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Two approaches can be taken when designing properties of the native oxide layers formed on Ti-based biomedical materials: (i) changing the chemical composition of the substrate by adding biocompatible, valve alloying elements, and (ii) changing the microstructure of the substrate—especially its level of defectiveness—through large plastic deformation. However, especially in the aggressive fluoridated oral environment, it is still unknown what factor is more effective in terms of enhancing oxide layer protectiveness against biocorrosion: (i) the presence of valve alloying elements, or (ii) a high number of structural defects. To gain knowledge about the separate influence of both of these factors, surface properties were examined for commercially pure Ti and Ti–Nb–Ta–Zr alloy in microcrystalline state as well as after multiple-pass cold rolling, a process that can be readily scaled up to the industrial level. This study showed that while valve-alloying elements and structural defects individually have a beneficial effect on Ti oxide layer properties in fluoridated medium, they not have to act in a synergistic manner. These findings have to be taken into account when designing future Ti-based dental materials together with analyzing their mechanical performance with respect to mechanical strength and elastic properties.

This study concerns a detailed cross-section microstructural analysis conducted by combining complementary methods such as FIB, SEM, EDS and STEM on different scales in order to elucidate the impact of direct laser interference lithography on the microstructure and surface chemistry of a Ti substrate after laser patterning. Special attention was paid to correlate the mechanical properties determined by the nanoindentation tests with the microstructure and phase composition analysed using GI-XRD. Direct laser interference lithography surface texturing results in the formation of a thin (1–1.5 μm), continuous layer with lath-like grains. The GI-XRD analysis showed no changes in phase composition, which is in agreement with our previous results. Furthermore, laser patterning led to an increase in the nano-hardness of the surface (from 2.8 GPa to 6.6 GPa) that is mainly related to the changes that took place in the microstructure. The results presented are important to an evaluation of laser-patterned surfaces in biomedical applications, as their ultimate use depends not only on topographical changes but also mechanical properties variations as well as microstructure evolution which affects its electrochemical properties.

Nanocrystalline titanium, mainly owing to its high corrosion resistance, mechanical strength to density ratio and biocompatibility, has a great application potential in dental implantology. However, fluoridated agents commonly used for oral hygiene could have a destructive influence on the titanium protective passive films and lead to the formation of local corrosion damages. In this work, the effect of nanostructuring on titanium corrosion resistance in the concentration of F− which is typical for toothpastes, was evaluated by different electrochemical and surface characterisation techniques. It was found that nanostructure influences beneficially on titanium corrosion resistance in fluoride solution. Furthermore, the lower increase in nanocrystalline titanium surface roughness in corrosion solutions indicates better stability of passive film formed on its surface.

This paper reports on the corrosion behavior of Titanium Grade 2 when subjected to non-contact laser functionalization. Direct Laser Interference Lithography (DLIL) was used to create periodic topography with two different surface patterns on pre-modified titanium. Corrosion resistance was measured in physiological saline at 37 °C. Electrochemical Impedance Spectroscopy data (EIS) and potentiodynamic polarization curves were correlated with the characteristics of the passive films through analysis of the topography, chemical composition, and thickness of oxides formed on the titanium after surface modifications. The corrosion tests showed that laser-textured surfaces have a beneficial impact on titanium corrosion resistance in a physiological saline solution 0.9% NaCl. Moreover, the passive layer on DLIL-modified samples is more stable and less susceptible to growth in the corrosive environment. The results highlight the local interaction of DLIL treatment of the titanium surface after it had been shot-peened and acid-etched. The improved corrosion resistance in DLIL samples derives mainly from changes in the surface topography, chemical composition, and thickness of oxide films obtained after laser processing.

The main aim of this study was to investigate the effect of plastic deformation on the biological behaviour of novel Ti-29Nb-13Ta-4.6Zr alloy and to compare it with microcrystalline α titanium, commonly used in medicine. A multiple-stage cold rolling process was applied to improve both the mechanical and functional properties in a TNTZ alloy. A systematic characterization of the microstructure of all tested materials was performed, followed by a correlation with the mechanical properties and phase composition. A cellular response test based on osteosarcoma MG63 osteoblast like cells was carried out in order to analyse the influence of plastic deformation on the biocompatibility of the TNTZ alloy subjected to cold rolling. A detailed surface characterization including inter alia: contact angle and surface free energy, XPS, AES and AFM, was made to define the key factors affecting cellular adhesion to the surface of the deformed samples. The adhered cells were analyzed using confocal and atom force microscopies after 4 days of incubation. Our initial tests indicated that the novel β-Ti alloy subjected to the cold rolling process could be a promising new candidate in the fields of orthopaedics and dentistry implantations.

Hydrogen peroxide (H2O2), which is produced during inflammation directly after the insertion of an implant, accelerates the corrosion process of Ti-based materials such as nanocrystalline bulk titanium. For this reason, there is a need to provide additional corrosion protection in the initial period following implantation. Coatings based on chitosan/bioactive glass were obtained by electrophoretic deposition (EPD) on nanocrystalline Ti. Results indicated that homogeneous, crack-free composite chitosan/bioactive glass EPD coatings effectively increased the resistance of nanocrystalline titanium to dissolution induced by H2O2.

Severe Plastic Deformation (SDP) processes including Hydroextrusion (HE) causes the change of the mechanical properties by the introduction of a large number of defects and significant refinement of the microstructure. During the initially stages of HE microstructure becomes more elongated according to the extrusion direction. Only after a certain deformation, grains become more equiaxed. Present studies are intended to determine the influence of the titanium Grade2 microstructure and grain size distribution on its corrosion properties. All corrosion tests were conducted in a 0.9 % NaCl solution at room temperature. Electrochemical Impedance Spectroscopy (EIS) was measured after 2 and 24 hours. Also Potentiodynamic Polarization was conducted after 24 hours. Microstructures were reviled using Scanning Electron Microscopy and Transmission Electron Microscopy. Grain size distribution was determined using the program Micrometer . The results confirmed formation of titanium dioxide and very good corrosion properties of titanium Grade2 at all stages of hydrostatic extrusion.