Hardened PCA/CPC cement with and without tartaric acid and/or stannous fluoride was subjected to X-ray analysis after storage in three kinds of solutions (artificial saliva-like solution, phosphate buffer solution, and distilled water) , and amount of calcium, phosphate and fluoride ions released into the storage solution was measured. In distilled water, calcium and phosphate ions were continuously released from not only the PCA/CPC cement with tartaric acid and stannous fluoride but also from the cement without these additives. However, in artificial saliva and phosphate buffer solutions, release ceased after about one month and uptake of both ions was detected. X-ray analysis revealed the formation of fluoroapatite and hydroxyapatite in the hardened cement containing tartaric acid and stannous fluoride when it had been stored in artificial saliva or distilled water.Conversely, in the cement without these additives, only minor amount of apatite formation was observed, even when it was stored in distilled water for 6months.In addition, it was observed that fluoride ions were continuously released from the cement containing stannous fluoride for 6months.