COMPARING THE EFFECT OF HOME BLEACHING AGENTS ON THE MARGINAL INTEGRITY AND BOND STABILITY BY TWO DIFFERENT BONDING SYSTEMS TO DIFFERENT COMPOSITE RESTORATIVE MATERIALS: AN IN VITRO STUDY

Abstract

Vital bleaching is now widely demanded by the public and ranks among the most frequent cosmetic treatments in dentistry. Effect of bleaching by carbamide peroxide on bond strength of microhybrid and nano hybrid restorative materials by two total and self-etch bonding systems to dentin has not been investigated intensively. This study aimed to examine the effect of  home bleaching using 20% carbamide peroxide on the shear bond strengths of different adhesives  systems to two different composite materials to enamel and dentin. Two hundred enamel and dentin disks were prepared from extracted third molars with the dimensions of 5x5x5mm. Samples are then randomly divided into eight groups with 25 samples in each for bonding purposes. Bonding procedures were completed with total and self-etch for each half of nano hybrid and micro hybrid composites. Half of the samples are then subjected to bleaching by 20% carbamide peroxide and other half left as control. Intra group comparison between the results of all four groups showed that total etch and self-etch bond strength on enamel and dentin decreases significantly in post bleach groups compared with control non bleached groups (P<0.05).Inter group comparisons between groups show that bond strengths are comparatively higher for etch and rinse groups than self-etch but the differences are statistically insignificant. Within the limits of current study, bleaching significantly reduced the adhesive bond of attached restorations to dental hard tissue.
Keywords: composite restorations, bleaching, carbamide peroxide, bond strength