title: Evaluation of force released by deflection of orthodontic wires in conventional and self-ligating brackets.
abstract: The aim of the study was to evaluate deflection forces of rectangular orthodontic wires in conventional (MorelliTM), active (In-Ovation RTM) and passive (Damon 3MXTM) self-ligating brackets.
  Two brands of stainless steel and nickel-titanium (NiTi) wires (MorelliTM and GACTM), in addition to OrmcoTM copper-nickel-titanium wires were used. Specimens were assembled in a clinical simulation device especially designed for this study and tested in an Instron universal testing machine. For the testing procedures, an acrylic structure representative of the maxillary right central incisor was lingually moved in activations of 0 to 1 mm, with readings of the force released by deflection in unloading of 0.5, 0.8 and 1 mm at a constant speed of 2 mm/min. Inter-bracket forces with stainless steel, NiTi and CuNiTi were individually compared by two-way ANOVA, followed by Tukey's tests.
  Results showed that there were lower forces in conventional brackets, followed by active and passive self-ligating brackets. Within the brands, only for NiTi wires, the MorelliTM brand presented higher forces than GACTM wires.
  Bracket systems provide different degrees of deflection force, with self-ligating brackets showing the highest forces.
authors.affiliation: PhD resident in Orthodontics, School of Dentistry, Universidade de São Paulo, Bauru/SP, Brazil.
authors.forename: Rodrigo Hitoshi
authors.initials: RH
authors.lastname: Higa
authors.affiliation: DDS, School of Dentistry, University of São Paulo, Bauru/SP, Brazil.
authors.forename: Nayara Thiago
authors.initials: NT
authors.lastname: Semenara
authors.affiliation: Full professor, Department of Orthodontics, School of Dentistry, Universidade de São Paulo, Bauru/SP , Brazil.
authors.forename: José Fernando Castanha
authors.initials: JF
authors.lastname: Henriques
authors.affiliation: Full professor, Department of Orthodontics, School of Dentistry, Universidade de São Paulo, Bauru/SP , Brazil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Janson
authors.affiliation: Professor, Hospital for Rehabilitation of Craniofacial Anomalies, Universidade de São Paulo, Bauru/SP , Brazil.
authors.forename: Renata
authors.initials: R
authors.lastname: Sathler
authors.affiliation: Full professor, Universidade Norte do Paraná, Londrina/PR, Brazil.
authors.forename: Thais Maria Freire
authors.initials: TM
authors.lastname: Fernandes
mesh_terms: D000497:Alloys; D003799:Dental Stress Analysis; D006801:Humans; D055595:Mechanical Phenomena; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013193:Stainless Steel
chemical_list: D000497:Alloys; D013193:Stainless Steel; C013616:nitinol