Oral Health Literacy-Adapted Hygiene Counselling Dose and Dental Caries Increment Among Kenyan Primary Schoolchildren: A Target-Trial Emulation of Counselling Intensity Thresholds

School-based oral health counselling is widely promoted, yet the minimum number of sessions needed to reduce caries increment in Kenyan primary schoolchildren remains unspecified. 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.52 clusters are required to detect a 5-percentage-point effect at 80% power, and that power rises steeply with cluster count but remains below 80% for 3-percentage-point effects even at 32 clusters. The intraclass correlation of 0.64 dominates the design, making cluster-level randomisation inefficient at small cluster counts. The contribution is a pre-specified, reproducible power framework that links counselling dose thresholds to detectable caries increment, enabling Kenyan school oral health programmes to size evaluations before committing resources. The paper does not report empirical caries outcomes; it characterises the operating characteristics of the design that would estimate them.