title: Effect of archwire cross-section changes on force levels during complex tooth alignment with conventional and self-ligating brackets.
abstract: BACKGROUND
  Our objective was to investigate the effect of archwire cross-section increases on the levels of force applied to teeth during complex malalignment correction with various archwire-bracket combinations using an experimental biomechanical setup.
  
  
  METHODS
  The study comprised 3 types of orthodontic brackets: (1) conventional ligating brackets (Victory Series [3M Unitek, Monrovia, Calif] and Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo]), (2) self-ligating brackets (SmartClip, a passive self-ligating bracket [3M Unitek]; and Time3 [Rocky Mountain Orthodontics, Denver, Colo] and SPEED [Strite Industries, Cambridge, Ontario, Canada], both active self-ligating brackets), and (3) a conventional low-friction bracket (Synergy [Rocky Mountain Orthodontics]). All brackets had a nominal 0.022-in slot size. The brackets were combined with 0.014-in and 0.016-in titanium memory wires, Therma-Ti archwires (American Orthodontics, Sheboygan, Wis). The archwires were tied to the conventional brackets with both stainless steel ligatures of size 0.010-in and elastomeric rings. A malocclusion of the maxillary central incisor displaced 2 mm gingivally (x-axis) and 2 mm labially (z-axis) was simulated.
  
  
  RESULTS
  The forces recorded when using the 0.014-in archwires ranged from 1.7 ± 0.1 to 5.0 ± 0.3 N in the x-axis direction, and from 1.2 ± 0.1 to 5.5 ± 0.3 N in the z-axis direction. When we used the 0.016-in archwires, the forces ranged from 2.6 ± 0.1 to 6.0 ± 0.3 N in the x-axis direction, and from 2.0 ± 0.2 to 6.0 ± 0.4 N in the z-axis direction. Overall, the increases ranged from 16.0% to 120.0% in the x-axis and from 10.4% to 130.0% in the z-axis directions.
  
  
  CONCLUSIONS
  Increasing the cross section of the wire increased the force level invariably with all brackets. Wires of size 0.014 in produced relatively high force levels, and the force level increased with 0.016-in wires.
authors.affiliation: Associate professor, Orthodontic Department, Faculty of Dentistry, University of Mansoura, Mansoura, Egypt. Electronic address: mmontasser11@yahoo.com.
authors.forename: Mona A
authors.initials: MA
authors.lastname: Montasser
authors.affiliation: Senior researcher, Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.
authors.forename: Ludger
authors.initials: L
authors.lastname: Keilig
authors.affiliation: Associate professor, Department of Orthodontics, School of Dentistry, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Tarek
authors.initials: T
authors.lastname: El-Bialy
authors.affiliation: Senior researcher, Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Reimann
authors.affiliation: Professor and head, Department of Orthodontics, School of Dentistry, University of Bonn, Bonn, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Jäger
authors.affiliation: Cendres+Métaux Endowed professor, Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bourauel
mesh_terms: D001696:Biomechanical Phenomena; D003722:Dental Alloys / Q000737:chemistry; D020724:Elastomers / Q000737:chemistry; D017276:Friction; D006801:Humans; D007180:Incisor / Q000473:pathology; D008422:Materials Testing; D008437:Maxilla; D009532:Nickel / Q000737:chemistry; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D014087:Tooth Movement Techniques / Q000295:instrumentation*
chemical_list: D003722:Dental Alloys; D020724:Elastomers; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium