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Bereich: Suchergebnisse
Publikation Novel microcalorimetric assay for antibacterial activity of implant coatings. The cases of silver‐doped hydroxyapatite and calcium hydroxide(Wiley, 08/2015) Braissant, Olivier; Chavanne, Philippe; de Wild, Michael; Pieles, Uwe; Stevanovic, Sabrina; Schumacher, Ralf; Straumann, Lukas; Wirz, Dieter; Gruner, Philipp; Bachmann, Alexander; Bonkat, GernotBiomaterials with antimicrobial properties are now commonly used in different clinical specialties including orthopedics, endodontic, and traumatology. As a result, assessing the antimicrobial effect of coatings applied on implants is of critical importance. In this study, we demonstrate that isothermal microcalorimetry (IMC) can be used for monitoring bacterial growth and biofilm formation at the surface of such coatings and for determining their antimicrobial effects. The antibacterial effects of silver doped hydroxyapatite (HA) and calcium hydroxide coatings on Staphylococcus epidermidis were determined with a minimal workload. Using the Gompertz growth model we determined biofilm growth rates close to those values reported in the literature. Furthermore, we were able to estimate the reduction in the bacterial inocula originally applied at the surface of the coatings. Therefore, in addition to monitoring the antimicrobial effect of silver doped HA and calcium hydroxide coatings, we also demonstrate that IMC might be a valuable tool for assessing such antimicrobial properties of implant coatings at a minimal workload.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Tailoring selective laser melting process parameters for NiTi implants(Springer, 12/2012) Bormann, Therese; Schumacher, Ralf; Müller, Bert; Mertmann, Matthias; de Wild, MichaelComplex-shaped NiTi constructions become more and more essential for biomedical applications especially for dental or cranio-maxillofacial implants. The additive manufacturing method of selective laser melting allows realizing complex-shaped elements with predefined porosity and three-dimensional micro-architecture directly out of the design data. We demonstrate that the intentional modification of the applied energy during the SLM-process allows tailoring the transformation temperatures of NiTi entities within the entire construction. Differential scanning calorimetry, x-ray diffraction, and metallographic analysis were employed for the thermal and structural characterizations. In particular, the phase transformation temperatures, the related crystallographic phases, and the formed microstructures of SLM constructions were determined for a series of SLM-processing parameters. The SLM-NiTi exhibits pseudoelastic behavior. In this manner, the properties of NiTi implants can be tailored to build smart implants with pre-defined microarchitecture and advanced performance.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Pre-process calculation to optimize laser parameter in selective laser melting(2018) Matter, Nathalie; Schuler, Felix; Schumacher, Ralf; de Wild, Michael04B - Beitrag KonferenzschriftPublikation Reduction of particles on SLM surfaces(2018) Zimmermann, Simon; Schumacher, Ralf; Bill, Oliver; Dalcanale, Federico; de Wild, Michael04B - Beitrag KonferenzschriftPublikation Mechanical anisotropy of titanium scaffolds(De Gruyter, 2017) Weber, Franz E.; de Wild, Michael; Rüegg, Jasmine; Schumacher, RalfThe clinical performance of an implant, e.g. for the treatment of large bone defects, depends on the implant material, anchorage, surface topography and chemistry, but also on the mechanical properties, like the stiffness. The latter can be adapted by the porosity. Whereas foams show isotropic mechanical properties, digitally modelled scaffolds can be designed with anisotropic behaviour. In this study, we designed and produced 3D scaffolds based on an orthogonal architecture and studied its angle-dependent stiffness. The aim was to produce scaffolds with different orientations of the microarchitecture by selective laser melting and compare the angle-specific mechanical behaviour with an in-silico simulation. The anisotropic characteristics of open-porous implants and technical limitations of the production process were studied.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Patient-specific hip prostheses designed by surgeons(De Gruyter, 30.09.2016) Coigny, Florian; Todor, Adrian; Rotaru, Horatiu; Schumacher, Ralf; Schkommodau, ErikPatient-specific bone and joint replacement implants lead to better functional and aesthetic results than conventional methods [1], [2], [3]. But extracting 3D shape information from CT Data and designing individual implants is demanding and requires multiple surgeon-to-engineer interactions. For manufacturing purposes, Additive Manufacturing offers various advantages, especially for low volume manufacturing parts, such as patient specific implants. To ease these new approaches and to avoid surgeon-to-engineer interactions a new design software approach is needed which offers highly automated and user friendly planning steps.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation 3D Printing in Medicine: Revolution or Illusion?(2016) Schumacher, Ralf06 - PräsentationPublikation 3D Printing in Medicine: Revolution or Illusion?(2016) Schumacher, Ralf06 - Präsentation
