Surface Changes of Completely Set CEM Cement after the Application of Bleaching Agents(cp,hp,sodium perborate,sodium perborate+hp): Scanning Electron Microscopy and an Energy-dispersive X-Ray Microanalysis

Abstract

Bleaching agents, as a chemical agent, might have detrimental effects on soft and hard tissues and the restorative materials in the oral cavity through oxidative mechanisms. The aim of the present study was to evaluate the element distribution and surface changes in completely set CEM cement after application of 35% carbamide peroxide, 40% hydrogen peroxide, sodium perborate and hydrogen peroxide30% + sodium perborate as commercial bleaching agents by an energy-dispersive x-ray microanalysis(EDX)system.The surface structure observed using the scanning electron microscope.Materials and methods: Twenty-five completely set CEM cement samples, measuring 4×4 mm2, were prepared in the present study in vitro and randomly divided into 4 groups based on the preparation technique as follows: the control group with no bleaching agent on the completely set CEM cement surface; 35% carbamide peroxide group, 3060 minutes 4 times; 40% hydrogen peroxide group, 1520 minutes 3 times; sodium pebrorate group, in which the powder and liquid were mixed and placed on the CEM cement surface 4 times and hydrogen peroxide + sodium perborate 4 times. The samples were evaluated under on electron microscope. Data were analyzed at a significance level of P<0.05.Results: EDX showed similar element distribution of oxygen, sodium, calcium and carbon in CEM cement with the use of carbamide peroxide and hydroxide peroxide; however, the distribution of silicon was different (P<0.05). In addition, these bleaching agents resulted in significantly higher levels of oxygen and carbon (P<0.05) and a lower level of calcium (P<0.05) compared to the control group. Sodium perborate gave rise to the highest levels of oxygen and sodium (P<0.05) and the lowest levels of calcium, carbon and silicon (P<0.05) compared to the other two bleaching agents. hydrogen peroxide + sodium perborate group has the same result as the sodium perborat group.Conclusion: The element distribution of completely set CEM cement under the influence of sodium perborate and hydrogen peroxide + sodium perborate was different from that under the influence of carbamide peroxide and hydrogen peroxide.