title: In vitro friction of stainless steel arch wire-bracket combinations in air and different aqueous solutions.
abstract: OBJECTIVE
  To investigate the in vitro coefficient of friction of stainless steel arch wire-bracket combinations under fretting contact test conditions performed in air and in different aqueous solutions, like Ringer solution, Ringer with addition of a buffer, Ringer with addition of glucose, and Coca Cola.
  
  
  METHODS
  The fretting test set-up used allowed to control on-line the contact configuration and the positioning of the contacting parts. A specific positioning method was used to achieve a parallel alignment of arch wire and bracket slot. The effect of arch wire size, roughness, and test environment were investigated.
  
  
  RESULTS
  It was found that the aqueous solutions act as a lubricant compared to air. Friction was affected by the arch wire width while the roughness was found to have a limited effect. Stainless steel 0.018'' x 0.025'' arch wires exhibited higher frictional forces than stainless steel 0.017'' x 0.025'' arch wires on sliding against stainless steel 0.018'' x 0.025'' brackets in the selected test environments when tested under identical fretting test conditions. The wear damage on the arch wire after these in-vitro fretting tests was investigated. It revealed that these in-vitro tests are governed by a competition between oxidational wear and abrasive wear taking place at contact areas between brackets and arch wires.
  
  
  CONCLUSIONS
  For all aqueous solutions a lower coefficient of friction was found compared to tests performed in ambient air.
authors.affiliation: Department of Orthodontics, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Al-Khatib
authors.forename: A
authors.initials: A
authors.lastname: Berradja
authors.forename: J-P
authors.initials: JP
authors.lastname: Celis
authors.forename: G
authors.initials: G
authors.lastname: Willems
mesh_terms: D000388:Air; D002021:Buffers; D002253:Carbonated Beverages; D003799:Dental Stress Analysis / Q000295:instrumentation; D017276:Friction; D005947:Glucose / Q000737:chemistry; D006801:Humans; D007552:Isotonic Solutions / Q000737:chemistry; D008153:Lubrication; D008422:Materials Testing; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D010084:Oxidation-Reduction; D000077331:Ringer's Solution; D013193:Stainless Steel / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D002021:Buffers; D007552:Isotonic Solutions; D013193:Stainless Steel; D000077331:Ringer's Solution; D005947:Glucose