| 1. |
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| 2. |
- Bos, R., et al.
(författare)
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Retention of bacteria on a substratum surface with micro-patterned hydrophobicity
- 2000
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Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 189:2, s. 311-315
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Tidskriftsartikel (refereegranskat)abstract
- Bacteria adhere to almost any surface, despite continuing arguments about the importance of physico-chemical properties of substratum surfaces, such as hydrophobicity and charge in biofilm formation. Nevertheless, in vivo biofilm formation on teeth and also on voice prostheses in laryngectomized patients is less on hydrophobic than on hydrophilic surfaces. With the aid of micro-patterned surfaces consisting of 10-mu m wide hydrophobic lines separated by 20-mu m wide hydrophilic spacings, we demonstrate here, For the first time in one and the same experiment, that bacteria do not have a strong preference for adhesion to hydrophobic or hydrophilic surfaces. Upon challenging the adhering bacteria, after deposition in a parallel plate flow chamber, with a high detachment force, however, bacteria were easily wiped-off hydrophobic lines, most notably when these lines were oriented parallel to the direction of flow. Adhering bacteria detached slightly less from the hydrophilic spacings in between, but preferentially accumulated adhering on the hydrophilic regions close to the interface between the hydrophilic spacings and hydrophobic lines. It is concluded that substratum hydrophobicity is a major determinant of bacterial retention while it hardly influences bacterial adhesion.
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| 3. |
- Denis, F. A., et al.
(författare)
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Protein adsorption on model surfaces with controlled nanotopography and chemistry
- 2002
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 18:3, s. 819-828
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the influence of substratum surface characteristics on protein adsorption processes, we have investigated the adsorption (adsorbed amount, supramolecular organization) of collagen on model substrata exhibiting controlled topography and surface chemistry. Substrata were prepared in two steps: (i) gold deposition onto silicon wafers (smooth substrata) and onto a support with nanoscale protrusions created by colloidal lithography (rough substrata); (ii) functionalization with CH3 (hydrophobic) and OH (hydrophilic) groups, using alkanethiol self-assembly. Atomic force microscopy (AFM) images were recorded under water, prior to and after collagen adsorption, and the images were analyzed quantitatively using two independent approaches. On smooth substrata, collagen formed a similar to6 nm thick, homogeneous layer with low roughness on hydrophilic surfaces, and a similar to20 nm thick layer exhibiting elongated aggregated structures on hydrophobic surfaces. Film thickness measurements (AFM) together with X-ray photoelectron spectroscopy (XPS) revealed larger adsorbed amounts on hydrophobic surfaces compared to hydrophilic ones. On rough substrata, the adsorbed amounts were similar to those found on smooth substrata; however, the collagen molecules no longer formed aggregated structures on the hydrophobic surfaces. It is concluded that while the adsorbed amount is only affected by the surface chemistry, the supramolecular organization of the adsorbed layer is controlled both by surface chemistry and topography. The approach presented here will have great value in biophysics for investigating bioadsorption and bioadhesion processes on substrata of defined surface properties.
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| 4. |
- Addi, Simon, et al.
(författare)
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Interface gap size of manually and CAD/CAM-manufactured ceramic inlays/onlays in vitro.
- 2002
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Ingår i: Journal of Dentistry. - 0300-5712 .- 1879-176X. ; 30:1, s. 53-58
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Tidskriftsartikel (refereegranskat)abstract
- Objectives : To determine the fit of ceramic inlays manufactured using a recently introduced CAD/CAM-system (Decim) and of two types of laboratory-made heat-pressed ceramics (IPS Empress and Opc). Materials and methods : Extracted human premolars were prepared to receive mesio-occlusodistal (MOD) ceramic inlays, for which 10 Denzir, 10 IPS Empress, and 10 Opc were fabricated. The Denzir restorations were produced by the manufacturer of the CAD/CAM-system, and the IPS Empress and Opc by student dental technicians. Before luting the internal fit on the diestone models and on the premolars was determined using replicas. After luting on the premolars with a resin composite the marginal and internal fit were measured. The values were analyzed statistically using ANOVA and Scheffe's test at a significance level of p<0.05. Results : Before luting there were no significant differences ( p>0.05) in the internal gap width between the three systems studied when placed on their matching diestone models. When placed on the premolars a significant difference ( p<0.01) in the internal fit was seen between Empress and Opc before luting, whereas there were no significant differences ( p>0.05) between Empress and Denzir and between Opc and Denzir. Between the diestone models and the premolars there were significant differences ( p<0.01) in the internal fit, except for IPS Empress. After luting there were no significant differences ( p>0.05) between IPS Empress and Denzir, whereas the marginal gap width was significantly wider ( p<0.001) for Opc than for IPS Empress and Denzir. The internal fit was significantly ( p<0.001) wider for Opc than for IPS Empress, whereas there were no significant differences ( p>0.05) between IPS Empress and Denzir or between Opc and Denzir. Conclusion : After luting there were only slight differences in the fit between the restorations fabricated using the three different manufacturing techniques and ceramics. Therefore, long-term follow-up studies are needed to assess the clinical significance of the slight differences between the three systems.
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| 5. |
- Persson-Sjögren, Solveig, et al.
(författare)
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Effects of dental materials on insulin release from isolated islets of Langerhans
- 2002
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Ingår i: Dental Materials. - 0109-5641 .- 1879-0097. ; 18:1, s. 20-25
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To investigate the possibility of using a whole organ model for evaluating the biological effects of dental restoration materials in vitro. Methods: The effect on insulin release of isolated Langerhans islets of a series of dental materials was examined. The islets were incubated for 1 h with extracts obtained from various dental materials and insulin was assayed radioimmunologically with crystalline mouse insulin. The results were analysed statistically using analysis of variance (ANOVA) and Scheffe's test at a significance level of p<0.05. Results: One dental ceramic, Vita VMK 95, significantly ( p<0.01) decreased the insulin release, whereas another dental ceramic, Empress ( p<0.01), a partly re-cast high-noble gold alloy ( p<0.001), a modified high-noble gold alloy ( p<0,05), and unalloyed copper ( p<0.001) significantly increased the release of insulin. Significance: The results demonstrate a new instance of examining the biological effects of dental restoration materials. The method provides information about the effect of different materials on organ level in vitro that can complement other in vitro tests.
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| 6. |
- Sjögren, Göran, et al.
(författare)
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Cytotoxicity of dental alloys, metals, and ceramics assessed by millipore filter, agar overlay, and MTT tests.
- 2002
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Ingår i: The Journal of Prosthetic Dentistry. - : Elsevier BV. - 0022-3913. ; 84:2, s. 229-236
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Tidskriftsartikel (refereegranskat)abstract
- Statement of Problem: Biocompatibility of dental materials is dependent on the release of elements from the materials. In addition, the composition, pretreatment, and handling of the materials influence the element release. Purpose: This study evaluated the cytotoxicity of dental alloys, metals, and ceramics, with specific emphasis on the effects of altering the composition and the pretreatment. Material and Methods: By using cells from a mouse fibroblast cell line and the agar overlay test, Millipore filter test, and MTT test, cytotoxicity of various metals, metal alloys, and ceramics for dental restoration were studied. Effects of altering the composition of a high noble gold alloy and of pretreatment of a ceramic-bonding alloy were also studied. In addition, the release of elements into the cell culture medium by the materials studied was measured using an inductively coupled plasma optical emission spectrophotometer. The results of the MTT test were analyzed statistically using ANOVA and Scheffé test at a significance level of P<.05. Results: Specimens manufactured from materials intended for dental restorations and handled in accordance with the manufacturers’ instructions were ranked from “noncytotoxic” to “mildly cytotoxic” according to the agar overlay and Millipore filter tests. For the MTT test, no significant differences were observed between these materials and controls, with the exception of JS C-gold and unalloyed titanium. The modified materials were ranked from “mildly cytotoxic” to “moderately cytotoxic” in the agar overlay and Millipore filter tests and from “noncytotoxic” to “moderately cytotoxic” in the MTT test. Thus, cytotoxicity was related to the alloy composition and treatment. The release of Cu and Zn seemed to be important for the cytotoxic effect. Conclusion: Alterations in the composition and the pretreatment can greatly influence the cytotoxicity, and the results stress the importance of carefully following the manufacturers’ instructions when handling dental materials.
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| 7. |
- Vasara, Anna I, et al.
(författare)
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Subchondral bone reaction associated with chondral defect and attempted cartilage repair in goats.
- 2004
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Ingår i: Calcified tissue international. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 74:1, s. 107-14
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Tidskriftsartikel (refereegranskat)abstract
- Repair of cartilage damage with autologous chondrocyte transplantation (ACT) has become popular in clinical use during the past few years. Although clinical results have mostly been successful, several unanswered questions remain regarding the biological mechanism of the repair process. The aim of this study was to develop a goat model for ACT. The repair was not successful due to the graft delamination, but we characterize the subchondral changes seen after the procedure. A chondral lesion was created in 14 goat knees, operated on 1 month later with ACT, and covered with periosteum or a bioabsorbable poly-L/D-lactide scaffold. After 3 months, only two of the five lesions repaired with ACT showed partly hyaline-like repair tissue, and all lesions (n = 4) with the scaffold failed. Even though the lesions did not extend through the calcified cartilage, the bone volume and collagen organization of bone structure were decreased when assessed by quantitative polarized light microscopy. There was a significant loss of bone matrix and distortion of the trabecular structure of subchondral bone, which extended several millimeters into the bone. The subchondral bone demonstrated strong hyaluronan staining in the bone marrow and cartilaginous areas with signs of endochondral ossification, suggesting structural remodeling of the bone. The goat model used here proved not to be an optimal model for ACT. The changes in subchondral bone may alter the biomechanical properties of the subchondral plate and thus the long-term survival of the repair tissue after ACT.
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| 8. |
- Kovács, Anikó, 1961, et al.
(författare)
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Immunohistochemical examination of P-cadherin in bullous and acantholytic skin diseases.
- 2004
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Ingår i: Acta dermato-venereologica. - : Medical Journals Sweden AB. - 0001-5555. ; 84:2, s. 116-9
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Tidskriftsartikel (refereegranskat)abstract
- Autoimmune blistering diseases (pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, dermatitis herpetiformis) and certain genodermatoses with acantholysis (Darier-disease, Hailey-Hailey disease) have different aetiological factors, but all result in bulla formation and/or in acantholysis. Cadherins are Ca++-dependent cell-cell adhesion molecules which play an important role in the cellular connection between normal cells. P-cadherin is involved in the selective adhesion of epidermal cells, and is expressed only on the surfaces of the two basal layers. We examined the expression of P-cadherin in some autoimmune bullous skin diseases and Darier's disease using immunohistochemistry and found P-cadherin to be strongly upregulated. We believe the upregulation is compensatory to the primary pathophysiological events in the various bullous dermatoses.
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| 9. |
- Eriksson, Cecilia, 1966
(författare)
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Interactions between whole blood and TiO₂ surfaces with focus on adhesion and activation of PMN granulocytes
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Foreign materials come in contact with the human body more and more frequently. The surgical procedure of inserting an implant into the body will cause bleeding, evoke an inflammatory response and initiate a healing process, ultimately leading to acceptance or rejection of the material. The implant will first encounter blood, and the importance of this first contact on the future fate of the material is largely unknown. Titanium is a biomaterial used in bone-anchored implants. It is known for its high biocompatibility, but the reason for the successful use of this material is only partly known. The oxide covering titanium is thought to be one factor influencing the biological response. The topography and wettability of the material are other influential factors.In this thesis the contact between whole blood and modified titanium surfaces was studied. The titanium surfaces differed with respect to surface roughness, wettability, and thickness of the surface oxide. The adsorption of plasma proteins and the adhesion and activation of platelets and leukocytes were investigated with focus on PMN granulocyte function.The results showed that a sequence of events take place on a titanium surface in contact with blood. Adsorption of proteins was detected after 5 seconds. After 5 seconds platelets had adhered to the surface and were activated after 4-8 minutes. It took approximately 8 minutes before PMN granulocytes adhered to the surface and about 30 minutes before they were in a primed state. Activation of platelets and priming of PMN granulocytes were more influenced by changes in surface roughness of titanium than of changes in oxide thickness. The cells were more activated/primed on rough surfaces than on smooth surfaces. The response of PMN granulocytes to hydrophilic and hydrophobic TiO2 surfaces showed differences in both adhesion mechanism and receptor expression during the first hour of contact between metal and blood. On hydrophilic titanium the cells adhered in a FcgIII receptor dependent manner and underwent transient priming on the surface. On hydrophobic titanium a platelet mediated adhesion via PSGL-1 was implicated and the priming was not transient. Contact with the titanium surfaces did not induce a respiratory burst from the PMN granulocytes and did not impair their ability to mount a respiratory burst upon stimulation.In conclusion, this thesis shows that the PMN granulocyte response to titanium is sensitive to changes in both surface structure and wettability.
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| 10. |
- Røkkum, Magne, 1953
(författare)
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On late complications with HA coated hip arthroplasties
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 100 hips in 86 patients were operated with a total hip arthroplasty entirely coated with a 155±35 µm thick HA coating, and included in a clinical and radiological follow-up study. The female/male ratio was 75/25, and the mean age was 56 years (32-73). Early clinical results were excellent, especially pain relief. No thigh pain was found. Radiologically, bone formation adjacent to the components as well as periprosthetic bone remodelling developed in all hips. Radiologically defined direct bone-implant contact averaged 94% or more in all components at five years. Proximal lines developed along 82 of 93 stems at seven to nine years. Five radiologically well-integrated and painless cups in five females loosened with symptoms starting 3.8 to 5.5 years postoperatively. Macroscopically, almost no HA was left on the removed components. Accelerating polyethylene wear was found, necessitating reoperations of 18 hips after 5.2 to 8.3 years, whereas six hips were pending for revision. Radiological osteolysis was found in 66 hips. In seven of 17 hips reoperated for polyethylene wear without wear-through of the inlay, metalosis of the soft tissue was found. Matting of the stainless steel heads was seen. All reoperations revealed disappearance of HA coating from the surfaces of the stems that were uncovered with bone. Twenty hips with the same stem were reoperated after 2.0 to 7.5 (mean 5.5) years because of polyethylene wear (10), acetabular loosening (7), instability (2), and infection (1). Biopsies including bone and soft tissue were obtained from the proximal femur adjacent to the medial or anterior aspect of the stem. Ten well fixed HA coated cups were removed with adjacent tissue at reoperations after 0.3 to 5.8 (mean 3.3) years because of infection (5), polyethylene wear (3), and instability (2). Histological examination demonstrated that fixation of the implants took place by bone formation directly on the HA coating, coalescing with original bone. The threads as well as the corresponding outfolded mirror images contained about 50% bone. The metal interface of the cups and the calcar biopsies contained just more than 50% HA. In the cups, the resulting metal-tissue interface included significantly more soft tissue than bone, and the total implant-tissue interface was nearly equally shared between bone and soft tissue. Great variations were seen. The mean thicknesses of the remaining HA coating in the calcar biopsies, an unused cup, and the retrieved cups were 148 mm, 112 µm, and 97 µm, respectively. HA degradation was seen in all hips, typically resulting in the disintegration of complete segments of the coating, apparently being replaced by soft tissue and bone. Multinucleated giant cells and a great number of macrophages were seen, the latter often containing HA remnants. In the calcar biopsies, osteoid-like tissue, bone and soft tissue were observed between the surface and the HA coating. Bone resorption associated with the presence of metal and polyethylene particles undermined the HA coat, resulting in the liberation of large flakes of HA with free access to the joint. The study indicated that HA particles released from coating adjacent to the joint caused third body wear in the articulation.
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| 11. |
- Eriksson, Cecilia, et al.
(författare)
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Interactions between human whole blood and modified TiO2-surfaces : Influence of surface topography and oxide thickness on leukocyte adhesion and activation
- 2001
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Ingår i: Biomaterials. - : Elsevier. - 0142-9612 .- 1878-5905. ; 22:14, s. 1987-1996
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Tidskriftsartikel (refereegranskat)abstract
- An in vitro model (Nygren et al., J Lab Clin Med 129 (1997) 35-46) was used to investigate interactions between leukocytes and four modified TiO2-surfaces. Surface topography was measured using scanning electron microscopy and optical profilometry while Auger electron spectroscopy was used to determine surface composition and oxide thickness. The surfaces were either smooth or rough with either thin or thick oxides. All surfaces consisted of TiO2 covered by a carbonaceous layer. The surfaces were incubated with capillary blood for time periods of between 8 min and 32h. Immunofluorescence techniques together with computer aided image analysis and chemiluminescence technique were used to detect cell adhesion, expression of adhesion receptors and the zymosan-stimulated respiratory burst response. Leukocyte adhesion to the surfaces increased during the first hours of blood-material contact and then decreased. Polymorphonuclear granulocytes were the dominating leukocytes on all surfaces followed by monocytes. Cells adhering to rough surfaces had higher normalized expression of adhesive receptors than cells on smooth surfaces. Maximum respiratory burst response occurred earlier on the smooth than on the rough surfaces. In conclusion, topography had a greater impact than oxide thickness on most cellular reactions investigated, but the latter often had a dampening effect on the responses. (C) 2001 Elsevier Science Ltd. All rights reserved.
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| 12. |
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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. |
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| 18. |
- Hallgren Höstner, Carin, 1971
(författare)
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On the bone response to different implant textures. A 3D analysis of roughness, wavelength and surface pattern of experimental implants
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- PurposeThe purpose of the present thesis was to investigate the bone response to different isotropic, anisotropic and organised surface patterns.Material and methodsImplant surfaces have been modified with different techniques (abrasive blasting, turning, milling, photolithography or laser ablation). Turned implants were used as controls in all of the studies. The surface topographies have been characterised visually and numerically using instruments appropriate to the study (Mechanical Stylus Profilometer, Confocal Laser Scanning Profilometer and/or Atomic Force Microscopy).Five studies were undertaken using two implant designs; cylinders and screws. In studies I, IV and V a total of 160 commercially available threaded implants were used. In study II, 54 microimplants were used, and in study III 40 cylinders. All implants were produced from commercially pure (c. p.) titanium grade I or II. In total 27 human patients and 50 New Zealand White rabbits have been involved.After a healing period of 12 weeks the rabbits were sacrificed and the implants were evaluated with resonance frequency analysis (2 studies), peak removal torque (3 studies), pull-out (1 study) and histomorphometry. The human implants were evaluated with histomorphometry after a mean healing time of 6.3 months in the maxillae and 3.9 months in the mandibles.ResultsThe results indicate that the influence of waviness in the surface topography of implants is of less importance than the surface roughness. It also seems that an anisotropic surface is superior to an isotropic surface for bone response to an implant surface.ConclusionA blasted surface, which has a surface with no dominant pattern, seems to be preferable to an anisotropic surface or a surface with a chequered pattern.Increasing the average wavelength from 10 µm to approximately 40 µm did not improve implant incorporation in bone.
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| 19. |
- Jansson, E, et al.
(författare)
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On the formation of fibrous capsule and fluid space around machined and porous blood plasma clot coated titanium.
- 2001
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Ingår i: Journal of materials science. Materials in medicine. - 0957-4530. ; 12:10-12, s. 1019-24
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Tidskriftsartikel (refereegranskat)abstract
- Machined and machined submicron porous titanium, with and without a thin blood plasma coating (100 nm), were implanted for 7 or 28 days in subcutaneous pockets on the back of the rat. After explantation the specimens were analyzed by light microscopy with respect to thickness of the fibrous capsule, the fluid space width between implants and fibrous capsule, and formation of blood vessels. The results at 7 days indicate a thinnest fluid space for the plasma clot coated porous titanium surface, and the spaces vanished at the light microscopic level after 28 days outside all the analyzed surfaces. The thickness of the fibrous capsule increased outside the different surfaces at 7-28 days, and in this respect no significant differences were observed between the different surfaces at any time. Analysis of neovascularization showed that the number of vessels and proportion of vessels in the fibrous capsule increased with time at all surfaces, except machined Ti where the number instead decreased from 7 to 28 days. The average distance between the blood vessels and the fluid space increased with time for all types of surfaces. The results in the present study indicate that the healing process around titanium can be modulated by porosity and thin pre-prepared plasma coatings.
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| 20. |
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| 21. |
- Källtorp, Mia, et al.
(författare)
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Analysis of rat plasma proteins desorbed from gold and methyl- and hydroxyl-terminated alkane thiols on gold surfaces.
- 2000
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Ingår i: Journal of materials science. Materials in medicine. - 0957-4530 .- 1573-4838. ; 11:3, s. 191-9
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Tidskriftsartikel (refereegranskat)abstract
- It is believed that adsorbed blood or plasma components, such as water, peptides, carbohydrates and proteins, determine key events in the concomitant inflammatory tissue response close to implants. The aim of the present study was to develop a procedure for the collection and analysis of minor amounts of proteins bound to solid metal implant surfaces. The combination of a sodium dodecyl sulfate washing method coupled with a polyacylamide gel electrophoretic protein separation technique (SDS-PAGE), Western blot and image analysis enabled the desorption, identification and semiquantification of specific proteins. The analyzed proteins were albumin, immunoglobulin G, fibrinogen and fibronectin. Concentration procedures of proteins were not required with this method despite the small area of the test surfaces. The plasma proteins were adsorbed to pure gold and hydroxylated and methylated gold surfaces, which elicit different tissue responses in vivo and plasma protein adsorption patterns in vitro. The image analysis revealed that the pure gold surfaces adsorbed the largest amount of total and specific proteins. This is in accordance with previous ellipsometry/antibody experiments in vitro. Further, the principles described for the protein analysis can be applied on implant surfaces ex vivo.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
- Mohammadi, Sham, 1960
(författare)
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On the tissue response to hafnium, titanium and thin calcium phosphate coatings
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Titanium (Ti) is the gold standard material for load-bearing implants. Although high success rates have been reported for Ti implants, failures do occur. Alternative materials/surface modifications might further improve the performances of Ti implants, particularly in situations with non-optimal local tissue conditions. Hafnium (Hf) is a metal closely related to titanium, but harder and its biocompatibility has not been evaluated. Calcium phosphate (CaP) coatings have been suggested to speed up bone healing. Despite that various types of CaP coatings have been used, evidence of their long-term behaviour and clinical superiority is still lacking. Aims: To evaluate the biological performance of Hf and thin magnetron sputtered CaP coatings with different properties in comparison with commercially pure (cp) Ti implant. Materials and Methods: Forty-two plugs and 36 screw-shaped implants of Hf and Ti were inserted in the abdominal wall of 21 rats for 8 days, 6 and 12 weeks, and in the cortical bone of 18 rabbits for 6, 12 and 24 weeks. In addition, 800 implants of noncoated titanium and magnetron sputtered thin CaP coatings with different thicknesses (100 nm and 2.0 µm), and crystallinity, were inserted in the cortical and trabecular bone of 100 rabbits for 1, 3, 6 weeks and 9 months. The implant surfaces were characterized using SEM, stylus profilometry, TopScan 3D, XRD, ICP-OES, and FTIR-ATR. The biological evaluation (fibrous capsule thickness and presence of inflammatory cells (in rats), and bone contact and bone area (in rabbits) was performed using light microscopy. Results: Hf showed to have a smoother (Sa=0.43-0.57 µm) surface than Ti (Sa=0.75 µm). The surface topography (Sa) of noncoated and CaP coatings varied in the range of 0.3-1.2 µm. The heat treatment of the coatings increased the degree of crystallinity of the coatings. The Ca/P ratio was 1.665 and the coatings showed absorption bands characteristic for hydroxyapatite. No significant differences were observed between Hf and Ti in neither implantation sites. After 6 weeks and 9 months, both crystalline calcium phosphate coatings had significantly higher bone contact than noncoated and amorphous CaP in both bone types. Noncoated Ti and both amorphous CaP coatings showed significantly higher bone area in their threads in both implantation sites. Summary and Conclusions: Hf showed a biocompatibility comparable to Ti. Hf might be an interesting metal as load-bearing implant, when a harder metal than Ti is desired. The 100 nm thin crystalline CaP coating induced an improved early bone apposition/bone contact that was maintained over a long time without inducing adverse inflammatory bone reaction. Submicron crystalline CaP coating may be an interesting surface modification since it adds bioactive property to the bioinert Ti. Clinical trials are needed to assess the clinical efficacy of such coatings.
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| 27. |
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| 28. |
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| 29. |
- Slotte, Christer, 1954
(författare)
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On surgical techniques to increase bone density and volume. Studies in the rat and the rabbit
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND. Various techniques of surgical intervention have been suggested to promote bone densityand volume; however, the predictability of such techniques is not always sufficiently supported by preclinicalevaluations.AIM. The general aim of the present thesis was to evaluate some surgical techniques claimed to increasebone volume and density and thereby improve implant retention and survival. In particular, the aims were toinvestigate the effect of cortical perforations of tibial, maxillary, and calvarial bone alone or in conjunctionwith a) titanium implants, b) guided bone augmentation (GBA) barriers, or c) GBA barriers combined withgrafting materials. In addition, the histologic characteristics of untreated calvarial bone were studied withspecial emphasis on vessel topography.MATERIALS AND METHODS. In study I, the effect of cortical perforations in the tibia and the maxilla wasevaluated in the rabbit, and the healing response in the two bones was compared. In study II, the effect ofsurgical intervention in the rabbit maxilla 4 weeks prior to implant placement was evaluated and comparedwith the effect of the implant placement per se. In study III, a rat calvarial model was used to study the effectof bovine bone mineral (BBM) placement as an adjunct to a silicone GBA barrier. In study IV, the impact ofcortical perforations in the rabbit calvaria contiguous to a titanium GBA barrier was evaluated. In study V,placement of autogeneic bone or BBM combined with a titanium GBA barrier was studied in a rabbit calvarialmodel. In study VI, vessel topography and bone density were studied in untreated rabbit calvaria.RESULTS. As observed 8 weeks postoperatively, cortical perforation resulted in significant bone densityincrease in the rabbit maxilla while no significant changes were found in the tibia. Implant placementsignificantly increased bone density while surgical intervention 4 weeks prior to implant placement did notfurther increase bone density or bone-implant contact. Cortical perforations were not found to promote boneaugmentation in the rabbit GBA model. Similar amounts of bone tissue and mineralized bone were found withthe adjunctive placement of autogeneic bone or BBM in the rabbit GBA model. In both the rat and the rabbitGBA models, the adjunctive placement of BBM significantly increased augmented bone tissue volumecompared to placement of barriers only. In the rabbit model, the addition of BBM was found to promotesignificantly more mineralized bone than placement of a barrier only. In the rat model, on the contrary,placement of the silicone barrier alone promoted more mineralized bone than with the addition of BBM. Theproportions of cortical, trabecular, and marrow areas found in the right and left untreated parietal bones weresimilar, as were the number and width of natural hollow connections in the cortical plates and the distributionof vessels. A similar number of these hollow connections was found in untreated and GBA-treated parietalbone.CONCLUSIONS. The different bone response to cortical perforations in the tibia and maxilla emphasizesthe importance of choice of experimental sites in bone/implant studies. Pre-implant surgical intervention doesnot seem to promote titanium implant incorporation in rabbit jawbone. The reason why cortical perforations didnot promote augmentation or bone density in the calvarial GBA model might be related to the presence of thenatural hollow connections in the cortical plates. Placement of particulated autogeneic bone or BBMsignificantly promoted bone augmentation in GBA. BBM promoted as much bone as autogeneic bone inconjunction with a stable, titanium GBA barrier. The lack of promotive effect of BBM on the formation ofmineralized bone in the rat GBA model might be because of ingrowth of soft tissue from the sagittal sutureinterfering with the GBA-site. Since the symmetry of the large vessel topography and the histomorphometricparameters assessed was high between the left and right parietal bones, the bilateral use of the parietal bones issuggested to be reliable in experimental GBA models regarding blood supply and bone quality.
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| 30. |
- Stenfelt, Stefan, 1969, et al.
(författare)
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A bone-anchored hearing aid for patients with pure sensorineural hearing impairment: a pilot study.
- 2000
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Ingår i: Scandinavian audiology. - : TAYLOR and FRANCIS AS. - 0105-0397 .- 1940-2872. ; 29:3, s. 175-85
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Tidskriftsartikel (refereegranskat)abstract
- This pilot study assesses the potential benefits of an optimized bone-anchored hearing aid (BAHA) for patients with a mild to moderate pure sensorineural high frequency hearing impairment. The evaluation was conducted with eight first-time hearing aid users by means of psycho-acoustic sound field measurements and a questionnaire on subjective experience; all of the patients benefited from the BAHA. On average, the eight patients showed improvement in PTA threshold of 3.4 dB and in speech intelligibility in noise of 14%. Seven of the subjects, also fitted with present standard air conduction hearing aids (ACHA) found the ACHA thresholds to be improved more than the BAHA ones. In speech tests, the ACHA was only slightly better; these patients chose between their different hearing aids according to the sound environment. Although the BAHA was preferred for wearing and sound comfort, it cannot be used as the sole aid for patients with pure sensorineural impairment.
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| 31. |
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| 32. |
- Suska, Felicia, 1974, et al.
(författare)
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In vivo/ex vivo cellular interactions with titanium and copper.
- 2001
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Ingår i: Journal of materials science. Materials in medicine. - 0957-4530 .- 1573-4838. ; 12:10-12, s. 939-44
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Tidskriftsartikel (refereegranskat)abstract
- Machined, commercially pure titanium (Ti) disks were coated with approximately 400 nm copper (Cu) by physical vapor deposition or left uncoated. The kinetics of inflammatory cell recruitment, distribution and viability was evaluated around Ti, Cu, and in sham sites after 1, 3, 12, 18, 24, and 48 h in a rat subcutaneous (s.c.) model. Further analysis of the cells on implant surfaces was performed by ex vivo incubation of the disks. Ti and Cu stimulated an increased recruitment of inflammatory cells in comparison with sham sites. A markedly higher amount of cells, predominantly polymorpho-nuclear granulocytes (PMN), was detected around Cu after 18 h and onwards. More cells were found at the implant surfaces than in the surrounding exudates after 18 h. The total amount of lactate dehydrogenase (LDH), an indicator of plasma membrane injury, was higher in Cu exudates after 18 h in comparison with Ti and sham. In contrast, no differences in the proportion of dead cells (trypan blue dye uptake) were detected in the exudates. Further, LDH levels were higher around Ti than Cu during the initial 18 h of ex vivo incubation. The results of this study indicate that the early inflammatory process associated with a cytotoxic material in soft tissues is largely attributed to the induction of a markedly strong and prolonged chemotactic response. In contrast, this process is characterized by a higher amount of inflammatory cells around a biocompatible material than in sham sites, but with a transient course and total LDH similar to sham sites.
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