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

Abstract

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.

Creation of nanostructures to study the topographical dependency of protein adsorption

“…Native silicon Si111 meets this condition having a natural root mean square (RMS)-roughness of 0.2 nm over 10 mm 2 . To study the protein adsorption on Ti surface that is known to be biocompatible [14,15], we also evaporated a 10 nm thick titanium layer on Si at a speed of 50 A , /s. The RMS-roughness of this Ti layer is 0.35 nm for 10 mm 2 surfaces.…”

Microstructures, mechanical behavior, cellular response, and hemocompatibility of bulk ultrafine‐grained pure tantalum

“…Optical microscopy (Olympus BX 51M) was used for microstructural observation of all the pure Ta samples after etching in a mixture solution of two part nitric acid and one part 60% ammonium fluoride in a standard way. The tensile tests (the specimen of 1.5 3 1.5 3 40 mm 3 ) were performed at a strain rate of 0.01 s 21 with an Instron 3366 universal test machine under ambient temperature. Bright field of transmission electron microscopy (TEM; FEI Tecnai G2 T20) and selected area electron diffraction (SAED) were measured, and the dimple samples were prepared by ion milling (Gatan 691) at a slow scan rate in incident gradient angles (from 10 o to 4 o ).…”

Fatigue Property of Ti-5Al-13Ta Alloy Dental Castings in 0.9% NaCl Solution

“…10) They also showed excellent corrosion resistance, 10) comparable castability 11) and wear resistance, 3) therefore, it has been increasingly used in clinical dental treatment. 12,13) Tantalum is another element in the periodic group 5, and it is known to show excellent biocompatibility 14,15) as well as to work as a -stabilizer. 16) In a previous study by the authors, Ti-5Al-13Ta alloy castings showed slightly less strength and much larger elongation than those of Ti-6Al-7Nb alloy castings in tensile test; the mechanical property was between those of CP-Ti and Ti-6Al-7Nb alloy castings.…”