Background: Laser therapy, along with the use of fluoridated compounds is a novel technique suggested for caries prevention. Casein phosphopeptide amorphous calcium phosphate (CPP-ACP) is another product suggested for this purpose. This study compared the effect of CPP-ACP and fluoride with/without Erbium, chromium-doped yttrium, scandium, gallium, and garnet laser irradiation on enamel microhardness of permanent teeth. Materials and Methods: This in vitro experimental study evaluated 35 extracted third molars. The teeth were decoronated, and the crowns were split into buccal and lingual halves. The samples were randomly divided into seven groups ( n = 10) of GC Tooth Mousse, MI Paste Plus, laser, fluoride varnish, laser + GC Tooth Mousse, laser + MI Paste Plus, and laser + fluoride varnish. The baseline microhardness was measured before the intervention. After the intervention, the samples were kept in artificial saliva for 1 h and were then immersed in the demineralizing solution for 3 h followed by 21 h of immersion in the remineralizing solution for a total period of 12 days. Finally, the teeth were kept in the remineralizing solution for 2 more days. The secondary microhardness of the teeth was then measured. Data were analyzed using the Shapiro–Wilk test, two-way ANOVA, and Tukey's Honestly Significant Difference test. Results: The fluoride varnish (14.31%) and laser + fluoride varnish (18.79%) groups experienced minimum reduction in microhardness, while the GC Tooth Mousse group experienced maximum reduction in microhardness (91.64%) ( P < 0.001). Laser irradiation before the application of remineralizing agents increased the microhardness only in laser + GC Tooth Mousse group ( P < 0.001). Conclusion: Fluoride varnish increased the enamel microhardness, while GC Tooth Mousse had no such effect. Laser therapy before the application of remineralizing agents did not significantly enhance enamel resistance to demineralization.

Fissure sealant application is an efficient method for dental caries prevention. Self-etch fissure sealants (SE-FS) eliminate the separate etching step for bonding. The present study investigated the micro-shear bond strength (μSBS) of a SE-FS (Prevent seal ® , Itena©, Paris, France) to enamel pretreated with different methods including Er,Cr:YSGG laser, under noncontaminated and saliva-contaminated conditions. Sixty human premolars were sectioned into halves and randomly assigned into two groups of saliva-contaminated and noncontaminated. Each group was further divided into six subgroups (N = 10) of different enamel pretreatment methods: (Laser+SE-FS), (Acid-etch+SE-FS), (Laser+Acid-etch+SE-FS), (Mechanical preparation+SE-FS), (SE-FS), and (Acid-etch+Bonding+Conventional fissure sealant) as positive control. The μSBS of the sealant material to enamel was measured in all subgroups. The two-way ANOVA and Tukey tests were applied at P < 0.05. Saliva contamination had a significant effect on μSBS (P < 0.001), while pretreatment with laser or acid etching did not significantly affect the μSBS (P = 0.251). The μSBS of SE-FS to untreated enamel surface was significantly lower than the positive control (P = 0.035). The μSBS value in the subgroup receiving laser+etching+SE-FS was significantly higher than the remaining five subgroups (P < 0.001). Other pairwise comparisons were not statistically significant (P > 0.05). Acidetch and Er,Cr:YSGG laser exert a synergic effect on μSBS of Prevent Seal ® , irrespective of saliva contamination.