title: In situ study on the curing process of calcium phosphate bone cement.
abstract: The aim of this study was to follow the entire curing process of modified alpha-TCP cement, and to explore how the liquid phase affects the curing reaction. Two calcium phosphate bone cements (CPCs) with a variety of aqueous solution were studied for comparison. In situ X-ray diffraction analysis and pH testing were employed to follow the chemical reaction, while quantitative ultrasonic measurement (QUS) was carried out to monitor the physical change. Results showed that CPC powders were completely consumed after 72 h. Two steps were presented in apatite formation. The first step was the precipitation of carbonated hydroxyapatite (CHA), and in the second step, conversion of calcium deficient hydroxyapatite (CDHA) was the dominant reaction. Finally, CPCs were fully converted to apatite except the cement with NaH2PO4 as liquid phase, because acidic environment inhibited the conversion of apatite. The pH increased linearly after mixing, when supersaturation was reached, it decreased to pH approximately 6.0 gradually. Ultrasound measurement indicated that the variation of speed of sound (SOS) was related to both apatite formation and microstructural evolution. Ultrasonic attenuation coefficient (UAC) was able to quantitatively describe the curing process from viscous paste to elastic solid as a function of curing time. Moreover, the curing reaction conformed to classical dissolution-precipitation mechanism.
authors.affiliation: Department of Materials Science and Engineering, Xiamen University, Xiamen 361005, China.
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Song
authors.forename: Zude
authors.initials: Z
authors.lastname: Feng
authors.forename: Ting
authors.initials: T
authors.lastname: Wang
mesh_terms: D001843:Bone Cements / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D019245:Compressive Strength; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013997:Time Factors; D014465:Ultrasonics
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; C020243:calcium phosphate