A public health cluster randomised control trial of the effectiveness of fluoride varnish delivered in the school setting

The aim of this study was to measure the effectiveness of fluoride varnish in preventing caries in the permanent dentition when delivered in the school setting. The study design was a cluster randomised, two-compartment, parallel trial. A total of 2967 children aged 7-8 years, attending 190 schools were recruited into the trial. Participating schools were randomised into test and control groups using a two stage stratification approach, based on location and school size. Children in the test group received fluoride varnish containing 22,600 ppm fluoride as sodium fluoride applied, three times a year for three years to the first permanent molars. The control group received no intervention. The primary outcome measures were DFS and DFT increment, in addition the change in caries prevalence was compared and adverse reactions were also recorded. Assessment was performed by trained and calibrated examiners blind to the allocation. Over 60% of children received all 9 applications of fluordie varnish. At follow up DFS increment was 0.68 (SD 2.13) in the control group and 0.65 (SD 2.17) in the test group, there was no statistically or clinically significant difference between the groups. Only 12 adverse reactions were recorded, all of which were clinically inconsequential. In conclusion fluoride varnish can be effectively delivered in a primary school setting and adverse reactions are rare, but we could find no evidence to support use of fluoride varnish to prevent caries in first permanent molars when delivered as a public health intervention in schools in the UK.