Influence of inferior border cut on lingual fracture pattern during bilateral sagittal split osteotomy with splitter and separators: A prospective observational study.

Bilateral sagittal split osteotomy (BSSO) is a widely used orthognathic surgery technique. This prospective observational study investigated the correspondence between the planned inferior border cut and the actually executed inferior border cut during BSSO. The influence of the inferior border cut on lingual fracture patterns was also analyzed. Postoperative cone beam computed tomography (CBCT) scans of 41 patients, representing 82 sagittal split osteotomies, were investigated. The inferior border cut was intended to penetrate completely through the caudal cortex. Descriptive statistics were used to analyze the executed inferior border cuts. Mixed models were used to investigate the influence of independent variables such as the surgeon's experience on the inferior border cut. Secondarily the influence of the inferior border cut on lingual fracture patterns and the incidence of bad splits was assessed. The inferior border cut reached the caudal cortex in all cases, but reached the lingual cortex in only 38% of the splits. There was no significant relationship between the inferior border cut and a specific lingual fracture line. In this study, postoperative CBCT analysis revealed that the bone cuts during BSSO were often not placed exactly as planned. No significant relationship between the inferior border cut and lingual fracture patterns or bad splits was, however, detected.