Physiological sequences on tooth grinding under sleep-like states in animals

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K18632
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 57050:Prosthodontics-related
• Research Institution: Osaka University
• Principal Investigator: Makoto Higashiyama 大阪大学, 大学院歯学研究科, 招へい教員 (50781663)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: ブラキシズム / 脳波 / 麻酔 / 心拍数 / 呼吸数

Outline of Final Research Achievements

To elucidate the mechanism of sleep bruxism, we utilized anesthetized experimental animals that exhibited rhythmic jaw movements. We analyzed the characteristics of these jaw movements and the physiological mechanisms accompanying their occurrence. In animals administered ketamine, rhythmic jaw movements with a predominance of the jaw-opening muscles occurred as the slow-wave activity attenuated, accompanied by a gradual increase in heart rate and respiratory rate. On the other hand, under urethane administration, rhythmic jaw movements similar to bruxism with a predominance of jaw-closing muscle activity were observed, along with an increase in respiratory rate and enhanced activity in the α and γ bands of the EEG. Therefore, not only fluctuations in bran state but also changes in autonomic nervous system activity can be involved as physiological conditions for the occurrence of rhythmic jaw movements in the unconscious state induced by anesthesia.

Free Research Field

口腔生理学

Academic Significance and Societal Importance of the Research Achievements

睡眠中の歯ぎしりのメカニズムは未だ不明である。今回の実験では、麻酔を用いた実験系を用いて、睡眠様の脳波活動の変動中に生じるリズミカルな運動の発現特性について解析を行ったところ、リズミカルな顎運動の発現が、脳内全体の活動バランスのみに依存しているわけでないことが示唆された。その一方で、覚醒脳波の出現や呼吸数の増加を伴うことから、リズミカルな顎運動の発現には、脳幹を中心とした皮質下の活動亢進も重要である可能性が示唆された。したがって、睡眠時ブラキシズムの歯ぎしりをはじめとする無意識下で生じるリズミカルな顎運動の発現機序の解明に有用な知見が得られた点で学術的意義がある。