Figure 7

Differences in bone segment interference based on whether the mandible was set forward or back. In skeletal Class II, the interference was more likely to occur at the posterior margin of the distal segment if the distal segment moves forward. If the interference occurs, it rotates around the interference site, displacing the anterior margin of the proximal segment outward and the condyle inward (Fig. 7A). This phenomenon is occasionally difficult to prevent because it is challenging to identify directly during surgery. By contrast, in skeletal Class III, the condylar head is not extremely small originally compared with the mandibular fossa. Moreover, the condylar head is less likely to be displaced. Furthermore, the bony interference is more likely to occur at the anterior margin of the proximal segment, which is easier to detect directly during surgery and less likely to be displaced (Fig. 7B).