Impact of oral self-care on incident functional disability in elderly Japanese: the Ohsaki Cohort 2006 study

OBJECTIVES To assess whether oral self-care (tooth brushing, regular dental visits and use of dentures) affects incident functional disability in elderly individuals with tooth loss. DESIGN A 5.7-year prospective cohort study. SETTING Ohsaki City, Japan. PARTICIPANTS 12 370 community-dwelling individuals aged 65 years and older. PRIMARY OUTCOME MEASURES Incident functional disability (new long-term care insurance certification). RESULTS The 5.7-year incidence rate of disability was 18.8%. In comparison with participants who had ≥20 teeth, the HRs (95% CIs) for incident functional disability among participants who had 10-19 and 0-9 teeth were 1.15 (1.01-1.30) and 1.20 (1.07-1.34), respectively (p trend<0.05). However, the corresponding values for those who brushed their teeth ≥2 times per day were not significantly higher in the '10-19 teeth' and '0-9 teeth' groups (HRs (95% CI) 1.05 (0.91-1.21) for participants with 10-19 teeth, and 1.09 (0.96-1.23) for participants with 0-9 teeth), although HRs for those who brushed their teeth <2 times per day were significantly higher (HRs (95% CI) 1.32 (1.12-1.55) for participants with 10-19 teeth, and 1.33 (1.17-1.51) for participants with 0-9 teeth). Such a negating association was not observed for other forms of oral self-care. CONCLUSIONS Tooth brushing may partially negate the increased risk of incident functional disability associated with having fewer remaining teeth.