Effectiveness of fluoride varnish on caries in the first molars of primary schoolchildren: a 3-year longitudinal study in Guangxi Province,China

Aims: To evaluate the effectiveness of 5% sodium fluoride varnish on caries in first permanent molars and to assess the suitability of using this method to control caries among children in rural areas of Guangxi province, China. Methods: A total of nine schools with 32 classes were selected by simple random sampling. There were 999 students in the experimental group and 1,004 in the control group. The experimental group received oral health education and topical application of 5% sodium fluoride varnish, while the control group received oral health education only. Dental examinations were performed in November 2014 and November 2017, and the modified International Caries Detection and Assessment System (ICDAS-II) was used to record the caries status of the first permanent molars. The data were entered into SPSS 22 for statistical analysis. Results: A total of 1,748 students (853 in the experimental group and 895 in the control group) completed the study. After 3 years of intervention, the experimental group had a lower prevalence of caries, a lower caries increment, a lower decayed, missing and filled teeth (DMFT) index and a lower decayed, missing and filled surfaces (DMFS) index compared with the control group (respectively: 58.9% vs 65.5%, 34.8% vs 42.1%, 1.38 vs 1.59 and 2.06 vs 2.38). All the differences were statistically significant (P < 0.05). Conclusion: In this study population, twice-yearly application of 5% sodium fluoride varnish and oral health education were more effective for preventing caries in first permanent molars than oral health education alone. The implementation of fluoride varnish application as a public health measure in schools in rural areas is recommended.Key words: Fluoride varnish, first molars, caries prevention, schoolchildren