The intensity of awake bruxism episodes is increased in individuals with high trait anxiety

Objectives Trait anxiety is associated with an increased occurrence of awake bruxism episodes, a behavior characterized by clenching of the teeth contributing to temporomandibular disorders in some individuals. Here we measured the activity of the masseter and the intensity and duration of spontaneous wake-time tooth clenching episodes in healthy individuals with different levels of trait anxiety (TA). Materials and methods Two hundred fifty-five individuals completed a web survey. Using their TA scores, we allocated them in low (< 20(th) percentile of the TA score distribution), intermediate (between 20(th) and 80(th) ), and high (> 80(th)) TA groups. We analyzed the electromyographic (EMG) activity of the right masseter during a 15-min silent reading task in forty-three individuals with low (n = 12), intermediate (n = 17), and high TA (n = 14). We tested between-group differences in EMG activity of the masseter, as well as postural activity-the muscular activity that maintains mandibular posture, and amplitude and duration of spontaneous tooth clenching episodes. Results The activity of the masseter (mean +/- SEM %maximum voluntary contraction/MVC) was greater in the high TA (10.23 +/- 0.16%MVC) than the intermediate (8.49 +/- 0.16%MVC) and low (7.97 +/- 0.22%MVC) TA groups (all p < 0.001). Postural activity did not differ between groups (all p > 0.05). The EMG amplitude of tooth clenching episodes was greater in the high TA (19.97 +/- 0.21 %MVC) than the intermediate (16.40 +/- 0.24%MVC) and low (15.48 +/- 0.38 %MVC) TA groups (all p < 0.05). The cumulative duration of clenching episodes was not different between groups (p = 0.390). Conclusions Increased TA is associated with both increased masseter muscle activity and intensity of wake-time tooth clenching episodes.

Automated summary

This study found that individuals with higher levels of trait anxiety exhibited increased masseter muscle activity and intensity of wake-time tooth clenching episodes. However, no between-group differences were found in postural activity and duration of tooth clenching episodes.