Relationship of bruxism and sleep health of children in Japan

Objectives: Resent studies suggest that children with prominent bruxism have a higher arousal index, which may be associated with an increased incidence of attention-behavior problems. In Japan, it have attracted public attention as social issues that behavioral problems in children and decline in their academic ability caused by worsening sleep health. Sleep bruxism has been reported in up to 20% of children younger than 11 years of age. Additionally, in most of children, considerable grindings are seen in the clinical oral examination. However, there are few epidemiology studies regarding sleep bruxism of children in Japan. In the present study, we, therefore, investigated relationship between sleep bruxism and sleep health including life styles.

Methods: The elementary school students' parents in country area (Yamanashi Prefecture, n=159) and in megalopolis (Tokyo, n=4617) have answered the questionnaires including the 5 factors about sleep health and life styles. Sleep bruxism was evaluated by the BruxChecker, simplified device, which has been attached to the children (n=190) during a night with informed consent.

Results: In a country area, the severe bruxism group showed a better quantitative score of “Feelings of Sleep Maintenance” and “Sound Sleep” than the mild bruxism group. Sleep time of the lower grade children in the megalopolis was longer than that in the country area, implying a tendency of a higher frequency of the severe bruxism group.

Conclusion: Contrary to our expectation, the present study found that the severe bruxism in lower grade children is related with better sleep health and quality suggesting that the disappearance of inhibitory control in upper level for involuntary movement during sleep might occur in lower grade children having sound sleep.

This work was supported by a MEXT sponsored project.