A population-based study on the association between periodontitis, flossing behavior, and mortality

The benefits of regular dental flossing for oral hygiene are well-established. However, it remains unclear whether flossing confers additional advantages for overall health improvement. This study examined the association of flossing frequency with all-cause mortality, characterized the dose-response relationship between flossing frequency and mortality risk, and evaluated joint associations of periodontitis and flossing behavior with mortality.

This study analyzed 10,609 participants from the U.S. National Health and Nutrition Examination Survey 2009-2014 with documented periodontitis status and flossing behavior. Inverse probability of treatment weighting and Cox proportional hazards regression collectively served for estimating hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality through December 31, 2019. To characterize the dose-response relationship, a restricted cubic spline model was fitted within the weighted Cox framework.

Any flossing was associated with 29.6% lower mortality risk (HR = 0.704, 95% CI: 0.583-0.849, P < 0.001). Restricted cubic spline analysis revealed an inverse dose-response association between flossing frequency and mortality risk, with HR declining to 0.675 (95% CI: 0.674-0.676, P < 0.001) for daily flossing. Relative to individuals with healthy periodontium without flossing, those with periodontitis without flossing had the highest mortality risk (HR=3.508, 95% CI: 2.475-4.971, P < 0.001), whereas those with periodontitis who flossed exhibited an attenuated hazard (HR=2.329, 95% CI: 1.676-3.236, P < 0.001).

An inverse dose-response association was confirmed between flossing and all-cause mortality. This association was also observed among participants with periodontitis. Because flossing was self-reported at a single time point and residual confounding remains likely, these findings should be interpreted as hypothesis generating rather than causal.

Regular flossing was associated with lower all cause mortality, including among people with periodontitis. Clinically, this reinforces flossing as a simple, low cost preventive habit. However, the findings are observational and should not be interpreted as proof that flossing directly reduces mortality.