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Träfflista för sökning "WFRF:(Wennerberg Ann 1955 ) ;lar1:(cth);pers:(Andersson Martin 1974)"

Sökning: WFRF:(Wennerberg Ann 1955 ) > Chalmers tekniska högskola > Andersson Martin 1974

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1.
  • Arvidsson, Anna, 1973-, et al. (författare)
  • Formation of calcium phosphates on titanium implants with four different bioactive surface preparations. An in vitro study
  • 2007
  • Ingår i: Journal of Materials Science-Materials in Medicine. - 0957-4530. ; 18:10, s. 1945-1954
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of the present study was to compare the nucleating and growing behaviour on four types of bioactive surfaces by using the simulated body fluid (SBF) model. Titanium discs were blasted and then prepared by alkali and heat treatment, anodic oxidation, fluoridation, or hydroxyapatite coating. The discs were immersed in SBF for 1, 2, 4 and 6 weeks. Calcium phosphates were found on all specimens, as analysed with scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). After 1 and 2 weeks of SBF immersion more titanium was accessible with SEM/EDX on the blasted surfaces than the four bioactive surface types, indicating a difference in coverage by calcium phosphates. The Ca/P mean ratio of the surfaces was approximately 1.5 after 1 week, in contrast to the fluoridated specimens which displayed a Ca/P mean ratio of approximately 2. Powder X-ray diffraction (P-XRD) analyses showed the presence of hydroxyapatite on all types of surfaces after 4 and 6 weeks of immersion. The samples immersed for 6 weeks showed a higher degree of crystallinity than the samples immersed for 4 weeks. In conclusion, differences appeared at the early SBF immersion times of 1 and 2 weeks between controls and bioactive surface types, as well as between different bioactive surface types.
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2.
  • Hayashi, Mariko, et al. (författare)
  • In vitro characterization and osteoblast responses to nanostructured photocatalytic TiO2 coated surfaces.
  • 2012
  • Ingår i: Acta biomaterialia. - 1878-7568. ; 8:6, s. 2411-6
  • Tidskriftsartikel (refereegranskat)abstract
    • The aims of the study were to characterize a nanostructured photoactive titanium dioxide (TiO(2)) coating and to compare the cellular response of human osteoblasts before and after ultraviolet (UV) irradiation of the coating. A specific nanostructured TiO(2) powder (Degussa P-25), which consists of approximately 80% anatase and 20% rutile, was spin-coated onto commercially pure titanium discs, and was heat-treated thereafter. After topographical, chemical and photocatalytic property characterizations, human osteoblasts were cultured on the coated discs before and after UV irradiation. Cell morphology was evaluated by scanning electron microscopy (SEM), and cell viability was analysed by 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay. From the contact angle analysis, the wettability significantly improved after UV irradiation. The cultured cells were flattened with numerous elongated lammellipodia; however, no morphological differences were indicated between -UV and +UV surfaces. The MTT assay analysis showed that -UV surface presented significantly higher viability compared to the +UV surface except for one cell population group at 3h where there were no differences. The nanostructured photoactive TiO(2) surface improved its hydrophilicity by UV irradiation, however no enhancing effect in cell response was confirmed at the time tested compared to the non-irradiated surface.
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3.
  • Jimbo, Ryo, 1979-, et al. (författare)
  • Genetic Responses to Nanostructured Calcium-phosphate-coated Implants.
  • 2011
  • Ingår i: Journal of dental research. - 1544-0591. ; 90:12, s. 1422-7
  • Tidskriftsartikel (refereegranskat)abstract
    • Nanostructured calcium phosphate (CaP) has been histologically and biomechanically proven to enhance osseointegration of implants; however, conventional techniques were not sufficiently sensitive to capture its biological effects fully. Here, we compared the conventional removal torque (RTQ) evaluation and gene expression in tissues around nanostructured CaP-coated implants, using real-time RT-PCR, with those of uncoated implants, in a rabbit model. At 2 wks, RTQ values were significantly higher, alkaline phosphatase (ALP) expression was significantly higher, and runt-related transcription factor 2 and tumor necrosis factor-α expressions were significantly lower in the coated than in the uncoated implants. This indicates that inflammatory responses were suppressed and osteoprogenitor activity increased around the CaP-coated surface. At 4 wks, although RTQ values did not significantly differ between the 2 groups, ALP and osteocalcin (OCN) were significantly up-regulated in the coated group, indicating progressive mineralization of the bone around the implant. Moreover, an osteoclast marker, adenosine triphosphatase, which indicates acidification of the resorption lacunae, was significantly higher for the coated implants, suggesting gradual resorption of the CaP coating. This study reveals detailed genetic responses to nanostructured CaP-coated implants and provides evidence that the effect of nanotopography is significant during the osseointegration cascade.
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4.
  • Karlsson, Johan, 1984-, et al. (författare)
  • In vivo biomechanical stability of osseointegrating mesoporous TiO2 implants
  • 2012
  • Ingår i: Acta Biomaterialia. - 1742-7061. ; 8:12, s. 4438-4446
  • Tidskriftsartikel (refereegranskat)abstract
    • Mesoporous materials are of high interest as implant coatings to receive an enhanced osseointegration. In this study, titanium implants coated with mesoporous TiO(2) thin films have been evaluated both in vitro and in vivo. Material characterization showed that, with partly crystalline TiO(2) (anatase), long-range-ordered hydrophilic mesoporous thin films with a pore size of 6nm were obtained. Evaluation of the mechanical resistance showed that the films were robust enough to withstand the standard implantation procedure. In vitro apatite formation was studied using simulated body fluids, showing that the pores are accessible for ions and that formation of apatite was increased due to the presence of the mesopores. An in vivo study using a rabbit model was executed in which the removal torque and histomorphometry were evaluated. The results show that the biomechanical stability of the TiO(2) coating was unaffected by the presence of mesopores and that osseointegration was achieved without any signs of inflammation.
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5.
  • 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. - 1708-8208. ; 10:4, s. 245-254
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE: Hydroxyapatite (HA) or titania nanostructures 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. MATERIALS 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 nanometer 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 histological analyses of the bone response (4 weeks) were 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 contact values of the nano-titania implants showed a tendency to have a higher percentage as compared to the nano-HA implants (p = .1). CONCLUSION: Thus, no evidence of enhanced bone formation to nano-HA-modified implants was observed compared to nano-titania-modified implants. The presence of specific nanostructures dependent on the surface modification exhibiting different size and distribution did modulate in vivo bone response.
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6.
  • Meirelles, Luiz, 1974-, et al. (författare)
  • Nano hydroxyapatite structures influence early bone formation
  • 2008
  • Ingår i: Journal Biomedical Materials Research - A. - 1549-3296. ; 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 microm(2) 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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7.
  • Svanborg, Lory Melin, et al. (författare)
  • Surface characterization of commercial oral implants on the nanometer level.
  • 2010
  • Ingår i: Journal of biomedical materials research. Part B, Applied biomaterials. - 1552-4981. ; 92B:2, s. 462-469
  • Tidskriftsartikel (refereegranskat)abstract
    • Lately, there has been a growing interest in how the presence of nanometer structures on a bone integrated implant surface influences the healing process. Recent in vitro studies have revealed an increased osteoblast response to different nanophase surfaces. Some commercial implant brands claim their implants have nanometer structures. However, at present, there are no studies where the nano topography of today's commercially available oral implants has been investigated. The aim of this study was to characterize commercial oral implants on the nanometer level and to investigate whether or not the nanometer surface roughness was correlated to the more well-known micrometer roughness on the implants. Twelve different commercial screw-shaped oral implants with various surface modifications were examined using scanning electron microscopy and a white light interferometer. The interferometer is suitable for detection of nanoscale roughness in the vertical dimension; however, limitation exists on the horizontal due to the wavelength of the light. A 1 x 1 microm Gaussian filter was found to be useful for identifying nm roughness with respect to height deviation. The results demonstrated that an implant that was smooth on the micrometer level was not necessarily smooth on the nanometer level. Different structures in the nanometer scale was found on some of the implants, indicating that to fully understand the relationship between the properties of an implant surface and its osseointegration behavior, a characterization at the nanometer scale might be relevant.
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8.
  • 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. - 1399-0020. ; 40:3, s. 308
  • 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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9.
  • 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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10.
  • Wennerberg, Ann, 1955-, et al. (författare)
  • Spontaneously formed nanostructures on titanium surfaces.
  • 2013
  • Ingår i: Clinical Oral Implants Research. - 0905-7161. ; 24:2, s. 203-209
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: The aim was to investigate the evolution of nanostructures on the SLActive surface, as a function of time, storage conditions, material dependence and to identify the step in which the reorganization of the outermost titanium oxide layer into well defined nanostructures takes place. MATERIAL AND METHODS: Titanium grade 2 discs were surface modified in seven different modes; (1) SLA (sand blasted, large grit, acid etched) protocol. (2) SLActive protocol (SLA stored in 0.9% NaCl solution), (3) SLActive, but stored in water instead of 0.9% NaCl solution, (4) pmod SLA: SLA discs subjected to oxygen plasma cleaning and stored in 0.9% NaCl solution, (5) SLAnano: SLActive discs aged for several months and then dried, (6) Mod A: same etching procedure and storage as for SLActive, but no sand blasting prior to etching, (7) pmod P: the discs were polished, oxygen plasma cleaned and stored in 0.9% NaCl solution. In addition TiZr alloy discs were prepared like the Ti SLActive samples. The surfaces were evaluated with SEM, interferometry, contact angle measurements and XPS. RESULTS: The samples stored dry were hydrophobic whereas the discs stored in liquid were hydrophilic. The evolution of nanostructures took 2 weeks, thereafter they were stable over time. The nanostructures occured after storage both in water and NaCl solution. Nanostructures were formed on Ti and TiZr although the morphology and distribution was quite different between the two materials. CONCLUSIONS: Acid etching in conjunction with storage in aqueous solution is responsible for the reorganization of the outermost titanium oxide layer into well defined nanostructures.
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