Cognitive function and number of teeth in a community-dwelling population in Japan

Background: It has been reported that oral health is poor in elderly populations and is associated with poor cognition and dementia. The objective of this study was to examine the association between tooth loss and cognitive function in a community-dwelling population in Japan. Methods: We examined the association between tooth loss and cognitive function in 462 Japanese community-dwelling individuals. The Mini-Mental State Examination (MMSE) was employed to measure global cognitive status. A multiple logistic regression analysis, with both crude and adjusted conditions for confounding factors, was used to assess the relationship between poor cognition and the number of remaining teeth. Results: The overall prevalence of poor cognition (MMSE <= 23) in this study population was 5.6%. Subjects with poor cognition were significantly older, less educated, scored lower in intellectual activity, and had fewer remaining teeth than those with normal cognition. According to the multiple logistic regression analysis, a lower number of teeth (0-10) was found to be a significant independent risk factor (OR = 20.21, 95% confidence interval = 2.20 to 185.47) of cognitive impairment. Conclusions: This cross-sectional study on a Japanese community-dwelling population revealed relationships between tooth loss and cognitive function. However, the interpretation of our results was hampered by a lack of data, including socioeconomic status and longitudinal observations. Future research exploring tooth loss and cognitive function is warranted.