DISTRACTION IN ORTHODONTICS IMPLICATIONS ROLE OF ORTHODONTIST IN MANAGEMENT OF SEVERE MAXILLOMANDIBULAR OR OROFACIAL DISCREPANCY SCOPE OF DISTRACTION OSTEOGENESIS

1. Distraction osteogenesis
Presenter : Dr.G V Shetty

2. • CONTENTS
 INTRODUCTION
 HISTORY OF D O
 BIOLOGICAL FOUNDATION .
 DISTRACTION DEVICE
CLASSIFICATION
 INDICATIONS AND CONTRAINDICATIONS
 ADVANTAGES AND DISADVANTAGES
 ORTHODONTIC CONSIDERATIONS
 FUTURE OF DISTRACTION OSTEOGENESIS
 CASES OF DO
 CONCLUSION
 REFERENCES

3. INTRODUCTION
 Facial asymmetry, mandibular hypoplasia, and congenital
malformation of jaws are common abnormalities of the craniofacial
complex.

4.  Traditionally, skeletal deformities have been corrected via functional
orthopedics in growing patients or orthognathic surgery with
skeleton fixation in non-growing patients

5.  Many congenial deformities require large amount of skeletal
movements which is perhaps not possible with orthognathic
surgery may lead to compromise in function and esthetics.

6. INTRODUCTION
DISTRACTION OSTEOGENESIS (Transosseous synthesis)
(Osteodistraction)
• DEFINITION: Is a biological process of new bone
formation between the vascularised margins of
bone segments when they are gradually seperated
by incremental traction - COPE (1999)

8. History
Earlier attempts at D.O. of long bones by Alessandro Codivilla
(1905)

9. History
First mandibular osteodistaction by Wassmund&Rosenthal
(1927) (intraoral tooth borne appliance)

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

11. • In 1948 ,crawford followed gradual
incremental traction to the callus of mandible
• In 1957 traucher and obwegesser introduced
the concept of sagittal split osteotomy .

12. • HISTORICAL PERSPECTIVE
 Mc’Carthy– (1989) conducted the first reported human
trial of craniofacial distraction using external fixators.
 4 children with craniofacial anomalies were
subjected to a distraction protocol of upto three weeks
followed by a 8-10 week consolidation.
 Long-term studies of the same patients indicate a
successful result.

13. McCarthy (1992)
• – DO to lengthen congenitally hypoplastic
mandible

14. Rachmiel et al (1993) and Blocks et al (1995)
– Maxillary distraction
• Polley et al (1995)
– Midface distraction with externally fixed cranial halo frame

15. 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.

16. DISTRACTION OSTEOGENESIS
A BIRD EYE-VIEW THE ORIGINS AND EVOLUTION OF
DO IN THE CRANIOFACIAL REGION
 Progression from extra-oral to intraoral devices
 Progression from manual devices to motorized
devices
 Progression from the removable fixators to
biodegradable fixators

17. • PHASES OF DISTRACTION OSTEOGENESIS
• Steps involved :
a) Corticotomy/Osteotomy
b) Latency period
c) Distraction phase
d) Consolidation phase
e) Remodelling

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

20. 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

21. 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

22. 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

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

24. HISTOLOGY OF DISTRACTION OSETOGENESIS
LATENCY PERIOD DISTRACTION PHASE

25. Latency
Histological sequence in latency period in distraction
osteogenesis is similar to that of fracture bone healing
and in this phase soft callus formation takes place. Initial
latency period is recommended is between 5 to 10 days.

26. Distraction
In this phase normal process of fracture healing interrupted by the
application of gradual traction to the soft callus.
As a result of the tension created by this traction force a dynamic
microenvironment created which encourages new tissue formation in the
direction parallel to the vector
of traction.
During distraction, four zones[4] appear: a fibrous, less vascular center with
collagen fibers parallel to the distraction vector, a transition zone of early
bone formation, a bone remodeling zone, and mature bone at
the ends. Distraction process is generally carried out at
the rate of 0.5 to 1 mm per day.

27. CONSOLIDATION REMODELLING

28. Consolidation and remodeling
Bone maturation occurs and continues over a period of
a year or more before the structure of the newly formed
bony tissue is comparable to that of preexisting bone
and in which soft tissue adaptation also occurs. After
distraction ceases, this soft callus ossifies and a distinct
zone of woven bone completely bridge the gap mainly
by intramembranous ossification.

29. • Indications of Maxillo Mandibular Distraction
Osteogenesis
1. Severe mandibular retrognathia/micrognathia
2. Craniofacial syndromes: hemifacial microsomia, Treacher Collins syndrome,
Nager syndrome, Pierre Robin sequence
3. Severe mandibular asymmetry
4. Post-traumatic deficient mandibular growth and temporomandibular joint
ankylosis
5. Revision mandibular orthognathic surgery
6. Mandibular retrognathia with temporomandibular joint disease or juvenile
rheumatoid arthritis
7. Mandibular retrognathia with obstructive sleep apnea
8. Mandibular defects from tumor resection
9.Midfacial hypoplasia .
10.Expansion of mandibular symphysis

30. Indications of D O

34. 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 Unidirectional Distractors

35. 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

36. 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

37. 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

38. • Advantages of Distraction Osteogensis
1. Allows greater mandibular lengthening of 10–30 mm
2. Can be applied to unusual bony and soft tissue anatomy
3. Allows slow gradual soft tissue adaptation to extreme mandibular
lengthening
4. Minimal to no skeletal relapse after extreme mandibular lengthening
5. Can be applied to neonates, infants, and pediatric patients with obstructive
sleep apnea
6. Less invasive surgery compared with bone-grafting procedures
7. Avoids intermaxillary fixation
8. Avoids bone grafting and potential donor-site morbidity
9. Can be used for mandibular widening
10. Fewer adverse temporomandibular joint effects in response to
asymmetric lengthening
11. Decreased hospitalization time and cost compared with bone grafting
12. Less need for blood transfusion

39. • Drawbacks of Distraction Osteogenesis
1. Skin scars
2. Technique sensitive surgery, equipment sensitive surgery
3. Possible need for second surgery to remove distraction device and patient
compliance
4. Transient changes in temporomandibular joint
5. An adequate bone stock is necessary to accept the distraction appliances
and to provide suitable
6. opposing surface capable of generating a healing callus
7. Damage to tooth germ
8. Premature consolidation
9. Damage to inferior alveolar nerve
10. Bilateral Coronoid Ankylosis
11. Tendency towards clockwise rotation

40. Classifications of distraction osteogenesis
techniques

42. Orthodontics considerations
DIAGNOSIS
• 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

44. 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

45. Factors affecting DO

46. ORTHODONTIC TREATMENT PROTOCOL
• PRE DISTRACTION ORTHODONTICS
• ORTHODONTICS DURING DISTRACTION AND
CONSOLIDATION PHASE
• POST DISTRACTION PHASE
• RETENTION.

47. • The Orthodontist’s role
a. Decompensation of the dentition
b. Planning the distraction vector
c. Bone Moulding using intermaxillary elastics
d. Post-distraction Orthodontics

48. DISTRACTION OSTEOGENESIS
PLANNING THE DISTRACTION VECTOR
VERTICAL HORIZONTAL OBLIQUE

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

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

51. Transverse plane (Model I)
– Distractors oriented parallel to the lateral surface of
mandible

52. Transverse plane (Model II)
– Distractors oriented parallel to each other and to
midsagittal axis

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

54. • • Sagittal plane (Model V)
• Sagittal plane (Model VI)

55. 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

56. MANIBULAR
DISTRACTION
OSTEOGENESIS

58. MAXILLARY
DISTRACTION

60. For V shape mandible
• Severe mandibular crowding
• Brodie’s syndrome
• To avoid inderdental stripping or
extractions
Symphyseal Distraction

61. Symphyseal Distraction

62. DENTAL DISTRACTION

63. DISTRACTION OSTEOGENESIS
CURRENT SCOPE OF DO
 Correction of Maxillo-Mandibular deformities
a) Maxillary lengthening
b) Mandibular lengthening
c) Maxillary and Mandibular widening
d) Lengthening of the Hard palate
e) Distraction in other cranio-facial areas.

64. DISTRACTION OSTEOGENESIS
CURRENT SCOPE OF DO
 Alveolar ridge augmentation
 Transport disc and Transformation
osteogenesis.
 Dental Distraction.

65. DISTRACTION OSTEOGENESIS
Directions for the future
a. Refinements in the distraction protocol
b. Improvement in distraction devices
c. Enhancement of regenerate maturation

66. Conclusion
• Distraction osteogenesis has revolutionised the management
of maxillomandibular deformities .
• Patients with severe deformities can be better managed by
distraction osteogenesis at much lower risk and complications
than with orthognathic surgery
• Distraction osteogenesis has indeed redefined the envelope
of discrepancy .