Effect of various laser surface treatments on repair shear bond strength of aged silorane-based composite

Introduction: successful repair of composite restorations depends on a strong bond between the old composite and the repair composite. this study sought to assess the repair shear bond strength of aged silorane-based composite following surface treatment with nd:yag,er,cr:ysgg and co2 lasers. methods: seventy-six filtek silorane composite cylinders were fabricated and aged by 2 months of water storage at 37°c. the samples were randomly divided into 4 groups (n = 19) of no surface treatment (group 1) and surface treatment with er,cr:ysgg (group 2),nd:yag (group 3) and co2 (group 4) lasers. the repair composite was applied and the shear bond strength was measured. the data were analyzed using one-way analysis of variance (anova) and tukey post-hoc test. prior to the application of the repair composite,2 samples were randomly selected from each group and topographic changes on their surfaces following laser irradiation were studied using a scanning electron microscope (sem). seventeen other samples were also fabricated for assessment of cohesive strength of composite. results: the highest and the lowest mean bond strength values were 8.99 mpa and 6.69 mpa for er,cr:ysgg and control groups,respectively. the difference in the repair bond strength was statistically significant between the er,cr:ysgg and other groups. bond strength of the control,nd:yag and co2 groups was not significantly different. the sem micrographs revealed variable degrees of ablation and surface roughness in laser-treated groups. conclusion: surface treatment with er,cr:ysgg laser significantly increase the repair bond strength of aged silorane-based composite resin.