title: Nickel release from orthodontic retention wires-the action of mechanical loading and pH.
abstract: Nickel (Ni) is a potent sensitizer and may induce innate and adaptive immune responses. Ni is an important component of orthodontic appliances (8-50 wt%). Due to chemical and mechanical factors in the oral environment, Ni is released from these appliances. Retention wires are in situ for a long period of time.
  
  
  OBJECTIVE
  To quantitatively evaluate the influence of mechanical loading and pH on the nickel release from orthodontic retention wires.
  
  
  METHODS
  Five different types of multi-stranded wires (Original Wildcat, Noninium, Lingual retainer, Dentaflex 3-s, Dentaflex 6-s), were submersed for 24 h in either 10 ml of distilled water or lactic acid, both submitted to cyclic loading in a 3-point bending test (0×, 1000×, 10,000×). The solutions were analyzed by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS), and the data was statistically analyzed (ANOVA, p<0.05).
  
  
  RESULTS
  Mechanical loading has a strong effect on the Ni release from orthodontic retention wires, especially in distilled water. Acidity has more impact on Ni release when compared to mechanical loading. Manganese-steel "Ni-free" wires released quantifiable amounts of Ni due to trace elements of Ni within the wire.
  
  
  CONCLUSIONS
  All investigated wires release considerable amounts of Ni to which exposure may have biological implications.
authors.affiliation: Department of Dental Materials Sciences, ACTA, University of Amsterdam, The Netherlands. A.Milheiro@acta.nl
authors.forename: Ana
authors.initials: A
authors.lastname: Milheiro
authors.forename: Cornelis
authors.initials: C
authors.lastname: Kleverlaan
authors.forename: Joris
authors.initials: J
authors.lastname: Muris
authors.forename: Albert
authors.initials: A
authors.lastname: Feilzer
authors.forename: Prem
authors.initials: P
authors.lastname: Pallav
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D004058:Diffusion; D055119:Elastic Modulus; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry*; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D018583:Pliability; D013052:Spectrometry, X-Ray Emission; D013054:Spectrophotometry, Atomic; D013193:Stainless Steel / Q000737:chemistry; D013232:Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D003722:Dental Alloys; D014867:Water; D013193:Stainless Steel; D013232:Steel; D019344:Lactic Acid; D009532:Nickel