Multicenter Sleep Bruxism Clinical Registry in Japan: Development of the registry and exploratory analysis of data-driven clinical subgroups

PURPOSE: Sleep bruxism (SB) presents diverse clinical manifestations; however, phenotypic classification is limited by a lack of large-scale standardized data. We established a multicenter clinical registry for SB in Japan and explored SB subgroups using the explanatory latent class analysis (LCA). METHODS: We established a multicenter Sleep Bruxism Clinical Registry in seven dental schools across Japan. The registry enrolls adults (≥18 years) who underwent standardized electromyography (EMG) recordings of masticatory muscle activity during sleep, including both dental patients and healthy volunteers. In addition, clinical characteristics related to orofacial conditions, psychosocial factors, and sleep-related symptoms were registered for the enrolled individuals. Participants with EMG-confirmed SB were included in the exploratory LCA to identify the data-driven subgroups. RESULTS: In total, 910 individuals, including 524 SB-positive cases, were registered. The LCA identified four SB subgroups: younger individuals with few signs and symptoms (subgroup I, 35.3%), middle-aged women with frequent morning symptoms and high self-awareness (subgroup II, 16.2%), middle-aged individuals with marked tooth wear but low grinding-sound reports and self-awareness (subgroup III, 22.3%), and younger individuals with frequent signs and symptoms (subgroup IV, 26.2%). Individuals in subgroups II and IV exhibited significantly more tonic episodes than those in subgroup I, whereas those in subgroup IV exhibited more phasic episodes than subgroups I and II. CONCLUSIONS: A novel multicenter Sleep Bruxism Clinical Registry was successfully established to enable the collection of comprehensive clinical and physiological data. Exploratory LCA revealed four clinical SB subgroups with distinct EMG episode patterns, suggesting an underlying heterogeneity in SB pathophysiology.