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The Effect of Different Forms of Antioxidant Surface Treatment on the Shear Bond Strength of Composite Restorations to Bonded to Office- Bleached Enamel

Amal S. Al Awdah, Al Hanouf A. Al Habdan, Nourah Al Muhaisen and Raba’a Al Khalifah

Purpose: To investigate the effects of two different forms of sodium ascorbate (solution and gel) as antioxidant surface treatments in reversing the compromised bond strength after vital in-office tooth bleaching with 38% hydrogen peroxide. Materials and Methods: The study included 25 natural teeth (premolars). The crown of each tooth was sectioned in the mesio-distal direction to use both the buccal and lingual enamel surfaces for the bonding procedures. Then, the samples were randomly divided into 5 groups (n=10), according to different treatment options of bleaching and bonding. The specimens were then subjected to a shear bond strength test using a universal testing machine. The modes of bond failure were determined using a stereomicroscope and a digital camera. Results: Bleached enamel immersed in saliva for two weeks before bonding and nonbleached enamel surfaces showed significantly higher bond strengths to composite resin than did enamel surfaces bonded immediately after bleaching without an antioxidant surface treatment (P=.000). There was no significant difference between delaying bonding for two weeks after bleaching and bonding without any bleaching procedure (P=.999). A resin composite bonded to bleached enamel surfaces that were treated with both antioxidants in the different solution forms showed a significantly higher shear bond strength than did a resin composite bonded immediately after bleaching (P=.000). There was no significant difference between the use of sodium ascorbate solution or gel in the shear bond strength (P=.999). It was noted that most the adhesive failures in this study were at the adhesive/resin interface Conclusion: Bonding resin composite immediately after enamel bleaching with 38% hydrogen peroxide reduced the shear bond strength. Both the gel and solution forms of 10% sodium ascorbate can reverse the reduced bond strength after in-office enamel bleaching.