Electrochemical behaviour and surface characterisation of Zr exposed to an SBF solution containing glycine, in view of dental implant applications

Abstract

Zr and Ti alloys are extensively used in the biomedical field owing to their optimal mechanical properties and excellent corrosion resistance. Fully ceramic implants based on zirconia are appealing with respect to the traditional Ti-based metallic ones for several reasons, such as: (i) improved aesthetic impact, (ii) better biocompatibility and (iii) better osteointegration. Nevertheless, fully ceramic implants exhibit serious mechanical and clinical drawbacks, chiefly brittleness and impossibility of post-implant position adjustments. In this paper we propose the novel approach of using a metal-based system, consisting of metallic Zr, for the bulk of the implant and an electrochemically grown zirconia coating, ensuring contact of the ceramic with the biological environment and isolation from the underlying metal. This solution combines the outstanding mechanical properties of the metal in the bulk with the optimal biochemical properties exclusively where they are needed: at the surface. The present paper-focussed on the electrochemical behaviour of the proposed system at the implant-wound and implant-growing bone interface-reports a time-dependent electrochemical corrosion study of zirconia-coated zirconium, performed in the following ways: (i) exposure and measurements in SBF (simulating the inorganic part of human plasma, relevant to wound chemistry), (ii) exposure and measurements in SBF with added glycine (the simplest, ubiquitous amino acid found in proteins), (iii) exposure in SBF with added glycine and measurements in SBF. Electrochemical impedance spectra were measured and interpreted with the equivalent-circuit approach, yielding estimates of the time-variation of the oxide film thickness and resistance were estimated. FT-IR, Surface Raman and VIS reflectance spectroscopies were used to characterise the surface before and after the exposure to SBF solutions. Spectroelectrochemical measurements revealed an higher corrosion resistance of the oxide films formed on Zr in the presence of glycine in the SBF matrix and a smoother electrode surface.

Electrochemical synthesis of oxide nanotubes on Ti6Al7Nb alloy and their interaction with the simulated body fluid

“…It incorporates two time constants which can be deducted from Bode plots. In both the cases, there is a decrease of α O which means deviation from pure capacitance due to surface inhomogenity [35]. It may be a result of apatite deposition on the surface of nanotubes.…”

“…9a-d. For the interpretation of the experimental data, we used equivalent circuits available in the literature [12,[35][36][37], which have been often applied to dense and porous oxide layer formed on the metal surface immersed in the electrolyte. Both models are based on Randles circuit and are shown in Fig.…”

“…For α = 1, Z CPE corresponds to the capacitor, for α = 0, it takes part of the resistor, and for α = −1, it corresponds to the inductor [36,38,39]. In all the cases, the simplest equivalent circuits were chosen in order to achieve lower confidence intervals for the estimated parameters and to capture all qualitative features of the impedance spectra [35].…”

Microstructure, mechanical property, corrosion behavior, and in vitro biocompatibility of Zr–Mo alloys

“…14,15 It was suggested that their corrosion resistance would be further improved by alloying 16,17 or surface treatment. 18,19 The oxinium (surface oxidized Zr-2.5Nb alloy) has been commercially used as knee and hip femoral heads in total joint arthroplasty owing to its superior wear resistance. 20,21 Moreover, the surface oxidized zirconium alloy exhibited an excellent anti-bacterial property.…”

In-Situ Synchrotron X-ray Characterization of Corrosion Products in Zr Artificial Pits in Simulated Physiological Solutions

“…Both species were demonstrated to adsorb onto the metal surface but contradictory effects (suppressing or accelerating) were claimed on the corrosion of Zr. 26,27 It has also been reported that the presence of H 2 O 2 reduces the corrosion resistance of thermally oxidized Zr5Ti where surface oxides are mostly composed of ZrO 2 . 29 No studies have been reported on the combined effect of H 2 O 2 and albumin in terms of corrosion and corrosion products.…”