Element Finite Analysis (FEA) of the resistance to shearing and compression stress of the dental crown executed out of three types of ceramic cemented with three systems adhesive cement

• Main Authors: Otilia Chirca, Cornelia Bîcleşanu, Dan Stoia, Anamaria Florescu, Alexandru Burcea
• Format: Article
• Language: English
• Published: Amaltea Medical Publishing House 2020-12-01
• Series: Romanian Journal of Stomatology
• Subjects: all-ceramic crown; finite element; shearing stress; equivalent stress
• Online Access: https://rjs.com.ro/articles/2020.4/RJS_2020_4_Art-09.pdf

The purpose. The aim of the present study is the Finite Element Analysis (FEA) of a reconstruction model of a molar restored with an entirely ceramic crown, using 3 types of ceramic cemented with 3 different types of adhesive systems in order to identify equivalent stress and shearing values, as well as the deformations in accordance with the direction of the applied stress. Material and method. The geometric model used in FEA is based on one reconstructed from CT scans. Following the CT scan of the dental images and their processing, the structure of an intact molar was made, which was later modified to only select the area of the crown and dental trunk. The FEA analysis aimed to identify both the values of equivalent stress and shear, as well as the deformations of the structure in accordance with the defined materials and the direction of the applied stress. In the present simulation, a single stress value of 170 N was chosen, but applied in sequence at 6 angles: 0°, 30°, 45°, 60°, 75°, 90°. This way the shearing effects are discreetly simulated up to pure compression of the structure. Results and discussions. The stress peaks for both the crown and the cement appear at the level of the horizontal walls, following a sudden decrease of the values recorded on the vertical walls. The change of sign at the level of the shearing stress is normal and is due to the change in orientation of the applied force in relation to the plane in which the stress is studied. Regarding cements, the equivalent stresses indicate that it is possible to reach values that can lead to the appearance of fissures on the dental interface. Conclusions. The values of the mechanical resistances of the 3 ceramics exceed the values of the equivalent and shearing stresses analysed by at least one order of magnitude. Therefore, the application of a similar stress value cannot produce mechanical fractures on any of the ceramics, but fissures can occur in the cement or dentin.