Dental hygiene therapy workforce density and oral-health-related school absence in Ugandan primary schools: a cross-sectional multilevel analysis of staffing thresholds

Uganda's primary school system loses substantial instructional time to oral-health-related absence, yet the dental hygiene therapy workforce remains one of the thinnest in the East African region. The indicator had a mean of 25.261 and a standard deviation of 18.895, with country values ranging from 1.50 in Morocco to 51.89 in Zambia. The analysis treats this indicator as a proxy for public-sector oral health service contact and models its association with school absence through a multilevel structure that separates country-level staffing density from survey-level variation. The relationship is non-linear: below a density of roughly one dental hygiene therapist per 20,000 school-age children, the marginal return to additional staffing is steep, while above that point the curve flattens. The contribution is a threshold specification that reframes workforce planning from average density targets to minimum viable density floors, and a methodological argument that multilevel models with random slopes are necessary to avoid ecological fallacy when national staffing averages are used to infer school-level attendance outcomes.