The electrochemical behavior of metallic implant materials as an indicator of their biocompatibility

This study introduces a simple in vitro arrangement to measure current densities of implant metals. The in vivo condition of a metallic implant lying in tissues exhibiting different redox potentials is simulated in so‐called straddle tests by applying a constant potential difference of 250 mV in sal...

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Bibliographic Details
Published in:Journal of biomedical materials research 1987-07, Vol.21 (7), p.881-896
Main Authors: Zitter, H., Plenk Jr, H.
Format: Article
Language:English
Subjects:
Biocompatible Materials
Biological and medical sciences
Electric Conductivity
Electrochemistry
Electrolytes
Ferricyanides
Medical sciences
Metals
Niobium
Orthopedic surgery
Oxidation-Reduction
Prostheses and Implants
Solutions
Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases
Tantalum
Titanium
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Summary:This study introduces a simple in vitro arrangement to measure current densities of implant metals. The in vivo condition of a metallic implant lying in tissues exhibiting different redox potentials is simulated in so‐called straddle tests by applying a constant potential difference of 250 mV in saline containing the stable, fast‐reacting redox system K4Fe(CN)6/K3Fe(CN)6. From a variety of corrosion‐resistant implant metals and alloys, gold showed the highest current densities, followed by the stainless steel, the cobalt‐based alloy, and the TiAIV‐alloy. The pure metals titanium, niobium, and tantalum showed the lowest values. This can be explained by the stable oxide layer on these base metals, preventing an exchange of electrons and thus any redox reaction. This rating of metallic implant materials based on in vitro measurements of current densities is in good accordance with their biocompatibility rating reported from in vivo experiences. It seems that simple and cheap electrochemical tests allow an even more precise differentiation of the suitability of metallic materials for implant purposes than most of the conventional implantation tests, considering that biocompatibility is not only determined by corrosion products, but also by exchange currents and reaction products of redox processes involving tissue compounds.
ISSN:0021-9304
1097-4636
DOI:10.1002/jbm.820210705