Research Paper (postgraduate) from the year 2010 in the subject Medicine - Dentistry, grade: none, University of Mosul, language: English, abstract: Aims: To evaluate the effect of different water types on the water powder ratio of dental gypsum products. Materials and Methods: In this study five types of water (distilled, tab, slurry, de-ionized and well water) were used to be mixed with two types of dental gypsum products (plaster and stone). Results: Results showed a statistically significant difference at p ≤ 0.05 in water powder ratio of gyp-sum products when mixed with different types of water that used in this study . Conclusions: Water requirement of gypsum product varies in respect to the type of water used to be mixed with. The most pronounce decrease in water requirement of dental gypsum products was achieved with slurry water.