In-situ synchrotron X-ray characterization of corrosion products in Zr artificial pits in simulated physiological solutions

Corrosion products generated in artificial pits of zirconium were characterized in-situ by synchrotron X-ray diffraction and X-ray absorption near edge structure (XANES) in physiological saline, with and without addition of 4% albumin and/or 0.1% H2O2. Zr metal fragments and tetragonal ZrO2 particles were detected in aggregated black corrosion products away from the corrosion front. At the corrosion front, a ZrOCl2·8H2O salt layer of a few hundreds of microns thickness was formed. Coarsened ZrOCl2·8H2O crystallites were found farther out into the solution. The Zr solution species were confirmed to be in a tetravalent state by XANES. TEM imaging of the corrosion products revealed heterogeneity of the morphology of the Zr metal fragments and confirmed their size to be less than a few microns. The formation and speciation of Zr corrosion products were found not affected by the presence of H2O2 and/or albumin in physiological saline. Furthermore, bulk Zr electrochemistry identified that the presence of H2O2 and/or albumin did not affect passive current densities and pitting potentials of the bulk Zr surface. Therefore, it is concluded that the pitting susceptibility and pit chemistry of Zr in physiological saline were unaffected by the presence of H2O2, albumin or their combinations

On the Potential of Bulk Metallic Glasses for Dental Implantology: Case Study on Ti40Zr10Cu36Pd14

Ti40Zr10Cu36Pd14 Bulk Metallic Glass (BMG) appears very attractive for future biomedical applications thanks to its high glass forming ability, the absence of toxic elements such as Ni, Al or Be and its good mechanical properties. For the first time, a complete and exhaustive characterization of a unique batch of this glassy alloy was performed, together with ISO standard mechanical tests on machined implant-abutment assemblies. The results were compared to the benchmark Ti-6Al-4V ELI (Extra-Low-Interstitial) to assess its potential in dental implantology. The thermal stability, corrosion and sterilization resistance, cytocompatibility and mechanical properties were measured on samples with a simple geometry, but also on implant-abutment assemblies’ prototypes. Results show that the glassy alloy exhibits a quite high thermal stability, with a temperature range of 38 °C between the glass transition and crystallization, a compressive strength of 2 GPa, a certain plastic deformation (0.7%), a hardness of 5.5 GPa and a toughness of 56 MPa.√m. Moreover, the alloy shows a relatively lower Young’s modulus (96 GPa) than the Ti-6Al-4V alloy (110–115 GPa), which is beneficial to limit bone stress shielding. The BMG shows a satisfactory cytocompatibility, a high resistance to sterilization and a good corrosion resistance (corrosion potential of −0.07 V/SCE and corrosion current density of 6.0 nA/cm2), which may ensure its use as a biomaterial. Tests on dental implants reveal a load to failure 1.5-times higher than that of Ti-6Al-4V and a comparable fatigue limit. Moreover, implants could be machined and sandblasted by methods usually conducted for titanium implants, without significant degradation of their amorphous nature. All these properties place this metallic glass among a promising class of materials for mechanically-challenging applications such as dental implants

A new, toxic element-free Mg-based metallic glass for biomedical applications

International audienceAs part of a project to develop new and more performant types of metallic glass (MG) for use in biomedical applications, we developed a new ribbon-metallic glass with two different compositions, Mg-(85 (-) Ca-x)((8) (+) Au-x)(7) (with x = 0, 2, 4) and Mg(81 - x)Ca10Au7Yb(2 + x) (with x = 0, 8). The super-cooled liquid region was evaluated to be Delta T = Tx - Tg = 22 degrees C, where Tx is the temperature of crystallization and Tg is the glass transition temperature. The thermal stability of this material was investigated using different measurement methods. No crystallization was detected after 30 min at 120 degrees C, which is of major interest for sterilization processes in the medical field. Resistance to crystallization was also investigated. All the results highlight the suitability of this new metallic glass for biomedical applications

New “ductile” zirconia-based ceramics for the development of dental implants

International audienc

Study of transformation bands in ceria-stabilized zirconia-based composites: Does the transformation-induced plasticity induce damage?

International audienc

A potential renewed use of very heavy ions for therapy: Neon minibeam radiation therapy

(1) Background: Among all types of radiation, very heavy ions, such as Neon (Ne) or Argon (Ar), are the optimum candidates for hypoxic tumor treatments due to their reduced oxygen enhance-ment effect. However, their pioneering clinical use in the 1970s was halted due to severe side effects. The aim of this work was to provide a first proof that the combination of very heavy ions with minibeam radiation therapy leads to a minimization of toxicities, and thus, opening the door for a renewed use of heavy ions for therapy; (2) Methods: Mouse legs were irradiated with either Ne MBRT or Ne broad beams at the same average dose. Skin toxicity was scored for a period of 4 weeks. Histopathology evaluations were carried out at the end of the study; (3) Results: A significant dif-ference in toxicity was observed between the two irradiated groups. While severe damage, in-cluding necrosis, was observed in the broad beam group, only light to mild erythema was present in the MBRT group; (4) Conclusion: Ne MBRT is significantly better tolerated than conventional broad beam irradiations