Numerical investigation of the stress-strain state of zirconium dioxide pin structures manufactured using CAD CAM technologies

Abstract

Numerical studies were carried out to determine the stress-strain state of pin stump structures made of zirconium dioxide. The calculation models were part of the dentoalveolar segment in the form of a cylinder, composed of a single-rooted tooth, dentin, periodontal ligament, compact bone of the alveolus, gums, spongy bone and a monolithic structure consisting of a crown fixed on a stump insert and a rod-pin. Three cases of such pin design models were considered. A numerical study was carried out for three different thicknesses of the rod, which were modeled as follows: the volume of the 2nd and 3rd pins doubled compared to the previous one – case 1 (thin rod), case 2(medium) and case 3 (thick). The finite element method was used to study the field of displacements and stresses according to von Mises both in the structures themselves and in the tissues surrounding them. Two cases of the load on the chewing surface of the tooth crown were established for comparative analysis in all cases: a distributed vertical load of 100 N and the same load at an angle of 45°. As a result of numerical studies, pin structures case 2 and 3 showed an ad-vantage over the design with a thin rod (case 1) both in terms of displacements and stresses. Case2 (average rod thickness) is recommended for use in practice. Structures of this type can be used to restore the crown part of the tooth in case of its complete absence or significant destruction, as well as a support for a bridge prosthesis.