Physiological positioning strategy alters condylar position after mandibular ramus sagittal split osteotomies for mandibular prognathism.

OBJECTIVE: The aim of this study was to elucidate the physiological position of the proximal segment for postoperative jaw movement in patients with mandibular prognathism. METHODS: Twenty-two patients with mandibular prognathism were treated by orthognathic surgery using bilateral mandibular sagittal split ramus osteotomies (SSRO) with a physiological positioning strategy. The skeletal stability was assessed, and the movement of the proximal segment was evaluated by cephalography and computed tomography performed preoperatively, immediately postoperatively, and one year postoperatively. RESULTS: The patients were divided into two groups: the stable group (SNB relapse <1.5 degrees ) and the relapse group (SNB relapse >/=1.5 degrees ). In the stable group at one year postoperatively, the average SNB relapse was only 0.29 degrees (7%), the condylar head had moved posteriorly by 0.75 mm, and the proximal segment had rotated counterclockwise by 1.2 degrees . CONCLUSION: This new physiological positioning strategy improves the position of the condyle compared with the preoperative position in patients with mandibular prognathism.