In Vitro Evaluation of the Effect of Different Surface Treatments of a Hybrid Ceramic on the Microtensile Bond Strength to a Luting Resin Cement

Abstract Introduction: The aim of this present study was to investigate the effect of different surface treatments of a hybrid ceramic, Vita Enamic (VE), on the micro-tensile bond strength (µ-TBS) to a resin cement.Materials and methods: ۱۰ blocks (۳×۱۰×۸ mm)were retrieved from the original blocks and divided into five groups according to the different surface treatment performed: Groups ۱: ۳۵% Acid phosphoric for ۶۰ seconds (PA); group ۲: Sandblasting with ۵۰µm Al۲O۳ particles for ۱۰ seconds (SB); groups ۳: ۹.۵% hydrofluoric acid for ۶۰ seconds(HF), group ۴: Er:YAG laser (۲ W,۱۰ Hz) (ER۱), group ۴: Er:YAG laser (۳ W, ۱۰ Hz) (ER۲). All treated surfaces were salinizedand the blocks with similar surface treatments were bonded together using a dual cured resin cement and light cured. After ۲۴-hour storage in water, blocks were cut into beams(۱mm۲). Half of the specimens in each group(n=۱۶) were tested immediately and the rest were subjected to thermocycling between ۵°C and ۵۵°C for ۶۰۰۰ cycles before µ-TBS test at a crosshead speed of ۰.۵ mm/min. The data were analyzed using two-way ANOVA and Tukey HSD tests considering ۰.۰۵ as significance level. The failure mode was evaluated using a stereomicroscope.Result: µ-TBSwas clearly influenced by surface treatment methods(P˂۰.۰۰۱) and thermocycling significantly decreased the bond strength values in all groups (P=۰.۰۰۷). The highest value (۶۶.۰۷ MPa±۱۱.۳) was obtained for HF groups with no thermocycling and the lowest values were observed in laser groups with no significant difference among different irradiation parameters. Adhesive failure was mainly observed in PA and SB groups while mixed failure was predominantly shown in laser and HF groups.Conclusion: This study demonstrates that surface treatment of VE with HF and salinization can improve the bond strength to a dual cured resin cement and Er:YAG laser irradiation with the evaluated parameters did not promote adhesion of the resin cement to VE. Keywords: Er YAG laser Hybrid Ceramic Tensile strength Surface treatment