Oral Structural and Functional Impairment in Relation to Depressive Outcomes in Older Adults: A Systematic Review and Meta-Analysis of Observational Studies.

BACKGROUND/OBJECTIVES: Oral structural and functional impairment and depressive outcomes frequently coexist in older adults, but the strength and interpretation of their association remain uncertain. This systematic review and meta-analysis evaluated whether poorer oral status or function is associated with depressive outcomes in older populations. METHODS: Six databases were searched for observational studies published from 1 January 2016 to 5 January 2026, with an update on 19 April 2026. Eligible studies examined oral impairment as the exposure and depressive outcomes as the endpoint in older adults. Risk of bias was assessed using Newcastle-Ottawa criteria and certainty using GRADE. Comparable adjusted odds ratios (ORs) were pooled using random-effects meta-analysis with restricted maximum likelihood and Hartung-Knapp adjustment; non-comparable metrics were synthesized separately. RESULTS: Thirty studies were included; fifteen contributed to the primary OR meta-analysis. In the primary model, poorer oral status or function was associated with higher odds of adverse depressive outcomes (OR = 1.61, 95% CI: 1.31-1.99), although between-study heterogeneity was substantial (I2 = 88.1%). In the trim-and-fill sensitivity analysis, the pooled estimate decreased to OR = 1.29 (95% CI: 0.99-1.69; p = 0.0584) and no longer reached conventional statistical significance. The certainty of the primary evidence was very low. CONCLUSIONS: Poorer oral structural or functional status is associated with worse depressive outcomes in older adults, but the magnitude is heterogeneous and sensitive to small-study-effect assumptions. The evidence remains observational and of very low certainty and should be interpreted as hypothesis-generating rather than causal or treatment evidence.