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Microanalytical characterization and surface modification of TiNi orthodontic archwires
Y Oshida1, R C Sachdeva, S Miyazaki
1Department of Dental Materials, Indiana University, School of Dentistry, IUPUI, Indianapolis 46202-5186.
Bio-Medical Materials and Engineering
|January 1, 1992
Summary
Surface analysis of titanium-nickel (TiNi) orthodontic archwires revealed contaminants on used wires and irregular structures on both used and unused wires. Electrochemical treatment can create a porous, titanium-rich surface, potentially reducing friction.
Area of Science:
- Materials Science
- Biomaterials Engineering
- Corrosion Science
Background:
- Orthodontic archwires made of equiatomic titanium-nickel (TiNi) alloy are crucial in dental treatments.
- Understanding the surface characteristics and corrosion behavior of TiNi archwires is essential for clinical performance and patient safety.
Purpose of the Study:
- To characterize the surface layers of used and unused TiNi orthodontic archwires.
- To investigate the corrosion behavior of TiNi archwires in a saline environment.
- To explore electrochemical modification of TiNi archwire surfaces.
Main Methods:
- Microanalysis using optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and electron diffraction.
- Immersion and polarization corrosion tests in 0.9% NaCl solution at varying temperatures and pH.
- Electrochemical treatment to selectively etch nickel from TiNi surfaces.
Main Results:
- Used TiNi archwires showed surface discoloration due to contaminants, primarily potassium chloride (KCl) crystals.
- Both used and unused wires exhibited irregular surface morphologies with selectively dissolved nickel.
- Corrosion rates increased with higher temperatures (3-60°C) and increased acidity (pH 11-3) in NaCl solution.
- Electrochemical treatment successfully removed nickel, creating a porous, titanium-enriched surface layer.
Conclusions:
- Surface contaminants on used TiNi archwires can affect their appearance.
- TiNi archwire surfaces are prone to selective nickel dissolution.
- Environmental factors like temperature and pH significantly influence TiNi archwire corrosion.
- Electrochemical modification offers a method to enhance TiNi archwire surfaces, potentially improving tribological properties for orthodontic applications.