Intraoperative diagnosis of condylar sag after bilateral sagittal split ramus osteotomy

Purpose: To evaluate a method to identify condylar sag intraoperatively by clinical examination after bilateral sagittal split osteotomy (BSSO). Methods: We prospectively studied 184 patients (121 female, 63 male) who had BSSO. The same surgeon operated all patients over a period of 15 months using the same technique. All patients had mandibular advancements. A standard condylar seating technique was used. The occlusion was evaluated at operation and 1 week later. Results: Eighteen patients had an incorrect occlusion diagnosed during the operation after removal of the IMF. Peripheral condylar sag (type II) had developed in three of these patients. In 15 patients central sag was diagnosed. One-week postoperatively, three patients had a malocclusion as a result of condylar sag. Conclusion: Meticulous examination of the occlusion and an understanding of the occlusal changes secondary to condylar sag can reliably identify condylar sag intraoperatively. The use of suitable corrective measures during the primary operation can substantially reduce the postoperative complication rate of condylar sag.