The effect of anti-oxidant agents as neutralizers of bleaching agents on dentin bond strength

Abstract

Background: Reduction in bond strength when bonding was done immediately after intracoronal bleachingprocedure has been recognized. The purpose of this study is to assess the effect of antioxidants (10% sodiumascorbate (SA), 0.1M thiourea and7% sodium bicarbonate (SB)) on reversing bonding strength of compositeresin to bleached dentin.Materials and method: Sixty upper 1st premolar teeth, were selected, the crowns of the teeth were embedded inacrylic resin blocks exposing a flat dentin from the buccal surface, then divided into 6 groups (10 sampleseach). Bleaching for the experimental groups was performed using 35% hydrogen peroxide bleaching gel(pola–office).Group A (Negative control group; dentin samples immediately bonded with composite withoutbleaching)Group B (Positive control group; dentin samples bleached and immediately bonded with composite).Group C (Dentin samples bleached and stored for 14 days in DDW then bonded with composite). Group D (Dentinsamples bleached and treated with 10% (SA) then immediately bonded with composite). Group E (Dentin samplesbleached and treated with 0.1M thiourea then immediately bonded with composite). Group F (Dentin samplesbleached and treated with 7% SB then immediately bonded with composite).The shear bond strength wasdetermine using instron testing machine.Results: Bleaching the dentin with 35 % hydrogen peroxide gel for 24 minutes resulted in reduction in bondstrength of the bleached teeth when bonding was performed immediately after bleaching. Delayedbonding of composite to the bleached dentin for 14 days will result in a highly significant increase in theshear bond strength.Conclusion: Treating the bleached dentin with 10% (SA) in water base showed a highly significant increase inthe shear bond strength of the composite to dentin and reversing the bond strength value to the level of theunbleached dentin. Treating the bleached dentin with 0.1M thiourea significantly increased the shear bondstrength of the composite to dentin