Byoung-Ho Kim

Director, Smile Future Orthodontic Clinic, Seoul, Korea
Clinical instructor, Department of Orthodontics, Seoul National University Dental Hospital

The orthognathic surgeries in class II malocclusion are less prevalent than that in class III malocclusion in Korea. It is because retrognathic profile is more traditionally acceptable than prognathic profile in Korea. And the compromised treatment using orthodontic mini-screw overcomes the skeletal discrepancies to some degree and brings out acceptable results. High relapse tendency reported in class II malocclusion surgery cases is also one of the causes avoiding the orthoganthic surgery in class II malocclusion.

Nevertheless in cases of class II malocclusion with severe skeletal discrepancy, orthognathic surgeries are inevitable. In order to get successful results we need to consider following factors.
1) Maxillary vertical dimension
- Since the mandibular position is determined by 3-dimensional orientation of the maxilla, we have to consider the maxillary position first in order to correct the mandibular position effectively.
2) Inclination of maxillary occlusal plane to FH plane
- According to the FH/maxillary occlusal plane angle, we can diversify the direction of rotation of maxiillo-mandibular complex.
3) Inclination of lower incisors
- It can determine whether to extract premolars or not. For class II cases, lower incisor inclination and mentolabial fold are the points of esthetics.
4) A-P position of maxilla
- It can determine whether the maxillary setback is necessary or not.
5) Relapse tendency
- TMJ is the critical factor in stability and relapse in class II surgery. So we need to avoid treatment procedures which can lead to increased risk of joint remodeling.

I would like to present how to design surgical planning in various patterns of skeletal class II cases and what to do to prevent relapse after surgery as follows.

1. Host factor
2. Pre-op orthodontic treatment: stable surgical occlusion
3. Stabilizing condylar position
4. Surgical planning
5. Post-operative functional remodeling of condyle