title: Cross-section dimensions and mechanical properties of esthetic orthodontic coated archwires.
abstract: BACKGROUND
  There has been continuing interest in the development and use of esthetic and effective orthodontic archwires. The aims of this study were to evaluate the inner alloy core dimensions of 4 brands of as-received esthetic coated wires and their mechanical properties before and after 21 days of oral exposure, compared with conventional stainless steel and nickel titanium wires.
  
  
  METHODS
  Four groups (Ortho Organizers, Carlsbad, Calif; TP Orthodontics, LaPorte, Ind; Orthometric, Beijing, China; and Trianeiro, Rio Claro, São Paulo, Brazil) of orthodontic archwires were tested. Five properties were evaluated: inner wire dimensions, modulus of elasticity, modulus of resilience, maximum deflection force, and load deflection curve characteristics. Images of the transverse sections from the specimens were made with a stereoscope. The inner alloy core dimensions of each wire were measured by using Image Pro Plus software (version 4.5; Media Cybernetics, Silver Spring, Md). All specimens were tested in a universal testing machine in a 3-point bending test.
  
  
  RESULTS
  Coated wires of the Ortho Organizers and Trianeiro groups showed greater reductions in their inner alloy core dimensions and produced lower loading and unloading forces and lower modulus of elasticity, modulus of resilience, and maximum deflection force values than did their control wires. Inner alloy core dimensions and the mechanical behavior of coated wires practically did not differ from the control wires in the TP Orthodontics and Orthometric groups.
  
  
  CONCLUSIONS
  The reduction on the inner alloy core dimensions to compensate for the coating thickness seems to be the variable responsible for greater changes in the mechanical properties of esthetic coated wires.
authors.affiliation: Department of Orthodontics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Dayanne Lopes
authors.initials: DL
authors.lastname: da Silva
authors.forename: Claudia Trindade
authors.initials: CT
authors.lastname: Mattos
authors.forename: Eduardo Franzotti
authors.initials: EF
authors.lastname: Sant' Anna
authors.forename: Antônio Carlos de Oliveira
authors.initials: AC
authors.lastname: Ruellas
authors.forename: Carlos Nelson
authors.initials: CN
authors.lastname: Elias
mesh_terms: D020099:Coated Materials, Biocompatible; D003722:Dental Alloys; D003799:Dental Stress Analysis; D061827:Dimensional Measurement Accuracy; D055119:Elastic Modulus; D004955:Esthetics, Dental; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D018709:Statistics, Nonparametric
chemical_list: D020099:Coated Materials, Biocompatible; D003722:Dental Alloys