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Distraction Osteogenesis
Dr. Waqar JeelaniResident - Orthodontics
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Distraction Osteogenesis
“A biological process of new bone formation between the surfaces of osteotomized bone segments that are separated gradually by incremental traction”Distraction Histogenesis :– Adaptive regenerative changes in surrounding
soft tissues
Historical Overview
Alessandro Codiwilla (1905)– First report of surgical limb lengthening– Oblique osteotomy and external traction pins– Complications: infections, overstretching, poor
blood supply, and inadequate fixation
Historical Overview
G.A. Ilizarov (1950’s)– Lengthening limbs through gradual distraction
of fracture callus– Rhythm and rate of distraction– Minimal complications
Historical Overview
McCarthy (1992)– DO to lengthen congenitally hypoplastic
mandible
Historical Overview
• Rachmiel et al (1993) and Blocks et al (1995)– Maxillary distraction
• Polley et al (1995) – Midface distraction with externally fixed cranial
halo frame
Historical Overview
Chin and Toth (1996)• Mandibular alveolar distraction osteogenesis to
increase the height of the alveolus
Chin M, Toth BA. Distraction osteogenesis in maxillofacial surgery using internal devices: review of five cases. J Oral Maxillofac Surg. 1996 Jan;54(1):45-53.
Distraction Techniques
Physeal Distraction• Distraction of growth
plate• Endochondral bones
Callotasis• Distraction of
healing callus• Membranous bones
Types of Distraction Osteogenesis
• Defined on the number of foci at which osteogenesis occurs:– Monofocal elongation DO – Bifocal distraction– Trifocal distraction
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Biology of Distraction
1. Osteotomy/Corticotomy phase2. Latency phase3. Distraction phase4. Consolidation phase5. Remodeling phase
Osteotomy Phase• Divides the bone into two segments• Triggers process of bone repair– Angiogenesis– Fibrogenesis– Osteogenesis
Latency Phase
• Period from bone division to onset of distraction• Inflammation and soft callus formation of the
fractured bone• Soft callus formation begins 3-7 days and lasts 2-3
weeks• Latency period = 5-7 days
Distraction Phase
• Characterized by the application of traction forces to osteotomized segments
• Rate : 1 mm/day
• Rhythm : 0.25 mm every 6 hours
0.5 mm twice a day
• Duration : 1-3 weeks
Consolidation Phase
Cessation of traction forces to removal of distractor
• Newly formed bone mineralizes and increases in bone density and strength
Duration: 3- 4 months
Remodeling Phase
• Removal of distractor to application of functional loading
• Formation of lamellar bone
Indications
• Congenital retrognathic syndromes • Severe mandibular deficiency > 10-15 mm• A short mandibular ramus • TMJ degenerative disease• Obstructive sleep apnea• A narrow, V-shape mandible• Maxillary deficiency in CLP or
Craniosynostosis• Post-traumatic growth disturbance• Atrophy of edentulous segments• Oncologic mandibular osseous defects
Advantages
• Safe and effective surgical technique can be performed on outpatient basis
• Can be done in children as young as 2 years • Distraction histogensis results in growth of
associated functional matrix • Long term improvement in condylar
morphology• Greater degree of correction can be achieved• Grafts are not required• Minimal skeletal relapse
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Disdvantages
• Requires second surgery to remove distractor appliances
• Risk of infection at surgical site is greater• Pain and discomfort during distraction• Required meticulous planning• Results are not as precise as orthognathic
surgery
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Treatment Planning
• Extraoral Examination– Forehead, orbit, zygoma, external ear– Oral commissure, chin, mandibular angles
• Intraoral Examination– Occlusion– Occlusal plane
• Function– Maximum interincisal opening– Mandibular deviation or deflection– TMJ evaluation– Sensory nerve function
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Treatment Planning
• Diagnostic Records– Standard extraoral and intraoral photographs– Dental models articulated on a semi-adjustable
articulator– Lateral and PA cephalograms– OPG– CBCT – CT Scan– Stereolithographic models
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Factors Affecting DOLocal Factors Systemic Factors Distraction Factors
Osteoprogenitor Supply Age Rate of Distraction
Blood Supply Metabolic Disorders Frequency of Distraction
Infection Vitamin D Deficiency Latency Period
Soft Tissue Scarring Connective Tissue Disease
Rigidity of Fixation
Bone Stock Steroid Therapy Consolidation Period
Prior Radiation Therapy Calcium Deficiency Length of Regenerate
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Imola MJ, Ducic Y, Adelson RT. The secondary correction of posttraumatic craniofacial deformities. Otolaryngol Head Neck Surg. 2008;39(5):654-60.
Treatment Planning
• Distraction Device Orientation
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Biomechanical Considerations
• Factors related to distractor device
• Factors related to bone and surrounding tissues
• Factors related to device orientation
Properties of Distractor
• Mechanical integrity of device• Number, length and diameter of fixation pins• Material properties
Quality of Hard and Soft Tissues
• Shape of the bone• Cross-sectional area• Density of bone• Tension of soft tissues• Site of osteotomy and joint function
Distractor Orientation
• Transverse plane (Model I)– Distractors oriented parallel to the lateral
surface of mandible
Distractor Orientation
• Transverse plane (Model II)– Distractors oriented parallel to each other
and to midsagittal axis
Distractor Orientation
• Transverse plane (Model III & IV)– Distractors placed parallel to lateral surface of
mandible (III), parallel to each other (IV)
Distractor Orientation• Sagittal plane (Model V)
• Sagittal plane (Model VI)
Craniofacial DistractorsC
rani
ofac
ial D
istr
acto
rs External Distractors
Unidirectional
Bidirectional
Multiplanar
Internal Distractors
Tooth-Borne Distractors
Bone-Borne Distractors
Hybrid Distractors
External Unidirectional Distractors
• Single calibrated rod with two clamps• Each clamp holds two 2-mm half-pins• 20-24mm of bone posterior to last tooth bud
• Limitations: – Difficulty in predicting direction – Inability to change direction– Scarring
External Bidirectional Distractors
Molina and Ortiz Monasterio• Two geared arms 5 cm in length• Middle screw - change angulation• Double osteotomy (horizontal in ramus and vertical in
corpus)• Two 2-mm pins in each segment of bone
External Bidirectional Distractors
Advantages:– Additional degree of freedom– Deficiencies in more than one plane– Two osteotomies - flexible distraction – Easy and optimal device placement
Potential problems– Risk for avascular necrosis of intervening
segment – Damage to tooth buds during pin placement
External Multiplanar Distractors
• Two distraction rods with sliding clamps connected in by multiplanar hinge in the middle
• Two arms extend with pin clamps at either end
• Each quarter turn results in 0.25 mm of expansion
Use of Intermaxillary Elastics
• Modification of distraction vectors• Intermaxillary elastics can have skeletal
effects during distraction– Secondary to molding of the regenerate
• “Fine tuning” of the occlusal outcome• Elastics may be worn in Class II, III, vertical,
or transverse pattern• Helpful in the retention of results
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Mandibular Extra-oral Distraction Devices
Advantages• Small children
applicability• Simplicity of
attachment• Ease of manipulation• Multiplanar adjustment• Low infection rate• Out patient surgery
Disadvantages• Apprehension• Bulky appliance• Social inconvenience• Facial scars• Reduced consolidation
period
Internal Distractors
AdvantagesEliminate the problems of:– Facial scarring– Pin tract infections
• Better esthetics• Long consolidation
period possible
Disadvantages– Unidirectional
distraction– Difficult activation of
ramus distractors– Poor fit– Trauma to
surrounding tissues
Internal Tooth-Borne Distractor Device
• Preformed stainless steel crowns • Distractor fabricated on cast, crowns
cemented• An osteotomy made between selected teeth,
distractor placed • Latency period: 3-4 days• Consolidation period 5 weeks
Symphesial Distraction
• For V shape mandible• Severe mandibular crowding• Brodie’s syndrome• To avoid inderdental stripping or extractions
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Symphesial Distraction
• Osteotomy Cuts
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Symphesial Distraction
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Symphesial Distraction
Samchukov et al. (1998) reported 0.34-degree condylar rotation for every 1 mm of widening
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Samchukov, M.L., Cope, J.B. Cherkashin A.M., (2001) The biomechanical effects of distraction device orientation during mandibular lengthening and widening. In: Samchukov, M.L., Cope, J.B., Cherkashin, A.M. (Eds.), Craniofacial distraction Osteogenesis. Mosby, St. Louis, pp. 131–146.
Periodontal Bone Regeneration
• Faber J, Azevedo RB, Báo SN. Distraction osteogenesis may promote periodontal bone regeneration. J Dent Res. 2005 Aug;84(8):757-61. 43
Distraction Osteogensis for Vertical Bone Augmentation
• McAllister BS, Gaffaney TE. Distraction osteogenesis for vertical bone augmentation prior to oral implant reconstruction. Periodontol. 2003;33:54-66.
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Thank you!