Effect of Combined Application of Er,Cr:YSGG and Sodium Fluo-ride Varnish in Prevention of Demineralization of Primary Tooth Enamel: an In Vitro Study

Background and Aim: Previous studies revealed improved enamel caries resistance after laser irradiation. Present in vitro study evaluated the effect of Er,Cr:YSGG laser with or without topical fluoride application on microhardness of primary enamel after artificial demineralization. Materials and Methods: In this in vitro study, 35 primary molars with sound surfaces were bisected and randomly divided into seven groups of 10 specimens. In group F, 5% sodium fluoride varnish was applied while in group L1 and L2, Er,Cr:YSGG laser with the energy level of 0.25 W and 0.5 W was used, respectively. In group F/L1 and F/L2, application of fluoride varnish was followed by utilizing the Er,Cr:YSGG laser with the energy level of 0.25 W and 0.5 W respectively. Whereas, in groups L1/F and L2/F, the order of fluoride varnish and laser was reversed. After treatment, specimens were kept in distilled water for 24 h followed by a pH-cycling. Microhardness of each specimen was measured before treatment and after pH-cycling. The Analysis of Covariance (ANCOVA) was used for statistical analysis. Results: The impact of different treatments on the microhardness value was not significant among the tested groups (P=0.89). Conclusion: Our findings revealed that combination of Er,Cr:YSGG laser irradiation and application of topical fluoride have no superiority over either laser irradiation or fluoride application alone in increasing microhardness of primary teeth enamel, regardless of order of treatments or laser power.