Effect of Er:YAG Laser Irradiations on Shear Bond Strength of Three Self-Adhesive Resin Cements to Dentin

Objective: The purpose of this study was to evaluate the influence of Er:YAG laser irradiation on shear-bond strength of self-adhesive resin cements to dentin. Background data: Different laser-irradiation settings are used for dentin-surface pretreatment, which may affect the bond strength of resins. Methods: Fourty-five extracted third molars were selected, sectioned in a mesiodistal direction, and 90 tooth slabs were obtained. The teeth were ground to expose the dentinal hard tissue with 320- and 600-grit silicon carbide disks. The specimens were randomly assigned to nine groups (n = 10). Surfaces for each group were laser irradiated with 30 Hz/70 mJ (2.1 W), 30 Hz/160 mJ (4.8W), or non-irradiated (control) for each resin cement (SmartCem2, RelyX Unicem, Multilink Automix). All specimens were stored in distilled water at 37 degrees C for 24 h after luting. Shear-bond testing was carried out by using a Universal testing machine with a crosshead speed of 0.5 mm/min. Data were analyzed with one-way ANOVA and post hoc Tukey HSD tests (p<0.05). Results: The highest bond-strength value was obtained with SmartCem2, which was irradiated with Er: YAG laser (30 Hz/160 mJ). The lowest values were exhibited in the control group of SmartCem2, RelyX Unicem and Multilink Automix, respectively (4.92 +/- 1.68, 7.17 +/- 2.88, and 7.93 +/- 3.05). Conclusion: The 2.1-W and 4.8-W laser ablation did not show any statistically difference for RelyX Unicem and Multilink Automix materials. However, in the SmartCem2 group, laser irradiated with 30 Hz/160 mJ application increased the bond-strength values, and the highest bond-strength results were obtained in this group.