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- Chai, Wen Lin, et al.
(författare)
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Development of a novel model for the investigation of implant-soft tissue interface.
- 2010
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Ingår i: Journal of periodontology. - : Wiley. - 1943-3670 .- 0022-3492. ; 81:8, s. 1187-95
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In dental implant treatment, the long-term prognosis is dependent on the biologic seal formed by the soft tissue around the implant. The in vitro investigation of the implant-soft tissue interface is usually carried out using a monolayer cell-culture model that lacks a polarized-cell phenotype. This study developed a tissue-engineered three-dimensional oral mucosal model (3D OMM) to investigate the implant-soft tissue interface. METHODS: A 3D OMM was constructed using primary human oral keratinocytes and fibroblasts cultured on a skin-derived scaffold at an air-liquid interface. A titanium implant was inserted into the engineered oral mucosa and further cultured to establish epithelial attachment. The 3D OMM was characterized using basic histology and immunostaining for cytokeratin (CK) 10 and CK13. Histomorphometric analyses of the implant-soft tissue interface were carried out using a light-microscopy (LM) examination of ground sections and semi-thin sections as well as scanning electron microscopy (SEM). RESULTS: Immunohistochemistry analyses suggests that the engineered oral mucosa closely resembles the normal oral mucosa. The LM and SEM examinations reveal that the 3D OMM forms an epithelial attachment on the titanium surface. CONCLUSION: The 3D OMM provided mimicking peri-implant features as seen in an in vivo model and has the potential to be used as a relevant alternative model to assess implant-soft tissue interactions.
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- Grandfield, Kathryn, et al.
(författare)
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Visualizing biointerfaces in three dimensions : electron tomography of the bone-hydroxyapatite interface
- 2010
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Ingår i: Journal of the Royal Society Interface. - : The Royal Society. - 1742-5689 .- 1742-5662. ; 7:51, s. 1497-501
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Tidskriftsartikel (refereegranskat)abstract
- A positive interaction between human bone tissue and synthetics is crucial for the success of bone-regenerative materials. A greater understanding of the mechanisms governing bone-bonding is often gained via visualization of the bone-implant interface. Interfaces to bone have long been imaged with light, X-rays and electrons. Most of these techniques, however, only provide low-resolution or two-dimensional information. With the advances in modern day transmission electron microscopy, including new hardware and increased software computational speeds, the high-resolution visualization and analysis of three-dimensional structures is possible via electron tomography. We report, for the first time, a three-dimensional reconstruction of the interface between human bone and a hydroxyapatite implant using Z-contrast electron tomography. Viewing this structure in three dimensions enabled us to observe the nanometre differences in the orientation of hydroxyapatite crystals precipitated on the implant surface in vivo versus those in the collagen matrix of bone. Insight into the morphology of biointerfaces is considerably enhanced with three-dimensional techniques. In this regard, electron tomography may revolutionize the approach to high-resolution biointerface characterization.
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- Omar, Omar, et al.
(författare)
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Interfacial gene expression and stability of oxidized and machined titanium implants
- 2010
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Ingår i: European Association for Osseointegration 19th Annual Scientific Meeting, Glasgow, UK, 6-9 October, 2010.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In previous studies, combination of experimental model and gene expression analysis showed that from 3 hours to 6 days of implantation, significant differences in expression of genes denoting for cellular recruitment, inflammation, bone formation and bone resorption were seen at the interfaces of screw-shaped oxidized and machined titanium implants. It was concluded that the modulation of gene expression in favor of osteogenic differentiation and downregulation of the pro-inflammatory responses might explain the improved osseointegration of the oxidized implant surfaces. However, as a major condition, the developed bone-implant interface needs to be mechanically stable in order to fulfill the requirements of osseointegration The aim of the current study was to combine in vivo interfacial gene expression model with torque analysis in order to determine how molecular and cellular events taking place at the different titanium implants are related to the biomechanical properties of the interface. Anodically oxidized and machined titanium miniscrews were inserted in tibiae of 6 rats. Each rat received two oxidized implants in one tibia and two machined implants in the opposite tibia. After 28 days, the implants were removed using torque measuring equipment. The torque was registered and the implants completely removed and analyzed with quantitative polymerase chain reaction (n=12). Wilcoxon signed rank test was used to analyze the statistical differences of biomechanical and gene expression results between the two implant types. In addition, similar oxidized and machined titanium miniscrews were characterized topographically, chemically and ultrastructurally using profilometry, Auger electron microscopy and cross-sectioning electron microscopy, respectively. For chemical and topographical analyses, 3 implants from each type were analyzed. The measurements were made on flanks, tops, and valleys of two nonadjacent threads giving a total of 18 measurements for each implant type. Topographical comparisons were performed using one-way ANOVA followed by Bonferroni’s test. The biomechanical evaluation demonstrated 190% increase in torque values for the oxidized implants as compared to the machined ones. At the same time (28d), oxidized implants showed significantly higher expression of Runt-related transcription factor 1, osteocalcin, and tartrate resistant acid phosphatase. On the other hand higher expression of tumor necrosis factor-α and interleukin-1β was detected on the machined surfaces. Surface characterization procedures revealed major differences in the physico-chemical properties of the implant surfaces. In conclusion, the favorable cellular and molecular events at the oxidized implants were in parallel with significantly stronger bone anchorage during osseointegration
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- Palmquist, Anders, 1977, et al.
(författare)
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Biomechanical, Histological and Ultrastructural Analyses of Laser Micro- and Nano-structured Titanium Alloy Implants : A Study in Rabbit
- 2010
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Ingår i: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 92A:4, s. 1476-1486
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the biomechanical properties and ultrastructure of the bone response of partly laser-modified Ti6Al4V implants compared with turned, machined implants after 8 weeks in rabbit. The surface analyses performed with interference microscopy and electron microscopy showed increased surface topography with micro- and nano-sized surface features as well as increased oxide thickness of the modified surface. The biomechanical testing demonstrated a 270% increase in torque value for the surface modified implants compared with the control implants. Histological evaluation of ground sections of specimens subjected to biomechanical testing revealed ongoing bone formation and remodeling. A histological feature exclusively observed at the laser-modified surface was the presence of fracture in the mineralized bone rather than at the interface between the bone and implant. Transmission electron microscopy (TEM) was performed on Focused Ion Beam (FIB) prepared samples of the intact bone-implant interface, demonstrating a direct contact between nanocrystalline hydroxyapatite and the oxide of the laser-modified implant surface. In conclusion, laser-modified titanium alloy implants have significantly stronger bone anchorage compared with machined implants and show no adverse tissue reactions.
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- Palmquist, Anders, 1977, et al.
(författare)
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Liaison osseuse et propriétés biomécaniques améliorées par des modifications à léchelle micro- et nanoscopique d'une surface d'oxyde de titane traitée par laser
- 2010
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Ingår i: Implant. - 1254-2431. ; 16:3, s. 165-171
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the current article was to review the development of a novel concept based on the topological application of micro- and nanoscale surface features on titanium oxide surfaces in order to achieve bone bonding and increased stability of the bone-implant junction. The analysis consisted of removal torque measurements, qualitative and quantitative histology, and scanning and transmission electron microscopy in order to obtain a state-of-the-art characterization of osseointegration on the macro-, micro- and nanolevels. Short and long-term, experimental studies of partly laser-modified implants with micro- and nano-scale surface topographical features demonstrated a considerable increase in the biomechanical anchorage to bone. The results showed a significant increase in removal torque, a different fracture pattern, and ultrastructural and chemical coalescence between mineralized tissue and the nano-structured surface of the laser modified implant. Studies in soft tissues demonstrated biocompatibility, a degree of inflammation comparable to machined titanium and no adverse events. This surface modification is now in clinical use. The first clinical data shows that this new concept provides excellent short-term (1 year follow up) performance.
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