Biomechanical evaluation of the temporomandibular joint following multi-directional orthognathic surgery: a finite element analysis.

This study investigated the biomechanical effects of multidirectional maxillary repositioning combined with mandibular advancement and rotation on temporomandibular joint (TMJ) components using patient-specific finite element analysis. Patient-specific three-dimensional models, reconstructed from the preoperative computed tomography (CT) data of six distinct patients presenting with varying dentofacial deformities, were used to generate the six virtual orthognathic surgery configurations, including isolated mandibular advancement, bimaxillary repositioning, vertical maxillary movements, and asymmetric rotational components. Under identical loading and boundary conditions, stress distributions in the condyle, articular disc, and glenoid fossa were evaluated. The results showed that isolated mandibular advancement produced higher and more asymmetric stress concentrations, whereas bimaxillary configurations resulted in lower and more homogeneous stress distribution. Vertical maxillary repositioning and rotational asymmetry increased unilateral and unbalanced joint loading. These findings suggest that bimaxillary surgical approaches may provide a more favorable biomechanical environment for the TMJ, while large mandibular advancements and rotational components should be planned cautiously because of their potential to increase postoperative joint loading.