Abstract
Sodium hexametaphosphate (NaโHMP) is a common liquefying agent widely used in the ceramics industry for modifying the rheological behavior of ceramic slurries. The objective of this study was to investigate the influence of NaโHMP on several properties of calcium phosphate cements (CPCs). Various types of CPCs were prepared by mixing the same powder, namely, a mixture of tetracalcium phosphate and dicalcium phosphate anhydrate, with various liquids, namely, distilled water, Na~2~HPO~4~ solutions, and NaโHMP solutions. The setting time, mechanical strength, rheological properties, and injectability of the cement pastes were examined in this work. Also, Xโray diffractometry (XRD) and scanning electron microscopy (SEM) techniques were employed for phase analysis and morphological evaluations, respectively. The results showed that, compared to CPCs made with water and Na~2~HPO~4~ solutions, the CPC pastes made with NaโHMP solutions had improved stability and injectability but prolonged setting times. The XRD and SEM studies showed that NaโHMP inhibited the growth of apatite crystals during soaking of the cements in Ringer's solution. Thus, the CPC made with NaโHMP solution had lower compressive strength than those made with water or Na~2~HPO~4~ solutions. Although NaโHMP could improve the injectability and stability of the CPC paste, it impaired other basic properties of the cement. Thus, it is not an appropriate liquefier additive. ยฉ 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009