抄録
The purpose of this study was to investigate biological signals during sleep associated bruxism. All night polysomnographic measurements were performed for twenty volunteers (mean age: 30.3 yrs, SD 5.7) at home. Polysomnographic data, involving masseter EMG, EEG, ENG, ECG, respiration and jaw movement was recorded using the multi-telemeter system.
Bruxism episodes were basically defined as elevation of masseter EMG activities above 5% MVC and then classified into clenching and grinding types due to their EMG and jaw movement patterns. The results were as follows:
1. The mean number of bruxism episodes was 38.7 per night, 6.1 per hour. The mean duration of bruxism was 8.8 sec, peak activity was 35.0% MVC and accumulated activity was 110.6% MVC·sec. Positive correlation was observed among duration, peak activity and accumulated activity of bruxism episodes (p<0.01).
2. Masseter muscle activity patterns during bruxism episodes did not always correspond to jaw movement patterns during episodes.
3. The sleep stage generally tended to rise lighter after bruxism episodes. The highest frequency of bruxism episodes was observed during sleep stage 2 followed by sleep stage REM, stage 1 and stage 3 in that order. No bruxism episode was observed during sleep stage 4.
4. Heart rate was gradually increased before a bruxism episode. The maximum heart rate was observed right after bruxism episode and then generally decreased thereafter.
