In Vitro Effect of Bleaching With ۸۱۰ nm and ۹۸۰ nm Diode Laser on Microhardness of Self-cure and Light-Cure Glass Ionomer Cements

Abstract Introduction: This study sought to assess the effect of bleaching combined with irradiation of ۸۱۰ nm and ۹۸۰ nm diode laser on microhardness of ۲ commonly used self-cure and light-cure glass ionomer cements (GICs) in comparison with conventional bleaching (without laser). Methods: In this in vitro, experimental study, ۶۰ samples were fabricated of A۲ shade of Fuji IX and Fuji II LC GICs (n = ۳۰) and each group was divided into ۳ subgroups (n = ۱۰). The first subgroups were subjected to bleaching with Opalescence Xtra Boost plus ۹۸۰ nm diode laser irradiation. The second subgroups were subjected to bleaching with Opalescence Boost plus ۸۱۰ nm diode laser irradiation and the third subgroups were subjected to bleaching with Opalescence Xtra Boost without laser. Microhardness was measured at baseline and after the intervention using Vickers hardness tester. The data were analyzed using two-way analysis of variance (ANOVA) (P < ۰.۰۵).Results: Microhardness decreased in all subgroups after the intervention (P < ۰.۰۰۱) irrespective of the type of GIC (P = ۰.۲۰۱) or surface treatment (P = ۰.۵۷۰). The baseline microhardness of the three subgroups within each group of GIC was not significantly different (P = ۰.۴۵۶), but the baseline microhardness of conventional GIC was significantly higher than that of resin modified GIC (P = ۰.۰۰۴).Conclusion: Bleaching with/without laser irradiation decreases the microhardness of GICs. The baseline microhardness of conventional GIC is higher than that of resin modified GIC. Keywords: Glass Ionomer Cements Hardness Lasers Tooth Bleaching