| Popis: |
β-tricalcium phosphate (β-TCP) based cement features unique biodegradability and mild temperature rise as a material for bone reconstruction. However, the bone cement often raises a shelf life issue and therefore study was made focusing on the temperature and humidity during storage. With the increase of storing days, the density and compressive strength of hardened cement were found to drastically decrease for the cement powder stored in a mixed state. In addition, the setting property was finally lost at the same time. Such a degradation was more evident at higher temperature and was the result of the formation of dicalcium phosphate anhydrous (DCP) instead of dicalcium phosphate dehydrate (DCPD) during the storage. On the contrary, for the cement stored in an unmixed state, very slight changes were detected in density, compressive strength and setting time with the increase of storing days even if the powders were kept in a humid environment. In the unmixed ones, DCP was not precipitated regardless of the storing temperature. Discussion was made on the condition for precipitating either DCPD or DCP in terms of the amount of water supplied during setting. Practically the work suggested that the β-TCP based cement needs to be conserved at lower temperature and in dry environment as possible to effectively increase the shelf life. |
