THE EFFECT OF ANTIOXIDANTS ON THE BOND STRENGTH OF RESIN COMPOSITE TO BLEACHED ENAMEL

Aim : This study aimed to assess the effect of treating bleached enamel with antioxidants on the value of shear bond strength of resin composite to enamel. Also, a comparison was set between the natural antioxidant used (5% pomegranate solution) and the chemical one (10 % sodium ascorbate gel).
Materials and Methods: Fifty six human freshly extracted sound upper anterior teeth were used. The specimens were randomly divided into four main groups as follow : Group I : control(no bleaching) ; Group II : bleached then treated with the chemical antioxidant ; Group III : bleached then treated with the natural antioxidant; Group IV : bleached with no antioxidant treatment. Each group was further sub-divided into two sub-groups according to whether the restoration was performed immediately or delayed (after one month incubation in artificial saliva) (n=7). The variables were as follow: No bleaching immediate restoration (control) ; no bleaching delayed restoration after incubation for one month in artificial saliva ; bleached followed by application of a chemical antioxidant (10% sodium ascorbate gel) for 10 min then immediate restoration;bleached followed by application of a chemical antioxidant (10% sodium ascorbate gel) for 10 min then delayed restoration; bleached followed by application of a natural antioxidant (5% pome granate solution) for 10 min then immediate restoration ; bleached followed by application of a natural antioxidant (5% pome granate solution) for 10 min then delayed restoration ; bleached with no application of an antioxidant then immediate restoration ; bleached with no application of an antioxidant then delayed restoration. The data were statistically analyzed using two way ANOVA test, one way ANOVA test, Tuckey’s post-hoc tests and pair wise student T-test.
Results : Regarding the mean shear bond strength values (immediate restoration) ; the control sub-group (immediately restored) demonstrated the highest values followed by the bleached sub-groups treated with the natural antioxidant (5% pomegranate solution), then the bleached sub-groups treated with the chemical antioxidant (10% sodium ascorbate gel). The bleached sub-groups that were not treated with the antioxidants showed the least values. Regarding the sub-groups that undergone a delayed investigation ; the sub-groups treated with the natural antioxidant demonstrated the highest shear bond strength values followed by the sub-groups treated with chemical antioxidants then the control group while the bleached sub-groups that were not treated with the antioxidants showed the least values of mean shear bond strength