title: Tribological behaviour of orthodontic archwires under dry and wet sliding conditions in-vitro. I--Frictional behaviour.
abstract: OBJECTIVE
  To evaluate the frictional behaviour of orthodontic archwires in dry and wet conditions in-vitro.
  
  
  METHODS
  Two types of archwire materials were investigated: stainless steel and NiTi. A fretting wear tribometer fitted with an alumina ball was operated at 23 degrees C in three different environments: ambient air with 50 per cent relative humidity, 0.9 wt. per cent sodium chloride solution, and deionised water.
  
  
  RESULTS
  NiTi archwires sliding against alumina exhibited high coefficients of friction (about 0.6) in the three environments. Stainless steel archwires sliding against alumina had relatively low coefficients of friction (0.3) in the solutions, but high coefficients (0.8) in air.
  
  
  CONCLUSIONS
  The low frictional forces of the stainless steel wires sliding against alumina in the solutions were due to a lubricating effect of the solutions and corrosion-wear debris. The high frictional forces between the NiTi wires and alumina are attributed to an abrasive interfacial transfer film between the wires and alumina.
authors.affiliation: Departments of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Abdenacer
authors.initials: A
authors.lastname: Berradja
authors.forename: Guy
authors.initials: G
authors.lastname: Willems
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Celis
mesh_terms: D000388:Air; D000537:Aluminum Oxide / Q000737:chemistry; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D003890:Desiccation; D017276:Friction; D006801:Humans; D006813:Humidity; D008153:Lubrication; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires; D012965:Sodium Chloride / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D003722:Dental Alloys; D014867:Water; C040654:titanium nickelide; D013193:Stainless Steel; D012965:Sodium Chloride; D009532:Nickel; D014025:Titanium; D000537:Aluminum Oxide