Comprehensive assessment of mandibular condyle adaptation following mandibular advancement versus mandibular setback surgery

Abstract Objective This study aimed primarily to evaluate three-dimensionally the alteration in the temporomandibular joint (TMJ) at short- and long-term follow-up after mandibular advancement (MAS) and mandibular setback (MSS) surgeries; secondarily to compare these changes between the two surgical interventions. Materials and methods Forty-six patients (92 TMJs) were analyzed: 23 patients underwent MAS, and 23 patients received MSS. Computed tomography scans were obtained preoperatively (T0), within one week postoperatively (T1), and at two years postoperatively (T2). A validated three-dimensional TMJ assessment protocol, encompassing condylar position, inclination, dimensions, joint spaces, intra-articular alignment, and volumetric joint space was applied, and appropriate statistical tests were used to compare changes across time intervals and between the two interventional groups. Results In the MAS group, the mediolateral inclination angle of the right condyle significantly changed from T0 to T1 by 5.56 ± 0.9°, then increased at T2 with a mean long-term change of 0.59 ± 0.14°. Condylar height on the left side also decreased significantly (p = 0.020). Superior (SJS) and posterior joint spaces (PJS) of the left TMJ were reduced by 1.18 ± 0.23 and 0.72 ± 0.29 mm, respectively, whereas in the MSS group, only the anterior joint space (AJS) of the right TMJ increased between T1 and T2 by 0.24 ± 0.09 mm. Volumetric joint space decreased significantly after MAS and remained stable after MSS. No significant changes were reported between the two types of surgeries, except for AJS, SJS, mediolateral condylar position, and anteroposterior condylar position (p < 0.05). Conclusion MAS showed measurable condylar positional changes, mainly lateral inclination and mild posterior displacement, whereas MSS demonstrated smaller within-group changes. However, inter-group analyses indicated greater changes in selected TMJ parameters after MSS than MAS. These findings, based solely on radiographic assessments, warrant cautious interpretation.