Evaluation, in vitro, of Aged Composite Resin Repair

Objectives: The present study aims to evaluate in vitro the influence of surface treatment of aged resin submitted a repair procedure. Materials and Methods: 28 cylinders of resin composite made with a metal matrix of 4 mm in height and 6mm in diameter. The cylinders were randomly divided into seven groups according to surface treatment. The specimens were evaluated in 24h and after 1 year of aging in artificial saliva. Surface treatments performed: G1, the surfaces of the cylinders were blasted with aluminum oxide, G2, then blasting the application of silane, G3, blasting followed by application of adhesive; G4, application of hydrofluoric acid, 9,6% hydrofluoric acid, G5 followed by application of silane and G6, hydrofluoric acid followed by application of adhesive. In the control group (CG), the resin cylinders received no treatment prior  the repair resin aplication. After surface treatment, composite repairs were performed in the cylinders with the same metal matrix. The cylinders were then sectioned into beans of ​​0.5 mm² bonding area and submitted to microtensile bond strength in a universal testing machine Emic DL-2000, at the speed of 1mm/min. The bond strength values ​​were calculated in MPa. Data analysis was performed using ANOVA with a significance level of 5%. Results: The groups treated with aluminum oxide showed the highest mean microtensile bond strength than groups treated with hydrofluoric acid. The group Al₂O₃+bond, had no statistical difference between 24h and 1 year. Furthermore, when analyzed only those groups of 1 year of storage this group showed a statistically significant difference when compared to others, except Al₂O₃+silane. However, Al₂O₃  showed difference when compared  24h and 1 year results. Conclusion: We conclude that aging of the composite influenced the tensile bond strength of repair, and blasting with aluminum oxide followed by application of adhesive showed the best result.