Effect of Oval Posts on Stress Distribution in Endodontically Treated Teeth: A Three-Dimensional Finite Element Analysis

In post-core crown restorations, the use of prefabricated composite posts concentrate stress at the cervical region and the use of metal posts (prefabricated and customized posts) concentrates stress at the interfaces. Fiber reinforced composite posts (FRCs) with oval cross-section (oval posts) were proposed for post-core crown restorations to reduce the stress levels at the cervical region. The aim of the present study was to investigate the impact of oval cross-section composite posts on stress distribution of premolar with oval-shaped canal by using three-dimensional (3D) finite element analysis.
An extracted premolar tooth was mounted, sectioned, and photographed to create a 3D model. The surrounding tissues of the tooth, periodontal ligament, as well as cortical and trabecular bones were modeled. Seven taper posts with two different cross-section geometries (circular and oval shapes) were modeled, as well. Then, the effect of post geometry, post material (carbon fiber and fiberglass), and cement material were investigated by 3D finite element analysis and the stress distribution results were compared.
In all the models, the highest stress levels of the dentin were accumulated at the coronal third of the root, and the highest stress levels at the bonding layers were accumulated at the cervical margin. Narrow circular posts induced the highest stress levels, whereas the stress levels were reduced by using thick oval posts. Application of elastic cement reduces the stress at the bonding layers but increases stress at the dentin.
Finite element analysis showed that prefabricated oval posts are superior to traditional circular ones. The use of cement with low elastic modulus reduces the risk of debonding but raises the risk of root fracture.