Posterior mandibular widening secondary to advancement sagittal split osteotomy: A retrospective study.

Introduction: Patients sometimes spontaneously report a modification of the width of their lower face after an advancement bilateral sagittal split osteotomy (ABSSO). The main goal of our study was to assess the variation of the bigonial distance (BGD) before and after ABSSO in a group of patients. The second goal was to look for a possible relation between the variation of BGD and the amount of mandibular advancement.

Materials And Methods: We conducted a retrospective radiological study on patients who underwent an isolated ABSSO (Obwegeser-Dal Pont II type osteotomy) for a class II malocclusion in our department over a 26 months period. The measures were made on standardized frontal and lateral teleradiographies taken before, one day and one year postoperatively.

Results: Fifty patients (36 females, 14 males; mean age: 24) could be included. BGD was significantly increased one day (+9.8mm, P<10(-3)) and one year after surgery (+4mm, P<10(-3)). There was no relation between the amount of mandibular advancement and the increase of BGD.

Discussion: Our results suggest that ABSSO is responsible for posterior mandibular enlargement which must be taken into account during the aesthetic preoperative assessment. Further studies are mandatory to identify the risk factors for this phenomenon.