The effect of 15% carbamide peroxide gel on colour stability surface topography of giomer and microfill composite

Abstract

The use of tooth bleaching agents is on the rise at present. It is obvious that an important aspect of such materials to be evaluated is their effect on color stability of tooth-colored restorative materials and the possible color changes in such materials. In the present study, the effect of 15% carbamide peroxide on color stability and surface texture of a giomer and a microfill composite resin was evaluated in vitro. Materials and Methods. A total of 40 discs measuring 10 mm in diameter and 2 mm in thickness were prepared from a giomer and a microfill composite resin. Each material yielded 20 discs with completely smooth surfaces. Then a sprectrophotometer was used to measure a, b and l indexes of all the discs. Subsequently, the specimens were subjected to 15% carbamide peroxide bleaching gel. After measuring the color indexes once again, color changes (E) were calculated by the CIELAB system. Four specimens from each material (two specimens before bleaching agent application and one specimen after it) were viewed under an atomic force microscope (AFM) for surface texture evaluation. Mann-Whitney U test was used to compare color stability between the two groups. Statistical significance was defined at p<0.05. Results. Color changes (E) were not statistically significant in any of the two materials under study (p=0.13). In addition, no significant differences were detected in surface texture between composite resin and giomer before and after bleaching (p=0.59 and p=0.40, respectively). However, in both materials the differences in surface microhardness were significant before and after bleaching procedures (p<0.001). Conclusion. Based on the results of the present study, it was concluded that 15% carbamide peroxide did not induce clinically detectable color changes in composite resin and giomer despite increasing surface roughness.