Income Inequalities and Dental Caries in 12-Year-Olds: An Ecological Comparison Between a High- and a Lower-Middle-Income Country

Background/Objectives: This study aimed to assess whether income was associated with dental caries experience and dental care levels among 12-year-old children in two contrasting economic contexts, Sri Lanka (lower-middle-income) and Wales (high-income), regardless of national income status. Methods: An ecological study design was used with published data. For Sri Lanka, the income parameters used included household income, mean per capita income, and the Gini coefficient. For Wales, the Welsh Index of Multiple Deprivation was used. Dental caries was assessed using the DMFT index and its components (DT, MT, FT), while dental care was assessed using the care index, restorative index, and treatment index. Pearson correlations were used to explore associations between income measures and both caries experience and dental care indices across districts in Sri Lanka and unitary authorities in Wales. Results: The mean DMFT for 12-year-old children was 0.6 in both Sri Lanka and Wales, with caries prevalence of 30.4% and 29.6%, respectively. In Sri Lanka, both mean household income and per capita income showed moderate, statistically significant positive correlations with DMFT (r = 0.47, p = 0.01). Income inequality, measured by the Gini coefficient, was positively associated with caries experience (r = 0.42, p = 0.03). In Wales, higher deprivation (lower income) was moderately associated with increased DMFT, in areas within the 20% (r = 0.54, p < 0.01), 30% (r = 0.53, p < 0.01), and 50% (r = 0.61, p < 0.01) deprived quintiles. The dental care indices showed no clear association with income in either of the countries. Conclusions: Income-related disparities in dental caries were evident in both countries. Prevention strategies should focus on higher-income groups in Sri Lanka and on deprived populations in Wales. However, as this was an ecological study, the results are subject to ecological fallacy and should therefore be interpreted with caution.