Orthognathic Surgery and Dentofacial Orthopedics
What the exam tests
Indications, presurgical orthodontics, surgical options, stability, and the teamwork required for combined cases.
Core rules
- Indications: discrepancies beyond orthodontic camouflage, severe asymmetry, vertical excess, airway/OSA, and patient preference after informed discussion.
- Presurgical orthodontics decompensates the dentition so the skeletal problem can be fully corrected; camouflaged incisors must be returned toward normal inclination.
- Procedures: Le Fort I (impaction, advancement, segmentation), BSSO (advancement or setback), genioplasty, SARPE for transverse maxillary deficiency, distraction osteogenesis, and TMJ surgery.
- Sequencing: single-jaw versus bimaxillary, and surgery-first protocols in selected cases; virtual surgical planning and 3D-printed splints are now standard.
- Stability: maxillary impaction is relatively stable; mandibular setback and large advancements are more prone to relapse. Condylar resorption risk rises in females with high mandibular plane angle and posterior rotation.
- Consent must cover neurosensory deficit, relapse, TMJ problems, and airway.
Worked example
A 23-year-old with Class III, ANB −6°, maxillary deficiency and mandibular excess, concave profile. The lower incisors are retroclined from camouflage. Reasoning: decompensate the lower incisors first, then plan bimaxillary surgery (Le Fort I advancement plus BSSO setback) with a splint; single-jaw surgery would not correct the maxillary deficiency.
Traps
- Operating on camouflaged teeth without decompensation.
- Ignoring the transverse dimension in surgical planning.
- Promising stability in high-risk condylar resorption cases.
- Failing to coordinate orthodontics and surgery dates.