Association of oral health literacy with oral health behaviors, perception, knowledge, and dental treatment related outcomes: a systematic review and meta-analysis

Objectives: To conduct a systematic review and meta-analysis regarding the association of oral health literacy (OHL) with oral health behaviors, perception, knowledge, and dental treatment related outcomes. Methods: Eight electronic databases were searched up until June 2017. Studies regarding the aforementioned outcomes measuring OHL through a validated instrument and in which OHL was an explanatory variable were included. Two independent reviewers selected studies, extracted data, and analyzed the risk of bias of the studies. Meta-analysis using random effect modeling was undertaken. Pooled estimates were calculated with 95 percent confidence interval (CI) and odds ratios (OR). Results: Twenty-five studies were included in the systematic review and three in the meta-analysis. Most studies were cross-sectional (n = 21) and had a high risk of bias (n = 17). The meta-analysis showed no association between OHL and frequency of visit to the dentist for adults, either through bivariate analysis (OR = 1.25; 95 percent CI: 0.95-1.63) or multivariate analysis (OR = 1.90; 95 percent CI: 0.77-4.84). Dental anxiety and night bottle-feeding were associated with low OHL (P< 0.05). Most studies regarding tooth brushing frequency found no association with OHL. Most studies regarding oral health knowledge related outcomes reported an association with higher OHL. The literature was inconclusive regarding the association between OHL and dental treatment outcomes, oral health behaviors, and oral health perception. Conclusions: The current scientific evidence suggests that no association exists between OHL and any of the outcomes investigated. Further prospective studies with a higher methodological quality are necessary to confirm the evidence.