Time-variant nature of sleep bruxism outcome variables using ambulatory polysomnography: implications for recognition and therapy evaluation.

The aim of this study was to quantify the time-variant nature of sleep bruxism (SB) and to discuss its consequences. Six clinically diagnosed bruxers and six non-bruxers participated. Four ambulatory polysomnographic (PSG) recordings were obtained for every participant. As SB outcome variables, the number of episodes per hour of sleep (Epi h(-1)), the number of bursts per hour (Bur h(-1)) and the bruxism time index (BTI: the percentage of total sleep time spent bruxing) were established. To quantify the time-variant nature of SB, standard errors of measurement (SEMs) were calculated. For the non-bruxers, the SEMs for Epi h(-1), Bur h(-1) and BTI were 1.0, 5.7 and 0.1. For the bruxers, the respective values were 2.1, 14.9 and 0.4. In the discussion, arguments are given that because of the time-variant nature of the PSG recordings, cut-off bands around cut-off points might be useful for the recognition of SB.