Journal of Dental Research, Vol 76, 905-912, Copyright © 1997 by International & American Associations for Dental Research Online Journals

ARTICLES

Setting reaction and hardening of an apatitic calcium phosphate cement

M. P. Ginebra, E. Fernandez, E. A. De Maeyer, R. M. Verbeeck, M. G. Boltong, J. Ginebra, F. C. Driessens and J. A. Planell
Department of Materials Science and Metallurgy, ETSEIB, Universitat Politecnica de Catalunya, Barcelona, Spain.

The combination of self-setting and biocompatibility makes calcium phosphate cements potentially useful materials for a variety of dental applications. The objective of this study was to investigate the setting and hardening mechanisms of a cement-type reaction leading to the formation of calcium-deficient hydroxyapatite at low temperature. Reactants used were alpha-tricalcium phosphate containing 17 wt% beta-tricalcium phosphate, and 2 wt% of precipitated hydroxyapatite as solid phase and an aqueous solution 2.5 wt% of disodium hydrogen phosphate as liquid phase. The transformation of the mixture was stopped at selected times by a freeze-drying techniques, so that the cement properties at various stages could be studied by means of x-ray diffraction, infrared spectroscopy, and scanning electron microscopy. Also, the compressive strength of the cement was measured as a function of time. The results showed that: (1) the cement setting was the result of the alpha-tricalcium phosphate hydrolysis, giving as a product calcium-deficient hydroxyapatite, while beta-tricalcium phosphate did not participate in the reaction; (2) the extent of conversion of alpha-TCP was nearly 80% after 24 hr; (3) both the extent of conversion and the compressive strength increased initially linearly with time, subsequently reaching a saturation level, with a strong correlation observed between them, indicating that the microstructural changes taking place as the setting reaction proceeded were responsible for the mechanical behavior of the cement; and (4) the microstructure of the set cement consisted of clusters of big plates with radial or parallel orientations in a matrix of small plate-like crystals.

This article has been cited by other articles:

				H.H.K. Xu, J.B. Quinn, S. Takagi, and L.C. Chow Processing and Properties of Strong and Non-rigid Calcium Phosphate Cement J. Dent. Res., March 1, 2002; 81(3): 219 - 224. [Abstract] [Full Text] [PDF]