title: Comparison of cerebral activity during teeth clenching and fist clenching: a functional magnetic resonance imaging study.
abstract: Using functional magnetic resonance imaging (fMRI), we compared the cerebral activity during bilateral light fist-clenching and light-teeth clenching to provide more information on the central processing mechanisms underlying awake bruxism. Fourteen subjects participated in our study. Statistical comparisons were used to identify brain regions with significant activation in the subtraction of light fist clenching and light teeth clenching activity minus baseline. Participants also evaluated the perceived effort of clenching for each task, using a visual analogue scale of 0-100, after fMRI was performed. Bilateral light fist-clenching significantly activated the bilateral sensorimotor cortex, while light teeth-clenching was significantly associated with activation of the bilateral sensorimotor cortex, supplementary motor area, dorsolateral prefrontal cortex, and posterior parietal cortex. The VAS scores for fist clenching and teeth clenching were not significantly different. As light teeth-clenching activates a more extensive cortical network compared with light fist-clenching, we suggest that the teeth clenching may induce a more complex cerebral activity compared with the performance of a hand motor task. The clinical significance of these findings remains unknown but could perhaps be related to the propensity to trigger awake bruxism.
authors.affiliation: Department of Clinical Oral Physiology, Nihon University School of Dentistry at Matsudo, Chiba, Japan. iida.takashi96@nihon-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Iida
authors.forename: M
authors.initials: M
authors.lastname: Kato
authors.forename: O
authors.initials: O
authors.lastname: Komiyama
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Asano
authors.forename: T
authors.initials: T
authors.lastname: Kuroki
authors.forename: T
authors.initials: T
authors.lastname: Kaneda
authors.forename: P
authors.initials: P
authors.lastname: Svensson
authors.forename: M
authors.initials: M
authors.lastname: Kawara
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D001921:Brain / Q000502:physiology*; D002012:Bruxism / Q000503:physiopathology; D005260:Female; D006225:Hand / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008410:Masticatory Muscles / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology; D009048:Motor Skills / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology; D013997:Time Factors; D014070:Tooth / Q000502:physiology*