Association between dental floss use and depression: a population-based study

BMC Oral Health. 2026 Jul 8. doi: 10.1186/s12903-026-08908-0. Online ahead of print.

ABSTRACT

BACKGROUND: Depression is a common mental health disorder with complex interactions involving systemic inflammation and oral health. Poor oral hygiene has been linked to depressive symptoms, evidence on interdental cleaning, particularly dental floss use, and depression remains limited. The aim of this study is to examine the association between dental floss use and the prevalence of depression in a nationally representative U.S. adult population.

METHODS: Data from 17,250 participants from National Health and Nutrition Examination Survey (NHANES) were analyzed. Depression was assessed using the Patient Health Questionnaire-9 (PHQ-9), with scores ≥ 10 indicating depression. Dental floss use in was determined by the Oral Health Questionnaire. Logistic and linear regression models were employed to evaluate the association between flossing and depression. Sensitivity analyses included additional adjustment for oral health and oral health as an alternative exposure. Restricted cubic spline (RCS) and subgroup analyses were also conducted.

RESULTS: Of the participants, 8% were classified as having depression. Dental floss use was inversely associated with depression risk (OR = 0.954, 95% CI: 0.931-0.978). Flossing ≥ 5 times per week was linked to a lower prevalence of depression (OR = 0.735, 95% CI: 0.619-0.872). RCS analysis revealed a linear relationship between increased flossing frequency and decreased depression risk, and findings were robust across sensitivity analyses.

CONCLUSION: Regular use of dental floss was associated with a reduced risk of depression. These findings highlight the importance of interdental cleaning as a potential preventive strategy in oral hygiene habits and mental health promotion.

PMID:42415065 | DOI:10.1186/s12903-026-08908-0