Effect of green tea extract antioxidant on dentin shear bond strength and resin-tag penetration depth after non-vital bleaching

Background: 35% Hydrogen peroxide (H2O2) as an active material for internal bleaching can produce free radicals that affect resin tag penetration into the dentinal tubules. Application of 10% and green tea (GT) extract antioxidant after 2 minutes are expected to remove radical residues increase dentin shear bond strength tags depth non-vital bleaching. Methods: 30 extracted healthy human premolars were cut horizontally mm from Cemento Enamel Junction margin crown part, then in a mesio-distal direction two parts. The specimens divided five groups: normal dentin, post delayed weeks, GT, GT group. Non-vital walking bleach with H2O2 gel was done all groups except control Soon after, applied on minutes, rinsed-off aquabidest dried. All etched bonded etch-and-rinse adhesive system filled composite. assessment carried out using Universal Testing Machine (UTM) cross-head speed 0.5 mm/minute. Confocal laser scanning microscopy (CLSM) wavelength 560 nm lens magnification 40x used analyze penetration. Data analyzed by one way ANOVA t-test. Results: There significant difference between applying (p < 0.05). group resulted significantly longer than group. Conclusions: application is more effective increasing composite bleaching.