Distraction osteogenesis (8)

DISTRACTION
OSTEOGENESIS
www.indiandentalacademy.com

-INTRODUCTION
-HISTORICAL REVIEW
-ILIZAROV PRINCIPLES
- D O IN CRANIOFACIAL REGION
-MERITS OF D O
-DEMERITS OF D O
- INDICATIONS
-CONTRAINDICATIONS
-BIOLOGIC BASIS OF D O
- ORTHODONTIC TOOTH MOVEMENT INTO DISTRACTED BONE
-IMPLANT PLACEMENT IN DISTRACTED BONE
-BIOMECHANICAL EFFECTS OF DEVICE PLACEMENT
-DEVICE SELECTION
-VECTOR ORIENTATION
-CLASSIFICATION OF REGENERATE BONE
-D O OF MANDIBLE ,MAXILLA ,MIDFACE , CRANIOFACIAL SKELETON
-PERIDONTAL DISTRACTION
-EFFECTS OF D O on T M J
-POTENTIAL MISTAKES
-COMPLICATIONS
-CONCLUSION
-REFERENCES www.indiandentalacademy.com

INTRODUCTION
For centuries many different techniques have been used in an attempt to
modify growth ,both in terms of amount and direction .Orthodontists for
example ,use intra oral and extra oral appliances to restrict growth of the
maxilla in hope of accentuating mandibular saggital growth .
Recently , a new technique of bone generation and reconstruction , termed
Distraction Osteogenesis was introduced to clinicians of craniofacial
region by orthopedic surgeons.

Distraction osteogenesis is the biologic process of new bone
formation between bone segments gradually separated by
incremental traction .This process begins when a distraction
force is applied to the healing callus that joins the divided bone
segments and continues as long as the tissue is stretched .It is of
importance in cases where the traditional orthognathic
procedures are found wanting to correct the growth deficiencies
yielding unstable results and subsequent relapse. Bone is
required for a variety of purposes –traumatic loss, tumor
resection ,congenital deformities. The challenges that arise in
craniofacial surgery due to inadequate bone volume or bone
defects have led to many attempts at solutions in the past.
CALLOTASIS --
Latin noun CALLUM-Scar tissue between bone segments
Greek noun TAOIS –tension or extension

Distraction force applied to bone also creates tension in the
surrounding soft tissues ,initiating a sequence of adaptive
changes termed distraction Histogenesis.Under influence of
tensional stresses produced by gradual distraction ,active
histogenesis occurs in different tissues including skin ,fascia,
tendon ,muscle ,cartilage, blood vessels ,peripheral nerves.

Historical review –Early forms of bone manipulation -
Hippocrates more than 2000 years
ago described the placement of
traction forces on broken bones.
Guy de Chauliac in 14th
century
applied traction with a pulley
system that consisted of a
weight attached to the leg by a
chord .the weight was
suspended over a pulley to
create tension.
John Barton in 1826 was the first to
perform surgical division of bone
or osteotomy .
Joseph Malgaigne constructed an
apparatus for external fixation of
displaced transverse patellar
fractures.

Early Techniques for Distraction Osteogenesis –
At the turn of 20th
century
ALESSANDRO CODIVILLA first
performed limb lengthening using
external skeletal traction after an
oblique osteotomy of the femur,
later several surgeons modernized
CODIVILLAS continuous extension
procedure by modifying the
osteotomy technique the distraction
protocol or the device for bone
fixation .
Paul Magnuson recognized the biologic
potential of periosteum and
endosteum .
Vittorio Putti designed the osteoton ,for
femur lengthening .

Refinements of Distraction Osteogenesis Procedures .
Summaries soon appeared reporting success
and complication during limb lengthening.
The complications included delayed healing ,
non unions ,deformities ,nerve palsy,and joint
contracture . This prevented widespread
acceptance of distraction osteognesis and
required further improvements in osteotomy
techniques ,distraction protocol ,appliance
design.
A significant contribution in the development of
DO was made by the Russian surgeon
,GAVRIEL ILIZAROV .IN 1951 .He designed
a new apparatus for bone .fixation .
This fixation technique has two distinct
advantages over other methods ,
Stable but not rigid fixation to provide axial micro
movements
Full control over the manipulation of bone
segments ,regardless of their size shape or
anatomic location
ILIZAROV divided 2/3 rd of bony cortex with a
narrow osteotome and completed the
corticotomy by rotational osteoclasis , there
by causing minimal trauma to the periosteum
and bone marrow . His lengthening protocol
utilized a 5-7 day latency period followed by a
distraction of 1 mm per day performed in
four increments of 0.25 mm.

Based on his clinical experience ,ILIZAROV discovered biologic
principles of Distraction Osteogenesis,known as the ILIZAROV effects
1)The tension stress effect on the genesis and growth of tissues
2)the influence of blood supply and loading on the shape of bones and
joints
The third group of expts – the effect of the distraction on the orientation
of newly formed tissues .He discovered that the regenerate within the
distraction gap is always formed along the axis of applied traction.
The next set of expts- the influences of the rate and rhythm of distraction
on the formation of bone regenerate. Results proved that more frequent
rates of distraction ,more favorable regenerate formation and cause fewer
soft tissue problems

The last study looked at the relationship between blood supply and mechanical loading and its
influence upon the shape and mass of the resulting bone .ILIZAROV stated that in order to
maintain function the blood supply must be proportional to the mechanical load .
D O IN CRANIOFACIAL COMPLEX
In 1976 BELL and EPKER – RPE in patients with transverse deficiency .
Osteo distraction of mandibular symphysis using principles of RPE was initially reported by
Gurerro in 1990.
IN 1992 Mc CARTHY reported results of clinical applications of Distraction Osteogenesis in
patients with congenital cranio facial anomalies .Following the reports of Mc Carthy which
demonstrated successful lengthening of human mandible by gradual bone distraction heralded
the beginning of craniofacial distraction

MERITS OF DISTRACTION OSTEOGENESIS
-Relatively simple operative technique
-Lengthening of bone and soft tissues
-Good long term stability
-Avoidance of bone grafts
-Multidimensional distraction
-Feasible to distract bone grafts or irradiated bone
-Results are apparently early
-Reduces likelihood of relapse
-Reduces likelihood of blood transfusion
DRAWBACKS OF DISTRACTION OSTEOGENESIS
-Skin scars with extra oral devices
-Damage to Facial nerve
-Damage To Tooth Germ
-Premature consolidation
-Transient changes in TMJ
-Infection
-Nonunion/inadequate bone formation
-Device failure

CLASSIFICATION OF TREATMENT MODALITIES WITH D O
D O in the field of craniofacial reconstruction is applicable for the following 6 Rx
techniques
1) To lengthen the mandible
2) To advance the maxilla /midface or monobloc advancement
3) Bone segment transportation
4) Trifocal distraction treatment as in case of symphyseal defect
5) Distraction for alveolar augmentation
6) Distraction implantology

MANDIBULAR DISTRACTION OSTEOGENESIS
Indications
-Hemifacial Microsomia
-Treacher Collin Syndrome
-Congenital Micrognathia
- Nager Syndrome
-Pierre Robin Syndrome
-Goldenhar Syndrome
-Moebius Syndrome
- Facial Cleft
-Cranio Facial Microsomia
-Trauma ,Pathologic defect
-Alveolar defect
-Transverse defect
-Alveolar augmentation
MAXILLARY DISTRACTION OSTEOGENESIS
INDICATIONS
-Orofacial clefts
-Nasomaxillary dysplasia
-Cranio synostosis
-Maxillary atrophy
-Alveolar augmentation

MIDFACIAL AND /OR CRANIAL DISTRACTION
INDICATIONS
=Craniosynostosis
-Crouzon syndrome
-Aperts syndrome
-Sagittal synostosis
-Midfacial cleft
SIMULTANEOUS MANDIBULAR AND MAXILLARY DISTRACTION
OSTEOGENESIS
INDICATIONS
-Hemi facial Microsomia
=Treacher Collins syndrome
CONTRAINDICATIONS OF DISTRACTION OSTEOGENESIS
-Insufficient quantity or quality of bone which would inhibit fixation of the device such as
osteoporosis
-Inability to comply with the post operative distraction regimen and follow up schedule
-Hypersensitivity to metals
-Infection
-Neuro psychiatric disorders
-Immuno suppression

SELECTION OF PATIENT FOR DISTRACTION OSTEOGENESIS
-Age of the patient
-Severity of the anatomical malformations which can affect the soft tissues
-Potential for bone growth depending on the etiology
-Functional and esthetic effects
-Secondary malformations
-Psychological considerations
BASIC PRINCIPLES OF DISTRACTION OSTEOGENESIS
-Preservation of blood supply
-Close apposition of cut bone surfaces to allow early bridge formation
-Gradual distraction at regular rhythm.
RATE OF DISTRACTION – number of millimeters per day at which the bone
surfaces are stretched . The rate of 1mm a day is considered optimal.
RHYTHM OF DISTRACTION – number of distractions per day usually in equally
divided increments to total the rate. The rhythm may vary from one cycle per day
of 1mm to 0.025 mm four times per day or 0.5 mm twice daily .

BIOLOGIC BASIS OF DISTRACTION OSTEOGENESIS
D O begins with the formation of a reparative callus .Callus is placed under
tension by stretching which generates new bone .
D O consists of 3 sequential periods
1)LATENCY PERIOD –is the period from bone division to the onset of
traction and represents the time allowed for callus formation
2)DISTRACTION PERIOD –interval during which gradual traction is applied
and new bone or distraction regenerate is formed
3)CONSOLIDATION PERIOD –allows maturation and corticalization of the
regenerate after traction forces are discontinued .
LATENCY PERIOD –
consists of 4 stages and is comparable to that during fracture healing
1)inflammation 2)softcallus 3)hard callus 4)remodelling
Following the surgical separation of bone into 2 segments ,a cascade of
vascular disruption and extravasations of blood from the damaged bone ends
and the associated soft tissue ,a hematoma forms between and around the bone
segments .The hematoma is converted to a clot and bone necrosis occurs at the
ends of the fracture segments.
There is in growth of vasoformative elements and capillaries to restore blood
supply
clot is replaced by granulation tissue

During soft callus stage granulation tissue becomes fibrous
vascularity increases
mesenchymal stem cells within the callus appear inside the terminal of the newly
formed capillaries .
Cartilage replaces the granulation tissues.
This occurs more in the inter fragmentary space more towards the periphery
This fibro cartilaginous tissue is transformed into immature woven bone
The Cartilage calcifies as the capillaries invade the cartilage osteoblasts follow
and lay down new bone.
Woven Bone is converted to lamellar bone by a resorption replacement
sequence and the medullary canal is reconstituted .

DISTRACTION PERIOD
During D O normal process of fracture healing is disturbed
by application of gradual traction
Dynamic microenvironment
New tissue is formed in a direction parallel to the vector of
traction
Gradually stretched tissue promotes angiogenesis ,increase
tissue oxygenation and increased fibroblastic proliferation
Between 3rd
-7th
day of distraction capillaries grow into the
fibrous tissue and extends toward medullary cavity.
Newly formed vessels have a spiral pathway and numerous
circular folds suggesting growth rates 10 times higher than
rates of vessel growth during normal fracture healing during
two weeks of distraction primary osteons begin to form.
The osteoid producing osteoblasts located among the
collagen fibers lay down osteoid tissue on these collagen
fibers .
Osteogenesis is initiated at the existing bone walls and
progresses toward the center of the distraction gap by the
end of the second week the osteoid begins to mineralize.
The elongation of the regenerate depends on the growth of
primary osteons ,the length of which increases rapidly
during the early stages of distraction. www.indiandentalacademy.com

CONSOLIDATION PERIOD
After distraction ceases ,the fibrous inter zone gradually ossifies and one
distinct zone of woven bone completely bridges the gap
as the regenerate matures the zone of primary osteons significantly
decreases and is later completely resorbed .
Marrow cavity is restored
Haversian remodelling takes place
Maturation of distracted bone continues for a year or more before the
structure of newly formed bony tissue is comparable to that of the pre
existing bone
Radiographically the first evidence of bone regenerate is usually observed
at the end of the distraction period

MECHANISM OF NEW BONE FORMATION –
It appears that 3 different modes of bone formation occur during
Mandibular Distraction including Intramembranous ,Endochondral
,Transchondroid ossification . Although there is no direct evidence, we
consider that the cells involved in transchondroid bone formation
temporarily express cartilage tissue phenotype before differentiating
directly into osteocytes which survive in the chondroid tissue until it is
resorbed and remodelled into lamellar bone .The mechanism of new bone
formation is dependent on both blood supply and the rate of distraction.
The most appropriate rate of distraction is between 0.5 -1.0mm/day.

TOOTH MOVEMENT INTO REGENERATE BONE
Possibility of moving teeth into regenerate bone is no longer disputed however
the timing of initiating the tooth movement into newly created bone remains a
topic of discussion .
Gurerro ,Constasti ,Razdolsky ,Pensler ,Dessner – not until 8-12 weeks
Liou ,Chen ,Huang – begin much earlier in the consolidation period
Rather than basing clinical decisions on emperic supositions 3 Important
factors are to be considered
-Systemic Factors and Patients Health
-Tooth/Bone Related Factors
-Mechanical Factors
SYSTEMIC FACTORS – healing capacity , general health, blood supply ,
calcium balance ,bone quality
TOOTH BONE RELATED FACTORS –size shape of roots ,quantity of
surrounding bone ,amount of bone between osteotomy cut and root ,root surface
area
MECHANICAL FACTORS- type of force to initiate tooth movement –
tipping ,translatory ,intrusion ,extrusion .
Gingival fibers that might stretch during distraction there by applying forces to
teeth.

If little inter dental bone is left walking of tooth occurs before the regenerate is
mineralized enough to support .
Start with translatory force, this also adds up to the time taken for the
regenerate to mineralize
Start movement of the distal most tooth since many a times tooth distal to the
osteotomy is a molar.

PLACEMENT OF IMPLANT INTO DISTRACTED BONE
Sufficient osseointegration occurs with implants placed in the distraction
regenerate in the consolidation period ,this shortens the treatment duration .
The parallel columns of bone extending from the host margins were firm
enough to maintain the orientation of the implants .Prosthetic loading should
be delayed until 24 weeks.

BIOMECHANICAL EFFECTS OF DISTRACTION DEVICE
ORIENTATION DURING MANDIBULAR LENGTHENING AND
WIDENING
Mandible is a complex 3D STRUTURE consisting of two halves that are
fused in the midline at an acute angle .
V shaped Mandible- anatomic axis of the right and left sides are not
parallel to each other .

ORHTODONTICS IN INTRA ORAL MANDIBULAR DISTRACTION
OSTEOGENESIS
Careful Evaluation Of diagnostic records ---ideal treatment plan
Diagnostic Records include –
- detailed clinical examination
- cephalometric examination
- dental cast analysis
FACTORS To Be CONSIDERED –
Patients Age
Future Growth Potential
Oral hygiene
Plane of deformity
Amount of bone lengthening
Psychosocial status
Nutrition
General health
clinical examination –
mandibular sagital defeciency
convex facial profile
lip incopetance
large overjet
transverse dimensiosn
dark buccal corridors
v shaped arch. scissor bitewww.indiandentalacademy.com

CEHPALOMETRIC ANALYSIS
S T A
FRONTAL CEPHALOMETRIC ANALYSIS
DENTAL CAST ANALYSIS
OCCLUSOGRAM
Arch perimeter analysis
Boltons analysis
Flatten curve of spee

SAGITTAL MANDBULAR DISTRACTION OSTEOGENESIS
INDICATIONS
5 indications for distraction over orthognathic surgery
major mandibular advancements > 7mm
Pre surgical degenerative TMJdisease
Sleep apnoea
Inadeqate mandibular anatomy
Secondary mandibular advancements
PRE DISTRACTION ORTHODONTICS
Maxillary teeth are leveled and aligned, Ideal arch form developed
heavy rectangular surgical archwire with inter dental surgical hooks is placed
If there is no need for expansion mandibular archwire is placed
Pre surgical records are taken
Prediction surgery is then performed on casts
INTRA DISTRACTION AND POST DISTRACTION ORTHODONTICS
DISTRACTION DEVICE SHOULD BE ACTIVATED AS PER SCHEDULE
Monthly radigraphicc examinaton is carried out
Stabilize the device for 3 months
Donot remove device until radiographic outline is achieved
Class 2 elastics 4-6 Oz worn 24/ hrs /day during distraction and consolidation .this is done to
counteract softtissue forces at the time of bone healing
If not done reciprocal changes take place leading to detrimental artrhitic changes in condyle ,fossa,
disc . www.indiandentalacademy.com

DISTRACTION DEVICE SELECTION
D O devices have been developed for both external and Internal applications
Device should be selected based on mechanical capabilities and patient acceptance
DEVICE REQUIREMENTS
Any device should allow for
Transfer of distraction forces directly to the desired bone ends
Provide adequate rigidity until osseus consolidation occurs
TYPES OF DISTRACTORS –EXTAORAL DISTRACTORS
- INTRA ORAL DISTRACTORS
-SUBCUTANEOUS ,INTERNAL BURIED DEVICES(CRANIAL /MIDFACE
DISTRACTION)
EXTRA ORAL DISTRACTOR DEVICE
Mono directional appliance
Bidirectional appliance
Multi directional appliance
Drawbacks –Pin loosening , pin tract infection
External scars
Damage to tooth buds
Breakage of metal frame work
Damage to facial nerve
Non compliance

INTRA ORAL DEVICES
TYPES
-Bone borne
-Tooth Bone borne
-Tooth borne
ADVANTAGES
-No external scar
Good patient compliance
No Damage To Facial Nerve
Superior psychological tolerance
DRAWBACKS of INTRA ORAL
second surgery required for removal

FACTORS CONSIDERED FOR LENGTHENING OF MANDIBLE BY
INTRA/EXTRA ORAL APPLIANCES
-amount of desired lengthening and angular correction
-vector of distraction
-psychosocial requirements of the patients
LENGTHENING CAPABILITIES
Select appropriate length of device
The ratio between device activation and observed amount of distraction varies
sometimes as high as 2:1
Angular correction further decreases linear correction
DISTRACTION VECTOR PLANNING
Distraction vector defines the DESIRED DIRECTION of that the distal segment
has to move
factors to be considered
-osteotomy design ,location
masticatory muscle influence
occlusal interferences ,distraction device
adjustment

DISTRACTION DEVICE ORIENTATION
Place device parallel to the desired vector of distraction
-device oriented parallel to ramus – oblique distraction
-for vertical elongation of ramus –place device perp to maxillary occlusal plane
-for mandibular corpus lengthening place device parallel to maxillary occlusal plane
-oblique device orientation in ramus causes clockwise rotation of mandible
-INFLUENCE OF MASTICATORY MUSCLES
functional compensations are developed
check for any purposeful anterior positioning
compensate the masticatory forces with orthopedic forces
OCCLUSAL INTERFERENCES
POSTERIOR OCCLUSAL INTERFEENCES in mandibular lenghtening causes
clockwise rotation ,anterior openbite ,use of bite plane is necessary
DISTRACTION DEVICE ACTIVATION
angular device activation reduces the antero posterior lengthening of mandible
At least 10mm of lengthening should be done prior to angular correction
Orthopedic force may be instituted to produce angular correction
FUTURE GROWTH AND OVECORRECTION
IF GROWTH IS EXPECTED OVER CORRECTION IS PERFORMED
to reduce total number of surgeries
degree of over correction should provide a patient with a socially acceptable
appearance for the most years possiblewww.indiandentalacademy.com

ORTHODONTIC MANAGEMENT DURING DISTRACTION AND
CONSOLIDATION
distraction regenerate is a semi rigid structure that connects both the proximal
and distal segments of the mandible to each other this allows the orthodontist
to change the direction of the distal segments
HOFFMEISTER and co workers technique involves the removal of the
distraction device before the regenerate is consolidated and is there fore
malleable. the regenerate is then manipulated with orthodontic force to the
desired end treatment position and left to consolidate

DIRECTION OF DISTRACTION
simultaneous ramus and corpus lengthening
FORMULA –
Pin placement angle= 180- gonial angle x ramus deficiency
total defeciency
AMOUNT OF DISTRACTION
calculated by drawing a triangle ,two sides of which represent the amount of
mandibular corpus and ramus shortening
FORMULA –
Distraction amount =Dc +Dr -2(Dc Dr ) cos A
where Dc= corpus defeciency , Dr =ramus defecieny ,
A=gonial angle
OVERCORRECTION
calculated based on growth deficiency
the distribution of over correction must be the same as that for growth
defeciency for ex if distribution of growth deficiency between mandibular
ramus and corpus is 3:1 the ratio of over correction should be 3:1

CLASSIFICATION OF REGENERATE BONE
each regenerate is classified by
1)length of the forming regenerate from each host bone margin ,length of the
radiolucent inter zone relative to the length of distraction
2)the width of the forming regenerate relative to the width of the host bone
margin
3)the shape and density of forming regenerates and the radiolucent interzone
4)the presence or absence of corticalisation

Eleven types of mandibular regenerates are evident . Clinical stability is
dependent on radigraphic appearance of the regenerate ,not the duration of
consolidation period
-every regenerate with obliterated interzone and equal to the width of the host
bone margins was stable.
-regenerates with an un obliterated inter zone and those with obliterated
interzone but with unequal width to the host bone segments are questionable in
their stability.
30 -60.
/. Of bone minerals should be gained to be evident radiographically
corticalization is one of the last stages of regenerate consolidation and indicates
that distraction device can be removed and that bone can undergo functional
loading

Distraction begins after five days of latency at the rate of approximately
1mm/day
the elongation is completed in 3-4 weeks , device is left in place for 6-8 weeks
of consolidation until radiographic evidence of new cortical bone is seen
during distraction the distance between the pins and soft tissue –external
canthus to buccal commisure is measured weekly

OBSTRUCTIVE SLEEP APNOEA IN CHILDREN
candidates should be critically evaluated so that the risks and benefits of
distraction versus traditional treatment can be weighed
pre operative planning requires the use of sterolithographic model based on
C T scan of the infants
the fixation plates are cut pre surgically to fit the existing contours of the
model
due to fast healing response of infants the distraction is initiated
immediately after the surgery .Infant distraction proceeds at the rate of
1.5mm/day divided in three equal increments .This is followed by 3weeks
of consolidation
The introduction of lactosorb resorbable distraction devices have
brightened the areas of applications

MAXILLARY DISTRACTION
Midface deficiency manifests on the nasal and
paranasal regions as well as at occlusal levels
According to protocol photographs ,cephalograms
,dental models are obtained
leveling aligning of the arches is performed , the day
before the surgery a quad helix appliance is placed
In the surgical procedure dissection of the lateral
nasal process is done , an incomplete osteotomy is
performed above the roots of the canine and molar
tooth ,pterygo maxillary disjunction is not done
On the 5 th day distraction is initiated using a Petit
facial mask with force of 900 grams for total of 16-18
hours /day when the projected advancement is
obtained the amount of force is decreased to 450
grams per side and is maintained for two months
At 8-10 weeks post distraction there is radiographic
evidence of increase in size of tuberosity at the
pterygomaxillary junction
Gradual maxillary distraction by means of incomplete
osteotomies and external force systems is a minor
,relatively simple procedure with minimal morbidity

MIDFACE DISTRACTION

CRANIOFACIAL DISTRACTION

TRANSPORT D O
Transport D O is the technique of regenerating bone and soft tissue in a
discontinuity defect secondary to tumor or trauma.
An osteotomy is made 1.5 cms from the end of the distal stump of bone adjacent to
the discontinuity defect creating a transport disc . The transport disc is advanced
through the discontinuity defect by means of a distraction device.
New bone is created in the gap between the transport disc and original mandible
the leading edge of the transport disc becomes enveloped by a fibrocartilagenous
cap . If this cap is not removed prior to docking significant compressive forces
must be applied in order to cause necrosis of the fibrocartilage there by allowing
bony fusion
Transformational osteogenesis can be induced by compressive forces .This leads to
local necrosis of pathologic tissue followed by neovascularization of the fibrous
and cartilagenous tissue with local resorption at the bone ends leading to
progressive remodelling and fusion of the two segments .

MANDIBULAR SYMPHYSEAL WIDENING
Narrow mandible is often associated with narrow maxilla therefore it is
necessary to treat the maxillary transverse defeciency prior to mandibular
correction
The symphyseal distractor has an occlusal splint incrporated into the
design ,the surface is ground flat to avoid any occlusal interferances during
distraction
Mandibular growth remains unaffected after distraction , condylar
morphology remained un changed no posterior or lateral flatenning
occurred

ALVEOLAR RIDGE AUGMENTATION
Two Categories
VERTICAL AUGMENTATION-the transport alveolar segment is
translated vertically and the height of the ridge is increased
HORIZONTAL AUGMENTATION-transport alveolar segment is
translated horizontally thereby increasing the alveolar ridge width
distraction implants are suitable for increasing the height of the anterior
mandibular and maxillary alveolar ridge height alveolar ridgee height
should be started 1 week after surgery and performed slowly at the rate of
0.5mm per day.

INTRA ORAL CUSTOM DISTRACTION DEVICES

PERIODONTAL DISTRACTION

EFFECT OF DISTRACTION OSTOGENESIS ON TMJ
Although the distraction forces are applied locally the force of distraction could
be distributed to the adjacent tissues including condyle a secondary beneficial
effect appears to occur at the level of T M J. In an attempt to optimize the
potential effect of functional remodeling ,patients are encouraged to masticate
soft diet during entire distraction period .
Distraction has additional beneficial effect on the TMJ region .in unilateral
cases ,the affected side uprights in size and volume .the contralateral un
operated side shows no apparent deleterious changes at the level of TMJ. In
bilaterally affected and treated cases ,both condylar heads increase in size and
volume , becoming symmetric .

POTENTIAL MISTAKES
2 major groups
1)iatrogenic mistakes –primary or strategic mistake
- secondary or tactical mistakes
- technical mistakes
2)patient related mistakes -

POTENTIAL COMPLICATIONS
1)REGENERATE MALFORMATION
--HYPOTROPHIC REGENERATE
--HYPERTROPHIC REGENERATE
--REGENERATE FRACTURE
HYPOTROPHIC REGENERATE –delay
in bone tissue formation followed by an
alteration in regenerate structure
progresses to delayed consolidation
pseudoarthrosis occurs
Signs- lack of radiographic evidence of
distraction gap mineralization
Correction- decrease the rate of distraction
temporary cessation of
distraction
HYPERTROPHIC REGENERATE
excessive rate of bone formation
leads to premature consolidation
Signs –uniform tissue density throughout
the intersegmentary gap
Correction – if soft tissue permits 2-3mm of
acute distraction followed by gradual
distraction with increased rate

REGENERATE FRACTURE
USUALLY OCCURS AFTER FRAME REMOVAL ,or
progressively increasing soft tissue tension
,inadequate duration of consolidation period
treatment – Rx same as that for fractures
AXIAL DEVIATIONS
eliminate the main cause ,it may include replacement of the
device with a larger one ,reorientation of entire distraction vector
repositioning using elastic traction
SOFT TISSUE OVER STRETCHING
leads to degenerative necrotic changes that negatively affect the
outcome
BLOOD VESSELS
it is least resistant to compressive force , correction –releasing
the tension followed by reduced rate of distraction
PERIPHERALNERVES
D O complication includes 2-15/. Of nerve injury
occurs due to direct injury during osteotomy or indirectly by
focal nerve injury
by progressive edema or compression due to fixatures

In most cases lengthening by D O can be continued but at a slower rate
. Rehabilitation process may take more than a year
SKELETAL MUSCLES
Signs-limited range of motion , tenderness, joint contracture .
Complication – muscle atrophy
physical therapy with active or passive joint motion should be done
INFECTION
Mainly associated with external distraction devices management should be
started immediately antibiotics , releasing incisions should be given

CONCLUSION
AS We become more comfortable with the mere application of this exiting
technique ,we will most certainly find more novel uses for it ,as well as
different iterations of previous use
Future trends include –
refinements of distraction protocols
improvements in distraction devices
enhancements of regenerate using growth factors
modification of osteotomies
the uses and applications of D O in treating both simple and complex
deformities of craniofacial skeleton are restricted neither by mechanical
configuration of distraction device nor by the biologic capacity of the human
body but are actually only limited by the boundaries of our imagination .

REFERENCES :
1) The histology of distraction osteogenesis using different external fixators
;clinical orthop 241; 106; 1989
2)use of maxillary distraction osteogenesis for maxillary advancement ;J
Oral Maxillofac surg 1994 ;52 ;282-6
3)force levels and strain patterns during distraction osteogenesis . J Oral
Maxillofac Surg ;58 ;171-8 ;2000.
4) mandibular lengthening by gradual distraction ; AJODO 126 ;2004
5) T B OF CRANIOFACIAL DISTRACTION ; Cherakashin ,Cope ;
Samuchkov .
6) Experimental mandibular growth ; Plastic Re Constru Surg 1997 ;506

-Effect of mandibular distraction surgery on T M J ; AJODO 2001
-Simultaneous mandibular and maxillary distraction in hemifacial
microsomia in adults;Plast Reconstru Surg 1997 ;100 ;852 -61
-Distraction osteogenesis on irradiated mandible; Plastic Reconstru Surg
89;1-8 :1992.

Distraction osteogenesis (8)

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