Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Length and shape of enamel crystals (1984)
    Springer
    Calcified tissue international 36 (1984), S. 550-555 
    Details
    ISSN: 1432-0827
    Keywords: Enamel crystals ; Length ; Shape ; Apatite ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary An original method for fractionating and preparing isolated crystals of homogeneous size was developed. It was demonstrated that enamel apatite crystals are at least 100 µm long. The flexibility of the very long crystallites was demonstrated. Crystal curvatures, accounting for the irregular course of the prisms through the enamel thickness, were visualized and measured. It was shown that in the deep forming enamel layer, lateral branches may grow out of the crystals and crystal fusing often occurs, inducing the crystallites to assume pyramidal shapes with their wide bases pointing toward the dentino-enamel junction and one or two tops toward Tomes' processes. During the maturation process, the two tops of the still immature crystals also fuse so that the mature crystals acquire a rodlike aspect, with parallel faces and steplike graduations along thec axis, allowing a close contact between the crystals. These results support the hypothesis that the crystallites would be continuous from the dentino-enamel junction to the surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405364
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Experimental data regarding macroporous biphasic calcium phosphate ceramics (1997)
    Springer
    European journal of orthopaedic surgery & traumatology 7 (1997), S. 79-84 
    Details
    ISSN: 1432-1068
    Keywords: Biomaterial ; Calciumphosphate ceramics ; Osteoconduction ; Resorption ; Mechanical strength ; Biomatériau ; Céramiques de phosphate de calcium ; Résorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les céramiques macroporeuses biphasées de phosphate de calcium sont biocompatibles. Leurs structures physico-chimiques sont proches de la phase minérale des tissus osseux et dentaires et assurent leur bioactivité. Très rapidement, aprè implantation en site osseux, une dissolution apparaît avec précipitation d'ions calcium et phosphore et formation de cristaux d'apatites biologiques. A court terme une résorption ostéoclastique débute l'ostéoconduction à l'intérieur des macropores. Les études mécaniques révèlent une amélioration significative des propriétés mécaniques du fait du développement de l'os trabéculaire. En site vertébral, les expérimentations animales ont démontré la cinétique de la réhabitation osseuse au sein du matériau, ce qui permet une arthrodèse postéro-latérale. La rigidité de la fusion intervertébrale est équivalente à celle obtenue avec de l'os autologue. Ainsi, pour des conditions précises d'utilisation, les céramiques poreuses de phosphate de calcium peuvent être utilisées pour combler le défect osseux et pour la réalisation d'arthrodéses postéro-latérales.
    Notes: Summary Macroporous biphasic calcium phosphate ceramics are biocompatible. Their physico-chemical structure is close to the mineral phase of the bone and provides bioactivity. Shortly after implantation in osseous area, dissolution appears with precipitation and formation of apatite crystals. Soon after osteoclastic resorption begins osteoconduction inside the macropores. Mechanical studies reveal a significant improvement in the mechanical properties due to the growth of the trabecular bone. Animal experiments in the spine have demonstrated bone penetration which allows a postero-lateral fusion. The rigidity of the fusion is equivalent to that obtained with bone graft. Macroporous biphasic calcium phosphate can be applied to fill bone defects and for postero-lateral spine fusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00578773
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    High-resolution electron microscope study of human enamel crystallites: Size, shape, and growth
    Amsterdam : Elsevier
    Journal of Ultrasructure Research 65 (1978), S. 163-172 
    Details
    ISSN: 0022-5320
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0022-5320(78)90053-9
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    High-resolution electron microscopy and crystallographic study of some biological apatites
    Amsterdam : Elsevier
    Journal of Ultrasructure Research 57 (1976), S. 266-275 
    Details
    ISSN: 0022-5320
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0022-5320(76)80116-5
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Etude Morphométrique de la Paroi de la Veine Cave Caudale après Implantation d'un Filtre chez le Mouton (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Anatomia, histologia, embryologia 27 (1998), S. 0 
    Details
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The long stabilizers of the VT-LGM filter rest on large areas of the vascular wall. The morphometric study of the layers of the vascular wall, after implantation of filter in 15 ewes, divided into 3 groups of follow-up (2, 4 or 8 weeks) of 5 animals, was made at 3 levels opposite the filter and 1 level outside of it. Changes are seen for all the layers. Filter produces intimal hyperplasia. Stabilizers are quickly isolated from the blood flow. The thickness of the intimal hyperplasia grows for 4 weeks. It is more important at the base of the filter than at its head. There is also hyperplasia of the media with no change according to the follow-up or the level opposite the filter. The adventitia becomes thinner without variation of time or level of the filter. Smooth muscle cells of the adventitia become less frequent and smaller. Their density, in front of the stabilizers, is the smallest by 4 week follow-up and remains the same along the stabilizer. The full thickness of the wall is bigger opposite the stabilizers than between them. The filter produces changes that are limited in time and in space. The most important changes are seen at 4 weeks after insertion and opposite the stabilizers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0264.1998.tb00186.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Significance of the Porosity and Physical Chemistry of Calcium Phosphate Ceramics Biodegradation-Bioresorption (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 523 (1988), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1988.tb38519.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Elaboration conditions influence physicochemical properties and in vivo bioactivity of macroporous biphasic calcium phosphate ceramics (1999)
    Springer
    Journal of materials science 10 (1999), S. 199-204 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Two different preparations of biphasic calcium phosphate (BCP) were characterized in vitro: BCP1 from a mechanical mixture of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) powders, and BCP2 from calcination of a calcium-deficient apatite (CDA). The structural, physicochemical and mechanical parameters of these two preparations were investigated, and two different macroporous BCP1 (MBCP1) and BCP2 MBCP2) implants were manufactured and implanted in rabbit bone for in vivo bioactivity studies. Scanning electron microscopy observations showed that MBCP1 implants had a significantly higher degradation rate (P〈0.0001) than MBCP2 implants. This was probably caused by the presence of calcium oxide impurities in BCP1 and the more intimate mixture and stable ultrastructure of BCP2. No significant difference about the newly formed bone rate in these two BCP preparations was observed. Very slight variations in sintering conditions appeared to influence the biodegradation behavior of the two MBCP implants despite their identical HA/β-TCP ratios and similar porosity. Precise and complete in vitro characterization enabled us to understand and predict in vivo degradation behavior. © 1999 Kluwer Academic Publishers
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008949910440
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Cellular response to calcium phosphate ceramics implanted in rabbit bone (1993)
    Springer
    Journal of materials science 4 (1993), S. 273-280 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Two hydroxyapatite ceramics, synthesized by sintering from bovine bone and from a mixture of phosphate tricalcium and natural hydroxyapatite, were implanted in bone sites in rabbits. From day 7 after implantation, osteoblast-like cells were visible with thin layers of new bone on both biomaterials. Histomorphometry showed progressive increase in volume and surface of newly formed bone. Signs of cell-dependent resorption were visible at the surface of biomaterials and newly formed bone. There was a progressive decrease in relative volume and trabecular thickness of the biomaterials. Resorption of biomaterials appears to involve two cell types: multinucleated giant cells and osteoclast-like cells. The multinucleated giant cells observed had neither tartrate resistant acid phosphatase activity (TRAP) nor a ruffled border. Vesicles and vacuoles containing crystals observed in these cells suggest phagocytosis of biomaterials. The number of these cells decreased after day 14 following implantation. The osteoclast-like cells were TRAP positive. The structured modification and the TRAP activity demonstrated in the subjacent biomaterial suggest that the dissolution of the implant may be associated to an extracellular enzymatic activity of these cells. Electron microscopy revealed a clear zone and cytoplasmic membrane infolding in these cells, suggesting a ruffled border differentiation. The number of these cells increased with delay after implantation. It was concluded that the implantation of calcium phosphate ceramics in bone leads to new bone formation as well as to resorption of the biomaterials. The mechanism of resorption appears to associate crystal endocytosis by multinucleated giant cells and more classical resorption by osteoclast-like cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122280
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Dynamic compaction of calcium phosphate biomaterials (1995)
    Springer
    Journal of materials science 6 (1995), S. 545-551 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The purpose of this study was to apply the dynamic compaction process to calcium phosphate biomaterials. this new technique is currently used to compact metallic powders at room temperature but has not been previously applied to biomaterials. A detailed study of hydroxyapatite compacts was carried out to determine shock compaction parameters. Low static precompaction (3.1 MPa) resulted in slight peripheral cracks. A compaction degree of about 70% and macrohardness of 51 Hv were achieved for a striker velocity of about 50 m/s. FTIR spectroscopy and X-ray diffraction showed no differences in structure and composition after dynamic compaction. Two other infrequently used biomaterials were also tested: an unstable octacalcium phosphate and β-calcium metaphosphate fibres. Scanning electron microscopy showed that dynamic compaction preserved the initial fibre structure of the material. No major structural or chemical changes were noted after shock consolidation. Our results show that dynamic compaction could extend the range of bioceramics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00151037
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Fourier-transform infrared spectroscopy study of an organic–mineral composite for bone and dental substitute materials (1997)
    Springer
    Journal of materials science 8 (1997), S. 621-629 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A new injectable biomaterial for bone and dental surgery is a composite consisting of a polymer as a matrix and bioactive calcium phosphate (CaP) ceramics as fillers. The stability of the polymer is essential in the production of a ready-to-use injectable sterilized biomaterial. The purpose of this study was to detect possible polymer degradation which may have been caused by the interaction with the fillers using Fourier transform infrared spectroscopy. Composites containing CaP fillers (biphasic calcium phosphate, hydroxyapatite and peroxidized hydroxyapatite) and polymer (hydroxypropyl methyl cellulose) were prepared. To investigate the properties of the polymer, the inorganic and organic phases of the composite were separated using several extraction methods. The difficulty in separating the organic (polymer) from the mineral (CaP fillers) phases in the composite investigated in this study suggested the presence of strong interactions between the two phases. Spectra of extracted polymers showed new absorption bands of low intensities and indications that some chemical modifications of the original polymers have occurred. Results also indicated that the filler composition has an effect on the integrity of the polymer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018519419539
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...