Surgical mandibular advancement: a cephalometric analysis of treatment response.

Fifty-two cases of surgical advancement of the mandible were evaluated by retrospective cephalometric and computer analysis for longitudinal skeletal and dental changes an average of 3 1/2 years after surgery. Postsurgical treatment response appeared to be a multifactorial biologic phenomenon with considerable individual variability. Results showed generally good stability after mandibular advancement, with a minimal to moderate tendency toward skeletal relapse during intermaxillary fixation. Positional change of the proximal segment was the most important parameter in determining stability or relapse of the advanced mandible. Anteroinferior displacement of the condyle and increased posterior facial height were found to be important factors in the skeletal relapse observed during the period of intermaxillary fixation. The magnitude of mandibular advancement was a reliable surgical predictor of postsurgical relapse. Preoperative mandibular plane angle, postfixation intersegment instability, and patient's age cannot be isolated as being solely responsible for specific postsurgical changes.