title: Effect of amorphous phases during the hydraulic conversion of α-TCP into calcium-deficient hydroxyapatite.
abstract: Powders of α-tricalcium phosphate (α-TCP), which readily react with water to form calcium-deficient hydroxyapatite (CDHA), are frequently used in bone cements. As, for clinical applications, it is important to adjust the setting reaction of the cements to a reasonable reaction time, exact knowledge of the hydration mechanism is essential. It is known that prolonged milling results in partial amorphization of α-TCP powders and that dissolution of the amorphous phase significantly accelerates the hydration, but it is not clear yet when the amorphous phase reacts in comparison to the crystalline α-TCP. Therefore the aim of this study was to investigate the development of quantitative phase content of α-TCP samples during hydration. For this purpose, three α-TCP powders, containing 0, 16 and 71wt.% of amorphous phase (ATCP), were mixed with either deionized water or a 0.1M Na2HPO4 aqueous solution. The crystalline evolution of the paste was assessed quantitatively during the first 48h of hydration at 23°C by G-factor quantification. The present investigations demonstrate that ATCP reacted earlier than crystalline α-TCP. The results also suggest the formation of an X-ray amorphous phase during the hydraulic conversion formation of α-TCP into CDHA.
authors.affiliation: GeoZentrum Nordbayern - Mineralogy, Friedrich-Alexander-University of Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany. Electronic address: katrin.hurle@fau.de.
authors.forename: Katrin
authors.initials: K
authors.lastname: Hurle
authors.affiliation: GeoZentrum Nordbayern - Mineralogy, Friedrich-Alexander-University of Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany.
authors.forename: Juergen
authors.initials: J
authors.lastname: Neubauer
authors.affiliation: RMS Foundation, Bischmattstrasse 12, CH-2544 Bettlach, Switzerland.
authors.forename: Marc
authors.initials: M
authors.lastname: Bohner
authors.affiliation: RMS Foundation, Bischmattstrasse 12, CH-2544 Bettlach, Switzerland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Doebelin
authors.affiliation: GeoZentrum Nordbayern - Mineralogy, Friedrich-Alexander-University of Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany.
authors.forename: Friedlinde
authors.initials: F
authors.lastname: Goetz-Neunhoeffer
mesh_terms: D016880:Anisotropy; D002118:Calcium / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry*; D010316:Particle Size; D011208:Powders; D012996:Solutions; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D011208:Powders; D012996:Solutions; C485828:alpha-tricalcium phosphate; D014867:Water; D017886:Durapatite; D002118:Calcium
keywords: Amorphization; Bone substitute; CDHA; Calcium phosphate cement; Quantitative in situ XRD