title: Tensile properties of orthodontic elastomeric ligatures.
abstract: BACKGROUND
  Tensile properties of elastomeric ligatures become important when efficiency of orthodontic appliances is considered.
  
  
  OBJECTIVE
  The aim of this study was to compare tensile strength, extension to tensile strength, toughness and modulus of elasticity of elastomeric ligatures in both the as--received condition and after 28 days of immersion in the simulated oral environment. Furthermore, the changes that occurred in tensile properties of each brand of ligatures after 28 days were evaluated.
  
  
  METHODS
  Experimental-laboratory based.
  
  
  METHODS
  Elastomeric ligatures were obtained from different companies and their tensile properties were measured using Zwick testing machine in both the as-received condition and after 28 days of immersion in the simulated oral environment.
  
  
  METHODS
  The data were analyzed using independent sample t-tests, analysis of variance and Tukey tests.
  
  
  RESULTS
  After 28 days, all the ligatures experienced a significant decrease in tensile strength, extension to tensile strength and toughness ( P < 0.05), whereas modulus of elasticity increased in some groups and decreased in others. There were significant differences in tensile properties of different brands of ligatures in both conditions ( P < 0.05), with the exception of modulus of elasticity after 28 days.
  
  
  CONCLUSIONS
  The decrease in strength properties of elastomeric ligatures shows that they should be replaced at each appointment to reduce the risk of rupture. There are significant differences in tensile properties of different brands of ligatures, which should be considered during selection of these products.
authors.affiliation: Department of Orthodontics, School of Dentistry, Mashhad University of Medical Sciences, Dental Research Center, Mashhad, Iran.
authors.forename: F
authors.initials: F
authors.lastname: Ahrari
authors.forename: T
authors.initials: T
authors.lastname: Jalaly
authors.forename: M
authors.initials: M
authors.lastname: Zebarjad
mesh_terms: D000704:Analysis of Variance; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D020724:Elastomers; D009967:Orthodontic Appliances; D012464:Saliva, Artificial; D018709:Statistics, Nonparametric; D013718:Tensile Strength
chemical_list: D020724:Elastomers; D012464:Saliva, Artificial