title: Maxillary arch changes during leveling and aligning with fixed appliances and low-friction ligatures.
abstract: BACKGROUND
  The aim of this study was to evaluate the changes in the transverse dimension and the perimeter of the maxillary arch produced by a low-friction system during the leveling and aligning phases of fixed appliance therapy.
  
  
  METHODS
  The low-friction protocol consisted of a combination of preadjusted brackets, superelastic nickel-titanium archwires, and nonconventional elastomeric ligatures; it was used in 20 consecutively treated patients with mild crowding.
  
  
  RESULTS
  Statistically significant increases were recorded for all dentoalveolar widths (with the exception of intermolar width measured lingually) and arch perimeter (3.5 mm on average). The increase in arch perimeter showed a significant negative relationship with the individual perimeter of the maxillary arch before treatment. No significant change was found for arch depth.
  
  
  CONCLUSIONS
  The low-friction system produced statistically significant increases in the transverse dentoalveolar width and the perimeter of the maxillary arch during the leveling and aligning phases of treatment with an average duration of 6 months.
authors.affiliation: Department of Orthodontics, University of Florence, Florence, Italy. l.franchi@odonto.unifi.it
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Franchi
authors.forename: Tiziano
authors.initials: T
authors.lastname: Baccetti
authors.forename: Matteo
authors.initials: M
authors.lastname: Camporesi
authors.forename: Massimo
authors.initials: M
authors.lastname: Lupoli
mesh_terms: D000293:Adolescent; D003722:Dental Alloys; D003724:Dental Arch / Q000033:anatomy & histology*; D003799:Dental Stress Analysis; D004548:Elasticity; D020724:Elastomers; D005260:Female; D017276:Friction; D006801:Humans; D016014:Linear Models; D008297:Male; D008310:Malocclusion / Q000628:therapy; D008437:Maxilla; D009532:Nickel; D009716:Numerical Analysis, Computer-Assisted; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D009971:Orthodontics, Corrective / Q000295:instrumentation* / Q000379:methods; D014025:Titanium
chemical_list: D003722:Dental Alloys; D020724:Elastomers; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium