Effect of antioxidant agent on bond strength of composite-resin and resin modified glass ionomer to bleached enamel

The enamel bond strength of resin containing materials is reduced right after bleaching. The aim of this study was to investigate the neutralizing effect of an antioxidant agent on bond strength of bleached enamel, using composite resin (Z100, 3M, ESPE, USA) and a resin modified glass ionomer (Vitremer, 3M, ESPE, USA) in this investigation. Likewise, it is intended to compare the results of this procedure with delayed bonding (for one week) effects. Ninety-six human sound 3rd molars were divided into eight groups. After initial preparations, the buccal enamel surface of the specimens in groups one and five were immediately bonded with composite resin (CR) and resin modified glass ionomer (RmGI) cylinders. The samples in other groups were all bleached six hours a day for five days consecutively. The specimens in groups two and six were bonded with CR and RmGI immediately after bleaching. The specimens in groups three and seven were immersed in distilled water at 37◦C for one week and groups four and eight, were exposed to 10% sodium ascorbate hydro gel for ten hours after bleaching and they were bonded with CR and RmGI immediately. Using DARTEC machine, the shear bond strength (SBS) were recorded for all samples. Data analyses were conducted by using One-way ANOVA and Tukey statistical tests. The mean SBS value in group two was significantly lower than other CR groups (P=0.045). RmGI did not bond to bleached enamel (group six).There was no significant difference between other RmGI groups (P>0.05). Both One week delay and application of 10% sodium ascorbate hydro gel before bonding can significantly increase the bond strength of composite and resin modified glass ionomer to bleached enamel.