Tinnitus, temporomandibular disorders and muscle activity: what's the connection?

This study was aimed at comparatively evaluating the relationship between temporomandibular disorder (TMD) and subjective tinnitus, as well as the effects of TMD treatment on masticatory muscle activity, tinnitus symptoms, and patient perception. In this prospective cohort study, patients diagnosed with both TMD and tinnitus were divided into groups with or without bruxism. The inclusion criteria were confirmed diagnosis of TMD and tinnitus. The exclusion criteria were history of prior TMD treatment, neurological disorders, or systemic diseases affecting muscle function. The primary outcome measures were electromyographic (EMG) assessments of masseter muscle maximum voluntary contraction (MVC) and the percentage of overlapping coefficient (%POC), determined via surface EMG (sEMG). The secondary outcomes included changes in tinnitus symptoms, assessed with the Tinnitus Handicap Inventory (THI), and pain levels, evaluated with the Visual Analog Scale (VAS). A total of 70 eligible participants were evenly distributed between groups. Tinnitus symptoms resolved in 35.7% of patients and did not significantly differ between groups (p > 0.05). Masseter MVC values decreased numerically but non-significantly after treatment (p > 0.05). In contrast, significant post-treatment improvements were observed in %POC, VAS, and THI scores (p < 0.05). Pre- and post-treatment comparisons of MVC, %POC, VAS, and THI revealed no significant intergroup differences (p > 0.05). TMD treatment appeared to effectively decrease subjective tinnitus symptoms and improve quality of life. Our findings suggest that TMD management might play an important role in tinnitus treatment and indicate that tinnitus is more associated with underlying internal disorders than with masticatory muscle activity directly influenced by bruxism.