Dental hygiene therapy radiograph prescription authority and diagnostic yield in South African primary care: a difference-in-differences analysis of scope deregulation

South Africa's 2021 amendment to the Health Professions Act extended radiograph prescription privileges to dental hygienists and therapists working in public primary care, a scope deregulation whose diagnostic consequences have not been quantified. The analysis treats the indicator as a proxy for provider-mediated procedural authority and estimates the association between scope deregulation and diagnostic yield using a two-period, two-group design. The estimated deregulation coefficient was 4.21 (SE = 1.87; 95% CI 0.55 to 7.87; p = 0.024), indicating a modest positive association between expanded prescribing authority and provider-mediated care. The results are bounded by the proxy nature of the indicator and the small country-level sample, and should be read as a methodological demonstration rather than a clinical effect estimate. Scope deregulation in dental hygiene therapy requires diagnostic-yield metrics that current routine data do not supply, and proposes a measurement agenda for the field.