Association between number of functional teeth and physical function among community-dwelling older adults: Korean Frailty and Aging Cohort Study

Background: Functional teeth are important for maintaining appropriate masticatory function and nutritional intake, affecting physical function in older adults. This study aimed to evaluate the association between number of functional teeth and physical function in community-dwelling older Korean adults.

Methods: This cross-sectional study was conducted among a total of 2,527 participants (mean age, 76.5 ± 3.9; 53.4% women) who were enrolled in the Korean Frailty and Aging Cohort Study (2016-2017). Participants were categorized based on the number of functional teeth into two groups: < 20 and ≥ 20 functional teeth. Functional teeth were defined as the remaining natural teeth with visible crowns, with or without restorations, prosthetic pontics, or dental implants on panoramic radiography. Physical function was assessed using handgrip strength, gait speed, five-times sit-to-stand test (5TSTS) duration, and the Short Physical Performance Battery (SPPB) score. Multivariate linear and logistic regression models were used to evaluate the association between number of functional teeth and physical function.

Results: Of all the participants, 869 (34.3%) had < 20 functional teeth. After full adjustment for sociodemographic factors, lifestyle, health condition, and oral health, an increase in one functional tooth was associated with a corresponding increase in gait speed (men: B = 0.002, p = 0.032; women: B = 0.002, p = 0.013) and SPPB (men: B = 0.019, p < 0.001; women: B = 0.018, p < 0.001) in both men and women. The time taken for the 5TSTS was shorter for an increase in one more functional tooth (men, B=-0.033, p = 0.006; women, B=-0.036, p = 0.021) in both men and women. An increase in one functional tooth was associated with a corresponding increase in handgrip strength only in men (men, B = 0.049, p = 0.009; women, B=-0.003, p = 0.814). The associations between < 20 functional teeth and low handgrip strength [odds ratio (OR) = 1.46, 95% confidence interval (CI): 1.03-2.06], long 5TSTS duration (OR = 1.47, 95% CI: 1.07-2.02), and low SPPB scores (OR = 1.64, 95% CI: 1.07-2.53) were significant in fully adjusted model compared with ≥ 20 functional teeth only in men.

Conclusions: Fewer functional teeth were associated with low physical function in older adults. Our results emphasize the importance of maintaining adequate functional teeth to preserve physical function in community-dwelling older adults.