title: Force levels in complex tooth alignment with conventional and self-ligating brackets.
abstract: BACKGROUND
  The force applied to the teeth is a variable of orthodontic treatment that can be controlled. Poor control of the applied force can lead to adverse biologic effects as well as undesirable tooth movements. The selected archwire-bracket combination is a primary determining factor in the force level applied to a tooth during orthodontic treatment. The aim of this research was to use an experimental biomechanical setup to measure forces generated during complex orthodontic tooth movements with various archwire-bracket combinations.
  
  
  METHODS
  The materials consisted of 3 types of 0.022-in slot orthodontic brackets: (1) conventional brackets (Victory Series [3M Unitek, Monrovia, Calif] and Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo]), (2) self-ligating brackets (SmartClip [3M Unitek] and Time3 [American Orthodontics, Shegoygan, Wis]), and (3) a conventional low-friction bracket (Synergy [Rocky Mountain Orthodontics]); and 4 archwire types: (1) 0.012-in stainless steel (3M Unitek), (2) 0.0155-in coaxial (Advanced Orthodontics [Näpflein, Düsseldorf, Germany]), (3) 0.012-in Orthonol (Rocky Mountain Orthodontics), and (4) 0.012-in Thermalloy (Rocky Mountain Orthodontics). Stainless steel ligatures and elastomeric rings were used. The materials were used in different combinations in a simulated malocclusion that represented a maxillary central incisor displaced 2 mm gingivally (x-axis) and 2 mm labially (z-axis).
  
  
  RESULTS
  The lowest forces were measured when the brackets were combined with either the coaxial or the Thermalloy archwires; the forces ranged from 3.4 ± 0.2 to 0.7 ± 0.1 N in the x-axis direction, and from 4.5 ± 0.3 to 0.5 ± 0.1 N in the z-axis direction. The highest forces were measured in combination with stainless steel archwires; the forces ranged from 6.3 ± 0.3 to 3.0 ± 0.1 N in the x-axis direction, and from 6.3 ± 0.3 to 1.7 ± 0.1 N in the z-axis direction.
  
  
  CONCLUSIONS
  We recommend 0.0155-in coaxial and 0.012-in Thermalloy archwires for leveling and alignment. Elastomeric rings, when used with conventional brackets, increased the force applied to the teeth.
authors.affiliation: Orthodontic Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt. mmontasser11@yahoo.com
authors.forename: Mona A
authors.initials: MA
authors.lastname: Montasser
authors.forename: Tarek
authors.initials: T
authors.lastname: El-Bialy
authors.forename: Ludger
authors.initials: L
authors.lastname: Keilig
authors.forename: Susanne
authors.initials: S
authors.lastname: Reimann
authors.forename: Andreas
authors.initials: A
authors.lastname: Jäger
authors.forename: Christoph
authors.initials: C
authors.lastname: Bourauel
mesh_terms: D001696:Biomechanical Phenomena; D003487:Cyanoacrylates / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry; D001840:Dental Bonding; D003799:Dental Stress Analysis; D020724:Elastomers / Q000737:chemistry; D017276:Friction; D006801:Humans; D007180:Incisor / Q000473:pathology; D008310:Malocclusion / Q000473:pathology; D008953:Models, Anatomic; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D019279:Resin Cements / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D014087:Tooth Movement Techniques / Q000295:instrumentation*
chemical_list: D003487:Cyanoacrylates; D003722:Dental Alloys; D020724:Elastomers; D019279:Resin Cements; D013193:Stainless Steel