Tabriz University of Medical Sciences Journal of Dental Research, Dental Clinics, Dental Prospects 2008-210X 8 2 2014 06 11 Effect of Mechanical Surface Treatment on the Repair Bond Strength of the Silorane-based Composite Resin 61 66 10.5681/joddd.2014.011 EN Parnian Alizadeh Oskoee Soodabeh Kimyai Elham Talatahari Sahand Rikhtegaran Fatemeh Pournaghi-Azar Jafar Sajadi Oskoee Journal Article 10.5681/joddd.2014.011 2014 07 17 Background and aims. A proper bond must be created between the existing composite resin and the new one for success-ful repair. The aim of this study was to compare the effect of three mechanical surface treatments, using diamond bur, air abrasion, and Er,Cr:YSGG laser, on the repair bond strength of the silorane-based composite resin. Materials and methods. Sixty cylindrical composite resin specimens (Filtek Silorane) were fabricated and randomly di-vided into four groups according to surface treatment: group 1 (control group) without any mechanical surface treatment, groups 24 were treated with air abrasion, Er,Cr:YSGG laser, and diamond bur, respectively. In addition, a positive control group was assigned in order to measure the cohesive strength. Silorane bonding agent was used in groups 14 before add-ing the new composite resin. Then, the specimens were subjected to a shear bond strength test and data was analyzed using one-way ANOVA and post hoc Tukey tests at a significance level of P < 0.05. The topographical effects of surface treat-ments were characterized under a scanning electron microscope. Results. There were statistically significant differences in the repair bond strength values between groups 1 and 2 and groups 3 and 4 (P < 0.001). There were no significant differences between groups 1 and 2 (P = 0.98) and groups 3 and 4 (P= 0.97). Conclusion. Surface treatment using Er,Cr:YSGG laser and diamond bur were effective in silorane-based composite resin repair.