title: The influence of ligation on frictional resistance to sliding during repeated displacement.
abstract: OBJECTIVE
  To determine if the type of ligation influences the frictional resistance between stainless steel wire and brackets when the wire is subjected to repeated vertical displacements.
  
  
  METHODS
  Eight different types of ligation were used to secure a length of stainless steel wire in three stainless steel twin brackets. The wire was subjected to repeated vertical displacements in a simulated extraction space. Eighty per cent of the minimum force required to overcome static friction (F-m) between the wire and brackets was applied to the wire for eight minutes and any sliding measured.
  
  
  RESULTS
  Frictional resistance to sliding was least when stainless steel ligatures twisted in a figure 8 pattern until taut then untwisted one quarter turn were used, and greatest when elastomeric modules in a figure 8 pattern (EM8) were used. The F-m difference between fully engaged standard and Super Slick elastomeric modules was significantly different (p = 0.007). The frictional resistance to sliding fell when the wire was secured with either of these two methods and subjected to vertical displacement loads. There was no significant difference in the rate of wire movement between these modules.
  
  
  CONCLUSIONS
  Repeated vertical displacement reduced the frictional resistance to sliding for all methods of ligation except EM8.
authors.affiliation: School of Dentistry, The University of Queensland, Brisbane, Australia.
authors.forename: Nathawut
authors.initials: N
authors.lastname: Sirisaowaluk
authors.forename: Olena
authors.initials: O
authors.lastname: Kravchuk
authors.forename: Christopher T C
authors.initials: CT
authors.lastname: Ho
mesh_terms: D003722:Dental Alloys / Q000737:chemistry; D020724:Elastomers / Q000737:chemistry; D017276:Friction; D006801:Humans; D008422:Materials Testing; D009068:Movement; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003722:Dental Alloys; D020724:Elastomers; D013193:Stainless Steel