Routine oral health practices and all-cause mortality among older Japanese adults: A 6-year cohort study

OBJECTIVES: To examine whether multiple routine oral health practices reduce all-cause mortality, and how these associations are modified by sociodemographic, behavioral, and health related factors. METHODS: Data were derived from the Japan Gerontological Evaluation Study (JAGES), with participants enrolled between 3 October and 14 November 2016. Participants who were not certified for long-term care insurance and completed the questionnaire version including oral health practice items were eligible; edentulous or not functionally independent individuals were excluded. Participants were categorized according to engagement in seven routine practices: toothbrushing ≥twice/day, use of interdental cleaner, tongue cleaner, toothpaste, mouthwash, and dental visits for treatment or checkups in the past 12 months. The outcome was all-cause mortality through 20 June 2023. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using inverse probability weighted Cox proportional hazard models, adjusting for confounding. For oral health practices exhibiting significant association, moderator wide analyses were conducted to explore potential effect modification by age, sex, education, income, smoking, alcohol consumption, body mass index, walking time, living status, self-rated health, number of teeth, and depression. RESULTS: During the 6-year follow-up, the mortality incidence rate was 17.3/1000 person-year among 9676 participants (46.5% male; mean age=73.7 ± 5.9 years). Significant risk reductions in all-cause mortality were observed for interdental cleaner use (HR=0.89; 95% CI=0.80-0.99) and tongue cleaner use (HR=0.77; 95%CI=0.68-0.87). No significant effect modification was detected. CONCLUSIONS: In this nationwide cohort study, the use of interdental and tongue cleaners was associated with lower all-cause mortality among community-dwelling Japanese older adults during 6 years of follow-up. CLINICAL SIGNIFICANCE: The results suggest that simple and low-cost practices may contribute to healthy longevity in ageing societies, and support further investigation into potential mechanisms, including pathways related to aspiration and respiratory infections.