Socioeconomic inequalities in untreated root caries in adults and older adults in two national cross-sectional samples.

INTRODUCTION: Aging and tooth retention expand root caries susceptibility. This study aimed to evaluate socioeconomic inequalities in untreated root caries. METHODS: Cross-sectional data from the 2010 and 2023 Brazilian National Oral Health Surveys (SBBrasil) were analysed, including dentate adults (35-44y) and older adults (65-74y). Untreated root caries was assessed according to WHO criteria. Socioeconomic inequalities were evaluated using educational attainment, household income, household assets, and a latent socioeconomic position (SEP) indicator estimated through generalised structural equation modelling. Absolute and relative inequalities were quantified using the Slope Index of Inequality (SII) and Concentration Index (CIX), respectively. RESULTS: 28,318 dentate participants were included (13,220 in 2010 and 15,098 in 2023). Between survey years, edentulism declined from 20.2% to 11.5%. Prevalence of root caries increased from 16.0% (95%CI:14.2-17.9) in 2010 to 22.0% (95%CI:19.2-25.2) in 2023, particularly among older adults (22.4% to 26.8%). Negative SII and CIX values indicated that root caries remained concentrated among socioeconomically disadvantaged groups. Among adults, absolute inequalities widened over time, increasing from -17.6 to -21.7 p.p. according to SEP. Among older adults, SEP inequalities that were not consistently observed in 2010 became statistically significant across all indicators in 2023, reaching -23.8 percentage points (SII) and -15.4 (CIX). CONCLUSION: Untreated root caries increased in Brazil between 2010 and 2023 despite substantial gains in tooth retention. Socioeconomic inequalities persisted and intensified over time, suggesting that the ongoing epidemiological transition in oral health has expanded the population susceptible to root caries without equitable improvements across social groups.