Maxillary Anterior Implant Placement










706
29
Maxillary Anterior Implant
Placement
RANDOLPH R. RESNIK AND CARL E. MISCH
*
Maxillary Anterior Implant Placement
Contrary to missing a posterior tooth, most patients have an
emotional response regarding a maxillary anterior missing tooth.
Because the premaxillary teeth are directly within the smile line,
no question exists regarding the need to replace the tooth, and
nancial considerations are usually less important. When poste-
rior teeth are extracted, little resistance to the preparation of adja-
cent teeth may be given to the dentist. However, when anterior,
normal-looking teeth must be prepared to serve as xed partial
denture (FPD) abutments, the patient is more anxious and often
looks for an alternative. In the patients perspective, anterior FPD
prostheses are never as esthetic as natural teeth. is in part is
because they are able to distinguish between the esthetics of a nat-
ural tooth versus a porcelain/zirconia restoration.
erefore the profession and patients are gravitating to implant
replacement instead of conventional prosthetics. Single-tooth
implants are now one of the most common implant procedures
performed in the United States. In the nonesthetic posterior
region, the single-tooth implant is one of the simplest procedures
in implant surgery and prosthetics. However, it should be noted,
the maxillary anterior single-tooth replacement is often the most
dicult procedure in all of implant dentistry.
e highly esthetic zone of the premaxilla often requires both
hard (bone and teeth) and soft tissue restoration. e soft tissue
drape is usually the most dicult aspect of treatment to develop
and maintain. As a consequence, maxillary anterior single-tooth
replacement is often a signicant challenge, regardless of the expe-
rience and skill of the clinician.
Maxillary Anterior Implant Studies
In general, the single-tooth implant has the highest success rate
compared with any other treatment option to replace missing
teeth with an implant restoration (e.g., short-span FPD, full-arch
FPD, single-tooth implant).
1-4
Misch and colleagues reported on
276 anterior maxillary single implants used to restore missing
teeth from agenesis. In 255 adolescent patients, the implants were
monitored for a range of 2 to 16 years, with a 98.6% implant and
crown survival rate.
5
In the same year, Wennstrom and colleagues
reported on a 5-year prospective study with 45 single-tooth
implants, with a 97.7% implant survival rate with minimal bone
loss.
6
In 2006, Zarone and colleagues reported on lateral maxil-
lary agenesis replacement with 34 implants, with a 97% survival
rate at 39 months.
7
A review of the literature by Goodacre and
colleagues found that single-tooth implant studies had the highest
survival rate of any prosthesis type and averaged 97%.
8
erefore
the maxillary anterior implant has been well researched and most
studies show a very high success rate.
More recently, a trend toward single-stage and immediate-
placement implants has emerged, appearing especially attractive
in the maxillary anterior region. is is preferable because the
soft tissue drape is easier to retain, and with this type of treat-
ment shorter treatment time is advantageous. Kemppainen and
colleagues in a prospective study of 102 single-tooth implants in
the anterior maxilla, reported a 99% success rate using one- and
two-stage implant protocols.
9
Other studies have recommended
one-stage and immediate load with overwhelming success.
10,11
Maxillary Anterior Teeth Evaluation
e maxillary anterior implant is successful only if the nal resto-
ration it supports is fully supported functionally and esthetically
with the adjacent dentition. e exponential growth of the eld
of implant dentistry has been paralleled by exciting new advance-
ments in esthetic dentistry and plastic regenerative surgery. is
growth has made the profession realize that the restoration of the
peri-implant soft and hard tissue to an optimal architecture is the
key to a successful implant restoration. It is no longer acceptable
practice to only achieve osteointegration with an implant. e
implant restoration complex in the esthetic zone should ideally be
achieved in a context that respects all biological tissues (Fig. 29.1).
When the goal for a maxillary incisor single-tooth replacement
is to obtain an ideal result, the clinician should rst evaluate not
only the edentulous site but also the remaining anterior teeth.
Because only one tooth is missing, the adjacent teeth most often
dictate its length, contour, shape, and position. If this is not sat-
isfactory, then a potential modication may need to be integrated
into the overall treatment plan.
Parameters for a healthy esthetic anterior restoration have
been established. e following guidelines have been proposed
by esthetic and cosmetic dentistry colleagues. ese parameters
*
Deceased.

707
CHAPTER 29 Maxillary Anterior Implant Placement
play a determinant role in the nal result and should not be over-
looked. e patient must be educated about their present condi-
tion before the onset of treatment, and the starting point should
be documented. e patient, once fully informed of the existing
discrepancies and their potential negative eect on the envisioned
result, may decide to address and correct the existing problems
of the adjacent teeth or simply elect to accept the compromise.
Correction may be as simple as bleaching the remaining teeth or
as complex as full esthetic rehabilitation with crown lengthen-
ing, soft tissue plastic surgery, veneers or crowns, and orthodontic
therapy (or a combination of these procedures).
Maxillary Tooth Size
e two maxillary central incisors should appear symmetric and
of similar size, most importantly when the patient has a high
smile line. is is most critical to evaluate when the missing tooth
is one central incisor (Fig. 29.2). Outline asymmetry is visu-
ally acceptable the more distal from the midline the eye travels.
When one maxillary tooth is missing, the remaining space may
be compromised from drifting of the adjacent teeth. Orthodontic
intervention may be indicated when the missing tooth is a cen-
tral incisor with a mesiodistal space less or more than the size of
the corresponding central incisor. e other option is to modify
the existing central incisor with a veneer or composite to make it
similar in size and shape to the missing tooth restoration. is has
the advantage of lowering the mesial interproximal contact and
making the two centrals more square shaped, which decreases the
height requirement of the papilla. e shades of the two centrals
is easier to match when made at the same time in the laboratory.
To understand ideal tooth size, the clinician should have a clear
understanding of the normal and average tooth dimensions.
Central Incisor. e average clinical crown length of the maxil-
lary central incisor is 10.2 mm for a male patient and 9.4 mm for
a female patient.
12
In some cases, surgical crown lengthening and
longer anterior teeth may be indicated to reduce gingival exposure
during a high-smile lip position. Because the clinical crown height
of an implant-supported central incisor is often longer than the
adjacent tooth, an esthetic crown lengthening on the natural tooth
may be used to align the gingival margins. When an implant crown
is longer than the corresponding natural tooth, a crown-length-
ening procedure may be more predictable on the natural tooth
than attempting to augment the implant crown with soft tissue.
However, the clinical crowns of natural teeth are rarely more than
12 mm high. e width of the average maxillary central is 8.6 mm
for a male patient and 8.1 mm for a female patient. Although male
teeth are usually slightly longer and wider, the length to width
ratio is similar to female teeth, (0.85 for male patients and 0.86 for
female patients). A ratio range of 0.70 to 0.86 has been reported to
be acceptable for the central incisors when they are similar. When
the anterior teeth are made longer and both centrals have the same
width, an acceptable result may be obtained.
Lateral Incisor. e average clinical crown length of the maxil-
lary lateral incisor is 8.7 mm for a male patient and 7.8 mm for a
female patient. erefore the average lateral incisor is almost 1.5
mm shorter than the central incisor (at both the gingival region
and the incisal edge). Gingival margins of the maxillary lateral inci-
sors may be similar to centrals and canines, but they should not be
higher than the neighboring teeth. erefore an implant crown on
the lateral incisor should not be longer than the central or canine.
e average width of a lateral incisor is 6.6 mm for a male patient
and 6.1 mm for a female patient, but this is more variable than
for any other anterior tooth. e length to width ratio is slightly
greater for a female patient (0.79, compared with the male patient
ratio of 0.76). A lateral incisor space may be slightly narrower than
the other natural tooth; however, when replacing the lateral incisor,
it may be preferable to perform a slight mesial stripping of the adja-
cent canine to duplicate and make symmetric the lateral incisors.
Canine. e average male canine clinical crown length is 10.1
mm and width is 7.6 mm, with a ratio of 0.77. e canine is usu-
ally the same height as the central but 1 mm narrower. Usually the
lateral incisor is 1 mm narrower than the cuspid. e female canine
height averages 8.9 mm (0.5 mm shorter than the central) and 7.2
mm in width (1 mm narrower), with a ratio of 0.81. As a general
rule, regardless of sex, the central incisor is 2 mm wider than the lat-
eral incisor and 1 mm wider than the canine. However, on the hori-
zontal plane, the canine is 1 to 2 mm shorter than the central incisor
and corresponds to the curvature of the lower lip during smiling.
Tooth Shape
ree basic shapes of maxillary anterior teeth exist: (1) square, (2)
ovoid, and (3) triangular. e tooth shape will directly inuence
the interproximal contact area and the gingival embrasure. e
Fig. 29.1 Maxillary anterior implants that may be functional; however, in
some situations (i.e., high smile line) they may not be esthetically pleasing
to patients because of the addition of pink porcelain between the lateral
and central incisor.
Fig. 29.2 Patient’s left maxillary central incisor was replaced with an
implant and crown. The tooth is wider than the right central incisor. Ortho-
dontics could have reduced the horizontal overjet of the lateral and central
incisors and resulted in more symmetric teeth. A second option is a veneer
on the right central incisor to correct the rotation and make the natural
tooth more symmetric to the implant crown.

708
PART VI Implant Surgery
square tooth shape is the most favorable to obtain an ideal soft
tissue drape and papillae around the crown because the interproxi-
mal contact is further apical and more tooth structure will ll the
interproximal region. In contrast, a triangular tooth shape has a
more incisal interproximal contact, a steeper gingival scallop, and
is farther from the interproximal bone (Fig. 29.3). As a result, a
space often exists between the interproximal contact and the inter-
dental papilla of the remaining teeth. is is especially noteworthy
to observe at the initial examination. When the soft tissue lls the
interproximal space of the remaining anterior teeth that have a
triangular shape, the tissues may be very liable and easily disap-
pear during the healing phases after implant surgery. Care should
be taken if the adjacent soft tissue requires reection for a bone
graft before the implant insertion. e ideal restoration of the soft
tissue with a triangular-shaped tooth is less predictable.
e cervical embrasure of the adjacent teeth to the edentulous
site should be particularly evaluated. A triangular tooth is narrow
at the cervical embrasure, and the base of the interproximal tissue is
wide. In addition, the adjacent tooth contact is often higher o the
tissue, with an increased risk of a black triangular space. When such
a condition is present on the adjacent teeth of the missing tooth, it is
likely that the interdental papillae region will also be compromised
on the implant crown. e tooth shape also aects the topography
of the underlying hard tissues. e roots of triangular tooth shapes
are positioned farther apart; therefore they have thicker facial and
interproximal bone. is may decrease the amount of crestal bone
loss after an extraction. In addition, the prognosis for an immediate
implant insertion is more favorable in these situations because the
bone defect is smaller in diameter and the interproximal bone more
likely to provide the recommended 1.5 mm or more of interproxi-
mal bone from the adjacent tooth. e square-shaped tooth is more
likely to have less interproximal bone between the roots. erefore
it presents a greater risk of crestal or interproximal bone loss with an
immediate implant insertion, making it less favorable for immedi-
ate implant insertion after extraction.
Soft Tissue Drape
e height of the maxillary lip when smiling (high lip line) is one
of the most important criterion to evaluate when observing the
cervical region of the maxillary anterior teeth. Its position is usu-
ally related to age, with older men showing the least amount of
teeth and soft tissue and younger female patients displaying the
most. Some patients (15% of male patients and 6% of female
patients) show only the incisal half of the anterior teeth when
they smile.
13
ose patients should be identied and it should be
explained in detail that an ideal soft tissue result in the gingival
region is not mandatory. Clinical results in emergence contours,
interdental papilla presence, and even shade and contour of the
crown are much less demanding. erefore the additional surgical
intervention and cost may not be necessary when these patients are
willing to accept a slight compromise in ideal esthetics (Fig. 29.4).
Ideally the height of the maxillary lip should rest at the junc-
tion of the free gingival margin on the facial aspect of the maxil-
lary centrals and canine teeth.
14,15
us the interdental papillae are
visible, but little gingival display is seen over the clinical crowns.
Almost 70% of patients have this ideal smile position. A “gummy”
smile is dened as showing more than 2 mm of soft tissue above
the clinical maxillary crowns and is more acceptable in the female
patient. It may occur in more than 14% of the female population
and 7% of the male population. e higher the high lip line, the
more ideal the esthetic requirements are for the remaining teeth
and the single-tooth replacement. erefore the existing maxillary
anterior teeth condition is closely scrutinized when a high lip line
exists and ideal results are desired.
e soft tissue drape of the remaining teeth should be evalu-
ated, especially if exposed during the high lip position of smiling.
Under ideal conditions, soft tissue completely lls the interproxi-
mal space, with no dark triangles from the absence of light within
the oral cavity. e interproximal contact between the maxillary
central incisors should begin in the incisal third of the teeth and
Fig. 29.3 Triangular tooth shape has the steepest gingival scallop, and
the interproximal bone is farthest from the tip of the papilla. After an extrac-
tion, shrinkage of the tissue makes the soft tissue drape in this tooth shape
the most difcult to restore.
A
B
Fig. 29.4 (A) The maxillary left central incisor was restored with an
implant restoration. The patient desired a soft tissue graft to cover the
implant crest module. (B) The high lip position during smiling did not dis-
play the cervical region of the patient’s central incisors. Although this is
not an ideal result, additional surgeries would not improve the crown’s
appearance within the esthetic zone, and the soft tissue pocket created
may increase the risk of peri-implantitis.

709
CHAPTER 29 Maxillary Anterior Implant Placement
continue to the height of the central interdental papilla. In a
healthy patient, very little to no space is seen between the papillae
and interproximal contact. According to Kois, the distance from
the facial free gingival margin to the height of the central midin-
terproximal papilla is usually 4 to 5 mm; therefore the interden-
tal papilla height is approximately 40% to 50% of the exposed
tooth length.
16
Interproximal contacts at the incisal position start
progressively more gingivally from central to canine. e greatest
papilla height is often between the centrals, slightly lower between
the centrals and laterals, and even lower between laterals and
canines (Fig. 29.5).
However, the papilla height is often similar between the cen-
trals and from the centrals to the laterals. Under ideal conditions
the osseous scallop of bone in the maxillary anterior region begins
2 mm below the cement-enamel junction (CEJ) midfacial to a
point 3 mm more incisal in the interproximal region. e soft tis-
sue follows this osseous scallop. A soft tissue biological dimension
of approximately 3 mm in height above the bone is present at the
midfacial position (1 mm above the CEJ) and 3 to 5 mm above
the interproximal bone. erefore if the interproximal contact is
within 3 to 5 mm of the interproximal bone, then the interdental
papilla will most often completely ll the space. Tarnow and col-
leagues
17
and Norland and Tarnow
18
measured the distance from
the bottom of the interproximal contact to the vertical height of
interproximal bone on natural teeth and observed how frequently
the interproximal space would be completely lled by soft tissue.
e distances ranged from 3 to 10 mm, with 88% of the contacts
to the bone at 5 mm, 6 mm, or 7 mm; the most common mea-
surement was 6 mm (40%), followed by 5 mm (25%), and then 7
mm (22%) (Fig. 29.6).
When the contact point to bone was 3 to 5 mm, the papilla
almost always lled the space. When the contact was 6 mm, an
absence of papilla was noted almost 45% of the time; at a 7-mm
distance the papilla did not ll the space 75% of the time (Fig.
29.7). In other words, a dierence of 1 to 2 mm from the interprox-
imal contact to the interseptal bone is very signicant in relation to
the interproximal soft tissue. erefore it is critical to evaluate this
dimension before implant surgery. If the height of the interproximal
bone is lost or the interproximal contact is more incisal, then the
soft tissue will less likely ll the interproximal space. In addition,
contact distances to bone of 7 mm sometimes present a papilla ini-
tially, but after surgical reection the chance this papilla will return
to the original position may be less than 25%.
e higher the gingival scallop, or dierence between the
height of the papilla and the free gingival margin, the higher the
risk for gingival loss after extraction. Likewise, once the tooth is
extracted and an edentulous site is healed, the less likely the surgi-
cal and restorative procedures will be able to restore an ideal soft
tissue contour. In contrast, a atter gingival scallop and an inter-
proximal tissue close to the osseous crest are conducive to minimal
tissue shrinkage and a more ideal outcome. e height of the facial
gingival contour is in the middle of the tooth for the maxillary lat-
eral incisors and the four mandibular anterior teeth; however, it is
slightly to the distal on the central incisors and canines. e height
of the free gingival margins of the two centrals are similar to both
canines. e cervical height of the lateral incisors may be level or
below the centrals and canines but symmetric to each other. It
may be easier to lengthen the cervical contour of the contralateral
incisor when replacing a missing lateral incisor with an implant
Fig. 29.5 Interdental papillae are often highest between the central
incisor, with progressively less height as they proceed distal. The high lip
line during smiling shows the interdistal papillae in more than 85% of the
patients. (Note: The maxillary right lateral incisor is an implant restoration.)
0
5
10
15
20
25
30
35
40
345678910
Frequency of sites
Distance in mm from contact point to crest of bone
Percent
Fig. 29.6 Distance from the interproximal contact to the crest of bone
with natural teeth most often measures 5 mm, 6 mm, or 7 mm.
58
(Tarnow,
D. P., Magner, A. W., & Fletcher, P. (1992). The effect of the distance from
the contact point to the crest of bone on the presence or absence of the
interproximal dental papilla. Journal of periodontology, 63(12), 995-996.)
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Presence/Absence of papilla
3456
Distance in mm from contact point to crest of bone
78910
Percent
Fig. 29.7 When the interproximal contact-to-bone distance is 5 mm
or less, the interdental papilla completely lls (100%) the space between
the teeth. When the contact–bone distance is 6 mm (the most common
measurement), almost 40% of the time a black triangular space occurs
between the teeth from the absence of papilla lling the space. A 7-mm or
greater contact–bone distance nearly always has an incomplete ll of the
interproximal space with the soft tissue. (From Tarnow DP, Magner AW,
Fletcher P. The effect of the distance from the contact point to the crest
of bone on the presence or absence of the interproximal dental papilla.
JPeriodontol. 1992;63(12):995-996.)

710
PART VI Implant Surgery
instead of attempting to lower the gingival contour on the implant
crown when gingiva and bone shrinkage has occurred. e least
desirable gingival contour is seen when one anterior tooth is higher
than the rest. Unfortunately this is a common occurrence with an
implant crown when the bone and/or soft tissue is not augmented
in conjunction with implant insertion or uncovery.
e color and texture of the tissue is also evaluated in the
edentulous tooth site. e attached keratinized gingival tone and
coral-pink color should be similar around the implant abutment
compared with the healthy adjacent teeth. e biotype of the gin-
giva is usually classied as either thick or thin. icker tissue is
more resistant to the shrinkage or recession and more often leads
to the formation of a periodontal pocket after bone loss. in
gingival tissues around the teeth are more prone to shrinkage after
tooth extraction and are more dicult to elevate or augment after
tooth loss. Gingival recession is the most common esthetic com-
plication of thin biotypes after anterior single-tooth extraction
and is also a concern after implant surgery, uncovery, or both.
According to Kois,
19
predictability of the maxillary anterior sin-
gle-tooth implant is ultimately determined by the patients own
presenting anatomy. Favorable conditions include (1) when the
tooth position is more coronal relative to the full gingival margin,
(2) square tooth shapes, (3) at scallop periodontium forms, (4)
thick periodontium biotypes, and (5) high (<3 mm) facial osseous
crest positions of the teeth and midcrestal. Unfavorable patient
anatomy includes (1) aligned or apical preexisting tooth (relative
to the free gingival margin), (2) triangular tooth shapes, (3) high
scallop periodontium form, (4) thin periodontium types, and (5)
low (>4 mm) facial osseous crest positions in relation to adjacent
teeth and the midcrestal area.
Anatomic Challenges
Natural Tooth Size Versus Implant Diameter
e esthetics of a maxillary anterior single crown on a natural
tooth is often one of the most dicult procedures in restorative
dentistry. When an implant is being restored, the challenges are
even greater (Figs. 29.8 and 29.9). When comparing the size and
shape of an implant versus natural tooth, the implant is often
5 mm or less in diameter and round in cross section. A natural
maxillary anterior crown cervix region is approximately 4.5 to 7
mm in mesiodistal cross section and is never completely round. In
fact, the natural central incisor and canine teeth are often larger
in their faciopalatal dimension at the CEJ than in the mesiodistal
dimension. Because the bone is lost rst in the faciopalatal width,
the greater width of implants in this dimension would require
even greater augmentation than presently advocated. As a result,
the cervical esthetics of a single-implant crown must accommo-
date a round-diameter implant and balance hygiene and esthetic
parameters. Additional prosthetic steps and components with
varied emergence proles or customized tooth-colored abutments
are often required to render the illusion of a crown on a natural
abutment.
Compromised Bone Height
e available bone should be closely evaluated because it will greatly
inuence the soft tissue drape, implant size, implant position
(angulation and depth), and ultimately the nal esthetic outcome.
Hard tissue topography is a prerequisite to an optimal, esthetic
implant restoration. erefore a comprehensive cone beam com-
puterized tomography (CBCT) evaluation of the available bone
volume present is mandatory to determine the ideal implant posi-
tion. e osseous midcrestal position of the edentulous site should
be approximately 2 to 3 mm below the facial CEJ or free gingival
margin of the adjacent teeth. e interproximal bone should be
scalloped 3 mm more incisal than the midcrestal position.
e position of the interproximal crest of bone is an impor-
tant anatomic consideration, especially for the development of the
interproximal soft tissue height. Becker and colleagues classied
the range of interproximal bone height above the midfacial scallop
from less than 2.1 mm (at) to scalloped (2.8 mm) to pronounced
scalloped (<4.1 mm).
20
e at anatomy should correspond to
a square-shaped tooth, the scalloped to an ovoid-shaped tooth,
and the pronounced scalloped to a triangular-shaped tooth (Fig.
29.10). However, these relationships do not always exist. When
a at interdental-to-crest dimension is found on triangular teeth,
the interproximal space will usually not be lled with soft tissue
because the dimension of the interproximal contact to the bone
will be greater than 5 mm (Fig. 29.11).
21
Often the osseous crest may be more apical than ideal in both
the implant site and the adjacent tooth roots. Under these con-
ditions, ideal crown contour, soft tissue emergence, and inter-
proximal tissue conditions are less likely (Figs. 29.12 and 29.13).
Instead of the expected FP-1 prosthesis, most likely an FP-2 pros-
thesis will be the end result. Bone and soft tissue changes after
maxillary anterior tooth loss are rather rapid and of considerable
consequence. As a result, many maxillary anterior edentulous sites
Fig. 29.8 Single missing central incisor is often the most challenging
surgical and prosthetic implant to complete. The soft and hard tissues
need to be ideal to obtain an acceptable esthetic result.
Fig. 29.9 Maxillary left central incisor implant crown in position. The soft
tissue drape is established through both surgical and prosthetic methods.

711
CHAPTER 29 Maxillary Anterior Implant Placement
require at least some bone and/or soft tissue modication before,
in conjunction with, and/or at implant uncovery.
Compromised Mesiodistal Space
An adequate mesiodistal space is necessary for an esthetic outcome
of an implant restoration and the interproximal soft tissue health
of the adjacent teeth. A traditional two-piece implant should be a
minimum of 1.5 mm from an adjacent tooth. When the implant
is closer to an adjacent tooth, any bone loss related to the micro-
gap, the biological width, and/or stress may result in loss of bone
around the implant or adjacent tooth. is may compromise
interproximal esthetics and/or sulcular health of the implant and
natural tooth (Fig. 29.14).
22
In addition, when an implant is less
than 1.5 mm from a natural tooth, inadequate room is available
for an ideal emergence prole of the implant restoration.
Compromised Faciopalatal Width
In most cases in which a maxillary anterior single tooth is lost, the
facial plate of bone will be compromised. Studies have shown a
25% decrease in faciopalatal width occurs within the rst year of
tooth loss and rapidly evolves into a 30% to 40% decrease within
3 years. As a result, even an intact alveolus 6 to 8 mm wide is
often inadequate in width after 1 year for a division A root-form
implant in a central incisor position, and after 3 years it almost
never presents adequate available bone for an ideal sized implant.
e bone width loss is primarily from the facial region, because
the labial plate is very thin compared with the palatal plate, and
facial undercuts are often found over the roots of the teeth (Fig.
29.15).
23
Studies have shown the median buccal alveolar thick-
ness in the maxillary anterior region to be; 1 mm apical to alveolar
bone margin = 0.83 mm, midroot = 0.70 mm, and 1 mm from
the tooth apex = 0.88. A bone graft is often necessary to restore the
Fig. 29.10 Triangular tooth form corresponds to the greatest width and
height of interdental papillae and the most incisal interproximal contact
position on the crown.
100
90
80
70
60
50
40
30
20
10
0
3456
Distance in mm from contact point to crest of bone
Percent
Presence/absence of papilla
78
91
0
Fig. 29.11 When natural teeth have an interproximal crown contact to
interseptal bone distance of 5 mm or less, the interdental papilla almost
always lls the interproximal space. When the distance is 6 mm, the inter-
proximal space is not lled with soft tissue almost 40% of the time; at 7
mm the interproximal space is lled with an interproximal papilla 25% of
the time.
Fig. 29.12 Implant position slightly apical to the ideal 3 mm below the
free gingival margin resulting in an FP-2 prosthesis (elongated clinical
crown compared with adjacent teeth).
Fig. 29.13 Implant position signicantly placed apical to the adja-
cent teeth, which will result in remodeling of the crestal bone. Note the
increased crown height space leading to an FP-3 prosthesis (prosthesis
replacing clinical crown and soft tissue with pink porcelain or zirconia).

712
PART VI Implant Surgery
proper anatomy of the ridge and to avoid a compromised implant
position more palatal and apical.
e amount of available bone width (faciopalatal) should be at
least 3.0 mm greater than the implant diameter at implant insertion.
erefore a 3.5-mm implant requires at least 6.5 mm of bone width.
Bone augmentation in width is very predictable. In many instances
it is performed before implant placement; however, in some cases, it
may be performed at the time of implant insertion, especially when
minimal dehiscence of the implant is visible. It should be empha-
sized that the implant diameter measurement is at the crest module
of the implant. Most 3.75-mm-diameter implant bodies are 4.1 mm
at the crest module. In these situations, the mesiodistal limitation is
7.1 mm and the faciolingual width limitation is 7.1 mm.
Selection of the Implant Size
e rst factor that inuences the size of an implant is the mesio-
distal dimension of the missing tooth. e average mesiodistal
dimension of a central incisor is 8.6 mm (male) and 8.1 mm
(female), a lateral incisor is 6.6 mm (male) and 6.1 mm (female),
and a canine is 7.6 mm (male) and 7.2 mm (female). In general,
the implant body should not be as wide as the natural tooth or
clinical crown because the emergence contour and interdental
papillae region cannot be properly established.
e mesiodistal dimensions of the maxillary central incisor
at the cervix (preferably 1 mm below the free gingival margin)
averages 6.4 mm, the lateral incisor dimension is 4.7 mm, and
canine natural teeth at the cervix are 5.6 mm (Table 29.1).
24
However, these dimensions are also too large for an implant. e
bone level on natural teeth is approximately 2 mm below the CEJ;
A B CDE
Fig. 29.15 Bone Resorption in the Maxillary Anterior (A) Before the loss of a maxillary anterior tooth, the
bone around the roots most often is present. (B) Extraction often causes a loss of the thin labial plate of
bone over the root. After extraction, the residual ridge most often is decreased in width (division B). (C)
After 6 months to 1 year, the residual ridge continues to resorb and becomes division B–w. (D) Eventually,
the residual ridge forms a C–w bone volume that is slightly decient in height and less than 2.5 mm in
width. (E) This bone volume often extends almost to the oor of the nose.
1.5 mm 1.5 mm
Fig. 29.14 If bone loss occurs on an implant placed closer than1.5 mm
to a tooth (on the distal), then bone and soft tissue drape will also be lost
on the tooth. As a result, the distance from the interproximal crown con-
tact to the interproximal bone increases, and the risk of soft tissue shrink-
age and loss of interdental papilla increases. When the implant is greater
than1.5 mm from the tooth (on the mesial); bone loss on the implants does
not cause bone loss on the tooth root. The interproximal crown contact
to interproximal bone relationship remains ideal, and the interdental papilla
is maintained.
Maxillary Teeth Dimensions
Type of Tooth
Mesiodistal Crown
(mm)
Mesiodistal Cervix
(mm)
Faciolingual Crown
(mm)
Faciolingual Cervix
(mm)
2 mm Below Cement-
Enamel Junction
Central incisor 8.6 6.4 7.1 6.4 5.5
Lateral incisor 6.6 4.7 6.2 5.8 4.3
Canine 7.6 5.6 8.1 7.6 4.6
TABLE
29.1

713
CHAPTER 29 Maxillary Anterior Implant Placement
the natural tooth dimensions at this bone level are reduced to
5.5 mm for central incisors, 4.3 mm for lateral incisors, and 4.6
mm for canines. erefore, in theory, the latter dimensions most
closely resemble the consummate implant diameter to mimic the
emergence prole of a natural tooth. However, this dimension is
usually too large to adequately restore the soft tissue drape of the
missing anterior tooth.
e second factor that determines the mesiodistal implant
diameter is the necessary distance from an adjacent tooth root.
25
Initial vertical bone loss around an implant during the rst year of
loading is variable and ranges from 0.5 to more than 3.0 mm. e
height of the interseptal (interimplant) bone in part determines
the incidence of presence or absence of the interdental papillae
between the teeth. When the distance from the interseptal bone
to interproximal contact is 5 mm or less, the papilla lls the space.
When the distance is 6 mm, a partial absence of papilla is seen
45% of the time, and at 7 mm the risk of a compromise in the
interproximal space is 75%.
26
erefore the intraseptal bone
height is relative to the maintenance of the interdental papilla and
should be preserved. As a consequence, the implant should be at
least 1.5 mm from the adjacent teeth whenever possible, and the
interseptal bone on the adjacent teeth should be within 5 mm of
the desired interproximal crown contact position.
In summary, two mesiodistal parameters determine the prefer-
able implant size. e suggested width of the single-tooth implant
should correspond to the width of the missing natural tooth,
2 mm below the CEJ. e distance between the roots of the adja-
cent teeth should also be measured. e implant diameter + 3 mm
(1.5 mm on each side) should be equal to or less than the distance
between the adjacent roots, at the crest of the ridge (which is 2
mm below the interproximal CEJ).
e next dimension that determines the width of an anterior
implant is the faciopalatal dimension of bone. e width of bone
should allow at least 1.5 mm on the facial aspect of the implant
so that if a vertical defect forms around the crest module, then
that defect would not become horizontal and change the cervical
contour of the facial gingival (Fig. 29.16). Because of its initial
reduced volume, facial bone tends to be labile, and its resorption
is responsible for most of the compromised long-term esthetic
results in the anterior maxilla. e faciopalatal width dimension
is not as critical on the palatal aspect of the implant because it is
dense cortical bone, more resistant to bone loss, and not within
the esthetic zone. Facial bone grafting at the time of implant inser-
tion is frequently indicated because the bone volume in width is
often compromised (Figs. 29.17 and 29.18).
e width of the implant should mimic the emergence of a nat-
ural tooth and help preserve the bone and health of the adjacent
teeth. e natural intraroot distance of the two central incisors
distance is approximately 2 mm. However, the natural roots of the
central to lateral and lateral to canine are usually less than 1.5 mm
A B
Fig. 29.16 Compromised bone width. (A) Preoperative view is very deceiving and can give a false posi-
tive on the amount of bone present. (B) Reection of the ridge tissue reveals a signicant defect present.
A B
Fig. 29.17 (A) Large ridge defect. (B) To gain adequate width of bone, a symphysis bone graft is com-
pleted.

714
PART VI Implant Surgery
apart and often only 0.5 mm of space exists between them. As a
consequence, the typical size of the single-tooth implant is usually
smaller in diameter than the natural tooth root.
e typical diameters of the implant used to replace the aver-
age-size tooth often results in a 4.0- to 5.2-mm implant for a cen-
tral incisor, a 3.0- to 3.5-mm implant for a lateral incisor, and a
3.7- to 4.2-mm implant for a canine. e dierence in the emer-
gence prole of a 4-mm-diameter implant and a 5-mm-diameter
implant is negligible and often not clinically relevant for an ante-
rior tooth because a 0.5-mm dierence occurs on each side of the
implant. erefore, when in doubt, the clinician should use a
smaller diameter implant. As such, a 4-mm-diameter implant may
often be used in the central-implant position for a single-tooth
replacement. Likewise, a 3.0- to 3.5-mm implant is often used for
a lateral incisor single-tooth restoration (Box 29.1).
Implant Position
e maxillary anterior single-tooth implant should be positioned
precisely in three planes. From a mesiodistal aspect, the implant
most often is placed in the middle of the space, with an equal
amount of interproximal bone toward each adjacent tooth. On
occasion, the central incisor implant is positioned slightly to the
distal of the intratooth space (Fig. 29.19) when the incisive fora-
men is enlarged and encroaches on the ideal placement. When a
central incisor implant is planned and the foramen between the
existing central incisor root and implant site is larger than usual,
the remaining bone may be inadequate for placement.
e nasopalatine foramen may also expand o to one side of the
midline within the bony canal. When the central incisor implant
is placed, the implant may encroach on the canal and result in a
soft tissue interface on the mesiopalatal surface of the implant. As
a precaution, the clinician should reect the palatal tissue when
placing a maxillary central incisor implant and, if necessary, place
the implant in a more distal position (Fig. 29.20). is usually
requires a smaller diameter implant than usual to remain 1.5 mm
or more from the lateral incisor. On occasion, the contents of the
foramen maybe be removed and a bone graft inserted to decrease
the size of the incisive canal.
e midfaciopalatal position of the implant is in the middle to
slightly palatal 0.5 mm of the edentulous ridge of adequate contour.
is approach permits the use of the greatest diameter implant. e
crestal bone should be at least 1.5-2.0 mm wider on the facial aspect
of the implant and 1.0 mm on the palatal aspect. erefore for a
4-mm-diameter implant, a minimum 6.5-mm faciopalatal width of
bone is required for the central or canine position, and 6.0 mm of
bone width is required for a lateral incisor with a 3.5-mm implant.
Bone spreading in conjunction with implant placement or bone
grafting on the facial aspect of the edentulous site may be indicated
when the ridge is less wide than is desirable. e thickness of bone
on the facial aspect of a natural root is usually 0.5-0.7 mm thick in
the anterior region. As a result, if the implant is placed in the center
of the ridge, the implant will be 1 mm or more palatal than the
facial emergence of the adjacent crowns at the free gingival margin.
e implant center is positioned in the faciopalatal center
of the edentulous ridge and the midmesiodistal position. e
implant body angulation from this point is considered next. In
the literature, three faciopalatal angulations of the implant body
are suggested: (1) a facial angulation so that emergence of the nal
crown will be similar to adjacent teeth, (2) under the incisal edge
of the nal restoration, and (3) within the cingulum position of
the implant crown (Fig. 29.21).
Facial Implant Body Angulation
Researchers often theorize that a maxillary anterior implant body
angulation should be positioned at the facial emergence of the nal
crown. e facial implant position is predicated on the concept that
the facial emergence of the implant crown at the cervical should be
in the same position as a natural tooth. At rst, this makes some
sense. However, the crown of a natural tooth has two planes, and its
incisal edge is palatal to the facial emergence of the natural tooth by
12 to 15 degrees (Fig. 29.22). is is why anterior crown prepara-
tions are in two or three planes. e implant body is more palatal
than a natural root, so 1.5 mm of bone exists facially. In addition,
because the implant is narrower in diameter than the faciopalatal
root dimension, when the implant body is oriented as a natural
tooth and has a facial emergence, a straight abutment is not wide
enough to permit the two or three plane reduction to bring the inci-
sal edge of the preparation more palatal. As a result, the incisal edge
of the preparation remains too facial. erefore when the implant is
angled to the facial emergence of a tooth, an angled abutment of 15
degrees must be used to bring the incisal edge more palatal. Most
two-piece angled abutments have a design aw that compromises
facial cervical esthetics. e metal ange facial to the abutment
AB
Fig. 29.18 (A) Compromised ridge with signicant deciency in width. (B) Guided bone regeneration
required to obtain sufcient width and height for implant placement.
Central incisor: 4.0–5.2 mm
Lateral incisor: 3.0–3.5 mm
Canine: 3.7–4.2 mm
BOX
29.1
Ideal Average Implant Diameter

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70629Maxillary Anterior Implant PlacementRANDOLPH R. RESNIK AND CARL E. MISCH*Maxillary Anterior Implant PlacementContrary to missing a posterior tooth, most patients have an emotional response regarding a maxillary anterior missing tooth. Because the premaxillary teeth are directly within the smile line, no question exists regarding the need to replace the tooth, and nancial considerations are usually less important. When poste-rior teeth are extracted, little resistance to the preparation of adja-cent teeth may be given to the dentist. However, when anterior, normal-looking teeth must be prepared to serve as xed partial denture (FPD) abutments, the patient is more anxious and often looks for an alternative. In the patient’s perspective, anterior FPD prostheses are never as esthetic as natural teeth. is in part is because they are able to distinguish between the esthetics of a nat-ural tooth versus a porcelain/zirconia restoration.erefore the profession and patients are gravitating to implant replacement instead of conventional prosthetics. Single-tooth implants are now one of the most common implant procedures performed in the United States. In the nonesthetic posterior region, the single-tooth implant is one of the simplest procedures in implant surgery and prosthetics. However, it should be noted, the maxillary anterior single-tooth replacement is often the most dicult procedure in all of implant dentistry.e highly esthetic zone of the premaxilla often requires both hard (bone and teeth) and soft tissue restoration. e soft tissue drape is usually the most dicult aspect of treatment to develop and maintain. As a consequence, maxillary anterior single-tooth replacement is often a signicant challenge, regardless of the expe-rience and skill of the clinician.Maxillary Anterior Implant StudiesIn general, the single-tooth implant has the highest success rate compared with any other treatment option to replace missing teeth with an implant restoration (e.g., short-span FPD, full-arch FPD, single-tooth implant).1-4 Misch and colleagues reported on 276 anterior maxillary single implants used to restore missing teeth from agenesis. In 255 adolescent patients, the implants were monitored for a range of 2 to 16 years, with a 98.6% implant and crown survival rate.5 In the same year, Wennstrom and colleagues reported on a 5-year prospective study with 45 single-tooth implants, with a 97.7% implant survival rate with minimal bone loss.6 In 2006, Zarone and colleagues reported on lateral maxil-lary agenesis replacement with 34 implants, with a 97% survival rate at 39 months.7 A review of the literature by Goodacre and colleagues found that single-tooth implant studies had the highest survival rate of any prosthesis type and averaged 97%.8 erefore the maxillary anterior implant has been well researched and most studies show a very high success rate.More recently, a trend toward single-stage and immediate-placement implants has emerged, appearing especially attractive in the maxillary anterior region. is is preferable because the soft tissue drape is easier to retain, and with this type of treat-ment shorter treatment time is advantageous. Kemppainen and colleagues in a prospective study of 102 single-tooth implants in the anterior maxilla, reported a 99% success rate using one- and two-stage implant protocols.9 Other studies have recommended one-stage and immediate load with overwhelming success.10,11 Maxillary Anterior Teeth Evaluatione maxillary anterior implant is successful only if the nal resto-ration it supports is fully supported functionally and esthetically with the adjacent dentition. e exponential growth of the eld of implant dentistry has been paralleled by exciting new advance-ments in esthetic dentistry and plastic regenerative surgery. is growth has made the profession realize that the restoration of the peri-implant soft and hard tissue to an optimal architecture is the key to a successful implant restoration. It is no longer acceptable practice to only achieve osteointegration with an implant. e implant restoration complex in the esthetic zone should ideally be achieved in a context that respects all biological tissues (Fig. 29.1).When the goal for a maxillary incisor single-tooth replacement is to obtain an ideal result, the clinician should rst evaluate not only the edentulous site but also the remaining anterior teeth. Because only one tooth is missing, the adjacent teeth most often dictate its length, contour, shape, and position. If this is not sat-isfactory, then a potential modication may need to be integrated into the overall treatment plan.Parameters for a healthy esthetic anterior restoration have been established. e following guidelines have been proposed by esthetic and cosmetic dentistry colleagues. ese parameters *Deceased. 707CHAPTER 29 Maxillary Anterior Implant Placementplay a determinant role in the nal result and should not be over-looked. e patient must be educated about their present condi-tion before the onset of treatment, and the starting point should be documented. e patient, once fully informed of the existing discrepancies and their potential negative eect on the envisioned result, may decide to address and correct the existing problems of the adjacent teeth or simply elect to accept the compromise. Correction may be as simple as bleaching the remaining teeth or as complex as full esthetic rehabilitation with crown lengthen-ing, soft tissue plastic surgery, veneers or crowns, and orthodontic therapy (or a combination of these procedures).Maxillary Tooth Sizee two maxillary central incisors should appear symmetric and of similar size, most importantly when the patient has a high smile line. is is most critical to evaluate when the missing tooth is one central incisor (Fig. 29.2). Outline asymmetry is visu-ally acceptable the more distal from the midline the eye travels. When one maxillary tooth is missing, the remaining space may be compromised from drifting of the adjacent teeth. Orthodontic intervention may be indicated when the missing tooth is a cen-tral incisor with a mesiodistal space less or more than the size of the corresponding central incisor. e other option is to modify the existing central incisor with a veneer or composite to make it similar in size and shape to the missing tooth restoration. is has the advantage of lowering the mesial interproximal contact and making the two centrals more square shaped, which decreases the height requirement of the papilla. e shades of the two centrals is easier to match when made at the same time in the laboratory. To understand ideal tooth size, the clinician should have a clear understanding of the normal and average tooth dimensions.Central Incisor. e average clinical crown length of the maxil-lary central incisor is 10.2 mm for a male patient and 9.4 mm for a female patient.12 In some cases, surgical crown lengthening and longer anterior teeth may be indicated to reduce gingival exposure during a high-smile lip position. Because the clinical crown height of an implant-supported central incisor is often longer than the adjacent tooth, an esthetic crown lengthening on the natural tooth may be used to align the gingival margins. When an implant crown is longer than the corresponding natural tooth, a crown-length-ening procedure may be more predictable on the natural tooth than attempting to augment the implant crown with soft tissue. However, the clinical crowns of natural teeth are rarely more than 12 mm high. e width of the average maxillary central is 8.6 mm for a male patient and 8.1 mm for a female patient. Although male teeth are usually slightly longer and wider, the length to width ratio is similar to female teeth, (0.85 for male patients and 0.86 for female patients). A ratio range of 0.70 to 0.86 has been reported to be acceptable for the central incisors when they are similar. When the anterior teeth are made longer and both centrals have the same width, an acceptable result may be obtained. Lateral Incisor. e average clinical crown length of the maxil-lary lateral incisor is 8.7 mm for a male patient and 7.8 mm for a female patient. erefore the average lateral incisor is almost 1.5 mm shorter than the central incisor (at both the gingival region and the incisal edge). Gingival margins of the maxillary lateral inci-sors may be similar to centrals and canines, but they should not be higher than the neighboring teeth. erefore an implant crown on the lateral incisor should not be longer than the central or canine. e average width of a lateral incisor is 6.6 mm for a male patient and 6.1 mm for a female patient, but this is more variable than for any other anterior tooth. e length to width ratio is slightly greater for a female patient (0.79, compared with the male patient ratio of 0.76). A lateral incisor space may be slightly narrower than the other natural tooth; however, when replacing the lateral incisor, it may be preferable to perform a slight mesial stripping of the adja-cent canine to duplicate and make symmetric the lateral incisors. Canine. e average male canine clinical crown length is 10.1 mm and width is 7.6 mm, with a ratio of 0.77. e canine is usu-ally the same height as the central but 1 mm narrower. Usually the lateral incisor is 1 mm narrower than the cuspid. e female canine height averages 8.9 mm (0.5 mm shorter than the central) and 7.2 mm in width (1 mm narrower), with a ratio of 0.81. As a general rule, regardless of sex, the central incisor is 2 mm wider than the lat-eral incisor and 1 mm wider than the canine. However, on the hori-zontal plane, the canine is 1 to 2 mm shorter than the central incisor and corresponds to the curvature of the lower lip during smiling. Tooth Shaperee basic shapes of maxillary anterior teeth exist: (1) square, (2) ovoid, and (3) triangular. e tooth shape will directly inuence the interproximal contact area and the gingival embrasure. e • Fig. 29.1 Maxillary anterior implants that may be functional; however, in some situations (i.e., high smile line) they may not be esthetically pleasing to patients because of the addition of pink porcelain between the lateral and central incisor.• Fig. 29.2 Patient’s left maxillary central incisor was replaced with an implant and crown. The tooth is wider than the right central incisor. Ortho-dontics could have reduced the horizontal overjet of the lateral and central incisors and resulted in more symmetric teeth. A second option is a veneer on the right central incisor to correct the rotation and make the natural tooth more symmetric to the implant crown. 708PART VI Implant Surgerysquare tooth shape is the most favorable to obtain an ideal soft tissue drape and papillae around the crown because the interproxi-mal contact is further apical and more tooth structure will ll the interproximal region. In contrast, a triangular tooth shape has a more incisal interproximal contact, a steeper gingival scallop, and is farther from the interproximal bone (Fig. 29.3). As a result, a space often exists between the interproximal contact and the inter-dental papilla of the remaining teeth. is is especially noteworthy to observe at the initial examination. When the soft tissue lls the interproximal space of the remaining anterior teeth that have a triangular shape, the tissues may be very liable and easily disap-pear during the healing phases after implant surgery. Care should be taken if the adjacent soft tissue requires reection for a bone graft before the implant insertion. e ideal restoration of the soft tissue with a triangular-shaped tooth is less predictable.e cervical embrasure of the adjacent teeth to the edentulous site should be particularly evaluated. A triangular tooth is narrow at the cervical embrasure, and the base of the interproximal tissue is wide. In addition, the adjacent tooth contact is often higher o the tissue, with an increased risk of a black triangular space. When such a condition is present on the adjacent teeth of the missing tooth, it is likely that the interdental papillae region will also be compromised on the implant crown. e tooth shape also aects the topography of the underlying hard tissues. e roots of triangular tooth shapes are positioned farther apart; therefore they have thicker facial and interproximal bone. is may decrease the amount of crestal bone loss after an extraction. In addition, the prognosis for an immediate implant insertion is more favorable in these situations because the bone defect is smaller in diameter and the interproximal bone more likely to provide the recommended 1.5 mm or more of interproxi-mal bone from the adjacent tooth. e square-shaped tooth is more likely to have less interproximal bone between the roots. erefore it presents a greater risk of crestal or interproximal bone loss with an immediate implant insertion, making it less favorable for immedi-ate implant insertion after extraction. Soft Tissue Drapee height of the maxillary lip when smiling (high lip line) is one of the most important criterion to evaluate when observing the cervical region of the maxillary anterior teeth. Its position is usu-ally related to age, with older men showing the least amount of teeth and soft tissue and younger female patients displaying the most. Some patients (15% of male patients and 6% of female patients) show only the incisal half of the anterior teeth when they smile.13 ose patients should be identied and it should be explained in detail that an ideal soft tissue result in the gingival region is not mandatory. Clinical results in emergence contours, interdental papilla presence, and even shade and contour of the crown are much less demanding. erefore the additional surgical intervention and cost may not be necessary when these patients are willing to accept a slight compromise in ideal esthetics (Fig. 29.4).Ideally the height of the maxillary lip should rest at the junc-tion of the free gingival margin on the facial aspect of the maxil-lary centrals and canine teeth.14,15 us the interdental papillae are visible, but little gingival display is seen over the clinical crowns. Almost 70% of patients have this ideal smile position. A “gummy” smile is dened as showing more than 2 mm of soft tissue above the clinical maxillary crowns and is more acceptable in the female patient. It may occur in more than 14% of the female population and 7% of the male population. e higher the high lip line, the more ideal the esthetic requirements are for the remaining teeth and the single-tooth replacement. erefore the existing maxillary anterior teeth condition is closely scrutinized when a high lip line exists and ideal results are desired.e soft tissue drape of the remaining teeth should be evalu-ated, especially if exposed during the high lip position of smiling. Under ideal conditions, soft tissue completely lls the interproxi-mal space, with no dark triangles from the absence of light within the oral cavity. e interproximal contact between the maxillary central incisors should begin in the incisal third of the teeth and • Fig. 29.3 Triangular tooth shape has the steepest gingival scallop, and the interproximal bone is farthest from the tip of the papilla. After an extrac-tion, shrinkage of the tissue makes the soft tissue drape in this tooth shape the most difcult to restore.AB• Fig. 29.4 (A) The maxillary left central incisor was restored with an implant restoration. The patient desired a soft tissue graft to cover the implant crest module. (B) The high lip position during smiling did not dis-play the cervical region of the patient’s central incisors. Although this is not an ideal result, additional surgeries would not improve the crown’s appearance within the esthetic zone, and the soft tissue pocket created may increase the risk of peri-implantitis. 709CHAPTER 29 Maxillary Anterior Implant Placementcontinue to the height of the central interdental papilla. In a healthy patient, very little to no space is seen between the papillae and interproximal contact. According to Kois, the distance from the facial free gingival margin to the height of the central midin-terproximal papilla is usually 4 to 5 mm; therefore the interden-tal papilla height is approximately 40% to 50% of the exposed tooth length.16 Interproximal contacts at the incisal position start progressively more gingivally from central to canine. e greatest papilla height is often between the centrals, slightly lower between the centrals and laterals, and even lower between laterals and canines (Fig. 29.5).However, the papilla height is often similar between the cen-trals and from the centrals to the laterals. Under ideal conditions the osseous scallop of bone in the maxillary anterior region begins 2 mm below the cement-enamel junction (CEJ) midfacial to a point 3 mm more incisal in the interproximal region. e soft tis-sue follows this osseous scallop. A soft tissue biological dimension of approximately 3 mm in height above the bone is present at the midfacial position (1 mm above the CEJ) and 3 to 5 mm above the interproximal bone. erefore if the interproximal contact is within 3 to 5 mm of the interproximal bone, then the interdental papilla will most often completely ll the space. Tarnow and col-leagues17 and Norland and Tarnow18 measured the distance from the bottom of the interproximal contact to the vertical height of interproximal bone on natural teeth and observed how frequently the interproximal space would be completely lled by soft tissue. e distances ranged from 3 to 10 mm, with 88% of the contacts to the bone at 5 mm, 6 mm, or 7 mm; the most common mea-surement was 6 mm (40%), followed by 5 mm (25%), and then 7 mm (22%) (Fig. 29.6).When the contact point to bone was 3 to 5 mm, the papilla almost always lled the space. When the contact was 6 mm, an absence of papilla was noted almost 45% of the time; at a 7-mm distance the papilla did not ll the space 75% of the time (Fig. 29.7). In other words, a dierence of 1 to 2 mm from the interprox-imal contact to the interseptal bone is very signicant in relation to the interproximal soft tissue. erefore it is critical to evaluate this dimension before implant surgery. If the height of the interproximal bone is lost or the interproximal contact is more incisal, then the soft tissue will less likely ll the interproximal space. In addition, contact distances to bone of 7 mm sometimes present a papilla ini-tially, but after surgical reection the chance this papilla will return to the original position may be less than 25%.e higher the gingival scallop, or dierence between the height of the papilla and the free gingival margin, the higher the risk for gingival loss after extraction. Likewise, once the tooth is extracted and an edentulous site is healed, the less likely the surgi-cal and restorative procedures will be able to restore an ideal soft tissue contour. In contrast, a atter gingival scallop and an inter-proximal tissue close to the osseous crest are conducive to minimal tissue shrinkage and a more ideal outcome. e height of the facial gingival contour is in the middle of the tooth for the maxillary lat-eral incisors and the four mandibular anterior teeth; however, it is slightly to the distal on the central incisors and canines. e height of the free gingival margins of the two centrals are similar to both canines. e cervical height of the lateral incisors may be level or below the centrals and canines but symmetric to each other. It may be easier to lengthen the cervical contour of the contralateral incisor when replacing a missing lateral incisor with an implant • Fig. 29.5 Interdental papillae are often highest between the central incisor, with progressively less height as they proceed distal. The high lip line during smiling shows the interdistal papillae in more than 85% of the patients. (Note: The maxillary right lateral incisor is an implant restoration.)0510152025303540345678910Frequency of sitesDistance in mm from contact point to crest of bonePercent• Fig. 29.6 Distance from the interproximal contact to the crest of bone with natural teeth most often measures 5 mm, 6 mm, or 7 mm.58 (Tarnow, D. P., Magner, A. W., & Fletcher, P. (1992). The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. Journal of periodontology, 63(12), 995-996.)0.010.020.030.040.050.060.070.080.090.0100.0Presence/Absence of papilla3456Distance in mm from contact point to crest of bone78910Percent• Fig. 29.7 When the interproximal contact-to-bone distance is 5 mm or less, the interdental papilla completely lls (100%) the space between the teeth. When the contact–bone distance is 6 mm (the most common measurement), almost 40% of the time a black triangular space occurs between the teeth from the absence of papilla lling the space. A 7-mm or greater contact–bone distance nearly always has an incomplete ll of the interproximal space with the soft tissue. (From Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. JPeriodontol. 1992;63(12):995-996.) 710PART VI Implant Surgeryinstead of attempting to lower the gingival contour on the implant crown when gingiva and bone shrinkage has occurred. e least desirable gingival contour is seen when one anterior tooth is higher than the rest. Unfortunately this is a common occurrence with an implant crown when the bone and/or soft tissue is not augmented in conjunction with implant insertion or uncovery.e color and texture of the tissue is also evaluated in the edentulous tooth site. e attached keratinized gingival tone and coral-pink color should be similar around the implant abutment compared with the healthy adjacent teeth. e biotype of the gin-giva is usually classied as either thick or thin. icker tissue is more resistant to the shrinkage or recession and more often leads to the formation of a periodontal pocket after bone loss. in gingival tissues around the teeth are more prone to shrinkage after tooth extraction and are more dicult to elevate or augment after tooth loss. Gingival recession is the most common esthetic com-plication of thin biotypes after anterior single-tooth extraction and is also a concern after implant surgery, uncovery, or both. According to Kois,19 predictability of the maxillary anterior sin-gle-tooth implant is ultimately determined by the patient’s own presenting anatomy. Favorable conditions include (1) when the tooth position is more coronal relative to the full gingival margin, (2) square tooth shapes, (3) at scallop periodontium forms, (4) thick periodontium biotypes, and (5) high (<3 mm) facial osseous crest positions of the teeth and midcrestal. Unfavorable patient anatomy includes (1) aligned or apical preexisting tooth (relative to the free gingival margin), (2) triangular tooth shapes, (3) high scallop periodontium form, (4) thin periodontium types, and (5) low (>4 mm) facial osseous crest positions in relation to adjacent teeth and the midcrestal area. Anatomic ChallengesNatural Tooth Size Versus Implant Diametere esthetics of a maxillary anterior single crown on a natural tooth is often one of the most dicult procedures in restorative dentistry. When an implant is being restored, the challenges are even greater (Figs. 29.8 and 29.9). When comparing the size and shape of an implant versus natural tooth, the implant is often 5 mm or less in diameter and round in cross section. A natural maxillary anterior crown cervix region is approximately 4.5 to 7 mm in mesiodistal cross section and is never completely round. In fact, the natural central incisor and canine teeth are often larger in their faciopalatal dimension at the CEJ than in the mesiodistal dimension. Because the bone is lost rst in the faciopalatal width, the greater width of implants in this dimension would require even greater augmentation than presently advocated. As a result, the cervical esthetics of a single-implant crown must accommo-date a round-diameter implant and balance hygiene and esthetic parameters. Additional prosthetic steps and components with varied emergence proles or customized tooth-colored abutments are often required to render the illusion of a crown on a natural abutment. Compromised Bone Heighte available bone should be closely evaluated because it will greatly inuence the soft tissue drape, implant size, implant position (angulation and depth), and ultimately the nal esthetic outcome. Hard tissue topography is a prerequisite to an optimal, esthetic implant restoration. erefore a comprehensive cone beam com-puterized tomography (CBCT) evaluation of the available bone volume present is mandatory to determine the ideal implant posi-tion. e osseous midcrestal position of the edentulous site should be approximately 2 to 3 mm below the facial CEJ or free gingival margin of the adjacent teeth. e interproximal bone should be scalloped 3 mm more incisal than the midcrestal position.e position of the interproximal crest of bone is an impor-tant anatomic consideration, especially for the development of the interproximal soft tissue height. Becker and colleagues classied the range of interproximal bone height above the midfacial scallop from less than 2.1 mm (at) to scalloped (2.8 mm) to pronounced scalloped (<4.1 mm).20 e at anatomy should correspond to a square-shaped tooth, the scalloped to an ovoid-shaped tooth, and the pronounced scalloped to a triangular-shaped tooth (Fig. 29.10). However, these relationships do not always exist. When a at interdental-to-crest dimension is found on triangular teeth, the interproximal space will usually not be lled with soft tissue because the dimension of the interproximal contact to the bone will be greater than 5 mm (Fig. 29.11).21Often the osseous crest may be more apical than ideal in both the implant site and the adjacent tooth roots. Under these con-ditions, ideal crown contour, soft tissue emergence, and inter-proximal tissue conditions are less likely (Figs. 29.12 and 29.13). Instead of the expected FP-1 prosthesis, most likely an FP-2 pros-thesis will be the end result. Bone and soft tissue changes after maxillary anterior tooth loss are rather rapid and of considerable consequence. As a result, many maxillary anterior edentulous sites • Fig. 29.8 Single missing central incisor is often the most challenging surgical and prosthetic implant to complete. The soft and hard tissues need to be ideal to obtain an acceptable esthetic result.• Fig. 29.9 Maxillary left central incisor implant crown in position. The soft tissue drape is established through both surgical and prosthetic methods. 711CHAPTER 29 Maxillary Anterior Implant Placementrequire at least some bone and/or soft tissue modication before, in conjunction with, and/or at implant uncovery. Compromised Mesiodistal SpaceAn adequate mesiodistal space is necessary for an esthetic outcome of an implant restoration and the interproximal soft tissue health of the adjacent teeth. A traditional two-piece implant should be a minimum of 1.5 mm from an adjacent tooth. When the implant is closer to an adjacent tooth, any bone loss related to the micro-gap, the biological width, and/or stress may result in loss of bone around the implant or adjacent tooth. is may compromise interproximal esthetics and/or sulcular health of the implant and natural tooth (Fig. 29.14).22 In addition, when an implant is less than 1.5 mm from a natural tooth, inadequate room is available for an ideal emergence prole of the implant restoration. Compromised Faciopalatal WidthIn most cases in which a maxillary anterior single tooth is lost, the facial plate of bone will be compromised. Studies have shown a 25% decrease in faciopalatal width occurs within the rst year of tooth loss and rapidly evolves into a 30% to 40% decrease within 3 years. As a result, even an intact alveolus 6 to 8 mm wide is often inadequate in width after 1 year for a division A root-form implant in a central incisor position, and after 3 years it almost never presents adequate available bone for an ideal sized implant. e bone width loss is primarily from the facial region, because the labial plate is very thin compared with the palatal plate, and facial undercuts are often found over the roots of the teeth (Fig. 29.15).23 Studies have shown the median buccal alveolar thick-ness in the maxillary anterior region to be; 1 mm apical to alveolar bone margin = 0.83 mm, midroot = 0.70 mm, and 1 mm from the tooth apex = 0.88. A bone graft is often necessary to restore the • Fig. 29.10 Triangular tooth form corresponds to the greatest width and height of interdental papillae and the most incisal interproximal contact position on the crown.10090807060504030201003456Distance in mm from contact point to crest of bonePercentPresence/absence of papilla78910• Fig. 29.11 When natural teeth have an interproximal crown contact to interseptal bone distance of 5 mm or less, the interdental papilla almost always lls the interproximal space. When the distance is 6 mm, the inter-proximal space is not lled with soft tissue almost 40% of the time; at 7 mm the interproximal space is lled with an interproximal papilla 25% of the time.• Fig. 29.12 Implant position slightly apical to the ideal 3 mm below the free gingival margin resulting in an FP-2 prosthesis (elongated clinical crown compared with adjacent teeth).• Fig. 29.13 Implant position signicantly placed apical to the adja-cent teeth, which will result in remodeling of the crestal bone. Note the increased crown height space leading to an FP-3 prosthesis (prosthesis replacing clinical crown and soft tissue with pink porcelain or zirconia). 712PART VI Implant Surgeryproper anatomy of the ridge and to avoid a compromised implant position more palatal and apical.e amount of available bone width (faciopalatal) should be at least 3.0 mm greater than the implant diameter at implant insertion. erefore a 3.5-mm implant requires at least 6.5 mm of bone width. Bone augmentation in width is very predictable. In many instances it is performed before implant placement; however, in some cases, it may be performed at the time of implant insertion, especially when minimal dehiscence of the implant is visible. It should be empha-sized that the implant diameter measurement is at the crest module of the implant. Most 3.75-mm-diameter implant bodies are 4.1 mm at the crest module. In these situations, the mesiodistal limitation is 7.1 mm and the faciolingual width limitation is 7.1 mm. Selection of the Implant Sizee rst factor that inuences the size of an implant is the mesio-distal dimension of the missing tooth. e average mesiodistal dimension of a central incisor is 8.6 mm (male) and 8.1 mm (female), a lateral incisor is 6.6 mm (male) and 6.1 mm (female), and a canine is 7.6 mm (male) and 7.2 mm (female). In general, the implant body should not be as wide as the natural tooth or clinical crown because the emergence contour and interdental papillae region cannot be properly established.e mesiodistal dimensions of the maxillary central incisor at the cervix (preferably 1 mm below the free gingival margin) averages 6.4 mm, the lateral incisor dimension is 4.7 mm, and canine natural teeth at the cervix are 5.6 mm (Table 29.1).24 However, these dimensions are also too large for an implant. e bone level on natural teeth is approximately 2 mm below the CEJ; A B CDE• Fig. 29.15 Bone Resorption in the Maxillary Anterior (A) Before the loss of a maxillary anterior tooth, the bone around the roots most often is present. (B) Extraction often causes a loss of the thin labial plate of bone over the root. After extraction, the residual ridge most often is decreased in width (division B). (C) After 6 months to 1 year, the residual ridge continues to resorb and becomes division B–w. (D) Eventually, the residual ridge forms a C–w bone volume that is slightly decient in height and less than 2.5 mm in width. (E) This bone volume often extends almost to the oor of the nose.1.5 mm 1.5 mm• Fig. 29.14 If bone loss occurs on an implant placed closer than1.5 mm to a tooth (on the distal), then bone and soft tissue drape will also be lost on the tooth. As a result, the distance from the interproximal crown con-tact to the interproximal bone increases, and the risk of soft tissue shrink-age and loss of interdental papilla increases. When the implant is greater than1.5 mm from the tooth (on the mesial); bone loss on the implants does not cause bone loss on the tooth root. The interproximal crown contact to interproximal bone relationship remains ideal, and the interdental papilla is maintained. Maxillary Teeth DimensionsType of ToothMesiodistal Crown (mm)Mesiodistal Cervix (mm)Faciolingual Crown (mm)Faciolingual Cervix (mm)2 mm Below Cement-Enamel JunctionCentral incisor 8.6 6.4 7.1 6.4 5.5Lateral incisor 6.6 4.7 6.2 5.8 4.3Canine 7.6 5.6 8.1 7.6 4.6 TABLE 29.1 713CHAPTER 29 Maxillary Anterior Implant Placementthe natural tooth dimensions at this bone level are reduced to 5.5 mm for central incisors, 4.3 mm for lateral incisors, and 4.6 mm for canines. erefore, in theory, the latter dimensions most closely resemble the consummate implant diameter to mimic the emergence prole of a natural tooth. However, this dimension is usually too large to adequately restore the soft tissue drape of the missing anterior tooth.e second factor that determines the mesiodistal implant diameter is the necessary distance from an adjacent tooth root.25 Initial vertical bone loss around an implant during the rst year of loading is variable and ranges from 0.5 to more than 3.0 mm. e height of the interseptal (interimplant) bone in part determines the incidence of presence or absence of the interdental papillae between the teeth. When the distance from the interseptal bone to interproximal contact is 5 mm or less, the papilla lls the space. When the distance is 6 mm, a partial absence of papilla is seen 45% of the time, and at 7 mm the risk of a compromise in the interproximal space is 75%.26 erefore the intraseptal bone height is relative to the maintenance of the interdental papilla and should be preserved. As a consequence, the implant should be at least 1.5 mm from the adjacent teeth whenever possible, and the interseptal bone on the adjacent teeth should be within 5 mm of the desired interproximal crown contact position.In summary, two mesiodistal parameters determine the prefer-able implant size. e suggested width of the single-tooth implant should correspond to the width of the missing natural tooth, 2 mm below the CEJ. e distance between the roots of the adja-cent teeth should also be measured. e implant diameter + 3 mm (1.5 mm on each side) should be equal to or less than the distance between the adjacent roots, at the crest of the ridge (which is 2 mm below the interproximal CEJ).e next dimension that determines the width of an anterior implant is the faciopalatal dimension of bone. e width of bone should allow at least 1.5 mm on the facial aspect of the implant so that if a vertical defect forms around the crest module, then that defect would not become horizontal and change the cervical contour of the facial gingival (Fig. 29.16). Because of its initial reduced volume, facial bone tends to be labile, and its resorption is responsible for most of the compromised long-term esthetic results in the anterior maxilla. e faciopalatal width dimension is not as critical on the palatal aspect of the implant because it is dense cortical bone, more resistant to bone loss, and not within the esthetic zone. Facial bone grafting at the time of implant inser-tion is frequently indicated because the bone volume in width is often compromised (Figs. 29.17 and 29.18).e width of the implant should mimic the emergence of a nat-ural tooth and help preserve the bone and health of the adjacent teeth. e natural intraroot distance of the two central incisors distance is approximately 2 mm. However, the natural roots of the central to lateral and lateral to canine are usually less than 1.5 mm A B• Fig. 29.16 Compromised bone width. (A) Preoperative view is very deceiving and can give a false posi-tive on the amount of bone present. (B) Reection of the ridge tissue reveals a signicant defect present.A B• Fig. 29.17 (A) Large ridge defect. (B) To gain adequate width of bone, a symphysis bone graft is com-pleted. 714PART VI Implant Surgeryapart and often only 0.5 mm of space exists between them. As a consequence, the typical size of the single-tooth implant is usually smaller in diameter than the natural tooth root.e typical diameters of the implant used to replace the aver-age-size tooth often results in a 4.0- to 5.2-mm implant for a cen-tral incisor, a 3.0- to 3.5-mm implant for a lateral incisor, and a 3.7- to 4.2-mm implant for a canine. e dierence in the emer-gence prole of a 4-mm-diameter implant and a 5-mm-diameter implant is negligible and often not clinically relevant for an ante-rior tooth because a 0.5-mm dierence occurs on each side of the implant. erefore, when in doubt, the clinician should use a smaller diameter implant. As such, a 4-mm-diameter implant may often be used in the central-implant position for a single-tooth replacement. Likewise, a 3.0- to 3.5-mm implant is often used for a lateral incisor single-tooth restoration (Box 29.1). Implant Positione maxillary anterior single-tooth implant should be positioned precisely in three planes. From a mesiodistal aspect, the implant most often is placed in the middle of the space, with an equal amount of interproximal bone toward each adjacent tooth. On occasion, the central incisor implant is positioned slightly to the distal of the intratooth space (Fig. 29.19) when the incisive fora-men is enlarged and encroaches on the ideal placement. When a central incisor implant is planned and the foramen between the existing central incisor root and implant site is larger than usual, the remaining bone may be inadequate for placement.e nasopalatine foramen may also expand o to one side of the midline within the bony canal. When the central incisor implant is placed, the implant may encroach on the canal and result in a soft tissue interface on the mesiopalatal surface of the implant. As a precaution, the clinician should reect the palatal tissue when placing a maxillary central incisor implant and, if necessary, place the implant in a more distal position (Fig. 29.20). is usually requires a smaller diameter implant than usual to remain 1.5 mm or more from the lateral incisor. On occasion, the contents of the foramen maybe be removed and a bone graft inserted to decrease the size of the incisive canal.e midfaciopalatal position of the implant is in the middle to slightly palatal 0.5 mm of the edentulous ridge of adequate contour. is approach permits the use of the greatest diameter implant. e crestal bone should be at least 1.5-2.0 mm wider on the facial aspect of the implant and 1.0 mm on the palatal aspect. erefore for a 4-mm-diameter implant, a minimum 6.5-mm faciopalatal width of bone is required for the central or canine position, and 6.0 mm of bone width is required for a lateral incisor with a 3.5-mm implant. Bone spreading in conjunction with implant placement or bone grafting on the facial aspect of the edentulous site may be indicated when the ridge is less wide than is desirable. e thickness of bone on the facial aspect of a natural root is usually 0.5-0.7 mm thick in the anterior region. As a result, if the implant is placed in the center of the ridge, the implant will be 1 mm or more palatal than the facial emergence of the adjacent crowns at the free gingival margin.e implant center is positioned in the faciopalatal center of the edentulous ridge and the midmesiodistal position. e implant body angulation from this point is considered next. In the literature, three faciopalatal angulations of the implant body are suggested: (1) a facial angulation so that emergence of the nal crown will be similar to adjacent teeth, (2) under the incisal edge of the nal restoration, and (3) within the cingulum position of the implant crown (Fig. 29.21). Facial Implant Body AngulationResearchers often theorize that a maxillary anterior implant body angulation should be positioned at the facial emergence of the nal crown. e facial implant position is predicated on the concept that the facial emergence of the implant crown at the cervical should be in the same position as a natural tooth. At rst, this makes some sense. However, the crown of a natural tooth has two planes, and its incisal edge is palatal to the facial emergence of the natural tooth by 12 to 15 degrees (Fig. 29.22). is is why anterior crown prepara-tions are in two or three planes. e implant body is more palatal than a natural root, so 1.5 mm of bone exists facially. In addition, because the implant is narrower in diameter than the faciopalatal root dimension, when the implant body is oriented as a natural tooth and has a facial emergence, a straight abutment is not wide enough to permit the two or three plane reduction to bring the inci-sal edge of the preparation more palatal. As a result, the incisal edge of the preparation remains too facial. erefore when the implant is angled to the facial emergence of a tooth, an angled abutment of 15 degrees must be used to bring the incisal edge more palatal. Most two-piece angled abutments have a design aw that compromises facial cervical esthetics. e metal ange facial to the abutment AB• Fig. 29.18 (A) Compromised ridge with signicant deciency in width. (B) Guided bone regeneration required to obtain sufcient width and height for implant placement.Central incisor: 4.0–5.2 mmLateral incisor: 3.0–3.5 mmCanine: 3.7–4.2 mm • BOX 29.1 Ideal Average Implant Diameter 715CHAPTER 29 Maxillary Anterior Implant Placementscrew is thinner than a straight abutment and may result in fracture (especially because angled loads are placed on the facial-positioned implant). e manufacturers thicken the prole of the abutment on the facial aspect to reduce the risk of fracture. However, this design aw brings the cervical facial margin more facial and wider than the implant body, which is already as facial as the adjacent tooth. As a result, the implant crown margin is facially overcontoured. e restoring doctor then has to prepare the facial aspect of the abutment metal ange for esthetics, which weakens it and makes it prone to fracture. When the implant clinician attempts to align the implant body with the facial aspect of adjacent teeth, the implant may inadvertently be inserted too facial. No single method exists to restore proper esthetics when the implant abutment is located above the free gingival margin of the adjacent teeth. At best, the nal crown appears too long and too facial. Soft tissue grafts and/or bone augmentation do not improve the condition once the implant is already incorrectly inserted (Fig. 29.23).e natural maxillary anterior teeth are loaded at a 12- to 15-degree angle because of their natural angulation compared with the mandibular anterior teeth. is is one reason the maxil-lary anterior teeth are wider in diameter than mandibular ante-rior teeth (which are most commonly loaded in their long axis). e facial angulation of the implant body often corresponds to an implant body angulation, which leads to 15-degree o-axial loads and increases the force to the abutment screw-implant-bone com-plex by 25.9% compared with a long axis load. ese oset loads increase the risks of abutment screw loosening, crestal bone loss, and cervical soft tissue marginal shrinkage. In summary, implants angled too facially compromise the esthetics and increase the risk of complications (Fig. 29.24). Cingulum Implant Body AngulationA second angulation suggested in the literature is more palatal, with an emergence under the cingulum of the crown. is also may be the result of an implant insertion in a width-decient ridge (division B) because the bone is lost primarily on the facial. is position is often the goal when a screw-retained crown is used for the prosthesis. e prosthesis xation screw (to retain a maxillary anterior crown) cannot be located in the incisal or facial region of the crown as this will impinge on the esthetics.e cingulum implant position may result in a considerable compromise. e implant body is round and usually 4.0 to 5.5 mm in diameter. e labial cervical contour of the implant crown must be similar to the adjacent teeth for the ultimate esthetic eect. Because the long axis of the implant for a screw-retained crown must emerge in the cingulum position, this most often requires a facial projection of the crown or “buccal correction” fac-ing away from the implant body. e facial ridge lap must extend 2 to 4 mm and is often similar in contour to the modied ridge lap pontic of a three-unit xed prosthesis (Fig. 29.25).e modied ridge lap crown has become a common solution to correct the esthetics of the restoration when the implant is placed in narrow bone or follows a palatal angulation position. However, plaque control on the facial of the implant is almost impossible. Even if the toothbrush could reach the gingival sulcus, no hygiene device could be manipulated to a right angle to proceed into the facial gingival sulcus. As a result, although an acceptable esthetic restoration may be developed, especially with the additional cervi-cal porcelain, the hygiene requirements and present implant den-tistry standards render this approach nonideal (Fig. 29.26).Some authors argue that an improved contour may be devel-oped subgingivally with a palatal implant position. To create this contour, the implant body must be positioned more apical than desired. is position may prevent food from accumulating on the cervical “table” of the crown. However, the subgingival ridge lap does not permit access to the facial sulcus of the implant body for the elimination of plaque and to evaluate the bleeding index or facial bone loss. erefore the maintenance requirements for the implant facial sulcular region do not permit the clinician to consider this modality as a valid primary option.Greater interarch clearance is often required with an implant palatal position because the permucosal post exits the tissue in a more palatal position. Inadequate interarch space may especially hinder the restoration of Angle’s class II, division 2 patients, with the implant in this position. e bony ridge should be augmented if too narrow for the ideal implant diameter and position, or an alternate treatment option should be selected. AB• Fig. 29.19 (A) The ideal mesiodistal implant position for a central incisor is 0.5 to 1.0 mm more distal than the midtooth position. This decreases the risk of encroachment on the incisive canal. (B) The best mesiodistal position for a cuspid is centered in the cuspid position.• Fig. 29.20 Complete reection of lingual tissue to determine the position and size of the nasopalatine foramen and canal. The enlarged nasopalatine canal and foramen has led to compromised bone for implant placement. 716PART VI Implant SurgeryIdeal Implant Angulatione third implant angulation in the literature describes the most desirable implant angulation. A straight line is determined by con-necting two points. e clinician determines the line for the best angulation by the point slightly lingual to the incisal edge posi-tion of the implant crown and the midfaciopalatal position on the crest of the bone. e center of the implant is located slightly lingual to the incisal edge of the crown so that a straight abutment for cement retention emerges directly below the incisal edge (Fig. 29.27). Because the crown prole is in two planes, with the incisal edge more palatal than the cervical portion, the incisal edge posi-tion is perfect for implant placement and accommodates some of the facial bone loss that often occurs prior to implant placement. e facial emergence of the crown mimics the adjacent teeth, proceeding from the implant body under the tissue. e angle of force to the implant is also improved, which decreases the crestal stresses to the bone and abutment screws. When in doubt, the ABC• Fig. 29.21 Three implant positions are found in the literature related to the nal crown position. (A) A position below the incisal edge is best used for a cemented crown in the esthetic zone. (B) An implant is in the position of the natural root of the tooth. Although this makes sense, it places the implant too facial, and an angled abutment is usually necessary. (C) An implant in the cingulum position that is used when a screw-retained crown is the treatment of choice. This position requires a facial ridge lap of porcelain when used for FP-1 prostheses in the esthetic zone.• Fig. 29.22 Natural tooth has very thin facial cortical bone over the root, and the incisal edge of the crown is 12 to 15 degrees palatal to the facial emergence prole. This is not an ideal position for an implant. The bone to the palatal region is better suited for an implant and allows the implant to be positioned under the incisal edge.• Fig. 29.23 Implant placement too facially positioned. Soft tissue grafts will not correct the malpositioning and usually the most ideal treatment is implant removal and re-positioned in a more ideal position.• Fig. 29.24 Facially positioned implant leading to compromised esthetics.• Fig. 29.25 Implant placed in the cingulum position will usually require a ridge lap on the implant crown to restore the facial contour of the tooth. 717CHAPTER 29 Maxillary Anterior Implant Placementclinician should err toward the palatal aspect of the incisal edge position, not to the facial aspect, because it is easier to correct a slight palatal position in the nal crown contour compared with the implant body angled too facial.e implant abutment selected for a maxillary anterior single-tooth implant is most commonly used for a cemented restoration; however, screw-retained prostheses are becoming more popular. A greater range of corrective options exists with a cement-retained crown for implants, especially if it is not ideally positioned. e location of the cervical margin of a cemented crown can be any-where on the abutment post or even on the body of the implant provided it is 1 mm or more above the bone.e implant body angulation under the incisal edge may also be used for screw-retained restorations. In these cases an angled abutment for screw retention is placed, and the coping screw for the crown may be located within the cingulum. is method does not require a facial ridge lap of the nal crown, which decreases the risk of compromised hygiene. When ideal bone volume is present, a surgical template that ideally correlates the incisal edge and facial contour of the nal prosthesis may be used. Soft Tissue Incision: Surgical ProtocolObtaining and maintaining the ideal tissue drape is often the most dicult aspect of maxillary anterior single-tooth replace-ment within the esthetic zone. Several dierent approaches have been advocated to enhance the soft tissue appearance. e approaches may be surgical (addition or subtraction) or prosthetic and include (1) a soft tissue graft before bone augmentation, (2) a soft tissue augmentation in conjunction with a bone graft before implant insertion, (3) soft tissue augmentation in conjunction with implant insertion, (4) soft tissue manipulation at the implant uncovery procedure, (5) a prosthetic modication of interproxi-mal contact position, (6) creeping attachment around the implant crown, or (7) a prosthetic replacement of the soft tissue with pink-colored porcelain (Box 29.2).Surgical additive techniques such as pouch procedures, interpositional grafts, sliding aps, and connective tissue grafts (autogenous or acellular dermal matrix) have all been proposed. A soft tissue graft may be performed as a separate procedure before any other surgery when the patient has a high lip dynamic and the soft tissue color and/or volume is grossly decient. Most often, a connective tissue graft to improve the soft tissue drape is indicated.A bone graft and soft tissue augmentation is indicated when the bone on the adjacent teeth is within normal limits (2 mm below the CEJ) but decient in width and midcrestal volume. When the interproximal bone is not within normal limits, orthodontic extrusion maybe an option, followed by a crown and possibly end-odontic therapy. e goal of a soft tissue augmentation for either of the two previous procedures is to obtain soft tissue on the crest of the ridge at the height of the interproximal papilla height.ABC• Fig. 29.26 (A) The maxillary left central incisor (right side) with a ridge lap crown presents acceptable esthetics. (B) However, probing on the facial aspect measures the distance to the implant but cannot evaluate facial bone loss because it cannot be directed apically to the pocket depth. (C) Periodically, the left central incisor implant becomes inamed, and the bleeding index increases as a result of the inability to clean the implant sulcus on the facial. 718PART VI Implant SurgeryWhen elevating the interproximal tissue in the anterior max-illa, “papilla-saving” incisions are made adjacent to each neigh-boring tooth (Fig. 29.28). e vertical incisions are made on the facial aspect of the edentulous site and begin 1 mm below the macrogingival junction, within the keratinized tissue. Extending the vertical incisions beyond the macrogingival junction increases the risk of scar formation at the incision site. e full-thickness incision then approaches the crest of the edentulous site, leaving 1.0 to 1.5 mm of the interproximal papilla adjacent to each tooth. e vertical incisions are not wider at the base than the crestal width of tissue. is permits the facial ap to be advanced over the implant or short and adjacent to a healing abutment at the conclusion of the procedure, with no voids at the incision line and primary closure.When the papillae are depressed in the edentulous site, verti-cal-release incisions are made along the root angle of each adjacent tooth, beginning 1 mm below the macrogingival junction and in the sulcus of each adjacent tooth. erefore the interproximal papilla region becomes part of the facial soft tissue ap.e crestal incision is made on the palatal incline of the eden-tulous site to provide greater thickness of keratinized tissue on the facial aspect of the ap. is also allows more interproximal tissue to be elevated to enhance the papilla height.e soft tissue is reected, and the crestal bone width of the ridge is evaluated. When a central incisor site is reected, the pala-tal ap is reected to the incisive foramen for identication and evaluation. On occasion, its position may require the soft tissue to be enucleated and a graft positioned in its site. An initial pilot drill is positioned in the midmesiodistal and faciopalatal aspect of the ridge and proceeds approximately 7 to 9 mm within the bone under copious cooled sterile saline. A direction indicator is posi-tioned into the site for evaluation to determine the implant posi-tion with respect to the facial, palatal, mesial, and distal implant position. A periapical radiograph is taken, and the initial oste-otomy in relation to the adjacent roots and opposing landmark (i.e., oor of nose) is assessed. If adjustments are required, then a side-cutting drill (i.e., Lindemann drill) may be used.e second drill is used to increase the depth and width of the osteotomy at approximately 2000 rotations per minute (rpm) (in D1 and D2 bone) under copious amounts of cooled sterile saline. e osteotomy drilling should be completed with a “bone-dancing” preparation to avoid overheating the bone. If the bone density is D3 or D4, lower rotations per minute may be used (∼1000 rpm). If a surgical guide is not used, then the angulation of the drill should be within the long axis of the intended implant position to coincide with the lingual aspect of the incisal edge. If the osteotomy is not ideally positioned, then the side-cutting drill (Lindeman) is introduced into the osteotomy, and the palatal bone is removed by “shaving” up and down in the palatal aspect of the preparation.e nal size osteotomy drill is used to complete the osteot-omy according to the bone density surgical protocol. In general, a crestal bone drill and bone tap should not be used in the maxil-lary anterior region because the maxillary bone usually has little to no cortical bone present on the bony crest. Using a crestal bone bur will often lead to a decreased primary stability of the implant and reduced facial bone thickness.e threaded implant is inserted with a handpiece at 30 rpm because this is the most accurate insertion technique. Placing an BA• Fig. 29.27 (A) The perfect position for an anterior single-tooth implant is under the incisal edge to the approximate midcrest position. A central incisor should have the position slightly distal and slightly toward the palate. (B) The implant crown has a 1.0- to 1.5-mm subgingival margin and begins a facial, mesial, and distal contour at this point to exit the tissue similarly to the contour of the adjacent tooth.Preprosthetic Surgery• Softtissuegraftbeforeboneaugmentation• Softtissuegraftinconjunctionwithbonegraftbeforeimplantsurgery Surgery Stage I• Softtissueaugmentation• Nonresorbablehydroxyapatitegraft• Linguallyorientedincisiontopositionmoretissuetothefacial• Papillasavingincisions Surgery Stage II• Connectivetissuegraft(subepithelial)• Softtissueplasticsurgery• Gingivoplasty(coarsediamond)• Prosthetics• Widehealingabutment• Temporarycontouringthroughprovisionalrestoration• Anatomicabutment,tooth-coloredabutment• Pinkporcelain/zirconiaonabutment• Linguallyorientedincisiontopositionmoretissuetothefacial • BOX 29.2 Soft Tissue Contouring and Emergence Prole 719CHAPTER 29 Maxillary Anterior Implant Placementimplant with an insertion wrench may lead to possible misdirec-tion of the implant, most commonly being pushed to the facial. When a handpiece is used, counterforces on the handpiece handle and the ngers of the other hand on the handpiece head may per-mit the implant to be inserted without compromise to angulation or position.e implant is rotated in nal position, with a attening of the antirotational component to the facial (i.e., depending on the implant type and design). e implant mount may be removed, and the clinician decides whether a low-prole cover screw (two stage) or healing abutment (one stage) is used within the implant. When the hard and soft tissue contours are ideal and a papilla-saving incision was made, a healing abutment may be used. When a bone graft is placed and/or the crestal tissue elevated to increase the height of the papilla, a low-prole cover screw is more often used to allow for undisturbed healing. Once the cover screw is inserted, the clinician decides whether a bone graft on the facial bone is indicated. When the facial bone over the implant is less than 1.5 mm thick, bone from the osteotomy is ideally used over the facial aspect along with a collagen membrane. If tissue thick-ness is required, an acellular dermal matrix may be used instead of the collagen membrane (Fig. 29.29) to increase the bulk of tissue, therefore allowing for a more esthetic result. Soft Tissue Closuree soft tissue is approximated and sutured with a resorbable suture material (most commonly 4-0 or 5-0) around the healing abutment or over the cover screw, depending on whether the tis-sue is at the ideal position or is being augmented. e increased tissue thickness from augmentation facilitates the sculpting of interdental papillae at stage II surgery, improves ridge contour, and prevents the grayish hue of the titanium implant body from showing through the labial mucosa in the event of crestal bone loss in the future. Transitional ProsthesisA soft tissue–borne transitional prosthesis is not recommended because this may increase crestal bone loss during the healing period. In addition, it may depress the interdental papillae of the adjacent teeth. For a single tooth edentulus area, a resin-bonded xed restoration may be fabricated to provide esthetics and improve speech and function, especially when crestal bone regen-eration is performed. When a resin-bonded restoration is used, the adjacent teeth are not prepared and the prosthesis is bonded to the tooth regions below the centric occlusal contacts of the teeth.Papilla intact IncisionPapilla depressedAB• Fig. 29.28 (A) When the interdental papillae are in an acceptable position, papilla-saving incisions are made to minimize soft tissue reection. The incisions are vertical to allow primary closure. When the papillae are depressed, the vertical release incisions include the papilla in the edentulous site. (B) In situ-ations with a more depressed soft tissue, facial soft tissue and papillae over each adjacent tooth are also reected. The crestal incision is positioned towards the palatal incline on the ridge. 720PART VI Implant SurgeryFor multiple missing maxillary anterior teeth, a removable par-tial or full arch prosthesis (Smile Transitions™ - Glidewell Labora-tories) maybe utilized during the healing period. e prosthesis is retained by the remaining natural teeth, thereby preventing pres-sure or impingement on the soft tissues overlying the surgery site. (Fig. 29.29).Other options include an Essix appliance, which is an acrylic shell, similar to a bleaching tray, that has a denture tooth attached to replace the missing tooth. is prosthesis is the easiest for tooth replacement after surgical procedures. Another option may include a cast-clasp removable partial denture (RPD) with indirect rest seats to prevent rotation movements on the surgical site (Fig. 29.30).In some cases, an immediate placement/loaded prosthesis may be used; however, this needs to be completed under ideal conditions (e.g., favorable primary stability and insertion torque, bone density, lack of parafunction). e benets of immediate implant insertion after tooth extraction are related to an improved preservation of the soft tissue drape and the bone architecture compared with their col-lapse after tooth extraction. As a result, bone augmentation and soft tissue grafts may be avoided. e procedure has been described as a preservation technique aiming at maintaining the harmonious gin-gival architecture. e procedure also reduces the number of surgi-cal procedures, which may decrease the cost to the patient. Complicationse primary esthetic complications of maxillary anterior single-tooth implants include interdental papillae deciency and gingival shrinkage after crown delivery.Interdental Papilla Deficiencye interproximal CEJ of a natural tooth exhibits a reverse scallop toward the incisal edge. e same pattern is followed by the alveo-lar interproximal bone, which is more coronal in the interproximal regions than in the facial or lingual plates. As a consequence, the probing depth in the papilla region of a natural tooth is quite similar to the facial or palatal probing depths. Interproximal bone around an implant does not follow such a contour. As a result, the interdental papillae, which look natural and rise to ll the interproximal regions between healthy adjacent teeth, exhibit greater probing depths than the other surfaces of the implant crown. In fact, because the inter-proximal bone height also may be lost next to the adjacent teeth, the dental and implant papilla also correspond to a greater proximal prob-ing depth next to the natural tooth. A greater sulcus depth increases the risk of shrinkage after gingivoplasty, or later, even with good daily hygiene care. As a result, even years later the tissue may shrink and result in a poor interproximal esthetic situation (Fig. 29.31).As previously addressed, four surgical time sequences exist to address the interproximal tissue height: (1) before a bone graft with a connective tissue graft; (2) in conjunction with a bone graft, often using an acellular tissue graft (i.e., OrACELL; Salvin, Char-lotte, North Carolina); (3) at implant insertion, with an elevation of the tissue over a healing abutment and (4) at implant uncovery (i.e., split-nger technique). ere are several other methods to improve the soft tissue drape. ese approaches used to modify the soft tissue are prosthetic-related methods.e most common prosthodontic solution to alleviate soft tis-sue limitations is helpful when soft tissue surgery has not recreated ABC• Fig. 29.29 Removable Interim Prosthesis: (A) Maxillary anterior surgery site, (B) Smile Transitions interim prosthesis which is durable and highly esthetic that prevents pressure on the surgical site, (C) Removable pros-thesis in place.• Fig. 29.30 Hawley appliance with the addition of a denture tooth, may be used as an interim prosthesis 721CHAPTER 29 Maxillary Anterior Implant Placementan ideal interproximal papilla height. e interproximal region may be treated similarly to the pontic interproximal region of a three-unit FPD (Fig. 29.32). Rarely are interdental papillae present next to the pontics of a xed prosthesis. Instead, rather than raising the tissue to the interproximal contact of the crown, the interproximal contact is extended toward the tissue, and the cervical region of the pontic is slightly overcontoured. A similar approach may be applied to the single-tooth implant. e inter-proximal contacts of the adjacent teeth are recontoured, especially on the palatal line angle, to become oblong and extend toward the tissue. e contact areas of the single-tooth crown are extended, especially on the palatal line angle, toward the gingiva. e cervi-cal region of the single-tooth implant is slightly overcontoured in width, similarly to the pontic of a xed prosthesis. is concept does slightly compromise the interproximal esthetics. e papilla is not as high next to the implant crowns as it is between the natu-ral teeth, and the cervical width of the crown is 0.5 mm wider.However, the sulcus depth is reduced on the tooth and implant crown, and the daily hygiene conditions are improved. In addi-tion, long-term shrinkage of the tissue is less likely to occur. is option should be the method of choice whenever possible and especially when the high lip position during smiling does not dis-play the gingival regions around the teeth. Nasopalatine (Incisive) Foramen and CanalAnatomye nasopalatine (incisive) canal connects the oral cavity (naso-palatine foramen) with the oor of the nasal cavity. e soft tissue overlying the foramen is often associated with two lat-eral canals, which often fuse before exiting the foramen.27 e maxillary division of the trigeminal nerve gives o the naso-palatine nerve branch, which enters the posterior nasal cavity via the sphenopalatine foramen, transverses the roof of the nose and proceeds along the nasal septum in between the periosteum and mucosa before exiting the nasopalatine foramen.28 Mraiwa and colleagues reported that the nasopalatine foramen is located approximately 7.4 mm from the labial surface of an unresorbed maxillary anterior ridge and that the distance will vary after the amount of osseous resorption after extractions. e mean diam-eter of the nasopalatine foramen was shown to be approximately 4.6 mm (range, 1.5–9.2 mm).29 e length of the nasopalatine canal has been reported to be approximately 9 mm, with a range of 3 to 14 mm.30 e average height has been documented to be approximately 10.08 to 10.86 mm.31,32 However, as the premax-illa resorbs, the nasopalatine canal decreases in size.33 When the maxillary premaxilla alveolus resorbs in height, the incisive canal reduces in length; therefore division A, B, and C–w bone has greater canal length than division C–h and D bone. e angle of the nasopalatine canal has been shown to vary from 46 to 99 degrees with respect to the horizontal plane with a mean angula-tion of 66 degrees.34 A vertical projection above the incisive canal along the nasal oor is called the premaxillary wing. e nasal process of the maxillary premaxilla rises 2 to 3 mm above the nasal oor (Fig. 29.33). Surgical Approaches to the Nasopalatine CanalIn most cases, an implant may be positioned to replace a central incisor without encroaching on the nasopalatine canal. However, if extensive resorption or a large canal is present, then the nasopalatine canal may have a direct eect on the implant positioning. erefore ideally the implant should never contact any soft tissue contents of the canal. To avoid this from occurring, there exist several approaches when the nasopalatine directly aects the implant positioning. Kraut et al reported that approximately 4% of nasopalatine canals directly aect the ideal positioning of implants in the premaxilla.• Fig. 29.31 Most common esthetic complication in the premaxilla is the inadequate soft tissue drape around an implant crown. The patient’s left central incisor exhibits black interproximal spaces.AB• Fig. 29.32 (A) A prosthetic solution for inadequate papilla height is to lower the interproximal contact of the crown by reshaping the adjacent teeth. (B) The canine implant crown lls the space and eliminates the inter-dental spaces caused by the lack of papilla height. 722PART VI Implant SurgeryBone Grafting the Nasopalatine Canal with Delayed Implant PlacementOne option when the size and position of the nasopalatine canal impinges on the implant placement is to enucleate and bone graft the canal. e nasopalatine canal is exposed by full-thickness reection and the soft tissues within the canal are entirely curet-ted. Serrated spoon excavators (e.g. Lucas 86) may be used along with a round carbide bur to completely remove any soft tissue remnants from the canal. Rosenquist and colleagues rst reported on removing the contents of the nasopalatine canal and autog-enous bone grafting the area. Implant placement was delayed for approximately 5 months with a 100% success.35 Since then, numerous additional studies have shown positive outcomes with this procedure including guided bone regeneration techniques along with grafting the nasopalatine canal (Fig. 29.34).36,37 Removal of the Canal Contents + Implant PlacementA second option includes the enucleation of the nasopalatine canal followed by immediate implant placement. e incisive foramen is first reected and identified, and a periodontal probe evaluates the angle and depth of the bony canal to ensure a minimum length of 9 mm. e soft tissues in the incisive canal are curetted from the canal site, which is approximately 4 mm in diameter at its apex. A round carbide bur (e.g. # 6 or # 8 round bur) in a straight handpiece may be used to remove the soft tissue remnants. In addition, the trauma from the round bur initiates the regional acceleratory phenomenon (RAP), which allows for more predictable healing (Fig. 29.35).Once the soft tissue is removed, drills progressively increase the diameter to the final implant osteotomy diameter 2 mm below the final height of the canal. A blunt osteotome and gentle, sudden impact force with a mallet then prepares the apical 2 mm of the implant site. A large-diameter threaded implant (>5 mm) is gener-ally used and should be greater than the diameter of the foramen (Fig. 29.36). When the foramen diameter is greater than that of the implant available, the canal is augmented with an autologous or allograft bone graft, and the implant insertion is delayed for several months. is technique is often clinically challenging. Positioning the Implant Away From the Nasopalatine CanalIn the literature, some authors have suggested placing the implant in a nonideal position to avoid the nasopalatine canal. If the intended prosthesis is an RPD, the implant may be positioned to avoid penetration into the canal. e most common position would be in the embrasure area of the central and lateral position. is would result in maintaining the anteroposterior spread, along with not penetrating into the canal. However, care should be exer-cised not to angulate the implant too far to the facial as this may impinge on the esthetics of the prosthesis.Kraut and colleagues evaluated CBCT scans and found that 4% of the time the nasopalatine canal would interfere with the normal preparation of an osteotomy for an implant.38Mardinger and colleagues reported that after extraction the average length of the canal shortened from 10.7 to 9 mm and the nasopalatine foramen encompassed 36.5% of the ridge width (range, 13%–58%) as it enlarges in all directions. In severely resorbed ridges, the nasopalatine foramen enlarged by 32% AA BCD• Fig. 29.33 Nasopalatine canal and foramen. (A) Large nasopalatine canal. (B) Large nasopalatine fora-men. (C) Clinical image of nasopalatine foramen exposure, which compromises implant placement in the central incisor region. (D) Attempting to place implant in cases with large nasopalatine canal leads to penetration into the canal and a soft tissue interface. 723CHAPTER 29 Maxillary Anterior Implant Placement(1.8mm) and reached approximately 5.5 mm in diameter, which could occupy up to 58% of the ridge.39Another technique for a xed prosthesis is to angulate the implant intentionally, often placing the implant at an increased apical position. e theory includes allowing more space (i.e., running room) for the prosthesis that creates a more favorable emergence prole. However, this technique does increase the crown height space, which is a force magnier. In addition, adja-cent teeth may be compromised periodontally. Complications of Nasopalatine ImplantsMigrated ImplantSome rather signicant complications may be associated with incisive canal implants. e first surgical complication of an inci-sive foramen implant is related to the implant that is too small for the foramen and not properly fixated (i.e., inadequate primary stability). e implant may be inadvertently pushed through the incisive canal and into the nares proper. Because patients are in a supine position during the surgery, the implant may fall back into the soft plate, then into the trachea or esophagus. If the implant disappears from the oral site, the patient’s head should be turned to the side immediately, then down and forward. A nasal specu-lum and tissue forceps may then be used to recover the implant or immediate medical referral. Excessive BleedingA second surgical complication may include excessive bleeding from the incisive foramen. Although this complication is very rare, it is possible. When reection of the palatal tissue o the incisive canal is associated with arterial bleeding, a blunt bone tap (mirror handle) may be placed over the canal and a mallet used to hit the instrument firmly, crushing the bone over the artery. After several minutes the procedure may continue, and the implant insertion A BC• Fig. 29.34 Bone graft with delayed implant placement. (A and B) Ridge augmentation to gain width of bone so implant placement does not impinge on the nasopalatine foramen. (C) Ideal implant placement.AB• Fig. 29.35 (A) Implant placement into the nasopalatine canal for a removable implant-supported overdenture. By placing an implant in the nasopalatine canal, the anteroposterior spread is increased. (B) Clinical image depicting implant in the nasopalatine canal. 724PART VI Implant Surgerywill obdurate the site and arrest the bleeding. Additional tech-niques include the use of injecting epinephrine 1:50,000 directly into the foramen. An electrocautery unit may also be used with a ball type of attachment.40 Neurosensory ImpairmentA third complication of an nasopalatine foramen implant is associ-ated with enucleation of the soft tissue from the foramen, which may result in neurologic impairment of the soft tissues in the ante-rior palate. ese complications may be anesthesia or paresthesia to the soft tissue or a dysesthesia, resulting in a burning sensation, which have been reported in numerous reports.41,42 In most cases, collateral innervation from the greater palatine nerve to the ante-rior palate is present which eliminates any possible neurosensory disturbances. Tissue Regeneratione fourth complication is a long-term complication which may include the regeneration of the soft tissue in the incisive canal, result-ing in bone loss and failure of the implant (Fig. 29.37). When the implant is removed and the soft tissue biopsied, nerve fibers can be seen reinvading the site. is most likely occurs because the implant ABCDEF• Fig. 29.36 (A) The incisive foramen was excavated and prepared for an implant. The site may be bone tapped before implant insertion. (B) A 5-mm-diameter implant is inserted into the incisive foramen after implant preparation. (C) A stage II reentry reveals bone around the incisive foramen implant. (D) On occasion, a xed prosthesis may be fabricated with the anterior implants in the canine and incisive foramen position. (E) A panoramic radiograph of the incisive foramen implant, bilateral sinus grafts, and nine implants (includ-ing the canine positions). (F) A periapical radiograph of an incisive foramen implant after 5 years of function. 725CHAPTER 29 Maxillary Anterior Implant Placementwas too small for the size of the foramen, and the soft tissue can reform around the implant. Treatment of this complication includes removing the implant and, if necessary for the treatment plan, regraft-ing and/or reimplantation at a later date. Implants in Approximation to the Nasal CavityAnatomic Considerationse anterior nasal spine has an anterior component that averages 4.1 mm (0–9 mm) in adults.27 Posterior and lateral to it, two at processes, the alae of the premaxilla, project superiorly and laterally. e piriform aperture is bounded below and laterally by the maxilla. e breadth of the piriform aperture in adults ranges from 20 to 28 mm and averages 23.6 mm.43,44 e lower border of the inferior piriform rim may be sharp or rounded. is border often rises from the premaxillary bone and ends anteromedially in the anterior nasal spine. e anatomy of the nasal oor is variable in relation to the inferior turbinate and is typically situated 5 to 9 mm below the level of this structure (Fig. 29.38).45When maxillary anterior teeth are present or have maintained the residual bone, the inferior piriform rim is usually level or a few millimeters above the oor of the nose in the central and lateral region.46 e inferior piriform rim above the nasal oor forms a prenasal fossa, which is found in 12% of patients.47 In these cases a shallow depression extends toward the alveolar arch behind a sharp border of the inferior piriform rim. As a result, when the inferior piriform rim is used as a guideline for the height of the opposing cortical plate from the crest of the ridge in the maxilla during surgery to determine implant length, the lowest portion of the nasal oor and nasal mucosa may be inadvertently perforated during the implant osteotomy and placement. Ideally, implant placement should be short of the nasal oor.ABCDEE• Fig. 29.37 (A) A long-term complication of an incisive foramen implant may be bone loss around the implant that extends the full length of the implant. (B) When more than 50% of the implant has been lost, it should most often be extracted. A trephine bur may remove the integrated portion of the implant. (C) The implant removed is surrounded by soft tissue. (D) Histologic examination of the soft tissue around the implant reveals that the contents of the incisive canal are reforming around the implant. (E) Histologic examination demonstrates nerve bers in the soft tissue around the implant.• Fig. 29.38 Natural canine root is distal to the lateral piriform rim of the nose. However, a nasal recess extends distal, behind the piriform rim and over the canine site of a resorbed maxilla, which is more palatal than the tooth root position. The inferior concha of the nose is 4 to 6 mm superior to this recess region. 726PART VI Implant Surgerye canine tooth position is immediately distal to the lateral piriform rim. e canine eminence in this area is lost after sev-eral years of edentulism, and the crest of the residual C–h bone volume ridge is palatal to the original tooth position. e nasal cavity is usually above, medial, and palatal to the canine position in the dentate patient. However, a nasal recess is present behind the lateral piriform rim. is nasal recess corresponds to the api-cal region of the canine position in the C–h maxilla, which has resorbed palatally and is now under the nasal cavity. Implants placed in the canine position of a C–h bone volume may extend more superiorly than the natural canine root.e arterial blood supply to the nose is derived from both the external and internal carotid arteries. e terminal branch of the maxillary artery (a branch of the external carotid) supplies the sphenopalatine artery, which supplies the lateral and medial wall of the nasal chamber. e anterior and posterior ethmoid arteries (branches of the ophthalmic artery) supply the nasal vestibule and the anterior portion of the septum. In addition, a few vessels from the greater palatine artery pass through the incisive canal of the pal-ate to reach the anterior part of the nose. At the junction between the squamous epithelium of the nasal vestibule and the respiratory epithelium of the nasal cavity lies a strip about 1.5 mm wide cover-ing a region of wide and long capillary loops, known as Kiesselbach’s plexus.48 It extends to the lower and central part of the cartilaginous septum and is a common region for nose bleeds (Fig. 29.39).Ideally, dental implants should be positioned short of the nasal cavity. Wol and colleagues reported a case report describing an implant placed into the nasal cavity resulting in severe congestion postop. erefore dental implants protruding into the nasal cavity may cause alterations in airow. If this should occur, the implant should be removed or the apical portion of the protruding implant may be removed via a transnasal approach (Fig. 29.40).49 Maxillary Anterior Anodontiae most common maxillary anterior tooth replaced by an implant is a central incisor lost from trauma (e.g., endodontic failure, frac-ture, root resorption) and/or a lateral incisor absent as a result of agenesis. e absence of one or more teeth is known as anodontia and may be complete (very rare) or partial (also called hypodon-tia). It is many times more common than supernumerary teeth. e primary cause of partial anodontia is familial heredity, and incidence ranges from 1.5% to as high as 10% in the US popula-tion.50 e genetic predisposition has been associated with PAX9 promoter polymorphisms.51 In addition, a number of syndromes exist in the literature that include multiple missing teeth, of which ectodermal dysplasia is the most common.A high correlation is found between primary tooth absence and a permanent missing tooth; however, a missing tooth occurs more frequently in the permanent dentition. Caprioglio and colleagues52 evaluated the records of almost 10,000 patients between the ages of 5 to 15 years of age. Of all the missing single teeth, the mandibular sec-ond premolar was most often missing (38.6%), followed by the max-illary lateral incisor (29.3%), the maxillary second premolar (16.5%), and the mandibular central incisor (4.0%). e remaining teeth were absent at a rate of only 0.5% to 1.8%, with the maxillary rst molar being the least aected. e missing mandibular second premolar pri-marily occurred in male patients, whereas the maxillary lateral incisor primarily occurred in female patients. e most common multiple teeth lost (other than third molars) are the maxillary lateral incisors, followed by the mandibular second premolars and maxillary second premolars. Congenitally missing teeth are therefore a common sce-nario seen in dental practices today. Fortunately, less than 1% of those missing teeth are missing more than two teeth, and less than 0.5% of this group are missing more than ve permanent teeth.When acceptable conditions can be created, an anterior single-tooth implant is the treatment of choice for a congenitally missing anterior tooth. However, the treatment of congenitally missing teeth are very challenging with signicant esthetic and functional demands.e replacement of congenitally missing teeth usually occurs during the adolescence period. Because of this patient population, many issues complicate the treatment including (1) interdisciplin-ary approach, (2) postorthodontic retention, (3) implant place-ment timing, (4) ideal placement is required, and (5) associated esthetic and soft tissue problems exist.is condition is especially benecial for a lateral incisor because the ideal cervical region of the tooth is similar to the implant diam-eter. However, the roots of the adjacent natural teeth often impinge BA• Fig. 29.39 (A and B) Implant placement into the nasal cavity proper is not recommended because irrita-tion and nasal congestion problems may result. 727CHAPTER 29 Maxillary Anterior Implant Placementon the edentulous space, resultying in insucient mesial-distal space for a dental implant. As a consequence, orthodontic therapy before implant placement should often be considered. An additional advantage of orthodontics before or in conjunction with implant treatment for the congenital missing tooth is that the missing lateral incisor may be restored provisionally by a denture tooth attached to the orthodontic wire to provide an esthetic replacement without trauma to the augmented ridge or implant during healing.e missing maxillary lateral incisor is most often replaced with a dental implant because the other orthodontic or prosthetic options are usually poor alternatives. e clinician should rst determine whether space-opening (maintenance) procedures or space closure (orthodontics) is the treatment of choice for the missing tooth. e treatment options are usually dierent for a mandibular second pre-molar compared with a maxillary lateral incisor.Graber53 noted a strong correlation between a missing single tooth and altered tooth size, shape, or both. A common condition is a miss-ing lateral incisor, in which the contralateral lateral incisor is smaller than usual or a peg lateral. As such, the mesiodistal space is often limited to less than 6.5 mm. In these instances, a nonfunctional, small-diameter implant of 3.0 mm may be considered. When the intratooth space is less than 5 mm, other treatment options should be considered including a cantilevered FPD from the canine abutment. Congenitally Missing Lateral Incisor Treatment ProtocolIn most cases of congenitally missing lateral incisors, orthodontic intervention is required. ere usually are three phases of treat-ment for the replacement of congenitally missing lateral incisors, (1) orthodontic treatment, (2) postorthodontic treatment, and (3) nal implant treatment.Orthodonticere are two dierent orthodontic treatments for the restoration of a congenitally missing lateral incisor: cuspid substitution (space closing)54 and conventional treatment (space opening).55With cuspid substitution, the permanent cuspid is orthodonti-cally repositioned into the lateral incisor space and the rst pre-molar into the canine space. e advantage of this treatment is that it uses conventional orthodontic treatment, which usually entails comprehensive orthodontic care. e disadvantage of this treatment is that most patients end up with a class 1 occlusion, therefore a malocclusion results. Usually, the patient will not have a cuspid disocclusion, but a group function will result. In addition, esthetically, the cuspid diers greatly in shape, size, and color compared to a lateral incisor. Usually the cuspid shade is one to two shades darker than the lateral, and if recontouring of the cuspid is completed, usually the show-through of the dentin will make the tooth even darker. e canine is normally 1 mm wider than the lateral incisor; reducing the interproximal areas of the tooth will result in further darkening.56 Last, the permanent cuspid is more convex than a lateral; therefore reshaping often will result in hypersensitivity and esthetic issues. e rst premo-lar is normally shorter and narrower than the contralateral cuspid (Fig.29.41).Conventional orthodontic treatment includes opening the space to allow for a future restoration, which usually includes an endosseous implant. e goal of conventional orthodontic treat-ment is to achieve ideal coronal and apical space for an implant, along with a favorable occlusal scheme for the nal prosthesis (Fig.29.42).e amount of space required is a minimum of 6 mm, which results from the “golden ratio.”57 e golden ratio describes the relationship between the central and lateral incisor, which states that the lateral incisor is 2⁄3 the size (mesiodistal width) of the cen-tral incisor. e average central incisor is 9 mm wide; therefore the lateral width would be 6 mm. Chu described another method of determining the width of the lateral incisor. With this method, the central incisor is determined to be “x.” e lateral incisor then is calculated as “x − 2 mm” and the cuspid is “x − 1 mm.”58 Last, the author uses a method that measures the contralateral side and duplicates that space in the nal restoration. In some cases, cos-metic bonding may need to be completed to make the spaces ideal. AB• Fig. 29.40 (A and B) Implant placement into the nasal cavity may result in compromised crown height space and irritation from violating the inferior meatus and turbinate. Note the implants are actually in con-tact with the turbinate. 728PART VI Implant SurgerySpacing RequirementsBefore placing an implant into a congenitally missing space, a CBCT should be obtained to determine the exact space between the adjacent teeth, both coronally and apically. In many cases, cli-nicians will determine whether there is adequate coronal space; however, the apical space is compromised. is often occurs when space is obtained by use of a palatal expander, and then the central incisors are “tipped,” instead of “bodily” moved back into posi-tion. By closing the space between the central incisors, the root apexes will be approximate, leaving inadequate space for a dental implant. In most cases, the interroot distance should be a mini-mum of 6 mm (Fig. 29.43).59,60 e minimum space required should be veried via a CBCT examination by measuring the coronal, midroot, and apical areas.Postorthodontic RetentionIn most cases of postorthodontic treatment, the patient is usu-ally too young for implant treatment. erefore it is impera-tive that patients are maintained during this period to prevent relapse. Postorthodontic retention usually is via a removable or rigid prosthesis. Common removable prostheses include a Hawley appliance or an Essix appliance.61 Unfortunately, api-cal relapse or reapproximation has been shown to occur in approximately 11% of postorthodontic cases because of retainer noncompliance, compensatory eruption, and increased vertical growth.62 Ideally, to prevent root approximation, a rigid, non-removable prosthesis should be used. Rigid retention usually involves the insertion of a resin-bonded bridge, which is advan-tageous because it is a nonremovable prosthesis; however, a high debonding rate is seen.63 Final ProsthesisFor a congenitally missing lateral incisor, an implant retained prosthesis is advantageous over all other options (e.g., resin-bonded prosthesis, FPD, cantilevered xed prosthesis, RPD). e clinician must evaluate and take into consideration the following factors when treatment planning for an implant prosthesis: tim-ing, available bone present, coronal and apical space, positioning, esthetics, and gingival contours.Timing. A common complication occurs when clinicians use chronologic age as the determining factor for the timing of implant placement. Ideally, implant placement should be com-pleted when the patient has facial growth cessation. In the lit-erature, growth cessation has been documented to be determined with the use of dental development,64 voice changes,65 hand–wrist radiographs,66 cervical vertebrae maturation,67 and serial lateral cephalometric radiographs.68 Unfortunately, most of the accurate options to determine growth cessation are via radiation exposure. erefore to reduce the radiation exposure to adolescent implant patients, the author recommends measuring growth cessation by monitoring stature growth, usually with the assistance of the patient’s pediatrician. Studies have shown that less than a 0.5-cm growth in a 6-month period is an ideal time to initiate dental implant treatment.69If implants are placed before growth cessation, the downward growth of the maxilla results in the implants being in infraocclu-sion compared with the natural teeth. When facial growth occurs, changes will result in tooth position. Because of the osseointegra-tion (i.e., ankylosis) of the dental implant, the dental implant can-not change position, which may result in esthetic complications.70 Westwood and colleagues reported implants placed at age 12 will AB• Fig. 29.41 Canine substitution. (A) Preoperative image depicting congenitally missing lateral incisors. (B) Final postoperative image showing canine repositioned into the lateral position and rst premolar reposi-tioned into the cuspid position.AB• Fig. 29.42 Conventional orthodontic treatment, (A) Preoperatively, congenitally missing laterals. (B) Post-operatively, canines repositioned into their ideal position allowing for future implant placement. 729CHAPTER 29 Maxillary Anterior Implant Placementbe in infraocclusion 5 to 7 mm 4 years later.71 Ranly showed that at age16 teeth are located approximately 10 mm coronally from their position at age 7.72 In general, implant submergence is not easily correctable. It may be possible to place a new prosthesis on the implant to correct the occlusal discrepancy, increased crown-implant ratio, and the poor esthetics. However, signicant bio-mechanical issues along with potential peri-implant disease may result. If eruption of the adjacent teeth occurs, remediation of the implant usually involves explantation of the implant, bone aug-mentation, and placement of a new implant (Fig. 29.44). Available Bone Present. Because the congenitally missing tooth does not have a permanent tooth bud, the available bone in the area most often is compromised in quality and quantity. In most cases, a division B or a division C–w is present. To obtain adequate bone for implant placement, bone augmentation is usually recommended. Bone augmentation maybe completed before growth cessation; however, it should be timed correctly with implant placement at the time of no future growth. In some cases, the permanent cuspid may be allowed to erupt mesially through the alveolus into the lateral incisor position. Because of its signicant buccolingual dimensions, the edentulous ridge is maintained. When the permanent canine is moved orthodontically into the ideal canine position, an increased buccolingual width will be retained (Figs. 29.45 and 29.46).73 BA• Fig. 29.43 (A) Ideal implant placement for lateral incisor, 1.5 mm from teeth and a 3.0-mm implant diam-eter. (B) Nonideal space caused by orthodontic tipping of the central incisors.AB• Fig. 29.44 (A) Implant placement too early. Because of continued growth of the maxilla, the implant (left central incisor) is positioned in infraocclu-sion. (B) Bilateral lateral incisors in infraocclusion. Note the tissue reces-sion and implant exposure of the maxillary right lateral incisor.• Fig. 29.45 Maxillary right lateral incisor showing compromised bone. Note the large concavity adjacent to the midroot of the adjacent teeth. 730PART VI Implant SurgeryACEFDB• Fig. 29.46 (A) Maxillary left congenitally missing lateral incisor. (B and C) Clinical images of compromised available bone and soft tissue. (D) Tissue reection showing large osseous defect, (E) autogenous bone graft, (F) postgraft healing,Continued 731CHAPTER 29 Maxillary Anterior Implant PlacementGHIJK• Fig. 29.46, cont’d (G) implant placement, (H) second-stage surgery with implant post placement to develop the soft tissue drape, (I) interim prosthesis fabricated to develop soft tissue, (J) papilla developed, and (K) nal implant prosthesis. 732PART VI Implant SurgeryCoronal and Apical Space. A CBCT examination should be completed to verify that a minimum of 6 mm of space is pres-ent coronally and apically. A minimum of 1.5 mm of space needs to be present between the nal implant position and an adjacent tooth root. If implant placement is too close to an adjacent tooth root, a number of complications may result, including devital-ization of teeth, development of pathology around the teeth or implant, sensitivity of teeth, and loss of teeth or implant. If the coronal space is compromised, apical migration of the papilla will occur, leading to open gingival embrasures and compromised gin-gival scallop (Figs. 29.47 and 29.48).74 Implant Positioning. Often, implants placed in the premax-illa are positioned too facially. is occurs because of a thin buc-cal plate and the existing bone trajectory. If an implant is facially positioned, then esthetic issues may result including tissue show-through of the implant or abutment and gingival recession (Fig. 29.49). In addition, bone loss may occur from unfavorable force factors. For a cement-retained prosthesis, the implant should be placed slightly lingual to the incisal edge of the tooth. For a screw-retained prosthesis, the implant should be positioned in the cingu-lum area. In the apicocoronal position, the implant body should ideally be positioned 2 to 3 mm below the free gingival margins of the central incisor and cuspid (Fig. 29.50).75 Soft Tissue Complications. Usually when a tooth is missing congenitally, the associated papilla will not be present. To increase the thickness of the tissue, acellular dermis (OrACELL) may be used at the time of bone augmentation or implant placement. After implant placement, tissue grafting is more dicult and less predictable. Another option to increase tissue thickness is the use of the split-nger technique, which is completed at the second-stage surgery appointment and uses a healing abutment to increase the size of the papilla.76 Last, the tissue can be guided via a provisional restoration. After implant healing is complete, a provisional restoration may be placed on the implant to prostheti-cally guide the soft tissue into an ideal position. e subgingival contours of a provisional prosthesis have been shown to inuence the nal position of the prosthesis (Fig. 29.51).77 Summarye replacement of missing teeth in the premaxilla is very chal-lenging because of the highly specic soft and hard tissue crite-ria, in addition to all other esthetic, phonetic, functional, and occlusal requirements. Maxillary anterior tooth loss usually compromises ideal bone volume and position for proper implant placement. Implant diameter, compared with that of natural teeth, results in challenging cervical esthetics. Unique surgical and prosthetic concepts are implemented for proper results. In spite of all the technical diculties that the surgical and restor-ing clinician may face, the anterior single-tooth implant is the ideal modality of choice to replace a missing anterior maxillary tooth. However, the clinician must have a strong foundation for the inherent complications that are involved with replacing max-illary anterior teeth.ABC• Fig. 29.47 Coronal space. (A) Nonsymmetric coronal space that is being remedied via conventional orthodon-tic treatment. (B) Cone beam computerized tomographic three-dimensional image measuring ideal space for implant. (C) Nonideal space for implants. The placement of implants places the adjacent teeth at signicant risk. 733CHAPTER 29 Maxillary Anterior Implant PlacementABC• Fig. 29.48 (A) Lack of Available bone for implants encroaching upon periodontal ligament space of adja-cent teeth, (B) Poor positioning leading to pathology involving the implant and natural tooth, (C) A CBCT examination should always be utilized to determine the available bone for implant placement. 734PART VI Implant SurgeryReferences 1. Priest GF. Failure rates of restorations for single tooth replacements. Int J Prosthodont (IJP). 1996;9:38–45. 2. Watson MT. Implant dentistry, a 10 year retrospective report. Dent Prod Rep. 1996:25–32. 3. Scurria MS, Bader JD, Shugars DA. Meta-analysis of xed par-tial denture survival: prostheses and abutments. J Prosthet Dent. 1998;79:459–464. 4. Goodacre CJ, Bernal G, Rungcharassaeng K, etal. Clinical com-plications with implants and implant prostheses. J Prosthet Dent. 2003;90:121–132. 5. 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