The role of PDL-cementum enthesis in protecting PDL under masticatory loading: A finite element investigation

Abstract PURPOSE. Function of periodontal ligament-cementum enthesis (PCE) in transferring mechanical stimuli within tooth-periodontium (PDT)-bone complex was not made clear yet. This study aimed to evaluate the effects of PCE on the mechanical stimuli distribution within the PDL and alveolar bone in the tooth-PDT-bone complex under occlusal forces using finite element method (FEM). METHODS. A computed tomography (CT) based model of alveolar bone and 2nd premolar of mandible was constructed, in which the PDT was considered at the interface of alveolar bone and tooth. Under a 3MPa distributed occluso-apical masticatory load, applied over the uppermost surface of crown, the von Mises strain (vMST) and strain energy density (SED) within PDL, and von Mises stress (vMSR) and SED within alveolar bone were calculated in two situations: 1. When the PCE was absent; and 2. When the PCE was present between the PDL and cementum. RESULTS. PCE levels-off the SED and vMST within PDL by maximum values of 92 kPa and 0.04 mm/mm, respectively, compared to the model without PCE. Moreover, it increased the alveolar bone SEDs and vMSR by maximum values of 0.36 kPa and 0.63 MPa, respectively, compared to the without PCE model.CONCLUSION. By including PCE in the tooth-PDT-bone model, the mechanical stimuli shift from PDL to its surrounding alveolar bone. Thus, it can be speculated that the tooth-PDT-bone complex has the capability of, through shifting excess mechanical stimuli from PDL toward the alveolar bone, reducing the risk of PDL damage.