title: Apatite formation in composites of alpha-TCP and degradable polyesters.
abstract: The objective of this study was to investigate the conversion of alpha-Ca3(PO4)2 (alpha-TCP) in composite bone cements based on a water-degradable polyester matrix as a function of the polymer formulation and the alpha-TCP filler content. Cross-linkable dimethacrylates of epsilon-caprolactone/ D,L-lactide co-polymer or of epsilon-caprolactone/glycolide co-polymer were mixed with hydroxyethylmethacrylate, a photo-initiator and alpha-TCP to obtain composites with a filler content of 80 or 40 wt% alpha-TCP. The disk shaped composite samples were set by visible light irradiation and immersed in HEPES at 37 degrees C. At selected times the samples were removed from the solution and analysed with X-ray diffractometry and infrared spectroscopy. Conversion of alpha-TCP into calcium-deficient hydroxyapatite (CDHAp) was observed for all composites, but the reaction was not completed after 8 weeks immersion. The conversion rate of alpha-TCP and the crystallinity of the formed apatite apparently were not affected by the type of polyester used, but significantly depended on the alpha-TCP content of the composites. An increase of the amount of alpha-TCP in the composite resulted in a slower formation of CDHAp with a higher crystallinity.
authors.affiliation: Department of Dental Materials Science, Ghent University, De Pintelaan 185 (P8), B-9000 Ghent, Belgium.
authors.forename: Natasja M F
authors.initials: NM
authors.lastname: Van Den Vreken
authors.forename: Ilse Y
authors.initials: IY
authors.lastname: Pieters
authors.forename: Erna A P
authors.initials: EA
authors.lastname: De Maeyer
authors.forename: Geert J
authors.initials: GJ
authors.lastname: Jackers
authors.forename: Etienne H
authors.initials: EH
authors.lastname: Schacht
authors.forename: Ronald M H
authors.initials: RM
authors.lastname: Verbeeck
mesh_terms: D001031:Apatites / Q000138:chemical synthesis* / Q000737:chemistry; D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000737:chemistry; D001843:Bone Cements / Q000138:chemical synthesis* / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry*; D002208:Caproates / Q000737:chemistry; D017886:Durapatite / Q000138:chemical synthesis* / Q000737:chemistry; D007783:Lactones / Q000737:chemistry; D011091:Polyesters / Q000737:chemistry; D011100:Polyglycolic Acid / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D014961:X-Ray Diffraction
chemical_list: D001031:Apatites; D001672:Biocompatible Materials; D001843:Bone Cements; D002130:Calcium Phosphates; D002208:Caproates; D007783:Lactones; D011091:Polyesters; C485828:alpha-tricalcium phosphate; D011100:Polyglycolic Acid; C033616:poly(lactide); C121056:caprolactone; D017886:Durapatite