title: Influence of initial strain on the force decay of currently available elastic chains over time.
abstract: OBJECTIVE
  To investigate the dependence of force decay on the initial strain applied to currently available elastic chains.
  
  
  METHODS
  Eight different elastic chains from eight major companies were tested for force decay over a period of 3 weeks at 50% and 100% strain. They were stored in water and thermocycled between 5°C and 55°C. An Instron 3344 was used for the force measurements.
  
  
  RESULTS
  Absolute force values at 50% strain varied between 2.3 N and 4.1 N initially, and between 0.9 N and 1.6 N after 21 days. Thus, the force decay of the elastic chains varied from 37% to 75%. At 100% strain, the force values varied between 2.9 N and 4.7 N initially, and between 1.3 N and 2.1 N after 21 days of continuous strain. The force decay varied between 39% and 67%. Most force decays between 24 hours and 21 days were not significant. This information should be taken into consideration when the appropriate elastic chain is selected for clinical use.
  
  
  CONCLUSIONS
  A wide array of elastic chains with various force levels is available. However, differences between products of greater than 100% were measured for force decay over time.
authors.affiliation: Orthodontic Department, University of Basel, Basel, Basel-Stadt, Switzerland.
authors.forename: Nora
authors.initials: N
authors.lastname: Buchmann
authors.forename: Christiane
authors.initials: C
authors.lastname: Senn
authors.forename: Judith
authors.initials: J
authors.lastname: Ball
authors.forename: Lorenz
authors.initials: L
authors.lastname: Brauchli
mesh_terms: D003799:Dental Stress Analysis; D004548:Elasticity; D020724:Elastomers; D008422:Materials Testing; D009967:Orthodontic Appliances; D019516:Orthodontic Space Closure / Q000295:instrumentation; D013997:Time Factors
chemical_list: D020724:Elastomers
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