title: Investigation into the effects of stainless steel ligature ties on the mechanical characteristics of conventional and self-ligated brackets subjected to torque.
abstract: OBJECTIVE
  Torque is applied to orthodontic brackets in order to alter the buccal-lingual angulation of a tooth. One factor that can affect torque is the ligation mode used to retain the archwire in the bracket slot. The objective of this study was to investigate the effects of stainless steel ligation on torque expression and bracket deformation.
  
  
  METHODS
  This study utilized 60 upper right central incisor Damon Q brackets and 60 Ormco Orthos Twin brackets. The brackets used in this study were subdivided into four groups: (1) Damon Q ligated with SS ligature; (2) Damon Q with the sliding bracket door; (3) Orthos Twin bracket ligated with SS wire; and (4) Orthos Twin ligated with elastic ties. All brackets were tested using an orthodontic torque simulating device that applied archwire rotation from 0° to 45°.
  
  
  RESULTS
  All brackets ligated with stainless steel ties exhibited greater torque expression and less deformation than brackets without stainless steel ties. As well, Damon Q brackets exhibit less bracket deformation than Orthos Twin brackets.
  
  
  CONCLUSIONS
  Stainless steel ties can reduce the amount of plastic deformation for both types of brackets used in this study.
authors.affiliation: School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alta, Canada.
authors.forename: Hussam
authors.initials: H
authors.lastname: Al Fakir
authors.affiliation: Faculty of Engineering, University of Alberta, Edmonton, Alta, Canada.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Carey
authors.affiliation: Faculty of Engineering, University of Alberta, Edmonton, Alta, Canada.
authors.forename: Garrett W
authors.initials: GW
authors.lastname: Melenka
authors.affiliation: Faculty of Engineering, University of Alberta, Edmonton, Alta, Canada.
authors.forename: David S
authors.initials: DS
authors.lastname: Nobes
authors.affiliation: Division of Orthodontics, School of Dentistry, Faculty of Medicine and Dentistry, and Joint Appointment, Department of Mathematical and Statistical Sciences, Faculty of Science, University of Alberta, Edmonton, Alta, Canada.
authors.forename: Giseon
authors.initials: G
authors.lastname: Heo
authors.affiliation: School of Dentistry, Department of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alta, Canada.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Major
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D004548:Elasticity; D006801:Humans; D008422:Materials Testing; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D012399:Rotation; D013193:Stainless Steel / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D014087:Tooth Movement Techniques / Q000295:instrumentation; D019415:Torque
chemical_list: D003722:Dental Alloys; D013193:Stainless Steel
keywords: Orthodontic brackets; bracket deformation; conventional ligation; self-ligation; torque expression