Effect of sodium ascorbate and delayed treatment on the shear bond strength of composite resin to enamel following bleaching.

Abstract

The effect of bleaching on enamel surfaces, as well as exploring methods of preventing the weakening of bond strength of two different adhesives to bleached enamel surfaces. This study compared the shear bond strength (SBS) of two different adhesives on bleached enamel immediately after bleaching, with a 1-week delay, and following application of an antioxidizing agent after bleaching. Materilas and Method: The enamel surfaces of 140 incisors were divided into 14 groups. Two unbleached enamel groups (n = 20) were prepared as negative controls of the Adper Single Bond 2 total-etch and Clearfil Tri S Bond self-etch adhesives. The remaining surfaces were randomly divided into two bleaching groups treated with 35% Beyond Max (n = 60) and 38% Opalescence Xtra Boost (n = 60). Each bleaching group was then divided into two subgroups using the total and self-etch adhesive systems. Specimens were bonded immediately after bleaching, after treatment with 10% sodium ascorbate (SA) gel, or after 1-week of immersion in artificial saliva. All groups were restored with composite resin. After thermocycling, SBS was measured and data were analyzed. In the control groups, there was no statistically-significant difference in SBS between self-and total-etch adhesives. Among all bleaching groups, no statistically-significant differences in SBS were noted, although the SA-treated delayed bonding (1-week) groups had the highest values. The lowest values were noted for the groups bonded immediately after bleaching.