Comparison of Jaw Muscle EMG Activity in Awake and Sleep Bruxers

Objectives: Background: Bruxism has two different circadian manifestations (awake and sleep) that have been proposed to have different underlying pathophysiology.
Objectives: To compare the characteristics of multiple days EMG assessment of the anterior temporalis muscles between patients with self-reported awake bruxism, sleep bruxism and healthy individuals.
Methods: Methods: Participants with possible sleep bruxism (n=9) or awake bruxism (n=9) bruxism were included in an open study and compared with healthy individuals during awake (n=9) and sleep (n=7) states. All participants were assessed for a minimum of 4 days (awake or sleep) with a portable single-channel EMG recorder. The outcome parameters of the anterior temporalis EMG activity were bursts, duration and episodes per hour. The EMG activity for the first 30 min of recording was discarded to avoid contamination with intentional EMG activity and periods with chewing were omitted from the data set. To allow a direct comparison, jaw muscle activity during a 4-hr awake and a 4-hr sleep period was contrasted. Outcome parameters were compared using ANOVA.
Results: Results: Overall, there was a significant effect of bruxism diagnosis and circadian manifestation on EMG bursts and episodes (P<0.04). Post-hoc analyses showed that awake bruxism was associated with significantly higher EMG activity when compared against both healthy individuals during awake or sleep states and possible sleep bruxers (P<0.02).
Conclusions: Conclusion: This study demonstrates a remarkable high EMG activity in patients with possible awake bruxism Further studies will be needed to characterize the intensity and duration of the jaw muscle activity in different populations of self-reported bruxers and non-bruxers.