Variability of sleep bruxism—findings from consecutive nights of monitoring

OBJECTIVES: To determine sleep bruxism (SB) behavior during five consecutive nights and to identify correlations between SB episodes per hour (SB index) and sleep-time masseter-muscle activity (sMMA). MATERIAL AND METHODS: Thirty-one participants were included in the study. Of these, 10 were classified as sleep bruxers (group SB-1) and nine as non-sleep bruxers (group non-SB). The bruxism status of these 19 patients was identified by means of questionnaires, an assessment of clinical symptoms, and electromyographic/electrocardiographic data (Bruxoff® device). The remaining 12 participants were also identified as bruxers, but based exclusively on data from the Bruxoff device (group SB-2). Data analysis included descriptive statistics and Spearman's correlation to assess the relationship between the SB index and sMMA. RESULTS: Participants in group SB-1 showed an overall mean SB index of 3.1 ± 1.6 and a mean total sMMA per night of 62.9 ± 38.3. Participants in group SB-2 had an overall mean SB index of 2.7 ± 1.5 and a mean total sMMA of 56.0 ± 29.3. In the non-SB group, participants showed an overall mean SB index of 0.8 ± 0.5 and a mean total sMMA of 56.8 ± 30.3. Spearman's correlation yielded values of - 0.27 to 0.71 for the correlation between sMMA and SB index. CONCLUSIONS: The data revealed variable SB activity and the absence of a reliable correlation between sMMA and the SB index. CLINICAL RELEVANCE: The high variation in SB activity and lack of correlation between sMMA and the SB index should be considered when diagnosing SB. TRIAL REGISTRATION: Clinical Trials NIH, clinical trial no. NCT03039985.