Silver Diamine Fluoride Versus Atraumatic Restorative Treatment and Dental Caries Survival in Zambian Primary Care Clinics: A Target-Trial Emulation of Minimally Invasive Therapy Selection

Zambian primary care clinics increasingly must choose between silver diamine fluoride (SDF) and atraumatic restorative treatment (ART) for arresting cavitated dentine caries, yet the two therapies have never been compared under the cluster-level conditions in which such choices are actually made. Power was estimated across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points.54 clusters are required to detect a 5-percentage-point difference at 80% power under this variance structure, and that the minimum detectable effect falls steeply as cluster count rises from 8 to 32. The BACI interaction estimator is shown to be sensitive to the intraclass correlation, and the design is only defensible when the correlation is estimated rather than assumed. The contribution is a power and sensitivity characterisation of the BACI design for minimally invasive caries therapy selection, with implications for how Zambian primary care evaluations should be sized and reported.