Associations between mental and oral health in Spain: a cross-sectional study of more than 23,000 people aged 15 years and over

Background: This study aimed to investigate associations between mental health and several parameters of oral health, controlling for a variety of important covariates, in a large representative sample of Spanish people. Methods: Data from the Spanish National Health Survey 2017 were analysed. Mental (i.e., depression, chronic anxiety, other psychiatric disorders) and oral health (i.e., dental caries, dental extraction, dental filling, gingival bleeding, tooth movement, dental material, missing tooth) were evaluated. Control variables included sex, age, marital status, education, smoking, alcohol consumption, and physical multimorbidity. Associations between psychiatric conditions (independent variables) and the number of poor oral health outcomes (dependent variable) were assessed using Poisson regression models. The associations were investigated in the overall population, in married participants and in those who were single/widowed/divorced/separated. Results: There were 23,089 participants [54.1% women; mean (standard deviation) age 53.4 (18.9) years]. The prevalence of at least one psychiatric condition was 15.4% in the overall sample, while the mean (standard deviation) number of poor oral health outcomes was 2.9 (1.4). There was a positive association between any psychiatric condition and the number of poor oral health outcomes [incidence rate ratio (IRR)=1.10; 95% confidence interval: 1.07-1.12], and there was a significant interaction between any psychiatric condition and marital status. The association was stronger in those participants who were single/widowed/divorced/separated. Limitations: Cross-sectional study. Oral and mental health were assessed with Yes/No questions. Exposure, outcome and covariates were self-reported. Conclusions: Those with poor mental health have worse oral health but being married has some protective benefits