Analytical Study of the Effectiveness of School-Based Fluoride Varnish Programmes on Caries Incidence in North West Nigeria

School-based fluoride varnish application is one of the most evidence-supported caries prevention strategies for children, yet analytical evaluation of its effectiveness under real-world conditions in North West Nigerian schools is absent from the published literature. This study analytically evaluated the effectiveness of a school-based fluoride varnish programme on caries incidence among primary school children in Katsina State over a 24-month follow-up period. A cluster-randomised controlled design assigned 12 schools to intervention (biannual 5% sodium fluoride varnish application by trained dental therapists, n = 320 children) and 12 schools to control (no varnish, n = 318 children). DMFT was recorded at baseline, 12 months, and 24 months. Oral hygiene and dietary data were collected at each interval. Results showed a 36.4 percent reduction in new caries increment in the intervention group compared to control at 24 months (mean DMFT increment 0.62 versus 0.98, p < 0.001). The intervention effect was greatest in children with high baseline sugar consumption. No significant adverse effects of varnish application were documented. Teacher-delivered oral health education showed additive benefit when combined with varnish application. Implementation costs were calculated at N4,200 per child annually, below the estimated cost of dental treatment for untreated caries. The study provides the first evidence-based evaluation of a school fluoride varnish programme in North West Nigeria and recommends state-level policy adoption and integration with existing PHC maternal and child health programmes. Keywords: fluoride varnish, school-based caries prevention, cluster randomised controlled trial, Katsina State, caries incidence