title: Effect of coating on properties of esthetic orthodontic nickel-titanium wires.
abstract: OBJECTIVE
  To determine the effect of coating on the properties of two esthetic orthodontic nickel-titanium wires.
  
  
  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.
authors.affiliation: Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, Health Sciences University of Hokkaido, Hokkaido, Japan. iijima@hoku-iryo-u.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iijima
authors.forename: Takeshi
authors.initials: T
authors.lastname: Muguruma
authors.forename: William
authors.initials: W
authors.lastname: Brantley
authors.forename: Han-Cheol
authors.initials: HC
authors.lastname: Choe
authors.forename: Susumu
authors.initials: S
authors.lastname: Nakagaki
authors.forename: Satish B
authors.initials: SB
authors.lastname: Alapati
authors.forename: Itaru
authors.initials: I
authors.lastname: Mizoguchi
mesh_terms: D002713:Chlorine / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D055119:Elastic Modulus; D004853:Epoxy Resins / Q000737:chemistry; D004955:Esthetics, Dental; D006047:Gold Alloys / Q000737:chemistry; D006244:Hardness; D006801:Humans; D021621:Imaging, Three-Dimensional; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires; D010984:Platinum / Q000737:chemistry; D018583:Pliability; D012834:Silver / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D003722:Dental Alloys; D004853:Epoxy Resins; D006047:Gold Alloys; C040654:titanium nickelide; D012834:Silver; D010984:Platinum; D002713:Chlorine; D009532:Nickel; D014025:Titanium