title: The importance of cortical bone orthotropicity, maximum stiffness direction and thickness on the reliability of mandible numerical models.
abstract: OBJECTIVE
  To identify mechanical and geometrical variables affecting the biofidelity of numerical models of human mandible. Computed results sensibility to cortical bone orthotropy and thicknesses is investigated.
  
  
  METHODS
  Two mandible numerical models of different bone complexities are setup. In the low-complexity model, cortical bone is coupled with isotropic materials properties; constant thickness for cortical bone is adopted along the mandible structure. In the higher complexity model, the cortical bone is considered as an orthotropic material according to an independent mechanical characterization performed on fresh human dentate mandibles. Cortical thickness distribution, the values of the principal elastic moduli and principal directions of orthotropy are considered as piecewise heterogeneous. Forces for masseter (10 N), medial pterigoid (6 N), anterior (4 N) and posterior (4 N) temporalis muscles are applied to the models. Computed strains fields are compared with those experimentally measured in an independent test performed on a real human mandible in the same loading conditions.
  
  
  RESULTS
  Under closure muscles forces both models shows similar strain distribution. On the contrary, strain fields values are significantly different between the presented models.
  
  
  CONCLUSIONS
  The mandible structure is sensible to compact bone orthotropy and thickness at the facial side of condylar neck, retro molar area and at the lingual side of middle portion of the corpus in molars area, anterior margin of the ramus. In these areas, it is advisable to use orthotropic properties for cortical bone to accurately describe the strain state.
authors.affiliation: Department of Odontostomatological, Orthodontic and Surgical Disciplines, Second University of Naples, Caserta, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Apicella
authors.forename: Raffaella
authors.initials: R
authors.lastname: Aversa
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Ferro
authors.forename: Domenico
authors.initials: D
authors.lastname: Ianniello
authors.forename: Letizia
authors.initials: L
authors.lastname: Perillo
authors.forename: Antonio
authors.initials: A
authors.lastname: Apicella
mesh_terms: D000465:Algorithms; D001696:Biomechanical Phenomena; D015519:Bone Density; D003198:Computer Simulation; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D016014:Linear Models; D008334:Mandible / Q000033:anatomy & histology* / Q000502:physiology*; D008953:Models, Anatomic; D008954:Models, Biological; D003765:Models, Dental