| Summary: | Abstract Background Three types of gypsum products were commonly used in dentistry to fabricate dental casts and dies which includes dental plaster, dental stone, and improved stone. Improved stone could be used as final casts and dies for building of final indirect dental restorations. Even though the cost of dental plaster is very low, their inherent lowest surface microhardness, compressive strength, and dimensional stability values confined their utilization as preliminary cast and die materials. This in vitro study was evaluated the effect of incorporation of 10 weight % (wt.%) aluminum oxide nanoparticle fillers on surface microhardness, compressive strength, and setting expansion of the dental plaster compared with the gold standard improved stone. Methods The control group was prepared by mixing dental plaster with water. The innovative reinforced dental plaster group was prepared by incorporation of 10 wt.% aluminum oxide nanoparticle fillers to the conventional one prior to water mixing. The improved stone group was prepared by mixing the improved stone with water. Chemical composition of the three group powders was determined using x-ray florescence spectrometer (XRF). The surface microhardness, compressive strength, and setting expansion were measured. Results The results revealed that innovative dental plaster reinforced by 10 wt.% aluminum oxide nanoparticle fillers was shown higher mean surface microhardness than that of conventional dental plaster, while higher mean compressive strength values than that of improved stones and conventional dental plaster. Moreover, reinforced dental plaster was shown lower mean setting expansion values compared with conventional dental plaster and improved stones (P value ≤ 0.05). Conclusion Within limitation of this study, the results are indicating the opportunity of the innovative reinforced dental plaster to be used alternatively to improved stone (type IV) for fabrication of final dental casts and dies.
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