Comparison of joint space volume according to the status of temporomandibular joint internal derangement

OBJECTIVE: To evaluate cone-beam computed tomography (CBCT)-based three-dimensional joint space volume according to magnetic resonance imaging (MRI)-defined temporomandibular joint (TMJ) internal derangement (ID). METHODS: Ninety-one TMJs from 48 patients were classified as normal, anterior disc displacement with reduction (ADcR), or without reduction (ADsR). CBCT-derived volumes were compared using linear mixed-effects models, with additional adjustment for age, sex, osseous degeneration, and joint pain. RESULTS: Unadjusted analyses showed significant group differences in total joint space, condylar, glenoid fossa, anterior, and medial joint-space volumes. After multivariable adjustment, no volumetric outcome showed a significant overall between-group difference. CONCLUSION: CBCT-derived volumetric differences were observed among MRI-defined disc displacement groups but were attenuated after adjustment for demographic and clinical factors. CBCT may provide complementary information on TMJ morphology but cannot directly assess disc position and should not replace MRI.