| Objective: In order to evaluate the effect of Beyond whitening system on human enamel surface, an in vitro study was undertaken to observe the changes in Microhardness and surface morphology. Methods:Twenty two intact, non-carious, human teeth extracted in recent three months for orthodontic reasons were used in this experi-ment.All the teeth were stored in distilled water at room temperature from extraction to preparation for the experiment. In order to control for individual variation in enamel-surface characteristics among tested teeth, each tooth crown was sectioned into buccal and lingual sides after removing the root.One side was used for treatment of Beyond whitening system , the other as an untreated control.Twenty specimens from each group were measured for Vicker's microhardness of the enamel. The enamel morphology of two remained specimens each group were imaged and analyzed using an environmental scanning electron microscopy . Results:1. Vicker's microhardness test: Immediately after the bleaching procedure, seven specimens'Vicker's values increased, whereas other thirteen specimens'Vicker's values decreased in treatment group . Bleaching treatment resulted in a nonsignificant reduction in microhardness values when compared with values of the nontreated specimens of the control group(experiment 292.4 ±43.7 , control 299.7 ±4.5).Analysis of two paired sample t-test showed no statistically significant difference between the bleaching group and the untreated control group(P>0.05). 2 .Enviromental scanning electron microscopy: The surface porosity of enamel increased slightly and enamel liquated in some regions in the experimental group compared to the control group. Conlusions:1. Results showed Beyond whitening system did not signifi-cantly affect the enamel microhardness. 2. Even though bleaching agent caused mild ,locational alterations in the surface morphology of enamel,but these alterations were likely not clinically significant. |
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