Features of the bioelectric activity of the masticatory and temporal muscles proper in patients with different levels of anxiety with dysfunction of the temporomandibular joints

Abstract

The aim of the study was to investigate the functional activity of the masticatory and temporal muscles according to surface electromyography (EMG) data at rest and with maximum clenching of the teeth in patients with different levels of personal and situational anxiety, suffering from dysfunctional disorders of the temporomandibular joint (TMJ).
Materials and methods.
The study involved 45 patients, 33 women and 12 men aged 19 to 36 years. The main cohort consisted of 33 patients with signs of dysfunction of the TMJ and masticatory muscles, the comparison group — 12 participants without signs of functional disorders. Based on the results of TMJ MRI, the patients of the main cohort were divided into 3 groups: I — 12 patients with dislocations of the TMJ articular discs without reposition; II — 10 patients with dislocations of the TMJ articular discs with reposition; III — 11 patients without intra-articular changes of the TMJ, but with clinical manifestations of muscle dysfunction (extra-articular dysfunction). To determine the level of anxiety in all participants, the Spielberger—Khanin method was used. Using EMG of the temporal and masticatory muscles, the maximum and average amplitude of bioelectrical activity of the masticatory muscles in a state of physiological rest and jaw compression were measured, the symmetry index of the temporal muscles and the symmetry index of the masticatory muscles were calculated.
Results.
In patients with dysfunction of the TMJ and masticatory muscles, the levels of situational and personal anxiety were 3.5—3.9 and 3.5—3.8 in group I, 3.5—3.9 and 3.5—3.8 in group II, 2.5—2.8 and 2.3—2.9 in group III, which was significantly higher compared to the anxiety levels of patients in the comparison group (1.5—1.9 and 1.3—2.0; p<0.01). The maximum and average amplitudes of biopotentials of the temporal and masticatory muscles in patients with TMJ dysfunction and masticatory muscles (850—911 and 55.4—58.3 mV at rest, 1289—1398 and 372—380 mV during jaw clenching, respectively) were significantly higher than the corresponding amplitudes of biopotentials of these muscles in patients of the comparison group (631—690 and 15.4—18.3 mV at rest, 954—1063 and 312—320 mV during clenching, respectively; p<0.01). In patients of groups I and II with intra-articular TMJ disorders, the most pronounced imbalance of functional activity between the masticatory muscles of the right and left sides was observed. The symmetry index of the temporal muscles in patients of groups I and II (80—81.2 and 77.7—103%) was significantly lower than in patients of groups III and IV (85—85.5 and 85.7—93.7%; p<0.01). The symmetry index of the masticatory muscles in patients of groups I and II (95.2—100 and 98.6—100%) was also significantly lower than in patients of groups III and IV (100%; p<0.01).
Conclusion.
 Patients with dysfunction of the TMJ and masticatory muscles have increased and asymmetric bioelectrical activity of the masticatory muscles. In this regard, it is recommended to conduct EMG of the masticatory muscles to monitor the functional activity of the masticatory muscles and assess the effectiveness of therapeutic measures. In addition, it is recommended to conduct psychological testing of patients with TMJ dysfunction to determine the level of anxiety in order to include the help of a psychologist or psychotherapist in a comprehensive treatment plan.