Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 13 4 2016 12 31 244 251 EN Zahra Khamverdi Professor, Dental Research Center, Dental School, Hamadan University of Medical Sciences, Hamadan, Iran. Parvin Khadem Assistant Professor, Department of Operative Dentistry, Faculty of Dentistry, Khorasgan Azad University, Isfahan, Iran Aliraza Soltanian Associate Professor, Department of Biostatistics, Faculty of Health, Hamadan University of Medical Sciences, Hamadan, Iran Maryam Azizi Dentist, Hamadan, Iran 2016 03 07 2016 08 30 Objectives: A reduction in bond strength of composite to bleached enamel has been reported immediately after bleaching treatment. Application of some antioxidant agents may decrease the adverse effects of whitening agents on bond strength and enhance composite bond to enamel. This study aimed to assess the effect of green tea, sodium ascorbate, sage and grape seed extract on bond strength of composite to bleached enamel. Materials and Methods: In this in-vitro study, 90 human enamel surfaces were randomly divided into six groups as follows (n=15): G1, no bleaching; G2, bleaching with 40% hydrogen peroxide (HP); G3, HP+1000 μmol epigallocatechin gallate (EGCG) for 10 minutes; G4, HP+10% sodium ascorbate for 10 minutes; G5, HP+10% sage for 10 minutes and G6, HP+5% grape seed extract for 10 minutes. The specimens were bonded to composite in all groups. The shear bond strength of specimens was measured in Megapascals (MPa). Data were analyzed using one-way ANOVA and Tukey’s HSD test (α=0.05). Results: The highest and the lowest mean shear bond strength values were observed in group 1 (22.61±3.29MPa) and group 2 (5.87±1.80MPa), respectively. The reduction in bond strength in group 2 was greater than that in other groups (P<0.001). No significant difference was found among groups 1, 3, 4, 5 and 6 (P>0.05).  Conclusions: All the herbal antioxidants used in this study equally compensated for the reduced bond strength of composite to bleached enamel.   https://fid.tums.ac.ir/index.php/fid/article/view/1115 https://fid.tums.ac.ir/index.php/fid/article/download/1115/894