Reliability of a portable device for the detection of sleep bruxism

The aim of the study was to assess the repeatability in detecting sleep bruxism (SB) episodes by combined surface electromyography and heart rate (HR) signals recorded by a compact portable device (BruxoffA (R)). SB episodes are preceded by a sudden HR change. Thus, HR detection increases the precision of automatic detection of SB. Ten healthy subjects (five women and five men; 30.2 +/- 11.02 years) were selected for the study. Rhythmic masseter muscle activities, constituting the basic pattern of SB, were detected during three nights of recording during three different weeks with the Bruxoff device. The two-way ANOVA was not significant for SB episodes per night, SB episodes per hour, and heart frequency: no significant differences were observed during the three different nights of recording for each of the abovementioned variables (P > 0.05). The intraclass correlation coefficient showed a good reproducibility for SB episodes per night (69 %), SB per hour (74 %), and heart frequency (82 %). A poor reproducibility was revealed for the number of masseter contractions (53 %). The Pearson analysis showed the absence of a significant correlation between the number of masseter contractions per night and the number of SB episodes per night (r = -0.02, P = 0.91). The Bruxoff device showed a good reproducibility of measurements of sleep bruxism episodes over time. These findings are important in the light of the need for simple and reliable portable devices for the diagnosis of SB both in the clinical and research settings.