title: Determination of the mechanical properties of the periodontal ligament in a uniaxial tensional experiment.
abstract: BACKGROUND
  The periodontal ligament is a soft connective tissue which joins the tooth root to the alveolus and thus provides for anchorage of the tooth in the alveolar bone. Due to its composition of elastic and viscous components, this tissue displays viscoelastic material properties. In a previous study [4], in vitro experiments revealed typical viscoelastic material properties of the periodontal ligament in samples from pig mandibles. These properties included force relaxation, hysteresis, and dependence on loading history.
  
  
  METHODS
  Based on those experiments, a dependence of tooth displacement on loading velocity was registered in the present study and the stress-strain behavior of the periodontal ligament was examined until the tissue ruptured. For this purpose, segments of the periodontal ligament taken from anterior teeth from the pig mandible were tested in a purpose-developed clamping fixture in a uniaxial tensional experiment.
  
  
  RESULTS
  It was found that the initial phase of the stress-strain curve in particular was dependent on loading velocity and that the shape of the hysteresis curve was subject to a variation in loading velocity. The stress-strain behavior of the periodontal ligament was characterized, divided into several phases, and the elastic modulus of the initial and the linear phase of the curve was determined at different loading velocities.
  
  
  CONCLUSIONS
  Knowledge of the material properties of the periodontal ligament is fundamental to an understanding of orthodontic tooth movement and thus to selection of an optimal force system for orthodontic treatment.
authors.affiliation: Department of Orthodontics, University of Ulm, Germany. christina.dorow@medizin.uni-ulm.de
authors.forename: Christina
authors.initials: C
authors.lastname: Dorow
authors.forename: Natasa
authors.initials: N
authors.lastname: Krstin
authors.forename: Franz-Günter
authors.initials: FG
authors.lastname: Sander
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D066298:In Vitro Techniques; D008334:Mandible; D010513:Periodontal Ligament / Q000502:physiology*; D013552:Swine; D013718:Tensile Strength; D014087:Tooth Movement Techniques; D016474:Weight-Bearing / Q000502:physiology