title: Three palatal arches used to correct posterior dental crossbites.
abstract: OBJECTIVE
  To assess the force, resilience, and elasticity modulus produced by the Coffin appliance, "W" arch, and quad-helix made with 0.032-inch and 0.036-inch stainless steel wire.
  
  
  METHODS
  Two groups of 15 arches were made as Coffin appliances, two groups of 15 arches were made as "W" arches, and two groups of 15 arches were made as quad-helices. One group of each appliance was formed in 0.032-inch and one group in 0.036-inch stainless steel wire. All arches (6 groups of 15 each) were submitted to compression trials in the mechanical testing machine EMIC DL-10000, simulating 5-, 8-, 10-, and 12-mm activation. The force and resilience means received a one-way ANOVA statistical analysis.
  
  
  RESULTS
  The results showed that the mechanical properties depended on the shape of the appliance, the diameter of the wire used, and the amount of activation.
  
  
  CONCLUSIONS
  The three appliances assessed produce appropriate forces for orthodontic treatment as long as they are correctly planned during clinical application.
authors.affiliation: Department of Orthodontics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil. flima.ez@terra.com.br
authors.forename: Fernando Lima
authors.initials: FL
authors.lastname: Martinelli
authors.forename: Priscilla Sobral
authors.initials: PS
authors.lastname: Couto
authors.forename: Antonio Carlos Oliveira
authors.initials: AC
authors.lastname: Ruellas
mesh_terms: D000704:Analysis of Variance; D019245:Compressive Strength; D003799:Dental Stress Analysis; D004548:Elasticity; D008310:Malocclusion / Q000628:therapy*; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances; D009969:Orthodontic Wires; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D013193:Stainless Steel; D018709:Statistics, Nonparametric
chemical_list: D013193:Stainless Steel