Relationship between sleep bruxism and masticatory performance in healthy adults: A cross-sectional study

Abstract

Statement of problem: Bruxism may have positive clinical consequences, but whether it contributes to masticatory function remains unclear. Purpose: The purpose of this clinical study was to clarify the relationship between sleep bruxism and masticatory performance in young adults with healthy dentitions and to determine the roles of occlusal force, dental occlusion, temporomandibular disorders (TMDs), and jaw symptoms. Material and methods: Ninety-seven dental students with healthy dentitions participated in this cross-sectional study (median age, 21.9 years; 84 women). Sleep bruxism was assessed at the dental level as the relative peeled area of a BruxChecker worn for 3 nights. Occlusal contact area and maximum occlusal force were measured using silicone transillumination and the Innobyte system. Frequencies of bruxism-related jaw symptoms and TMD were determined using the BruxScreen and diagnostic criteria for TMD protocols. Masticatory performance was assessed by masticating bagged silicone for 20 cycles and calculating the masticatory performance index as the percentage of silicone in weight that passed a 3.15-mm sieve. Bivariate and multiple linear regression analyses were performed, followed by moderated mediation modeling that considered the relative peeled area as a predictor, masticatory performance index as an outcome, and sex as a covariate (α=.05). Results: Relative peeled area showed a bivariate positive correlation with the masticatory performance index (P<.05), but this was not significant in the stepwise multiple regression model (P>.05). Moderated mediation analysis revealed the relative peeled area exerted a positive indirect effect on masticatory performance via the occlusal force and occlusal contact area, which functioned as serial mediators. This indirect effect was not significant in participants with TMD pain and frequent jaw symptoms (P>.05). Conclusions: Sleep bruxism may enhance masticatory performance in healthy dentate adults without TMD pain or bruxism-related jaw symptoms. This effect is primarily mediated by an increase in occlusal force and an enlargement of the occlusal contact area.