Bond Strength of Composite on Bleached Enamel after Antioxidant Treatment

Objective: The purpose of this study was to investigate the effect of antioxidant treatment after bleaching (carbamide peroxide (CP)) on the shear bond strength of two different bonding systems to enamel. Methods: A total of 60 human mandibular incisors were used. A flat enamel surfaces were obtained with 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 CP. They were bonded with Single Bond (3M ESPE) or Clearfil SE (Kuraray) 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. After the specimens were bonded, they were tested in shear until failure. Fracture analysis of the bonded enamel surface was performed using stereo microscope. Results: The shear bond strength data was subjected to two-way analysis of variance followed by Tukey's multiple comparisons test at a significance level of P < 0,05. Bond strengths of both adhesives were reduced after bleaching but were reversed following sodium ascorbate treatment (p>0.05). Conclusion: The antioxidant treatment immediately treatment after bleaching was effective in reversing the bond strength of both adhesive systems.