Associations between temporomandibular disorders and tinnitus - a systematic review

Objectives: Temporomandibular disorders (TMD) and tinnitus are highly prevalent conditions, that affects about 10-30% of the adult population and seem to co-exist. The primary objective of this systematic review was to investigate any associations between TMD and tinnitus. The secondary objective was to investigate if the associations differ between painful and non-painful TMDs. Methods: An electronic literature search in five databases was performed, from the inception of the databases until 26th of October 2022. This was to identify clinical trials with prevalence numbers of patients with TMD, with and without tinnitus and vice versa. From 1240 studies, a total number of 32 studies were included in the meta-analysis. A risk of bias analysis was made using the Methodological Evaluation of Observational Research (MORE). Results: Seventeen studies showed low risk of bias, while fifteen studies showed some risk of bias. Among patients with TMD, 57.5% also displayed tinnitus. In contrast, among patients with tinnitus, 92.9% also suffered from TMD. There was a strong association between patients with TMD that also had tinnitus, and patients with tinnitus that also had TMD (p's < 0.001). The odds ratio for TMD-patients also having tinnitus was 1.556 (p < .05), while it for tinnitus-patients also having TMD was 2.859 (p < .05). Six studies examined the psychological status, and there was a higher degree of psychosocial distress among patients with TMD and TMD/tinnitus. Conclusions: There is a strong significant association between TMD and tinnitus, but further research is needed to unravel the nature of this association and its clinical implication.