Effectiveness of fluoride varnish in preventing early childhood caries in rural areas without access to fluoridated drinking water: A randomized control trial

Objectives: Early childhood caries (ECC) constitutes a serious public health issue, especially in communities without water fluoridation. We assessed the effectiveness of biannual fluoride varnish applications to prevent ECC in children from nonfluoridated rural areas. Methods: A triple-blind randomized control trial with two parallel arms was conducted with 275 two-to three-year-old children without cavitated carious lesions from 28 rural public preschools in Chile. The preschools were located in areas of low socioeconomic status without access to fluoridated water. An oral health education component was administered to children, parents and educators. A new toothbrush and toothpaste for each child was delivered to the parents at baseline and at four follow-up visits. The participants were randomly allocated to receive fluoride varnish or placebo applications every six months. Trained, calibrated dentists blind to the treatment arm performed visual dental assessments at 6, 12, 18 and 24 months. The primary endpoint was the development of cavitated carious lesions in children during the 24-month follow-up period using WHO criteria, and the secondary outcomes were an increase in caries measured as a change in the index of decayed, missing or filled teeth (dmft) since the beginning of the study and the development of adverse effects. An intention-to-treat (ITT) approach was used for the primary analysis. Results: We included 131 participants in the intervention group and 144 participants in the placebo group; of these children, 89 (67.9%) in the intervention group and 100 (69.4%) in the control group completed the protocol. The comparative ITT analysis of caries incidence after 24 months of follow-up showed a between-group prevention fraction of 18.9% (-2.9%-36.2%). Caries incidence was 45.0% for the experiment group and 55.6% for the control group (P = .081), with a mean dmft of 1.6 (SD = 2.4) and 2.1 (SD = 2.5), respectively. No adverse effects were reported. Conclusions: In conclusion, biannual fluoride varnish application is not effective in preschool children from rural nonfluoridated communities at a high risk of caries.