Session Overview |
Friday, May 24 |
08:30 |
The digital twin for degradable Mg-implants
* Regine Willumeit-Roemer, Helmholtz Center Hereon, Germany Berit Zeller-Plumhoff, Helmholtz Center Hereon Christian Cyron, Helmholtz Center Hereon Magnesium as degradable implant material shows great potential. Especially if the degradation rate is tailored to the needs of the surrounding tissue. This means that we should correlate microstructural properties with ion release and tissue regeneration. While on the material side a variety of computational models are available, cell culture data which deliver an ion concentration range suitable for tissue regeneration also working in animals is not sufficient. Simulation and modelling might help in two ways: beside the direct prediction of e.g. osteogenic activity, we can also identify “missing links” if the computational data does not fit the experiment. |
09:15 |
Biodegradation Behavior and Biocompatibility of Zn-Fe-Mg alloy Produced by Powder Metallurgy for Guided Bone Regeneration Application
* Kun Yu, Central South University, China (People's Republic of) Guided bone regeneration (GBR) is currently an effective method to treat the lack of bone mass which will influence the application of implant restorations. Zinc and its alloys can be selected as a good candidate for using as GBR membrane due to its biodegradation and biocompatibility. In this study, two experimental Zn-Fe-Mg alloy foils prepared by powder metallurgy and rolling method were evaluated their mechanical properties, biodegrade behavior and biocompatibility as GBR membranes. The Zinc, Magnesium and Iron powders were blended with the compositions of Zn-0.5%Fe-0.05%Mg and Zn-0.5%Mg-0.05%Fe and sintered at 400 with the pressure of 40Mpa. The sintered experimental ingots were hot rolled at 250 and then cold rolled at ambient temperature to 0.1mm. The tensile strengths of the Zn-0.5Fe-0.05Mg and Zn-0.5Mg-0.05Fe alloy GBR membranes were 145 and 154 MPa, respectively. And the elongations were 42.8 and 41.2%, respectively. It shows that the addition of Fe and Mg can greatly increase the strength of zinc alloy. The corrosion potentials of Zn-0.5Fe-0.05Mg and Zn-0.5Mg-0.05Fe alloy GBR membranes were -1.296 V and -1.309 V, respectively, with corrosion current densities of 12.05μA/cm2 and 13.65μA/cm2 and corrosion rates of 0.180 mm/year and 0.210 mm/year. And the corrosion rates of Zn-Fe-Mg alloys increase to about 0.2mm/year and show obvious biodegradation characteristic in simulated body solution. The Zn-Fe-Mg foils obtain no cytotoxicity and good osteogenic possibility with the in vitro and in vivo test. Especially in the cranial parietal bone defect experiment of rabbits, the Zn-0.5Mg-0.05Fe alloy show a high compatibility to promote bone growth with a quantitative bone volume ratio of 65.5%. And the inducing osteogenesis mechanism of Zn-Mg-Fe alloy is analyzed with genetic expression. All these results suggest that the powder metallurgy is an effective method to produce Zn-Fe-Mg foil which can be used as a promising biodegradable GBR membrane. |
09:30 |
Reduced bone resorption in the area of magnesium cylinders within the subchondral bone of osteoarthritic rabbits
* Nina Angrisani, Hannover Medical School, Clinic of Orthopedic Surgery, Germany Heike Helmholz, Helmholtz-Center Hereon, Institut of Metallic Biomaterials, Germany Henning Windhagen, Hannover Medical School, Clinic of Orthopedic Surgery Björn Wiese, Helmholtz-Center Hereon, Institut of Metallic Biomaterials Regine Willumeit-Roemer, Helmholz-Center Hereon, Institute of Metallic Biomaterials Janin Reifenrath, Hannover Medical School, Clinic of Orthopedic Surgery Osteoarthritis (OA) has one of the highest prevalences in joint diseases around the world. Beside cartilage degeneration and osteophyte formation, subchondral bone sclerosis is one of its predominant features, which affects the biomechanical properties of the subchondral tissue network. Increased transmission of loads to the cartilage may contribute to further progression of the disease. Therefore, influencing bony properties might propose a possible way of treatment. Magnesium (Mg) and Mg alloys are well-known to be osteoconductive. It was already shown by µ-computed tomographical examinations that implantation of small Mg cylinders led to significantly increased bone volume in the subchondral area after an implantation time of eight weeks in osteoarthritic rabbits. However, there was no influence on the histological state of cartilage. Since the exact mechanisms of OA progression still have to be ruled out, there is need for further inside into the cellular components of osteoarthritic tissue. A total of 36 female New Zealand White rabbits were included in this study. After transection of the anterior crucial ligament and incision into the medial meniscus, animals developed OA during a 12 weeks period. Then, animals were divided into three groups, which received either sole drilling holes, drilling holes filled with Mg cylinders or drilling holes filled with WE43 cylinders. Follow-up was eight weeks. After euthanasia, femur condyles were separated and embedded in Technovit 9100. 4µm thin sections were stained for osteoclasts using TRAP and counterstained with haemalum. Tibial bones were processed for ELISA tests using Cartilage Oligomeric Matrix Protein (COMP) as marker for cartilage degeneration associated with OA. Mg and Mg alloys lead to a reduced number of bone resorbing cells compared to sole drilling. Thus, the histologic evaluation of osteoclasts confirmed the previously reported μ-computertomographic results of increased bone volume on the cellular level. Also, the missing impact on cartilage degeneration by OARSI scoring was confirmed in marker-based evaluation using ELISA for COMP. |
09:45 |
Effect of Zr content on structural, mechanical and biodegradability properties of Zn-Mg-based thin films deposited by magnetron sputtering
* Fatiha Challali, Laboratoire des Sciences des Procédés et des Matériaux, Université Sorbonne Paris Nord, France Cristiano Poltronieri, Laboratoire des Sciences des Procédés et des Matériaux, Université Sorbonne Paris Nord Velérie Bockelée, Laboratoire des Sciences des Procédés et des Matériaux, Université Sorbonne Paris Nord Marie-Paule Besland, Nantes Université, CNRS, Institut des Matériaux de Nantes Jean Rouxel, Frederic Chaubet, Laboratory for Vascular Translational Science, Inserm U1148, Université Sorbonne Paris Nord Philippe Djemia, Laboratoire des Sciences des Procédés et des Matériaux, Université Sorbonne Paris Nord This work aims to improve the glass forming ability (GFA) and corrosion resistance of Zn and/or Mg based thin films with Zr added by magnetron co-sputtering. We succeed to correlate their structure with their mechanical properties and corrosion behavior. |