The biomechanical effects of bilateral sagittal split ramus osteotomy and bimaxillary osteotomies to the patients with maxillofacial deformities under incisal clenching.

ABSTRACT

OBJECTIVE: Bilateral sagittal split ramus osteotomy (BSSRO) and bimaxillary osteotomies (BSSRO plus Lefort1 osteotomy) are widely used to solve maxillofacial deformities. The effect of the surgeries on the temporomandibular joint (TMJ) is still not clear. The purpose of this study was to investigate the preoperative and postoperative stress environment of the patients and to compare the biomechanical differences of the two surgeries. METHODS: Ten patients were performed BSSRO and fourteen underwent bimaxillary osteotomies. Eleven asymptomatic subjects were recruited to be the control group. The muscle forces of incisal clenching were applied on the finite element models. And contact was used to simulate the interactions within the TMJs. RESULTS: two kinds of surgeries could not completely eliminate the negative biomechanical distribution within the TMJs. CONCLUSION: Compared to BSSRO only, the bimaxillary osteotomies could better repair the biomechanical environment of the TMJs under incisal clenching. And the TMD symptoms were strongly related to the stress distributions of the TMJs.