Dental hygiene therapy–led caries arrest audits and fluoride varnish allocation in Malawian health centres: a regression-discontinuity analysis of supervisory review thresholds

Supervisory review thresholds are the administrative mechanism through which dental hygiene therapists in Malawi's district health centres gain authority to allocate fluoride varnish for caries arrest. the present analysis examines whether the threshold that triggers supervisory review produces a discontinuity in varnish allocation and in caries-arrest audit outcomes, using a regression-discontinuity design applied to the DHS Program indicator 'Current users most recent supply or information from a government health center' (FP_SRCM_W_GHC) across 36 African countries and 150 country-survey observations from 1990 to 2025. 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 the threshold as a running variable and estimates the jump in allocation at the cut-point. The review threshold is not a neutral administrative device but a rationing instrument whose discontinuity concentrates varnish on the side of the threshold where audit documentation is most complete, and that this concentration is a plausible mechanism for the observed cross-country dispersion. The contribution is a methodological reframing of caries-arrest audit data as a threshold phenomenon rather than a continuous coverage problem, with implications for how dental hygiene therapy-led programmes in low-resource health systems should set and monitor supervisory review cut-points.