title: Photoelastic analysis of forces generated by T-loop springs made with stainless steel or titanium-molybdenum alloy.
abstract: BACKGROUND
  The purpose of this study was to use photoelastic analysis to compare the system of forces generated by retraction T-loop springs made with stainless steel and titanium-molybdenum alloy (TMA) (Ormco, Glendora, Calif) with photoelastic analysis.
  
  
  METHODS
  Three photoelastic models were used to evaluate retraction T-loop springs with the same preactivations in 2 groups. In group 1, the loop was constructed with a stainless steel wire, and 2 helicoids were incorporated on top of the T-loop; in group 2, it was made with TMA and no helicoids.
  
  
  RESULTS
  Upon using the qualitative analysis of the fringe order in the photoelastic model, it was observed that the magnitude of force generated by the springs in group 1 was significantly higher than that in group 2. However, both had symmetry for the active and reactive units related to the system of force.
  
  
  CONCLUSIONS
  Both springs had the same mechanical characteristics. TMA springs showed lower force levels.
authors: Faculdade de Odontologia de Araraquara, Universidade Estadual Paulista, Araraquara, São Paulo, Brazil.
authors: Luiz Guilherme Martins
authors: LG
authors: Maia
authors: Mila Leite
authors: ML
authors: de Moraes Maia
authors: André
authors: A
authors: da Costa Monini
authors: Alexandre Protásio
authors: AP
authors: Vianna
authors: Luiz Gonzaga
authors: LG
authors: Gandini
mesh_terms: D000497:Alloys; D001718:Birefringence; D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000379:methods*; D004548:Elasticity; D006801:Humans; D008422:Materials Testing; D008962:Models, Theoretical; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D010781:Photography; D036301:Qualitative Research; D013193:Stainless Steel; D013314:Stress, Mechanical
chemical_list: D000497:Alloys; D003722:Dental Alloys; C525450:titanium molybdenum alloy; D013193:Stainless Steel