In Vitro Evaluation of Shear Bond Strength of Sapphire Brackets after Dental Bleaching

Abstract

Background: The present study was conducted to evaluate the effects of different bleaching methods on the shearbond strength of orthodontic Sapphire brackets bonded to human premolars teeth using light cured composite resinand to determine the predominant site of bond failure.Materials and Methods: Thirty freshly extracted human premolars were selected and randomly divided into threegroups (10 per group). These groups are: control (unbleached) group, hydrogen peroxide group (HP) 37.5% ; which isthe in- office bleaching method group, carbamide peroxide group (CP) 16%; which is the at- home bleachingmethod group. After bleaching process was performed, all the teeth stored in distilled water in a sealed container atroom temperature for 24 hours before bonding was initiated, then orthodontic brackets were bonded with a lightcure composite resin, stored in distilled water at room temperature for another 24 hours before debonding then thebrackets de-bonded and tested for shear bond strength using an Instron universal testing machine. For adhesiveremnant index (ARI) the enamel surface and bracket base of each tooth were inspected under magnifying lens(20X) of a stereomicroscope.Results and Conclusions: Non-statistically significant differences of shear bond strengths were found between thecontrol group and the bleached groups, the dental bleaching in both methods did not affect the SBS of Sapphirebrackets. The mode of failure was mostly between the adhesive and the enamel and the bond failure between thebracket base and the adhesive were also observed