Effect of Hydrogen Peroxide on Microhardness of Nanocmposites and Nanohybrid Composites

Abstract

Background and Aim: The purpose of this study was to evaluate the effect of hydrogen peroxide 40%  on microhardness of nanocmposites and nanohybrid composites.

Materials and Methods: 60 cylindrical discs of 3 nanocomposite and nanohybrid composite resins were fabricated. (Grandio/ Voco , Filtek  z350 /3M ESPE, Vitra/ FGM), 20 specimens of each (n=20), Each group was divided into 2 subgroups (n=10) (hydrogen peroxide 40% , control group). The specimens of the first group were immersed in hydrogen peroxide 40% for 45 minutes once a week. While the second group were stored in distilled water. After 14 days, microhardness was calculated using GALILEO MICROSCAN OD. Results were statistically analyzed by one-way ANOVA, Bonferroni, and T-tests at significance level of (p<0.05).

Results: No significant differences in microhardness were observed between hydrogen peroxide 40% and control group in 3M (p>0.05). However, significant differences in microhardness were detected in hydrogen peroxide 40% compared to control group in both VOCO and FGM. When composite resins were compared, statistically significant differences in microhardness were observed  in both hydrogen peroxide 40% and control group (p<0.05).

Conclusion: The effect of hydrogen peroxide 40% on composite resins was material dependent. Microhardness of 3M was not affected, while VOCO showed an increase in microhardness after bleaching.  A reduction in microhardness was observed in FGM after application of hydrogen peroxide 40% .