Electrochemical in vitro Properties of 316L Stainless Steel for Orthodontic Applications

Abstract

316L Stainless steels are widely used in biomedical applications with respect to their excellent corrosion resistance, nonmagnetic properties, high ductility and acceptable biocompatibility. There have been made electrochemical studies in-vitro in order to determine the corrosion reactions, which are necessary for foreseeing the behavior of the materials used in orthodontic applications. The degradation of metals and alloys in the human body is a combination of effects due to corrosion and mechanical activities. In dentistry, 316L stainless steel are used in a variety of applications: sterilized instruments, endodontic files in root canal therapy, metal posts in root canal treated teeth, temporary crowns, arch wires and brackets in orthodontics, a necessary condition for these applications must to resist to pitting corrosion. The pitting corrosion can be observed only in the case of passivable steels and in the presence of halogen or sulphur ions, in saline or acidic media like the human body. this type of corrosion propagates under the form of small pits, which give off to a significant quantity of metal ions, being very dangerous to the body. The metal ions resulted from the corrosive processes have allergic, carcinogenic and cytotoxic effects. The aim of this work was to evaluate the corrosion behavior of 316L stainless steel immersed in two artificial saliva solutions. The electrochemical measurements such as: open Circuit Potential (OCP), linear Polarization Resistance (LRP), and electrochemical Impedance Spectroscopy (EIS), methods were used to fulfill the corrosion evaluation. The research work concludes that the increase of the pH with a higher concentration of chloride contents lead to a lowest corrosion resistance while a decrease of the pH with a lowest concentration of chlorides contents reveals a higher corrosion resistance.