title: Experiments to determine the material properties of the periodontal ligament.
abstract: PHYSIOLOGY OF THE PERIODONTAL LIGAMENT: The periodontal ligament is a soft biological tissue that controls tooth movement under physiological loads by joining tooth and alveolar bone. Its various components differ in their material properties. Their spatial configuration and interaction are responsible for the reaction of the tissue in a loading situation. Due to the combination of fluid and elastic elements the periodontal ligament shows a viscoelastic behavior typical of soft biological tissues. It is characterized by non-linearity and time dependency, and additionally depends on loading history.
  In orthodontics, external loads are applied to the tooth crowns using orthodontic appliances. Since stresses and strains in the periodontal tissue, caused by the initial tooth movement, stimulate alveolar bone remodeling and thus orthodontic tooth movement, knowledge of the material properties of the periodontal ligament is fundamental to selection of an optimal force system for targeted tooth movement.
  For this reason, typical properties of the viscoelastic material behavior of the periodontal ligament were tested experimentally in the present study, using samples from pig mandibles. This enabled the properties of force relaxation and hysteresis of this tissue, both of which depend on loading history, to be verified.
  
  
  CONCLUSIONS
  The experimental results allow characterization of the tissue and thus contribute to an understanding of the biomechanics of tooth displacement under externally applied loads.
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; D004548:Elasticity; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D010513:Periodontal Ligament / Q000033:anatomy & histology / Q000502:physiology*; D013552:Swine; D014087:Tooth Movement Techniques / Q000379:methods*; D016474:Weight-Bearing / Q000502:physiology*