title: Infrared spectroscopy, nano-mechanical properties, and scratch resistance of esthetic orthodontic coated archwires.
abstract: OBJECTIVE
  To evaluate the material composition, mechanical properties (hardness and elastic modulus), and scratch resistance of the coating of four commercialized esthetic orthodontic archwires.
  
  
  METHODS
  The coating composition of esthetic archwires was assessed by Fourier-transform infrared spectroscopy (FTIR). Coating hardness and elastic modulus were analyzed with instrumented nano-indentation tests. Scratch resistance of coatings was evaluated by scratch test. Coating micromorphologic characteristics after scratch tests were observed in a scanning electron microscope. Statistical differences were investigated using analysis of variance and Tukey post hoc test.
  
  
  RESULTS
  The FTIR results indicate that all analyzed coatings were markedly characterized by the benzene peak at about 1500 cm(-1). The coating hardness and elastic modulus average values ranged from 0.17 to 0.23 GPa and from 5.0 to 7.6 GPa, respectively. Scratch test showed a high coating elasticity after load removal with elastic recoveries >60%, but different failure features could be observed along the scratches.
  
  
  CONCLUSIONS
  The coatings of esthetic archwires evaluated are probably a composite of polyester and polytetrafluoroethylene. Delamination, crack propagation, and debris generation could be observed along the coating scratches and could influence its durability in the oral environment.
authors.affiliation: a   PhD student, 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.affiliation: b   Postdoctoral Researcher, Metallurgical and Materials Engineering Program, COPPE (Alberto Luiz Coimbra Institute - Graduate School and Research in Engineering), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. Professor, Civil Engineering Program, Centro Universitário de Volta Redonda (UNIFOA), Volta Redonda, Brazil.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Santos
authors.affiliation: c   Professor, Metallurgical and Materials Engineering Program, COPPE (Alberto Luiz Coimbra Institute - Graduate School and Research in Engineering), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Sérgio de Souza
authors.initials: Sde S
authors.lastname: Camargo
authors.affiliation: d   Professor, Department of Orthodontics, Universidade Federal do Rio de Janeiro, CNPQ Researcher (National Council for Scientific and Technological Development), Rio de Janeiro, Brazil.
authors.forename: Antônio Carlos de Oliveira
authors.initials: AC
authors.lastname: Ruellas
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D004954:Esthetics; D006801:Humans; D009969:Orthodontic Wires; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D020099:Coated Materials, Biocompatible
keywords: Composition; Esthetic archwires; Nano-mechanical properties; Scratch resistance