Predictive Value of Diagnostic Methods for TMJ Hypermobility in the Associated Clinical and Functional Features of Temporomandibular Disorders: A Regression Study.

BACKGROUND

Joint hypermobility (JH), particularly at the temporomandibular joint (TMJ), has been proposed as a potential risk factor for temporomandibular disorders (TMD). However, its heterogeneous diagnostic approaches (clinical, anamnestic and imaging) limit the identification of reliable predictors of masticatory dysfunction and TMD outcomes.

OBJECTIVES

To determine which diagnostic methods for TMJ hypermobility best predict masticatory dysfunction and the clinical and functional repercussions of TMD.

METHODS

This cross-sectional study included 126 adults recruited at the Bauru School of Dentistry. Participants were classified by Diagnostic Criteria for TMD (DC/TMD) into painful, dysfunction or combined groups, balanced by history of open-locking. Assessments comprised DC/TMD and ICOP examinations, symptom intensity on the visual analog scale (VAS), Beighton score, pressure pain thresholds, bite-force and fatigue tests, ultrasound of the TMJ capsule and masseter, CBCT-based condylar angle and validated measures of mandibular function and psychosocial factors.

RESULTS

Bivariate analyses yielded associations, but multivariate models identified specific predictors. Open-locking independently predicted TMJ subluxation and higher joint instability. Increased condylar angle was associated with greater assisted opening and midline deviation. Unassisted opening predicted a larger condylar angle, greater pain-free opening and lateral condylar jump; assisted opening similarly predicted pain-free opening and lateral condylar jump. Lateral condylar jump independently predicted functional limitation in wide-opening tasks.

CONCLUSION

Clinical, functional and imaging indicators of TMJ hypermobility capture distinct aspects of the condition. While open-locking, condylar angle and mouth-opening measures predict specific features, no single marker explains the full spectrum and TMJ hypermobility shows limited impact on overall TMD outcomes.