title: The influence of simulated aging on the mechanical properties of orthodontic elastomeric chains without an intermodular link.
abstract: OBJECTIVE
  Orthodontic elastomeric chains are a main component in orthodontic therapy with fixed vestibular or lingual appliances. The objective of this study was to investigate the influence of artificial aging on the mechanical properties of orthodontic elastomeric chains (power chains, PCs) without an intermodular link using a test setup according to DIN EN ISO 21606:2007.
  
  
  METHODS
  In this study, 11 types of PCs supplied by seven manufacturers were investigated. Four groups with 10 specimens each were randomly generated for each type. Samples were separately mounted in a universal testing machine and extended by 300% (four times their initial length) at a crosshead rate of 100 mm/min and were held at this position for five seconds. The chain length was then reduced to three times the initial length (extension by 200%) and kept for 30 s. Then, within the control group (t = 0) and the force Fmin was recorded before extension until failure was performed and force (Fmax) and length (Lmax) at failure were determined. After prestretching, specimens of the three other groups were stored in water at 37°C with its three times initial length for one day (t = 1), 14 days (t = 2), and 28 days (t = 3), respectively. The specimens were then placed in the universal testing machine and the residual force (Fmin) measured, so as to subsequently extend them until failure at Fmax and Lmax. Data were statistically analyzed by one-way analysis of variance; the level of significance was set at p = 0.05.
  
  
  RESULTS
  Statistical analysis revealed significant differences in Fmax, Fmin, and Lmax in each group (t = 0 to t = 3) between the various manufacturers (p < 0.001). Moreover, artificial aging significantly influenced Fmax, Fmin, and Lmax (p < 0.001).
  
  
  CONCLUSIONS
  The orthodontist should consider both the mechanical properties of PCs and the duration of these appliances' application when treating patients. Artificial aging had a significant influence on the parameters we determined (p <0.001).
authors: Department of Orthodontics, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Deutschland, marc@drdittmer.de.
authors: Marc Philipp
authors: MP
authors: Dittmer
authors: Anton Phillip
authors: AP
authors: Demling
authors: Lothar
authors: L
authors: Borchers
authors: Meike
authors: M
authors: Stiesch
authors: Philipp
authors: P
authors: Kohorst
authors: Rainer
authors: R
authors: Schwestka-Polly
mesh_terms: D001696:Biomechanical Phenomena; D003799:Dental Stress Analysis; D004548:Elasticity; D020724:Elastomers; D019544:Equipment Failure Analysis; D006801:Humans; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D019516:Orthodontic Space Closure / Q000295:instrumentation*; D013718:Tensile Strength; D014087:Tooth Movement Techniques / Q000295:instrumentation*
chemical_list: D020724:Elastomers