Distraction 1

DISTRACTIONDISTRACTION
OSTEOGENESIS FOROSTEOGENESIS FOR
CORRECTINGCORRECTING
SKELETAL DYSPLASIASKELETAL DYSPLASIA
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INTRODUCTIONINTRODUCTION
Distraction Osteogenesis is a biologic process that leads toDistraction Osteogenesis is a biologic process that leads to
bone formation between two bony segments that arebone formation between two bony segments that are
mechanically separated at a constant rate. New bone ismechanically separated at a constant rate. New bone is
generated in an osteotomy gap in response to tensiongenerated in an osteotomy gap in response to tension
stresses placed across the bone gap. It enables the clinicianstresses placed across the bone gap. It enables the clinician
to lengthen and widen bone and fill in gaps between bonesto lengthen and widen bone and fill in gaps between bones
without the need for bone or soft tissue grafts. Thewithout the need for bone or soft tissue grafts. The
simultaneous expansion of the soft tissues, includingsimultaneous expansion of the soft tissues, including
muscles, ligaments , fat and skin produces excellentmuscles, ligaments , fat and skin produces excellent
aesthetic and functional results and minimizes the skeletalaesthetic and functional results and minimizes the skeletal
relapse. Distraction Osteogenesis applied to therelapse. Distraction Osteogenesis applied to the
craniofacial skeleton has proven to be a major advance incraniofacial skeleton has proven to be a major advance in
the treatment of congenital deformities. The patientthe treatment of congenital deformities. The patient
population for distraction includes those with craniofacialpopulation for distraction includes those with craniofacial
microsomia , Nager’s syndrome, Treacher Collinsmicrosomia , Nager’s syndrome, Treacher Collins
syndrome, Pierre Robin syndrome, Temperomandibularsyndrome, Pierre Robin syndrome, Temperomandibular
joint ankylosis and post traumatic growth disturbancesjoint ankylosis and post traumatic growth disturbanceswww.indiandentalacademy.com

DEVELOPMENTDEVELOPMENT
 The first bone distraction was performed by CodivillaThe first bone distraction was performed by Codivilla
in 1905 for the treatment of a shortened femur.in 1905 for the treatment of a shortened femur.
Subsequently, Ilizarov introduced distractionSubsequently, Ilizarov introduced distraction
osteogenesis technique for limb lenghthening.osteogenesis technique for limb lenghthening.
 The procedure was initiated by surgical bone divisionThe procedure was initiated by surgical bone division
with maximum preservation of periosteum andwith maximum preservation of periosteum and
endosteum-a technique called corticotomy. Ilizarovendosteum-a technique called corticotomy. Ilizarov
divided two-third of the bony cortex with a narrowdivided two-third of the bony cortex with a narrow
osteotome followed by completion of bone separationosteotome followed by completion of bone separation
with rotational osteoclasiswith rotational osteoclasis

 His distraction protocol used a 5 to 7 day latencyHis distraction protocol used a 5 to 7 day latency
period ( the time frame between bone divisionperiod ( the time frame between bone division
and initiation of traction forces). Bone segmentsand initiation of traction forces). Bone segments
were then gradually separated at a rate of 1 mmwere then gradually separated at a rate of 1 mm
per day in four equal increments of 0.25 mm.per day in four equal increments of 0.25 mm.
 On completion of distraction ,the consolidationOn completion of distraction ,the consolidation
period( the time required for remodeling of theperiod( the time required for remodeling of the
regenerate tissue) began and continued until theregenerate tissue) began and continued until the
newly formed bony tissue in the distraction gapnewly formed bony tissue in the distraction gap
had remodeled.had remodeled.

 Snyder et al in 1973 used Ilizarov’s principle toSnyder et al in 1973 used Ilizarov’s principle to
the mandible.the mandible.
 He resected a unilateral 15 mm bone segmentHe resected a unilateral 15 mm bone segment
from a dog mandible , creating a crossbite. Anfrom a dog mandible , creating a crossbite. An
extraoral distraction appliance was placed.extraoral distraction appliance was placed.
 After 7 day latency period ,device was activatedAfter 7 day latency period ,device was activated
at a rate of 1 mm per day for 14 days at whichat a rate of 1 mm per day for 14 days at which
time occlusion was restored.time occlusion was restored.
 Reestablishment of mandibular cortex andReestablishment of mandibular cortex and
medullary canal across the distraction gap wasmedullary canal across the distraction gap was
noted after 6 weeks of fixation.noted after 6 weeks of fixation.

 In 1976In 1976 Michieli and MiottiMichieli and Miotti, reproduced, reproduced
Snyder’s work,using an intra oral device and inSnyder’s work,using an intra oral device and in
19841984 Kutsevliak and SukachevKutsevliak and Sukachev took thetook the
experiment a step further by lenghthening aexperiment a step further by lenghthening a
normal dog mandible 1.2 cm using Ilizarovnormal dog mandible 1.2 cm using Ilizarov
principle.principle.

 PanikarovskiPanikarovski et al in 1982 performed the first significantet al in 1982 performed the first significant
histologic evaluation of mandibular distractionhistologic evaluation of mandibular distraction
regenerates in 41 days.regenerates in 41 days.
 A fibrous interzone was observed in the central region of the distraction gap withA fibrous interzone was observed in the central region of the distraction gap with
collagenous fibres and capillaries oriented parallel to the direction of distraction.collagenous fibres and capillaries oriented parallel to the direction of distraction.
 Newly created bone ,in the form of longitudinally oriented trabeculae ,originated from theNewly created bone ,in the form of longitudinally oriented trabeculae ,originated from the
residual mandibular segments and progressed towards the fibrous interzone.residual mandibular segments and progressed towards the fibrous interzone.
 Results of these studies demonstrated that the mechanism of new bone formation ,duringResults of these studies demonstrated that the mechanism of new bone formation ,during
gradual mandibular distraction was similar to that during limb lenghthening.gradual mandibular distraction was similar to that during limb lenghthening.

 Karp et al conducted a similar experimentalKarp et al conducted a similar experimental
study with a more comprehensive analysis ofstudy with a more comprehensive analysis of
distraction regenerates at different stages ofdistraction regenerates at different stages of
formation.formation.
 Histomorphologically, the distraction gap wasHistomorphologically, the distraction gap was
represented by four zones-a central zone ofrepresented by four zones-a central zone of
fibrous tissue; a zone of extending bonefibrous tissue; a zone of extending bone
formation; a zone of bone remodeling and aformation; a zone of bone remodeling and a
zone of mature bone.zone of mature bone.
 These studies provided a scientific basis forThese studies provided a scientific basis for
clinical adaptation of the distraction osteogenesisclinical adaptation of the distraction osteogenesis
technique to craniofacial complex.technique to craniofacial complex.

 In 1989, McCarthy et al were the first to clinically applyIn 1989, McCarthy et al were the first to clinically apply
the technique of extraoral osteodistraction on fourthe technique of extraoral osteodistraction on four
children with congenital craniofacial anomalies.children with congenital craniofacial anomalies.
 They used a Hoffman Mini Lengthener attached to theThey used a Hoffman Mini Lengthener attached to the
osteotomized bone segments with two pairs of pins.osteotomized bone segments with two pairs of pins.

 Bone division was initiated by placing a series of drillBone division was initiated by placing a series of drill
holes along the osteotomy line, which were thenholes along the osteotomy line, which were then
connected with a narrow osteotome.connected with a narrow osteotome.
 After a latency of 7 days, lengthening began at a rate ofAfter a latency of 7 days, lengthening began at a rate of
1 mm per day performed in two increments of 0.5 mm.1 mm per day performed in two increments of 0.5 mm.
 After 18 to 24 days of distraction, external fixation wasAfter 18 to 24 days of distraction, external fixation was
maintained for an additional 8 to 10 weeksmaintained for an additional 8 to 10 weeks

 G.Altuna et alG.Altuna et al inin 19951995,performed distraction,performed distraction
osteogenesis of maxilla in adolescent female macacaosteogenesis of maxilla in adolescent female macaca
cynamolgus monkeys.cynamolgus monkeys.
 An orthodontic appliance was constructed with a GlenAn orthodontic appliance was constructed with a Glen
Ross screw oriented antero posteriorly .Ross screw oriented antero posteriorly .
 Anterior sub apical osteotomies of the maxilla wereAnterior sub apical osteotomies of the maxilla were
carried out.carried out.
 Anterior segment was advanced 4 mm in two and 6Anterior segment was advanced 4 mm in two and 6
mm in one monkey and was repaired by well organizedmm in one monkey and was repaired by well organized
alveolar bone at the end of the retention period.alveolar bone at the end of the retention period.

 Histologically the osteotomy site in the lenghthenedHistologically the osteotomy site in the lenghthened
maxilla showed complete regeneration of the alveolarmaxilla showed complete regeneration of the alveolar
crest.crest.
 The height of the alveolar crest in the lenghthenedThe height of the alveolar crest in the lenghthened
osteotomy site was just apical to cementoenamelosteotomy site was just apical to cementoenamel
junction.junction.
 The buccal plate of the lenghthened osteotomy site wasThe buccal plate of the lenghthened osteotomy site was
intact consisting entirely of bone and regeneration ofintact consisting entirely of bone and regeneration of
the osteotomy site was mediated by trabeculae ofthe osteotomy site was mediated by trabeculae of
cancellous bone.cancellous bone.
 The study showed for the first time that distractionThe study showed for the first time that distraction
osteogenesis can be successfully applied to maxilla.osteogenesis can be successfully applied to maxilla.

DEVICES USED IN DISTRACTIONDEVICES USED IN DISTRACTION
OSTEOGENESIS OF THE CRANIOFACIALOSTEOGENESIS OF THE CRANIOFACIAL
SKELETONSKELETON
 Distraction devices can be classified intoDistraction devices can be classified into
 Intraoral devicesIntraoral devices
 Extraoral devicesExtraoral devices
 Extraoral devices can beExtraoral devices can be
 UnidirectionalUnidirectional
 BidirectionalBidirectional
 MultidirectionalMultidirectional
 Intraoral devices can beIntraoral devices can be
 Tooth borneTooth borne
 Bone borneBone borne
 Hybrid (Tooth borne and Bone borne)Hybrid (Tooth borne and Bone borne)

EXTERNAL UNIDIRECTIONAL DISTRACTION DEVICESEXTERNAL UNIDIRECTIONAL DISTRACTION DEVICES
 In 1992,McCarthy et al introduced an external unidirectionalIn 1992,McCarthy et al introduced an external unidirectional
distractor to successfully lengthen the mandible unilaterally in threedistractor to successfully lengthen the mandible unilaterally in three
children and bilaterally in one child.children and bilaterally in one child.
 The amount of distraction varied from 18 mm to 24 mm.The amount of distraction varied from 18 mm to 24 mm.
 The distractor consisted of a single calibrated rod with two clamps.The distractor consisted of a single calibrated rod with two clamps.
 Each clamp holds two 2 mm half pins that are placed on either sideEach clamp holds two 2 mm half pins that are placed on either side
of the osteotomy.of the osteotomy.
 Approximately 20 mm to 24 mm of bone stock posterior to the lastApproximately 20 mm to 24 mm of bone stock posterior to the last
tooth bud is necessary to place this device.tooth bud is necessary to place this device.
 By turning the bolt at the end of the rod ,the distance between theBy turning the bolt at the end of the rod ,the distance between the
clamps can be changed to provide expansion or compression at theclamps can be changed to provide expansion or compression at the
level of the bone.level of the bone.

 Ortiz-Monasterio and Molina modified the IlizarovOrtiz-Monasterio and Molina modified the Ilizarov
technique by performing an incomplete corticotomy.technique by performing an incomplete corticotomy.
 They leave the internal cortical plate and the cancellousThey leave the internal cortical plate and the cancellous
layer intact and use a semi rigid external distractor.layer intact and use a semi rigid external distractor.
 Molina built into his distractor the capability to furtherMolina built into his distractor the capability to further
exploit the secondary soft tissue expansion associatedexploit the secondary soft tissue expansion associated
with osteodistraction.with osteodistraction.
 By leaving the lingual cortical plate intact,initialBy leaving the lingual cortical plate intact,initial
distraction of the device causes the pins to diverge anddistraction of the device causes the pins to diverge and
the expansion rod to bow out.the expansion rod to bow out.
 At some critical point,the inner cortical plate snaps andAt some critical point,the inner cortical plate snaps and
elongation of the bone proceeds.It is believed that theelongation of the bone proceeds.It is believed that the
change in shape of the mandible with this techniquechange in shape of the mandible with this technique
more closely follows the curve of mandibular growth.more closely follows the curve of mandibular growth.

 Despite the fact that the Molina distractors areDespite the fact that the Molina distractors are
unidirectional,changes in three dimensions have beenunidirectional,changes in three dimensions have been
documented.documented.
 A criticism of this technique is the predictability of howA criticism of this technique is the predictability of how
and when the inner cortical plate will break.and when the inner cortical plate will break.
 In situations where there is minimal bone posterior toIn situations where there is minimal bone posterior to
the last tooth bud,a single pin in the proximal segmentthe last tooth bud,a single pin in the proximal segment
may be an advantage over double pins.may be an advantage over double pins.
 If there is inadequate bone for even a single pin, polleyIf there is inadequate bone for even a single pin, polley
and Figueroa advocate the removal of a tooth bud orand Figueroa advocate the removal of a tooth bud or
an interdental osteotomy.an interdental osteotomy.

EXTERNAL BIDIRECTIONAL DISTRACTION DEVICEEXTERNAL BIDIRECTIONAL DISTRACTION DEVICE
 A bidirectional distraction appliance providesA bidirectional distraction appliance provides
an additional degree of freedom over thean additional degree of freedom over the
unidirectional device.unidirectional device.
 More severe mandibular hypoplasias, such asMore severe mandibular hypoplasias, such as
Treacher Collins syndrome and bilateralTreacher Collins syndrome and bilateral
micrognathia, involve deficiencies in more thanmicrognathia, involve deficiencies in more than
one plane.one plane.

 Klein and Howaldt developed an external bi-directional deviceKlein and Howaldt developed an external bi-directional device
capable of achieving controlled changes in angulation. (KLS-capable of achieving controlled changes in angulation. (KLS-
Martin LP).Martin LP).
 Changes can be made in the gonial angle which is often obtuse inChanges can be made in the gonial angle which is often obtuse in
case of mandibular deficiency.case of mandibular deficiency.
 The device consists of two geared arms 5 cm in length connectedThe device consists of two geared arms 5 cm in length connected
to a middle screw that enables the arms to be moved up or downto a middle screw that enables the arms to be moved up or down
to change angulations.to change angulations.

 Molina offers an external bi-directional distractor(WellsMolina offers an external bi-directional distractor(Wells
Johnson Co)based on same principles as hisJohnson Co)based on same principles as his
unidirectional device.unidirectional device.
 Two external corticotomies which preserve the internalTwo external corticotomies which preserve the internal
cortical plate and cancellous bone are performed oncortical plate and cancellous bone are performed on
either side of the gonial angle.either side of the gonial angle.

 A pin is placed in each bony segment for a total ofA pin is placed in each bony segment for a total of
three pins.three pins.
 The combination of an intact lingual cortical plate,theThe combination of an intact lingual cortical plate,the
position of the pins and the flexibility of the deviceposition of the pins and the flexibility of the device
result in closing of the gonial angle and an increase inresult in closing of the gonial angle and an increase in
the convexity of the mandible and overlying soft tissue.the convexity of the mandible and overlying soft tissue.
 The change in gonial angle cannot be preciselyThe change in gonial angle cannot be precisely
controlled because the middle pin only functions as acontrolled because the middle pin only functions as a
pivot.pivot.
 A criticism of the double osteotomy procedure is theA criticism of the double osteotomy procedure is the
risk for avascular necrosis of the intervening segmentrisk for avascular necrosis of the intervening segment
and damage to tooth buds during pin placement.and damage to tooth buds during pin placement.

MULTIPLANAR DISTRACTION DEVICEMULTIPLANAR DISTRACTION DEVICE
 The ability to make transverse changes was the finalThe ability to make transverse changes was the final
step in achieving three diamensional control.step in achieving three diamensional control.
 Building on their previous work, McCarthy et alBuilding on their previous work, McCarthy et al
reported their experience using an external multiplanarreported their experience using an external multiplanar
device(Stryker Leibinger) to correct the asymmetry in adevice(Stryker Leibinger) to correct the asymmetry in a
child with unilateral craniofacial microsomia.child with unilateral craniofacial microsomia.

 The multiplanar device consists of a central housing withThe multiplanar device consists of a central housing with
two work gears in different planes.two work gears in different planes.
 Two arms extend from the housing with pin clamps atTwo arms extend from the housing with pin clamps at
either end.either end.
 Each quarter turn of the wheel results in 0.25 mm ofEach quarter turn of the wheel results in 0.25 mm of
expansion.expansion.
 There is 20 mm of length on each arm for a total of 40There is 20 mm of length on each arm for a total of 40
mm of linear expansion.mm of linear expansion.
 Two activation screws enable changes in the transverse andTwo activation screws enable changes in the transverse and
vertical angulations.vertical angulations.
 Each turn of the screw results in 3 degrees of rotationEach turn of the screw results in 3 degrees of rotation
 KLS-Martin LP also offers a multidirectional distractorKLS-Martin LP also offers a multidirectional distractor
that they recommend for older children.that they recommend for older children.
 The two arms are connected to a middle section by aThe two arms are connected to a middle section by a
ratchet and ball joint combination that allows the arms toratchet and ball joint combination that allows the arms to
move independently of one another. Each arm ismove independently of one another. Each arm is
approximately 60 mm in length.approximately 60 mm in length.www.indiandentalacademy.com

INTERNAL DISTRACTORSINTERNAL DISTRACTORS
 In response to criticism of the external distractors,In response to criticism of the external distractors,
internal devices were developed to eliminate theinternal devices were developed to eliminate the
problems of facial scarring, pin tract infections and highproblems of facial scarring, pin tract infections and high
visibility.visibility.
 It should be kept in mind that at this time,internalIt should be kept in mind that at this time,internal
devices are capable of unidirectional distraction only.devices are capable of unidirectional distraction only.
 InIn 1995,McCarthy1995,McCarthy et alet al introduced an intraoralintroduced an intraoral
distraction appliance tested on the canine model.distraction appliance tested on the canine model.
 After performing an osteotomy,the device was placedAfter performing an osteotomy,the device was placed
on the buccal surface of the mandible and theon the buccal surface of the mandible and the
lenghthening rod was extended into the buccallenghthening rod was extended into the buccal
vestibule.vestibule.
 A drawback of the appliance was that it could onlyA drawback of the appliance was that it could only
accommodate 20 mm of expansion.accommodate 20 mm of expansion.

 Drs Vasquez and Diner,Drs Vasquez and Diner, from the Armand-Trousseau Childrensfrom the Armand-Trousseau Childrens
Hospital in Paris,developed two internal distractors,one forHospital in Paris,developed two internal distractors,one for
lenghthening the mandibular body and the other for lenghtheninglenghthening the mandibular body and the other for lenghthening
the ramus (Stryker Leibinger).the ramus (Stryker Leibinger).
 Each device comes in two sizes to enable 18 mm or 28 mm ofEach device comes in two sizes to enable 18 mm or 28 mm of
expansion and is held in place by four 1.6 mm self-drilling pins.expansion and is held in place by four 1.6 mm self-drilling pins.
 The rod attachment used to activate expansion is available in sizesThe rod attachment used to activate expansion is available in sizes
varying from 83 mm to 123 mm in length.varying from 83 mm to 123 mm in length.
 The rod extends into the buccal sulcus and rests between the lipsThe rod extends into the buccal sulcus and rests between the lips
for easy access.for easy access.

 Synthes Maxillofacial(Paoli,PA) manufactures a partiallySynthes Maxillofacial(Paoli,PA) manufactures a partially
internalized distractor capable of 30 mm of distraction.internalized distractor capable of 30 mm of distraction.
 The distractor is held in placeThe distractor is held in place
by four 2 mm self tapping screws,by four 2 mm self tapping screws,
and the expansion rod is fully enclosedand the expansion rod is fully enclosed
to provide comfort and to minimizeto provide comfort and to minimize
any soft tissue interference.any soft tissue interference.
 KLS-Martin LP manufactures a miniaturized intraoralKLS-Martin LP manufactures a miniaturized intraoral
mandibular distractor with a flexible arm that exitsmandibular distractor with a flexible arm that exits
percutaneously.percutaneously.
 There are three sizes,allowing 10 mm, 15 mm, or 20 mmThere are three sizes,allowing 10 mm, 15 mm, or 20 mm
of distraction and they are held in place by a total of sixof distraction and they are held in place by a total of six
1.5 mm screws.1.5 mm screws.

TOOTH-BORNE APPLIANCESTOOTH-BORNE APPLIANCES
 In 1997,Razdolsky et al introduced a completely tooth-borneIn 1997,Razdolsky et al introduced a completely tooth-borne
intraoral distractor capable of making linear changes (Oralintraoral distractor capable of making linear changes (Oral
Osteodistraction LC).Osteodistraction LC).
 Current technique starts by fittingCurrent technique starts by fitting
preformed stainless steel crowns to onepreformed stainless steel crowns to one
tooth on either side of the anticipatedtooth on either side of the anticipated
osteotomy site( usually the second molarosteotomy site( usually the second molar
and first bicuspid teeth).and first bicuspid teeth).
 Rubber base impression is taken of the entire arch, and theRubber base impression is taken of the entire arch, and the
distractor is fabricated on the cast by the laboratory.distractor is fabricated on the cast by the laboratory.
 The stainless steel crowns are cemented before surgery. AnThe stainless steel crowns are cemented before surgery. An
osteotomy is made between the selected teeth,and the expandersosteotomy is made between the selected teeth,and the expanders
are placed to complete the ROD (Razdolsky Osteogenesisare placed to complete the ROD (Razdolsky Osteogenesis
Device) appliance.Device) appliance.

 There are several ROD appliances available, with sizesThere are several ROD appliances available, with sizes
enabling 11 mm to 15 mm of distraction.enabling 11 mm to 15 mm of distraction.
 In addition to the ROD 1 used to distract between teethIn addition to the ROD 1 used to distract between teeth
to increase arch length, the ROD 2 ( partially toothto increase arch length, the ROD 2 ( partially tooth
borne/partially bone borne) advances the mandibleborne/partially bone borne) advances the mandible
posterior to the last molar; the ROD 3 widens theposterior to the last molar; the ROD 3 widens the
mandible; ROD 4 is designed for maxillary distraction andmandible; ROD 4 is designed for maxillary distraction and
ROD 5 is designed for ridge augmentation.ROD 5 is designed for ridge augmentation.

MANDIBULAR WIDENING DEVICEMANDIBULAR WIDENING DEVICE
 Early application of distraction osteogenesis to widen the mandibleEarly application of distraction osteogenesis to widen the mandible
was described by Guerrero and Contasti.was described by Guerrero and Contasti.
 Bands were fitted on the lower first bicuspids and molars, and aBands were fitted on the lower first bicuspids and molars, and a
jackscrew was soldered at the midline for expansion.jackscrew was soldered at the midline for expansion.
 Harper et al and Bell et al performed mandibular midlineHarper et al and Bell et al performed mandibular midline
osteotomies in adult monkeys employing cemented Hyrax-typeosteotomies in adult monkeys employing cemented Hyrax-type
expansion appliances.expansion appliances.
 Guerrero et al reported their findings after redesigning theGuerrero et al reported their findings after redesigning the
mandibular midline distractor to provide bony anchorage(Dynaformmandibular midline distractor to provide bony anchorage(Dynaform
Intraoral Distraction Device; Stryker Leibinger)Intraoral Distraction Device; Stryker Leibinger)

RIDGE AUDMENTATIONRIDGE AUDMENTATION
 Chin and TothChin and Toth performed vertical alveolar distraction inperformed vertical alveolar distraction in
a 17 year old girl with a Knife-edged ridge that madea 17 year old girl with a Knife-edged ridge that made
placement of implants impossible without augmentation.placement of implants impossible without augmentation.
 The distractor (LEAD System, Stryker Leibinger) wasThe distractor (LEAD System, Stryker Leibinger) was
placed and after a latency period of 5 days, distractionplaced and after a latency period of 5 days, distraction
proceeded at a rate of 1 mm per day for 9 days.proceeded at a rate of 1 mm per day for 9 days.
 The device was retained for 10 days, at which time it wasThe device was retained for 10 days, at which time it was
removed. After 6 weeks, Osseointegrated implants wereremoved. After 6 weeks, Osseointegrated implants were
placed in the greatly increased mass of boneplaced in the greatly increased mass of bone

MIDFACE DISTRACTIONMIDFACE DISTRACTION
 After the successful application of distractionAfter the successful application of distraction
osteogenesis in the human mandible, it was onlyosteogenesis in the human mandible, it was only
a matter of time before the technique wasa matter of time before the technique was
applied to the midface.applied to the midface.
 In 1993,Rachmiel et al reported their findings onIn 1993,Rachmiel et al reported their findings on
midface advancement in sheep using externalmidface advancement in sheep using external
distractors.distractors.

 Molina and Ortiz-Monisterio reported using anMolina and Ortiz-Monisterio reported using an
orthodontic face protraction mask combined with a Leorthodontic face protraction mask combined with a Le
Fort I osteotomy to achieve distraction osteogenesis.Fort I osteotomy to achieve distraction osteogenesis.
 After attempting this technique,Polley and FigueroaAfter attempting this technique,Polley and Figueroa
realized that the facemask with elastics was not sufficientlyrealized that the facemask with elastics was not sufficiently
rigid to achieve the desired amount of forward movement.rigid to achieve the desired amount of forward movement.
 They developed an adjustableThey developed an adjustable
rigid external fixationrigid external fixation
(RED;KLS-Martin LP)(RED;KLS-Martin LP)
system for maxillarysystem for maxillary
advancement.advancement.

 The distraction device is symmetrically positioned andThe distraction device is symmetrically positioned and
secured with two to three scalp screws.secured with two to three scalp screws.
 Tracing wire is connected from the extraoral hooksTracing wire is connected from the extraoral hooks
extending from the splint to the horizontal bar on theextending from the splint to the horizontal bar on the
distractor.distractor.
 The horizontal bar of the device can be adjusted up andThe horizontal bar of the device can be adjusted up and
down to allow multiplanar control of the vertical as welldown to allow multiplanar control of the vertical as well
as the horizontal movements.as the horizontal movements.
 Retention is continued by wearing an orthodonticRetention is continued by wearing an orthodontic
facemask with elastics at night for 4 to 6 weeks.facemask with elastics at night for 4 to 6 weeks.
 They reported using the RED appliance in a 10 year oldThey reported using the RED appliance in a 10 year old
child with severe maxillary hypoplasia as a result ofchild with severe maxillary hypoplasia as a result of
bilateral cleft lip and palate.The device was simple tobilateral cleft lip and palate.The device was simple to
use and the scalp screws did not cause any problems.use and the scalp screws did not cause any problems.

 MolinaMolina designed a unidirectional orbital malardesigned a unidirectional orbital malar
distractor that is used in conjunction with a Ledistractor that is used in conjunction with a Le
Fort III osteotomy(Wells Johnson Co).Fort III osteotomy(Wells Johnson Co).
 The self contained rod is smooth and facilitatesThe self contained rod is smooth and facilitates
function and comfort.function and comfort.
 The active portion of the rod exitsThe active portion of the rod exits
percutaneously behind the ear and can bepercutaneously behind the ear and can be
expanded up to 25 mm.expanded up to 25 mm.
 The anterior point of the device has a pointThe anterior point of the device has a point
pivot that allows flexibility in placement behindpivot that allows flexibility in placement behind
the malar bone.the malar bone.

 Chin and TothChin and Toth custom designed their own internalcustom designed their own internal
distraction devices for use in the maxillofacial complex.distraction devices for use in the maxillofacial complex.
 Models of the skeleton are milled from computedModels of the skeleton are milled from computed
tomographic data to plan the surgery and design theirtomographic data to plan the surgery and design their
distractors.distractors.
 Chin and Toth,s approach to distraction departs fromChin and Toth,s approach to distraction departs from
the principles outlined by Ilizarov in several ways.the principles outlined by Ilizarov in several ways.
 In their surgical technique for midface advancementIn their surgical technique for midface advancement
Toth et al create proximal boxes to seat the device.Toth et al create proximal boxes to seat the device.
 The forces of distraction are transmitted directly againstThe forces of distraction are transmitted directly against
the bone,rather than creating a torturing force that maythe bone,rather than creating a torturing force that may
dislodge the retention screws.dislodge the retention screws.

DISTRACTION IN INFANTSDISTRACTION IN INFANTS
 In 1994,McCarthy suggested that distractionIn 1994,McCarthy suggested that distraction
could be performed in children as young as 2could be performed in children as young as 2
years of age.years of age.
 As the knowledge of distraction osteogenesisAs the knowledge of distraction osteogenesis
has increased, the technique has beenhas increased, the technique has been
successfully applied to infants with severesuccessfully applied to infants with severe
deficiencies that require immediate intervention.deficiencies that require immediate intervention.

 Cohen et al introduced a system of miniatureCohen et al introduced a system of miniature
distractors that could be customized for use anywheredistractors that could be customized for use anywhere
in the craniofacial complex.in the craniofacial complex.
Facial moulages of the infant were taken to aid in theFacial moulages of the infant were taken to aid in the
design of the device.design of the device.
 A modified Le Fort III osteotomy with internal orbitalA modified Le Fort III osteotomy with internal orbital
osteotomies and a mandibular osteotomy wereosteotomies and a mandibular osteotomy were
performed.performed.
 The distraction devices were placed to correct theThe distraction devices were placed to correct the
sagittal and vertical maxillary deficiency,expand thesagittal and vertical maxillary deficiency,expand the
orbit and increase mandibular body length.orbit and increase mandibular body length.
 Each vector was chosen independently,the devices wereEach vector was chosen independently,the devices were
custom modified and multiple distractions proceededcustom modified and multiple distractions proceeded
simultaneously.simultaneously.

 Cohen further developed his miniature distractionCohen further developed his miniature distraction
devices,called the Modular Internal Distraction(MID)devices,called the Modular Internal Distraction(MID)
system(Stryker Leibinger)system(Stryker Leibinger)
 This is the first internal distraction system approved byThis is the first internal distraction system approved by
the Food and Drug Administration for marketing. Twothe Food and Drug Administration for marketing. Two
distractor frames are available to provide 15 mm or 30distractor frames are available to provide 15 mm or 30
mm of distraction.mm of distraction.

 The frames are attached to 1.7 mm mini Wurzburg threeThe frames are attached to 1.7 mm mini Wurzburg three
dimensional mesh plates of varying sizes using 1.6 mmdimensional mesh plates of varying sizes using 1.6 mm
connecting screws.connecting screws.
 There is a flexible activation cable that exits percutaneously;There is a flexible activation cable that exits percutaneously;
preauricularly or postauricularly, through the scalp orpreauricularly or postauricularly, through the scalp or
intraorally.intraorally.
 It is recommended that a complete osteotomy be performedIt is recommended that a complete osteotomy be performed
with a latency period of 5 to 7 days, followed by 1 mm perwith a latency period of 5 to 7 days, followed by 1 mm per
day of distraction and a consolidation period of 8 to 12day of distraction and a consolidation period of 8 to 12
weeks.weeks.
 These devices can also be used in older children.These devices can also be used in older children.

 Molina(Wells Johnson Co) offers a unidirectional BabyMolina(Wells Johnson Co) offers a unidirectional Baby
Mandibular Distractor designed for infants.Mandibular Distractor designed for infants.
 It is 50% smaller and lighter than the standard unidirectionalIt is 50% smaller and lighter than the standard unidirectional
distractor.distractor.
 Bilateral corticotomies are performed at the mandibular angleBilateral corticotomies are performed at the mandibular angle
behind the most posterior tooth bud.behind the most posterior tooth bud.
 A long continuous pin is used to penetrate bothA long continuous pin is used to penetrate both
proximalsegment to provide increased strength and stabilityproximalsegment to provide increased strength and stability
across the arch.across the arch.
 Individual pins are placed in the distal segments and the devicesIndividual pins are placed in the distal segments and the devices
are mounted.are mounted.
 Rodrigues and DogliottiRodrigues and Dogliotti described mandibular lenghtheningdescribed mandibular lenghthening
with a simple custom designed appliance to bring the base of thewith a simple custom designed appliance to bring the base of the
tongue forward in three newborn infants with glossotosis-tongue forward in three newborn infants with glossotosis-
micrognathic association.micrognathic association.
 The surgical technique was the same as outlined by Molina ,butThe surgical technique was the same as outlined by Molina ,but
Rodriguez and Dogliotti used a long K-wire in place of theRodriguez and Dogliotti used a long K-wire in place of the
continuous pin.continuous pin.

PRINCIPLES OF DISTRACTIONPRINCIPLES OF DISTRACTION
OSTEOGENESISOSTEOGENESIS
(ILIZAROV PRINCIPLES)(ILIZAROV PRINCIPLES)
 1. BONE CUT: It is important to preserve the osseous blood supply.1. BONE CUT: It is important to preserve the osseous blood supply.
Because of the abundant vascular supply of the craniofacialBecause of the abundant vascular supply of the craniofacial
skeleton,either an osteotomy or corticotomy may be performed.skeleton,either an osteotomy or corticotomy may be performed.
It is common to initially create a corticotomy in deficient mandibleIt is common to initially create a corticotomy in deficient mandible
which then can be converted to an osteotomy.which then can be converted to an osteotomy.
It is also important to preserve the integrity of the overlying periostealIt is also important to preserve the integrity of the overlying periosteal
envelope during surgery.envelope during surgery.
 2. LATENCY : After bone cut is performed,a latency period of 5 to 72. LATENCY : After bone cut is performed,a latency period of 5 to 7
days is observed before device activation.days is observed before device activation.
This allows for the formation of an adequate fibrovascular bridgeThis allows for the formation of an adequate fibrovascular bridge
between the bone edges.between the bone edges.
Additionally ,the surgical site passes into Phase II of wound healing,Additionally ,the surgical site passes into Phase II of wound healing,
promoting a regenerative environment.promoting a regenerative environment.
Latency period may be shortened (1 to 2 days) if the patient is young.Latency period may be shortened (1 to 2 days) if the patient is young.

 3. RATE: A regenerate can best be generated when the tensile3. RATE: A regenerate can best be generated when the tensile
stress is applied and bone edges separated 1.0 mm per day.stress is applied and bone edges separated 1.0 mm per day.
For young child,the rate may be increased upto 1.5 to 2 mm perFor young child,the rate may be increased upto 1.5 to 2 mm per
day.day.
Advancing the bone segments more than 2 mm per day mayAdvancing the bone segments more than 2 mm per day may
exceed the limit of vascular supply of the overlying soft tissue.exceed the limit of vascular supply of the overlying soft tissue.
 4. RHYTHM : Continuous application of distraction force is4. RHYTHM : Continuous application of distraction force is
ideal.ideal.
Clinically, application of the distraction is best performed byClinically, application of the distraction is best performed by
activating the device twice a day(0.5 mm twice a day).activating the device twice a day(0.5 mm twice a day).
If the patient experiences discomfort ,then the rhythm should beIf the patient experiences discomfort ,then the rhythm should be
altered to allow for a smaller incremental application(0.25 mmaltered to allow for a smaller incremental application(0.25 mm
for four times a day)for four times a day)

 5. CONSOLIDATION : Once the regenerate has been created,the5. CONSOLIDATION : Once the regenerate has been created,the
distraction device is held in neutral fixation allowing the neomandibledistraction device is held in neutral fixation allowing the neomandible
to ossify.to ossify.
The timing of the ossification process is similar to that of fractureThe timing of the ossification process is similar to that of fracture
healing(6 to 8 weeks). For younger children ,ossification can occurhealing(6 to 8 weeks). For younger children ,ossification can occur
quicker.quicker.
It is best to observe a cortical outline on the radiograph of theIt is best to observe a cortical outline on the radiograph of the
regenerate before device removal.regenerate before device removal.
 Jason Cope et al in Int.J.Oral &Maxillofacial surgeryJason Cope et al in Int.J.Oral &Maxillofacial surgery inin 20012001 usedused
digital subtraction radiography for monitoring distraction regeneratedigital subtraction radiography for monitoring distraction regenerate
formation.formation.
 Subtraction radiography is a method by which two virtually identicalSubtraction radiography is a method by which two virtually identical
serial radiographs, taken under the same conditions, can beserial radiographs, taken under the same conditions, can be
superimposed, common anatomical structures subtracted, and thesuperimposed, common anatomical structures subtracted, and the
difference quantified in terms of net gain(increased mineralisation) ordifference quantified in terms of net gain(increased mineralisation) or
net loss(decreased mineralisation).net loss(decreased mineralisation).
 They showed Digital Subtraction Radiography to be highly sensitiveThey showed Digital Subtraction Radiography to be highly sensitive
and accurate for detecting bone mineral changesand accurate for detecting bone mineral changeswww.indiandentalacademy.com

STAGES IN THE DEVELOPMENT OF BONYSTAGES IN THE DEVELOPMENT OF BONY
REGENERATEREGENERATE
1.1. The “Stage of fibrous tissue” consisting of highly organized,The “Stage of fibrous tissue” consisting of highly organized,
longitudinally oriented parallel strands of collagen withlongitudinally oriented parallel strands of collagen with
spindle shaped fibroblasts and undifferentiatedspindle shaped fibroblasts and undifferentiated
mesenchymal precursor cells throughout the matrix.mesenchymal precursor cells throughout the matrix.

2.2. The “Stage of extending bone formation” in whichThe “Stage of extending bone formation” in which
fibroblasts and undifferentiated precursor cells of thefibroblasts and undifferentiated precursor cells of the
matrix were in continuity with osteoblasts.matrix were in continuity with osteoblasts.
The osteoblasts had a longitudinal orietation.The osteoblasts had a longitudinal orietation.
The osteoblasts arouse from transformed spindle shapedThe osteoblasts arouse from transformed spindle shaped
fibroblastic cells located between the collagen bundles.fibroblastic cells located between the collagen bundles.
3.3. The “Stage of bone remodeling” consisting of advancingThe “Stage of bone remodeling” consisting of advancing
fields of bone resorption and apposition. There werefields of bone resorption and apposition. There were
increased numbers of osteoclasts.increased numbers of osteoclasts.
4.4. The “Stage of mature bone” in which compact corticalThe “Stage of mature bone” in which compact cortical
bone was located adjacent to the mature bone in thebone was located adjacent to the mature bone in the
nondistracted areas.The bone spicules were thicker andnondistracted areas.The bone spicules were thicker and
less longitudinal than in the remodeling stageless longitudinal than in the remodeling stage

MAXILLARY DISTRACTIONMAXILLARY DISTRACTION
 Alvaro.Figueroa et alAlvaro.Figueroa et al inin AJO 99AJO 99 reported of maxillaryreported of maxillary
distraction osteogenesis in cleft patients with severedistraction osteogenesis in cleft patients with severe
maxillary deficiency, with the use of a rigid externalmaxillary deficiency, with the use of a rigid external
distraction (RED) device.distraction (RED) device.
 Patients are evaluated employing a comprehensivePatients are evaluated employing a comprehensive
clinical examination, facial and intraoral photographs,clinical examination, facial and intraoral photographs,
cephalometric and panoramic radiographs, dental casts,cephalometric and panoramic radiographs, dental casts,
video imaging, computerized axial tomographic scansvideo imaging, computerized axial tomographic scans
and a comprehensive speech evaluation.and a comprehensive speech evaluation.

 A patient having the following characteristics isA patient having the following characteristics is
considered for maxillary advancement throughconsidered for maxillary advancement through
distraction osteogenesis with the use of REDdistraction osteogenesis with the use of RED
systemsystem
 Transverse,vertical and horizontal maxillaryTransverse,vertical and horizontal maxillary
deficiency needing an advancement greater than 6deficiency needing an advancement greater than 6
mm to 8 mmmm to 8 mm
 palatal clefts with severe scarringpalatal clefts with severe scarring
 normal mandibular morphology and positionnormal mandibular morphology and position
 normal neck/chin anglenormal neck/chin angle
 patients in the full primary dentition or olderpatients in the full primary dentition or older
 patients with an intact craniumpatients with an intact cranium

 To deliver the distraction forces to the maxilla, a customTo deliver the distraction forces to the maxilla, a custom
made semirigid intraoral splint is fabricated.made semirigid intraoral splint is fabricated.
 The orthodontic maxillary bands with 0.050 inch headgearThe orthodontic maxillary bands with 0.050 inch headgear
tubes are fitted on the first permanent molar teeth, or ontubes are fitted on the first permanent molar teeth, or on
the second primary molars in young children.the second primary molars in young children.
 An impression is obtained of the maxillary arch and theAn impression is obtained of the maxillary arch and the
bands are transferred from the mouth to the impression tobands are transferred from the mouth to the impression to
prepare a working dental cast.prepare a working dental cast.

 If the arch is small or irregular ,a custom made device hasIf the arch is small or irregular ,a custom made device has
to be fabricated. Labial and palatal 0.045 or 0.050to be fabricated. Labial and palatal 0.045 or 0.050
stainless steel wires are bent around the perimeter of thestainless steel wires are bent around the perimeter of the
dental arch as close as possible to the labial or palataldental arch as close as possible to the labial or palatal
aspect of the teeth.aspect of the teeth.
 If orthodontic appliances are present ,the wires must beIf orthodontic appliances are present ,the wires must be
bent to clear the brackets, thereby facilitating the path ofbent to clear the brackets, thereby facilitating the path of
insertion.insertion.
 The wires are then soldered to the molar bands.The wires are then soldered to the molar bands.
 If additional rigidity is required, stability wires can beIf additional rigidity is required, stability wires can be
soldered between the labial and palatal wires across thesoldered between the labial and palatal wires across the
dental embrasures, usually distal to the lateral incisors ondental embrasures, usually distal to the lateral incisors on
both sides or a trans palatal bar added.both sides or a trans palatal bar added.

 Two straight pieces of heavy rigid stainless steelTwo straight pieces of heavy rigid stainless steel
orthodontic wires(0.060 inch or heavier) are solderedorthodontic wires(0.060 inch or heavier) are soldered
perpendicular to the labial wire just distal to the lateralperpendicular to the labial wire just distal to the lateral
incisors or medial to both lip commisures.incisors or medial to both lip commisures.
 The gingival intraoral aspect of the wire is cut short andThe gingival intraoral aspect of the wire is cut short and
bent like a hook to be used for face mask elastic tractionbent like a hook to be used for face mask elastic traction

 This gingival hook will be used during the retentionThis gingival hook will be used during the retention
phase after the distraction has been completed.phase after the distraction has been completed.
 The occlusal or caudal aspect of the wire is left long soThe occlusal or caudal aspect of the wire is left long so
it can be bent over and anterior to the upper lip forit can be bent over and anterior to the upper lip for
comfort.comfort.
 The end of this external wire is eventually bent into anThe end of this external wire is eventually bent into an
eyelet from which the splint and the distraction screweyelet from which the splint and the distraction screw
of the RED device are connected by means of aof the RED device are connected by means of a
surgical wire.surgical wire.
 The traction hook is usually located at or above theThe traction hook is usually located at or above the
approximate center of mass of the osteotomizedapproximate center of mass of the osteotomized
maxilla.maxilla.
 In patients without osteotomies, the center ofIn patients without osteotomies, the center of
resistance of the maxilla has been estimated to be at theresistance of the maxilla has been estimated to be at the
level of the apices of the second bicuspids.level of the apices of the second bicuspids.

 This guideline can be used to determine the position of theThis guideline can be used to determine the position of the
traction hooks.traction hooks.
 A force vector through the centerof maas of the maxillaA force vector through the centerof maas of the maxilla
will advance it linearly, whereas a force vector above thewill advance it linearly, whereas a force vector above the
center of mass will create a clockwise rotation and onecenter of mass will create a clockwise rotation and one
below it a counterclockwise rotation.below it a counterclockwise rotation.
 If the arch form is fairly symmetrical, an orthodonticIf the arch form is fairly symmetrical, an orthodontic
Facebow can be used for making the splint.Facebow can be used for making the splint.
 Expansion procedures are better to be carried out beforeExpansion procedures are better to be carried out before
or after distraction.or after distraction.
 Once the splint is completed,it is tried on the patient forOnce the splint is completed,it is tried on the patient for
appropriate fit,any adjustments are made, and then it isappropriate fit,any adjustments are made, and then it is
cemented in place with orthodontic glass ionomer cement.cemented in place with orthodontic glass ionomer cement.
 This is usually performed the day before surgery.In youngThis is usually performed the day before surgery.In young
or uncooperative chidren,it may be necessary to cementor uncooperative chidren,it may be necessary to cement
the splint in the operating room after anaesthesia.the splint in the operating room after anaesthesia.www.indiandentalacademy.com

 Before the osteotomy intraoral splint is secured with multipleBefore the osteotomy intraoral splint is secured with multiple
circumdental wires to create a completely rigid appliance so thatcircumdental wires to create a completely rigid appliance so that
the distraction forces are transmitted to various teeth and notthe distraction forces are transmitted to various teeth and not
only to the molars on which the bands have been cemented.only to the molars on which the bands have been cemented.
 The maxillary hypoplasia in cleft patients is usually not restrictedThe maxillary hypoplasia in cleft patients is usually not restricted
to the dento-alveolar segment,but includes the paranasal,to the dento-alveolar segment,but includes the paranasal,
infraorbital and malar regions.infraorbital and malar regions.
 For this reason a high Le Fort I osteotomy is usually performedFor this reason a high Le Fort I osteotomy is usually performed
for patients undergoing maxillary distraction.for patients undergoing maxillary distraction.
 The transverse osteotomy is performed high,extending laterallyThe transverse osteotomy is performed high,extending laterally
across the maxilla below or circumventing the infraorbitalacross the maxilla below or circumventing the infraorbital
foramen.foramen.
 The lateral aspect of the transverse osteotomy can be extendedThe lateral aspect of the transverse osteotomy can be extended
to a variable degree to include the zygomatic or malar projection.to a variable degree to include the zygomatic or malar projection.
 In children sufficient bone is left cranial to the tooth buds toIn children sufficient bone is left cranial to the tooth buds to
avoid disturbing them.avoid disturbing them.

 The osteotomy is complete with septal and pterygoidThe osteotomy is complete with septal and pterygoid
dysjunction,but in children ,minimal downfracturing is performed todysjunction,but in children ,minimal downfracturing is performed to
avoid damage to developing tooth bud . Complete down fracturingavoid damage to developing tooth bud . Complete down fracturing
of the maxilla is not necessary .of the maxilla is not necessary .
 Following intraoral soft tissue closure,the cranial halo component ofFollowing intraoral soft tissue closure,the cranial halo component of
the RED device is placed.the RED device is placed.
 The halo is placed parallel to the Frankfort horizontal plane and justThe halo is placed parallel to the Frankfort horizontal plane and just
above the temporalis muscle.above the temporalis muscle.
 Two to three scalp screws on each side are used for fixation.Two to three scalp screws on each side are used for fixation.

 Three to five days after surgery, the vertical bar of the REDThree to five days after surgery, the vertical bar of the RED
device is placed in the center of the face , sufficiently anteriordevice is placed in the center of the face , sufficiently anterior
and also parallel to the facial plane. and the distraction system areand also parallel to the facial plane. and the distraction system are
connected to the halo.connected to the halo.
 The distraction screws ,mounted on the horizontal bars, areThe distraction screws ,mounted on the horizontal bars, are
placed at the apprapriate level to obtain the necessary vectors forplaced at the apprapriate level to obtain the necessary vectors for
the desired maxillary movement.the desired maxillary movement.
 A 25 gauge surgical wire is used to connect the traction hookA 25 gauge surgical wire is used to connect the traction hook
from the intraoral splint to the distraction screws.Distraction isfrom the intraoral splint to the distraction screws.Distraction is
performed at home by turning the activating screw at a rate of 1performed at home by turning the activating screw at a rate of 1
mm to 1.5 mm per day.mm to 1.5 mm per day.

 Force levels may have to be increased during the later stages ofForce levels may have to be increased during the later stages of
distraction because consolidation of callus provides resistance todistraction because consolidation of callus provides resistance to
the advancement.the advancement.
 Once the appropriate maxillary advancement has been achieved,theOnce the appropriate maxillary advancement has been achieved,the
RED system is left in place for 2 to 3 weeks to permit boneRED system is left in place for 2 to 3 weeks to permit bone
consolidation.consolidation.
 After the RED device is removed ,the external traction hooks areAfter the RED device is removed ,the external traction hooks are
cut with a rotating disk.cut with a rotating disk.
 The retention after distraction consists of nightly use of face maskThe retention after distraction consists of nightly use of face mask
elastic traction (12 to 16 oz) for 6 to 8 weeks.elastic traction (12 to 16 oz) for 6 to 8 weeks.

 Maxillary advancement using distraction osteogenesis has severalMaxillary advancement using distraction osteogenesis has several
advantages which include the ability to treat skeletal dysplasias atadvantages which include the ability to treat skeletal dysplasias at
a young age without having to wait until skeletal maturity.a young age without having to wait until skeletal maturity.
 It also treats only the affected maxilla without having to operateIt also treats only the affected maxilla without having to operate
on the normally positioned or even small mandible.on the normally positioned or even small mandible.
 The surgical procedure is simplified with minimal morbidity andThe surgical procedure is simplified with minimal morbidity and
no need for blood transfusions,bone grafts or rigid fixationno need for blood transfusions,bone grafts or rigid fixation
hardware.hardware.
 The design of the RED device is such that it allows forThe design of the RED device is such that it allows for
adjustments of the distraction force vectors during the distractionadjustments of the distraction force vectors during the distraction
process.process.
 Limitations of the technique relates to patients with completeLimitations of the technique relates to patients with complete
absence of teeth or lack of adequate bone in the cranial vault.absence of teeth or lack of adequate bone in the cranial vault.
 In patients without a healthy dentition or with multiple missingIn patients without a healthy dentition or with multiple missing
teeth,it may be necessary to use osseointegrated implants orteeth,it may be necessary to use osseointegrated implants or
skeletal anchorage for traction hooks.skeletal anchorage for traction hooks.

BIOMECHANICAL CONSIDERATIONSBIOMECHANICAL CONSIDERATIONS
 After a complete Le Fort I osteotomy, the dentomaxillaryAfter a complete Le Fort I osteotomy, the dentomaxillary
complex is no longer a constrained skeletal structure andcomplex is no longer a constrained skeletal structure and
therefore the location of its center of resistance is nottherefore the location of its center of resistance is not
applicable in forecasting protractive movement.applicable in forecasting protractive movement.
 Rather,the dentomaxillary complex has been altered to aRather,the dentomaxillary complex has been altered to a
relatively free structure.relatively free structure.
 Consequently,the point of application and line of action ofConsequently,the point of application and line of action of
distraction forces relative to its center of mass becomesdistraction forces relative to its center of mass becomes
important.important.
 The center of mass of the dentomaxillary complex isThe center of mass of the dentomaxillary complex is
significantly influenced by the disparity in density(mass persignificantly influenced by the disparity in density(mass per
unit volume) between its osseous and dental structures.unit volume) between its osseous and dental structures.
 Location of center of mass will be affected by sizeLocation of center of mass will be affected by size
(maturation) of the osseous structures,the number of teeth(maturation) of the osseous structures,the number of teeth
present and surgical design of the osteotomypresent and surgical design of the osteotomy

 Experiments byExperiments by Gyn Ahn et alGyn Ahn et al inin AJO 99AJO 99 on anon an
osteotomised dentomaxillary structure from anosteotomised dentomaxillary structure from an
adult cadaver showed the center of mass in theadult cadaver showed the center of mass in the
sagittal view as being located on a line along thesagittal view as being located on a line along the
mesial aspect of the maxillary first molar rootmesial aspect of the maxillary first molar root
14.66 mm superior to its occlusal surface14.66 mm superior to its occlusal surface

 If linear protraction of the osteotomised dentomaxillaryIf linear protraction of the osteotomised dentomaxillary
complex is desired parallel to the functional occlusalcomplex is desired parallel to the functional occlusal
plane, the line of action of the distraction forces wouldplane, the line of action of the distraction forces would
pass through the center of mass and be parallel to thepass through the center of mass and be parallel to the
functional occlusal plane.functional occlusal plane.
 On the other hand,if downward and forward rotation isOn the other hand,if downward and forward rotation is
desired then the line of action of applied forces would bedesired then the line of action of applied forces would be
placed superior to center of mass and parallel toplaced superior to center of mass and parallel to
functional occlusion.functional occlusion.
 The position of traction hooks and the direction ofThe position of traction hooks and the direction of
traction wires determines the point of application andtraction wires determines the point of application and
line of action of applied forces relative to its center ofline of action of applied forces relative to its center of
mass.mass.

MIDFACE DISTRACTIONMIDFACE DISTRACTION
 In 1993In 1993 ,at Scottish Rite Chidren’s medical Centre,,at Scottish Rite Chidren’s medical Centre,Steven Cohen etSteven Cohen et
alal performed a buried midface distraction in a child withperformed a buried midface distraction in a child with
anophthalmia and left craniofacial microsomia.Cephalograms andanophthalmia and left craniofacial microsomia.Cephalograms and
three dimensional computed tomographic scans,showed excellentthree dimensional computed tomographic scans,showed excellent
results.results.
 Later in 1994 and early 1995 Cohen et al performed buried modifiedLater in 1994 and early 1995 Cohen et al performed buried modified
Le Fort III midface advancement in two children who had cleft lipLe Fort III midface advancement in two children who had cleft lip
and palate with midface hypoplasia and Class III malocclusion.and palate with midface hypoplasia and Class III malocclusion.
 In each case transverse maxillary expansion was performedIn each case transverse maxillary expansion was performed
simultaneously with sagittal distraction and in one case serialsimultaneously with sagittal distraction and in one case serial
distractors were used to provide both vertical and horizontaldistractors were used to provide both vertical and horizontal
distraction vectors.distraction vectors.
 This represented the first case of multidirectional midfaceThis represented the first case of multidirectional midface
distraction.In 1996,using specially designed buried midfacedistraction.In 1996,using specially designed buried midface
distraction devices Cohen et al performed a subtotal cranial vaultdistraction devices Cohen et al performed a subtotal cranial vault
reshaping and monobloc facial advancement in a child who hadreshaping and monobloc facial advancement in a child who had
Pfieffer’s syndrome and corneal exposure.Pfieffer’s syndrome and corneal exposure.www.indiandentalacademy.com

 In 1997,in the journal of Craniofacial Surgery,In 1997,in the journal of Craniofacial Surgery, Polley and FigueroaPolley and Figueroa
discussed the management of severe maxillary deficiency indiscussed the management of severe maxillary deficiency in
childhood and adolescence,performing distraction osteogenesis withchildhood and adolescence,performing distraction osteogenesis with
an external adjustable,Rigid Distraction Device.an external adjustable,Rigid Distraction Device.
 Their results in patients with cleft lip and palate and severe midfaceTheir results in patients with cleft lip and palate and severe midface
retrusion were impressive.retrusion were impressive.
 The Modular Internal Distraction (MID)system allows the surgeonThe Modular Internal Distraction (MID)system allows the surgeon
to fabricate custom internal distraction devices for virtually anyto fabricate custom internal distraction devices for virtually any
region of the craniofacial skeleton.region of the craniofacial skeleton.
 The first generation system contains expansion screws capable of 15The first generation system contains expansion screws capable of 15
mm to 30 mm of distraction.mm to 30 mm of distraction.
 Depending on the distraction site and osteotomy, any configurationDepending on the distraction site and osteotomy, any configuration
of titanium plates can be attached to the distraction screw to permitof titanium plates can be attached to the distraction screw to permit
uniplanar and possibly biplanar internal distraction.uniplanar and possibly biplanar internal distraction.
 A flexible activation cable is brought out through a distant,A flexible activation cable is brought out through a distant,
inconspicuous stab wound in the hair behind the ear.inconspicuous stab wound in the hair behind the ear.

CLINICAL INDICATIONSCLINICAL INDICATIONS
 When patients with Cleft lip and palate and severe midfaceWhen patients with Cleft lip and palate and severe midface
retrusion are present at the age of 6 years, distractionretrusion are present at the age of 6 years, distraction
osteogenesis can be used in combination with early rapidosteogenesis can be used in combination with early rapid
palatal expansion to correct both sagittal and transversepalatal expansion to correct both sagittal and transverse
maxillary deficiencies.maxillary deficiencies.
 Because internal devices require a second operation forBecause internal devices require a second operation for
removal, the treatment plan ofremoval, the treatment plan of Cohen et alCohen et al in chidren within chidren with
cleft lip and palate has centered around the timing ofcleft lip and palate has centered around the timing of
alveolar bone grafting.alveolar bone grafting.
 Simultaneous with distraction,a palatal expander is placedSimultaneous with distraction,a palatal expander is placed
and, if possible, orthodontic appliances are applied.and, if possible, orthodontic appliances are applied.
 A high Le Fort I osteotomy is performed and distractionA high Le Fort I osteotomy is performed and distraction
devices are placed intraorally.devices are placed intraorally.
 The distraction device is placed completely within theThe distraction device is placed completely within the
maxilla through an upper buccal sulcus incisionmaxilla through an upper buccal sulcus incision

 If there is insufficient room for fixation of the posterior plate,aIf there is insufficient room for fixation of the posterior plate,a
temporal incision can be made and the plate anchored to the temporaltemporal incision can be made and the plate anchored to the temporal
bone.bone.
 The distraction vector can be varied from horizontal to oblique toThe distraction vector can be varied from horizontal to oblique to
provide both vertical and horizontal distraction vectors. Cohen et alprovide both vertical and horizontal distraction vectors. Cohen et al
prefers to use orthodontic appliances with surgical hooks,as well asprefers to use orthodontic appliances with surgical hooks,as well as
hooks attached to the molar bands,for application of both dentalhooks attached to the molar bands,for application of both dental
elastics and reverse headgear in the event thatelastics and reverse headgear in the event that
 Distraction with internal devices cannot be technically performedDistraction with internal devices cannot be technically performed
 After distraction,additional stabilization and maintainance are required.After distraction,additional stabilization and maintainance are required.
 The newly formed bone undergoes a consolidation period of 2 to 3The newly formed bone undergoes a consolidation period of 2 to 3
months.months.
 Because the devices are internal and the activation cables are largelyBecause the devices are internal and the activation cables are largely
hidden in the hair,patients are quite comfortable during thehidden in the hair,patients are quite comfortable during the
consolidation phase.consolidation phase.
 At the time of bone removal,alveolar bone grafting is performed withAt the time of bone removal,alveolar bone grafting is performed with
iliac boneiliac bone

 Conventional monobloc osteotomies produce an immediateConventional monobloc osteotomies produce an immediate
retrofrontal dead space,which fills with blood and is prone toretrofrontal dead space,which fills with blood and is prone to
infection.infection.
 When distraction osteogenesis is used for monoblocWhen distraction osteogenesis is used for monobloc
osteotomy,the frontofacial segment is mobilized,but notosteotomy,the frontofacial segment is mobilized,but not
advanced.advanced.
 Beginning on days 5 through 7 ,distraction devices areBeginning on days 5 through 7 ,distraction devices are
activated 1 mm per day.activated 1 mm per day.
 This latency period seems to permit remucosalisation of theThis latency period seems to permit remucosalisation of the
nasofrontal area.nasofrontal area.
 Also, gradual distraction is not associated with theAlso, gradual distraction is not associated with the
development of an immediate retrofrontal dead space,whichdevelopment of an immediate retrofrontal dead space,which
is prone to infection.is prone to infection.
 Other possible indications for midface distraction includeOther possible indications for midface distraction include
 Correction of maxillary canting in hemifacial microsomia andCorrection of maxillary canting in hemifacial microsomia and
other asymmetry malformationsother asymmetry malformations
 Apnea with associated midface retrusionApnea with associated midface retrusion
 Treacher Collins syndrome for zygomatic advancementTreacher Collins syndrome for zygomatic advancement
 Midface retrusion of any cause,depending on severity.Midface retrusion of any cause,depending on severity.www.indiandentalacademy.com

TIMING OF SURGERYTIMING OF SURGERY
 Addition of distraction osteogenesis to the surgicalAddition of distraction osteogenesis to the surgical
armamentarium has altered timings of surgical interventions.armamentarium has altered timings of surgical interventions.
 In children with syndromic craniosynostosis and severeIn children with syndromic craniosynostosis and severe
midface retrusion,monobloc osteotomies can be performedmidface retrusion,monobloc osteotomies can be performed
safely at younger than 1 year of age.safely at younger than 1 year of age.
 Overcorrection of the deformity may also eliminate the needOvercorrection of the deformity may also eliminate the need
for some future surgeries.In chidren age 4 to 7 yearsfor some future surgeries.In chidren age 4 to 7 years
undergoing monobloc or Le Fort III subcranial osteotomy,undergoing monobloc or Le Fort III subcranial osteotomy,
operative morbidity is also reduced.operative morbidity is also reduced.
 According to Cohen et al distraction should be performedAccording to Cohen et al distraction should be performed
at 6 years of age to correct severe midface retrusion inat 6 years of age to correct severe midface retrusion in
patients with cleft lip and palate.patients with cleft lip and palate.
 Distraction can be used in older children with cleft lip andDistraction can be used in older children with cleft lip and
palate, midface retrusion and severe Class III dentoskeletalpalate, midface retrusion and severe Class III dentoskeletal
relations.relations.

TREATMENT PLANNINGTREATMENT PLANNING
 A surgical and orthodontic work up is necessary to develop theA surgical and orthodontic work up is necessary to develop the
appropriate treatment plan.appropriate treatment plan.
 Clinical photographs,computed tomographic scans,clinicalClinical photographs,computed tomographic scans,clinical
orthodontic and surgical evaluation and orthodontic recordsorthodontic and surgical evaluation and orthodontic records
including cephalometric interpretation and mounted casts areincluding cephalometric interpretation and mounted casts are
obtained.obtained.
 Speech evaluation is obtained preoperatively and after removalSpeech evaluation is obtained preoperatively and after removal
of the distraction device because patients undergoing midfaceof the distraction device because patients undergoing midface
distraction are at risk for developing velopharyngealdistraction are at risk for developing velopharyngeal
insufficiency.insufficiency.
 Special consideration is given to the dentition and the ability toSpecial consideration is given to the dentition and the ability to
place orthodontic appliance.place orthodontic appliance.
 In children undergoing midface distraction, ideally an acrylic biteIn children undergoing midface distraction, ideally an acrylic bite
block attached to the mandible can be used to simulate theblock attached to the mandible can be used to simulate the
increased vertical dimensions of the maxilla that will occur withincreased vertical dimensions of the maxilla that will occur with
distractiondistraction

 By repositioning mandible in this fashion the muscles ofBy repositioning mandible in this fashion the muscles of
mastication are retrained at the anticipated new vertical maxillarymastication are retrained at the anticipated new vertical maxillary
dimension.dimension.
 Orthodontic appliances are attached to the teeth.Surgical hooksOrthodontic appliances are attached to the teeth.Surgical hooks
are incorporated on at least the anterior dentition.are incorporated on at least the anterior dentition.
 In addition, hooks are placed on the molar bands for applicationIn addition, hooks are placed on the molar bands for application
of reverse headgear, if internal distraction cannot be performedof reverse headgear, if internal distraction cannot be performed
or for retention at the conclusion of distraction.or for retention at the conclusion of distraction.
 When orthodontic appliances cannot be placed,arch bars areWhen orthodontic appliances cannot be placed,arch bars are
ligated to the dentition with the assistance of piriformligated to the dentition with the assistance of piriform
suspension and circummandibular wires.suspension and circummandibular wires.
 In patients who develop an open bite deformity, dental elasticsIn patients who develop an open bite deformity, dental elastics
can be placed at the conclusion of distraction, but beforecan be placed at the conclusion of distraction, but before
consolidation, to manipulate the callus and close the anteriorconsolidation, to manipulate the callus and close the anterior
open bite.open bite.
 Patients in whom dental midline rotates during distraction canPatients in whom dental midline rotates during distraction can
also be corrected simultaneously with elastics beforealso be corrected simultaneously with elastics before
consolidationconsolidation

SURGICAL TECHNIQUESSURGICAL TECHNIQUES
LE FORT I DISTRACTIONLE FORT I DISTRACTION
 The LeFort I osteotomy is performed in a stair step fashionThe LeFort I osteotomy is performed in a stair step fashion
to provide adequate posterior bone for attachment of theto provide adequate posterior bone for attachment of the
distraction device.distraction device.
 Because the MID system provides flexibility,Because the MID system provides flexibility,
the types of titanium plates selected forthe types of titanium plates selected for
posterior and anterior distraction vary.posterior and anterior distraction vary.

 To maintain a direct sagittal distraction vector, theTo maintain a direct sagittal distraction vector, the
anterior plate is generally bent with a step.anterior plate is generally bent with a step.
 In patients with insufficient maxillary bone, it may beIn patients with insufficient maxillary bone, it may be
necessary to attach the posterior plate to the temporalnecessary to attach the posterior plate to the temporal
bone.bone.
 This is done by simply making a temporal incision andThis is done by simply making a temporal incision and
retrieving the plate from below.retrieving the plate from below.
 Cohen et al believes it is necessary to make a completeCohen et al believes it is necessary to make a complete
osteotomy and ,therefore the osteotomy is kept justosteotomy and ,therefore the osteotomy is kept just
below the level of the inferior orbital foramen andbelow the level of the inferior orbital foramen and
nerve.nerve.
 In this manner the erupting dentition is also avoided.In this manner the erupting dentition is also avoided.

LE FORT III DISTRACTIONLE FORT III DISTRACTION
 A standard Le Fort III osteotomy is performed. InA standard Le Fort III osteotomy is performed. In
younger children who are at risk for fracturing theyounger children who are at risk for fracturing the
zygomatic-maxillary suture region, the anterior plate iszygomatic-maxillary suture region, the anterior plate is
configurated and rigidly fixed after the osteotomy, butconfigurated and rigidly fixed after the osteotomy, but
before downfracture.before downfracture.
 In this fashion, inadvertent fracture across the zygomatic-In this fashion, inadvertent fracture across the zygomatic-
maxillary suture is prevented.maxillary suture is prevented.

 The anterior plate wraps around the malar eminenceThe anterior plate wraps around the malar eminence
and extends along the inferior orbital rim.and extends along the inferior orbital rim.
 The anterior plate also is attached along the lateralThe anterior plate also is attached along the lateral
orbital rim and superiorly.orbital rim and superiorly.
 The posterior plate is stabilized to the temporal boneThe posterior plate is stabilized to the temporal bone
underneath the temporal muscleunderneath the temporal muscle
 A 30 mm distraction frame is chosen and attached toA 30 mm distraction frame is chosen and attached to
the anterior and posterior plates.the anterior and posterior plates.
 A flexible cable is brought through a stab woundA flexible cable is brought through a stab wound
posterior to the coronal incision.posterior to the coronal incision.
 In Le Fort III osteotomy ,typically 2 mm to 4 mm ofIn Le Fort III osteotomy ,typically 2 mm to 4 mm of
distraction is performed in the operating room.distraction is performed in the operating room.

 Distraction is then begun on the fifth postoperative dayDistraction is then begun on the fifth postoperative day
at a rate of 1 mm per day.at a rate of 1 mm per day.
 Once the appropriate porion to orbitale distance hasOnce the appropriate porion to orbitale distance has
been reached or mild enophthalmos has been producedbeen reached or mild enophthalmos has been produced
with overcorrection of the malocclusion, distraction iswith overcorrection of the malocclusion, distraction is
stopped and the distraction gap allowed to consolidatestopped and the distraction gap allowed to consolidate
over a period of 2 months.over a period of 2 months.
 Lateral and posteroanterior cephalograms are taken toLateral and posteroanterior cephalograms are taken to
ensure that the distraction device has openedensure that the distraction device has opened
symmetrically.symmetrically.
 At the conclusion of distraction dental elastics are usedAt the conclusion of distraction dental elastics are used
to correct occlusal abnormalities.to correct occlusal abnormalities.
 After the consolidation period, the devices are removed.After the consolidation period, the devices are removed.

MONOBLOC DISTRACTIONMONOBLOC DISTRACTION
(FRONTO-ORBITAL-FACIAL ADVANCEMENT)(FRONTO-ORBITAL-FACIAL ADVANCEMENT)
 Monobloc distraction is applicable in children aged youngerMonobloc distraction is applicable in children aged younger
than 1 year ,but can be used in any age group.than 1 year ,but can be used in any age group.
 A bilateral coronal incision with elevation of the anterior scalpA bilateral coronal incision with elevation of the anterior scalp
flap was performed.flap was performed.
 Dissection was extended in a subperiosteal plane over theDissection was extended in a subperiosteal plane over the
midforehead region and in a superior,lateral and medial directionmidforehead region and in a superior,lateral and medial direction
around the orbits, and continued deep to the superficial layer ofaround the orbits, and continued deep to the superficial layer of
the deep temporal fascia, exposing the zygomatic arches laterallythe deep temporal fascia, exposing the zygomatic arches laterally
and the anterior maxilla.and the anterior maxilla.
 Through a subciliary incision of the lower lids,exposure wasThrough a subciliary incision of the lower lids,exposure was
obtained of the inferior orbital rim and the medial orbital wall.obtained of the inferior orbital rim and the medial orbital wall.
 Subperosteal mobilization of the orbital contents was completed.Subperosteal mobilization of the orbital contents was completed.

 A bifrontal craniotomy was performed with seperation ofA bifrontal craniotomy was performed with seperation of
the cranial bones from the dura;the zygomatic archesthe cranial bones from the dura;the zygomatic arches
were divided and a circular orbitotomy ensued.were divided and a circular orbitotomy ensued.
 Separation of the bony nasal septum from the anteriorSeparation of the bony nasal septum from the anterior
cranial base,seperation of the pterygomaxillary junctioncranial base,seperation of the pterygomaxillary junction
and midface advancement were performed.and midface advancement were performed.

 The main advantage of midface distraction appears to beThe main advantage of midface distraction appears to be
the reduction of infectious complications.the reduction of infectious complications.
 Children tolerate distraction extremely well and typicallyChildren tolerate distraction extremely well and typically
require postoperative ventilation for only one day.require postoperative ventilation for only one day.
 Distraction is begun on the fifth postoperative day.Distraction is begun on the fifth postoperative day.
 In contrast to Le Fort III distraction technique, noIn contrast to Le Fort III distraction technique, no
advancement is performed in the operating room Afteradvancement is performed in the operating room After
the nasofrontal region has been allowed to remucosalise,the nasofrontal region has been allowed to remucosalise,
distraction is initiated at 1 mm per day.distraction is initiated at 1 mm per day.
 The cranial defect produced by the advancing monoblocThe cranial defect produced by the advancing monobloc
segment can be palpated to determine when consolidationsegment can be palpated to determine when consolidation
has been completedhas been completed

MANDIBULAR DISTRACTIONMANDIBULAR DISTRACTION
 Mandibular distraction is a safe and effective surgicalMandibular distraction is a safe and effective surgical
technique. For patients withtechnique. For patients with Treacher Collins, PierreTreacher Collins, Pierre
Robin, NagerRobin, Nager andand Craniofacial microsomia syndromesCraniofacial microsomia syndromes
undergoing surgical reconstruction of the hypoplasticundergoing surgical reconstruction of the hypoplastic
mandible by distraction, the length of hospitalization andmandible by distraction, the length of hospitalization and
operating time has been drastically reduced.operating time has been drastically reduced.
 It has obviated the need forIt has obviated the need for
autogenous bone grafting andautogenous bone grafting and
because of the expansion of thebecause of the expansion of the
associated soft tissues, there is aassociated soft tissues, there is a
resulting multidirectional expansionresulting multidirectional expansion
of the skeletal and soft tissue envelope.of the skeletal and soft tissue envelope.

 Patients with mandibular growth disturbances can presentPatients with mandibular growth disturbances can present
at any age.at any age.
 If the patient is under 2 years of age, mandibularIf the patient is under 2 years of age, mandibular
distraction is not usually performed .distraction is not usually performed .
 Soft tissue treatments such as cleft closure or preauricularSoft tissue treatments such as cleft closure or preauricular
skin tag removal ,are initiated. Cranial vault remodelingskin tag removal ,are initiated. Cranial vault remodeling
procedures are also performed at this age.procedures are also performed at this age.
 Mandibular surgery is avoided for several reasons-Mandibular surgery is avoided for several reasons-
 It is difficult to identify tooth buds at this age ,thereforeIt is difficult to identify tooth buds at this age ,therefore
permanent dental injury is a likely occurance.permanent dental injury is a likely occurance.
 The bone stock is soft,making satisfactory fixation of theThe bone stock is soft,making satisfactory fixation of the
distraction apparatus difficult and loss of device(because of pindistraction apparatus difficult and loss of device(because of pin
loosening ) a strong possibility.loosening ) a strong possibility.
 Distraction at this age can be a daunting experience for theDistraction at this age can be a daunting experience for the
patient and the parents.patient and the parents.

 From the age of 2 to 6 years,mandibular distractionFrom the age of 2 to 6 years,mandibular distraction
osteogenesis can be considered in severe conditions withosteogenesis can be considered in severe conditions with
associated sleep apnea or tracheostomy.associated sleep apnea or tracheostomy.
 However if distraction occurs at this age interval,it is likelyHowever if distraction occurs at this age interval,it is likely
that a secondary distraction will be required after postthat a secondary distraction will be required after post
pubertal facial growth, because it is unlikely that thepubertal facial growth, because it is unlikely that the
mandibular development will keep up with the growth ofmandibular development will keep up with the growth of
the remainder of the facial skeleton.the remainder of the facial skeleton.
 Mandibular distraction during the teenaged years shouldMandibular distraction during the teenaged years should
be post poned until the patient has reached skeletalbe post poned until the patient has reached skeletal
maturity.maturity.
 In girls, this typically occurs around 15 years of age and inIn girls, this typically occurs around 15 years of age and in
boys around the age of 17 years.boys around the age of 17 years.

Indications for surgery in the teen years includeIndications for surgery in the teen years include
 Residual postsurgical relapse or abnormal growthResidual postsurgical relapse or abnormal growth
 unsatisfactory bone contourunsatisfactory bone contour
 MalocclusionMalocclusion
 In patients with minimal mandibular deformities, classicIn patients with minimal mandibular deformities, classic
orthognathic procedures are indicated.orthognathic procedures are indicated.
 Mandibular distraction should be considered in patientsMandibular distraction should be considered in patients
with moderate to severe skeletal deficiency or bilateralwith moderate to severe skeletal deficiency or bilateral
disease in whom pressure from the soft tissues woulddisease in whom pressure from the soft tissues would
significantly increase the risk for post operative graftsignificantly increase the risk for post operative graft
resorption or relapse of bony fixation.resorption or relapse of bony fixation.

PREOPERATIVE CLINICAL EVALUATIONPREOPERATIVE CLINICAL EVALUATION
 The patient should be examined with the head in an uprightThe patient should be examined with the head in an upright
position and submental vertex position.position and submental vertex position.
 In patients with unilateral craniofacial microsomia,the position ofIn patients with unilateral craniofacial microsomia,the position of
the oral commissure should be documented,and the distancethe oral commissure should be documented,and the distance
between it and the external auditory canal recorded.between it and the external auditory canal recorded.
 The position and contour of the chin ,inferior border,and angle ofThe position and contour of the chin ,inferior border,and angle of
the mandible are recorded.the mandible are recorded.
 In intraoral examination the occlusal planeIn intraoral examination the occlusal plane
or transverse cant should be related to theor transverse cant should be related to the
transorbital plane.transorbital plane.

 The functional clinical examination shouldThe functional clinical examination should
include documentation of mandibularinclude documentation of mandibular
excursions, including maximum interincisalexcursions, including maximum interincisal
opening, because a transient limitation toopening, because a transient limitation to
opening can occur at the end of distraction.opening can occur at the end of distraction.
 It is, therefore, important to record the originalIt is, therefore, important to record the original
interincisal opening for use as an objective goalinterincisal opening for use as an objective goal
during postdistraction physical therapy.during postdistraction physical therapy.
 The function of TMJ is documented,and theThe function of TMJ is documented,and the
motor and sensory nerve functions are recordedmotor and sensory nerve functions are recorded

DIAGNOSTIC RECORDSDIAGNOSTIC RECORDS
 Cranial pathology and asymmetry should be documented byCranial pathology and asymmetry should be documented by
standard medical photographs.Lateral and posteroanteriorstandard medical photographs.Lateral and posteroanterior
cephalograms with the head in the correct vertical or midsagittalcephalograms with the head in the correct vertical or midsagittal
plane is obtained.plane is obtained.
 The ear rod is positioned in the ear canal on the unaffected side butThe ear rod is positioned in the ear canal on the unaffected side but
is placed on the calvaria on the affected side.is placed on the calvaria on the affected side.
 Midsagittal plane is perrendicular to the floor and the lateralMidsagittal plane is perrendicular to the floor and the lateral
borders of the orbital rims are symmetrically positioned in relationborders of the orbital rims are symmetrically positioned in relation
to the lateral borders of the calvarium.to the lateral borders of the calvarium.
 This precise head positioning is duplicated inThis precise head positioning is duplicated in
all subsequent recordings.In addition a threeall subsequent recordings.In addition a three
diamentional computed tomographic scan,diamentional computed tomographic scan,
panoramic roentgenogram and dental studypanoramic roentgenogram and dental study
models are made.models are made.

TECHNIQUETECHNIQUE
 Patients who require unidirectional lenghthening and have adequatePatients who require unidirectional lenghthening and have adequate
mandibular bone stock are candidates for intraoral distraction.mandibular bone stock are candidates for intraoral distraction.
 Patients in whom mandibular deficiency is more severe and who alsoPatients in whom mandibular deficiency is more severe and who also
require distraction in the vertical and horizontal dimensions are bestrequire distraction in the vertical and horizontal dimensions are best
treated with an extraoral device.treated with an extraoral device.
 In addition,patients who have previous external scars from otherIn addition,patients who have previous external scars from other
procedures are treated with an extraoral device.The intraoral mucosalprocedures are treated with an extraoral device.The intraoral mucosal
incision along the oblique line of the ramus is used for placement ofincision along the oblique line of the ramus is used for placement of
both intra oral and extra oral devices.both intra oral and extra oral devices.
 Currently, subperiosteal dissection is used to elevate the entire lateralCurrently, subperiosteal dissection is used to elevate the entire lateral
periosteal surface with a sharp ended elevator.periosteal surface with a sharp ended elevator.
 After the region of the osteotomy is exposed, the reciprocating sawAfter the region of the osteotomy is exposed, the reciprocating saw
is used to create lateral,anterior and posterior corticotomies.is used to create lateral,anterior and posterior corticotomies.
 Before converting the corticotomies into an osteotomy,the pins areBefore converting the corticotomies into an osteotomy,the pins are
placed.placed.

 If the intraoral device is used,a single percutaneous stabIf the intraoral device is used,a single percutaneous stab
incision is made for the placement of the screwdriver.incision is made for the placement of the screwdriver.
 For the extraoral device,a two-holed trocar is used forFor the extraoral device,a two-holed trocar is used for
percutaneous placement of the posterior pins.percutaneous placement of the posterior pins.
 The second anterior pair of pins is placed so that the skinThe second anterior pair of pins is placed so that the skin
between the two pin sites is compressed,thereby reducingbetween the two pin sites is compressed,thereby reducing
the amount of tension on the wound and the length ofthe amount of tension on the wound and the length of
the scar.the scar.
 The device is attached to the pins.The device is attached to the pins.
 A 3 mm osteotome completes the medial wall osteotomyA 3 mm osteotome completes the medial wall osteotomy
, liberating the mandibular segments for distraction., liberating the mandibular segments for distraction.
 The wounds are closed in layers with absorbable sutures.The wounds are closed in layers with absorbable sutures.

 A careful cleaning regimen is followed in which the pin tracks areA careful cleaning regimen is followed in which the pin tracks are
cleaned four times a day,and as needed,of any blood or serouscleaned four times a day,and as needed,of any blood or serous
discharge.discharge.
 After aAfter a latency periodlatency period ofof 5 to 75 to 7 daysdays ,distraction commences at a rate,distraction commences at a rate
of 0.5 mm twice a day.of 0.5 mm twice a day.
 This rate is continued until the mandibular length is overcorrected byThis rate is continued until the mandibular length is overcorrected by
several millimeters.several millimeters.
 Orthodontic intermaxillary elastics may be used to mold theOrthodontic intermaxillary elastics may be used to mold the
regenerating new bone and optimize the occlusion.regenerating new bone and optimize the occlusion.
 The device is left in place to serve as an external fixator forThe device is left in place to serve as an external fixator for 8 or more8 or more
weeksweeks, until there is radiographic evidence of mineralisation.This stage, until there is radiographic evidence of mineralisation.This stage
is known as theis known as the consolidationconsolidation phase.phase.
 In patients with unilateral craniofacial microsomia undergoingIn patients with unilateral craniofacial microsomia undergoing
distraction,it is important that a dental impression be taken and a bitedistraction,it is important that a dental impression be taken and a bite
block placed in the surgically created posterior open bite when theblock placed in the surgically created posterior open bite when the
device is removed.device is removed.
 This will allow the orthodontist to level the maxillary occlusal plane byThis will allow the orthodontist to level the maxillary occlusal plane by
allowing for eruption of the ipsilateral maxillary dento alveolarallowing for eruption of the ipsilateral maxillary dento alveolar
complex.complex.

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