Effects of dental prostheses and occlusal force on adverse health outcomes in community-dwelling older adults lacking functional dentition: The Longitudinal Study of the Tsurugaya Project.

OBJECTIVE: In this study, we aimed to examine the longitudinal association between combination of remaining natural teeth (RNT) and functional teeth (FT) or occlusal force (OF), with functional disability and mortality among community-dwelling Japanese adults aged >/=70 years with less than 20 remaining teeth. METHODS: The participants included 916 community-dwelling Japanese adults aged 70 years or older in 2003. Exposures were defined as a combination of RNT and either FT or OF. Outcomes included the incidence of functional disability, determined by the first certification under Japan's long-term care insurance system based on physical and cognitive status, and mortality. The participants were followed up until June 2020. Covariates included age; sex; education; comorbidity; smoking; drinking; physical and cognitive status; and depressive symptoms. Cox proportional hazard models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for functional disability and death. RESULTS: We observed a higher incidence of death among participants with <20 RNT and fewer FT (<28) than those with functional dentition (HR: 1.62; 95% CI: 1.19-2.21). The HR for death increased as the oral health category based on RNT and FT worsened (p for trend = 0.003). We observed a higher incidence of functional disability (HR: 1.25; 95% CI: 1.02-1.53) and death (HR: 1.30; 95% CI: 1.01-1.68) among those participants with <20 RNT and reduced OF (<200 N) than those with >/=20 RNT. The HR for functional disability (p for trend = 0.029) and death (p for trend = 0.042) increased as the category based on RNT and OF worsened. CONCLUSION: This prospective cohort study demonstrated that a combination of <20 RNT and fewer FT was associated with a higher mortality, whereas a combination of <20 RNT and reduced OF was associated with higher incidence of functional disability and death. Dental prostheses and maintaining OF might play an important role in preserving functionality and promoting survival among older adults with less than 20 remaining teeth.