title: Photoelastic analysis of stress generated by wires when conventional and self-ligating brackets are used: a pilot study.
abstract: OBJECTIVE
  By means of a photoelastic model, this study analyzed the stress caused on conventional and self-ligating brackets with expanded arch wires.
  
  
  METHODS
  Standard brackets were adhered to artificial teeth and a photoelastic model was prepared using the Interlandi 19/12 diagram as base. Successive activations were made with 0.014-in and 0.018-in rounded cross section Nickel-Titanium wires (NiTi) and 0.019 x 0.025-in rectangular stainless steel wires all of which made on 22/14 Interlandi diagram. The model was observed on a plane polariscope--in a dark field microscope configuration--and photographed at each exchange of wire. Then, they were replaced by self-ligating brackets and the process was repeated. Analysis was qualitative and observed stress location and pattern on both models analyzed.
  
  
  CONCLUSIONS
  Results identified greater stress on the region of the apex of premolars in both analyzed models. Upon comparing the stress between models, a greater amount of stress was found in the model with conventional brackets in all of its wires. Therefore, the present pilot study revealed that alignment of wires in self-ligating brackets produced lower stress in periodontal tissues in expansive mechanics.
authors.affiliation: School of Dentistry, University of Araras.
authors.forename: Guilherme Caiado
authors.initials: GC
authors.lastname: Sobral
authors.affiliation: Department of Orthodontics, UNIARARAS.
authors.forename: Mário
authors.initials: M
authors.lastname: Vedovello Filho
authors.affiliation: Department of Orthodontics, UNIARARAS.
authors.forename: Viviane Veroni
authors.initials: VV
authors.lastname: Degan
authors.affiliation: UNIARARAS.
authors.forename: Milton
authors.initials: M
authors.lastname: Santamaria
mesh_terms: D001696:Biomechanical Phenomena; D003722:Dental Alloys / Q000737:chemistry; D006801:Humans; D008334:Mandible; D008422:Materials Testing; D008953:Models, Anatomic; D009532:Nickel / Q000737:chemistry; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets / Q000145:classification*; D009969:Orthodontic Wires; D010781:Photography / Q000379:methods; D010865:Pilot Projects; D013193:Stainless Steel; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D019227:Tooth Apex / Q000502:physiology; D014092:Tooth Root / Q000502:physiology
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium