Effect of Bleaching on Color Change and Refractive Index of Dental Composite Resins

Abstract

This study investigated the effects of three bleaching agents (Whiteness Perfect, Whiteness Super, and Whiteness HP) on the color change and refractive index of three dental composites (Admira, Durafill VS, and Gradia Direct). Twenty diskshaped specimens (10×2 mm) of each composite were prepared and divided into four subgroups (n=5). An unbleached group was used as a control, while the remaining specimens in the three subgroups were bleached with one of the bleaching agents respectively. Color change was assessed according to CIELAB color system and refractive indices were determined by phase modulated spectroscopic ellipsometry. Color differences between bleaching and baseline value (ΔE) were less than 3.3 for all groups. However, bleaching with Whiteness HP led to noticeable color changes for Admira and Durafill VS. While this agent had no effect on the refractive indices of these composites, the other two agents containing carbamide peroxide increased their refractive indices. Therefore, results suggested that replacement of such composite restorations may be required after bleaching.

Effects of Light Curing Modes and Resin Composites on Temperature Rise under Human Dentin: An in vitro Study

“…The other end was formed by an alkoxy group, resulting in an inorganic area, bonded to other monomers by a chemical reaction of condensation, converting the monomer precursors in a polymeric inorganic condensate -via sol-gel processing -to create a complex structure with the formation of the Si-O-Si chain in the inorganic area of the polymer [3][4][5]35) . The significantly greater temperature rise with the ormocer compared to the other products presumably resulted from the different monomer compositions, given the relatively low light transmittance of this product.…”

Effects of bleaching agent on physical and aesthetic properties of restorative materials

“…Li et al 13) recorded change in the color of nanohybrid composite after the bleaching with 15% carbamide peroxide, and similar changes were observed when using 35% hydrogen peroxide in microfilled composites. These changes can be attributed to the amount of resin and particle size 13,24) . Kamangar et al 36) concluded that bleaching with 15% carbamide peroxide and 40% hydrogen peroxide does not lead to the significant changes in color of nanohybrid and microhybrid composite materials which was similar to the results obtained in our study.…”

“…SEM microscopy showed that the use of 10-16% carbamide peroxide cause slight, but statistically significant increase in the surface roughness and porosity 22) . Applications of hydrogen and carbamide peroxide could lead to significant changes in color of composite materials, especially microfilled and nanofilled composites 23) , and these changes can be attributed to the volume of the organic matrix and filler type 24) . Hydrogen peroxide contributes to increased brightening of composite materials compared to carbamide peroxide of the same concentration 25) .…”

Effects of Bleaching Agents on the Microhardness and Surface Roughness of Bulk Fill Composites

“…The differences in the composite roughness and MHN values obtained after the same bleaching regime may be related to the different polymers in their organic matrix, and their filler content and particle size. 24,25 There is limited scientific evidence regarding the effect of bleaching solutions on MHN of restorative resins. 3,26,27 Along with oxidizing agent used in the at-home bleaching agents, an additive called carbopol (carboxy polymethylene) may be added to increase the viscosity of gel that in turn improves bonding to the enamel surface and prolongs the liberation of oxygen.…”