| 1. |
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| 2. |
- Omar, Omar, et al.
(författare)
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In vivo gene expression in response to anodically oxidized versus machined titanium implants.
- 2010
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Ingår i: Journal of biomedical materials research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 92:4, s. 1552-1566
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Tidskriftsartikel (refereegranskat)abstract
- A quantitative polymerase chain reaction technique (qPCR) in combination with scanning electron microscopy was applied for the evaluation of early gene expression response and cellular reactions close to titanium implants. Anodically oxidized and machined titanium miniscrews were inserted in rat tibiae. After 1, 3, and 6 days the implants were unscrewed and the surrounding bone was retrieved using trephines. Both the implants and bone were analyzed with qPCR. A greater amount of cells, as indicated with higher expression of 18S, was detected on the oxidized surface after 1 and 6 days. Significantly higher osteocalcin (at day 6), alkaline phosphatase (at days 3 and 6), and cathepsin K (at day 3) expression was demonstrated for the oxidized surface. Higher expression of tumor necrosis factor-alpha (at day 1) and interleukin-1beta (at days 1 and 6) was detected on the machined surfaces. SEM revealed a higher amount of mesenchymal-like cells on the oxidized surface. The results show that the rapid recruitment of mesenchymal cells, the rapid triggering of gene expression crucial for bone remodeling and the transient nature of inflammation, constitute biological mechanisms for osseointegration, and high implant stability associated with anodically oxidized implants. (c) 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2009.
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| 3. |
- Omar, Omar, et al.
(författare)
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Integrin and chemokine receptor gene expression in implant-adherent cells during early osseointegration.
- 2010
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Ingår i: Journal of materials science. Materials in medicine. - : Springer Science and Business Media LLC. - 1573-4838 .- 0957-4530. ; 21:3, s. 969-80
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms of early cellular recruitment and interaction to titanium implants are not well understood. The aim of this study was to investigate the expression of pro-inflammatory cytokines, chemokines and adhesion markers during the first 24 h of implantation. Anodically oxidized and machined titanium implants were inserted in rat tibia. After 3, 12, and 24 h the implants were unscrewed and analyzed with quantitative polymerase chain reaction. Immunohistochemistry and scanning electron microscopy revealed different cell types, morphology and adhesion at the two implant surfaces. A greater amount of cells, as indicated by higher expression of small subunit ribosomal RNA (18S), was detected on the oxidized surface. Higher expression of CXC chemokine receptor-4 (at 12 h) and integrins, alphav (at 12 h), beta1 (at 24 h) and beta2 (at 12 and 24 h) was detected at the oxidized surfaces. Significantly higher tumor necrosis factor-alpha (at 3 h) and interleukin-1beta (at 24 h) expression was demonstrated for the machined surface. It is concluded that material surface properties rapidly modulate the expression of receptors important for the recruitment and adhesion of cells which are crucial for the inflammatory and regenerative processes at implant surfaces in vivo.
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| 4. |
- 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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| 5. |
- Omar, Omar, et al.
(författare)
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The correlation between gene expression of proinflammatory markers and bone formation during osseointegration with titanium implants
- 2011
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612. ; 32:2, s. 374-86
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Tidskriftsartikel (refereegranskat)abstract
- An in vivo interfacial gene expression model combined with biomechanical analysis was used in order to determine the relationship between the molecular events taking place during osseointegration and the biomechanical stability of the implant. Anodically oxidized and machined, threaded titanium implants were characterized topographically, chemically and ultrastructurally. The implants were inserted in rat tibiae and the implant bone torsion stability was evaluated. After measurements, the implants were removed and analyzed with qPCR. Results showed an increase in the breakpoint torque of 140%, 170% and 190%, after 6, 14, and 28 days, respectively, at the oxidized implants as compared to the machined. Gene expression analysis revealed higher expression of runt related transcription factor-2 (Runx2) (after 28 d), osteocalcin (OC) and tartrate resistant acid phosphatase (TRAP) (after 6, 14 and 28 d) and cathepsin K (CATK) (after 6 and 14 d) at the oxidized implants. On the other hand, machined implants were associated with higher expression of tumor necrosis factor-α (TNF-α) (after 6 and 28 d) and interleukin-1β (IL-1β) (after 6, 14 and 28 d) compared to the oxidized implants. 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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| 6. |
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| 7. |
- Palmquist, Anders, 1977, et al.
(författare)
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Acute Inflammatory Response to Laser-Induced Micro- and Nano-Sized Titanium Surface Features.
- 2013
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Ingår i: Clinical implant dentistry and related research. - : Wiley. - 1708-8208 .- 1523-0899. ; 15:1, s. 96-104
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Tidskriftsartikel (refereegranskat)abstract
- Background: The inflammatory process induced by implant surfaces is an important component of the tissue response, where limited knowledge is available regarding the role of surface topography. With laser ablation, a combined micro- and nanoscale surfacemodification could be created, which have been shown to enhance bone growth and biomechanical stability in vivo. Purpose: The aim of this article was to evaluate the early in vivo inflammatory response to laser-modified titanium disks, with machined titanium disks and sham operation sites serving as controls. Materials and Methods: Circular disks were installed in a subcutaneous rat model for 24 and 72 hours, where the cell number, cell types, and cytokine levels were evaluated. Results: The results revealed that significantly fewer inflammatory cells (mononuclear and polymorphonuclear) were attracted to the sites with the laser-modified implants compared with the machined titanium implants. Similar concentrations of pro-inflammatory cytokines (TNF-a and MCP-1), together with slightly higher cell viability, were observed around the laser-modified surface compared with the machined surface. Conclusions: The results in the present study suggest that the combination of surface micro and nano features of the laser-treated surface contributes to the downregulation of early inflammatory events.
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| 8. |
- Rydén, Louise, 1975, et al.
(författare)
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Early inflammatory response in soft tissues induced by thin calcium phosphates.
- 2013
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Ingår i: Journal of biomedical materials research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 101A:9, s. 2712-2717
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Tidskriftsartikel (refereegranskat)abstract
- The inflammatory response to titanium and hydroxyapatite (HA)-coated titanium in living tissue is controlled by a number of humoral factors, of which monocyte chemoattractant protein-1 (MCP-1) has been specifically linked to the recruitment of monocytes. These cells subsequently mature into tissue-bound macrophages. Macrophages adhering to the proteins adsorbed at the implant surface play a pivotal role in initiating the rejection or integration of the foreign material. Despite this, little is known about the initial inflammatory events that occur in soft tissues following the implantation of titanium and HA-coated titanium implants. In this study, circular discs of commercially pure titanium (c.p. Ti) with either a thin crystalline HA coating or amorphous HA coating or uncoated were implanted subcutaneously into rats. The implants were retrieved after 24 and 72 h. The lactate dehydrogenase (LD) activity, DNA content, expression of MCP-1, interleukin-10 (IL-10), tumor necrosis factor α (TNF-α), as well as monocyte and polymorphonuclear granulocyte counts in the exudate surrounding the implants were analyzed. There were significantly higher DNA and LD levels around the titanium implants at 24 h compared with HA-coated titanium. A rapid decrease in MCP-1 levels was observed for all the implants over the period of observation. No statistically significant differences were found between the two HA-coated implants. Our results suggest a difference in the early soft-tissue response to HA-coated implants when compared with titanium implants, expressed as a downregulation of inflammatory cell recruitment. This suggests that thin HA coatings are promising surfaces for soft tissue applications.
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| 9. |
- Silva, Ingrid, et al.
(författare)
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Stability after maxillary segmentation for correction of anterior open bite: A cohort study of 33 cases.
- 2013
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Ingår i: Journal of Cranio-Maxillofacial Surgery. - : Elsevier BV. - 1010-5182 .- 1878-4119. ; 41:7
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this cohort study was to evaluate the stability after multi-segmentation of the maxilla for correction of anterior open bite deformities. A total of 33 patients who underwent segmented maxillary osteotomy between 1994 and 2006 were included in the study. Rigid fixation with plates and postsurgical intermaxillary fixation for 6 weeks was applied to each patient. All patients were then followed in a standardized examination procedure at months 6, 12, 18 and up to 30 months postoperatively. Vertical and horizontal relation of the incisors was measured both clinically and on cast models. The main finding was that statistically significant relapse was found vertically, whereas the horizontal relationship to the mandible was unchanged. The vertical relapses were predominantly seen in patients with severe open bite evident preoperatively.
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| 10. |
- Slotte, Christer, 1954, et al.
(författare)
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Gene Expression of Inflammation and Bone Healing in Peri-Implant Crevicular Fluid after Placement and Loading of Dental Implants. A Kinetic Clinical Pilot Study Using Quantitative Real-Time PCR.
- 2012
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Ingår i: Clinical implant dentistry and related research. - : Wiley. - 1708-8208 .- 1523-0899. ; 14:5, s. 723-736
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Early detection of healing complications after placement of dental implants is a pressing but elusive goal. This paper proposes a non-invasive diagnostic tool for monitoring healing- and peri-implant disease specific genes, complementary to clinical evaluations. Material and Methods: Eighteen partially edentulous patients were recruited to this pilot study. Three Brånemark TiUnite® implants/patient (Nobel Biocare) were placed in a one-stage procedure. Abutments with smooth or rough (TiUnite®) surface were placed. The test group (n=9) received fixed bridges (immediate loading), whereas the control group (n=9) implants were loaded 3 months after surgery. In addition to clinical measurements, crevicular fluid was collected using paper strips at the implant abutments 2, 14, 28, and 90 days postoperative. mRNA was extracted, purified, and converted to cDNA. Quantitative PCR assays for IL-1β, TNF-α, Osteocalcin (OC), Alkaline Phosphatase (ALP), Cathepsin K, Tartrate Resistant Acid Phosphatase, and 18S ribosomal RNA were designed and validated. Relative gene expression levels were calculated. Results: One implant was lost in the control group and three in the test group. In one test patient, one implant showed lowered stability after 2 to 4 weeks and was unloaded. Later implant stability improved which allowed for loading after 3 to 4 months. TNF-α and ALP most commonly showed correlation with clinical parameters followed by IL-1β and OC. The strongest correlation was found for TNF-α with clinical complications at 2 and 14 days (p=.01/r=-048, and p=.0004/r=-0.56, respectively; test and control groups together). In some cases, gene expression predicted clinical complications (TNF-α, ALP, CK). Conclusion: This study is based on samples from few individuals; still, some genes showed correlation with clinical findings. Further studies are needed to refine and optimize the sampling process, to find the appropriate panel, and to validate gene expression for monitoring implant healing.
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| 11. |
- Suska, Felicia, 1974, et al.
(författare)
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Enhancement of CRF-PEEK osseointegration by plasma-sprayed hydroxyapatite: A rabbit model.
- 2014
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Ingår i: Journal of biomaterials applications. - : SAGE Publications. - 1530-8022 .- 0885-3282. ; 29:2, s. 234-242
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Tidskriftsartikel (refereegranskat)abstract
- Carbon-fibre-reinforced polyether ether ketone (CFR-PEEK) exhibits excellent biomechanical properties as it has an elastic modulus similar to bone. However, CFR-PEEK displays inferior biocompatibility compared with titanium alloy and coating techniques are therefore of interest in order to improve integration. In this paper, the early biological response to CFR-PEEK implants, with and without hydroxyapatite coating, was investigated. Furthermore, a hydroxyapatite-coated titanium alloy reference served as a clinically relevant control. The study was conducted in a rabbit model, both in femur trabecular bone as well as in tibia cortical bone. The results demonstrated that an hydroxyapatite coating significantly enhances the bone response to PEEK implants invivo. Moreover, in cortical bone, hydroxyapatite-coated PEEK implants induced superior bone response compared with hydroxyapatite-coated Ti ones. These results suggest that hydroxyapatite-coated CFR-PEEK is a suitable material for invivo implantation.
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| 12. |
- Suska, Felicia, 1974, et al.
(författare)
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In vivo evaluation of noble metal coatings
- 2010
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Ingår i: Journal of Biomedical Materials Research Part B: Applied Biomaterials. - 1552-4981. ; 92B:1, s. 86-94
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Tidskriftsartikel (refereegranskat)abstract
- A nanotopographic noble metal (Ag, Au, Pd) coating has been applied on commercial urinary catheters and used in more than 80,000 patients, with good clinical results. We have previously evaluated the biocompatibility of different variations of this coating, showing high cellular viability and function in vitro. However, the reasons for good clinical and preclinical behavior are not known. This in vivo study aimed to investigate the soft tissue peri-implant reaction to five coatings with systematically altered noble metal ratios after 1, 3, and 21 days of implantation in rats. The results show that coatings of silver only, or silver with medium amounts of gold and low-medium palladium content were superior to other tested coatings. Such surfaces were during the first days after implantation associated with a decreased recruitment of inflammatory cells to implant close exudates, a lower percentage of neutrophils, higher cell viability, and lower production of monocyte chemoattractant protein-1 (MCP-1), compared to the other coatings and uncoated silicone (PDMS) control. In contrast, the addition of higher concentrations of gold and palladium to silver induced a thicker soft tissue capsule. Coatings with high concentration of palladium induced the thickest fibrouscapsule after 21 days of implantation. The study demonstrates that by varying the noble metal ratio at implant surfaces it is possible to modulate inflammation and fibrosis in soft tissue.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Svensson, Sara, 1981, et al.
(författare)
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Osseointegration of titanium with an antimicrobial nanostructured noble metal coating
- 2013
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Ingår i: Nanomedicine: Nanotechnology, Biology, and Medicine. - : Elsevier BV. - 1549-9634 .- 1549-9642. ; 9:7, s. 1048-1056
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Tidskriftsartikel (refereegranskat)abstract
- Nanometer scale surface features on implants and prostheses can potentially be used to enhance osseointegration and may also add further functionalities, such as infection resistance, to the implant. In this study, a nanostructured noble metal coating consisting of palladium, gold and silver, never previously used in bone applications, was applied to machined titanium screws to evaluate osseointegration after 6 and 12. weeks in rabbit tibiae and femurs. Infection resistance was confirmed by in vitro adhesion test. A qualitatively and quantitatively similar in vivo bone response was observed for the coated and uncoated control screws, using histology, histomorphometry and electron microscopy. The bone-implant interface analysis revealed an extensive bone formation and direct bone-implant contact. These results demonstrate that the nanostructured noble metal coating with antimicrobial properties promotes osseointegration and may therefore be used to add extra implant functionality in the form of increased resistance to infection without the use of antibiotics. From the Clinical Editor: The authors of this paper demonstrate that nanostructured noble metal coating of implants and prostheses used in orthopedic procedures promotes osseointegration and may be used to add extra implant functionality in the form of increased resistance to infection without the use of antibiotics.
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