| 1. |
- Barkarmo, Sargon, et al.
(författare)
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Nano-hydroxyapatite-coated PEEK implants : a pilot study in rabbit bone
- 2013
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Ingår i: Journal of Biomedical Materials Research. Part A. - : John Wiley & Sons. - 1549-3296 .- 1552-4965. ; 101A:2, s. 465-471
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Tidskriftsartikel (refereegranskat)abstract
- Osseointegration of surface-modified polyetheretherketone (PEEK) implants was studied in vivo. A total of 18 cylinder-shaped PEEK implants were inserted in the femurs of nine New Zealand rabbits; half were coated with nanocrystalline hydroxyapatite (nanoHA) and half were uncoated controls. Healing time was 6 weeks. Samples were retrieved with the implant and surrounding tissue, processed to cut and ground sections, and analyzed histomorphometrically. The implant surfaces were analyzed with optical interferometry, scanning electron microscopy (SEM), atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). NanoHA-coated PEEK surfaces had lower height deviation (Sa) than controls [mean ± SD: 0.41 μm (± 0.14) vs. 0.96 μm (± 0.28)]. SEM images showed the nanoHA crystals as a thin layer on the polymer surface. XPS analysis of the coated implants showed a Ca/P ratio of 1.67. Histomorphometry indicated that the nanoHA-coated implants had more bone-to-implant contact [16% (± 4.7) vs. 13% (± 9.3)] and more bone area [52% (± 9.5) vs. 45% (± 11.9)]. We found no difference between smooth nanoHA-coated cylinder-shaped PEEK implants and uncoated controls. However, higher mean bone-to-implant contact indicated better osseointegration in the coated implants than in the uncoated controls. The large number of lost implants was interpreted as a lack of primary stability due to implant design.
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| 2. |
- Cecchinato, Francesca, et al.
(författare)
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In vitro evaluation of human fetal osteoblast response to magnesium loaded mesoporous TiO2 coating.
- 2014
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Ingår i: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 102:11, s. 3862-3871
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Tidskriftsartikel (refereegranskat)abstract
- This work aimed to evaluate the in vitro response of Transfected Human Foetal Osteoblast (hFOB) cultured on a magnesium-loaded mesoporous TiO2 coating. The application of mesoporous films on titanium implant surfaces has shown very promising potential to enhance osseointegration. This type of coating has the ability to act as a framework to sustain bioactive agents and different drugs. Magnesium is the element that, after calcium, is the most frequently used to dope titanium implant surfaces, since it is crucial for protein formation, growth factor expression, and aids for bone mineral deposition on implant surfaces. Mesoporous TiO2 films with an average pore-size of 6 nm were produced by the evaporation-induced self-assembly method (EISA) and deposited onto titanium discs. Magnesium loading was performed by soaking the mesoporous TiO2 discs in a magnesium chloride solution. Surface characterization was conducted by SEM, XPS, optical interferometry, and AFM. Magnesium release profile was assessed at different time points using a Magnesium Detection kit. Cell morphology and spreading were observed with SEM. The cytoskeletal organization was stained with TRITC-conjugated Phalloidin and cell viability was evaluated through a mitochondrial colorimetric (MTT) assay. Furthermore, gene expression of bone markers and cell mineralization were analyzed by real time RT-PCR and alizarin-red staining, respectively. The surface chemical analysis by XPS revealed the successful adsorption of magnesium to the mesoporous coating. The AFM measurements revealed the presence of a nanostructured surface roughness. Osteoblasts viability and adhesion as well as the gene expression were unaffected by the addition of magnesium possibly due to its rapid burst release, however, were enhanced by the 3D nanostructure of the TiO2 layer.
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| 3. |
- Göransson, Anna, 1970, et al.
(författare)
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An in vitro comparison of possibly bioactive titanium implant surfaces.
- 2009
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Ingår i: Journal of Biomedical Materials Research Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 88:4, s. 1037-1047
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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. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.
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| 4. |
- Johansson, Pär, et al.
(författare)
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Biomechanical, histological, and computed X-ray tomographic analyses of hydroxyapatite coated PEEK implants in an extended healing model in rabbit
- 2018
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Ingår i: Journal of Biomedical Materials Research Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 106:5, s. 1440-1447
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Tidskriftsartikel (refereegranskat)abstract
- A nanosized hydroxyapatite (HA) modification on polyetheretherketone (PEEK) using a novel spin coating technique was investigated in a rabbit model. Spin coating technique creates a 20-40 nm thick layer of nanosized HA particles with similar shape, size, and crystallinity as human bone. Some implants were designed with a perforating hole in the apical region to mimic a fusion chamber of a spinal implant. The coating nano-structures were assessed using a scanning electron microscope. The in vivo response to HA-PEEK was compared to untreated PEEK with respect to removal torque, histomorphometry, and computed microtomography. The HA-coated and pure PEEK implants were inserted in the tibia and femur bone according to simple randomization. The rabbits were sacrificed 20 weeks after implantation. Removal torque analysis showed significantly higher values for HA-PEEK. Qualitative histological evaluation revealed an intimate contact between PEEK and the bone at the threads and perforated hole. Histomorphometric assessment showed higher bone-implant and bone area values for HA-PEEK but without statistical significance. The effect of the HA coating showed most prominent effect in the removal torque which may be correlated to an alteration in the bone quality around the HA-PEEK implants. (c) 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1440-1447, 2018.
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| 5. |
- Malekzadeh, Benoosh, et al.
(författare)
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Effects of locally administered insulin on bone formation in non-diabetic rats
- 2013
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Ingår i: Journal of Biomedical Materials Research. Part A. - : John Wiley & Sons. - 1549-3296 .- 1552-4965. ; 101A:1, s. 132-137
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Tidskriftsartikel (refereegranskat)abstract
- The possibility to control bone formation would be favorable in many areas of medicine, where bone defects is still a major challenge. Insulin has been suggested to exert both systemic and local anabolic effects in bone tissues. This raised the question whether locally administrated insulin could provide new therapeutic strategies for patients with local bone defects and impaired bone healing. The aim of this study was to evaluate bone formation in non-diabetic rats when local insulin is administered. This study differs from previous reports in two aspects: the use of non-diabetic animals and locally administered insulin. Twenty-four implants were inserted into 12 rats-one insulin-coated and one control-in each tibia for four weeks. Interferometry and histomorphometry were used to evaluate the surface topography and bone formation, respectively. Results demonstrated no significant changes in surface topography after insulin immobilization. Histomorphometry revealed significantly more bone around the insulin-coated implants (BA) (p = 0.005) and a similar amount of bone at the implant surface (BIC) (p = 0.117) compared with the controls. It was concluded that locally administered insulin from a titanium implant surface has the potential to increase bone formation not only in diabetic subjects but also in non-diabetic subjects.
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| 6. |
- Meirelles, Luiz, 1974, et al.
(författare)
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Bone reaction to nano hydroxyapatite modified titanium implants placed in a gap-healing model
- 2008
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Ingår i: Journal Biomedical MAterials Research - A. - : Wiley. - 1549-3296 .- 1552-4965. ; 87:3, s. 624-631
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Tidskriftsartikel (refereegranskat)abstract
- Nanohydroxyapatite materials show similar chemistry to the bone apatite and depending on the underlying topography and the method of preparation, the nanohydroxyapatite may simulate the specific arrangement of the crystals in bone. Hydroxyapatite (HA) and other CaP materials have been indicated in cases in which the optimal surgical fit is not achievable during surgery, and the HA surface properties may enhance bone filling of the defect area. In this study, very smooth electropolished titanium implants were used as substrata for nano-HA surface modification and as control. One of each implant (control and nano HA) was placed in the rabbit tibia in a surgical site 0.7 mm wider than the implant diameter, resulting in a gap of 0.35 mm on each implant side. Implant stability was ensured by a fixating plate fastened with two side screws. Topographical evaluation performed with an optical interferometer revealed the absence of microstructures on both implants and higher resolution evaluation with AFM showed similar nanoroughness parameters. Surface pores detected on the AFM measurements had similar diameter, depth, and surface porosity (%). Histological evaluation demonstrated similar bone formation for the nano HA and electropolished implants after 4 weeks of healing. These results do not support that nano-HA chemistry and nanotopography will enhance bone formation when placed in a gap-healing model. The very smooth surface may have prevented optimal activity of the material and future studies may evaluate the synergic effects of the surface chemistry, micro, and nanotopography, establishing the optimal parameters for each of them.
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| 7. |
- Meirelles, Luiz, 1974, et al.
(författare)
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Nano hydroxyapatite structures influence early bone formation
- 2008
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Ingår i: Journal Biomedical Materials Research - A. - : Wiley. - 1549-3296 .- 1552-4965. ; 87:2, s. 299-307
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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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| 8. |
- Schwartz Filho, Humberto Osvaldo, et al.
(författare)
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Titanium surfaces with nanotopography modulate cytokine production in cultured human gingival fibroblasts
- 2012
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Ingår i: Journal of Biomedical Materials Research. Part A. - : John Wiley & Sons. - 1549-3296 .- 1552-4965. ; 100:10, s. 2629-2636
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Tidskriftsartikel (refereegranskat)abstract
- Implant topography is an important factor that influences many cell types. To understand the role of topography in the inflammatory events, we evaluated the response of human gingival fibroblasts (HGFs) by the release pattern of cytokines. HGFs were cultured on Ti discs for 24 and 48 h. Four different surface treatments were used: machining method (turned), blasting followed by an acid-etching method (BAE), oxidative nanopatterning (ON) method, and an association of blasting followed by an acid-etching plus oxidative nanopatterning (BAE+ON) method. Extracellular levels of IL-6, IL-8, transforming growth factor beta (TGF-β), IL-4, and IL-10 were measured by enzyme-linked immunosorbant assay. Increased levels of IL-6 and IL-8 were observed in all surfaces after 24 h which decreased after 48 h. BAE, ON, and BAE+ON surfaces showed a reduction in IL-6 levels compared with the turned after 48 h (p < 0.05). On one hand, IL-8 production was lower in BAE+ON in comparison to the turned surface (p < 0.05). On the other hand, IL-4 showed increased levels with 48 h, which were significantly different between turned, BAE, and ON surfaces, but not with BAE+ON. Additionally, TGF-β and IL-10 production were not detected. This study indicates that nanotopography might be important in the modulation of the inflammatory response in cultured HGFs.
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| 9. |
- Westas, Emma, 1982, et al.
(författare)
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Bactericidal effect of photocatalytically-active nanostructured TiO2 surfaces on biofilms of the early oral colonizer, Streptococcus oralis
- 2017
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Ingår i: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 105:8, s. 2321-2328
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the photocatalytic bactericidal effect of nanostructured anatase-rich titanium dioxide (TiO2) on microbial biofilms. Commercially pure titanium discs were spin-coated with photocatalytic TiO2 nanoparticles (P25). Uncoated discs were used as control (CTRL). Half of the CTRL and half of the P25-coated surfaces were coated with purified saliva (SAL) to give four different groups (CTRL, CTRL + SAL, P25 and P25 + SAL). Streptococcus oralis were allowed to form biofilms on the discs for 18 h and non-adherent cells were rinsed off. Bacterial viability was assessed at time 0 with Live/Dead BacLight staining and epifluorescence microscopy. The remaining discs were divided into a non-UV group and UVA-irradiated (1UV) group (irradiation time, 6 or 24 h). Thereafter, viability was assessed as above. Viability at time 0 was high and no dead cells were seen on any of the surfaces, even after 24 h, in the absence of UVA. However, after 24 h of exposure, the proportion of viable cells was reduced by 40% on the P25 discs compared to 0 and 6 h, and this effect was enhanced with a salivary pellicle. Members of mixed species biofilms differ in their susceptibility to the bactericidal effect of the surfaces tested and further investigations are needed to optimize the conditions.
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| 10. |
- Westas, Emma, 1982, et al.
(författare)
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Using QCM-D to study the adhesion of human gingival fibroblasts on implant surfaces
- 2015
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Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 103:10, s. 3139-3147
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Tidskriftsartikel (refereegranskat)abstract
- Sealing the soft tissue-implant interface is one of the key issues in preventing transcutaneous implant-associated infections. A promising surface modification for improving osseointegration and possibly soft tissue integration is to coat the implant surface with hydroxyapatite (HA) nanoparticles. When new implant materials are developed, their ability to facilitate cell attachment and spreading are commonly investigated in vitro to establish their potential for good in vivo performance. However, commonly used techniques, such as microscopy methods, are time consuming, invasive, and subjective. This is the first study using quartz crystal microbalance with dissipation monitoring, where the real-time adhesion of biopsy-derived human gingival fibroblasts onto titanium and nanostructured HA was investigated. Experiments were performed for at least 16 h, and we found that cellular attachment and spreading kinetics can be followed in situ by observing the change in dissipation and frequency with time. Interestingly, a correlation between cell coverage and the magnitude of dissipation shift reached at the end of the experiment was found, but no such trend was observed for the frequency. Furthermore, the level of cell coverage was found to influence the cellular attachment and spreading behavior. No difference in cell response to the two surface types, Ti and nanostructured HA, was found.
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