Bimaxillary surgery and temporomandibular joint hard tissue remodeling: a CBCT study on skeletal Class II and Class...

This study aimed to evaluate changes in horizontal condylar angulation (HCA), joint space distances (JS), condylar volume (CV), and degenerative alterations of the temporomandibular joint (TMJ) using preoperative and postoperative cone-beam computed tomography (CBCT) images of Class II and Class III malocclusion patients undergoing orthognathic surgery. This retrospective study included 148 CBCT images obtained from 74 patients who underwent bimaxillary surgery involving Le Fort I osteotomy and bilateral sagittal split ramus osteotomy. Patients were classified into Class II and Class III groups according to ANB angles. The patients' JS, HCA, and CV were measured, and degenerative changes observed in the condyle were recorded. Statistical analyses were performed using TURCOSA statistical cloud software. CV in Class II patients was significantly lower and HCA of Class II patients was higher in both periods (CV: p < 0.001/p < 0.001; HCA: p < 0.001/p < 0.05). HCA of Class III patients increased in the postoperative period (p < 0.001). In preoperative period, superior and posterior JS distances were significantly higher in Class II patients (p < 0.05/p < 0.05). All patients had a negative and significant correlation between HCA and CV (p < 0.05). In the postoperative period, sclerosis, osteophyte formation, and condylar resorption were observed significantly more frequently in Class II patients (p < 0.05/p < 0.001/p = 0.021). Different adaptive responses occur in the TMJ of Class II and Class III patients following orthognathic surgery. In Class II patients, postoperative reductions in SJS, PJS, and CV values, together with a higher incidence of degenerative changes, such as sclerosis, osteophyte formation, and condylar resorption, indicate an increased risk for TMJ health in this group. In contrast, the postoperative increase in HCA observed in Class III patients may be considered an adaptive alteration. Therefore, careful monitoring of TMJ health and the implementation of long-term follow-up strategies are clinically essential, particularly in Class II patients.