Life science
Healthcare, Dentistry

Pathophysiology of sleep bruxism in children
Department of Oral Physiology, Graduate School of Dentistry
Professor Takafumi KatoResearchmap https://researchmap.jp/read0111598_hrfc15

Life science

Abstract
Tooth grinding is reported by 20％ of children. However, pathophysiology of Sleep bruxism (SB) in children remains to be clarified. In this study, polysomnographic recordings were done in 44
healthy children in sleep research laboratory. Then, sleep depth
and autonomic activity were quantified, and tooth grinding andarousals were scored. The values were compared between children with or without tooth grinding. Approximately 27% of children
was diagnosed as having SB. Tooth grinding was found to occur inthe cluster in the light NREM sleep during the transition from deep
NREM sleep to REM sleep. The periods were characterized by thedecrease of delta EEG power, the raise in sympathetic activity andthe increase of arousals. Tooth grinding was also associated withcortical and movement arousals. Therefore, the study first documented in children that the occurrence of tooth grinding is fluctuated in relation to physiological changes within sleep cycles.

▍ Background & Results
Sleep bruxism is characterized by the frequent occurrence of
tooth grinding during sleep. Prevalence of tooth grinding is approximately 20% in children. Severe and frequent tooth grinding can beassociated with tooth wear and orofacial pain in children. However,
the mechanism of tooth grinding has not been clarified. In addition,
no appropriate diagnosis and treatment have been established.
To elucidate the mechanisms of sleep bruxism, we need to collectmultiple physiological data from healthy children, and analyze thephysiologic changes in relation to jaw muscle EMG activity. However, the research in children has not progressed at all due to thedifficulties in recruiting and recording children in sleep laboratory
and the requirements of specific knowledge for pediatric sleep
medicine. In this study, sleep laboratory was set up for recording
polysomnography, a gold standard of sleep recording, for research
purpose. Then polysomnography was performed for 44 children
from 6 to 15 years old. Analyzing cortical electroencephalographic
activity and heart rate variability in relation to jaw muscle activity,
we found that tooth grinding occurred in cluster in the light NREM
sleep during the transition from deep NREM sleep to REM sleep.
This period was characterized by the decrease of delta EEG power, the raise in sympathetic activity and the increase of arousal
events. Therefore, the study first documented in children that theoccurrence of tooth grinding is cyclically fluctuated in relation tosleep cycles.

▍ Significance of the research and Future perspective
The results provide a new insight of pediatric sleep bruxism forthe future development of diagnosis and treatment strategies.

P a t e n t
Tr e a t i s e

Shiraishi, Y; Tachibana, M; Shirota, A et al. Relationships between cortical, cardiac, and arousal-motor activities in the genesis of rhythmic masticatory
muscle activity across sleep cycles in primary sleep bruxism children. Sleep. 2021; 44(11): zsab156. doi: 10.1093/sleep/zsab156

URL
K e y w o r d sleep, bruxism, development, children, EEG