Association between functional tooth units and frailty in older adults: a cross-sectional study using NHANES...

Dental status, dietary intake, and frailty are closely interrelated among older adults. Nevertheless, the association between posterior occlusal support and frailty, and whether diet-related indicators can statistically account for part of this association, remain insufficiently elucidated. To primarily investigate the association between functional tooth units (FTUs) and frailty. This study used data from the NHANES 2005-2018. Weighted multivariate logistic regression models were applied to examine the associations of FTUs, overall dietary index for gut microbiota (DI-GM), and its specific components with frailty. Restricted cubic spline (RCS) analysis was performed to test the nonlinear relationship between FTUs and frailty, and further subgroup analyses were conducted. Exploratory mediation analyses were used to assess whether DI-GM and its components statistically partially explained the association between FTUs and frailty. 6,758 individuals were included, with a frailty prevalence of 18.34%. Following comprehensive covariate adjustment, higher FTUs were associated with lower odds of frailty (OR = 0.94, 95% CI: 0.91-0.96, P < 0.001). RCS analysis revealed no significant nonlinear association between FTUs and frailty (P-for-non-linearity > 0.05). Subgroup analyses showed no significant interactions between FTUs and frailty (P-interaction > 0.05). Among older adults in the United States, higher FTUs are associated with lower odds of frailty. Nevertheless, these findings only suggest interrelationships among oral status and frailty in older adults and cannot establish causal relationships.