Dental prosthesis use and subsequent functional capacity decline among older adults: a three-year cohort study based on self-reported measures from the JAGES

Background: Functional capacity (FC) is a key determinant of healthy aging. Oral health deterioration, particularly tooth loss, has been associated with FC decline among older adults. Although dental prostheses may mitigate functional deterioration by restoring oral function, longitudinal evidence on their protective effects on FC, especially across specific domains, remains limited. This study investigated the association between dental prosthesis use and the decline in overall and domain-specific FC among older Japanese adults experiencing tooth loss. Methods: We conducted a 3-year prospective cohort study using data from the Japan Gerontological Evaluation Study (JAGES). Participants were living independently older adults aged ≥65 years with <20 teeth at baseline (2016), followed up in 2019. Dental prosthesis use (removable dentures, fixed prostheses, and/or implants) was assessed by self-report at baseline and dichotomized as use vs. non-use. FC was measured using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC), including total score and subdomains: instrumental activities of daily living (IADL), intellectual activity, and social role. FC decline was defined as a decrease of ≥1 point in the TMIG-IC score during follow-up. Modified Poisson regression with robust variance was used to estimate the relative risks (RRs) and 95% confidence intervals (CIs), adjusting for sociodemographic factors, health behaviors, comorbidities, and number of remaining teeth. Results: Among 22,632 eligible participants (mean age at baseline: 74.0 years, SD = 5.7; 51.4% male), 7,573 participants (33.5%) experienced a decline in total FC. Dental prosthesis use was significantly associated with a lower risk of decline in the total TMIG-IC score [RR = 0.91 (95% CI: 0.86-0.97)] compared with no use. For the TMIG-IC subdomain, we observed a significant association between dental prosthesis use and a lower risk of decline in intellectual activity [RR = 0.87 (95% CI: 0.80-0.96)]. Conclusions: This large-scale cohort study demonstrated that the use of dental prostheses was associated with a reduced risk of FC decline in older adults, particularly in the intellectual activity domain. Because prosthesis use and FC were assessed by self-reported and residual confounding may remain, further studies are warranted to clarify the potential role of prosthodontic rehabilitation in maintaining FC in later life.