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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 3 (1992), S. 79-83 
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Glass-ceramic A-W containing crystalline apatite and wollastonite in an MgO-CaO-SiO2 glassy matrix bonds to living bone through an apatite layer which is formed on its surface in the body. The parent glass G of glass-ceramic A-W and glass-ceramic A, which has the same composition as glass-ceramic A-W but contains only the apatite, also bond to living bone through the surface apatite layer, whereas glass-ceramic A-W(Al), which contains the apatite and wollastonite in an MgO-CaO-SiO2-Al2O3 glassy matrix, neither forms the surface apatite layer nor bonds to living bone. In the present study, in order to reveal the mechanism of formation of the surface apatite layer, changes in ion concentrations of a simulated body fluid with immersion of these four kinds of glass and glass-ceramics were investigated. Bioactive glass G and glass-ceramics A and A-W all showed appreciable increases in Ca and Si concentrations, accompanied by an appreciable decrease in P concentration, whereas non-bioactive glass-ceramic A-W(Al) hardly showed any element concentration change. It was speculated from these results that dissolution of the Ca(II) and Si(IV) ions from bioactive glass and glass-ceramics plays an important role in forming the apatite layer on their surfaces in the body.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 4 (1993), S. 1-4 
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Non-bioactive glass-ceramic A-W(Al) containing apatite and wollastonite in a MgO−CaO−SiO2−Al2O3 glassy matrix did not form an apatite layer on its surface in a simulated body fluid with ion concentrations nearly equal to those of human blood plasma and also in the fluids with small amounts of the calcium and silicate ions added individually, but formed the apatite layer in the fluid with the calcium and silicate ions added simultaneously. This indicates that the calcium and silicate ions dissolved from bioactive glass-ceramic A-W containing the apatite and wollastonite in a MgO−CaO−SiO2 glassy matrix play a cooperative and important role in forming an apatite layer on its surface in the body, to give the glass-ceramic bioactivity. The calcium ion might increase the degree of the supersaturation of the surrounding body fluid, and the silicate ion might provide favourable sites for nucleation of the apatite on the surfaces of glass-ceramic.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 25 (1991), S. 1363-1370 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Previous studies on surface structural changes in vitro as well as in vivo of bioactive A-W-type glass-ceramics and Bioglass-type glasses showed that the essential condition for glasses and glassceramics to bond to living bone is formation of a bonelike apatite layer on their surfaces in the body. Gross et al., however, had explained the bone-bonding mechanism of Ceravital-type apatitecontaining glass-ceramic without mentioning formation of the surface apatite layer. In the present study, apatite formation on the surface of one of Ceravitaltype glass-ceramics was investigated in vitro as well as in vivo. An apatitecontaining glass-ceramic of the composition Na2O 5, CaO 33, SiO2 46, Ca(PO3)2 16 wt%, which was named KGS by Gross et al., was soaked in an acellular simulated body fluid which had ion concentrations almost equal to those of the human blood plasma. The same kind of glassceramic was implanted into a rabbit tibia. Thin-film x-ray diffraction, Fourier transform infrared reflection spectroscopy, and scanning electron microscopic observation of the surfaces of the specimens soaked in the simulated body fluid showed that Ceravital-type glass-ceramic also forms a layer of carbonate-containing hydroxyapatite of small crystallites and/or a defective structure on its surface in the fluid. Electron probe x-ray microanalysis of the interface between the glassceramic and the surrounding bone showed that a thin layer rich in Ca and P is present at the interface. These findings indicated that Ceravital-type glassceramics also form the bonelike apatite layer on its surface in the body and bond to living bone through the apatite layer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 721-734 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: High-strength bioactive glass-ceramic A-W was soaked in various acellular aqueous solutions different in ion concentrations and pH. After soaking for 7 and 30 days, surface structural changes of the glassceramic were investigated by means of Fourier transform infrared reflection spectroscopy, thin-film x-ray diffraction, and scanning electronmicroscopic observation, in comparison with in vivo surface structural changes. So-called Tris buffer solution, pure water buffered with trishydroxymethyl-aminomethane, which had been used by various workers as a “simulated body fluid,” did not reproduce the in vivo surface structural changes, i.e., apatite formation on the surface. A solution, ion concentrations and pH of which are almost equal to those of the human blood plasma - i.e., Na+ 142.0, K+ 5.0, Mg2+ 1.5, Ca2+ 2.5, Cl- 148.8, HCO3- 4.2 and PO42- 1.0 mM and buffered at pH 7.25 with the trishydroxymethylaminomethane-most precisely reproduced in vivo surface structure change. This shows that careful selection of simulated body fluid is required for in vitro experiments. The results also support the concept that the apatite phase on the surface of glass-ceramic A-W is formed by a chemical reaction of the glass-ceramic with the Ca2+, HPO42-, and OH- ions in the body fluid.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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