Er:YAG laser effect on bovine enamel microhardness after erosive challenge

Purpose: The aim of this study was to evaluate longitudinal enamel microhardness after treatment with laser and fluoride followed by exposure to an erosive challenge. Methods: Twenty-four specimens were obtained from bovine enamel (2x3 mm), polished and randomly divided in to four groups (n=6) according to the preventive treatments: G1 - Er:YAG laser; G2 - laser + fluoride; G3 - fluoride; and G4 - fluoride + laser. Half of the enamel surface was covered with nail varnish (control area) and the other half exposed to the preventive treatments and erosive challenge. The laser was irradiated for 10s at 80 mJ/2Hz, and the fluoride gel was applied for 4 min. Each specimen was individually exposed to the soft drink Coca-Cola 4 times/day for 1 minute for a total of 5 days. The specimens were embedded in resin, sectioned in half, flattened and polished. After microhardness analysis, the results were averaged using the Kruskal-Wallis test. Results: Groups 2 and 4 had decreased enamel demineralization compared to the other groups but did not differ from each other: G1= -30.95; G2=19.62; G3= -20.5; and G4=29.67. Conclusion: It can be concluded that laser irradiation associated with fluoride application can effectively reduce enamel demineralization.