Engineers searching new dental biomaterials try to modify the structure of the material in order to achieve the best performance as well as increased migration and proliferation of cells involved in the osseointegration of the implant. In this work we show in vitro test results of the Ti, which was anodically oxidized at high voltages with additionally deposited silver in the form of nanodendrites. The in vitro cytocompatibility of these materials was evaluated and compared with a conventional microcrystalline titanium. During the studies, established cell line of human gingival fibroblasts (HGF) and osteoblasts were cultured in the presence of tested materials, and its survival rate and proliferation activity were examined. Titanium samples modified with silver has a higher degree of biocompatibility in comparison with the unmodified reference material. Cells in contact with studied material showed a higher relative viability potential, stable level of proliferation activity, and lower rate of mortality. Biocompatibility tests carried out indicate that the anodically oxidized titanium at high voltages with additionally deposited nanosilver could be a possible candidate for dental implants and other medicinal applications.
The nanocrystalline refractory tantalum alloys were made using mechanical alloying. The tantalum alloys were modified by niobium, molybdenum and tungsten in the concentration of 5, 10, 20 and 40 wt.%. The nanocrystalline powders were consolidated (hot-pressed) using the pulse plasma sintering mode. The hot pressing at the temperature of 1300 o C results in an increase of the grain size, in comparison to mechanically alloyed powders. However, the lowest grain size (significantly below 100 nm) was achieved for Ta-W alloys (approximately 40-60nm). The grain size was confirmed by XRD, TEM and AFM. The most uniform microstructure is also exhibited by the Ta-W alloys. The corrosion resistance was measured using the potentiodynamic mode in a chloride solution. The nanocrystalline Ta-Mo and Ta-W alloys achieved the same level of corrosion resistance as microcrystalline pure tantalum and 3 orders of magnitude better than pure nanocrystalline tantalum. Among all the prepared nanocrystalline tantalum alloys, the most promising properties exhibit those having 10% of the tungsten addition.
The publication presents the influence of an external magnetic field of 1.2T on the process of silver deposition. The external magnetic field interacted perpendicularly to the sample surface during the deposition process. The surface of the titanium sample was pre-modified by anodic oxidation. Such a surface modification causes the deposited silver to take the form of dendrites. As a result of the influence of the magnetic field, the silver dendrites were shortened and the size of their crystallites was reduced. Changes have also been reported at the nucleation stage during the deposition process. The negative magnetic field accelerated the process, causing the deposited silver particles to become thinner. The positive magnetic field slowed down the process, causing the deposited silver particles to become thicker. By modifying the magnetic field, the morphology of the deposited silver particles can be changed.
The paper presents results of preparation and modification of Ti20Nb5Zr foams by a thermal dealloying method followed by electrochemical modification. The first step of this study was the preparation of Ti20Nb5Zr30Mg nanopowder using mechanical alloying (MA). The second was forming green compacts by cold pressing and then sintering with magnesium dealloyed from the structure, which resulted in pores formation. The next step was surface modification by electrochemical etching and silver nanoparticle deposition. Porosity, morphology, mechanical properties as well as biocompatibility and antibacterial behavior were investigated. Titanium foam porosity up to approximately 60% and wide pore size distribution were successfully prepared. The new materials have shown positive behavior in the MTT assay as well as antibacterial properties. These results confirmed great potential for thermal dealloying in preparation of porous structures.
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