Photoelastic stress analysis of different post and core restoration methods

Abstract

The aim of this study was to compare three types of post and core systems by analyzing the stress magnitude within the root. To this end, two-dimensional photoelastic simulation models of endodontically treated maxillary central incisors were fabricated. Three different types of post and core systems were selected for this study: composite resin post and core, composite resin core in combination with a glass fiber post, and conventional cast metal post and core. The fabricated models were observed in a transmission polariscope with the same loading force (400 N) on 45° palatal direction and the fringe orders registered were thereby analyzed. Results obtained in this study suggested that abutment build-up using composite resin core in combination with a glass fiber post model produced the lowest stress concentration and is hence effective in preventing stress concentration in the case of restored endodontically treated teeth.

Photoelastic stress analysis of endodontically treated teeth restored with different post systems: normal and alveolar bone resorption cases

“…Still, there remained a considerable difference in the periodontal ligament function. Given the material constraints, the periodontal ligament was not included in the simulation models in the present study 19) . However, the presence of the periodontal ligament could account for the difference in experimental results 43) .…”

“…In other studies of both static and dynamic loading tests, the comparative results of the root fracture between the teeth restored with fiber posts and metallic posts were consistent 34) . Hence, instead of the dynamic force, a simple but effective static force was used in the photoelastic analysis of the present study 19) . The magnitude of the force applied in this study was 150 N to assume the maximum occlusal force of the incisor and enable easy observation without damaging the models.…”

“…Around the upper part of the completed post models, an epoxy resin material in liquid state was poured and formed into the predetermined shape of the composite resin core. The epoxy resin material was synthesized using mixing a base resin (JER828, Japan Epoxy Resin Ltd., Tokyo, Japan), a hardener (Diethylene triamine, Wako Pure Chemical Industries, Ltd., Tokyo, Japan) and a softener (Thiokol LP-3, Toray Fine Chemical Ltd., Tokyo, Japan) at a ratio of 100:10:1 19) . Composite resin adhesion was simulated using the epoxy resin material mentioned above.…”

Photoelastic stress analysis of different prefabricated post-and-core materials

“…In some situations it is better for the photoelastic model to resemble the shape of an actual tooth 37) . However, in this experiment, the modulus of elasticity of the photoelastic sheet is similar to that of human dentin, and fringe values developed from the stresses were well demonstrated around the post, which was the primary objective of the study.…”

“…This method has the advantage of applying a given stress state to an actual model and using the fringe value of the material to evaluate the stress distribution within the model. Virtual models have also been developed with finite element analysis (FEA) to measure stresses induced by posts 37) . FEA has proven valuable in health sciences research.…”