Effects of a modified margin design, material, and loading type on the stress distribution of endocrowns: A 3D finite element analysis

In this innovative study, the ferrule design for endocrowns was compared with a new preparation design with tetra-corner retention grooves at each corner of the access cavity, and the 3D finite element method was used for analysis. Resin nanoceramic (RNC), lithium disilicate glass-ceramic (LDS), polyetheretherketone (PEEK), and polymer-infiltrated ceramic network (PICN) materials were investigated. The new design significantly reduced the stress for LDS and PICN in axial and oblique loadings. On remaining tooth tissues, the tetra-corner retention groove design increased the stress peak for RNC and PEEK compared to the ferrule, while it decreased the stress for LDS and PICN under both forces. It was concluded that the new, modified preparation design could be used as an alternative design to the ferrule.