Influence of motion and posture of the head on data obtained using the newly developed ultraminiature cordless bruxism measurement system

Purpose: To elucidate the influence of motion and posture of head on the newly developed ultraminiature cordless bruxism measurement system (BMS), we examined masseteric electromyographic (EMG) data of BMS during turning-over movements in bed in comparison with those of a conventional polygraph system (PG). Methods: Twelve healthy subjects lay on their back and then turned to the right (right turn, 908) and then to the left (left turn, 1808). Maximum amplitudes and root mean square (RMS) values of EMG data were calculated during the phase of turning movements. The data were high-pass filtered at 10 Hz, 30 Hz, 50 Hz, and 100 Hz. Results: Artifact signals were visibly observed in PG measurement for all subjects and in BMS measurement for three subjects. Maximum amplitudes during right turn measured by BMS were significantly smaller than those measured by PG, while there was no significant difference during left turn. During right turn, RMS values high- pass filtered at 10 Hz obtained by BMS were significantly smaller than those obtained by PG, while there was no significant difference between the data obtained by the two devices at the other cut-off frequencies. During left turn, there was no significant difference between RMS values obtained by the two devices. Conclusions: Although BMS data were slightly affected by motion and posture of head during simulated sleep-turning, it was suggested that motion artifact of signals during BMS measurements is equivalent to or less than that during PG measurements, and BMS is thought to be suitable to measure sleep bruxism. (C) 2009 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.