Are the inequalities in dental caries decreasing over time in Brazil? A comparison between the urban population in two National Oral Health Surveys

OBJECTIVES: To assess changes in socioeconomic inequalities in the distribution of untreated dental caries in permanent teeth in Brazil. METHODS: Cross-sectional data from the 2010 and 2023 Brazilian National Oral Health Surveys were used. Untreated dental caries prevalence was estimated and stratified by household family income and schooling, and presented according to age groups: 12y, 15-19y, 35-44y, 65-74y. To assess inequalities, two measures were applied: the Slope Index of Inequality (SII) and the Concentration Index of Inequality (CIX). RESULTS: A total of 63,693 individuals were included (30,171 in 2010 and 33,522 in 2023). The prevalence of untreated dental caries was 44.1% (95%CI: 41.7-46.5) in 2010 and 44.8% (95%CI: 42.5-47.1) in 2023. Negative coefficients for both SII and CIX confirm a consistent socioeconomic and educational inequalities gradient, with greater disease burden among the most disadvantaged groups. Regarding household family income, a maintenance of absolute and relative inequalities from 2010 to 2023 was observed. Regarding schooling, an overall trend of maintenance of inequalities was also observed; no significant absolute inequalities were observed for 12-year-olds in 2010 or 2023, while relative inequalities were non-significant in 2010 but became significant in 2023. Sensitivity analysis excluding edentulous maintained the main findings in younger groups (12y, 15-19y, and 35-44y) and yielded significance or strengthened the effect for absolute and relative inequalities in older adults (65-74 years) for both stratifiers. CONCLUSION: The study shows non-significant changes in untreated dental caries prevalence in the 13-year interval. The socioeconomic inequalities remain stable and significant. CLINICAL SIGNIFICANCE: The persistence of socioeconomic inequalities in untreated dental caries, despite minimal change in overall prevalence, indicates that vulnerable groups remain disproportionately affected. These findings reinforce that public health policies must prioritize reducing social inequalities and addressing the social determinants of health to improve oral-health outcomes.