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Aims: To evaluate the effect of three different cleanser on the color stability of three different types of artificial teeth. Materials and methods: sixty samples of artificial anterior teeth were prepared which are Acry-Rock, RMH teeth and Porcelain teeth and immersed in three types of denture cleanser(Bony plus, Protefix and soda+ vinegar) for 8 hours and the color of the teeth was measured by Easyshade's spectrophotometer at 3 intervals(1,2and4weeks). Results: Showed that the a'b values of ceramic teeth and L value of RHM teeth were significantly differencent after 2 week of immersion in three type of denture cleanser. Analysis of variance demonstrated that L'a'b value for ceramic teeth and RHN teeth were statistically significant after 4 week immersion in three type of denture cleanser, The result of color change (∆E) for three denture cleansers of three periods of immersion were clinically accepted. Conclusion: Long period of immersion of artificial teeth in denture cleanser cause significant color change for L*a*b* values but they were clinically accepted.

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Aims: The study aims to evaluate the effect of mixing techniques and water powder ratio on the compressive strength and surface hardness of dental stone. Materials and Methods: The samples of compressive strength and surface hardness testes were prepared by 2 water powder ratio the ratio recommended by manufacture and that used by dentists and 2 mixing methods rubber bowl and spatula and zip-lock bag. The collected data analyzed using one sample t-test, ANOVA and Duncans' multiple range test at p≥0.5. Results: The results showed statistically significant difference in compressive strength and surface hardness among tested groups. Conclusion: Mixing by rubber bowl and spatula and using water powder ratio recommended by manufacturer gives the highest compressive strength value while using zip-lock bag give a higher surface hardness value than rubber bowl and spatula.