Purpose: This study evaluated the shear bond strength of repaired new and old composite resin restorations after surface treatment with diamond bur, aluminum oxide jet, and Er:YAG laser, with the aim of developing a new ultraconservative technique to repair unsatisfactory composite resin restorations. Materials and Methods: Thirty-six hybrid composite resin blocks were made. The blocks were repaired with nanohybrid composite resin and then subjected to shear bond strength testing of the repair interfacial bond strength. ANOVA and the Tukey test were used at a significance level of 5%. Results: The highest average bond strength values were found when the old composite resin restorations were repaired with the diamond bur and the surface ablated with Er:YAG laser (2.15 W/cm2). Conclusion: The results of this study suggest that the Er:YAG laser system can be used effectively for composite resin repair.

Keywords: ablation, diamond bur, Er:YAG laser, jet abrasion