title: Does self-ligating brackets type influence the hysteresis, activation and deactivation forces of superelastic NiTi archwires?
abstract: OBJECTIVE
  To compare hysteresis, activation and deactivation forces produced by first-order deformation of Contour 0.014-in NiTi wire (Aditek, Brazil) in four brands of self-ligating brackets: Damon MX, Easy Clip, Smart Clip and In-Ovation.
  
  
  METHODS
  Activation and deactivation forces were measured in an Instron universal tensile machine at 3 mm/minute speed to a total displacement of 4 mm. Tests were repeated eight times for each bracket/wire combination. Statistical analysis comprised ANOVA and Tukey's multiple comparisons test.
  
  
  RESULTS
  Using a 4-mm deformation, mean activation forces increased in the following order: Damon = 222 gf, Easy Clip = 228 gf, In-Ovation = 240 gf and Smart Clip = 306 gf. The same order was observed for mean hysteresis values, i.e., 128 gf, 140 gf, 150 gf and 206 gf, respectively. The respective values of deactivation forces for the Damon, Easy Clip, In-Ovation and Smart Clip brackets were 94 gf, 88 gf, 90 gf and 100 gf.
  
  
  CONCLUSIONS
  Brackets with higher activation forces were accompanied by higher hysteresis values, which resulted in clinically similar deactivation forces, regardless of the type of self-ligating brackets used.
authors.affiliation: Department of Orthodontics, School of Dentistry, University of São Paulo.
authors.forename: José
authors.initials: J
authors.lastname: Rino Neto
authors.forename: Gilberto Vilanova
authors.initials: GV
authors.lastname: Queiroz
authors.forename: João Batista
authors.initials: JB
authors.lastname: de Paiva
authors.forename: Rafael Yagüe
authors.initials: RY
authors.lastname: Ballester
mesh_terms: D000704:Analysis of Variance; D003722:Dental Alloys / Q000737:chemistry*; D004548:Elasticity; D008422:Materials Testing / Q000379:methods; D009532:Nickel / Q000737:chemistry*; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013314:Stress, Mechanical; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry*
chemical_list: D003722:Dental Alloys; D009532:Nickel; D014025:Titanium
keywords: Corrective orthodontics; Orthodontic brackets; Orthodontic wires