Correlation between number of remaining teeth, oral health behavior, and oral frailty among 80-year-old population in Japan

Abstract Oral frailty is proposed as a new concept defined as an age-related gradual loss of oral functions accompanied by a decline in cognitive and physical functions in older adults. Herein, we aimed to examine the correlations between the high risk of oral frailty, the remaining number of teeth, and oral health behavior in community-dwelling 80-year-old adults in Japan. Oral frailty was evaluated using the Oral Frailty Index-8, and ≥ 4 points were defined as high risk. Overall, 3,389 participants (2,009 women and 1,380 men) were included. Among the participants, 1,283 (37.9%) had a high risk of oral frailty. Logistic regression analysis revealed that a high risk of oral frailty was significantly associated with < 20 remaining teeth and poor oral behaviors. Additionally, 2,006 (59.2%) participants had ≥ 20 remaining teeth. The participants with ≥ 20 remaining teeth were significantly associated with the residential district, interdental cleaning, and dementia. The main clinical implication of this study is that improving behaviors regarding oral healthcare among community-dwelling individuals may be an effective way to reduce oral frailty. Moreover, ≥ 20 remaining teeth in the 80-year-old population were notably higher in the rural areas than that in the urban areas in Japan.