Development of Analysis System for Sleep Associated Bruxism

Objective: Bruxism is associated with forceful lateral or protrusive jaw movements. However, jaw movements during sleep associated bruxism were still unclear. The aim of this study is to establish the analyzing and diagnostic system for sleep associated bruxism using jaw movement data in six-degree-of-freedom.

Methods: For analysis of jaw movements during sleep, we developed a new light-weight electromagnetic six-degree-of-freedom jaw tracking device. The calibration study of this device was performed to record 100 samples in a 40x50x50 mm three-dimensionally grid with 10 mm spacing. Data from the jaw tracking device and the multi-purpose portable bio-amplifier recording device (Polymate AP1124; TEAC) were synchronized using a pulse generation method. We used these devices for measurement whole night jaw movements in 2 subjects (40 and 62 yrs old men) with standard sleep polysomnographic recordings, which included electroencephalogram, electrooculogram, electromyogram and electrocardiogram.

Results: The newly developed electromagnetic six-degree-of-freedom jaw tracking device using two intraoral small tri-axial coils (8x8x8 mm, 2g) allows us to record jaw movements in any posture and any condition even during sleep. The calibration study revealed the tracking resolution is not worse than 0.05 mm root mean square (rms) for translation, 0.1 degrees rms for rotation in the vicinity of the intercuspal position. Since the intraoral sensors were extremely small and light, they did not disturb subjects' sleep during measurement(sleep latency < 1min, sleep efficiency > 87%, %slow wave sleep > 6.0%, total sleep time > 6 hours). Furthermore, there was no contamination between both devices.

Conclusions: We could simultaneously record six-degree-of-freedom jaw movements and sleep polysomnographic data during sleep. This analyzing and diagnostic system for sleep associated bruxism was established for further study.

Supported: Knowledge Cluster Initiative that has been launched by the Ministry of Education, Culture, Sports, Science and Technology