The purpose of this study was to develop experimental paste − paste − type phosphate − bonded investments and evaluate their clinical use . Powders for Paste l comprised a 100 − g mixture of cristobalite ( 95 , 90 , 85 and 80g)and ammonium dihydrogen phosphate ( 5, 10 , 15 and 20 g) . These were mixed with colloidal silica liquid , diluted twice with water , anCl four kinds ( A − D )of paste were prepared . Paste 2 comprised magnesium oxiCle and vaseline , A commercial investment was a1so

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... as a contro1 , Fundamenta1 properties and the casting accuracy with surface roughness were examined , With an increase in ammonium dihydrogen phosphate, extension of the setting time , an increase in setting expansion , and a decrease of thermal expansion were noted 、 However , the compressive strength after firing was almost the same among experimental investments . The casting from Cshowed a small gap and suita1 )le surface , and the values were close to those obtained from the contro1 , These results suggest that experimental paste type −investments are applicahle for clinical use , and C was particularly