Masticatory function and frailty: insights from NHANES and CHARLS

BACKGROUND: The association between oral health and frailty has been established. This study aimed to examine the association between masticatory function (assessed by functional tooth units (FTU) and edentulism), and frailty status with mortality risk among frail individuals. METHODS: Data from National Health and Nutrition Examination Survey (NHANES) and China Health and Retirement Longitudinal Study (CHARLS) were analyzed. Masticatory function was assessed using FTU and edentulism. Frailty was defined using a 49-item and 32-item index in NHANES and CHARLS respectively. Multivariate logistic regression and Cox proportional hazards models, and restricted cubic spline analyses were used to examine associations between mastication, frailty, and mortality. Sensitivity analyses were conducted. RESULTS: The prevalence of frailty was 29.97% and 10.66% in NHANES and CHARLS respectively. Individuals having FTU of 10-12 showed a 24% lower risk of frailty compared to those with FTU of 0-3 in NHANES, and edentulism had 88% higher risk in CHARLS. Among frail participants, higher FTU scores were linked to lower all-cause (HR = 0.73, 95% CI: 0.60-0.89) and cancer-related mortality (HR = 0.51, 95% CI: 0.33-0.80), but not cardiovascular mortality in NHANES, and edentulism had 56% higher mortality in CHARLS. The association between FTU and frailty was linear, subgroups and sensitivity analyses confirmed robustness. CONCLUSIONS: Better masticatory function, as indicated by higher FTU, is associated with lower frailty prevalence and improved survival among frail individuals, while edentulism linked to higher prevalence and mortality. These findings emphasize the importance of maintaining functional dentition and oral rehabilitation in geriatric care.