Evaluation of skeletal stability following surgical correction of mandibular prognathism

This retrospective study was designed to assess skeletal stability after th e correction of mandibular prognathism by sagittal split osteotomy (SSO) an d intraoral vertical subsigmoid osteotomy (VSO), We used lateral cephalogra phs of 31 patients taken before, immediately after, and at least one year a fter the operation. We recorded euclidean distance matrix analysis, linear and angular measurements, and x and y co-ordinates of cephalometric landmar ks for each cephalograph, There were no significant differences in extent o f the mandibular retrognathia or magnitude of change between the two groups . The main significant changes in both groups were reduction of the total m andibular length, and posterior shifting in the mandible. One year after th e operation the main change was the mean forward relapse of 2.5 mm in the S SO group and the mean posterior relapse of 0.5 mm in the VSO group, The dif ference in skeletal stability between the groups was significant (P < 0.05) , and we conclude that VSO is the more effective technique for correcting m andibular prognathism.