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Sökning: WFRF:(Wennerberg Ann 1955 ) > Chalmers tekniska högskola

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11.
  • Meirelles, Luiz, 1974, et al. (författare)
  • Effect of hydroxyapatite and titania nanostructures on early in vivo bone response
  • 2008
  • Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1708-8208 .- 1523-0899. ; 10:4, s. 245-254
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: Hydroxyapatite or titania nano structures were applied on smooth titanium implant cylinders. The aim was to investigate whether nano HA may result in enhanced osseointegration compared to nano titania structures. Material and Methods: Surface topography evaluation included detailed characterization of nano size structures present at the implant surface combined with surface roughness parameters at the micro- and nano- meter level of resolution. Microstructures were removed from the surface to ensure that bone response observed was dependent only on the nanotopography and/or chemistry of the surface. Early in vivo bone response (4 weeks) evaluation was investigated in a rabbit model. Results: In the present study, nano titania coated implants showed an increased coverage area and feature density, forming a homogenous layer compared to nano HA implants. Bone response observed at 4 weeks could not be explained by the surface chemistry. New formed bone connected to the original cortical bone demonstrated an increase of 24% for the nano titania compared to the nano HA implant, although the difference was not statistically significant. Conclusion: Thus, no evidence of enhanced bone formation to nano hydroxyapatite modified implants was observed compared to nano titania modified implants. The presence of specific nano structures; dependent on the surface modification exhibiting different size and distribution did modulate in vivo bone response.
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12.
  • Meirelles, Luiz, 1974, et al. (författare)
  • Nano hydroxyapatite structures influence early bone formation
  • 2008
  • Ingår i: Journal Biomedical Materials Research - A. - : Wiley. - 1549-3296 .- 1552-4965. ; 87:2, s. 299-307
  • Tidskriftsartikel (refereegranskat)abstract
    • In a study model that aims to evaluate the effect of nanotopography on bone formation, micrometer structures known to alter bone formation, should be removed. Electropolished titanium implants were prepared to obtain a surface topography in the absence of micro structures, thereafter the implants were divided in two groups. The test group was modified with nanosize hydroxyapatite particles; the other group was left uncoated and served as control for the experiment. Topographical evaluation demonstrated increased nanoroughness parameters for the nano-HA implant and higher surface porosity compared to the control implant. The detected features had increased size and diameter equivalent to the nano-HA crystals present in the solution and the relative frequency of the feature size and diameter was very similar. Furthermore, feature density per m2 showed a decrease of 13.5% on the nano-HA implant. Chemical characterization revealed calcium and phosphorous ions on the modified implants, whereas the control implants consisted of pure titanium oxide. Histological evaluation demonstrated significantly increased bone formation to the coated (p < 0.05) compared to uncoated implants after 4 weeks of healing. These findings indicate for the first time that early bone formation is dependent on the nanosize hydroxyapatite features, but we are unaware if we see an isolated effect of the chemistry or of the nanotopography or a combination of both.
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13.
  • Meirelles, Luiz, 1974, et al. (författare)
  • The effect of chemical and nano topographical modifications on early stage of osseointegration
  • 2008
  • Ingår i: The International Journal of Oral & Maxillofacial Implants. - 0882-2786. ; 23:4, s. 641-7
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: To investigate the effect of chemically modified implants with similar micro but different nano topography on early stage of osseointegration. Materials and Methods: Screw shaped implants were placed in the flat proximal medial tibial methaphyses of 10 New Zealand white rabbits. Blasted (control); blasted-fluoride and blasted-nano HA implants were investigated. Surface evaluation included chemical analyses with x-ray photoelectron spectroscopy, morphological analyses with scanning electron microscopy and topographical analyses with interferometry. Bone response was investigated with removal torque measurements and histological analyses after a healing period of 4 weeks. Results: Chemical analyses revealed the presence of Ti, O, C and N in all implant groups. The blasted-F group revealed F and the blasted nano HA group Ca and P with simultaneous decrease of Ti and O. Surface roughness parameters showed a slight decrease of the average height deviation for the blasted nano-HA and blasted-F compared to the blasted control implants. SEM images at high magnification indicated the presence of nano structures on the chemically modified implants. Removal torque (RTQ) mean values revealed an increase of 17% to 25% for the chemically modified implants compared to the control implants and the histological analyses demonstrated a similar enhanced bone formation to the chemically modified implants with nanostructures. Conclusion: Chemical modifications used in the present study were capable of producing a unique nano topography and together with the ions present at the implant surface may explain the increased RTQ and histomorphometric values after a healing period of 4 weeks.
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14.
  • Rosén, Bengt Göran, et al. (författare)
  • Topographical characterisation of artificial femoral heads : a Benchmarking study
  • 2004
  • Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 257:12, s. 1275-1280
  • Tidskriftsartikel (refereegranskat)abstract
    • The main functional demands on artificial joints are that they last more than 20 years. This means optimising the friction coefficient to minimise forces transmitted to the surrounding bone and the wear of the contacting surfaces. Surface roughness has an important influence on friction and wear. Traditionally, the 2D Ra-parameter has been the preferred way to characterise the joint's topography. Today ongoing development of 3D techniques are available for the research, and the aim of the present paper is to highlight the importance and possibilities using high-resolution 3D atomic force microscope ( AFM) and the optical phase-shifting interferometer for texture characterisation of eight commercially available femoral heads. The results show a significant variation of topography and surface-lay for the different femoral heads in the study. The variation and difference between heads were further underlined by the use of different characterisation techniques and measuring strategy. Results highlight the importance of the selection of measurement strategy, parameters, instrumentation, and scale of measurement in order properly to characterise the femoral heads in this study.
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15.
  • Svanborg, Lory Melin, et al. (författare)
  • Evaluation of bone healing on sandblasted and Acid etched implants coated with nanocrystalline hydroxyapatite: an in vivo study in rabbit femur
  • 2014
  • Ingår i: International Journal of Dentistry. - : Hindawi Limited. - 1687-8728 .- 1687-8736. ; 2014
  • Tidskriftsartikel (refereegranskat)abstract
    • This study aimed at investigating if a coating of hydroxyapatite nanocrystals would enhance bone healing over time in trabecular bone. Sandblasted and acid etched titanium implants with and without a submicron thick coat of hydroxyapatite nanocrystals (nano-HA) were implanted in rabbit femur with healing times of 2, 4, and 9 weeks. Removal torque analyses and histological evaluations were performed. The torque analysis did not show any significant differences between the implants at any healing time. The control implant showed a tendency of more newly formed bone after 4 weeks of healing and significantly higher bone area values after 9 weeks of healing. According to the results from this present study, both control and nano-HA surfaces were biocompatible and osteoconductive. A submicron thick coating of hydroxyapatite nanocrystals deposited onto blasted and acid etched screw shaped titanium implants did not enhance bone healing, as compared to blasted and etched control implants when placed in trabecular bone.
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16.
  • Svanborg, Lory Melin, et al. (författare)
  • The effect of hydroxyapatite nanocrystals on early bone formation surrounding dental implants.
  • 2011
  • Ingår i: International journal of oral and maxillofacial surgery. - : Elsevier BV. - 1399-0020 .- 0901-5027. ; 40:3, s. 308-15
  • Tidskriftsartikel (refereegranskat)abstract
    • The knowledge of how nanostructures might affect early bone healing and osseointegration is limited. The aim of this study was to investigate if nanometer thick coatings of hydroxyapatite nanocrystals applied on a moderately rough surface might enhance early bone healing on screw-shaped dental implants and to evaluate if the thickness of the coat influences healing. Sandblasted and acid etched titanium implants coated with two different thicknesses of hydroxyapatite (test implants) and sandblasted and acid etched titanium implants (control implants), were inserted in rabbit tibia. After a healing time of 2, 4 and 9 weeks, a removal torque analysis and a histological evaluation were performed. The results from the removal torque analysis showed a tendency for higher values for the double coated hydroxyapatite after 4 weeks and for both the coated surfaces after 9 weeks of healing. The histological evaluations indicated slightly more new bone formation with the coated implants compared with the control; the differences did not reach statistical significance. The present study could not support the importance of nanometer thick coatings of hydroxyapatite nanocrystals in early bone healing, at least not when applied on a blasted and etched surface and placed in a cortical bone.
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17.
  • Wennerberg, Ann, 1955, et al. (författare)
  • In vivo stability of hydroxyapatite nanoparticles coated on titanium implant surfaces.
  • 2011
  • Ingår i: The International journal of oral & maxillofacial implants. - 1942-4434. ; 26:6, s. 1161-6
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: Nanotechnology has been employed in attempts to enhance bone incorporation of dental implants. Often, nanoparticles are applied to the implant surface as particle coatings. However, the same properties that may increase the functionality may also lead to undiscovered negative effects, such as instability of the nanocoating. The aim of this study was to investigate the stability÷instability of the nanoparticles using a radiolabeling technique. Materials and Methods: Twenty threaded and turned titanium microimplants were inserted in 10 rats. All 20 implants were coated with nanometer-sized hydroxyapatite (HA) particles. In order to trace the HA nanoparticles, the particles for 16 implants were labeled with calcium 45 (45Ca). After 1, 2, 4, and 8 weeks, the implants and surrounding bone were retrieved and analyzed using autoradiography with respect to particle migration from the implant surface. Samples from the brain, liver, thymus, kidney, and blood, as well as wooden shavings from the rats' cages, were also retrieved and analyzed using liquid scintillation counting. Results: The radioactivity representing the localization of 45Ca decreased over time from the vicinity of the implant. The amounts of 45Ca found in the blood and in the rats' excretions decreased with time and corresponded well to each other. After 8 weeks, the only trace of 45Ca was found in the liver. Conclusion: The results indicated that released particles leave the body through the natural cleaning system, and the probability that the nanocoating will assemble in vital organs and thus become a potential biologic risk factor is unlikely. Int J Oral Maxillofac Implants 2011;26:1161-1166.
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