OBJECTIVETo evaluate the clinical effect of fluoride varnish in preventing caries of primary teeth, and to compare the caries prevention effects of fluoride varnish with two different concentrations.

METHODS150 children whose ages were three year-old were randomly chosen from one of nurseries of Chongqing, and were randomly divided into four groups with 37 children in 0.5% fluoride varnish group, 38 children in 0.1% fluoride varnish group, 39 children in 0.5% sodium fluoride group and 36 children in blank group. The groups included 71 'girls and 79 boys. Protective measure was applied every half an year and the research has lasted for two years. The research was designed by double-blinded methods, and was carried out with the dental caries standard suggested by World Health Organization. All the data were collected and the clinical effects of four groups were compared.

RESULTSThe average caries index and caries surface index of 0.1% fluoride varnish group and those of control groups were significantly higher than that of 0.5% fluoride varnish group. There were no significant difference between the average caries index and caries surface index of 0.1% fluoride varnish group and those of control groups.

CONCLUSION0.5% fluoride varnish was effective in preventing caries of primary teeth.