distraction osteogenesis in orthodontics

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!