Effect of postoperative bleaching on marginal leakage of resin composite and resin-modified glass ionomer restorations at different delayed periods of exposure to carbamide peroxide.

AIM To evaluate the effect of dental bleaching with carbamide peroxide at different exposure times on the microleakage of resin composite and resin-modified glass ionomer restorations after placement in extracted human teeth. METHODS AND MATERIALS 120 Class V cavity preparations were placed at the cementoenamel junction (CEJ) of human teeth. Half of the cavities were restored with Filtek P60 resin composite (C) and the other half were restored with Fuji II LC resin-modified glass ionomer (G). Each group was randomly divided into four subgroups (n=15). Groups C1 and G1 were not bleached and stored in artificial saliva at 37 degrees C to serve as control groups, while in Groups C2 and G2, C3 and G3, and C4 and G4 specimens were exposed to a 15% carbamide peroxide gel for one day, one week, and two weeks, respectively, following the placement of restorations. Microleakage was assessed using the dye penetration method. Data were analyzed using the Kruskal-Wallis and Wilcoxon tests (p=0.05). RESULTS The Kruskal-Wallis test showed no significant difference among all groups of composite or glass ionomer restorations with either enamel or dentinal margins with regard to microleakage (p>0.05). The Wilcoxon test revealed more marginal leakage in the enamel/glass ionomer margins than the enamel/composite margins (p<0.05). In comparisons within each group, the Wilcoxon test showed there was more microleakage in dentinal margins of composite restorations than in the enamel margins in the test groups (p<0.05). The dentinal margins of the glass ionomer in control groups showed more leakage than the enamel margins, but after the bleaching procedure all experimental groups showed statistically similar microleakage in both the enamel and dentinal margins (p>0.05). CONCLUSION Postoperative bleaching with carbamide peroxide could increase microleakage in the dentinal margins of composite and the enamel margins of resin-modified glass ionomer restorations. CLINICAL SIGNIFICANCE Rebonding of resin composite restorations should be considered following bleaching with 15% carbamide peroxide in order to reseal the margins. Resin-modified glass ionomer is not suitable as a filling material before bleaching because of its susceptibility to increased microleakage.