title: Morphological and phase characterizations of retrieved calcium phosphate cement implants.
abstract: A self-hardening calcium phosphate cement (CPC), consisting of equimolar amounts of tetracalcium phosphate and dicalcium phosphate anhydrous, hardens when mixed with water and forms a resorbable hydroxyapatite (HA) as the end-product. The objective of this study was to investigate the changes of the phase and morphology of the CPC during hardening and aging under in vivo conditions. CPC samples retrieved 12 h after hardening in vivo had already contained carbonated HA (type B), even though the initial cement mixture did not contain carbonate as one of the solid components. The mass fraction of carbonate in the 12-h sample was about 1%. The results suggested that under in vivo conditions carbonate is readily available and this allows formation of carbonated HA in favor of carbonate-free HA. The carbonate content of the CPC samples retrieved 3 months after implantation was similar to that of the 12-h samples, and the exterior surfaces of the 3-month samples appeared less crystalline than that of the 12-h samples.
authors.affiliation: American Dental Association Health Foundation, Paffenbarger Research Center, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. shozo.takagi@nist.gov
authors.forename: S
authors.initials: S
authors.lastname: Takagi
authors.forename: L C
authors.initials: LC
authors.lastname: Chow
authors.forename: M
authors.initials: M
authors.lastname: Markovic
authors.forename: C D
authors.initials: CD
authors.lastname: Friedman
authors.forename: P D
authors.initials: PD
authors.lastname: Costantino
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001843:Bone Cements / Q000737:chemistry*; D018786:Bone Substitutes / Q000737:chemistry*; D002119:Calcium Carbonate / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry*; D008297:Male; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011184:Postoperative Period; D019736:Prostheses and Implants; D051381:Rats; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D001843:Bone Cements; D018786:Bone Substitutes; D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; D017886:Durapatite; C020243:calcium phosphate; D002119:Calcium Carbonate; C485829:calcium phosphate, dibasic, anhydrous