Orthognathic Surgery and Facial Asymmetry

1. Orthognathic Surgery
DR. HADI MUNIB
ORAL AND MAXILLOFACIAL SURGERY RESIDENT

2. Outline
• Craniofacial growth
• Diagnosis and Treatment Planning
• Mandibular Orthognathic Surgery
• Maxillary Orthognathic Surgery
• Facial Asymmetry
• References

3. Craniofacial Growth

4. Craniofacial Growth

5. Craniofacial Growth

6. Craniofacial Growth

7. Craniofacial Growth

8. Craniofacial Growth

9. Diagnosis and Treatment Planning
• Identification of pathology and causes
• Patients with severe discrepancies in the size and position of their
jaws and their teeth often have difficulty in oral function.
• Chewing, Speaking, TMJ?
• Dentist – Patient Communication
• Expectations

10. Aetiology
• Genetic pattern
• Embryonic disturbance of growth`
• Postnatal damage before or after growth has ceased
• Abnormal regulation of growth after birth
• Other aetiology

11. Indications
• Severe class III
• Severe class II
• Severe anterior open bite
• Markedly increased overbite
• Skeletal asymmetry

12. Classification
• Symmetrical Anomalies
• Asymmetrical Anomalies

13. Data Collection
• Clinical examination and is supplemented with static and dynamic recordings
of the patient in three spatial dimensions.
• Most commonly used method photography, study models, and cephalometric
radiographs.

14. Treatment Planning
• Full detailed history
• Communication and psychological
• Extra and intraoral examination
• Facial aesthetics
• Radiography
• Study models
• Photographs
• Team planning

16. Clinical Examination
• Inter-Pupillary Distance = 65 +/- 3
• Inter-Canthal Distance = 32 +/- 3
• Inter-Canthal Distance = Alar Base = Palpebral Fissure
• Upper Lip = 20 – 22 mm
• Amount of incisor show at rest: 2 mm
• Amount of incisor show smiling: 100%
• Crown Height: 9 – 12 mm
• Gingival Display on smile: < 2 mm

22. Radiography
• Lateral Cephalometric and Panoramic Radiographs are important
tools for Assessment and as an adjunctive in diagnosis and
treatment planning.
• In specific Cases, it’s better to have CBCT for definitive treatment
planning and treatment.

24. Model Surgery

25. Pre-Surgical Orthodontics
• The orthodontist is responsible for positioning the teeth to the
most desirable position over basal bone in preparation for surgery.
• De-Compensation
• Worsening the case as much as possible

26. Surgical Planning
• Avoid incisions on the face
• First the bone then the soft tissue
• First correct the profile then the occlusion
• Occlusion as important as profile
• Eliminate the excessive growth as early as possible
• Planning methods
• Rigid fixation

27. Mandibular Orthognathic Surgery
• BSSO
• VSSO
• Inverted L,C Osteotomy
• Genioplasty
• Body Osteotomies

28. Mandibular Orthognathic Surgeries
• Anatomic Considerations
• Vascular Supply
• Nervous Supply
• Muscles [Length – Direction of function]

29. Bilateral Sagittal Split Osteotomy BSSO
• Predominant Orthognathic Surgery in the mandible
• Intra-Oral Approach
• Every Possible move that includes the entire horizontal ramus of the mandible
• Advancement, Setback and Rotation
• The incision is started on the anterior portion of the vertical ramus.
• Upper limit is 6 mm
• Rigid Fixation

30. Technique BSSO

31. Technique BSSO

32. Complications - BSSO
• Stability; the amount of advancement and the amount of relapse
• Nerve Damage; 19% reported lingual nerve sensory changes of
whom 69% reported a resolution of symptoms within a year and
88% reported altered daily activities.
• TMJ Dysfunction
• Bad Split

35. Vertical Subcondylar Osteotomy
• Different Names
• Extra-oral Approach
• Setback or Rotation
• Technique

36. Intraoral VSO
• The incision is made from midway up the anterior border of the ramus to the
first molar.
• Exposure of the entire ramus.
• Osteotomy; The cut should be made no more than 5 to 7 mm anterior to the
posterior border at the anticipated level of the foramen
• Forward and lateral movement of the proximal fragment by a small gauze pack
while the opposite side is being completed.
• The mandibular dentition is brought into its new position.
• MMF

37. Technique

38. Extraoral VSO
• Approximately 4 cm incision made 2 cm below the angle and the
inferior border of the mandible.
• Inferior Border of the mandible
• MARGINAL MANDIBULAR NERVE
• The external approach has been advocated for large mandibular
setbacks of greater than 10 mm, difficult asymmetries, or large
vertical moves in patients with unusual facial structure.

39. Technique

40. Complications
• Stability
• Neural Damage; The incidence of trauma to the inferior alveolar
nerve at the time of surgery varies from “rare” to 36%.
• TMJ Dysfunction

41. Inverted L and C Osteotomy
• Both the condyle and coronoid in the same segment.
• The two procedures that seem to be the most popular are the inverted L
and the C osteotomies.
• Extra- Oral Approach
• Inverted C; Horizontal mandibular Deficiencies, some AOB cases
• Inverted L; correction of most kinds of mandibular horizontal
discrepancies, including anterior open bite.
• Generally advancements of the distal segment with either technique
require bone grafting to ensure adequate bone union.

42. Inverted L and C Osteotomy
• C Osteotomy; inferior horizontal cut.
• The submandibular incision is made 2 cm below the angle and inferior
border of the mandible, approximately 6 cm in length.
• The medial periosteum may have to be elevated from some of the distal
fragment to allow its advancement.
• Moist gauze is placed in the wound.
• Other side Osteotomy
• Mandibular teeth into the new occlusal position and secured with
maxillomandibular dental fixation.

43. Technique

45. C Osteotomy
• Horizontal cut that extended forward from the vertical cut below
the inferior alveolar canal.
• This permitted a larger amount of bone contact when the
mandible was advanced.
• They also realized the problems caused by advancing the coronoid
process and recommended either cutting the coronoid loose
(coronoidotomy) or including it with the proximal segment (C
osteotomy).

46. C Osteotomy

47. Complications
• Stability
• Nervous injury
• Scar

48. Genioplasty
• Intraoral Incision
• Horizontal Osteotomy
• Mental Nerve
• Apices of teeth

50. Le Fort 1 Osteotomy
• Versatile; Advancement, Setback.
• Upper limit; 6 mm, 3 mm.
• Impaction; Open bite, Vertical Maxillary Excess.

51. Le Fort 1 Osteotomy

56. Facial Asymmetry

57. Facial Asymmetry
• Facial symmetry has a high correlation with attractiveness.
• Greater degrees of asymmetry are correlated with clinical depression,
neurosis, inferiority complex, poor self-esteem and general poor quality of
life.
• Congenital Anomalies; acquired during in utero development and can be
subdivided into malformations (developmental), deformities (Position or
form), and disruptions (disruption of a process).
• Acquired anomalies are conditions arising from either trauma or pathology.

58. Hemifacial Microsomia
• Craniofacial malformation of the first and second branchial arches presenting
with asymmetric unilateral or bilateral hypoplasia of the orbit(s), maxilla,
mandible, ear, cranial nerves and soft tissue.
• Proliferation and migration of embryonic neural crest cells/ hemorrhage of the
stapedial artery during fetal development.
• The true etiologic factors still remain unknown.
• Two important factors need to be considered in the treatment planning of HFM:
• Facial growth potential and/or restriction and its effect on surrounding
structures
• Degree of hypoplasia involving the glenoid fossa, mandibular condyle, and ramus
unit.

59. Hemifacial Microsomia
• HFM is the most frequently encountered form of isolated facial asymmetry and
the second most common congenital facial anomaly after cleft lip and palate
• Incidence between 1 : 5000 and 1 : 5600 live births.
• Males appear to be more frequently affected than females (3 : 2)
• The right side is affected more often than the left side.
• It is usually unilateral (70%) and always asymmetrical if it exhibits bilaterally
• Although “hemifacial” refers to one half of the face, the condition is bilateral
in 10-31% of cases, with one side being more affected than the other.
• In 48% of cases, the condition is part of a larger syndrome such as Goldenhar
syndrome

60. O.M.E.N.S Classification
• O: Orbit
• M: Mandible
• E: Ear
• N: Nerve
• S: Soft Tissue

61. Pruzansky and Kaban Classification
• Presence or absence of critical structures.
• HFM type I deformity; a generalized mild hypoplastic state, mild mandibular
retrognathia and facial asymmetry.
• HFM Type IIA; a hypoplastic cone-shaped condylar head.
• HFM Type IIB; Moderate to severe hypoplasia, TMJ function is unsatisfactory
• HFM Type III; Complete absence of the mandibular ramus and condyle.

64. Treatment
• An early approach:
• A costo-chondral bone graft
• Distraction osteogenesis.
• A late approach
• A classical osteotomy (i.e. bimax surgery with canting the maxilla in
combination with advancement of the mandible and lengthening the ramus)
• A bimaxillary distraction osteogenesis

65. Hemimandibular Hyperplasia/Elongation
• Diffuse enlargement of the condyle, the condylar neck, and the mandibular
ramus and body.
• No etiologic factor has been established.
• Condylar growth patterns can be evaluated by serial clinical comparisons,
cephalometric tracings, and bone scanning with technetium 99m
phosphate.
• Treatment modalities have ranged from condylectomy to orthopedic
maxillary management.

66. Hemimandibular Hyperplasia/Elongation
• Obwegeser and Makek classified CH associated facial asymmetries into three
categories:
1. Hemimandibular hyperplasia which causes asymmetry in the vertical
plane
2. Hemimandibular elongation which causes asymmetry in the transversal
plane,
3. A combination of the previous two entities.

69. Diagnosis
• OPG
• Models
• Photos
• Radioisotope Bone Scan
• CT

71. Treatment
• Consider evidence of neoplasia
• Consider evidence of continued growth
 Growth has not ceased:
 Condylar shaving or condylectomy followed by correction of
deformity
Growth has ceased:
 Orthognathic surgery
 Surgical camouflage

73. Distraction Osteogenesis
• Generates bone and soft tissue
• Craniofacial reconstruction, including orthognathic surgery, cleft lip and palate
reconstruction
• Osteotomy of the bone site with minimal periosteal stripping
• Latency period: 3, 5, or 7 days, depending on the surgical site
• Distraction rate: 1.0 mm per day (0.5–2.0 mm)
• Distraction rhythm: continuous force application is best, yet device activation
bid is more practical and allows for better patient compliance
• Consolidation: until a cortical outline can be seen radiographically across the
distraction gap, usually 6 weeks

74. Distraction Osteogenesis
• Large Skeletal Movements.
• Soft tissue and nerves
• Matrix ossification

75. Distraction Osteogenesis
• Osteotomy in an area adjacent to an area of bone deficiency.
• Applying slow tension forces separates the bony edges
• Regenerate chamber from which the new bone and soft tissues are formed.
• Rate of Distraction
• Rhythm of Distraction
• Regenerate Bone

76. Distraction Osteogenesis
• Osteotomy/ Surgical Phase; Surgery and Distractor placement
• Latency Phase; Inactivated, Early bone formation lasts 7 days
• Distraction Phase; 1 mm/ day, activation twice daily
• Consolidation Phase; Appliance remains, regenerate bone is mineralized
• Remodeling Phase; Appliance is removed, normal functional loads until
complete maturation

77. Advantages
• Application of high forces
• Decreased Neurosensory loss
• Less TMJ Damage
• Better Long-term Stability

78. Disadvantages
• Technique sensitivity and sometimes results in less than ideal occlusal
positioning, resulting in discrepancies such as small open bites or
asymmetries.
• Two Procedures; Application and removal of appliance
• Increased Cost and Long treatment period

81. Surgical – Assisted Rapid Palatal Expansion
• An adult maxilla with significant transverse deficiency is nearly
impossible to correct with conventional orthodontic treatment.
• In these cases, the expansion device is secured in place by the
orthodontist. A surgical procedure is then completed by performing the
bone cuts as described for a Le Fort I osteotomy, with the exception
that the most posterior attachment of the lateral nasal wall and
perpendicular plate of the palatine bone are not divided. A midline cut
is also completed to create separation between the central incisors
extending along the midpalatal suture. After a latency period the
expansion device is activated 1 mm per day until the desired expansion
takes place .

82. Surgical- Assisted Rapid Palatal Expansion
• During this time, a space develops between the central incisors, along the
midpalatal suture, and at the area of the osteotomy along the lateral
maxillary wall.
• The regenerate bone gradually fills and matures in these areas.
• The appliance is then removed, and active orthodontic treatment is begun to
close the spaces between teeth, properly align the arch, and maintain the
expansion

83. Surgical- Assisted Rapid Palatal Expansion
• In the case of mandibular deficiency, the initial surgical procedure involves
performing an osteotomy and placement of the distraction appliance. After a
latency period of 7 days, the distraction occurs with a rate and rhythm of 1
mm per day (completed by activating the appliance 0.5 mm twice each day).
• Once this distraction is complete, the appliance is left in place for the
consolidation phase, which is usually 2 or 3 times the amount of time required
for the distraction phase. The appliance is then removed, and active
orthodontic treatment continues

84. Surgical- Assisted Rapid Palatal Expansion
• Distraction appliances are also available for maxillary and midface
advancement.
• In patients with a cleft lip and palate, substantial scarring often occurs from
multiple previous surgical procedures. This scarring combined with significant
growth abnormalities creates soft tissue limitations that may prevent single-
stage correction with conventional orthognathic surgical techniques. DO can
be effective in treatment of these patients by gradually stretching the soft
tissue envelope, generating new soft and hard tissue, eliminating the need for
graft harvest, and providing satisfactory long-term stability.

85. References
• Chapter 53: Craniofacial Growth
• Chapter 54: Treatment Planning
• Chapter 56: Principles of Mandibular Orthognathic Surgery
• Chapter 57: Principles of Maxillary Orthognathic Surgery
• Chapter 58: Management of Facial Asymmetry.
• Chapter 62: Distraction Osteogenesis

87. THANK YOU