α-Tricalcium phosphate: synthesis, properties and biomedical applications.

R G Carrodeguas, S De Aza

Instituto de Cerámica y Vidrio, CSIC, C/Kelsen, 5-28049 Madrid, Spain. rgc@icv.csic.es

Acta biomaterialia 2011 Oct

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Nowadays, α-tricalcium phosphate (α-TCP, α-Ca(3)(PO(4))(2)) is receiving growing attention as a raw material for several injectable hydraulic bone cements, biodegradable bioceramics and composites for bone repair. In the phase equilibrium diagram of the CaO-P(2)O(5) system, three polymorphs corresponding to the composition Ca(3)(PO(4))(2) are recognized: β-TCP, α-TCP and α'-TCP. α-TCP is formed by heating the low-temperature polymorph β-TCP or by thermal crystallization of amorphous precursors with the proper composition above the transformation temperature. The α-TCP phase may be retained at room temperature in a metastable state, and its range of stability is strongly influenced by ionic substitutions. It is as biocompatible as β-TCP, but more soluble, and hydrolyses rapidly to calcium-deficient hydroxyapatite, which makes α-TCP a useful component for preparing self-setting osteotransductive bone cements and biodegradable bioceramics and composites for bone repairing. The literature published on the synthesis and properties of α-TCP is sometimes contradictory, and therefore this article focuses on reviewing and critically discussing the synthetic methods and physicochemical and biological properties of α-TCP-based biomaterials (excluding α-TCP-based bone cements). Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.