The interrelationship of TMJ morphology, craniofacial structure, and airway dimensions in patients with disc displacement

Background: This study aimed to comprehensively analyse the interrelationships between temporomandibular joint (TMJ) morphology, craniofacial skeletal patterns, and oropharyngeal airway dimensions in patients with TMJ disc displacement (TMJ DD). Methodology: Based on the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and subsequent MRI confirmation, this retrospective study included 91 adult patients with TMD DD. These patients were then categorized into three groups.: Bilateral Normal disc position (BN, n = 36), Disc Displacement with Reduction (DDR, n = 25), and Disc Displacement without Reduction (DDWR, n = 30). All participants underwent cone-beam computed tomography (CBCT) and cephalometric analysis of craniofacial structure and three-dimensional assessment of TMJ morphology (including joint spaces, fossa dimensions, and condylar inclination) and oropharyngeal airway volume (OPV) and area (OPA). Statistical analyses included one-way ANOVA/Kruskal–Wallis tests for group comparisons, Spearman's correlation to assess bivariate relationships, and multiple linear regression (MLR) to identify independent predictors of airway dimensions while controlling for confounders. Results: Significant differences were observed in craniofacial, TMJ characteristics, and oropharyngeal airway dimensions among the groups. The DDWR group exhibited a retrognathic and hyperdivergent skeletal pattern (larger ANB, smaller SNB, higher FMA; p < 0.05). The DDR group demonstrated a significantly steeper anterior condylar inclination and a more posteriorly positioned condyle. Crucially, oropharyngeal dimensions were significantly smaller in the DDR group compared to the BN group (OPV: 7688.56 ± 1770.14 mm³ vs. 10,562.47 ± 4185.89 mm³, p = 0.029; OPA: 410.76 ± 77.65 mm² vs. 513.44 ± 145.21 mm², p = 0.018). Correlation and MLR analyses revealed that a constricted airway was associated with mandibular retrognathism, specific TMJ features, and reduced vertical facial dimensions. Notably, glenoid fossa height was a significant positive predictor for both OPV and OPA. Conclusions: TMJ DD is associated with specific craniofacial patterns and reduced oropharyngeal airway dimensions. These findings underscore a significant association within the TMJ-craniofacial-airway complex, advocating for an integrated clinical approach in diagnosing and treating temporomandibular disorders and airway compromise.