Biphasic calcium phosphates: Influence of three synthesis parameters on the HA/beta-TCP ratio

Hydroxyapatite (HA) contents measurements were conducted on eight biphasic calcium phosphate (BCP) samples obtained by sintering calcium-deficient apa tite formed previously by hydrolyzing a dicalcium phosphate dihydrate (DCPD ) powder. We evaluated the influences and interactions of three synthesis f actors: alkalinity, process duration, and concentration of the water suspen sion in DCPD. Those parameters were varied simultaneously between two limit levels. Experiments used a factorial design method (FDM) allowing optimiza tion of the number of samples as well as statistical analysis of results. F DM showed that HA content, in a defined experimental area, can be described by a first-order polynomial equation in which the initial alcalinity and t he DCPD/water ratio are the major influences. Experiment prove that pH meas ured at the end of the hydrolysis was predictive of the HA content in the f inal BCP. This study leads up to an isoresponse line diagram which will all ow the synthesis of some BCP with fitted HA/beta-tricalcium phosphate ratio s. (C) 2000 John Wiley & Sons, Inc.