Effect of Fluoride Varnish in Preventing Dental Caries of First Permanent Molars: A 24-Month Cluster Randomized Controlled Trial

Background: Caries is a prevalent health problem. This study evaluated the effect of fluoride varnish in preventing dental caries of first permanent molars. Methods: The study was designed as a stratified cluster randomized controlled trial, with classes as the unit of randomization. Classes stratified by district were followed for 24 months. All eligible children of the selected classes were included for the trial. The children in the test group were biannually applied fluoride varnish. The outcomes were measured at an individual level. Results: In total, 107 classes (51 in the test group, 56 in the control group) were recruited for the trial. Of the 5397 participants, 5005 children (2385 in the test group, 2620 in the control group) completed the study. At the 24-month follow-up, the mean decayed and filled surface increment of the first permanent molars of the children in the test group was significantly lower than that of the children in the control group (0.38 versus 0.61). The caries incidence of the first permanent molars in the test group was 17.0%, while that of the control group was 23.7%, with a PF of 28.3%. Conclusions: Semi-annual application of fluoride varnish is effective in reducing the caries increments of first permanent molars.