Orthognathic and Facial Esthetic Surgery
This domain tests cephalometric planning, surgical sequencing, stability and patient selection.
Core rules
- Assess skeletal, dental and soft-tissue relationships. Cephalometrics include SNA, SNB, ANB, occlusal plane and incisor inclination. Use model surgery or virtual surgical planning.
- Le Fort I surgery moves the maxilla; bilateral sagittal split osteotomy moves the mandible; genioplasty changes the chin. The maxilla is often treated first to establish the occlusal plane.
- Stability varies: maxillary impaction is relatively stable; large mandibular advancement has relapse risk and may need grafting.
- Screen for obstructive sleep apnea and TMJ disorders. Condylar resorption can affect planning.
- Esthetic assessment includes facial proportions, smile line and nasal change after maxillary surgery.
Worked example
A patient with Class III malocclusion has maxillary hypoplasia. Plan Le Fort I advancement and possible BSSO setback; check incisor decompensation, airway and speech. Do not camouflage a large skeletal discrepancy with dental extraction alone.
Traps
Planning from a cephalogram alone; ignoring TMJ status; not warning about numbness; overadvancing the mandible in obstructive sleep apnea.