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Oral Surgery > S2 -Facial deformity and orthognathic surgery > Flashcards

S2 -Facial deformity and orthognathic surgery Flashcards

1
Q

What is orthognathic surgery

A
  • surgery to treat facial disproportion i.e. correct dentofacial deformity jaw & facial bones
  • underdeveloped/overdeveloped/deformed
  • sub-specialty of OMFS
  • multi-disciplinary team: ortho, OMFS, dentistry, psychology accurate dx and tx planning is essential
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2
Q

Proportion of the face

A
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3
Q

Which type of radiograph is used for analyse/assess patient’s facial proportions

A

lat ceph

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4
Q

Lat ceph landmarks

A
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5
Q

What do different lines/planes/angles help us determine

A

facial proportions and where disproportion might be e.g. which jaw is at fault

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6
Q

Indications of orthognathic surgery

A
  • difficulty chewing or biting food
  • difficulty swallowing
  • TMD & headache
  • excessive occlusal wear
  • open bite
  • unbalanced facial appearance*
  • facial injury or congenital defects
  • receding chin
  • mandibular prognathism
  • incompetent lips
  • chronic mouth breathing & dry mouth
  • obstructive sleep apnoea

*mainly difficulty in accepting facial appearance, psychology needs to be assessed first

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7
Q

What characteristics are open bite usually associated with. How to correct orthognatically?

A

long face, posterior part of maxilla is too well developed

vertical maxillary excess is reduced by lifting mx up and auto-rotation of md back into different occlusion

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8
Q

Orthognathic tx for prognathic and retrognathic mandible

A

prognathic - push back md to rebalance face

retrognathic - bring md forward

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9
Q

Treatment goals of orthognathic surgery

A
  1. establish better function
  2. improve dental occlusion
  3. normalise/optimise facial aesthetics
  4. improve overall patient health
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10
Q

Surgical approaches for orthognathic surgery

A
  • Le Fort 1 maxillary osteotomy (to move maxilla)
  • Bilateral sagittal split osteotomy (splitting B/L ramus of md)
  • Bimaxillary surgery (balance movement in both jaws, most pts have both jaws moved)
  • Genioplasty (chin)
  • Segmental Osteotomies (mainly for chinese patients due to complexity of width and A-P discrepancy)
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11
Q

What has been done

A

le fort 1 maxillary osteotomy

bilateral sagittal split osteotomy

genioplasty

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12
Q

What are the fundamental surgical principles of orthognathic surgery

A

Osteotomy & Fixation

Osteotomy - to seperate mx/md from skull and/or TMJ articulation and then fix bone segment to new planned position

Fixation - achieved by Titanium miniplates and screws or IMF to allow stabilisation for bone healing

Pre-surgical orthodontics & Post-surgical orthodontics (very important)

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13
Q

How long does the process take?

A

Pre-surgical ortho - 1.5-2yr

Post-surgical ortho - 6m-1y

May require 3 years for combined orthodontic-orthognathic treatment

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14
Q

What is difficult about the pre-surgery ortho

A
  • teeth compensate for skeletal discrepancies to function so pt will have malocclusion
  • orthognathic surgery requires ortho to prepare teeth for surgical block movement into place, therefore during pre-surgery ortho → patient looks worse and exaggerates their malocclusion

(patient commitment of around 3 years + big surgical insult)

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15
Q

What is done during Le Fort 1 Osteotomy

A
  1. mx osteotomy sectioning lateral walls of mx sinus and lateral walls of nose
  2. sited ABOVE apices of maxillary teeth
  3. anteriorly: nasal septum divided from maxillary crest, posteriorly: mx seperated from pterygoid plates
  4. down-fracture & mobilisation
  5. maxilla repositioning - A/P, sup/inf, R/L (sometimes all) or
  6. maxilla segmentalisation - correction of width, occlusal plane, dento-alveolar relations
  7. titanium mini-plates used to hold in place, IMF to ensure mx will heal in the best plate
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16
Q

Why is it important to be careful with blood vessels during Le Fort 1 osteotomy

A

greater palatine vessels keep the palate alive

17
Q

What can a bilateral sagittal split osteotomy do? How is it done?

A
  • advance/set back md
  • correct rotations/adjust assymmetry
  • close small open-bite discrepancies
  1. There is a natural cleavage plane between B and L cortical plates
  2. sagittal split into: proximal (condylar) fragment, distal (dento-alveolar) fragment - reposition this fragment (not condylar as you will dislocate jaw)
18
Q

What is a genioplasty

A
  • can be solitary procedure or adjunct
  • advance or set back chin
  • augmented/reduced vertical dimension
  • rotated R or L - centre-line discrepancy
19
Q

Implication of orthognathic surgery in cleft lip & palate

A
  • cleft lip repair affects growth of maxilla and can have scarring
  • cleft lip at birth/ in childhood leads to restriction of mx growth
  • cleft palate may have lack of alveolar bone and delayed eruption and crowding

→ may have bone grafts etc in childhood, in young adulthood there may be need for complex orthognathic surgery to correct growth deformity primary in maxilla

19
Q

Implication of orthognathic surgery in cleft lip & palate

A
  • cleft lip repair affects growth of maxilla and can have scarring
  • cleft lip at birth/ in childhood leads to restriction of mx growth
  • cleft palate may have lack of alveolar bone and delayed eruption and crowding

→ may have bone grafts etc in childhood, in young adulthood there may be need for complex orthognathic surgery to correct growth deformity primary in maxilla

20
Q

Other craniofacial syndromes

A
21
Q

What is distraction osteogenesis

A
  • based on principle of encouraging new biological bone formation
  • corticotomy/osteotomy done and bony surfaces seperated by incremental traction when appliance is turned periodically in hopes of increasing new bone to fill the space
  • there is a simulataneous soft tissue lengthening
  • distraction can be I/O or E/O (for young children)
  1. latent period/early callus forms
  2. distraction phase started
  3. consolidation phase/ossification of callus

Oral Surgery (14 decks)

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