Factors correlated to oral frailty and number of remaining teeth among 80-year-old population in Japan.

Background: 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. Additionally, the participants with ≥ 20 remaining teeth are associated with a lower risk of cognitive frailty in older adults. Herein, we aimed to examine the correlations between the high risk of oral frailty and oral conditions or health behavior in community-dwelling 80-year-old adults in Japan. Additionally, our secondary aim was to investigate the factors associated with ≥ 20 remaining teeth.

Methods: The present investigation was designed as a cross-sectional study using data from an adult dental health field study. This study included participants only aged 80 years in Japan. Oral frailty was evaluated using the Oral Frailty Index-8, and ≥ 4 points were defined as high risk. Oral examination was performed, and data on oral health behavior and frailty were also collected by using a self-administered questionnaire. The logistic regression analysis was conducted, with the objective variable being the risk of oral frailty groups or remaining teeth.

Results: Overall,  3,222 participants ( 1,911 female and  1,311 men) were included. Among the participants,  1,217 (37.8%) had a high risk of oral frailty. The risk of oral frailty was significantly affected by smoking status, number of remaining teeth, dental plaque, oral malodor, family dental clinic, oral concerns, osteoporosis, and shrinking body weight. Logistic regression analysis revealed that a high risk of oral frailty was significantly associated with < 20 remaining teeth and poor oral behaviors. Additionally,  1,926(59.8%) participants had ≥ 20 remaining teeth. The participants with remaining teeth ≥ 20 were significantly affected by sex, smoking status, residential district, periodontal pocket, bleeding on probing, dental plaque,  and interdental cleaning. The participants with ≥ 20 remaining teeth were significantly associated with the residential district,  and interdental cleaning.

Conclusions: 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.