title: Effects of sliding velocity on friction: an in vitro study at extremely low sliding velocity approximating orthodontic tooth movement.
abstract: OBJECTIVE
  To evaluate the effects of sliding velocity on friction, particularly at extremely low sliding velocity approximating orthodontic tooth movement.
  
  
  METHODS
  Stainless-steel (SS) 0.022-inch preadjusted brackets and 0.016- and 0.016×0.022-inch SS wires and superelastic nickel-titanium 0.016×0.022-inch wires were used for this test. The wire was secured in a SS preadjusted bracket with an elastomeric module. One end of the wire was pulled upward 1.5 mm at a speed of 5.0×10(-7), 1.0×10(-5), 1.0×10(-4), 1.0×10(-3), 1.0×10(-2), and 1.0×10(-1) mm/s by the micrometer. The measurements were conducted 10 times and averaged. Tukey-Kramer tests were used to compare the mean differences of each testing measurement among the different sliding velocities.
  
  
  RESULTS
  The frictional forces tended to increase as the sliding velocity decreased. The mean frictional force for 5.0×10(-7) mm/s sliding velocity (approximating orthodontic tooth movement) was 106.8 cN in 0.016×0.022-inch SS wires, almost double the 1.0×10(-1) mm/s sliding velocity.
  
  
  CONCLUSIONS
  The effects of sliding velocity cannot be ignored when we estimate frictional forces in clinical orthodontics.
authors.affiliation: a  Resident, Section of Orthodontics, Graduate School of Dental Science, Kyushu University, Fukuoka, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Yanase
authors.forename: Hideki
authors.initials: H
authors.lastname: Ioi
authors.forename: Masato
authors.initials: M
authors.lastname: Nishioka
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takahashi
mesh_terms: D001696:Biomechanical Phenomena; D003722:Dental Alloys / Q000737:chemistry; D004548:Elasticity; D020724:Elastomers / Q000737:chemistry; D017276:Friction; D006801:Humans; D009068:Movement; D009532:Nickel / Q000737:chemistry; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry; D014070:Tooth / Q000502:physiology*; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods*
chemical_list: D003722:Dental Alloys; D020724:Elastomers; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium