Date of Award
Summer 7-9-2025
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
David Berzins
Second Advisor
Dawei Liu
Third Advisor
Spencer Pope
Abstract
Objective: Esthetics are becoming more important to patients with increased desire for ceramic brackets as they go through orthodontic treatment. Despite ceramic brackets offering an esthetic option for patients, traditional metal wires are still most commonly being used. Very little research on rhodium plated wires, specifically the American Orthodontics Iconix Aesthetic Arch Wire, exists in the literature with no tests of corrosion through electrochemical testing. The objective of this research is to analyze how rhodium plating affects the electrochemical properties of nickel-titanium (NiTi) orthodontic wires. Methods: Rhodium-plated NiTi orthodontic wires (Iconix Aesthetic; American Orthodontics) and non-plated NiTi orthodontic wires (NT3 SE NiTi Wire; American Orthodontics) were compared. Ten wires of each were prepared by isolating 50 mm of wire using nail polish and exposing it to Fusayama-Meyer artificial saliva solution. A potentiostat was used for testing with the wire serving as the working electrode, saturated calomel as the reference electrode, and graphite as the counter electrode. The following 3 tests were performed: the open circuit potential (OCP) was monitored for 2 hours followed by a polarization resistance test and cyclic polarization. OCP at 2 hours, polarization resistance (Rp), corrosion current (Icorr), and presence of pitting were determined. Results: OCP results at 2 hours favored the Iconix wire at 360±2 mV (vs SCE) compared to -40±44 mV (vs SCE) of NiTi, indicating that the Iconix wire is more noble/cathodic in nature with less tendency for corrosion. The polarization resistance (Rp) showed no statistically significant difference between the two wires. Cyclic polarization results show that the Iconix wire had a significantly greater corrosion current (Icorr) than NiTi wire, even though some of the NiTi wires exhibited pitting corrosion. Conclusion: Despite showing less tendency for corrosion in an open circuit, the Iconix wire exhibited greater corrosion current implying a greater ion release. Rhodium plating may still be beneficial, as the ions released are likely from the coating rather than from nickel in the base wire. Further testing is recommended to evaluate the specificity of the ions released.