Distraction osteogenesis /certified fixed orthodontic courses by Indian dental academy

Craniofacial Distraction
Osteogenesis

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Craniofacial Distraction
Osteogenesis


Introduction




Distraction Osteogenesis is a biological process
of new bone formation between the surfaces of
osteomized bone segments that are seperated
gradually by incremental traction.
According to Aranson ‘ Distraction
Osteogenesis is mechanically induced,
intramembranous ossification between two
living bone surfaces acutely seperated by low
energy techniques, undergoing gradual
seperation.

Origin and Evolution


Dentofacial Traction. Wescott first reported the
placement of mechanical forces on the bones of
the maxilla in 1859. He used two double clasps
seperated by a telescopic bar to correct a
crossbite in a 15 yr old girl. A year later, Angell
performed a similar procedure with a
differentially threaded jackscrew connected to
the premolars.

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Goddard, in 1893 further standardized the
palatal expansion protocol, he activated the
appliance twice a day for 3 wks followed by a
stabilization period to allow the deposition of
‘Osseous material’ in the created gap.
In 1905, Codvilla reported the first bone distraction
for the treatment of shortened femur.


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In 1927, Abbot reported lengthening of tibia.
In 1927, Rosenthal reported first mandibular
osteodistraction procedure by using an intraoral
tooth-borne appliance.
In 1937, Kazanjian reported mandibular
osteodistraction using a gradual incremental
traction.


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

In 1948, Crawford applied gradual incremental
traction to the fracture callus of the mandible.
In 1954, Ilizarov introduced his distraction
osteogenesis technique for limb lengthening.
The procedure was initiated by surgical bone
division with maximum preservation of
periosteum and endosteum- a technique that he
called corticotomy.

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The first report demonstrating the application of
Ilizarov principles to mandible appeared in 1973 by
Snyder et al.
In 1976, Michieli and Miotti demonstrated the
feasibility of intraoral mandibular lengthening.
In 1989, McCarthy et al were the first to apply the
technique of Extraoral osteodistraction on 4
children with congenital craniofacial anomalies.


Classification of Distraction Device




External (Bone-Borne): Unidirectional,
Bidirectional and Multidirectional devices.
Internal (Subcutaneous or Intraoral): Intraoral
Devices can be placed Extramucosal or
Submucosal. These devices can be Bone-borne,
tooth-borne or Hybrid.


Biological basis of new bone formation




Distraction osteogenesis begins with the
development of a reparative callus between the
surfaces of two bone segments surgically divided
by a low energy osteotomy.
After the callus has formed initially, a traction
force is applied to these bone segments, which
gradually pushes them apart.


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Gradual incremental seperation of bone
segments places the callus under tensional stress
that aligns the newly formed intersegmentary
tissues parallel to the direction of traction.
After the desired amount of lengthening is
achieved, the distraction force is discontinued
and the newly formed bone (distraction
regenerate) undergoes maturation and
remodeling until it becomes indistinguishable
from the residual bone.

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1.
2.
3.
4.
5.

Clinically, distraction osteogenesis consists of
five sequential stages:
Osteotomy
Latency
Distraction
Consolidation
Remodeling

Osteotomy. Discontinuity of a skeletal segment
(also referred to as fracture) triggers an
evolutionary process of bone repair similar to
that observed during fracture healing.
 Fracture healing has six sequential phases:
1) Impact 2) Induction 3) Inflammation 4)Soft
callus 5) Hard callus 6) Remodeling





Latency. The latency is the period from bone
division to the onset of traction. Latency
represents the time allowed for reparative callus
formation.
The stage of inflammation lasts from 1 to 3 days,
at which time the bone segments are surrounded
by granulation tissue consisting of inflammatory
cells, fibroblasts, collagen and invading
capillaries.

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During the following stage of soft callus that
lasts about 3 wks , capillaries continue to grow
into the fracture callus ; at this time the
granulation and loose connective tissue are
converted gradually to fibrous and cartilaginous
tissue.


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

Distraction. During the normal fracture healing, the
stage of soft callus is followed by the stage of hard
callus, which typically lasts 3 to 4 months.
During this period , the fibrous and cartilaginous tissues
of soft callus are transformed into woven bone by
osteoblasts. This period is followed by the final stage of
remodeling, when woven bone is remodeled slowly to
lamellar bone with gradual reconstitution of the
medullary canal.


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

During distraction, however, the normal process
of fracture healing is interrupted by the
application of gradual traction to the bone
segments at the stage of soft callus.
This traction progressively seperates the bone
segments, thereby generating tensional stress in
the tissues of the forming soft callus and in the
surrounding soft tissues.


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Ilizarov summarized the tension stress effect in
the folowing statement: “ Gradual traction of
living tissues creates stress that stimulates and
maintains regeneration and active growth of
these tissues”.
In the forming soft callus tissues, tension stress
creates a dynamic microenvironment and
produces several specific changes that can be
considered as a growth-stimulating effect and a
shape-forming effect.

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According to Ilizarov, the growth-stimulating
effect of tension activates the biologic elements
of the stretched soft callus tissues resulting in
increased proliferation of the fibroblastic cell
population and prolongation of angiogenesis
with tissue oxygenation.
The shape-forming effect of tension alters the
phenotypic expression of the ‘distraction’
fibroblasts, which appears as spindle shaped
fibroblast like cells with hypertrophic
intermediate filaments.

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As a result, the fibrous tissue of the soft callus
becomes longitudinally oriented in a direction
parallel to the axis of distraction.
Consolidation The consolidation period is the
period between cessation of traction forces and
removal of the distraction device.
This period represents the time required for
complete mineralization of distraction
regenerate.

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After distraction ceases, bone trabeculae
continue to grow at the center of the regenerate
towards each other until they overlap and fuse.
The fibrous interzone gradually ossifies, and one
distinct zone of woven bone completely bridges
the gap, indicating a disappearance of soft callus
stage.
Although the distraction regenerate forms
predominantly by intramembranous ossification,
isolated islands of cartilage are often observed.

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Remodeling The remodeling period is the period from
removal the distraction device to the application of the
full functional loading to the bone segment that
contains the distraction regenerate.
During this period, the zone of primary trabeculae in
the center of the regenerate significantly decreases and
later is resorbed completely. As the regenerate matures,
the initially formed bony scaffold is reinforced by
parallel fibrered and lamellar bone.


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The cortical bone and marrow cavity are
restored. Haversian remodeling, representing the
last stage of cortical reconstruction, normalizes
the bone structure.
Usually, the process takes a year before the
structure of newly formed bony tissue is
comparable to that of the preexisting bone.


Biomechanical Considerations


1)
2)
3)

The biomechanical parameters of
osteodistraction can be divided into several
categories:
Extrinsic or fixator related factors
Intrinsic or tissue related factors
Factors related to device orientation


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Extrinsic parameters affect the mechanical
integrity of the distraction device, which in turn
influences the stability of bone fixation.
Intrinsic parameters affect the quality of the
forming distraction regenerate.




Another critically important biomechanical
parameter of distraction osteogenesis is the
orientation of the distraction device and the
resulting distraction vector relative to the
anatomic axis of the bone segments, occlusal
plane and desired direction of distraction.


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Transverse Dimensions
Samchuko et al 1998(JOMFS) demonstrated that
bilateral lengthening of the mandibular corpus
with linear distractors attached parallel to the
lateral surface of the mandible caused an
increased intercondylar width during distraction.
Because of limited lateral mobility of the
condyles and rigid fixation of distraction devices
to the body of the mandible, the tendency
towards lateralization of proximal segments may
generate unfavorable reactive forces.

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When the devices were placed parallel to the
direction, however, the lateral forces and the
tensile and compressive strains were minimized
significantly.
Because device orientation causes an alteration
in bony force level and strain patterns, it also has
the potential to affect the quality and quantity of
the regenerate tissue.



It follows that devices oriented parallel to the
body of the mandible may increase lateral forces
at the proximal segment and introduce
compressive strains within the regenerate tissue,
possibly inhibiting osteogenesis.


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Incremental midline mandibular widening
demonstrated a gradual increase in intercondylar
angle because of transverse rotation of both
condyles.
When the distractors were oriented parallel to
the mandibular body (Model III) the
intercondylar width increased incrementally.


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the direction of distraction (Model IV) the
intercondylar width was maintained at all
increments of lengthening.
The condylar rotation seen during midline
widening, if not compensated, can create
inappropriate loading on the articular surface of
the condyles, potentially causing degenerative
changes.

Sagittal Plane



The effects were demonstrated by Samchukov
1999.
A simulated osteotomy of the mandibular
corpus was performed posterior to the third
molars bilaterally and linear distractors were
oriented parallel to the inferior border of the
mandible in Model V. In Model VI the
distractors were oriented parallel to the occlusal
plane.

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Mandibular lengthening with the linear
distractors attached parallel to the inferior
border of the mandible increased the distance
between maxillary and mandibular occlusal
planes resulting in an increased lower anterior
facial height.
the maxillary occlusal plane, no changes in
LAFH occurred during the 10mm of mandibular
lengthening.

Soft tissue Adaptation




Lengthening of the soft tissues is an important
part of the distraction process. Bone lengthening
is possible because the bone is surgically divided
into multiple segments where as soft tissues are
stretched without any surgical procedure.
Because of this, different biological mechanisms
are involved in the soft tissue response to
gradual stretching. This biologic process is
termed ‘Distraction Histiogenesis’

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1)

2)

Two predominant mechanisms of soft tissue
adaptation occur during distraction
histiogenesis:
Soft tissue regeneration following disruptive
and degenerative changes
Neohistiogenesis as a result of generalized
cellular proliferation and growth.


Dental/PDL Distraction


Orthodontic tooth movement is a process in
which a mechanical force is applied to induce
alveolar bone resorption on the pressure side,
and alveolar bone deposition on the tension
side. On the tension side, the periodontal
ligament is stretched (distracted) followed by
alveolar bone deposition (osteogenesis). The
periodontal ligament is a “suture” between
alveolar bone and tooth.



The process of osteogenesis in the periodontal
ligament during orthodontic tooth movement is
similar to that in the midpalatal suture during
rapid palatal expansion, or to that in the midface
sutures in the growing animal during midface
distraction. The major difference is the rate of
osteogenesis.


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The regular rate of osteogenesis in orthodontic
tooth movement during canine retraction is
about 1 mm per month, which is much slower
than that in distraction osteogenesis. However, it
has been shown that by orthodontically moving
a tooth into the fibrous bone tissue just created
by distraction osteogenesis in a canine model,
the rate of the orthodontic tooth movement
could be as much as 1.2 mm per week in the
mandible. (Liou et al 1998)

Technique of Dental distraction
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

Liou and Huang 1998 AJODO
Right after the first premolar extraction, the
interseptal bone distal to the canine is
undermined with a bone bur, grooving vertically
inside the extraction socket, along the buccal
and lingual sides, and extending obliquely
toward the base of the interseptal bone to
weaken its resistance. The interseptal bone is not
cut through mesiodistally toward the canine.

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The depth of the undermining grooves is
dependent on the thickness of the interseptal
bone, as revealed on the periapical films.
A custom-made intraoral distraction device is
delivered for canine distraction right after the
first premolar extraction. It is activated 0.5 to 1
mm/day right after the extraction until the
canine is distracted into the desired position and
amount.



Liou and Huang (1998) reported that both the upper
and lower canines were distracted bodily 6.5 mm into
the extraction space within 3 weeks. New alveolar bone
was generated and remodeled rapidly in the mesial
periodontal ligament of the canine during and after the
distraction. It became mature and indistinguishable
from the native alveolar bone 3 months after
distraction. During the distraction, 73% of the first
molars did not move mesially and 27% of them moved
less than 0.5 mm mesially within 3 weeks.



The radiographic examination revealed that
apical or lateral surface root resorption of the
canine was minimal. No periodontal defect or
endodontic lesion was observed throughout and
after distraction. It was concluded that the
periodontal ligament could be rapidly distracted
without complications.



The radiographic changes of the periodontal
ligaments on the mesial side of the canines could
be classified into five stages, from the initiation
of the distraction to the complete remodeling of
the new alveolar bone:


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Stage 1. Stretching and widening of the
periodontal ligament. This was in the first week
after initiating the distraction. Bone formation is
not evident in this stage.
Stage 2. Active growing of striated bone (new
bone spicules) in the distracted periodontal
ligament. This occurred during the second week
after the initiation to the end of distraction.
Striated bone was growing actively in the
distracted periodontal ligament.

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Stage 3. Recovery of the distracted periodontal
ligament. This occurred in the first to fourth
week after completing the distraction. The
striated bone became denser, gradually
extending from the distal lamina dura (native
lamina dura) of the interseptal bone, distal to the
lateral incisor, toward the canine. The distracted
periodontal ligament gradually decreased in
width and back to normal. The radiographic
characteristics of the striated bone created by the
distraction were similar to a cortical bone or
thickened lamina dura.

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Stage 4. Remodeling of the striated bone occurs
from the fourth week to the third month after
completing the distraction. The striated bone
has gradually decreasing radiodensity, initiating
from the native lamina dura toward the canine.
It eventually would become the new lamina dura
on the mesial side of the canine. The
radiodensity of the remodeling striated bone is
similar to the cancellous alveolar bone. The
native lamina dura disappears gradually.

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Stage 5. Maturation of the striated bone takes 3
months after completing the distraction. The
native lamina dura disappears and the new
lamina dura is of normal thickness. On the
radiographs, the interseptal bone between the
lateral incisor and the canine is indistinguishable
from the other interseptal bones.


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Why is the mesial movement of the first molar
minimal? After the initial tooth movement by a
light or heavy orthodontic force, a lag period of
minimal tooth movement persists for
approximately 2 to 3 weeks before tooth
movement again proceeds.
The canine distraction is completed with the
first molar still in its lag period or just initiating
its mesial movement.

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The periodontal ligament is essentially a
hydrostatic system maintained by blood pressure
of the capillary bed. A force in excess of 26
g/cm2 was estimated to strangulate the
periodontal tissues, forcing the tooth into
physical contact with the alveolar bone and
causing necrosis. The initial obstacle to
orthodontic tooth movement is the necessary
elimination of the necrotic (hyalinizing) tissues
by undermining resorption. The elimination of
the hyalinizing tissues takes 2 to 3 weeks, which
is the lag period.

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Any technique that takes longer than 3 weeks to
retract a canine will result in loss of anchorage.
Because not only the canine but also the anchor
unit will move to each other after the lag period.
The average time of a canine retraction takes 4
to 6 months according to the anchorage needs.
However, the anchor unit also will move
forward accordingly (loss of anchorage). The
best way to avoid losing anchorage is to move
the canine before the anchor unit moves.

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Why is the root resorption minimal? External
root resorption is initiated 2 to 3 weeks after the
orthodontic force is applied and may continue
for the duration of force application. In this
technique, the canine distraction is completed
within 3 weeks before the root resorption could
initiate.

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An association between the increased root
resorption and the duration of the applied force
has been reported. The duration of the applied
force is an aggravating factor for the root
resorption, and it is regarded as a more critical
factor than the magnitude of the force, especially
in connection with long treatment periods.




The best way to minimize the root resorption
induced by orthodontic tooth movement is to
complete the tooth movement in a short
duration or even before initiation of root
resorption.


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Why can the canine be distracted so fast while
the first molar was still in the lag period? The
orthodontic tooth movement is faster and root
surface resorption is less in an alveolar bone
with loose bone trabeculae and less bone
resistance. In this technique, the canine is
distracted into an extraction socket that has not
been refilled by solid bone tissue.

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After tooth extraction, regenerative bone tissue
will refill the extraction socket in 3 weeks and
become resistant and solid in 3 months. If the
canine is not retracted across the first premolar
extraction socket in the first 3 weeks, the rate of
tooth movement will slow down, root surface
resorption will increase, and the anchor unit will
start to move forward.

Dentoalveolar Distraction
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

First reported by Haluk Iseri and Reha Kisnisci
(JOMFS 2002)
A horizontal incision is made parallel to the
gingival margin of the canine and the bicuspid
beyond the depth of the vestibule. Flap elevation
is done so that canine root is visualized properly.
With a round carbide bur buccal cortical holes
are made both mesial and distal to canine and
are continued 2 to 3 mm beyond the apex of the
canine.



The holes are then connected with a straight
fissure bur. Fine vertical and horizontal
osteotomies are performed with curved and
straight osteotomes to make canine a bone
transport segment. The transport dentoalveolar
segment includes the buccal cortex and the
underlying spongy bone. The wound is
thoroughly irrigated with saline and sutured. The
device is fitted and cemented to canine and
molar.

Modified Dentoalveolar Distraction
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

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Yadav, Patil, Keluskar JIOS 2005
After making canine as a bone transport
segment, similar buccal cortical holes are made
mesial and distal to first premolar and apically
continued to the same depth as that of canine.
The holes are connected with a straight fissure
bur and premolar is extracted so the buccal
cortical plate comes along with the extracted
premolar.

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Advantages of modification
Buccal cortical plate comes along with the
extracted premolar.
Time saving as cortical plate need not be
trimmed.
Less chance of injuring the maxillary sinus
lining.


Distraction Protocol




In periodontal distraction, canine is distracted
immediately after the surgical procedure 0.35
mm turns twice daily. (Liou and Huang 1998
AJODO)
In a recent study of periodontal distraction by
Sayin etal (Angle Orthod 2005) canine was
distracted immediately after the surgical
procedure 0.25 mm per turn thrice a day.

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In dentoalveolar distraction , canine is distracted
same day at a rate of 0.4mm per turn twice a
day.( Haluk Iseri et al (2002 JOMFS)
In a recent study same authors mentioned that
they start distraction within 3 rd day of the
surgical procedure. (Iseri AJODO 2005)




In periodontal ligament distraction , the total
time required was 21 days where as in
dentoalveolar distraction a mean of 10 days( 8 to
14 days).


Mandibular Alveolar Distraction Osteogenesis


Maxillary Alveolar Distraction Osteogenesis


Mandibular Distraction


Maxillary Distraction with RED


Surgically Assisted RME


Soft tissue to hard tissue advancement ratios for
mandibular elongation using distraction osteogenesis
in children.


Melugin Angle Orthod. 2006



Distraction osteogenesis is extensively used for
the elongation of hypoplastic mandibles in
children, yet the soft tissue profile response to
this is not well understood.




The pre- and posttreatment lateral
cephalometric radiographs of 27 pediatric
patients who underwent bilateral mandibular
elongation using distraction osteogenesis were
analyzed retrospectively to correlate horizontal
soft tissue advancement with horizontal
underlying bone advancement at B point and
pogonion.



Horizontal advancement (in millimeters) of
bone and overlying soft tissue at these points
was collected from the radiographs of each
patient, and linear regression analysis was
performed to determine the relationship of hard
to soft tissue horizontal advancement at these
points.




A 1:0.90 mean ratio of bone to soft tissue
advancement was observed at B
point/labiomental sulcus and at pogonion/soft
tissue pogonion. These ratios were consistent
throughout the sample population and are highly
predictive of the soft tissue response that can be
anticipated.




Magnitude of advancement, age, and sex of the
patient had no effect on these ratios in selected
population. This study assists with our
understanding of the soft tissue response that
accompanies bony elongation during distraction
osteogenesis which will allow us to more
effectively treatment plan the orthodontic and
surgical intervention that will optimize the
patients' functional and esthetic outcome.

A meta-analysis of cleft maxillary osteotomy and
distraction osteogenesis.


Cheung, Chua Int J Oral Maxillofac Surg. 2006



A PUBMED search of the National Library of
Medicine from 1966 to December 2003 was
conducted. Keywords used in the search were
'cleft', 'distraction', 'maxilla', 'maxillary',
'advancement', 'osteotomy', and 'orthognathic
surgery'. This study concluded that distraction
osteogenesis tends to be preferred to
conventional osteotomy for younger CLP
patients with more severe deformities.



In such cases it was feasible to use distraction to
correct moderate to large movement of the
maxilla by either complete or incomplete Le
Fort I osteotomy, and a concurrent mandibular
osteotomy was less frequently required. Intraoperative and post-operative complications were
uncommon with either technique, and some of
the traditional ischemic complications related to
conventional osteotomy were replaced by
infection of the oral mucosa due to the
prolonged retention of the distractors.



There is still no conclusive data on any
differences in surgical relapse, velopharyngeal
function and speech between the two
techniques. The authors concluded that both
distraction osteogenesis and conventional
osteotomy can deliver a marked improvement in
facial aesthetics.


Sutural distraction osteogenesis (SDO) versus
osteotomy distraction osteogenesis (ODO) for
midfacial advancement


Liu et al J Craniofac Surg. 2005



The technique of osteotomy plus distraction
osteogenesis is suitable for adult patients. The
technique of sutural distraction osteogenesis is
suitable for young patients, ages 6 through 12
years. The distraction system consists of a facebow, orthodontic elastics, and bone-borne
traction hooks. The bone-borne traction hooks
are made of titanium, with two traction hooks
running laterally or downwardly.



When a Le Fort III osteotomy is needed, boneborne traction hooks are inserted through the
nostrils into a bone hole drilled at the lateralinferior pyriform aperture. When no osteotomy
is needed, only the bone-borne traction hooks
are placed. Heavy elastics were used in the
technique of osteotomy distraction osteogenesis
for Le Fort III osteotomy adult patients,
whereas light forces and thus light elastics were
used for younger patients. Three adult patients
and four children were treated by osteotomy
distraction and sutural distraction, respectively.



All seven patients with midfacial hypoplasia
established a harmonious facial profile and
normal occlusal relationships. Radiographic
examination showed balanced advancement of
the midfacial skeleton. It is suggested that the
treatment of midfacial hypoplasia in children by
the technique of sutural distraction osteogenesis
is to be preferred because of its simplicity and
relative noninvasiveness. Thus, the authors
suggest that midfacial hypoplasia should be
treated at a younger age by this technique,
potentially eliminating the need for a Le Fort III
osteotomy at an older age.

Distraction osteogenesis and periodontal bone
regeneration


Faber J Dent Res. 2005.



The purpose of this study was to test the
hypothesis that periodontium can be
consistently distracted toward the tooth crown
to promote periodontal bone regeneration. After
the surgical production of periodontal defects in
maxillary canines of 5 mongrel dogs, periodontal
bone distraction was performed. Light
microscopy was used for histopathological and
morphometric analysis.



Periodontal bone regeneration occurred in all
animals. Periodontal bone regeneration in the
distraction sites (Mean +/- SD: 5.45 +/- 2.01
mm) differed from that in control sites (0.008
+/- 0.67 mm; p < 0.0001). Periodontal bone
distraction resulted in periodontal bone
regeneration. This finding may establish
periodontal bone distraction as a new treatment
alternative for periodontal defects.

Maxillary distraction osteogenesis to treat maxillary
hypoplasia: comparison of an internal and an
external system.



Kuroda et al AJODO. 2005
DO with a rigid external distraction (RED)
system has been used for maxillary
advancement; however, DO with internal
devices is currently popular. This article
described DO with an internal device and a
RED system in 2 patients with maxillary
hypoplasia with oligodontia. The first patient, a
young girl, had a concave profile due to
maxillary hypoplasia and 9 congenitally missing
permanent teeth.



At age 11 years 11 months, she received DO
with an internal device. The second patient, a
boy aged 11 years 7 months, was treated with
DO with a RED system. In the girl, the maxilla
was advanced 5.0 mm without any dentoalveolar
compensation. In the boy, the maxilla was
advanced 7.0 mm, but undesirable mesial
movement of posterior teeth was observed. It
was concluded that DO with internal devices is
simpler and more useful than the RED system
for maxillary hypoplasia with oligodontia.

Single tooth dento-osseous osteotomy and distraction



Kofod , Wurtz , Melsen AJODO 2005



When teeth are replanted after being avulsed,
the repair process sometimes results in ankylosis.
In a growing child, the ankylosed tooth fails to
move along with the remaining alveolar process
during vertical growth, resulting in a tooth that
gradually appears more and more impacted and
requires several reconstructive procedures to
correct.



Ankylosed teeth can, however, serve as
anchorage for orthodontic correction of a
malocclusion and as a point of force application
for a dentoalveolar segment during alveolar
distraction osteogenesis. A case report described
the treatment of a 13-year-old girl whose
maxillary left central incisor had been avulsed
and replanted 5 years earlier.




The tooth had become ankylosed, and it was
used to provide "free anchorage" during
distalization of the maxillary dentition. The
underdeveloped alveolar process adjacent to the
ankylosed tooth was reconstructed by dentoosseous segment distraction osteogenesis, by
using the ankylosed tooth as the point of force
application.

Indications




Severe retrognathia associated with a syndrome
(eg, Pierre Robin syndrome, Treacher Collins
syndrome), especially in infants and children
who are not candidates for traditional
osteotomies
Unilateral hypoplasia of the mandible (eg,
hemifacial microsomia)








Nonsyndromic mandibular hypoplasia
associated with a dental malocclusion (especially
if the advancement exceeds the capabilities of a
traditional osteotomy or if the patient is hesitant
to undergo a bone graft harvest with the
associated morbidity.
Mandibular transverse deficiency associated with
a dental malocclusion and dental crowding
Severe OSA (respiratory disturbance index
[RDI] >60) and in patients who are obese (body
mass index [BMI] >28)






Mandibular hypoplasia due to trauma and/or
ankylosis of the temporomandibular joint.
Mandibular continuity defects resulting from
excision of tumors and/or aggressive
developmental
Shortened vertical height of the alveolar bone
(Distraction of the alveolar segment can be
performed to increase the vertical height in
preparation for osteointegrated dental implant
placement).



Distraction osteogenesis is showing great
promise in the treatment of OSA. Although
traditional combined maxillary and mandibular
osteotomy are effective in treating mild-tomoderate OSA, the results are disappointing in
patients with severe OSA (RDI >60) and/or a
high BMI (>28).




This is likely because traditional mandibular
osteotomy has a physiologic limit of about 10
mm of advancement, which may be insufficient
to open the airway for effective relief of the
obstruction in the obese patient or in those with
severe disease.




Distraction osteogenesis allows for advancement
of up to 25 mm by using a specially designed
distraction device. In effect, the amount of
distraction is individualized for each patient by
performing polysomnography (PSG) after about
15-18 mm of advancement. If the PSG
demonstrates a normal RDI, distraction is
stopped to allow for consolidation. If the RDI is
still elevated, distraction continues for the full 25
mm.







Contraindications

No absolute contraindications to treatment exist.
However, relative contraindications are as
follows:
Patients who are unable or unwilling to comply
with the distraction schedule are not ideal
candidates for this procedure.
Mandibular distraction osteogenesis has been
performed on infants as young as 6 months, but
more difficulty is encountered when dealing with
small fragile bones in the placement of the
distraction device.







Adequate bone stock must be available to accept
the device and to provide adequate surface area
of the osteotomy sites for regeneration.
Distraction osteogenesis of the mandible may be
used on patients who have received prior
radiation treatment. However, this procedure
must be performed with caution because these
patients are more likely to develop complications
and to experience delays in wound healing.
In older patients, the decreased number of
mesenchymal stem cells may impair bone
healing at the distraction site.

Conclusions


In reality, traditional mandibular and maxillary
osteotomies will always have a role; however,
distraction osteogenesis gives the surgeon
another option in treating a wide variety of
craniofacial deformities.


References






Liou, Huang. Rapid canine retraction through distraction of
the periodontal ligament. Am J Orthod Dentofacial Orthop
1998;114:372-82
Cope, Samchukov. Regenerate Bone Formation and
Remodeling During Mandibular Osteodistraction. Angle
Orthod 2000;70:99–111.
Cope JB, Samchukov ML, Cherkashin AM, Wolford
LM, Franco P. Biomechanics of mandibular distractor
orientation: An animalmodel analysis. J Oral Maxillofac
Surg. 1999;57:952–964.







Graber, Vanarsdall. Orthodontics: Current
Principles & Techniques. 4th Edition. Elsevier
Mosby 2005
Proffit, Fields. Contemporary Orthodontics. 3rd
Edition. Mosby 2000
David M. Sarver. Esthetic Orthodontics &
Orthognathic Surgery. Mosby 1998






Cope JB, Harper RP, Samchukov ML.
Experimental tooth movement through
regenerate alveolar bone: a pilot study. Am J
Orthod Dentofacial Orthop. 1999;116:501–505.
Bell WH, Harper RP, Gonzalez M, Cherkashin
AM, Samchukov ML. Distraction osteogenesis
to widen the mandible. Brit J Oral Maxillofac Surg.
1997;35:11–19.





Tehranch, Behnia. Facial symmetry after
distraction osteogenesis and orthodontic therapy
Am J Orthod Dentofacial Orthop 2001;120:14953
Cope, Samchukov. Mineralisation dynamics of
regenerate bone during mandibular
osterodistraction. Int. J. Oral Maxillofac. Surg,
2001, 30:3





Cope, Samchuko, Cherkashin. Mandibular
distraction osteogenesis: A historic perspective and future
directions Am J Orthod Dentofacial Orthop
1999;115:448-60
Bell , Harper , Gonzalez , Cherkashin ,
Samchukov . Distraction osteogenesis to widen
the mandible. Br J Oral Maxillofac Surg
1997;35:11-9.





Samchukov ML, Cope JB, Harper RP, Ross JD.
Biomechanical considerations for mandibular
lengthening and widening by gradual distraction
using a computer model. Am J Oral
Maxillofacial Surg 1998;56:51-9.
Chin M, Toth BA. Distraction osteogenesis in
maxillofacial surgery using internal devices: a
review of five cases. J Oral Maxillofac Surg
1996;54:45-53.





Yadav, Patil, Keluskar. Canine Distraction: A
review. JIOS 2005, 38; 212-217
Melugin , Hanson , Bergstrom , Schuckit,
Bradley. Soft tissue to hard tissue
advancement ratios for mandibular
elongation using distraction osteogenesis in
children Angle Orthod. 2006 Jan;76(1):72-6.






Cheung,Chua. A meta-analysis of cleft maxillary
osteotomy and distraction osteogenesis. Int J Oral
Maxillofac Surg. 2006 Jan;35(1):14-24.
Liu, Hou, Liang, Huang, Zhang, Zhang H, Ma X, Song.
Sutural distraction osteogenesis (SDO) versus
osteotomy distraction osteogenesis (ODO) for
midfacial advancement: a new technique and
primary clinical report. J Craniofac Surg. 2005
Jul;16(4):537-48






Faber, Azevedo, Bao. Distraction osteogenesis may
promote periodontal bone regeneration. J Dent Res.
2005 Aug;84(8):757-61.
Kuroda, Araki, Oya, Mishima, Sugahara, TakanoYamamoto. Maxillary distraction osteogenesis to
treat maxillary hypoplasia: comparison of an
internal and an external system Am J Orthod
Dentofacial Orthop. 2005 Apr;127(4):493-8.




Kofod, Wurtz, Melsen. Treatment of an
ankylosed central incisor by single tooth
dento-osseous osteotomy and a simple
distraction device. Am J Orthod Dentofacial
Orthop. 2005 Jan;127(1):72-80


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