Teeth and physical fitness in a community-dwelling 40 to 79-year-old Japanese population

Decline in the number of teeth and physical fitness begins from 40 years of age; however, several epidemiological studies have identified relationships between oral conditions and physical performance parameters in community-dwelling elderly population. The aim of this study was to validate the relationship between the muscle mass and its function and oral conditions (number of teeth and dental occlusion) after 40 years of age in a community-dwelling population in Japan. The subjects comprised of 552 volunteers (198 males and 354 females, 40-79 years) who participated in the Iwaki Health Promotion Project in 2013. Multiple linear regression analyses were performed with the measures of the muscle mass and its function as objective variables and the measures of the number of teeth, age, body mass index, medical history, serum albumin concentration, smoking status, habitual alcohol intake, marital status, education levels, and exercising habits as explanatory variables. The relationships between the Eichner index and the muscle mass and its function were analyzed using analysis of covariance, with adjustment for confounding factors. After adjusting for confounding factors, the number of teeth was shown to be an independent risk factor for the timed 10 m walk test (in females) and the skeletal muscle mass of the whole body (in males). The results also revealed that the timed 10 m walk test was significantly correlated with the Eichner index (Classes A and C in females were correlated). This cross-sectional study on a Japanese community-dwelling population revealed relationships between oral conditions and the muscle mass and its function. However, the interpretation of our results was hampered by a lack of data, including those on socioeconomic status and longitudinal observations. Future research exploring teeth loss and the muscle mass and its function is warranted.