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

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  • Wennerberg, Ann, 1955-, et al. (författare)
  • Titanium release from implants prepared with different surface roughness
  • 2004
  • Ingår i: Clin Oral Implants Res. ; 15:5, s. 505-12
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: There may be a risk of greater ion release for surface-enlarged implants than conventionally turned components. The major aim of the present paper was to investigate whether a correlation exists between ion release and a surface roughness relevant for today's commercial implants. Other aims were to compare ion release after two insertion times and concentration in bone tissue as a function of distance from the implant surface. MATERIAL AND METHODS: Lactic acid aqueous solution (pH=2.3) and phosphate-buffered saline were used for the in vitro investigation. For the in vivo investigation, synchrotron radiation X-ray fluorescence (SRXRF) spectroscopy and secondary ion mass spectroscopy (SIMS) were performed 12 weeks and 1 year after implantation in rabbit tibiae. RESULTS: The average height deviation (S(a)) was 0.7, 1.27, 1.43 and 2.21 microm, respectively, for the four surfaces investigated. No difference in ion release was found in vitro. In vivo, SRXRF demonstrated slightly higher values for the roughest surface up to a distance of 400 microm from the implant surface; thereafter no difference was found. SIMS demonstrated no difference in ion release for the roughest and smoothest surfaces, but slightly more titanium in bone tissue after 1 year than after 12 weeks. Titanium rapidly decreased with distance from the implant surface. CONCLUSION: At a level relevant for commercial oral implants, no correlation was found between increasing roughness and ion release, neither in vitro nor in vivo.
  • 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.
  • Bougas, Kostas, et al. (författare)
  • In vitro Evaluation of Calcium Phosphate Precipitation on Possibly Bioactive Titanium Surfaces in the Presence of Laminin.
  • 2011
  • Ingår i: Journal of Oral & Maxillofacial Research. - 2029-283X. ; 2:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: The aim of the present study was to evaluate calcium phosphate precipitation and the amount of precipitated protein on three potentially bioactive surfaces when adding laminin in simulated body fluid. Material and Methods: Blasted titanium discs were prepared by three different techniques claimed to provide bioactivity: alkali and heat treatment (AH), anodic oxidation (AO) or hydroxyapatite coating (HA). A blasted surface incubated in laminin-containing simulated body fuid served as a positive control (B) while a blasted surface incubated in non laminin-containing simulated body fuid served as a negative control (B-). The immersion time was 1 hour, 24 hours, 72 hours and 1 week. Surface topography was investigated by interferometry and morphology by Scanning Electron Microscopy (SEM). Analysis of the precipitated calcium and phosphorous was performed by Energy Dispersive X-ray Spectroscopy (EDX) and the adsorbed laminin was quantified by iodine (125I) labeling. Results: SEM demonstrated that all specimens except for the negative control were totally covered with calcium phosphate (CaP) after 1 week. EDX revealed that B- demonstrated lower sum of Ca and P levels compared to the other groups after 1 week. Iodine labeling demonstrated that laminin precipitated in a similar manner on the possibly bioactive surfaces as on the positive control surface. Conclusions: Our results indicate that laminin precipitates equally on all tested titanium surfaces and may function as a nucleation center thus locally elevating the calcium concentration. Nevertheless further studies are required to clarify the role of laminin in the interaction of biomaterials with the host bone tissue.
  • Bougas, Kostas, et al. (författare)
  • Laminin Coating Promotes Calcium Phosphate Precipitation on Titanium Discs in vitro.
  • 2011
  • Ingår i: Journal of Oral & Maxillofacial Research. - 2029-283X. ; 2:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: The objective of this study was to investigate the effect of a laminin coating on calcium phosphate precipitation on three potentially bioactive titanium surfaces in simulated body fluid.Material and Methods: Blasted titanium discs were prepared by alkali and heat treatment (AH), anodic oxidation (AO) or hydroxyapatite coating (HA) and subsequently coated with laminin. A laminin coated blasted surface (B) served as a positive control while a blasted non coated (B-) served as a negative control. Surface morphology was examined by Scanning Electron Microscopy (SEM). The analysis of the precipitated calcium and phosphorous was performed by Energy Dispersive X-ray Spectroscopy (EDX).Results: The thickness of the laminin coating was estimated at 26 Å by ellipsometry. Interferometry revealed that the coating process did not affect any of the tested topographical parameters on µm level when comparing B to B-. After 2 weeks of incubation in SBF, the alkali-heat treated discs displayed the highest calcium phosphate deposition and the B group showed higher levels of calcium phosphate than the B- group.Conclusions: Our results suggest that laminin may have the potential to be used as a coating agent in order to enhance the osseoinductive performance of biomaterial surfaces, with the protein molecules possibly functioning as nucleation centres for apatite formation. Nevertheless, in vivo studies are required in order to clarify the longevity of the coating and its performance in the complex biological environment.
  • Franke Stenport, Victoria, 1970-, et al. (författare)
  • Precipitation of calcium phosphate in the presence of albumin on titanium implants with four different possibly bioactive surface preparations. An in vitro study
  • 2008
  • Ingår i: Journal of Materials Science: Materials in Medicine. - 0957-4530. ; 19:12, s. 3497-3505
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of the present study was to compare the nucleating behaviour on four types of bioactive surfaces by using the simulated body fluid (SBF) model with the presence albumin. Titanium discs were blasted (B) and then prepared by alkali and heat treatment (AH), anodic oxidation (AO), fluoridation (F), or hydroxyapatite coating (HA). The discs were immersed in SBF with 4.5 mg/ml albumin for 3 days, 1, 2, 3 and 4 weeks and analysed with scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX) and X-ray photoelectron spectroscopy (XPS). Topographic surface characterisation was performed with a contact stylus profilometer. The results demonstrated that the bioactive surfaces initiated an enhanced calcium phosphate (CaP) formation and a more rapid increase of protein content was present on the bioactive surfaces compared to the blasted control surface. The observation was present on all bioactive surfaces. The fact that there was a difference between the bioactive surfaces and the blasted control surface with respect to precipitation of CaP and protein content on the surfaces support the fact that there may be biochemical advantages in vivo by using a bioactive surface.
  • Galli, S., et al. (författare)
  • Local release of magnesium from mesoporous TiO2 coatings stimulates the pen-implant expression of osteogenic markers and improves osteoconductivity in vivo
  • 2014
  • Ingår i: Acta Biomaterialia. - 1742-7061. ; 10:12, s. 5193-5201
  • Tidskriftsartikel (refereegranskat)abstract
    • Local release of Mg ions from titanium implant surfaces has been shown to enhance implant retention and integration. To clarify the biological events that lead to this positive outcome, threaded implants coated with mesoporous TiO2 thin films were loaded with Mg-ions and placed in the tibia of rabbits for 3 weeks, after surface characterization. Non-loaded mesoporous coated implants were used as controls. Pen-implant gene expression of a set of osteogenic and inflammatory assays was quantified by means of real-time quantitative polymerase chain reaction. The expression of three osteogenic markers (OC, RUNX-2 and IGF-1) was significantly more pronounced in the test specimens, suggesting that the release of Mg ions directly at the implant sites may stimulate an osteogenic environment. Furthermore, bone healing around implants was evaluated on histological slides and by diffraction enhanced imaging (DEI), using synchrotron radiation. The histological analysis demonstrated new bone formation around all implants, without negative responses, with a significant increase in the number of threads filled with new bone for test surfaces. DEI analysis attested the high mineral content of the newly formed bone. Improved surface osteoconductivity and increased expression of genes involved in the bone regeneration were found for magnesium-incorporation of mesoporous TiO2 coatings.
  • Gotfredsen, Klaus, et al. (författare)
  • Implants and/or teeth: consensus statements and recommendations.
  • 2008
  • Ingår i: Journal of oral rehabilitation. - 1365-2842. ; 35:Suppl 1, s. 2-8
  • Forskningsöversikt (refereegranskat)abstract
    • In August 23-25, 2007, the Scandinavian Society for Prosthetic Dentistry in collaboration with the Danish Society of Oral Implantology arranged a consensus conference on the topic 'Implants and/or teeth'. It was preceded by a workshop in which eight focused questions were raised and answered in eight review articles using a systematic approach. Twenty-eight academicians and clinicians discussed the eight review papers with the purpose to reach consensus on questions relevant for the topic. At the conference the consensus statements were presented as well as lectures based on the review articles. In this article the methods used at the consensus workshop are briefly described followed by the statements with comments.
  • Göransson, Anna, 1970-, et al. (författare)
  • An in vitro comparison of possibly bioactive titanium implant surfaces.
  • 2009
  • Ingår i: Journal of Biomedical Materials Research Part A. - 1552-4965. ; 88:4, s. 1037-1047
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of the study was to compare Ca and P formation (CaP) and subsequent bone cell response of a blasted and four different possibly bioactive commercially pure (cp) titanium surfaces; 1. Fluoride etched (Fluoride), 2. Alkali-heat treated (AH), 3. Magnesium ion incorporated anodized (TiMgO), and 4. Nano HA coated and heat treated (nano HA) in vitro. Furthermore, to evaluate the significance of the SBF formed CaP coat on bone cell response. The surfaces were characterized by Optical Interferometry, Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). CaP formation was evaluated after 12, 24 and 72 h in simulated body fluid (SBF). Primary human mandibular osteoblast-like cells were cultured on the various surfaces subjected to SBF for 72 h. Cellular attachment, differentiation (osteocalcin) and protein production (TGF-beta(1)) was evaluated after 3 h and 10 days respectively. Despite different morphological appearances, the roughness of the differently modified surfaces was similar. The possibly bioactive surfaces gave rise to an earlier CaP formation than the blasted surface, however, after 72 h the blasted surface demonstrated increased CaP formation compared to the possibly bioactive surfaces. Subsequent bone cell attachment was correlated to neither surface roughness nor the amount of formed CaP after SBF treatment. In contrast, osteocalcin and TGF-beta(1) production were largely correlated to the amount of CaP formed on the surfaces. However, bone response (cell attachment, osteocalcin and TGF-F production) on the blasted controls were similar or increased compared to the SBF treated fluoridated, AH and TiMgO surface.
  • Hayashi, Mariko, et al. (författare)
  • Photocatalytically induced hydrophilicity influences bone remodelling at longer healing periods: a rabbit study
  • 2014
  • Ingår i: Clinical Oral Implants Research. - 0905-7161. ; 25:6, s. 749-754
  • Tidskriftsartikel (refereegranskat)abstract
    • ObjectivesPreviously, we have reported that photocatalytically active hydrophilicity of the anatase titanium dioxide (TiO2) nanoparticles coated onto commercially pure titanium discs presented significantly improved hydrophilicity after ultraviolet irradiation. As hydrophilicity has shown enhancement of osseointegration, the in vivo responses were of great interest. The aim of this study was to evaluate whether or not the photo-activated hydrophilicity generated at the time of implant placement has an effect on the longer healing periods for osseointegration. Materials and methodsPhotocatatytically active nanostructured TiO2 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. These P25-coated discs were irradiated with ultraviolet (UV) light for the test (+UV) group, and non-irradiated discs were prepared for the control (-UV) group. Both groups of discs were placed in the rabbits' tibiae. After 12weeks of healing period, histological analysis and gene expression analysis using real-time RT-PCR were performed. ResultsFrom the histological analyses, there were no specific differences between -UV and +UV groups. However, from the gene expression analysis, ALP, RUNX-2 and IL-10 were significantly upregulated for the +UV group compared with the -UV group. ConclusionsThe biologically enhancing effect to photocatalytically activated surfaces remained even after 12weeks of healing time in terms of genetic responses.
  • He, Wenxiao, 1985-, et al. (författare)
  • Osteogenesis-inducing calcium phosphate nanoparticle precursors applied to titanium surfaces
  • 2013
  • Ingår i: Biomedical Materials (Bristol). - 1748-6041. ; 8:3
  • Tidskriftsartikel (refereegranskat)abstract
    • This study investigated the effects of the morphology and physicochemical properties of calcium phosphate (CaP) nanoparticles on osteogenesis. Two types of CaP nanoparticles were compared, namely amorphous calcium phosphate (ACP) nano-spheres (diameter: 9-13 nm) and poorly crystalline apatite (PCA) nano-needles (30-50 nm x 2-4 nm) that closely resemble bone apatite. CaP particles were spin-coated onto titanium discs and implants; they were evaluated in cultured mouse calvarial osteoblasts, as well as after implantation in rabbit femurs. A significant dependence of CaP coatings was observed in osteoblast-related gene expression (Runx2, Colla1 and Spp1). Specifically, the PCA group presented an up-regulation of the osteospecific genes, while the ACP group suppressed the Runx2 and Colla1 expression when compared to blank titanium substrates. Both the ACP and PCA groups presented a more than three-fold increase of calcium deposition, as suggested by Alizarin red staining. The removal torque results implied a slight tendency in favour of the PCA group. Different forms of CaP nanostructures presented different biologic differences; the obtained information can be used to optimize surface coatings on biomaterials.
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