Introduction: It was to compare the efficacy of semiannually fluoride varnish application versus pit and fissure sealant to reduce occlusal caries incidence.
Materials and methods: A randomized parallel designed study was conducted with 352 child-ren aged 6-7 years. Participants were allocated into biannual application of varnish (n=179) (NaF 5 %( Durafluor, DENTSPLY®, Latin America) or resin-based fissure sealant (n=173) (Eco Seal, Korea®) single application without previous tooth preparation. Two visual-tactile methods including WHO and Nyvad criteria were used for caries detection. The unit of analysis was tooth surface. χ2 test, t-test, Fisher exact, and multi-variable logistic regression were used for statis-tical analysis.
 Results: Proportion of caries free (DMF=0) were 79.8% and 79.1% among the sealant and var-nish groups respectively. By using Nyvad visual-tactile criteria 60.4% and 50.2% of surfaces re-mained sound in sealant and varnish groups respectively (p < 0.001). The prevented fraction of sealant to varnish by two measures was 3.46 and 20.5 respectively. Regression model showed sealant application (OR=0.34) and tooth brushing >2 times/day (OR=0.8) were protective factors while dmfs>4(OR=0.08), and snack con-sumption >2 times/day (OR=1.3) were risk fac-tors of caries incidence.
 Conclusion: The results of this study suggest that semiannual fluoride varnish application can be recommended for preventing and reducing occlusal caries in low caries risk population.