Dental Scaling Within the Previous Year and Depressive Symptoms Among Korean Adults: A Nationwide Cross-Sectional Study

Background and Objectives: Dental scaling may be associated with mental health, but whether this reflects dental care itself or broader healthcare engagement is unclear. We examined the association between dental scaling within the previous year and depressive symptoms among Korean adults and its attenuation after sequential adjustment. Materials and Methods: We analyzed 231,410 adults aged ≥ 19 years from the 2024 Korea Community Health Survey. Scaling was self-reported; depressive symptoms were defined as a Patient Health Questionnaire-9 score ≥ 10. Survey-weighted logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs). Model 2 was the primary confounder-adjusted model, whereas Model 3 (exploratory attenuation model) was additionally adjusted for oral health, healthcare access, and general health. Sensitivity analyses included an alternative PHQ-9 threshold, expanded covariate models, multiple imputation, E-values, and restricted cubic splines. Results: Depressive symptoms were less prevalent among participants reporting scaling than those not reporting scaling (3.2% vs. 5.3%). The crude OR was 0.58 (95% CI: 0.55–0.61); the Model 2 OR was 0.74 (95% CI: 0.70–0.78) and was attenuated to 0.88 (95% CI: 0.83–0.93) in Model 3. Expanded models and multiple imputation yielded similar estimates. The Model 3 E-value was 1.54 (confidence-limit E-value: 1.36). With flexible modeling of age and sleep duration, the Model 3 OR was 0.93 (95% CI: 0.87–0.98). Conclusions: Self-reported scaling within the previous year was inversely associated with PHQ-9-defined depressive symptoms, with attenuation after additional adjustment and flexible modeling. The cross-sectional design precludes causal inference, and these findings do not establish that scaling prevents or treats depressive disorders.