Two decades of socioeconomic inequalities in the prevalence of untreated dental caries in early childhood: Results from three birth cohorts in southern Brazil.

Objectives: To estimate the socioeconomic disparities in untreated dental caries in early childhood according to socioeconomic characteristics in three birth cohorts in Southern Brazil.
Methods: The socioeconomic data to this study were collected at the 48-month follow-up and oral health studies of 1993, 2004 and 2015 Pelotas birth cohort studies. The outcome was untreated dental caries in children aged 6 (1993 cohort), 5 (2004 cohort) and 4 years (2015 cohort), dichotomized into absence/presence. Analyses were stratified by maternal skin colour/race, maternal education and family income. For statistical purposes, the prevalence difference, relative risk and absolute and relative indices of health inequality (Slope Index of Inequality-SII and Concentration Index-CIX) were used.
Results: The prevalence of untreated dental caries in primary dentition was 63.4%, 45.5% and 15.6%, in 1993, 2004 and 2015 cohorts, respectively. The prevalence of untreated dental caries was concentrated in the poorest quintile and lower maternal education group in both absolute (SII) and relative (CIX) measures of inequality, being characterized as a pro-poor event. A higher risk of untreated caries was found in the poorest quintile of family income compared with the richest quintile in the 1993 cohort (RR 1.44 [95% CI 1.05; 1.98]). That risk was higher considering the 2004 Cohort (RR 1.78 [95% CI 1.42; 2.23]) and 2015 cohort (RR 4.20 [95% CI 2.97; 5.94]) data.
Conclusions: Over the course of two decades, a higher prevalence of untreated dental caries is concentrated among the most socioeconomically deprived children.
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