On the periodontal ligament representation in orthodontic tooth movement modelisation

Orthodontic tooth movement (OTM) is the result of bone remodeling at the interface with the periodontal ligament (PDL) around a mechanically loaded tooth in response to a biomechanical stimulus. Modeling of the PDL therefore plays an important role in the process of modeling OTM. However when producing a finite element model from clinical computer tomography data, the PDL cannot be segmented and its geometry is approximated by many authors from the root geometry.
The aim of this study is to propose alternatives to a geometrical representation of the PDL using either simple spring elements between the teeth and alveolar bone or bilateral sticking contact conditions. Results consist in a comparison of the hydrostatic and Von-Mises stresses in the bone along the root as well as the strain energy used in a bone remodeling algorithm when a 1N force is applied to a single rooted tooth crown.
While both models can well represent the pressure (hydrostatic stress) transfer from the tooth to the bone, the bilateral sticking contact conditions show better results to transfer the shear stress as well as the strain energy.