Alveolar Distraction
Osteogenesis for
Dental Implant
Preparat ion:
An Update
Luis G. Vega, DDSa,*, Arturo Bilbao, MD, PhDb,c
KEYWORDS
Alveolar distraction Alveolar reconstruction
Dental implants Bone grafting
distraction. This article discusses newer research
and provides clinical advice on the practice of
alveolar distraction osteogenesis.
BIOLOGY OF ALVEOLAR DISTRACTION
OSTEOGENESIS
Alveolar distraction osteogenesis uses biologic
principles described in the orthopedic literature.4,5
After performing an alveolar bone osteotomy,
a distractor device is placed in the transport
segment, which remains fully vascularized via its
periosteum. Subsequently, the bony segment is
subjected to gradual traction that separates it
from the basal bone; this traction activates tissue
growth and regeneration, forming a distraction
callus that progressively matures into bone. The
resultant bone mass and shape depends on the
vector of distraction, mechanical forces, and the
blood supply.
Several biologic processes occur during and
after distraction. In recent years, several publications have reported specifically on the biology of
human alveolar distraction osteogenesis.6–11
Chiapasco and colleagues8 reported that, after
12 weeks of consolidation, the percentage of
mineralized bone that formed in the distracted
a
Division of Oral & Maxillofacial Surgery, Department of Surgery, Health Science Center at Jacksonville,
University of Florida, 653-1 West 8th Street, Jacksonville, FL 32209, USA
b
Santiago de Compostela University Hospital, Travesı́a da Choupana s/n, 15706 Santiago de Compostela, La
Coruña, Spain
c
Private Practice, La Rosaleda Hospital Policlı́nico, Santiago León de Caracas, 1, 15701 Santiago de Compostela, La Coruña, Spain
* Corresponding author.
E-mail address: luis.vega@jax.ufl.edu
Oral Maxillofacial Surg Clin N Am 22 (2010) 369–385
doi:10.1016/j.coms.2010.04.004
1042-3699/10/$ – see front matter ª 2010 Elsevier Inc. All rights reserved.
oralmaxsurgery.theclinics.com
Current standards in implant dentistry are
intended to provide natural prosthetic restorations
with the finest esthetic and functional outcomes.
Several parameters have been suggested to
achieve gold-standard results: adequate bone
height, width, and anteroposterior projection;
adequate soft tissue quantity and quality; preservation of buccal sulcus; and adequate papillae
and gingival contour.1 The preservation and
reconstruction of the alveolar bone and
surrounding soft tissues for the placement of
dental implants has become fundamental in the
contemporary practice of oral and maxillofacial
surgery. As described elsewhere in this issue,
multiple techniques have been used for these
purposes.
Since its introduction in 1996,2 alveolar distraction osteogenesis has been considered a viable
technique for reconstruction of alveolar bone
before implant placement. In 2004, the Oral and
Maxillofacial Clinics of North America published
an article on alveolar distraction osteogenesis.
Batal and Cottrell3 comprehensively reviewed the
history, biologic principles, devices, clinical applications, and surgical techniques in alveolar
distraction osteogenesis, and readers are referred
to this text for the basic concepts on alveolar
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region ranged from 21.6% to 57.8%. The newly
formed bone was oriented perpendicular to the osteotomy cut and consisted of woven bone reinforced by parallel-fibered bone. Türker and
colleagues10 reported similar histologic findings
after 12 weeks of consolidation. They also correlated those findings with panoramic radiographs,
dental computed tomography (CT) scans, and
bone density analysis. Panoramic radiographs at
the end of distraction showed radiolucent gaps;
after 12 weeks the distraction gaps appeared to
be mostly radio-opaque with some radiolucent
areas, and after 1 year the appearances were the
same as the preexisting bone. Dental CT scans
taken 12 weeks after distraction confirmed the
increase of alveolar heights and filling of the
distraction chamber; after 1 year the CT scans
showed formation of bone that appeared similar
to preexisting bone. Bone density analysis from
the dental CT showed that the newly formed
bone after 12 weeks of consolidation was denser
than medullary bone. Iizuka and colleagues6 found
that a bidirectional alveolar distractor formed highdensity new bone with complex architecture. The
new bone was oriented in several different layers.
They concluded that the favorable bone regeneration was achieved as a result of the combination of
slow distraction and gradual anterior angulation.
Consolo and colleagues7 compared the use of
traditional alveolar distraction with an intermittent
loading alveolar distraction. After reaching the
distraction goal, the individual started an activation-deactivation protocol for 8 weeks during the
consolidation phase. The histologic results at 6, 8,
and 12 weeks of consolidation showed evidence of
early bone formation with superior structure quality.
Adequate blood supply is crucial for the development, remodeling, and regeneration of bone.
Amir and colleagues9 found a positive correlation
between blood vessel volume and bone volume
density in newly formed bone after alveolar distraction. This finding supports the concept that vascularity is necessary for the formation of new bone.
Lindeboom and colleagues11 reported on the
vascular density changes in oral mucosa after
alveolar distraction. They showed that the main
increase of vascularity was during the activation
phase. The vessel density during consolidation
was comparable with preoperative levels.
phases of distraction remain the same: osteotomy,
latency, distraction, and consolidation (Fig. 1).
Osteotomy
Osteotomy has traditionally been performed with
rotary burs, different kinds of saws, and osteotomes. Piezosurgery for alveolar distraction
osteotomies has also been reported in the literature.12,13 By comparing piezoelectric with conventional osteotomies for alveolar distraction,
González-Garcı́a and colleagues13 found that the
surgical difficulty and the incidence of intraoperative complications were significantly lower in the
piezoelectric group. Their results showed that the
postdistraction alveolar morphology was worse
in the piezoelectric group. They theorize that the
piezoelectric osteotomies will create a wider initial
gap that may favor the appearance of granulation
tissue without good osteogenic potential.
Latency Period
Latency period is defined as time from surgery to
the beginning of distraction. In an alveolar distraction systematic review from 1996 to 2006, the
most common latency period was 7 days (66%
of the cases reviewed) to allow for healing of the
mucoperiosteum and reduce the risk of wound
DISTRACTION PROTOCOL
After almost 15 years of widespread use, there is
still controversy regarding the best protocol. As
new devices and applications have been designed,
different distraction protocols have been tested
and established. However, the original clinical
Fig. 1. General alveolar distraction timeline.
Alveolar Distraction Osteogenesis: An Update
dehiscence. Extended latency periods of more
than 15 days were applied to ensure complete
revascularization of the transport segment in
cases in which the mucoperiosteal pedicle is small
or endangered.14
the extraosseous distractors, and 18.02 (3.50)
weeks before prosthetic treatment started in
distraction implants.
Distraction Period
Novel alveolar distraction designs are constantly
being developed for research and clinical
purposes. As a general rule they have been classified as intraosseous and extraosseous, depending
on the placement in relation to the bone. In a study
comparing clinical outcomes of intraosseous and
extraosseous alveolar distractors, Uckan and
colleagues,19 found no significant statistical difference despite the higher complication rate and
lower implant success in the intraosseous group.
Devices can also be categorized as unidirectional
and multidirectional, depending on the direction
of the movement. Initial alveolar distractor designs
allowed for only a unidirectional movement,
making correct positioning of the device and
vector control most important. Recent publications have shown the clinical value of multi
directional alveolar distraction devices.6,20,21 A
retrospective study comparing outcomes of unidirectional and bidirectional distractor devices,
Schleier and colleagues21 found no significant
statistical differences in the bone gain or implant
success. Moreover, several cases with unidirectional distraction had to be bone grafted at the
time of implant placement. They concluded that
this difference was caused by the precise control
of the distraction process in the bidirectional
distraction group.
The distraction period encompasses the time
between initial activation and end of the activation
of the distractor device. The amount of distraction
required is generally based on the amount of tissue
necessary to fulfill the implant and dental rehabilitation goals. Several studies have focused on the
amount of alveolar distraction relapse, and their
recommendation is to overcorrect by 20% to
25%.15,16 Apart from the amount of distraction
needed, the distraction rate and rhythm are of
paramount importance during this period.
Distraction rate
The daily amount of bone to be distracted is
known as distraction rate. Saulacic and
colleagues14 reported in a systematic review that
the mean distraction rate was 0.71 (0.27) mm.
They also noted a lower distraction rate of 0.4 to
0.5 mm in cases in which distractor implants and
horizontal distraction were used. According to
Amir and colleagues,17 a distraction rate of 0.5
mm per day results in faster osteogenesis than
a distraction rate of 1 mm in elderly patients.
Distraction rhythm
Distraction rhythm is the number of distraction
activations per day. According to Saulacic and
colleagues,14 the rhythm in alveolar distraction
has tended to be chosen empirically, in part
because of a lack of experimental findings. They
reviewed 209 distractions in 197 patients, and
found that the rhythm of distraction ranged
between 1 (62%), 2 (35%), and 4 times daily (3%).
Consolidation Period
This is the period that allows for maturation and
corticalization of the regenerated bone. According
to Amir and colleagues,9 a minimum of 10 weeks is
required for new bone to bridge a 10 mm alveolar
distraction gap. It has been suggested that the
poorly mineralized bone tissue found after 10
weeks of consolidation will start an adaptive
response that would increase the bone matrix
mineralization with placement of dental implants.18
A systematic review found that the mean consolidation period was 12.22 (5.58) weeks. A difference was noted in the consolidation period when
different distractor devices were used. The mean
consolidation period on intraosseous distractors
was 8.82 (2.67) weeks, 11.44 (2.55) weeks for
ALVEOLAR DISTRACTION DEVICES
INDICATIONS FOR ALVEOLAR DISTRACTION
OSTEOGENESIS
Several clinical indications for alveolar distraction
osteogenesis have been reported in the literature
(Box 1).22–24 Alveolar reconstruction in preparation
for dental implant placement continues to be the
Box 1
General applications for alveolar distraction
osteogenesis
Moderate to severe vertical alveolar bone
defects
Segmental deficiencies of the alveolar ridge
Narrow alveolar ridges
Adjuvant to other bone graft techniques
Gradual vertical movement of ankylosed
teeth
Gradual vertical movement of an osseointegrated
implant
together
with
the
surrounding alveolar bone
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Vega & Bilbao
most common indication (Fig. 2). Reconstruction
efforts have used alveolar distraction as a definitive
procedure to establish the ideal alveolar ridge or
as an adjunctive procedure used to gain bone as
part of a larger reconstruction plan. Overall, alveolar distraction offers several advantages
compared with other augmentation techniques
(Boxes 2 and 3).25
Alveolar distraction has traditionally been used
for vertical augmentation of the alveolar ridge,
but horizontal26–28 and segmental alveolar distraction29,30 have also been described. The main indication for alveolar distraction is to manage the
vertical defects in the anterior maxilla and
mandible. Posterior maxillary defects are best addressed with traditional techniques such as sinus
lift or bone grafts. Vertical defects of the posterior
mandible can be treated with alveolar distraction
but, if the defect also has a horizontal component,
a more traditional approach with an onlay
bone graft or guided tissue regeneration is
recommended.31,32
To facilitate the evaluation and treatment of
vertical alveolar defects, Jensen and Block33
proposed a classification system in which they
defined a class I defect as a mild alveolar vertical
Fig. 2. Alveolar reconstruction using alveolar distraction in preparation for dental implants. (A) Right maxillary
posttraumatic vertical defect. (B) Osteotomy. (C) Alveolar distractor in place. (D) Vector control using a prosthesis.
(E) Panoramic radiograph after the end of the distraction. (F) Placement of dental implants. (G) Panoramic radiograph at the end of the treatment.
Alveolar Distraction Osteogenesis: An Update
Box 2
Advantages of alveolar distraction
osteogenesis for preparation for implant
placement
Simple technique
Simultaneous augmentation of bone and soft
tissues
Less resorption than traditional bone grafts
Transport segment can include teeth or
implants, facilitating the correction of
occlusal or prosthetic defects
Elimination of donor-site morbidity
Shorter treatment times compared with traditional bone grafting techniques
Allows the implementation of complementary techniques when results are not optimal
deficiency with up to 5 mm that ideally can be
treated by a sandwich osteotomy or more traditional bone graft techniques, although distraction
can be considered when there are prosthetic
concerns in the esthetic zone. Class II defects
consist of a moderate vertical loss of 6 to 10 mm
that ideally will benefit from alveolar distraction.
Class III defects are severe vertical losses greater
than 10 mm. Treatment of these defects depends
on the available bone stock. If sufficient bone
exists, distraction can be carried out first, and
definitive alveolar bone form and position can be
performed with a bone graft. If the amount of
bone is not sufficient for distraction, bone
augmentation is carried out first followed by
distraction. Vertical defects that involve adjacent
teeth with significant bone loss are designated as
class IV. In these cases, by extracting the affected
dentition, the defect will be converted into a class
II or III defect, making the problem more predictable and easier to resolve.
and the size and shape of the alveolar defect.
Maxillary and mandibular models with a diagnostic wax-up will allow corroboration of the clinical findings. They can also be used to fabricate
a surgical splint that could be use for vector
control as well as temporary restoration. Models
also play an important role in planning for the
distraction vector, allowing preadaptation of the
device, decreasing surgical time, and identifying
possible device interferences with opposing
dentition. In more complex cases, sterolithographic models are a good option for treatment
planning.
Radiographic examination with plain films or
CT scan is useful for alveolar defect assessment
but it also allows for planning the length and
height of the osteotomy. Of great importance is
the amount of bone stock and its relationship
with the inferior alveolar nerve, inferior border
of the mandible, nasal floor, and maxillary sinus.
These factors could limit device placement or the
distraction procedure. Added consideration
should be given to the prophylactic plating of
the mandible in which the remaining basal bone
is scarce, to prevent fracture and retention of
compromised teeth adjacent to the distractor
procedure and to help with vector control. Newer
technologies,
such
as
computer-assisted
surgical planning, are also being applied to alveolar distraction (Fig. 3).34
ALVEOLAR DISTRACTION: SURGICAL ADVICE
During the different phases of alveolar distraction,
there are a series of considerations that can
contribute to a successful outcome. Allocating
sufficient time for surgical planning is probably
the single most important element in alveolar
distraction.
PLANNING FOR ALVEOLAR DISTRACTION
OSTEOGENESIS
Clinical examination will establish a preliminary
idea of the patient prosthetic needs, occlusion,
Box 3
Disadvantages of alveolar distraction
osteogenesis for preparation for implant
placement
Patient acceptance and compliance
Requires careful vector control
Interference with occlusion might require the
construction of protective appliances
High device cost
Incision
Special consideration should be given to
the location of the incision, because it
will affect the quality of the soft tissue
that will be augmented at the end of
treatment
Use sound surgical principles that will guarantee proper blood supply to the mucosa
and bone
Careful and conservative dissection will
maintain the vascularity of the transport
segment, decreasing excessive resorption
and avoiding damage to adjacent
structures.
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Fig. 3. Alveolar distraction treatment planning using
computer-assisted surgical software.
Osteotomy and Distractor Placement
Use a trapezoidal, semielliptical, or Lshaped osteotomy, depending on location
Lingually convergent osteotomies will
decrease the lingual tipping of the distractor
A piezoelectric-assisted osteotomy will
allow a deeper cut, decreasing the amount
of chiseling required
A transport segment as large as possible
(avoiding compromise of basal bone and
adjacent structures), and not just containing
cortical bone, will avoid a higher rate of
resorption
Newer modular extraosseous distractors
will allow the osteotomy to be performed
after the placement of the device, because
of their ability to remove the distractor rod
Check that the transport segment is able to
move freely through the extension of the
distractor (with the exception of L-shaped
osteotomy)
In cases of large transport segments,
consider the placement of 2 distraction
devices (Fig. 4)
During extraosseous distraction, vector
control can be achieved if the distractor
Fig. 4. Placement of 2 distractors for large transport
segments. (A) Large mandibular defect. (B) Placement
of 2 distractors. (C) Final result after distraction and
implant placement.
plate for the transport bone is cut longer
than usual, allowing movement along the
buccal bone surface.
Distraction Phase
Decreasing the distraction rate and maintaining good oral hygiene will help in the
treatment of wound dehiscence.
Patients should carry a daily log to record
the amount of daily activations.
Monitor the distraction vector carefully.
Several methods for vector control have
been described,35–38 and these are illustrated in Fig. 5 and Box 4.
Alveolar Distraction Osteogenesis: An Update
Fig. 5. Vector control. (A) Mandibular vertical defect with severe bone loss involving second molar. (B) Osteotomy. (C) Placement of intraosseous distractor. (D, E) Vector control using orthodontic elastics and compromised
tooth. (F) Final result after distraction, extraction of second mandibular molar, and placement of 2 implants.
When a prosthesis is used as vector control,
it must be adjusted daily.
Always consider overcorrection.
Consolidation Phase
Covering the distractor rod with a red
Robinson catheter will avoid excessive
trauma to the surrounding soft tissues
Box 4
Methods for vector control in alveolar
distraction osteogenesis
Device modifications
Orthodontic mechanics: elastic traction, wire
stabilization
Modified prosthesis
Manual manipulation of the regenerated
bone
Osteotomy after distraction completed
Avoid excessive pressure on transport
segment when using a temporary
prosthesis
In selected cases, implant placement
during the consolidation phase will allow
for stability of the regenerated bone and
maintenance of the distraction vector.
Implant Placement
Thoroughly clean the granulation tissue in
the area where an intraosseous distractor
has been placed. Avoid placement of
implants in this area but, if necessary, use
a large-diameter implant
When possible, use long implants that
will engage the native bone. Implant
planning software is helpful in this treatment stage
To avoid further resorption, do not delay
implant loading more than traditional
implant protocols.
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CLINICAL OUTCOMES IN ALVEOLAR
DISTRACTION OSTEOGENESIS
Vertical Bone Gain
Data of 181 patients from a recent review by
Chiapasco and colleagues39 showed that the
amount of bone gain after distraction osteogenesis had a range of 3 to 20 mm. Saulacic and
colleagues14 reported in their systematic review
the mean bone gain obtained by different types
of distractors: distraction implants, 5.02 (0.09)
mm; intraosseous distractors, 7.86 (0.36) mm;
and extraosseous distractors, 9.31 (0.45) mm.
A clinical assessment of 40 patients subjected
to an extraosseous distraction showed that the
bone augmentation average was 9.5 mm in
height, showing a 92.5% success rate.40 Kanno
and colleagues16 reported comparable results
on bone gain using extraosseous distractors;
they also noted that, during the consolidation
period, there was 15% to 25% bone height
reduction. These findings are similar to the
previous reports in the literature that recommend
20% to 25% overcorrection in vertical alveolar
distraction.15,41,42 Perdijk and colleagues43
pointed out the influence of vector of distraction
on vertical gain. They studied 34 cases of alveolar
distraction on atrophic mandible in which nearly
all patients had lingual tipping of the segment by
a mean of 12 . This finding meant that, in those
cases, only 87% of maximum vertical bone gain
could be achieved.
Alveolar Distraction Compared with
Conventional Bone Grafting Techniques
In 2004, Chiapasco and colleagues44 compared
alveolar distraction osteogenesis with guided
bone regeneration on vertically deficient alveolar
ridges. This prospective study evaluated parameters such as bone resorption of the regenerated
ridges before and after implant placement,
peri-implant bone loss at 1, 2, and 3 years after
prosthetic loading of the implant, and success
rates of implants. The results suggested that
alveolar distraction might offer more predictable
long-term results for bone gain maintenance and
peri-implant bone resorption. Furthermore,
implant success rates were significantly higher in
the alveolar distraction group. Chiapasco and
colleagues45 also compared alveolar osteogenesis with autogenous onlay bone grafts using the
similar parameters. This study found that bone
resorption before implant placement was significantly higher in the autogenous onlay bone graft
group. For implant success, no difference was
encountered between the groups. Uckan and
colleagues46 also compared alveolar distraction
with autogenous onlay graft using complication
and implant survival rates. Their results showed
a higher complication rate with the alveolar
distraction (66.8% vs 33.8%). But they also
reported that those complications were minor
and easier to treat than those of the autogenous
onlay graft. Again, implant survival rates were
similar between the groups (91.4% alveolar
distraction vs 93.7% autogenous onlay graft). In
a prospective study comparing alveolar distraction
with inlay bone grafting in the posterior mandible,
Bianchi and colleagues47 showed that, although
the mean bone gain with alveolar distraction was
significantly better (10 mm vs 5.8 mm), the complication rate was significantly higher in the alveolar
distraction group (60%) than in the inlay bone graft
group (14.3%).
Two literature reviews of bone augmentation
procedures on edentulous ridges for dental
implants concluded that it is difficult to demonstrate that one surgical procedure offered better
outcomes than another because of the poor methodological quality of the articles published
(Table 1).39,48 Their recommendation is to give
Table 1
Comparison of augmentation techniques on edentulous ridges for dental implant placement
Technique
Success Rate (%)
Implant Survival (%)
Guided bone regeneration
Onlay bone grafts
Split ridge
Alveolar distraction
Microvascular flaps
60–100
92–100
98–100
96.7–100
87.5
92–100
60–100
91–97.3
90.4–100
88.2
Data from Chiapasco M, Zaniboni M, Boisco M. Augmentation procedures for the rehabilitation of deficient edentulous
ridges with oral implants. Clin Oral Implants Res 2006;17(Suppl 2):136–59.
Alveolar Distraction Osteogenesis: An Update
priority to those procedures that are simpler, less
invasive, involve less risk of complications, and
reach their goals in the shortest time.
Alveolar Distraction on a Previously
Reconstructed Site
Reconstruction of severe maxillary and mandibular defects for dental implants after trauma or
tumor ablation is often a difficult task. Case reports
in the literature describe the use of alveolar
distraction as adjuvant to enhance sites previously
reconstructed with iliac bone grafts,49,50 scapula
free flaps,51,52 and fibular free flaps.53,54
In a retrospective study, Kunkel and colleagues50
reported on 4 patients who underwent iliac crest
bone graft for mandibular reconstruction after
tumor ablation and later alveolar distraction with
an intraosseous device. The vertical gain range
was from 5 to 9 mm and, of the 12 implants placed,
1 failed and 1 had critical bone loss after 40 months
of follow-up. Hirota and colleagues51,52 described
the use alveolar distraction to enhance the mandibular reconstruction carried out with free scapula
flaps in 2 patients. They reported vertical gains of
9 and 10 mm and placement of 9 implants with
a 100% success rate after 2 years of follow-up. In
2009, Lizio and colleagues54 used alveolar distraction to increase the vertical bone height on
6 patients after reconstruction with free fibula flaps.
The mean vertical bone gain was 14 mm (12–15 mm).
They placed 35 implants, 4 of which failed during the
follow-up period, bringing the cumulative implant
survival to 89%. They also reported 1 case with
fracture of the remaining basal fibula during
consolidation.
Success of Dental Implants
in Distracted Bone
Prosthetic rehabilitation facilitated by the placement of dental implants is the ultimate goal of
alveolar distraction. Controversy still remains
regarding the best time for implant placement.
A prospective multicenter study reported the
outcomes of 138 implants placed in distracted
bone after 2 or 3 months of consolidation. After
a mean follow-up of 34 months after prosthetic
loading, the success rate was 94.2% with a cumulative survival rate of 100%. No statistically significant differences were found between the different
centers.55
Using 92 distractor implants on 46 patients with
severely atrophic mandibles, Raghoebar and
colleagues56 reported a survival rate of 97% after
a minimum of 62 months of follow-up. In a retrospective study, Elo and colleagues57 compared
the implant success rates in distracted bone with
autogenous bone-grafted sites. They placed 184
implants on 65 patients reconstructed with autogenous bone, with an implant success rate of 97%.
The distraction group contained 56 implants on 17
patients and a success rate of 98%. Again, no
statistical difference was noted between groups.
A systematic review on alveolar distraction
analyzed a total of 469 implants placed in
distracted bone. The mean osseointegration
period was 4.59 (1.34) months. The overall
survival rate was 97%. They reported 14 implant
failures, 10 of them before loading. The mean
follow-up was 14.19 (11.03) months. This analysis also found no significant difference in implant
failure rate associated with location, indication
for distraction, latency period, and daily rate and
rhythm.
The
mean
augmentation
rates
approached a statistically significant difference:
rate on successful implants was 6.79 (2.51) mm
and 8.40 (2.31) mm on failed implants. A significant difference was encountered in the relationship between implant failures and distraction
implants. Consolidation period also showed significant differences; failed implants were placed after
8.10 (2.51) weeks, compared with 12.43 (5.62)
weeks for successful implants. Peri-implant bone
level was reported for 301 implants. Stable periimplant bone level was maintained in 285 (95%)
of the implants.14 Recent studies reported periimplant bone loss values of 0.89 to 1.9 mm/y in
areas of alveolar bone distraction.42,58
Immediate Loading of Implants
on Distracted Bone
In 2004, Degidi and colleagues59 presented a case
of immediate loading of implants placed in
distracted bone. Although this practice has not
been popular, a study was carried out comparing
data from radiofrequency analysis on implants
placed in native bone and distracted bone. Even
when the results were significantly inferior for
implants placed in distracted bone, the investigators concluded that the values obtained suggest
the possibility of immediate loading with outcomes
similar to those of implants in native bone.60
Adjunctive Techniques to Improve the
Outcomes of Alveolar Distraction
Research is being conducted on ways to improve
the outcome of alveolar distraction. Robiony and
colleagues61 reported on their long-term experience with 12 patients after alveolar distraction
and a combination of autologous bone graft with
platelet-rich plasma on severely atrophic mandibles. After performing an osteotomy, the distractor
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Vega & Bilbao
Table 2
Complications of alveolar distraction, possible causes, management and prevention
Phase
Complication
Causes
Management
Prevention
Intraoperative
Inability to mobilize the
transport segment
Incomplete osteotomy
Poor osteotomy design
with lack of divergence
Lack of sufficient bone
stock
Excessive force during
mobilization of the
osteotomy
Retrace osteotomy
Better execution and
planning of the osteotomy
Small fractures: removal
of fragment, relocate
distractor arms to new
position (extraosseous
devices) (Fig. 6)
Large fractures: suspension of
distraction procedure,
osteosynthesis, possible
bone graft (Fig. 7)
Reduction and fixation
of fracture segments
Cautious osteotomy and
mobilization of the
transport segment
Shortening or reposition
of distractor rod
Conservative
Careful planning using cast
models
Careful planning and
execution of osteotomy
Use cast models to prebend
device avoiding excessive
manipulation
Fracture of the transport
segment
Fracture of the basal bone
Occlusal interference
of distractor rod
Damage to adjacent
structures
Distractor fracture
(extraosseous devices)
Lack of sufficient bone
stock
Excessive force during
mobilization of the
osteotomy
Lack of proper planification
Improper surgical
technique
Excessive bending of
distractor arms
Change distractor device
Careful planification and
execution of osteotomy
During distraction and
consolidation
Wound dehiscence
Mucosa perforation
Premature consolidation
Distractor failure
Incorrect distraction vector
Transport bone resorption
Bone defect
Reduction distraction rate,
secondary suture
Trimming sharp edge
Repeat osteotomy
Distractor removal
Consider distractor
replacement or bone
grafting procedure (Fig. 8)
Vector control (see Table 1)
Smaller distraction rate
Smoothing alveolar ridge
irregularities
Correct patient selection and
patient education
Decrease latency period
Increase distraction rate
Avoid excessive manipulation
of devices
Careful planning, close
monitoring
Consider overcorrection
Conservative
Consider bone grafting
Good alveolar distraction
technique
Alveolar Distraction Osteogenesis: An Update
After distraction
Excessive tension at closure
Poor soft-tissue coverage
Sharp bony edges in the
transport segment
Lack of compliance of the
patient
Excessive latency period
Slow distraction rate
Loosening due to poor
bone quality on the
transport segment
Distractor fracture
Excessive pull from lingual
and palatal periosteum,
muscle insertions
Incorrect placement of the
distractor
Interruption of blood
supply due to excessive
reflection of perforation
of tissue
Multifactorial
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Vega & Bilbao
Fig. 6. Small fracture of transport segment treated by
repositioning the distractor device.
was activated for 2 to 3 mm and the gap was filled
with the combination of iliac crest bone graft and
platelet-rich plasma. Their results showed
a vertical bone gain that range from 7 to 10 mm
with 1 failed case due to scar retraction. The
mean decrease of total bone volume was 2.3%
at the time of implant placement. A total of 47
implants were placed, and bone loss after 1 year
of loading was 0.61 mm and 1.51 mm after 5 years.
The implant survival and success rates were
97.9% and 91.5%. A double-blinded trial investigated whether low-intensity pulsed ultrasound
therapy stimulates osteogenesis in mandibular
Fig. 7. (A, B) Panoramic radiographs showing large
fracture of transport segment that required the
suspension of the procedure.
alveolar distraction. Biopsies taken at implant
placement after 46 8.1 days of consolidation
underwent histologic and microradiographic
examination. The investigators concluded that
ultrasound treatment does not seem to stimulate
bone formation.62 Dergin and colleagues63
reported a case using a novel technique whereby
alveolar distraction was done incorporating a polytetrafloroethylene membrane for protection of the
distraction chamber. No defects were noted in
the 10 mm of newly regenerated bone. Further
research is necessary to validate this technique.
At the time of this writing, no human studies using
bone morphogenic proteins and alveolar distraction have been published in the English literature.
Patient Perception and Satisfaction After
Alveolar Distraction
Even when objective clinical data suggest good
results, ultimately it is patient satisfaction that
leads to the success of a treatment plan. Using
a distractor implant on 46 patients, Raghoebar
and colleagues56 reported patient satisfaction of
8.1 (1.2) (0 5 completely dissatisfied; 10 5
completely satisfied) after finalization of the prosthetic treatment. Allais and colleagues64 used
extraosseous devices in 50 patients to evaluate
the patients’ perceptions during and after alveolar
distraction. Their findings showed that, in 76% of
the cases, the patient reported the surgery as
good and bearable (all patients were orally
sedated with 15 mg of midazolam). During distraction, 4% of the patients felt pain, 46% had some
difficulty activating the device, and 10% needed
extra help. The activation rod was a cause of
complaint in 52%. Of the 50 patients, 27 had to
undergo additional autologous bone grafting, and
70% of them stated that the bone grafting procedure was more painful than the alveolar distraction. Seventy-eight percent of the patients
treated with alveolar distraction would undergo
this procedure again if necessary. In a more recent
study from the French literature, Castry and
colleagues65 analyzed the answers of 23 patients
after alveolar distraction. They found that 87% of
the patients adjusted well to the procedure. Light
to moderate pain was reported by 57%, and
43% of the patients cataloged the procedure as
painful. Fifty-seven percent of the patients
managed to forget the presence of the distractor,
and 65% had no problem with the length of the
treatment. Approximately 91% of the patients
were able to activate the distractor device on their
own, and 52% of the patients reported that they
would undergo another distraction procedure if
necessary.
Alveolar Distraction Osteogenesis: An Update
Fig. 8. Fracture of alveolar distractor device treated with bone graft procedure. (A) Right mandibular vertical
defect. (B) Osteotomy. (C, D) Panoramic radiograph and clinical picture showing fracture of the alveolar distraction device. (E) Distraction gap after removal of device. (F) Stabilization of transport segment with miniplates.
(G, H) Bone graft and membrane in place. (I) Radiograph showing vertical bone augmentation.
381
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Complication Rates of Alveolar Distraction
Despite almost 15 years of clinical practice,
growing popularity, and newer technologies, alveolar distraction continues to be a challenging
procedure. Alveolar distraction complications
have conventionally been classified according to
the distraction phases in which they occurred:
intraoperative, during distraction, during consolidation, and after distraction. They can also be
classified as minor complications or major complications that are more difficult to manage and could
jeopardize the distraction procedure. In addition to
the common complications of any surgical procedure, such as excessive bleeding, hematoma,
infection, and paresthesia, there is a set of specific
complications for alveolar distraction. These
complications, the possible causes, management,
and prevention are listed in Table 2.
In more recent years, several articles have focus
on the complications of alveolar distraction. These
studies have reported a wide array of complication
rates, ranging from 36% to 100%.41,42,66–70 In
a comprehensive review of the literature from
1996 to 2008, Saulacic and colleagues71 studied
the complication rate of alveolar distraction. Their
results showed an overall complication rate of
30%. The most common complication was insufficient bone formation after the consolidation period
(8%), followed by regression of distraction
distance (7%), and problems related to the device
(6%). Intraoperative complications include
bleeding from the floor of the mouth (4%) and
temporary paresthesia (4%). During the distraction
period, wound dehiscence was found on 1% of the
patients. Pain was reported in 1% of the patients,
as well as mild soft-tissue resistance. Vector deviation was found in 2%. More severe complications
were found during the consolidation period,
including a mandibular fracture rate of 2% and
problems related to the device in 6% of the cases.
They also found that insufficient bone formation
and evidence of complications were significantly
related to the type of distractor and augmentation
rates greater than 0.5 mm daily. The investigators
concluded that, although complications in alveolar
distraction are frequent, they rarely cause severe
problems. They suggested that most of the
complications could be related to lack of experience and the learning process.
SUMMARY
Alveolar distraction is a technique in constant
evolution. A review of the literature within the
past 14 years reveal that there are clear indications
for its use, with outcomes similar to and
sometimes even more predictable than traditional
bone grafting techniques in preparation for implant
placement. Although complications exist with
alveolar distraction, it seems that most are minor
and easy to manage. Appropriate patient selection
and a better understanding of the technique are
paramount in successful bone regeneration with
alveolar distraction osteogenesis.
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