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

• Published in: Journal of materials science. Materials in medicine Vol. 22; no. 1; pp. 193 - 200
• Main Authors: Bozzini, Benedetto, Carlino, Paolo, Mele, Claudio
• Format: Journal Article
• Language: English
• Published: Boston Springer US 2011; Springer; Springer Nature B.V
• Subjects: Applied sciences; Biological and medical sciences; Biomaterials; Biomedical Engineering and Bioengineering; Biomedical materials; Body Fluids - chemistry; Body Fluids - metabolism; Body Fluids - physiology; Ceramics; Chemistry and Materials Science; Coated Materials, Biocompatible - chemistry; Composites; Corrosion; Dental Implants; Dental research; Electrochemistry; Exact sciences and technology; Glass; Glycine - chemistry; Glycine - pharmacology; Head and neck surgery. Maxillofacial surgery. Dental surgery. Orthodontics; Humans; Materials Science; Materials Testing; Maxillofacial surgery. Dental surgery. Orthodontics; Medical sciences; Metals. Metallurgy; Microscopy, Electron, Scanning; Models, Biological; Natural Materials; Polymer Sciences; Regenerative Medicine/Tissue Engineering; Solutions - chemistry; Solutions - pharmacology; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; Surface Properties; Surfaces and Interfaces; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Thin Films; Transplants & implants; X-Ray Diffraction; Zirconium - chemistry; Passive Film; Simulate Body Fluid; Solution Simulate Body Fluid; Zirconia Coating; Oxide Film Thickness; Body fluid; Electrochemical properties; Treatment; Corrosion; Surface properties; Zirconium alloy; Dentistry; Glycine; Dental implant; Biomedical engineering
• ISSN: 0957-4530; 1573-4838
• DOI: 10.1007/s10856-010-4187-1

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.