the corrosion of dental orthodontic appliances can have serious clinical implications ranging from loss of dimension to stress corrosion failure of the appliances. The production of possible toxic corrosion products and their absorption by the
surrounding tissue is undesirable.
The study on the toxicity of corrosion products is carried out actively nowadays. And it is the standard practice of biocompatibility test that the elucidation of reaction mechanism between wire and electrolyte using electrochemical corrosion
test.
In this study, five kinds of stainless steel orthodontic wires, four kids of cobalt-chromium othodontic wires and two kinds of nickel-titanium wires were studied using electrochemical method.
@ES The results were follows:
@EN 1. The corrosion potentials of orthodontic wires did not change much after altering the measuring condition, but the zero current potentials of those had great variation after altering the measuring condition.
2. Stainless steel orthodontic wires showed apparent passivation within the oral potential range. In the rescan procedure, the current denstidy was reduced than the first scan and the transformation of oxide layer was observed around -100 mV
(SCE)
in
some wires.
3. Cobalt-chromium orthodontic wires showed passivation starting from -800~-700 mV (SCE), and maintained upto +700 mV/(SCE). In the rescan procedure, the current density was reduced apparently than the first scan and similar potentiodynamic
polarization curve as first scan was obtained after rescan procedure.
4. Nickel-titanium orthodontic wire showed increase of current density in the rage of -100~100 mV(SCE) and showed passivation in the range of +200~+800 mV (SCE). In the rescan procedure, the current density was higher than in the first scan in
some
potential range.
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