separate farther. is is repeated until the complete ap is stretched over the graft site and 5 mm beyond the opposite ap margin.In the event of an incision line opening, the patient should be placed on a frequent monitoring protocol to observe the status A B• Fig. 38.40 (A) On occasion the inferior alveolar nerve complex can be identified after the block is removed. (B) When this occurs, dexamethasone (Decadron) 4 mg (1 cc) may be used directly on the nerve to reduce inflammation.• Fig. 38.41 Large donor graft site leading to exposure of the inferior alveolar nerve (arrow) with associated neurosensory impairment. (From Caldwell CS. Bone grafting complications. In: Resnik RR, Misch CE, eds. Misch’s Avoiding Complications in Oral Implantology. St Louis, MO: Elsevier; 2018.) 1081CHAPTER 38 Intraoral Autogenous Bone Graftingof the graft material and any grafting hardware present. e oral microora must be managed with the use of daily chlorhexidine rinses. e clinician must not attempt to suture the site again because healing margins along incision lines feature tissue that cannot, at that time, support the pressure of another suture under tension.If graft dehiscence occurs, the wound should be allowed to heal by secondary intention. Resuturing an incision line open-ing is rarely successful and will usually result in a larger dehis-cence. e block graft may be recontoured with a diamond bur to reduce the bulk of exposed bone. e bone above the margins of the surrounding tissue is ground o, which also removes the biolm. is procedure is repeated every 2 to 4 weeks until the site is closed (Figs. 38.42 and 38.43). Mobility of the BlockMobility of an autogenous graft during the healing process will almost always result in a graft failure. Mobility of the block pre-vents proper integration of the newly forming bone, and even-tually it will lead to soft tissue invasion between the block and the recipient site. Rigid xation of the block graft to the recipi-ent bone site is critical for success in the regenerative process. Although regeneration with block grafting is related to the con-cept of “barrier by bulk,” micromovement will often contrib-ute to a weak bond between the cortical graft and the recipient site. is will potentially cause the block to separate from the ridge as pressure is placed on the interface between the native bone and the integrated block as a result of the implant being inserted into the osteotomy. e most common cause for graft mobility is insucient xation or pressure from a prosthesis postoperatively.Initial xation of a block graft must be attained when the block is originally placed in the recipient site. Any movement of the block during the healing process will disrupt the formation of a stable clot around the migrating cells, and a loose block will not integrate into the host bone. Ideally two xation screws should be used in every block graft, eliminating any micromovement of the block during the healing process.e recipient site should be prepared for close approximation of the surface of the block graft to the recipient site. e block should be inlaid into the recipient site, and particles of medul-lary bone or allograft should be packed around the circumference, lling any discrepancies. e temporary prosthesis should be adjusted to prevent any contact with the graft site, and the buccal ange should be removed on any removable appliance to limit micromovement.Fixation screws should be engaged into the underlying bone enough to provide rigid support of the graft. A longer shaft on AB• Fig. 38.43 Consequences of Resuturing an Incision Line Opening. (A) Incision line opening 2 weeks after surgery and treated with resuturing. (B) Six weeks postresuturing showing significant incision line opening.A B• Fig. 38.42 (A) Incision line opening or block dehiscence is a complication of block bone grafts. (B) The soft tissue should not be resutured over the graft that dehisces during the first few months. Instead, the block is recontoured so the bone above the tissue margins is removed. The area is left to heal by second-ary intention. 1082PART VII Soft and Hard Tissue Rehabilitationthe supporting screw may be necessary to obtain ridge xation in soft bone. e screws should have a self-threading tip, and the preparation hole should be prepared deep enough to prevent the shaft of the screw from bottoming out in dense cortical bone. Excess insertion pressure on a screw passing into very dense bone without adequate depth preparation can contribute to the head of the screw snapping o during its insertion. Most updated xa-tion screws have a pointed self-threading screw tip that helps with screw insertion.If micromovement of the block graft occurs during sur-gery, the block should be removed and the screws should be replaced with longer or wider fixation screws. If the move-ment occurs during the healing phase, the block should be monitored carefully; however, most likely it will need to be removed (Fig. 38.44). Soft Tissue Irritation From an Overextended FixationScrewBone xation screws are routinely placed in the bony ridge for various reasons during implant-related surgery. It is not uncom-mon to discover the end of a screw extending beyond the lingual or palatal cortical plate. When this occurs, there is a potential for the overextended screw to cause discomfort. Overextended screws can be a source of irritation to the thin soft tissue on the lingual aspect of the mandible. e movement of the thin mucosa and tongue against the sharp point of the screw can cause quite a bit of discomfort. is is not usually an issue in the maxilla, where the thicker nature of the palatal tissue acts as a protective buer.To prevent this complication, screw placement should be followed by both a visual inspection of the opposing surface of cortical bone and a digital review of any potential problems areas that will need correction. e only way to treat an over-extended screw involves reection of a ap to provide access for removal of the overextension or removal of the complete screw. Screw removal is not usually a reasonable solution because that would require reection of the tissue overlying the maturing graft site and disruption of the graft as the screw is removed (Fig. 38.45). Implant PlacementBecause mandibular donor grafts exhibit minimal resorption, predictable gains in bone volume allow implant placement in most planned sites. A staged treatment plan with implant place-ment after graft healing is the preferred method of reconstruc-tion. Reports on simultaneous implant insertion during bone graft placement have revealed complications, such as block graft fracture, wound dehiscence with exposure of implants and graft, and a higher implant failure rate compared with a staged approach.38-40,46,55,146 In addition, diminished bone contact has been found around titanium implants placed simultaneously with autologous grafts.12,30,85,147 A staged surgery permits implant placement for ideal prosthetic alignment without the concern of graft xation or remodeling. Staging the implant placement also provides an improved vascularity of the transplanted bone as the exposed surface area is increased and unimpeded by an inert biomaterial.53,148 It also allows for any unanticipated increase in graft resorption and should provide a more stable foundation. e implant-bone interface should be improved, because the implant surface is in close contact with the already incorporated bone graft. Autologous bone grafts oer an improved quality of bone at earlier healing times compared with allogeneic bone grafts or guided bone regeneration techniques.38,58,87,149-151 e density of healed block mandibular bone grafts has been found to be D1 to D2 regardless of the original quality of the recipient site.38,44,58 An appropriate drilling sequence for dense bone and ABC• Fig. 38.44 Prevention of Graft Mobility. (A) Two screws need to be placed to prevent micromovement during healing. (B) The donor site needs to be prepared to minimize “rocking” of the graft when fixated. (C) Block graft securely fits into host site. (From Caldwell CS. Bone grafting complications. In: Resnik RR, Misch CE, eds. Misch’s Avoiding Complica-tions in Oral Implantology. St Louis, MO: Elsevier; 2018.) 1083CHAPTER 38 Intraoral Autogenous Bone Graftingtapping may be necessary for atraumatic implant placement. e implant surgery activates bone formation and induces interfacial remodeling with bone maintenance, even in unloaded condi-tions.152,153 After integration a progressive bone loading of the implants is recommended.154 Additional graft resorption after implant insertion has not been noted radiographically on loaded cases.155-158 SummaryAutologous bone grafts are the only type of graft material that heals via osteogenesis, osteoinduction, and osteoconduction. Bone har-vested from the maxillofacial region oers several advantages in the reconstruction of the residual ridge for implant placement. Intra-oral donor sites require only one operational eld, which decreases ADBC• Fig. 38.45 Screw Overextension. (A) When screw extends through the lingual plate (arrow), this will often result in pain and discomfort for the patient. (B) Preoperative evaluation for fixation screw. (C) Ideally the fixation screw should exhibit bicortical stabilization, and the length measurements may be determined via cone beam computed tomographic measurements. (D) The protruding tip of this fixation screw has been visualized. (From Caldwell CS. Bone grafting complications. In: Resnik RR, Misch CE, eds. Misch’s Avoiding Complications in Oral Implantology. St. Louis, MO: Elsevier; 2018.) 1084PART VII Soft and Hard Tissue Rehabilitationthe surgical and anesthetic time. Larger block bone grafts may be harvested from the mandibular symphysis, body, or ramus area. Particulate autograft may be harvested from the maxillary tuber-osity, extraosseous tori, ridge osteoplasty, extraction sites, implant osteotomy, and bone collection devices. ese grafts require a short healing period and exhibit minimal resorption, while maintaining their dense quality. e morbidity of graft harvest is low, and com-plications usually result in only temporary debilitation. e use of these techniques allows the placement of implants in ideal positions for optimal esthetics and functional support.References 1. Misch CE, Dietsh F. Bone grafting materials in implant dentistry. Implant Dent. 1993;2:158–167. 2. Buser D, Bragger U, Lang NP, etal. Regeneration and enlargement of jaw bone using guided tissue regeneration. Clin Oral Implant Res. 1990;1:22–32. 3. Lekholm U, Becker W, Dahlin C, etal. e role of early vs. late removal of GTAM membranes on bone formation around oral implants placed in immediate extraction sockets: an experimental study in dogs. 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