| Description |
The purpose of this study is to acquire a better understanding of the setting mechanism of self-setting hydroxyapatite cement through three research phases. In the first phase dissolution kinetic studies are conducted for three essential components of the self-setting hydroxyapatite cement system, Dical (dicalcium phosphate), TTCP (tetracalcium phosphate), and hydroxyapatite (HAP). Initial dissolution rate (IDR) data obtained from rotating disk experiments allows apparent solubilities (Cs) and dissolution rate constants (k) to be calculated. Apparent solubility calculations are further examined by slurry density experiments. The effect of particle size on apparent solubilities is also investigated in this study. The following are important findings: 1) HAP has the lowest Cs and k values among the three components, 2) TTCP dissolves considerably faster than Dical, 3) the Cs for Dical strongly depends on the particle size of the Dical powder. Results indicate that both HAP precipitation and Dical dissolution are rate limiting steps in this system. Also, the fast dissolution of TICP versus the slow dissolution of Dical significantly alters the Ca/P ratio of the liquid phase and affects the cement setting process. |
