Distraction Osteogenesis in Orthodontics

A small but comprehensive description of distraction osteogenesis in orthodontics.

1. Distraction Osteogenesis Dr. Waqar Jeelani Resident - Orthodontics 1

2. Distraction Osteogenesis “A biological process of new bone formation between the surfaces of osteotomized bone segments that are separated gradually by incremental traction” Distraction H istogenesis : Adaptive regenerative changes in surrounding soft tissues

3. 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

4. Historical Overview G.A. Ilizarov ( 1950’s) Lengthening limbs through gradual distraction of fracture callus Rhythm and rate of distraction Minimal complications

5. Historical Overview McCarthy ( 1992) DO to lengthen congenitally hypoplastic mandible

6. 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

7. 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 .

8. Distraction Techniques

9. Types of Distraction Osteogenesis Defined on the number of foci at which osteogenesis occurs: Monofocal elongation DO Bifocal distraction Trifocal distraction 9

10. Biology of Distraction Osteotomy/ C orticotomy phase Latency phase Distraction phase Consolidation phase Remodeling phase

11. Osteotomy Phase Divides the bone into two segments Triggers process of bone repair Angiogenesis Fibrogenesis Osteogenesis

12. 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

13. 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

14. 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

15. Remodeling Phase Removal of distractor to application of functional loading Formation of lamellar bone

16. 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

17. 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 17

18. 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 18

19. 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 19

20. 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 20

21. Factors Affecting DO Local 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 21 Imola MJ, Ducic Y, Adelson RT. The secondary correction of posttraumatic craniofacial deformities. Otolaryngol Head Neck Surg. 2008;39(5):654-60.

22. Treatment Planning Distraction Device Orientation 22

23. Biomechanical Considerations Factors related to distractor device Factors related to bone and surrounding tissues Factors related to device orientation

24. Properties of Distractor Mechanical integrity of device Number, length and diameter of fixation pins Material properties

25. 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

26. Distractor Orientation Transverse plane (Model I) Distractors oriented parallel to the lateral surface of mandible

27. Distractor Orientation Transverse plane (Model II) Distractors oriented parallel to each other and to midsagittal axis

28. Distractor Orientation Transverse plane (Model III & IV) Distractors placed parallel to lateral surface of mandible (III), parallel to each other (IV)

29. Distractor Orientation Sagittal plane (Model V) Sagittal plane (Model VI)

30. Craniofacial Distractors

31. 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

32. 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

33. 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

34. 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

35. 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 35

36. Mandibular Extra-oral Distraction Devices Advantages S mall children applicability S implicity of attachment E ase of manipulation M ultiplanar adjustment L ow infection rate Out patient surgery Disadvantages Apprehension Bulky appliance Social inconvenience Facial scars Reduced consolidation period

37. Internal Distractors Advantages Eliminate 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

38. 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

39. Symphesial Distraction For V shape mandible Severe mandibular crowding Brodie’s syndrome To avoid inderdental stripping or extractions 39

40. Symphesial Distraction Osteotomy Cuts 40

41. Symphesial Distraction 41

42. Symphesial Distraction Samchukov et al. (1998) reported 0.34-degree condylar rotation for every 1 mm of widening 42 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.

43. 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

44. 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 . 44

45. Thank you!