Byoung-Ho Kim

Smilefuture orthodontic clinic

We can observe various skeletal changes after orthognathic surgery in the short term and also in the long-term. There are several factors which influence on post-surgical skeletal changes as follows,
1. Facial pattern
2. Force of masticatory muscles
3. Stability of immediate post-surgical occlusion
4. Surgical techniques such as osteotomy and fixation methods
5. Stability of mandibular condyle
Each factors can influence on changes of occlusion immediately after surgery, but it can also produce long-term changes of occlusion and profile gradually. To get predictable and successful result, we have to consider those factors in treatment planning stage.
Especially, the activity of masticatory muscles consistently influences on skeletal change after surgery immediately and also in the long term. Dr. Ellen Ko reported that larger sagittal relapse of mandibular setback occurred in patients with greater masticatory muscle activity, and modifications in surgical design and overcorrection should be considered in patients with greater masticatory muscle activity in orthognathic surgery.
During post-operative orthodontic treatment, occlusion settles down, mandible rotates upward and forward, and anterior facial height tends to be reduced. Therefore stronger masticatory muscle activity can produce larger post-operative skeletal changes. Dr. Kenji Yoshida reported that a significant correlation between facial type and relapse pattern was confirmed at the long-term assessment of prognosis. In case of brachyfacial pattern, more clockwise pattern of relapse occurs post-operatively.
For stable surgical results, we have to consider following factors differently according to the facial pattern.
1. Surgical occlsuion
2. The amount of overcorrection in vertical and horizontal dimension
3. Various techniques of osteotomy
4. Process of post-operative orthodontic treatment