Abstract
Gypsum products used in dentistry are in the form of α and β calcium sulfate hemihydrate as dental stone and plaster.The aim of the study is examination of the particle’s shape, size and distrib-ution of the different commercial dental gypsum products. The particle’s shape was examined microscopically with trans-mitted light microscope instead of ref-lected light microscope or electron micro-scope. Analysis of the particle’s size distribution and the measurement of the powder particle’s fineness was performed by sieving procedure using sieving machine. The data was collected and calculated and then compared with the ADA Specification No. 25 for gypsum products.The results showed that the micro-scopical examination with transmitted light microscope give clear accurate and precise image about the different shapes of the stone and plaster. The results of the analysis for particle’s size distribution showed that there is a difference in the distribution between the different tested commercial dental gypsum products and also showed that all products have par-ticle’s size larger than the ADA Speci-fication No. 25.
