Progression of TMD is Not Associated With Occlusal Discrepancies

Objectives: Occlusal discrepancies continue to be considered important precipitating factors for the development of different subtypes of temporomandibular disorders (TMD). We proposed to examine the relationship between occlusal factors and the progression of TMJ intra-articular disorders and pain.
Methods: This study included healthy subjects and patients with TMD (n=390). At baseline (T1), RDC/TMD Axis I diagnoses were established by consensus of 2 TMD experts and a radiologist based on a comprehensive clinical exam, surveys, bilateral CT scans, and MRIs. Progression of the intra-articular joint diagnosis and pain intensity was assessed nine years (T2) after T1 using questionnaires, physical exam and bilateral TMJ MRI and CT scans. Three groups were established according to the progression of joint diagnosis: 1-unchanged/improved (n=186); 2-One TMJ worsened (n=134); 3-Two TMJs worsened (n=70). Eight occlusal factors were compared between the groups (overjet, overbite, missing teeth, anterior and/or posterior open bite, posterior crossbite, occlusal contacts, CR-CO discrepancy) using ANOVA and Chi-square test. Person’s correlation was used to assess the progression of TMJ DJD and pain.
Results: Although we found differences in overjet, number of missing teeth and occlusal contacts between the groups at baseline, these variables were not directly correlated to the severity of the TMD. At T2 no difference was observed in the occlusal characteristics between the subjects that had an improvement in their TMJ diagnosis and those who experienced progression of the TMJ disc displacement or DJD. Progression of TMJ pain at T2 was not associated with any occlusal feature.
Conclusions: The progression of TMD articular diagnosis or pain intensity does not seem to be influenced by the presence or absence of any occlusal discrepancies. TMD progression is a dynamic process including amelioration in some of individuals.