Predictive Value of TMJ Tomographic Parameters for Hypermobility-Related Outcomes and Mouth Opening Capacity.

BACKGROUND

Temporomandibular joint (TMJ) hypermobility may be asymptomatic or may progress to hypermobility disorders, in which excessive condylar translation predisposes to clinical manifestations such as subluxation or luxation, including open-locking episodes. Although imaging provides structural parameters, its diagnostic value remains uncertain due to anatomical variability and inconsistent associations with symptoms.

OBJECTIVES

To evaluate the predictive value of tomographic features for TMJ hypermobility disorders and mouth-opening capacity.

METHODS

This analytical cross-sectional study included 150 adults (18-40 years) divided into control, dysfunction, painful and combined TMD groups, diagnosed using standardised criteria. Clinical outcomes included mouth-opening measures, open-locking history and TMJ subluxation diagnosis. Cone beam computed tomography (CBCT) measures comprised condylar angle, anterior and superior distances of the condyle and Boering classification. Imaging followed standardised protocols. Regression analyses were performed with age, sex, condylar angle, superior distance of the condyle and Boering classification as predictors, after verifying model assumptions.

RESULTS

CBCT variables showed bilateral symmetry and strong intercorrelations; only right-sided measures were retained. Multiple linear regression indicated that male sex predicted greater mouth opening across all measures, and superior distances of the condyle predicted greater assisted mouth opening. Binary logistic regression showed that older age reduced the odds of TMJ subluxation. Other imaging parameters were not significant, and the model for open-locking history lacked explanatory power.

CONCLUSION

Male sex was consistently associated with greater mouth opening, while imaging predictors showed only limited associations with functional measures. Age appeared protective against TMJ subluxation. CBCT parameters demonstrated limited predictive value for TMJ hypermobility-related outcomes.