Reversal of deleterious effect of extracoronal in- office bleaching on shear bond strength of composite resin to bleached enamel: Effect of delayed restoration and different antioxidants application - in vitro study

Objective:The objective of this in - vitro study was to evaluate the effect of different antioxidants in reversal of of deleterious effect of bleaching on shear bond strength of composite resin to bleached enamel.Materials and methods: Seventy bovine incisors were used. The specimens were randomly divided into seven groups (10 specimens each) as follow: Group 1: no bleaching treatment and no antioxidant application. Group 2: bleaching only without antioxidant application and immediate composite resin application after bleaching. Group 3: bleaching only without antioxidant application and delayed composite application (after 2 weeks) of storage. Group 4: bleaching and application of 10% Alpha-tocopherol.Group 5: bleaching and application of 6% cranberry extract. Group 6:bleaching and application of 10% sodium ascorbate. Group 7: bleaching and application of 10% green tea. 40% hydrogen peroxide (Opalescence Xtra Boost 40%, Ultradent, South Jourdan, UT, USA) was used. Composite resin Tetric N -Ceram was used. The shear bond strength was measured using a universal testing machine. Results: one-way ANOVA test revealed significant differences in shear bond strength among the tested groups (p < 0.001). Bond strength significantly decreased after bleaching. There was no significant difference in shear bond strength reversed using10% Alpha-tocopherol, 10% sodium ascorbate and 10% green tea and delayed restoration. Whereas the difference was significant between group 5(6% cranberry extract) and other antioxidants groups. Conclusion: The results obtained from the use of antioxidants using (10% Alpha-tocopherol, 10% sodium ascorbate and 10% green tea extract) is approximately the same as the delayed restoration.