Assessment and comparison of proximal segment changes following mandibular set-back through bilateral sagittal split ramus osteotomy and intraoral verticosagittal ramus osteotomy

Proximal segment movements following different methods of ramus osteotomy is one of the undesired consequences of orthognathic surgery. Theoretically, it seems that intraoral verticosagittal ramus osteotomy can minimize the movement of proximal segment. In this study, changes in intergonial distance and ramus flaring angles were evaluated and compared in transverse plane after mandibular set back by two osteotomy techniques. In this randomized clinical trial 20 patients with mandibular prognathism without any asymmetry were selected and divided into two groups of 10 each.One group was treated by bilateral sagittal split ramus osteotomy and the other by intraoral verticosagittal ramus osteotomy technique. Intergonial width and inner ramal angle in transverse plane were measured on radiographs before and 1 and 12 weeks post surgery. Data were analyzed using covariance test with P<0.05 as the level of significance. Changes of intergonial distance and interramal angle in each group were significant after 1 and 12 weeks after surgery. No statistically significant difference was observed between the two studied groups. According to the results of this study, there is no difference between bilateral sagittal split and intraoral verticosagittal ramus osteotomy techniques regarding mandibular width and ramus flaring changes.