title: Conversion of octacalcium phosphate in calcium phosphate cements.
abstract: This study investigated the in vitro conversion reaction in calcium phosphate cements (CPCs) containing octacalcium phosphate (OCP) as one of the reagents. OCP is known to be a precursor for apatite formation in vivo. The reaction products were characterized using infrared spectroscopy and X-ray diffraction. Although the conversion of OCP into hydroxyapatite is thermodynamically favorable, OCP only yields apatite formation in CPC provided it is combined with a highly soluble Ca(2+) and OH(-) releasing reaction partner. In this respect, tetracalcium phosphate is a promising compound. Adding small amounts of monocalcium phosphate monohydrate can stimulate the setting through intermediate brushite formation. The preparation method of OCP might drastically affect the performance of the cement. The reaction path of the setting of these CPC probably does not conform to the singular point principle described in the literature, and an in situ hydrolysis of OCP to apatite is conceivable. Simulation of apatite formation using OCP as the precursor and/or seed in CPC might be beneficial for some biomedical applications.
authors.affiliation: Department of Dental Materials Science, Institute for Biomedical Technologies (IBITECH), Ghent University, De Pintelaan 185 (P8), B-9000 Gent, Belgium.
authors.forename: E A
authors.initials: EA
authors.lastname: De Maeyer
authors.forename: R M
authors.initials: RM
authors.lastname: Verbeeck
authors.forename: C W
authors.initials: CW
authors.lastname: Vercruysse
mesh_terms: D001843:Bone Cements / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous