Effects of bleaching agents on the surface microhardness and surface morphology of calcium silicate-based cements: An in vitro study

Purpose: To assess the effects of exposure to sodium perborate, carbamide peroxide, and hydrogen peroxide on the surface microhardness and surface morphology of ProRoot MTA and Biodentine.
Methods: A total of 50 specimens of each cement, ProRoot MTA and Biodentine, were prepared. The specimens were assigned into 5 groups based on the bleaching agent applied (n=10): A mixture of sodium perborate and distilled water (SP-DW), a mixture of sodium perborate and 3% hydrogen peroxide (SP-HP), carbamide peroxide (CP), hydrogen peroxide (HP), and control group. Bleaching agents were changed four times on every fourth day. Surface microhardness and surface morphology were assessed using a microhardness tester and scanning electron microscope, respectively. Data were analysed using two-way ANOVA and Tukey’s test.
Results: All bleaching agents caused morphological differences on the surfaces of the both cements. All bleaching agents, except SP-DW, caused a decrease in the microhardness of both cements, with HP causing the greatest decrease, followed by CP and SP-HP, respectively. Biodentine showed higher surface microhardness values than ProRoot MTA in all groups.
Conclusion: Biodentine may be recommended as a cervical barrier and a mixture of sodium perborate and distilled water may be the safest bleaching agent to preserve the surface properties of CSCs.

Keywords: Bleaching agents, calcium silicate-based cements, microhardness, surface morphology.