effect of bleaching with 15% carbamide peroxide on flexural strength of three resin-based restorative materials

Objectives: considering the increasing use of vital bleaching procedures and the increased application of newly introduced resin-based materials for tooth restoration, this study was designed to evaluate the effect of 15% carbamide peroxide gel on the flexural strength of three resin-based restorative materials. materials and methods: three different types of restorative materials namely beautifil ii giomer, cention n, and z250 micro-hybrid composite resin were evaluated in this in vitro, experimental study. twenty-four bar-shaped specimens were prepared from each restorative material, totaling 72 specimens, and were randomly assigned to two subgroups with and without bleaching procedure (n=12). in the bleaching subgroups, 15% carbamide peroxide gel was applied on the specimen surface 8 h a day for 14 days. the flexural strength of the specimens was then measured. two-way anova was used to compare the flexural strength of the specimens. results: there was a significant reduction in the flexural strength of materials following exposure to the bleaching agent (p<0.05). the flexural strength was significantly higher in the groups that did not undergo bleaching. however, the mean flexural strength of the restorative materials was not significantly different (p=0.12). conclusion: the flexural strength of beautifil ii giomer, cention n, and z250 micro-hybrid composite resin could be compromised subsequent to bleaching with 15% carbamide peroxide gel. the three resin-based restorative materials exhibited similar flexural strength values irrespective of the use or no use of 15% carbamide peroxide gel.