title: Mechanical testing and finite element analysis of orthodontic teardrop loop.
abstract: BACKGROUND
  Understanding how teeth move in response to mechanical loads is an important aspect of orthodontic treatment. Treatment planning should include consideration of the appliances that will meet the desired loading of the teeth to result in optimized treatment outcomes. The purpose of this study was to evaluate the use of computer simulation to predict the force and the torsion obtained after the activation of tear drop loops of 3 heights.
  
  
  METHODS
  Seventy-five retraction loops were divided into 3 groups according to height (6, 7, and 8 mm). The loops were subjected to tensile load through displacements of 0.5, 1.0, 1.5, and 2.0 mm, and the resulting forces and torques were recorded. The loops were designed in AutoCAD software(2005; Autodesk Systems, Alpharetta, GA), and finite element analysis was performed with Ansys software(version 7.0; Swanson Analysis System, Canonsburg, PA). Statistical analysis of the mechanical experiment results was obtained by ANOVA and the Tukey post-hoc test (P < .01). The correlation test and the paired t test (P < .05) were used to compare the computer simulation with the mechanical experiment.
  
  
  CONCLUSIONS
  The computer simulation accurately predicted the experimentally determined mechanical behavior of tear drop loops of different heights and should be considered an alternative for designing orthodontic appliances before treatment.
authors.affiliation: Department of Orthodontics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. melisarc@uol.com.br
authors.forename: Maria Elisa Rodrigues
authors.initials: ME
authors.lastname: Coimbra
authors.forename: Norman Duque
authors.initials: ND
authors.lastname: Penedo
authors.forename: Jayme Pereira
authors.initials: JP
authors.lastname: de Gouvêa
authors.forename: Carlos Nelson
authors.initials: CN
authors.lastname: Elias
authors.forename: Mônica Tirre
authors.initials: MT
authors.lastname: de Souza Araújo
authors.forename: Paulo Guilherme
authors.initials: PG
authors.lastname: Coelho
mesh_terms: D000704:Analysis of Variance; D003198:Computer Simulation; D003722:Dental Alloys; D003799:Dental Stress Analysis / Q000379:methods*; D020342:Finite Element Analysis; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D013193:Stainless Steel; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D014087:Tooth Movement Techniques; D054159:Torsion, Mechanical
chemical_list: D003722:Dental Alloys; D013193:Stainless Steel