title: Modulus of elasticity of human periodontal ligament by optical measurement and numerical simulation.
abstract: OBJECTIVE
  To determine the elastic modulus of the periodontal ligament (PDL).
  
  
  METHODS
  This study was carried out on eight human maxillary jaw segments containing central incisors. Displacements were measured under load using a laser sensing system, electronic speckle pattern interferometry (ESPI). Subsequently, finite element models presenting the same individual geometry as the respective autopsy material were developed by the software of Mimics and Ansys, based on scanning data from micro computed tomography (micro CT), to simulate tooth mobility numerically under the same force systems as were used in the experiment. Numerical force/deflection curves obtained from the models were fitted to the experimental curves by repeatedly calculating theoretical tooth deflections and varying the elasticity parameters of the human PDL.
  
  
  RESULTS
  A bilinear material parameter set was assumed to simulate tooth deflections. Mean values of E₁  =  0.04 MPa, E₂  =  0.16 MPa, and ultimate strain of ε₁₂  =  7.3% were derived for the elastic behavior of the PDL.
  
  
  CONCLUSIONS
  Force/deflection curves from the measurements showed a significant nonlinear behavior of elastic stiffness of the PDL. A bilinear material parameter set was suitably assumed to be a description of nonlinear properties of the PDL.
authors.affiliation: Department of Orthodontics, Shandong University, Jinan, People’s Republic of China. liudongxu@sdu.edu.cn
authors.forename: Liu
authors.initials: L
authors.lastname: Dong-Xu
authors.forename: Wang
authors.initials: W
authors.lastname: Hong-Ning
authors.forename: Wang
authors.initials: W
authors.lastname: Chun-Ling
authors.forename: Liu
authors.initials: L
authors.lastname: Hong
authors.forename: Sun
authors.initials: S
authors.lastname: Ping
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xiao
mesh_terms: D001696:Biomechanical Phenomena; D002102:Cadaver; D003198:Computer Simulation; D003799:Dental Stress Analysis / Q000379:methods*; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007368:Interferometry / Q000379:methods; D008334:Mandible / Q000000981:diagnostic imaging; D017711:Nonlinear Dynamics; D009716:Numerical Analysis, Computer-Assisted; D010513:Periodontal Ligament / Q000502:physiology*; D014741:Video Recording; D055114:X-Ray Microtomography