The effect of margin design on stress distribution in zirconia-based full crown restorations: A 3D finite element analysis

Purpose: The aim of this study is to evaluate the effect of changes in margin design on the stress distribution on the restoration in zirconia-based full-crown restorations using 3D finite element analysis. Material and Methods: To be used in the design of full-crown restorations, tooth number 16 was prepared in chamfer step type on a maxillary tooth-jaw model (AG-3: Tipodont, frasaco, Germany). The prepared tooth was scanned using a desktop scanner, and a 3D finite element analysis model was obtained. Zirconia frameworks are divided into 3 groups according to margin design: uniform thickness hood type (Model A), ¾ partial crown form (Model B), and lingual banded (Model C). The crown form was completed by using felspathic porcelain as the superstructure material. In order to examine the stress distributions of the margin design on the restoration, the maximum principal stress (MPa) values under 600 N vertical load were investigated. Result: The maximum stress on the zirconia framework was observed in Model A (82.90 MPa), and the maximum stress on the tooth was observed in Model B (49.34 MPa). The maximum stress on the feldspathic porcelain has the highest value in Model A (21,860 MPa). The minimum stress on the tooth occurred in Model B and is 13.33 MPa. In the zirconia framework, the lowest stress is 11.54 MPa in Model B. Conclusions: Within the results of the study, it is clear that the framework design affects the force generated on the restoration and transmitted to the tooth. The results of the study will benefit dentists in determining the infrastructure design in zirconia-based restorations. Lingual band designs have been found successful.