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.