Effects of Two Different Bleaching Agents on the Microhardness of Composite

Abstract

Background: Various bleaching agents are used in different concentrations to overcome discoloration of teeth. The oxidizing nature of these bleaching agents can cause replacement of composite due to their negative physical and mechanical properties. The objective of this study was to check the effects of 16% Carbamide Peroxide and 35% Hydrogen Peroxide on the microhardness of composites.

Methods: Nanofiller composite and micro hybrid composite was used to prepare 30-disc specimens. The specimens were randomly divided into 6 groups of n=05 specimens only and there was no subdivision. The initial and final surface microhardness test of both composites was carried out before and after treatment of specimens with bleaching agents using a Microhardness Testing Machine. The values were noted as the final Vickers Hardness number value of individual specimen. All data were collected and analyzed by using SPSS and p-value of < 0.05 was considered statistically significant. ANOVA was used to determine microhardness values in the groups for comparison.

Results: There was a significant reduction in microhardness of micro hybrid composite (p< 0.001) after bleaching with 35% Hydrogen peroxide, but a little reduction was found in nanofiller composite (p=0.001). The slight reduction in hardness was also observed with micro hybrid composite after treatment with 16% Carbamide Peroxide (p=0.003), but no reduction was found in nanofiller composite (p=0.110). There was significant difference (p=0.068) between Nanofiller 16% and micro hybrid 35%.

Conclusion: Hydrogen peroxide (35%) showed a greater reduction in microhardness of composites compared to 16% Carbamide peroxide.

Keywords: Resin Composite; Microhardness; Bleaching Agents; Discoloration; Concentrations; Tooth Colored Restorations.