title: The effect of zinc oxide nanoparticles deposition for friction reduction on orthodontic wires.
abstract: BACKGROUND
  In the sliding technique, the reduced frictional forces are associated with rapid tooth movements and better control of the anchorage. Recently, wire coating with different nanoparticles has been proposed to decrease frictional forces. This in vitro study was carried out to coat stainless steel (SS) wires with zinc oxide (ZnO) nanoparticles in order to determine the effect of this coating on friction between wires and orthodontic brackets.
  
  
  METHODS
  Eighty 0.016 inch and 0.019 inch × 0.025 inch SS wires with and without ZnO nanoparticles were used in 80 orthodontic brackets (0.018 and 0.022 systems). The coated wires were analyzed by SEM and X-Ray diffraction (XRD) observations. Kinetic friction between the wires and orthodontic brackets were calculated using a universal testing machine. Frictional forces were statistically analyzed using three-way ANOVA, one-way ANOVA, Student's t-test and Tukey multiple comparison tests.
  
  
  RESULTS
  Coating with ZnO nanoparticles significantly influenced frictional force values (P < 0.0001). In 0.019 inch × 0.025 inch wires, the frictional forces were 1.6912 ± 0.18868 and 3.4485 ± 0.32389 N in the coated and uncoated wires respectively, (51% reductions). In the 0.016 inch wires, the friction values were estimated to be 1.5668 ± 0.10703 and 2.56 ± 0.34008 N in the coated and uncoated conditions, respectively, (39% reductions).
  
  
  CONCLUSIONS
  Due to the positive effects of ZnO nanoparticle coating on decreasing frictional forces, these nanoparticles might offer a novel opportunity to significantly reduce friction during tooth movement.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Tabriz University of Medical Science, Tabriz, Iran.
authors.forename: Mojghan
authors.initials: M
authors.lastname: Kachoei
authors.forename: Faranak
authors.initials: F
authors.lastname: Eskandarinejad
authors.forename: Baharak
authors.initials: B
authors.lastname: Divband
authors.forename: Masumeh
authors.initials: M
authors.lastname: Khatamian
keywords: Kinetic friction; orthodontic wires and brackets; zinc oxide nanoparticles