Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia.

We aimed to compare the postoperative stability of conventional bimaxillary surgery (with bilateral sagittal split osteotomy) with that of maxillary impaction surgery (with mandibular autorotation without bilateral sagittal split osteotomy) in patients with skeletal class II retrognathia. Patients were assigned to have conventional bimaxillary surgery (conventional group, n=6) or mandibular autorotation (experimental group, n=7). Measurements were made using serial lateral cephalometric radiographs taken immediately preoperatively (T0), immediately postoperatively (T1), and one year later (T2) to assess the variation in operative change (T1-T0) and relapse (T2-T1). There was no significant difference in median (range) surgical change in the anterior movement at point B (conventional group, 4.5 (3.0-11.0) mm; experimental group 4.1 (2.1-6.4) mm). However, there was a significant difference in median (range) surgical posterior movement relapse at point B (conventional group -1.7 (-2.3 to -0.5) mm; experimental group -0.6 (-1.0 to 1.0) mm; p=0.032). Mandibular advancement with mandibular autorotation is therefore a more stable procedure than mandibular advancement with bilateral sagittal split osteotomy in patients with skeletal class II retrognathia.