Electrophysiological Study of the Masticatory Muscle Activity in Patients With Temporomandibular Disorders With and Without Tinnitus

Objectives: The relationship between tinnitus and temporomandibular disorders (TMD) over the years has continued to be widely debated in literature and not yet fully understood. Several causes have been associated with tinnitus including altered mandibular posture and disorders at the muscle, joint and periodontal receptors. This study aimed to investigate masseter and temporalis muscle activity in patients with TMD with and without somatosensory tinnitus (ST). Material and Methods: A total of 105 patients (mean age 50.49 ± 11.7 years) with TMD classified according to Axis I DC/TMD diagnostic criteria were enrolled and then divided into two groups: 53 subjects with ST and 52 without ST. Electromyographic and kinesiographic instrumental examinations were used for data collection. Statistical analyses, including Levene's test and independent t-test, were performed to evaluate and compare muscle activity abnormalities between the two groups. Results: The study showed a higher incidence of abnormal masticatory muscle activity in habitual resting position in TMD without ST patients compared to those with TMD and ST. A statistically significant difference in muscle activity between the two groups was observed. Conclusions: The results suggest a potential link between masticatory muscle activity and tinnitus in TMD patients. Neuroplasticity may play a role in modulating the psychoacoustic characteristics of tinnitus.