The Effect of 10% Sodium Ascorbate and Er: YAG Laser on the Microtensile Bond Strength of Composite Resin to Bleached Enamel

Abstract

Background: There are various methods proposed to prevent the reduction of substrate micro tensile bond strength to bleached enamel. Therefore, this study aims to evaluate and compare the effectiveness of two common methods, namely 10% sodium ascorbate and Er:YAG laser irradiation, in increasing the microtensile bond strength of composite resins to bleached enamel. Methods: In this in vitro study, 72 maxillary premolar teeth were divided into four equal groups: bleached control group, unbleached control group, treated with 10% sodium ascorbate, and Er:YAG laser-treated group (60 mJ, frequency = 10 Hz, and power of 0.6 W with a 400-µm diameter tip). The samples were cut by a CNC cutting machine for a microtensile bond strength test. Results: The Er:YAG laser group showed the highest mean bond strength (27.3 MPa), while the bleached control group had the lowest (15.06 Mpa). There was a significant difference between the bleached and unbleached control groups (P<0.001). Samples prepared with 10% sodium ascorbate and the Er:YAG group had higher tensile bond strength than the bleached control group (P<0.0001). Tensile bond strengths were not significantly different between the 10% sodium ascorbate and the Er:YAG laser preparation groups (P=0.361). Conclusion: The findings of this study indicate that the microtensile bond strength of composite resins to bleached enamel can be increased by 10% sodium ascorbate and Er:YAG laser irradiation.