Investigation of Stress Distribution And Fatique Performance in Restored Teeth Using Different Thickness of Adhesive Materials and Different Restorative Materials:3D Finite Element Analysis (FEM)

Background: The aim of this study was to compare the stress distributions and fracture life of dental tissues and restorative materials restored using different thicknesses of adhesive materials and different restorative materials. Methos : A tooth number 36 without caries and loss of material was scanned using a CBCT device. The files obtained were transferred to Mimics software. Using this software, enamel tissue, dentin tissue and pulp regions were extracted separately in STL format. STL files were transferred to Geomagic Design X software for surface correction and saved in STP format. The obtained STP files were transferred to the Solidworks programme and 4 different (DO, MO, MOD, O) cavity preparations were made on the models. Each of these cavities was restored with bulk-fill composite, conventional composite and hybrid composite in the computerised environment. A layer of adhesive material with a thickness of 10, 15 and 20 micrometres was applied under all materials and stress distributions and fracture lifetimes were analysed by 3D finite element stress analysis method. Results: When we evaluated the models with different thicknesses of adhesive material, the stress values on enamel, dentin and adhesive material were highest in the models with bulk-fill composite, while the stress values on the restoration were highest in the models with hybrid composite. As the thickness of the adhesive material decreased, the stress values accumulated on the material increased. In addition, the models in which the enamel tissue started to fracture the earliest were the models restored with bulk-fill composite. The models in which the restorative materials started to fracture the earliest were the models restored with hybrid composites, while the models in which the restorative materials started to fracture the latest were the models restored with bulk-fill composites. Conclusion: When materials with low young's modulus are used for restorative purposes, they cause too much stress accumulation on enamel and dentin tissues. Accordingly, these tissues start to fracture early. When materials with large Young's modulus are used, too much stress is applied to the restoration and the restoration fractures prematurely.