Bond Strength of Composite after 10%Sodium-Ascorbate Treatment on Bleached Enamel

Objective: The purpose of this study was to determine the effect of antioxidant treatment after an in-office bleaching (hydrogen peroxide (HP)) on enamel shear bond strength of two different bonding systems. Methods: A one-bottle total-etching adhesive system, Single Bond (3M,ESPE) and a self-etching system, Clearfil SE Bond (Kuraray), were used. Sixty human mandibular incisors were mounted in self-curing resin and the facial enamel surfces were ground wet on 600-grit SiC paper. The twenty enamel specimens were treated with artificial saliva (control) and fourty enamel surfaces were treated further treatment with or without 10% sodium ascorbate after bleaching with HP. They were bonded with Single Bond (3M ESPE) or Clearfil SE Bond and restored with a composite (Clearfil ST, Kuraray). Group 1a,b; Specimens in the control group were not bleached. Group 2a,b; specimens were bonded immediately after bleaching. Group 3a,b; specimens were treated with 10% sodium ascorbate. All specimens per test group were stored in 37 °C artificial saliva for 24 hours, then they were tested in shear until failure. Fracture analysis of the bonded enamel surface was performed using stereomicroscope. Results: The shear bond strength data was analyzed by a two-way analysis of variance, and multiple comparisons were done by Tukey's test at a significance level of P < 0,05. The composites bonded with both adhesives immediately after bleaching revealed significantly lower shear bond strengths than those of unbleached enamel (p<0.05). For both of adhesive systems, when the antioxidant-treated groups were compared with unbleached group (control), no statistically significant differences in shear bond strength were noted (p>0,05). Conclusion: The antioxidant treatment immediately treatment after office-bleaching was effective in reversing the bond strength of both adhesive systems.