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Dicalcium phosphate dihydrate (DCPD) is the most widely-used dentifrice abrasive in non-therapeutic tooth-paste requiring, low abrasive level, high stability and excellent compatibility with other formulation ingredients. One of the difficulties encountered in the use of this material in tooth-paste is that unless storage of the product is maintained at a relative low temperature there is a distinct tendency to lose water of crystallization. Another difficulty which has been encountered is that there is a tendency for the product to become lumpy. Various means have been proposed for increasing the stability and overcoming the lumping tendency, most of which means comprise the addition of stabilizing agent. But there is not any report about the relationships between the mechanism of dehydration, physical properties, structure and manufacturing condition. In this experiment, DCPD were manufactured by methods of Moss' patent, its two varied and J.P.VIII, these were studied by means of stability test, IR spectra, and DTA. According to the manufacturing conditions, DCPD has different physical properties and structures, i. e., monoclinic system of low drying temperature, triclinic system of high drying temperature. Dehydration of DCPD may be supposed one step debydration at about $100^{\circ}$ 수식 이미지 and it finaly converts to ${\gamma}-pyrophosphate$ 수식 이미지 at about $465^{\circ}$ 수식 이미지 and if the drying temperature is high it becomes DCP anhydrous. DCPD made by Moss' patent is thought of the best polishing agent of tooth-paste.
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