In Vitro Corrosion Resistance of Orthodontic Super Stainless Steel Wire

Abstract

Generally, orthodontic stainless steel wires are made with 18-8 stainless steel, but because of the low localized corrosion resistance of this steel, the probability of corrosion is high. The desired properties for wires to be used in the oral cavity include high corrosion resistance and optimal mechanical properties. The metallurgical properties, corrosion resistance, and ion release properties of rectangular wire produced experimentally with super stainless steel (S32050) by a drawing process were evaluated, these properties compared with Remanium, Permachrome, G&Hwire, and Orthos, and the consequent capability of this steel to satisfy the optimal property levels required for orthodontic wire are discussed. Except for S32050, the wires formed twinned martensite in severely deformed grains. S32050 exhibited a low current density of about 1.6 μA/cm2 and a stable passive region in artificial saliva, but the comparative wires displayed high current density because of pitting that occurred above the breakdown potential. S32050 released only a small amount of nickel into the solution in spite of its high nickel content. The high corrosion resistance of S32050 wire inhibits the release of metallic ions in the oral cavity and therefore satisfies the requirements of orthodontic wire. © 2002 The Electrochemical Society. All rights reserved.

Stainless Steel: Material Facts for the Orthodontic Practitioner

“…Therefore, a super austenitic stainless steel, known as sr-50a, has been reported as having localized corrosion resistance similar to that of titanium alloys because the passive film is enhanced by the synergistic effect of high concentrations of nitrogen (0.331%) and molybdenum (6.77%) [21,30]. This alloy has been used experimentally for manufacturing orthodontic brackets and wires with very promising results [21,30,31]. …”