Abstract
Purpose: To establish a simple and reliable method for assessment of sleep bruxism (SB) in clinical dentistry, we have developed an ultraminiature cordless electromyogram system, BMS. We have examined the validity of the BMS in an awake state in the daytime and the influence of motion of simulated sleep-turning and scratching motion on the device. In the present study, as a preliminary step to practical application of the device to SB assessment, we examined whether EMG activities could be properly recorded without significant trouble by using the BMS in an actual home sleep environment.
Methods: The subjects were nine bruxers and nine non-bruxers. EMG activities of the masseter muscle during sleep were measured by using the BMS for two days in the subjects' homes. The data obtained during the second night were analyzed and compared between the two groups. EMG bursts with amplitude of 20% of maximum voluntary contraction (MVC) or more and with duration of 0.25s or more were selected. Start and end of the sleep period were detected by using an actigraph. (AMI Ltd.)
Results: All subjects could set up and operate the BMS by themselves. The EMG bursts obtained by using the BMS during sleep could be properly recognized and analyzed. Artifact signals with a linear-spike shape, which were thought to be radio wave communication errors, were occasionally observed, but the signals could be distinguished from actual muscle activities and were eliminated. The number of bursts, burst time and integration of bursts per hour of sleep period of bruxers were significantly larger than those of non-bruxers, and the mean values in bruxers were 6.3-times, 3.2-times and 2.5-times larger, respectively, than those in non-bruxers. The duration per burst of bruxers was significantly smaller than that of non-bruxers. There was no significant difference between the two groups in the average of RMS values of burst and sleep time.
Conclusion: It was confirmed that masseteric EMG burst during sleep in the home environment could be properly recognized and analyzed both in bruxers and non-bruxers in BMS measurement. The BMS is thought to have capacity for practical use as a monitoring device of masseteric activity during sleep.
