title: The effect of fluoride exposure on the load-deflection properties of superelastic nickel-titanium-based orthodontic archwires.
abstract: BACKGROUND
  It has been demonstrated that fluoride prophylactic agents may cause hydrogen absorption in NiTi wires and degrade their mechanical properties.
  
  
  OBJECTIVE
  To investigate the effect of a fluoride mouthwash on load-deflection characteristics of three types of nickel-titanium-based orthodontic archwires.
  
  
  METHODS
  Twenty maxillary 0.016 inch round specimens from each of the single-strand NiTi (Rematitan 'Lite'), multi-strand NiTi (SPEED Supercable) and Copper NiTi (Damon Copper NiTi) wires were selected. The specimens were kept in either 0.2% NaF or artificial saliva solutions at 37 degrees C for 24 hours (N = 10). The wire load-deflection properties were measured by a Zwick testing machine, using a three-point bending test. An un-paired student's t-test, a one-way ANOVA and a Tukey post-hoc test were used to assess statistical significance.
  
  
  RESULTS
  Immersion in NaF solution affected the load-deflection properties of NiTi wires. The unloading forces at 0.5 and 1.0 mm deflections were significantly lower in fluoride-treated specimens compared with the control groups (p < 0.05). Unloading forces at 1.5, 2.0 and 2.5 mm deflections were not statistically different between fluoride- and saliva-treated specimens (p > 0.05).
  
  
  CONCLUSIONS
  The results suggested that subjecting NiTi wires to fluoride agents decreased associated unloading forces, especially at lower deflections, and may result in delayed tooth alignment.
authors.affiliation: Dental Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran. AhrariF@mums.ac.ir
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Ahrari
authors.forename: Barat-Ali
authors.initials: BA
authors.lastname: Ramazanzadeh
authors.forename: Berahman
authors.initials: B
authors.lastname: Sabzevari
authors.forename: Ali
authors.initials: A
authors.lastname: Ahrari
mesh_terms: D000704:Analysis of Variance; D003300:Copper / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry; D003799:Dental Stress Analysis; D004548:Elasticity; D008422:Materials Testing; D009067:Mouthwashes / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry; D009969:Orthodontic Wires; D012464:Saliva, Artificial; D012969:Sodium Fluoride / Q000737:chemistry*; D018709:Statistics, Nonparametric; D014025:Titanium / Q000737:chemistry
chemical_list: D003722:Dental Alloys; D009067:Mouthwashes; D012464:Saliva, Artificial; C040654:titanium nickelide; D003300:Copper; D009532:Nickel; D012969:Sodium Fluoride; D014025:Titanium