Structural characteristics of the temporomandibular joint in temporomandibular joint disorder syndrome: a preliminary cross-sectional study based on MRI

Temporomandibular joint disorder syndrome (TMD) is a prevalent oral-maxillofacial condition. The Diagnostic Criteria serve as a widely used diagnostic framework for TMD with high specificity, yet its sensitivity requires further optimization. In contrast, magnetic resonance imaging (MRI) is a non-invasive imaging modality that enables clear visualization of temporomandibular joint (TMJ) structures. Therefore, this study aimed to analyze the association between TMJ structural characteristics and TMD, and evaluate the relationship of MRI-based morphological parameters with TMD. Two hundred sixty-one patients (522 joints) were enrolled in this study from our dataset and divided into a TMD group (143 patients) and control group(118 patients). MRI was used to measure anteroposterior diameter (AP), mediolateral width (ML), condyle length (CL), morphology, anterior joint space (AJS), superior joint space (SJS), posterior joint space(PJS), condylar position, horizontal condylar angle (HCA), and the inclination of the glenoid fossa (IGF). The difference of those structural parameters between two groups was compared, and multivariable generalized estimating equations (GEE) was used to identify the association of the parameters with TMD, accounting for within-patient correlation of bilateral joints. The TMD group showed significantly smaller condylar dimensions, altered joint space, and higher proportions of beak-like condyles and posterior condylar position (all P < 0.05). Multivariable GEE analysis showed that smaller AP/CL, narrower SJS, round/flattened morphology, and anterior/concentric position were negatively associated with TMD, while wider AJS/PJS(all P < 0.05), were positively associated with TMD, whereas HCA and IGF showed no significant associations. Reduced condylar size, altered joint space, specific morphological and positional features are associated with TMD. Quantitative MRI measurements may help characterize TMJ structural features related to TMD.