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  • 1
    Electronic Resource
    Electronic Resource
    Effect of bioactive glass granules and polytetrafluoroethylene membrane on repair of cortical bone defect (1995)
    Springer
    Journal of materials science 6 (1995), S. 639-641 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The effect of bioactive glass (BG) granules and nonresorbable polytetrafluoroethylene (PTFE) membrane on the repair of cortical bone defects was studied. Monocortical holes (diameter 3.0 mm) were drilled in rabbit tibia. Sixteen holes were filled with BG granules (diameter 630–800 μm). Twelve holes were left empty and covered with PTFE membrane. No material was used at ten control holes. All experiment areas were covered with periosteum attached to the soft tissue flap. Histomorphometric evaluation of resection specimens showed that new bone and glass particles formed a continuous bridge in the BG group at the upper part of the hole, occupying 73.6% and 61.7% of the defect at 6 and 12 weeks, respectively. If only the amount of bone but not glass particles was included in the measurements the corresponding figures were 31.4% and 41.5%. The bone repair in the PTFE group was 12.1% and 11.3% and in the control group 25.1% and 23.3% at 6 and 12 weeks, respectively. The results indicate that BG granules improve repair of cortical bone defects and PTFE membrane seems to impair bone formation in these defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00123444
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  • 2
    Electronic Resource
    Electronic Resource
    Bioactive double glass coatings for Co-Cr-Mo alloy (1995)
    Springer
    Journal of materials science 6 (1995), S. 242-247 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Glass compositions for double coatings for a Co-Cr-Mo alloy were developed. The glass compositions were chosen to fulfil such requirements as matching thermal expansion, low glass transition temperature and moderate solubility. For the ground coat a fairly high durability is required, whereas the cover coat must be bioactive, i.e. become attached to living bone by a chemical bond. Two compositions of each type were developed by computer-aided optimization. The glasses were chosen in the Na2O−CaO−B2O3−Al2O3−SiO2−P2O5 system. The bioactivity was tested in vitro by immersion in a simulated body fluid. The double coatings on Co−Cr−Mo alloy released hexavalent chromium into the solution as detected by yellow colouration and spectrophotometry. This colouration was strong at the margin between coated and uncoated metal and may be explained by oxidation of trivalent chromium of the alloy in the presence of glass. The released chromium did not have any notable effect on the calcium phosphate formation. After replensihing the solution no coloration was observed. This suggests that the chromate is easily dissolved and that it may be possible to wash it out prior to implantation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146863
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  • 3
    Electronic Resource
    Electronic Resource
    Bioactive glass granules and polytetrafluoroethylene membrane in the repair of bone defects adjacent to titanium and bioactive glass implants (1998)
    Springer
    Journal of materials science 9 (1998), S. 403-407 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract An experimental animal model was used to investigate the effect of bioactive glass (BG) granules and nonresorbable polytetrafluoroethylene (PTFE) membrane on the repair of cortical bone defects adjacent to titanium and BG implants. Thirty-two Astra® (diameter 3.5 mm) dental implants were inserted bicortically and 42 conical BG implants (diameter 2.5–3.0 mm) monocortically, into fitted holes of rabbit tibia. Before implantation, a standardized bone defect was created by drilling an extra hole (diameter 3.0 mm) adjacent to each implant site. Twenty-eight defects were filled with BG granules (diameter 630–800 μm) (BG group) and 28 defects were left empty but covered with PTFE membrane (PTFE group). No material was used in 18 control defects (control group). Morphometrical evaluation with a digital image analysis system was used to measure bone repair as percentages of the defect area on scanning electron microscopy (SEM) and light microscopy pictures. Bone–implant contact was measured as percentages of the thickness of the cortical bone. At 6 and 12 wk, bone repair in defects in connection with titanium implants was 23.2% and 36.6% in the BG group, 23.2% and 32.4% in the PTFE group, and 47.2% and 46.2% in control defects. Corresponding figures for BG implants were 33.2% and 40.1% in the BG group, 16.6% and 33.5% in the PTFE group, and 25.7% and 54.9% in control defects, BG granules and new bone together filled 82.7% and 68.5% of the defect area adjacent to titanium implants, and 75.9% and 74.4% of the defect adjacent to BG implants at 6 and 12 wk, respectively. Better bone–implant contact was achieved at the defect side with BG than titanium implants (77.0% versus 45.0% at 12 wk). The results indicate that BG granules are useful in treatment of bone defects adjacent to dental implants. BG coating of the implant seems to improve osseointegration in the defect area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1013235630347
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  • 4
    Electronic Resource
    Electronic Resource
    The stability of hydroxyapatite in an optimized bioactive glass matrix at sintering temperatures (1991)
    Springer
    Journal of materials science 2 (1991), S. 133-137 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The stability of sintered hydroxylapatite particles was studied in glass matrices of the system SiO2-CaO-P2O5-Na2O-Al2O3-B2O3 at sintering temperatures between 700 and 1000 °C. The results from X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDX) analysis, transmission electron microscopy (TEM) and electron diffraction showed that above 700 °C the Na+ ions diffuse into the hydroxylapatite particles which then transform into rhenanite. The glass matrix undergoes crystallization yielding wollastonite crystals and a silica rich matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692970
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  • 5
    Electronic Resource
    Electronic Resource
    Bioactive glass and glass-ceramic-coated hip endoprosthesis: experimental study in rabbit (1995)
    Springer
    Journal of materials science 6 (1995), S. 14-18 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Co−Cr−Mo endoprostheses with a dual bioactive glass (BG) coating and titanium implants coated with a bioactive glass-ceramic (BGC) were studied under lead-bearing conditions in the rabbit hip. The dual BG coating contained an inner layer of high durability and an outer bioactive layer. Each type of coating improved the stabilization of prosthesis during the experiment period of 8 weeks compared to non-coated control implants. EDXA analysis confirmed the ability of BG and BGC coatings to bond chemically to bone. The BGC coating on titanium alloy proved superior to the dual BG coating on Co−Cr−Mo prosthesis with regard to bone formation on the surface of the implant. The bioactive top layer of the dual BG coating showed resorption, especially in the areas without direct bone contact. This is explained by partial crystallization of the glass during firing. Thermal discrepancy between BGC coating and titanium core caused cracking of the coating, which remains a major obstacle to its use as a bioactive coating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121240
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  • 6
    Electronic Resource
    Electronic Resource
    In vivo reactions of Ca,P particle containing surface reactive glasses (1994)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 993-1002 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Four Ca,P particle containing surface reactive glass composites and two glasses(in the SiO2-aO-P2O5-Na2O-Al2O3 system) were implanted in the diaphyseal area of goat femora up to 24 weeks. Scanning electron microscopic, energy dispersive x-ray, and histological analysis were performed to evaluate the material-tissue interactions. A new type of integration mechanism was observed. Instead of the bone growing to the material surface, a gel-like silica formation appeared between the cortex bone and the material surface. In time the gel-like formation was replaced by a Ca,P layer. The results provided indirect evidence that pure silica gel formed in the tissues could also achieve an apatite layer formation and bone bonding on its surface. © 1994 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820280904
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  • 7
    Electronic Resource
    Electronic Resource
    Protein adsorption to a bioactive glass with special reference to precorrosion (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 31 (1996), S. 525-531 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The protein adsorption properties of the bioactive glass S53P4 were studied using albumin, IgG, and fibrinogen solutions (1 mg/mL) as well as diluted plasma, serum, and 1:1:1 mixtures of albumin, IgG, and fibrinogen. The bioactive glass granules (315-500 μm) were used in the experiments without pretreatments or as precorroded with an Si-rich or a Ca,P-rich layer. The protein adsorption properties of S53P4 were compared to a commercial bioactive glass (Bioglass®), an inert glass, an experimental glass ceramic, titanium (Ti), and hydroxyapatite (HA). The untreated S53P4 bound in Tris-buffered saline mainly albumin from diluted plasma and serum and the 1:1:1 (1 mg of each) mixture of albumin, IgG, and fibrinogen. No binding of fibrinogen was observed. The omission of NaCl from the buffer used in the experiments increased the number of proteins bound by the S53P4. Most of the albumin bound by the glass could be detached with 0.5-1M NaCl speaking for electrostatic protein bonding. The protein adsorption properties of Bioglass® resembled those of S53P4. The Ca,P-rich layer glass, the inert glass, the glass ceramic, HA, and Ti all bound several plasma and serum proteins, including fibrinogen. The Si-rich layer glass showed protein binding properties resembling the untreated glass more than the Ca,P-rich layer glass. The protein adsorption test used in the present study revealed differences in the protein adsorption properties of the studied materials, which may reflect differences in their surface potentials. It also functioned in registration of corrosion-induced changes in the surface properties of the S53P4. As judged by the protein adsorption properties, the untreated S53P4 could have a higher biocompatibility than the two precorroded glasses. Precorrosion, especially the formation of the Ca,P-rich layer, increased the number of proteins bound by the S53P4. Thus, a precorroded glass as compared to the untreated glass could be a better carrier of specific proteins that may be used to improve the biocompatibility of the bioactive glass. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation of dense hydroxylapatite or rhenanite containing bioactive glass composites (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 663-674 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of time at 600°C and of small additions of Al2O3 and B2O3 on the sintering of two composite materials of (1) hydroxylapatite (C ∼I O (P O ∼)∼(O H )∼) and bioactive glass (SiO2-CaO-P2O5-Na2O) or (2) rhenanite (CaNaPO,) and bioactive glass were studied. Scanning microscopy, quantitative EDX, x-ray diffraction, helium gas density measurements, and diametral measurements were performed on the resulting composites. No reactions were observed with the SEM or XRD between the hydroxylapatite particles and the glass matrix within sufficient sintering times to achieve maximum density. (∼) The rhenanitecontaining composites were observed to form Na2O2CaO3SiO2 crystals by x-ray diffraction, probably as a result of dissolution of the rhenanite particle surfaces into the glass phase, the crystals formed in the glass or at the interface of the glass, and the ceramic particles. However, within the short sintering times needed to achieve maximum density the rhenanite particles remained mostly intact. The rhenanitecontaining materials gave better results than the hydroxylapatite-containing materials. The glass composition had a great effect on the densification process.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260508
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  • 9
    Electronic Resource
    Electronic Resource
    Dissolution and scanning electron microscopic studies of Ca,P particle-containing bioactive glasses (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 1225-1233 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Calcium phosphate (Ca, P) precipitation behavior on the surface of two bioactive glasses and four bioactive glass composites - two with hydroxylapatite (Ca10(PO4)6(OH)2) and two with rhenanite (CaNaPO4) - were studied in simulated body fluid (SBF) and in Tris-Buffer at 5, 8, 16, 24, 48, 72, and 144 h. The Weight loss of the materials was measured and the amount of precipitation was estimated using scanning electron microscopy with electrochemical detection (SEM-EDX) analysis. The test was repeated for one glass and its respective rhenanite composite every 3 h until 60 h and thereafter every 10 h until 150 h in SBF. Atomic absorption spectroscopy, spectrophotometry, SEM-EDX analysis, and pH measurements were performed on these samples. It is shown that in vitro the composite materials have a higher capacity for Ca, P precipitation than the glasses. Weight losses of the materials correlate well with their composition. Both the glass and Ca, P phases influence the precipitation mechanism and rate. Precipitation begins preferably from the glass phase. Ca, P particles clearly influence the time of onset and rate of precipitation. Cross-sectional EDX analysis of the samples revealed an absence of a clear Sirich layer in glass AOBO (SiO2 53.9 mol %, Na2O 27.5, CaO 12.4, P2O5 6.2, Al2O3 0.0 and B2O3 0.0) composites. This was attributed to the presence of extra calcium and phosphate ions on the surface of the material. The ion-concentration and pH change curves offered insight into the mechanism of precipitation. A connection was established between SEM-EDX results and the release curves. Formation of an Si, Ca, Na film was observed that seemed to initiate the Ca, P precipitation. It is speculated that it is a characteristic of this particular glass composition. Two possible models for the mechanism of Ca, P precipitation are discussed. Phosphate polycondensation with silicate network or Ca binding to silicate network can both explain the results and it is assumed that in general both mechanisms play a role in the precipitation process. © 1993 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820271003
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  • 10
    Electronic Resource
    Electronic Resource
    Histomorphometric and molecular biologic comparison of bioactive glass granules and autogenous bone grafts in augmentation of bone defect healing (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 35 (1997), S. 9-17 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The applicability of bioactive glass (BG) granules as a substitute for bone grafts was tested by comparing the histologic, histomorphometric, and molecular biologic healing patterns to those of bone autografts and ungrafted bone defects in a rat model. The cellular response in defects filled with BG granules was characterized by continuous overexpression of type III collagen. Osteogenic mesenchymal cells, prior to their differentiation to osteoblasts, organized as a dense periosteumlike layer on the surface of the BG granules. By day 14 new bone formation was more extensive in autografted defects than in BG filled defects (p = 0.039). No cartilage-specific type II collagen mRNA was detectable, confirming the uniformity of intramembranous bone formation. The difference in the initiation of new bone formation was further confirmed by the mRNA analyses of the de novo production of TGF-β1 and type I collagen. Autografted defects demonstrated the highest levels of TGF-β1 and type I collagen mRNAs during the first 2 weeks of healing, whereas BG-filled defects showed biphasic expression patterns of the same genes. Spontaneous new bone formation in ungrafted bone defects was also characterized by biphasic expression of type I collagen gene. Osteonectin mRNA declined gradually over time in autografted and BG filled defects, whereas unfilled defects showed a gradual increase of osteonectin mRNA during healing. By 8 weeks, about 70% of the BG surface showed evidence of direct new bone contact. Energy-dispersing X-ray analyses confirmed the presence of silica-rich and CaP-rich zones at the bonding interface. In conclusion, the osteoconductive surface of bioactive glass granules efficiently bonds to ongrowing new bone but the material does not reach the capacity of autogenous bone graft in promotion of osteogenesis. © 1997 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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