Effects of bleaching agents on the microhardness and surface roughness of bulk fill composites

Aim: The aim was to compare the effect of 10 and 20% carbamide peroxide (CP) on microhardness (MHN) and surface roughness of two commercially available bulk fill composites (X-tra fill Bulk Fill and Tetric EvoCeram Bulk Fill). Materials and methods: A total of 50 specimens with both type composites were prepared using brass molds of inner diameter 10 mm and a height of 4 mm. Each type of composite was further divided into three groups, control group stored in artificial saliva for 14 days, other groups bleached with 10 and 20% CP respectively, for 14 days. Microhardness of the composite resin was tested with a Vickers hardness tester, whereas surface roughness was tested with profilometer. Results: All the analysis was performed using Statistical Package for the Social Sciences version 18. The value of p < 0.05 was considered statistically significant. Both 10 and 20% CP significantly reduced MHN of experimental composite resins. However, the mean surface roughness was significantly higher in X-tra fill Bulk Fill than Tetric EvoCeram Bulk Fill at 20% CP concentration. The mean MHN of Tetric EvoCeram was reduced when compared with X-tra fill at 20% CP. Conclusion: There was a significant reduction in the MHN of restorative materials observed after exposure to CP under a clinically simulated bleaching regimen. However, increase in surface roughness was seen only at 20% CP. Clinical significance: The physical properties, such as MHN and surface roughness have a crucial effect on the longevity of restorations and, moreover, on the esthetic demands of patients, but they may be compromised by bleaching treatments. The aim of this research paper was to assess the reaction of home bleaching agents on the physical properties of two Bulk Fill composite resin restorative materials.