Contextual school performance, individual educational delay, income inequality and oral health among adolescents: A repeated cross-sectional study in Brazil, 2010 and 2023

Objectives: To examine the association of contextual school performance, individual educational delay, and socioeconomic conditions with untreated dental caries and tooth loss in Brazilian adolescents. Methods: Data from two nationally representative surveys (SB Brasil, 2010, n = 11,895; 2023, n = 9181 after exclusions). Outcomes were untreated caries and any tooth loss from the DMFT index. Contextual exposure was a Public School Performance Score (PSPS) derived by principal component analysis of school dropout, grade retention, and the Basic Education Development Index. Multilevel logistic models estimated odds ratios (ORs) per 1-unit SD increase in the PSPS for each survey year, adjusting for sex, age, equivalised income, educational delay, municipal income tertiles, and water fluoridation. Results: The PSPS distribution shifted rightwards between surveys (median rose from 0.99 to 2.43), reflecting improvements in IDEB and reductions in dropout and grade retention. In 2010, a 1-SD higher PSPS was associated with significantly lower odds of untreated caries (OR = 0.92, 95%CI 0.84, 0.99) and tooth loss (OR = 0.88, 95%CI 0.81, 0.97). By 2023, the associations had weakened and were no longer statistically significant: caries OR = 0.97 (95%CI 0.86, 1.10); tooth loss OR = 0.95 (95%CI 0.83, 1.08). The year-by-score and cross-level interactions were not statistically significant. Conclusion: The contextual gradient in oral health associated with school performance observed in 2010 was not detectable in 2023, despite overall improvements in educational indicators. Clinical Significance: Even when average school performance rises, additional school-based oral health strategies may be needed to maintain the health gradient, as universal improvements do not automatically translate into reduced inequalities.