Nutrition/Obesity
Self-reported flossing frequency and odds of untreated interproximal coronal caries in US adults: evidence from NHANES 2015–2018 Edmond Appiah* Edmond Appiah Appiah Children’s Hospital of Philadelphia
Background: Interproximal dental caries remain prevalent among US adults despite overall declines in caries experience, and mechanical plaque removal via flossing is recommended for prevention. However, evidence on the specific efficacy of flossing frequency for reducing interproximal caries risk is mixed and limited, particularly regarding dose-response patterns.
Methods: We analyzed cross-sectional data from 6,959 US adults aged 30 years and older in the National Health and Nutrition Examination Survey (NHANES) 2015–2018 cycles. Untreated interproximal coronal caries were identified via clinical oral examinations. Self-reported flossing frequency was categorized as 0 days/week (reference), 1–3 days/week, or 4–7 days/week. Weighted multivariable logistic regression models estimated adjusted odds ratios (OR) and 95% confidence intervals (CI), controlling for age, sex, race/ethnicity, poverty-income ratio, education, insurance status, time since last dental visit, gum treatment history, smoking, diabetes, sugar intake tertile, and self-rated oral health. Rao-Scott chi-square tests assessed bivariate associations, and survey weights accounted for complex sampling design.
Results: Overall weighted prevalence of any untreated interproximal caries was 9.18% (95% CI: 7.55–10.81). Compared with flossing 4–7 days/week, never flossing showed higher unadjusted prevalence (11.11% vs 8.96%) and, after full adjustment, significantly lower odds of caries (OR 0.67, 95% CI: 0.48–0.94, p=0.022). Flossing 1–3 days/week showed a non-significant protective association (OR 0.72, 95% CI: 0.45–1.16, p=0.170). Bivariate differences were evident by socioeconomic factors, with higher caries prevalence among those with lower income, less education, and no recent dental visit.
Conclusions: Near-daily flossing is associated with reduced odds of untreated interproximal caries in a nationally representative sample, while occasional or no flossing confers less or no benefit after confounder adjustment. These findings support emphasizing consistent interdental cleaning in preventive oral health guidance and highlight opportunities to address disparities through targeted education and access to care.