Point-of-Care Salivary Screening Adoption and Dental Caries Risk Reclassification in Rwandan Dental Hygiene Clinics: A Difference-in-Differences Analysis of Risk-Triage Thresholds

Rwandan dental hygiene clinics have begun adopting point-of-care salivary screening as an adjunct to conventional caries risk assessment, yet the consequences for risk-triage thresholds remain unexamined. The indicator, which serves here as a benchmark for cross-national measurement heterogeneity in a related preventive-service domain, had a mean of 91.964 (SD 12.468), ranging from 60.90 in Malawi to 99.70 in Kenya. The analysis specifies the reclassification estimand, distinguishes threshold-crossing from true risk change, and derives the conditions under which salivary screening adoption produces net triage improvement rather than artefactual category migration. The framework proposes that clinic-level adoption effects are identifiable only when the pre-adoption risk distribution and the screening-conditional reclassification matrix are jointly observed, and it identifies the boundary conditions under which difference-in-differences estimates of reclassification become uninformative. The contribution is a transferable estimation strategy for evaluating adjunctive screening technologies in resource-constrained dental hygiene settings, together with an explicit statement of the data requirements that Rwandan clinic networks would need to satisfy before adoption effects can be credibly estimated.