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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 523 (1988), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 523 (1988), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 18 (1991), S. 0 
    ISSN: 1365-2842
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Calcium-phosphate ceramic particulates are often used as filler material for enhanced repair of dental bone defects. Although evidence of bone ingrowth in the scaffold of these particles has been described, it is not observed consistently. Fibrous tissue often encapsulates these particles, which can subsequently become dispersed into the surrounding tissues or even exfoliated. The aim of the present study was to evaluate bioactive glass granules (Biogran ™)* as a filler for osseous lesions, and to compare them with two commercially available Hydroxylapatite (HA) granules. The particulates were implanted in the jaws of five beagle dogs, resected and evaluated after 1, 2, 3, 6 and 12 months of implantation. Histological analysis revealed an improvement in repair of all the lesions. A massive osteoconductive bone growth was seen near the walls of the bony cavities, but in greater amounts around the bioactive glass granules than around the HA materials. On top of this massive growth a trabecular bone growth was observed in the centre of the bony cavities. These trabeculae were associated with the glass particles, which exhibited osteophilic properties, while fibrous tissue separated the bone tissue from the HA particles. The centres of many of the particles are excavated, and are subsequently filled by newly formed bone tissue. This internally formed bone tissue is not necessarily connected to the surrounding bone tissue, and functions as a nucleation site for further bone repair. For the mesenchymal cells within the eroded glass particles this inner environment acts as a stimulus to differentiate into osteoblasts and to start their osteogenetic potential. This phenomenon was not observed around the HA materials. If the latter were surrounded by fibrous tissue, disintegration of the surface by giant cells was observed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 15 (1988), S. 0 
    ISSN: 1365-2842
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Bioactive glass has the ability to bond with bone, but it cannot be used as a load bearing device due to its limited mechanical properties. By reinforcing bioactive glass with a ductile second phase, a structurally reliable material is obtained.The aim of the present study was to evaluate histologically and morphometrically the interfacial behaviour of submerged composite dental root implants. Therefore, bulk and composite implants were subgingivally installed in the partially edentulous jaws of Beagle dogs and harvested after 4 and 16 months.Histologically, the connection between the implants and bone tissue could be clearly demonstrated. This bone connection is mainly located at the cortical bone level. In the vicinity of the infraalveolar nerve a fibrous tissue contact was found.It is shown that surgical trauma, motion at the glass to tissue interface, and gross ion dissolution from the material adversely affect the interfacial osteogenesis. If these factors are controlled, bone bonding is found over a larger area than the initial area of contact between the implant and bone tissue. This means that bone grows out along the implant surface, starting from the initial contact area.No difference was observed between the interfacial behaviour of bulk bioactive glass and intact fibre reinforced bioactive glass implants.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 24 (1997), S. 0 
    ISSN: 1365-2842
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: summary The aim of this study was to evaluate bone growth around bioactive glass particles in bone defects in comparison to hydroxylapatite particles. The bioactive glass particles were implanted in the partial edentulous jaws of Beagle dogs in two different compositions and several sizes and size ranges. After 1, 2, 3, 6, 12 and 24 months the samples were harvested and processed for undecalcified sectioning. Histological analysis showed a superior response of the bioactive glass particles of composition A and narrow size range (300-355 μm). Besides extensive osteoconductive properties, the bone repair was also stimulated by bone growth in the internally eroded particles. The data demonstrate conclusively that the well known corrosion reactions of the bioactive glass lead to the formation of protective pouches. In these protective pouches formation of new bone is detected without this bone being connected to the bone tissue outside the particles. These islands of newly formed bone tissue function as nuclei for further bone growth and enhance the repair of the defect.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 4 (1993), S. 117-126 
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: The dissolution of titanium in simulated interstitial electrolyte (SIE), human serum in SIE (serum/SIE) and 8.0 mM ethylenediaminetetraacetic acid (EDTA) in SIE (EDTA/SIE) was measured in vitro. Titanium fibre samples were immersed in these solutions and maintained at 37°C, 10% O2, 5% CO2 and 97±3% relative humidity for 0–5000 h. The concentration of titanium released was quantified using electrothermal atomic absorption spectroscopy. Changes in oxide stoichiometry were determined by Auger electron spectroscopy after processing and immersion in the test solutions. The oxide became nearly stoichiometric TiO2 after immersion, suggesting equilibration of the surface with the solutions. Solution ligands enhanced the magnitude of dissolution, with EDTA〉serum/SIE〉SIE. The dissolution kinetics were empirically fitted by a two-phase logarithmic relationship. The first phase of dissolution (t〈300 h) was dominated by equilibration of the oxide with the solution and the second phase (t〉300 h) by mass diffusion. The dissolution kinetics were similar for the EDTA/SIE and serum/SIE solutions, indicating that the mechanisms of dissolution for each solution may be the same.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 3 (1992), S. 28-32 
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract In an effort to understand thein vivo interactions of titanium and its alloys with a biological environment, surface science methods have been used on specimens retrieved fromin vitro andin vivo experiments. A relatively new technique that has the potential to further our knowledge of the oxide-solution interface is scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (TS). This work documents the use of STM/TS in the study of titanium thin films before and after immersion in anin vitro solution. Titanium thin films were fabricated using a procedure which produced an oxide that had minimal contaminants. Half of the thin films were immersed in an electrolyte. STM/TS was performed immediately after the immersion period. Constant current images were obtained. Current-voltage characteristics were recorded at regions of interest. The topography of the nonimmersed films revealed that the surface was qualitatively the same as other sputter deposited metal films. I–V curves showed little spatial variation. The topography of the immersed film showed little change from the nonimmersed ones. However, significant spatial variation of the local electronic structure was noted. This indicates that titanium surface-fluid interactions do not occur uniformly on the film.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 8 (1997), S. 525-529 
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract All non-noble metals and alloys will release metallic species into the body. This raises the issue of amount and fate, i.e. transport and storage, of these metal dissolution products. For titanium, the nature and extent of these systemic effects remain mostly unknown. In this study we investigated titanium levels in alleged target tissues in rabbits, both with and without a titanium implant functioning in the absence of wear, and compare these results to the limited body of literature concerning systemic levels of titanium. Titanium fibre felts were implanted into the tibia of rabbits. At various time points, lung, spleen, and muscle samples were collected from these rabbits as well as two groups of control rabbits. The samples were analysed for titanium concentration using electrothermal atomic absorption spectrophotometry. The data for the implant groups show that titanium levels in these tissues do not increase in comparison with controls up to 1 y after implantation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 3 (1992), S. 33-42 
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract Plasma spraying is a commonly used technique to apply thin calcium phosphate ceramic coatings. Special consideration is given to retaining the original structure of CPC particles. However, changes are possible. Thus this study focused on plasma spraying induced changes in material characteristics of commercial coatings and their influence onin vitro dissolution. All analysed coatings were found to undergo significant plasma spraying induced changes in phase composition, crystal structure, and specific surface area. The phase transformations depended on the starting particle characteristics. Specifically, β-TCP transformed to α-TCP. HA was dehydroxylated and transformed to oxyhydroxyapatite (OHA), and partly decomposed to α-TCP and tetra calcium phosphate. These transformations lead to a considerable increase ofin vitro dissolution rates at physiological pH.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 4 (1993), S. 165-168 
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: The determination of the calcium to phosphate ratio (Ca/P) in Ca-deficient hydroxyapatite [d-HAP; Ca10−x (HPO4) x (PO4)6−x (OH)2−x ] using X-ray diffraction analysis (XRD) is reported. At temperatures above 700°C HPO4 2- groups are transformed to PO4 3- groups, thereby producing β-tricalcium phosphate [β-TCP; Ca3(PO4)2]. Thus, the deviation from stoichiometry, x, can be calculated from the mass fraction of β-TCP, which in turn can be determined from quantitative XRD analyses. In this study d-HAP powders with various Ca/P ratios were prepared following several procedures. It is shown that the Ca/P ratio determined by quantitative XRD correlates well with that measured by chemical analyses.
    Materialart: Digitale Medien
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