Data sources <p>A search of four databases (PubMed, EBSCOhost, Medline, and Google Scholar) identified studies for inclusion.</p> Study selection <p>Two reviewers independently selected articles for review. Studies published in English between January 2000 and June 2024 were selected. Studies that described the association of oral health and depression, and those with an oral health factor as the independent variable and depression as the dependent variable were eligible. Systematic reviews and case reports were excluded.</p> Data extraction and synthesis <p>Data was extracted from 31 eligible articles, which included both cross-sectional and prospective cohort studies, by two reviewers independently. The results of each study were narratively described; no meta-analysis was carried out due to heterogeneity between the studies. The authors reported that results were observed after controlling confounding factors. Each reviewer independently evaluated the studies’ methodological quality and validity using the Joanna Briggs Institute (JBI) tool for cross-sectional studies.</p> Results <p>There were mixed results regarding the impact of oral health on depression. Some studies reported significantly increased risk of depression with both tooth loss and oral pain, whilst others reported no association. Impaired oral function was consistently associated with symptoms of depression.</p> Conclusions <p>The review concluded that oral health has a significant impact on depression and that there is a bi-directional relationship between the two, necessitating targeted interventions to improve oral health and thus positively impact mental health.</p>