Comparison of the Effect of Three Mechanical Surface Treatments on the Repair Bond Strength of a Laboratory Composite

Objective: This study compared the effects of three mechanical surface treatments, including diamond bur, air-abrasion, and Er, Cr: YSGG laser on the repair bond strength of a laboratory composite resin. Background Data: A proper bonding must be created between the existing composite and the new one for successful repair. Materials and Methods: Sixty cylindrical specimens of a laboratory composite resin (Gradia) were prepared and randomly divided into four groups (n = 15). Groups 2-4 were treated with diamond bur, air-abrasion, and Er, Cr: YSGG laser, respectively; group 1 was the control group, without any mechanical surface treatment. The topographical effects of different mechanical surface treatments were characterized by atomic force microscope. Silane and a bonding agent (Single Bond) were used in all of the groups before adding a direct resin composite. Then, the specimens were subjected to a shear bond strength test. Failure modes were evaluated under a stereomicroscope. All data were analyzed by one-way ANOVA and Tukey test at a significance level of p < 0.05. Results: There were statistically significant differences in bond strengths between the groups (p < 0.0005). Differences in bond strengths between group 1 and the other groups were significant (p < 0.0005). Furthermore, there were significant differences in bond strengths between group 2 and groups 3 and 4 (p < 0.0005), while the bond strength differences between groups 3 and 4 were not significant. Conclusion: Based on the results of this study, Er, Cr: YSGG laser was confirmed to be as effective as air-abrasion for laboratory composite repair.