Effect of different concentrations of carbamide peroxide and green tea extract on the color and shear bond strength of enamel ? an in vitro study

Aim: The aim of this in vitro study is to evaluate the change in color and shear bond strength of enamel bleached with different concentrations of carbamide peroxide and green tea extract solution. Materials and Methods: The specimens are grouped as follows:Group ?A: 16 % carbamide peroxide,Group ?B: 16% carbamide peroxide & green tea extract, Group ?C: 21% carbamide peroxide, Group -D: 21% carbamide peroxide & green tea extract. Specimens are tagged and colors are recorded using Vita classic shade guide. Two concentrations of carbamide peroxide gels are applied onto the enamel fragments of extracted human teeth of respective groups. Green tea extract, an antioxidant is later applied on bleached specimens of group B and group D. These specimens are then stored in artificial saliva for 24 hrs. Surfaces of all the specimens are examined for color using shade guide followed by shear bond strength test. Results: At the end of the whitening process, no change was seen in the value of the shade before and after treatment with cabamide peroxide gel and green tea extract, but a significant difference in the shade was seen in group D after the application of carbamide peroxide gel and green tea extract. The ANOVA did not show differences in shear bond strengths with the various treatment agents. No statistically significant difference was seen between all the four treatment groups, but the groups B and D in which antioxidant was used, showed slightly higher bond strength when compared to groups A and group C. Conclusion: Within the limitations of this study, though increase in the concentration of carbamide peroxide improves the lightening of enamel surface, it affecs the bond strength of the specimens bonded immediately with the adhesive resin.