Bond strength of restorative material to dentin submitted to bleaching and Er:YAG laser post-treatment.

Abstract

The purpose of this study was to assess the bond strength of a restorative material to bleached dentin, pretreated with Er:YAG laser. Laser irradiation for dental surface treatment may increase the bond strength of restorative material to tooth surface. There are no reports of using Er:YAG laser on dentin bleached with 35% hydrogen peroxide. Forty maxillary canines were sectioned, resulting in 80 fragments (5×5 mm) of intracoronary dentin that were divided into eight groups (n=10) according to the dental bleaching (present or not), surface conditioning (with or without laser) and the post-bleaching time to perform restoration (immediately or 7 days). The bleached specimens received two applications of 38% hydrogen peroxide. Er:YAG laser was applied for 20 sec with 400 mJ/15 Hz. Restorative procedure was performed using phosphoric acid, an adhesive system, and resin using a split Teflon matrix. The specimens were submitted to shear bond strength test and the data (MPa) were analyzed by ANOVA and Tukey's test (α=0.05). There were significant differences among the three factors (p<0.05). The highest values were obtained for unbleached specimens compared with bleached, for those treated with laser compared with those only conditioned with acid, and for those restored after 7 days compared with those having immediate restoration. In the interaction of factors, the bleached specimens treated with laser and restored immediately were statistically similar (p>0.05) to those bleached and restored after 7 days. Er:YAG laser can restore the bond strength of the dentin/restorative material interface even if the restoration is performed immediately after bleaching.