Jaw tremor as a physiological biomarker of bruxism

Abstract

ObjectiveTo determine if sleep bruxism is associated with abnormal physiological tremor of the jaw during a visually-guided bite force control task. MethodsHealthy participants and patients with sleep bruxism were given visual feedback of their bite force and asked to trace triangular target trajectories (duration=20s, peak force <35% maximum voluntary force). Bite force control was quantified in terms of the power spectra of force fluctuations, masseter EMG activity, and force-to-EMG coherence. ResultsPatients had greater jaw force tremor at ∼8Hz relative to controls, along with increased masseter EMG activity and force-to-EMG coherence in the same frequency range. Patients also showed lower force-to-EMG coherence at low frequencies (<3Hz), but greater coherence at high frequencies (20–40Hz). Finally, patients had greater 6–10Hz force tremor during periods of descending vs. ascending force, while controls showed no difference in tremor with respect to force dynamics. ConclusionPatients with bruxism have abnormal jaw tremor when engaged in a visually-guided bite force task. SignificanceMeasurement of jaw tremor may aid in the detection/evaluation of bruxism. In light of previous literature, our results also suggest that bruxism is marked by abnormal or mishandled peripheral feedback from the teeth.