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- Olofsson, Johanna, 1981-, et al.
(författare)
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Evaluation of silicon nitride as a wear resistant and resorbable alternative for total joint replacement
- 2012
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Ingår i: Biomatter. - : Landes Bioscience. - 2159-2527 .- 2159-2535. ; 2:2, s. 94-102
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Tidskriftsartikel (refereegranskat)abstract
- Many of the failures of total joint replacements are related to tribology, i.e., wear of the cup, head and liner. Accumulation of wear particles at the implants can be linked to osteolysis which leads to bone loss and in the end aseptic implant loosening. Therefore it is highly desirable to reduce the generation of wear particles from the implant surfaces.Silicon nitride (Si3N4) has shown to be biocompatible and have a low wear rate when sliding against itself and is therefore a good candidate as a hip joint material. Furthermore, wear particles of Si3N4 are predicted to slowly dissolve in polar liquids and they therefore have the potential to be resorbed in vivo, potentially reducing the risk for aseptic loosening.In this study, it was shown that α-Si3N4-powder dissolves in PBS. Adsorption of blood plasma indicated a good acceptance of Si3N4 in the body with relatively low immune response. Si3N4 sliding against Si3N4showed low wear rates both in bovine serum and PBS compared with the other tested wear couples. Tribofilms were built up on the Si3N4 surfaces both in PBS and in bovine serum, controlling the friction and wear characteristics.
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| 5. |
- Persson, Cecilia, et al.
(författare)
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Premixed calcium silicate cement for endodontic applications
- 2011
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Ingår i: Biomatter. - : Informa UK Limited. - 2159-2527 .- 2159-2535. ; 1:1, s. 76-80
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Tidskriftsartikel (refereegranskat)abstract
- Calcium silicate-based materials (also called MTA) are increasingly being used in endodontic applications. However, the handling properties of MTA are not optimal when it comes to injectability and cohesion. Premixing the cements using glycerol avoids these issues. However, there is a lack of data on the effect of common cement variables on important properties of premixed cements for endodontic applications. In this study, the effects of liquid-to-powder ratio, amount of radiopacifier and amount of calcium sulfate (added to control the setting time) were screened using a statistical model. In the second part of the study, the liquid-to-powder ratio was optimized for cements containing three different amounts of radiopacifier. Finally, the effect of using glycerol rather than water was evaluated in terms of radiopacity. The setting time was found to increase with the amount of radiopacifier when the liquid-to-powder ratio was fixed. This was likely due to the higher density of the radiopacifier in comparison to the calcium silicate, which gave a higher liquid-to-powder ratio in terms of volume. Using glycerol rather than water to mix the cements led to a decrease in radiopacity of the cement. In conclusion, we were able to produce premixed calcium silicate cements with acceptable properties for use in endodontic applications.
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| 6. |
- Persson, Cecilia, et al.
(författare)
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The effect of oligo(trimethylene carbonate) addition on the stiffness of acrylic bone cement
- 2016
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Ingår i: Biomatter. - : Informa UK Limited. - 2159-2527 .- 2159-2535. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- With the increasing elderly population an increase in the number of bony fractures associated toage-related diseases such as osteoporosis also follows. The relatively high stiffness of the acrylicbone cements used in these patients has been suggested to give raise to a suboptimal loaddistribution surrounding the cementin vivo, and hence contribute to clinical complications, such asadditional fractures. The aim of this study was to develop a low-modulus bone cement, based oncurrently used, commercially available poly(methyl methacrylate) (PMMA) cements forvertebroplasty. To this end, acrylate end-functionalized oligo(trimethylene carbonate) (oTMC) wasincorporated into the cements, and the resulting compressive mechanical properties wereevaluated, as well as the cytotoxic and handling properties of selected formulations. Sixteenwt%oTMC was needed in the vertebroplastic cement Osteopal V to achieve an elastic modulus of1063 MPa (SD 74), which gave a corresponding compressive strength of 46.1 MPa (SD 1.9). Cementextracts taken at 1 and 12 hours gave a reduced MG-63 cell viability in most cases, while extractstaken at 24 hours had no significant effect on cell behavior. The modification also gave an increasein setting time, from 14.7 min (SD 1.7) to 18.0 min (SD 0.9), and a decrease in maximumpolymerization temperature, from 41.5C (SD 3.4) to 30.7C (SD 1.4). While further evaluation ofother relevant properties, such as injectability andin vivobiocompatibility, remains to be done, theresults presented herein are promising in terms of approaching clinically applicable bone cementswith a lower stiffness.
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| 7. |
- Engstrand, Johanna, et al.
(författare)
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Influence of polymer addition on the mechanical properties of a premixed calcium phosphate cement
- 2013
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Ingår i: Biomatter. - : Informa UK Limited. - 2159-2535. ; 3:4, s. e27249-
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Tidskriftsartikel (refereegranskat)abstract
- Premixed calcium phosphate cements can reduce handling complications that are associated with the mixing of cements in the operating room. However, to extend the clinical indication of ceramic cements their mechanical properties need to be further improved. The incorporation of a polymeric material with intrinsically high tensile properties could possibly assist in increasing the mechanical properties of calcium phosphate cement. In this study polymer microparticles made from poly(lactid-co-glycolide) plasticised with poly(ethylene glycol) 400 (PLGA/PEG microparticles) were added in amounts of up to 5 wt% to a premixed acidic calcium phosphate cement. The PLGA/PEG microparticles added undergo a shape transformation at 37°C, which could give a better integration between polymer microparticles and ceramic cement compared to polymer microparticles lacking this property. The results showed that the incorporation of 1.25 wt% PLGA/PEG microparticles increased the compressive strength by approximately 20% up to 15.1 MPa while the diametral tensile strength was kept constant. The incorporation of PLGA/PEG microparticles increased the brushite to monetite ratio after setting compared to pure ceramic cements. In conclusion, small amounts of PLGA/PEG microparticles can be incorporated into premixed acidic calcium phosphate cement and increase their mechanical properties, which could lead to increased future applications.
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| 8. |
- Kootala, Sujit, 1981-, et al.
(författare)
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Co-culture model using human osteoblasts and osteoclasts on bone discs for in situ monitoring of surface remodeling
- 2024
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Ingår i: Biomatter. - : Taylor & Francis Group. - 2159-2535.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Osteoporosis is marked by accelerated bone resorption than bone formation and is currently treated with suboptimal drugs associated with severe off-target effects. More robust in vitro models are needed to investigate the precise pharmacokinetic effects of new drug formulations on bone cells in coculture conditions. This would promote targeted drug development and could reduce the number of animals needed in pre-clinical trials. However, existing coculture models do not address the effect of soluble factors released from cells in coculture. To address this challenge, we developed a two-sided co-culture model comprising human osteoclasts and osteoblasts on opposite sides of a thin decellurized bone chip. Essential cellular functions such as resorption by osteoclasts and mineralization by osteoblasts were not disrupted in the two-sided co-culture, even though the bone chip physically separated the two cell types. In this model, we freshly quantified resorption pits and mineralization on opposite sides of the same material through microscopy assisted image analysis and histological staining, respectively. Mineralization by osteoblasts was assessed with alizarin red and showed downregulation by 25% in the presence of osteoclasts (relative to osteoblasts alone) on the bone chip. The drug Pamidronate reduced the osteoclast population by 10% without affecting the number of osteoblasts. Thus, this co-culture model significantly simplifies allows in-situ monitoring of the effect of soluble bone signaling factors and anti-osteoporotic drugs.
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| 9. |
- Persson, Cecilia, et al.
(författare)
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Premixed calcium silicate cement for endodontic applications : Injectability, setting time and radiopacity
- 2011
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Ingår i: Biomatter. - 2159-2535. ; 1:1, s. 76-80
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Tidskriftsartikel (refereegranskat)abstract
- Calcium silicate based materials (also called MTA) are increasingly being used in endodontic applications. However, the handling properties of MTA are not optimal when it comes to injectability and cohesion. Premixing the cements using glycerol avoids these issues. However, there is a lack of data on the effect of common cement variables on important properties of premixed cements for endodontic applications. In this study, the effects of liquid to powder ratio, amount of radiopacifier and amount of calcium sulphate (added to control the setting time) were screened using a statistical model. In a second part of the study, the liquid to powder ratio was optimized for cements containing three different amounts of radiopacifier. Finally, the effect of using glycerol rather than water was evaluated in terms of radiopacity. The setting time was found to increase with the amount of radiopacifier when the liquid to powder ratio was fixed. This was likely due to the higher density of the radiopacifier in comparison to the calcium silicate, which gave a higher liquid to powder ratio in terms of volume. Using glycerol rather than water to mix the cements led to a decrease in radiopacity of the cement. In conclusion, premixed calcium silicate cements with acceptable properties for use in endodontic applications were produced.
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| 10. |
- Unosson, Erik, et al.
(författare)
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Synergetic inactivation of Staphylococcus epidermidis and Streptococcus mutans in a TiO2/H 2O2/UV system
- 2013
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Ingår i: Biomatter. - : Informa UK Limited. - 2159-2535. ; 3:4, s. e26727-
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Tidskriftsartikel (refereegranskat)abstract
- TiO 2 photocatalysis can be used to kill surface adherent bacteria on biomaterials, and is particularly interesting for use with percutaneous implants and devices. Its efficiency and safety, however, depend on the activation energy required. This in vitro study investigates synergetic effects against the clinically relevant strains S. epidermidis and S. mutans when combining photocatalytic surfaces with H 2O 2. After 20 min exposure to 0.1 wt% H 2O 2 and UV light on TiO 2 surfaces, viabilities of S. epidermidis and S. mutans were reduced by 99.7% and 98.9%, respectively. Without H 2O 2 the corresponding viability reduction was 86% for S. epidermidis and 65% for S. mutans. This study indicates that low concentrations of H 2O 2 can enhance the efficiency of photocatalytic TiO 2 surfaces, which could potentially improve current techniques used for decontamination and debridement of TiO 2 coated biomedical implants and devices.
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