Galvanic Corrosion Between Ti/Ti6Al4V and Various Dental Alloys

Daniel Mareci,Neculai Aelenei,Gheorghe Nemtoi,Catalin Bocanu

doi:10.18321/ectj615

Daniel Mareci, Neculai Aelenei + Show 2 more

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https://doi.org/10.18321/ectj615

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Abstract

The corrosion tendencies of metals are related with their position in the electromotive series. These electrode potential degrees may change due to the composition of the alloys, the surrounding medium or due to the alterations in the composition because of the recurrent costing. The galvanic corrosion appears when different electrochemical potentials are bound to one another and the electrical conductibility is assured by the presence of an electrolyte. It is difficult to avoid coupling of different metals, a problem concerning the choice of the alloy used for the implant bone supra-structure. One has studied the galvanism of several couples formed between a dental implant and diverse dental alloys in Afnor saliva. The electrochemical behavior of 8 commercial dental alloy superstructures with titanium and titanium alloy (Ti6Al4V) implants was investigated by electrochemical techniques. Non-precious alloys were Ni-Cr based (Wiron NT and Verasoft), Co-Cr based (Vitallium alloy) and Cu based (Gaudent). Semi-precious alloys were Ag-Pd based (RX91 and Unique White). The precious alloys were Au-Pd based (Ceram) and Au-Ag based (Argenco). Some of the corroded and non-corroded surfaces were observed by optical microscopy. From linear polarization curves the corrosion potential and the current densities were evaluated. The results showed very low corrosion rates, ranking from 10-6 to 10-9 A/cm2. All the results obtained indicate the fact that the corrosion process intensity corresponding to the coupling between titanium (respectively Ti6Al4V) and semi-precious alloys is reduced. The surface of precious and semi-precious alloys is not attacked, but the titanium (Ti6Al4V) surface is oxidized in time.

Highlights

Titanium and titanium alloys are used as biomaterials is due to advantages presented in comparison with other similar materials: chemical inertia [1], low densities [2], toxicity absence [3] and increased biocompatibility [4]
Galvanic corrosion may appear when metals having different electrochemical potentials are electrically connected and the electrical conductibility is assured by the presence of an electrolyte
In an earlier paper the galvanic corrosion between Ti6Al4V alloys and some noble and semi-noble dental alloys was studied in two artificial saliva types by electrochemical techniques and auger spectrometry [5]

Summary

Introduction

Titanium and titanium alloys are used as biomaterials is due to advantages presented in comparison with other similar materials: chemical inertia [1], low densities [2], toxicity absence [3] and increased biocompatibility [4]. The passive state of titanium and it's alloys is determined by a film with reduced thickness, formed on metal surface and very adherent to it. This film functions as a barrier blocking the metal tendency to interact with the corrosion medium. Galvanic corrosion may appear when metals having different electrochemical potentials are electrically connected and the electrical conductibility is assured by the presence of an electrolyte. This type of corrosion occurs due to differences that exist between corrosion potentials of the two metals immersed in the same corrosion environment. In an earlier paper the galvanic corrosion between Ti6Al4V alloys and some noble and semi-noble dental alloys was studied in two artificial saliva types by electrochemical techniques and auger spectrometry [5]

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