Advanced-Curative Oral-Health Entitlement, Basic Restorative Service Availability, and Untreated Dental Caries in Primary Dentition: A Cross-National Ecological Study

Background/Objectives: Formal oral-health entitlement does not necessarily imply available services or effective access. We examined whether the country-level association of basic restorative service availability with untreated caries in primary teeth among children aged 1–9 years differed by advanced-curative entitlement. Methods: Data for 2021 were harmonized from IHME, WHO, FAOSTAT, and the World Bank for 92 countries with complete data. Ordinary least squares regression with HC3-robust covariance included entitlement, reported restorative service availability, their prespecified interaction, log GDP per capita, sugar availability, and WHO region. Results: Mean untreated caries prevalence was 45.10% (SD, 7.60). The interaction was positive (β = 9.00 percentage points [pp]; 95% CI, 1.71–16.29; p = 0.016). Among countries without advanced-curative entitlement, availability was associated with lower prevalence (β = −6.62 pp; 95% CI, −12.23 to −1.02; p = 0.021). Compared with Yes/Available, the No/Available category had a 6.29 pp lower adjusted predicted prevalence (95% CI, −11.06 to −1.52; Holm-adjusted p = 0.031). The child-population-weighted interaction was not statistically significant (β = 6.11 pp; 95% CI, −1.01 to 13.24; p = 0.092). Conclusions: Entitlement and reported availability are clinically non-equivalent indicators and cannot establish policy–service alignment or effective access. Findings are ecological associations, not evidence of policy effects.