Materials and methods. Sixty eight cylindrical samples of a silorane-based composite resin (Filtek Silorane) were prepared and randomly divided into 4 groups as follows: group 1: without surface treatment groups 2, 3 and 4 with surface treatments using Er Cr:YSSG, Nd:YAG, and CO2 lasers, respectively. A positive control group (group 5) was assigned in order to measure cohesive strength. Repair shear bond strength values were measured and data was analyzed using one-way ANOVA and a post hoc Tukey test at a significance level of α=0.05.

  Results. There were statistically significant differences in repair shear bond strength values between group 2 and other groups (P < 0.05) and between group 1and groups 3and 4 (P < 0.001) however, there were no significant differences between groups 3 and 4 (P = 0.91).

  Conclusion. The repair shear bond strength of silorane-based composite resin was acceptable by surface treatment with lasers.