Tooth loss and depression in Chilean participants of the National Health Survey 2016–2017: Oral and social functions mediation analysis

Background: Previous studies have indicated the association between poor oral health and depression in adults. This study evaluated oral and social functions contribution to the association between tooth loss and depressive symptoms in Chilean individuals. Methods: We used data from the Chilean National Health Survey. The number of remaining teeth (≤19 versus ≥20 teeth) and anterior tooth losses were the exposure variables. Outcome was depression, measured through a self-report question and with the Composite International Diagnostic Interview – Short Form (CIDI SF). Mediating variables were determined by five questions, including problems regarding “speaking”, “pain and suffering”, “eating”, “daily activities”, and “social relationships”. We performed logistic regression models adjusted by multiple confounders variables. Finally, we calculated indirect, direct effect, total effect, and the proportion mediated (PM). Results: We included 5383 participants. The self-reported depression and suspected depression prevalence were 22,1 % and 14,0 % respectively. The total effect of fewer remaining teeth (≤19) on self-reported depression was 1.21 (95 % CI 1.02–1.44), and 1.09 (95 % CI 0.90–1.33) for suspected depression. All five variables of oral and social functions significantly mediated the association between tooth loss and depression. Feeling uncomfortable when speaking or eating discomfort were the most significant mediators. Limitations: The mediation analysis should be interpreted with caution due to the cross-sectional design. Conclusions: Deterioration of oral and social functions was a significant mediator in the association between tooth loss and depression, in particular feeling uncomfortable when speaking or eating. This mechanism should be considered in interventions to improve mental health.