restoring the bond strength of composite resin to bleached enamel with epigallocatechin-3-gallate, hypericin, and resveratrol

Objective: this study investigated the effects of three herbal antioxidants on restoring the compromised bond strength of composite resin to bleached enamel.methods: in this in vitro study, 50 extracted human central incisors were divided into five groups. group a (negative control) received no bleaching or antioxidant treatment. the teeth in groups b to e were bleached and subjected to the following surface treatment: group b (positive control): no surface treatment; group c: application of 5% epigallocatechin-3-gallate (egcg); group d: application of 10% hypericin; and group e: application of 10% resveratrol. the antioxidant solutions were applied for 10 minutes. all specimens were restored with a nanohybrid composite resin, and shear bond strength (sbs) was measured 24 hours after restoration using a universal testing machine. data were analyzed using one-way anova and tukey's post hoc test with a significance set at p<0.05.results: anova revealed a significant difference in sbs among the groups (p=0.011). the bleaching alone (group b) significantly reduced sbs compared to other groups (p< 0.05). all three antioxidants (5% egcg, 10% hypericin, 10% resveratrol) fully restored sbs to the level of the non-bleached control (group a), with no significant differences between them (p>0.05). among antioxidants, 5% egcg showed the highest mean sbs (5.06 ± 1.57 mpa), followed closely by 10% hypericin (4.92 ± 1.05 mpa) and 10% resveratrol (4.79 ± 1.16 mpa).conclusions: all herbal antioxidants, including 5% egcg, 10% hypericin, and 10% resveratrol, effectively improved the bond strength of composite resin to recently bleached enamel