Association between number of remaining teeth and incident depression in a rural Chilean cohort

Objectives: Previous studies have established an association between tooth loss and depression. However, longitudinal evidence is scarce and needs to be verified in other populations. The aim of this study was to examine the longitudinal association between the number of remaining teeth and incident depression at 2- and 4-years follow-up in individuals enrolled in the Maule cohort (MAUCO) in Chile.

Methods: This prospective study used the information of individuals, aged 38 to 74 years, excluding those with depression at baseline. The number of remaining teeth at baseline was determined in four groups: "20 or more teeth", "10 to 19 teeth", "1 to 9 teeth" and "no natural teeth". Depression was measured through the PHQ-9. Logistic regression was performed to calculate the odds ratios (OR) for incidence depression at both periods of follow-ups, adjusting for age, sex, educational attainment, diabetes mellitus II, and stressful events at follow-up. Also, we performed adjusted multinomial logistic models to analysis the association between the number of remaining teeth and depression severity.

Results: In total individuals (n = 3335 at follow 1, n = 2461 at follow 2), all groups have ORs for incident depression above 1 considering 20 or more teeth as reference. In men, those with 10-19 teeth have 2.44 times higher odds of incident depression than those with 20 or more teeth (OR 2.44, CI 95% 1.33-4.50). Edentulous subjects at 4 years follow-up had 2.24 times higher odds of depression than those with more than 20 teeth (OR 2.24 CI 95%1.35-3.72). In women, the ORs (CI 95%) of incident depression were 2.56 (1.50-4.39), 1.56 (1.02-2.40) and 1.27 (0.90-1.81) for "none", "1-9", "10-19" respectively in comparison to the reference group. In edentulous individuals at baseline, the odds for each of the comparisons "mild vs no", "moderate vs no", "moderately severe vs no" and "severe vs no" were above 1, at both follow-ups.

Conclusion: Individuals with less than 20 teeth in the mouth could had higher odds of incident depression at 2- and 4-years follow-up, with differences between men and women. Also, in our study, edentulism was associated with increased odds of incident depression at 4-years follow-up in women, and with higher levels of severity of depressive symptoms.