Missing Posterior Occlusal Support and Temporomandibular Joint Disorders

Objectives: Aim of this study was to investigate whether a shortened dental arch (SDA), as identified by reduced posterior occlusal contacts, is a risk factor for the progression of temporomandibular joint (TMJ) intra-articular disorders (ID).
Methods: In this prospective observational multi-center study with a mean follow-up period of 7.9 years, a sample of 345 subjects with at least one temporomandibular disorder diagnosis at baseline was selected from community and clinical cases at the University of Minnesota, the University of Washington, and the University at Buffalo. Lack of occlusal posterior support was defined as no occlusal intercuspal contacts in the molar region on the left and/or right side corresponding to a SDA. The presence or absence of TMJ ID and the joints status were established by a calibrated, blinded radiologist at each site using bilateral magnetic resonance imaging (MRI) for soft tissue imaging for disc displacement (DD) and bilateral multidetector computed tomography (CT) or cone beam computed tomography (CBCT) for hard tissue imaging for degenerative joint diseases (DJD).
Results: Prevalence of TMJ ID at baseline ranged for the right TMJ from 7.3% for DD without reduction to 30.8% for DD with reduction and for the left TMJ from 5.9% for DD without reduction to 31.5% for DJD Grade 2, respectively. Missing posterior support was observed slightly more often in the participants’ left sided occlusion (11.7%) than in the right side (8.7%). At baseline, TMJ intra-articular status of both sides was not significantly affected by the presence of a SDA on the ipsilateral or contralateral side of the jaw. Furthermore, the presence or absence of an SDA at baseline was also not a significant predictor for a progression of the TMJ intra-articular status between baseline and follow-up.
Conclusions: Findings of this study suggests that there is no significant effect of SDA on TMJ ID.