Nickel-containing orthodontic wires have been reported to cause allergic reactions in sensitive individuals. An allergic reaction is related to corrosion of the alloys and subsequent leaching of nickel ions into the oral cavity. The purpose of this study was to determine if there is a significant difference in the corrosive potential of stainless steel, NiTi and TMA wires either alone or when coupled with a stainless steel bracket.;Using potentiostatic anodic polarization, the samples were tested in 0.9% NaCl solution at room temperature with neutral pH. The breakdown potentials of stainless steel, NiTi, TMA, and the stainless steel bracket were 600 mv, 1600 mv, >2000 mv, and 200 mv respectively. When coupled with a stainless steel bracket, the breakdown potential for all three of the wire types was 200 mv. The stainless steel brackets proved to be the weak ling in the galvanic couple with the three wire types and the brackets have a significantly higher corrosive potential than any of the wires themselves.
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