U-HRCT and MRI-Based Indicators for Limited Mouth Opening in Patients With Temporomandibular Disorders

Background Limited mouth opening (LMO), a manifestation of temporomandibular disorders (TMD), severely impairs masticatory function, speech, and quality of life. This study aimed to identify ultra-high-resolution computed tomography (U-HRCT) and magnetic resonance imaging (MRI)-based indicators of LMO, and to develop a diagnostic model for LMO. Methods A total of 226 TMD patients (median age 25.00 years; 81.4% females) with 452 temporomandibular joints (TMJs) who underwent U-HRCT and MRI scanning were retrospectively enrolled. Clinical features (age, sex, maximal mouth opening, and parafunctional oral habits) and imaging features (condylar bone morphology, morphological parameters, and disc position) were analysed by univariate and multivariate generalized estimating equation analyses to identify independent indicators of LMO. All patients were randomly assigned to training and testing sets at a ratio of 7:3. Receiver operating characteristic curve with area under the curve (AUC), calibration curve, and decision curve analysis (DCA) were used to evaluate the performance of the model. Results Age, condylar flattening, condylar head height, and anterior disc displacement without reduction were chosen as indicators for LMO and used to construct the model. The training set showed 0.764 of AUC (95% CI, 0.697-0.832) and testing set showed 0.744 of AUC (95% CI, 0.648-0.840) in diagnosing LMO. Calibration curves showed good consistency, and DCA confirmed positive net benefit across clinically relevant thresholds. Conclusions This U-HRCT and MRI-integrated model showed potential for individualised LMO risk stratification in TMD patients. The model underscores the synergistic value of multimodal imaging biomarkers and may facilitate a personalised management strategy.