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Updated: May 30, 2026
Applying Dynamic Strain on Thin Oxide Films Immobilized on a Pseudoelastic Nickel-Titanium Alloy
Published on: July 28, 2020
Effect of coating on properties of esthetic orthodontic nickel-titanium wires
Masahiro Iijima1, Takeshi Muguruma, William Brantley
1Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, Health Sciences University of Hokkaido, Hokkaido, Japan. iijima@hoku-iryo-u.ac.jp
Objective:
To determine the effect of coating on the properties of two esthetic orthodontic nickel-titanium wires.
Materials And Methods:
Woowa (polymer coating; Dany Harvest) and BioForce High Aesthetic Archwire (metal coating; Dentsply GAC) with cross-section dimensions of 0.016 × 0.022 inches were selected. Noncoated posterior regions of the anterior-coated Woowa and uncoated Sentalloy were used for comparison. Nominal coating compositions were determined by x-ray fluorescence (JSX-3200, JOEL). Cross-sectioned and external surfaces were observed with a scanning electron microscope (SEM; SSX-550, Shimadzu) and an atomic force microscope (SPM-9500J2, Shimadzu). A three-point bending test (12-mm span) was carried out using a universal testing machine (EZ Test, Shimadzu). Hardness and elastic modulus of external and cross-sectioned surfaces were obtained by nanoindentation (ENT-1100a, Elionix; n = 10).
Results:
Coatings on Woowa and BioForce High Aesthetic Archwire contained 41% silver and 14% gold, respectively. The coating thickness on Woowa was approximately 10 µm, and the coating thickness on BioForce High Aesthetic Archwire was much smaller. The surfaces of both coated wires were rougher than the noncoated wires. Woowa showed a higher mean unloading force than the noncoated Woowa, although BioForce High Aesthetic Archwire showed a lower mean unloading force than Sentalloy. While cross-sectional surfaces of all wires had similar hardness and elastic modulus, values for the external surface of Woowa were smaller than for the other wires.
Conclusions:
The coating processes for Woowa and BioForce High Aesthetic Archwire influence bending behavior and surface morphology.
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