Some ideas about electrochemical characterization of dental alloys

Abstract

Extensions and modifications of standard electrochemical techniques, accounting for unique
 conditions related to biological considerations, have proved useful in attacking some problems
 related to biocompatibility of the Biomaterial. Some authors have demonstrated that modern
 electrochemical techniques can be used to clarify some difficult problems in the field of biomaterials.
 Precious alloys can not be apply for all cases especially such as long range bridges or prostheses.
 For this reason, Ni-Cr as well as Co-Cr casting alloys have been used for dental application as
 alternatives to precious alloys. The biocompatibility of Ni-Cr alloys have been questioned because
 of their corrosive, allergenic, and even mutagenic potentials.
 The nature of passive films on metals and alloys is the ultimate factor which controls their
 corrosion behavior. There is little reliable information on the effects of the physical and chemical
 factors involved in the tissue response to an implant and the associated ionic release on the cellmaterial
 interaction.
 Depending of the casting process during the production of a dental prosthesis, these alloys may
 show different phases, ones may be more stable than other. For this reason, the development of a
 quick and simple method for determining the corrosion behavior as a control test in the production
 Biomecánica, 9 (1), 2001, pp. 66-70
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 of a dental prosthesis is of great interest.
 The purpose of this work was to show some results on the corrosion behavior of two different
 commercial alloys: Wiron 99 ( Ni-Cr alloy) and Aurolloyd kf (Au alloy). These results were obtained
 by several electrochemical methods: Open Circuit Potential vs time and Liner Sweep Voltammetry
 for Wiron 99, and Open Circuit Potential vs time and Cyclic Voltammetry for Aurolloyd kf. In the
 case of the Ni-Cr alloys, it is concluded that with the combination of both methods, it is possible to
 know how the corrosion behavior of casting individual dental Ni-Cr alloy prosthesis is, and in the
 case of Au alloy, it is concluded that the differences in electrochemical behavior strongly depend of
 surface oxides formed. These results showed that one of the studied combination, Eoc-Rp or Eoc-CV
 characterization, could be selected as control test after casting of individual prosthesis.