Effect of irrigation times of sodium ascorbate on bond strengths to bleached enamel using two adhesive systems.

Abstract

Objectives: To evaluate the effect of different irrigation times of 10% sodium ascorbate on microshear bond strengths of two adhesives: Adper™ Single Bond 2 and Clearfil SE Bond, to enamel bleached with 10% carbamide peroxide. Materials and methods: Sixty sound human premolars were divided into 5 groups regarding to treatment of facial enamel surfaces: 1 no treatment (unbleached enamel), 2 bleached with 10% carbamide peroxide (VivaStyle 10%), the other three groups were bleached and followed by irrigation with 10% sodium ascorbate for 30 sec, 1 min and 10 min respectively. Enamel surface of all specimens were bonded with one of the two adhesives and then restored with a resin composite. The microshear bond strength testing was performed using a universal testing machine at a crosshead speed of 1 mm/min after storage in distilled water at 37°C for 24 hours. The data were analyzed using two-way ANOVA and post-hoc multiple range test (p<0.05). Results: Irrigation with sodium ascorbate for 10 min could reverse the bond strength of bleached enamel in group using AdperTM Single Bond 2 to the same level as that of the control group (p<0.05). However, irrigation with sodium ascorbate had no effect on the bond strength of bleached enamel bonded with Clearfil SE Bond. Conclusion: Pretreatment with sodium ascorbate for 10 min before composite restoration improved the bond strengths of bleached enamel when AdperTM Single Bond 2 was used.