الفهرس 
Title : Effect of two different bleaching agents on human enamel surface q
ContentsOnly 14 pages are availabe for public view
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Abstract
This in-vitro study was designed to investigate bleaching with two different concentrations of hydrogen peroxide on human enamel surfaces concerning surface roughness and color stability. A total number of 60 specimens that were prepared from extracted human anterior teeth were used in this study. The selected teeth were sectioned horizontally at the level of the Cemento Enamel Junction mounted in acrylic resin blocks so that their labial surfaces were exposed for applications. The specimens were then randomly divided to two equal groups according to the bleaching agent; 30% hydrogen peroxide (GI) and 38% hydrogen peroxide (GII). After bleaching procedures were completed according to each manufacturer’s instructions, the specimens were evaluated for surface roughness and color measurements immediately. Each group was then divided into two subgroups according to the solution where it will be immersed as A referred to Cola, B referred to black tea and C referred to artificial saliva. Specimens were kept in an incubator at 37 degrees celcius and their color was evaluated at 24 and 48 hours. Mann-Whitney U test was used to compare between the two bleaching agents. Wilcoxon signed-rank test was used to study the changes in Ra after bleaching. Three-way ANOVA test was used to compare between the bleaching agents, storage media as well as immersion times. Tukey{u2019}s post-hoc test was used for pair-wise comparisons when ANOVA test is significant. The results showed a significant increase in surface roughness of the bleached samples compared to the baseline measurements. However, there was no significant difference between the samples of the two bleached groups concerning surface roughness