Effect of finish line design on stress distribution in bilayer and monolithic zirconia crowns: a three‐dimensional finite element analysis study

Abstract

This study evaluated the influence of different finish line designs and abutment materials on the stress distribution of bilayer and monolithic zirconia crowns using three-dimensional finite element analysis (FEA). Three-dimensional models of two types of zirconia premolars - a yttria-stabilized zirconia framework with veneering ceramic and a monolithic zirconia ceramic - were used in the analysis. Cylindrical models with the finish line design of the crown abutments were prepared with three types of margin curvature radius (CR): CR = 0 (CR0; shoulder margin), CR = 0.5 (CR0.5; rounded shoulder margin), and CR = 1.0 (CR1.0; deep chamfer margin). Two abutment materials (dentin and brass) were analyzed. In the FEA model, 1 N was loaded perpendicular to the occlusal surface at the center of the crown, and linear static analysis was performed. For all crowns, stress was localized to the occlusal loading area as well as to the axial walls of the proximal region. The lowest maximum principal stress values were observed when the dentin abutment with CR0.5 was used under a monolithic zirconia crown. These results suggest that the rounded shoulder margin and deep chamfer margin, in combination with a monolithic zirconia crown, potentially have optimal geometry to minimize occlusal stress.

Effect of margin design on fracture load of zirconia crowns

“…The finding that the chamfer design crowns fractured at a higher load than did the slice design crowns in both production‐method groups indicates that the commonly recommended chamfer margin design gives the strongest crowns. This is in accordance with previous studies . The increased thickness in the crown margin probably explains this result.…”

“…Previous studies reveal that alterations in margins design affect the cervical stress distribution . The lowest load at fracture was 1,202 N, which is higher than the maximally measured biting force of 800–1,000 N .…”

Influence of preparation design on fracture resistance of different monolithic zirconia crowns: A comparative study

“…We found that monolithic traditional zirconia with shoulder margin design has higher fracture load than monolithic traditional zirconia with feather-edge margin design in both groups. It might be because the stress distribution pattern in the shoulder margin design as the circumferential shoulder withstands occlusal forces and results in less concentration of stress on axial walls 2627. Furthermore, an increase in the crown margin and axial wall thickness lead to fracture at a higher load.…”

Farkli Kenar Bi̇ti̇m Ve Alt Yapi Di̇zaynlarinin Çeşi̇tli̇ Zi̇rkonyum Alt Yapilar Üzeri̇ndeki̇ Vener Porseleni̇n Kirilma Di̇renci̇ne Etki̇si̇ni̇n İncelenmesi̇

“…Miura ve ark. 23 shoulder, rounded shoulder ve derin chamfer basamak tiplerini Sonlu Elemanlar Stres Analiz yöntemi ile karşılaştırmışlar, derin chamfer ve rounded shoulder basamak tipinin zirkonyum restorasyonların mekanik performanslarını geliştirdiğini gözlemlemişlerdir. Malament ve Socransky 24 shoulder ve chamfer basamak şekillerinin tam seramiklerde vener porselenlerin kırılma riski açısından önemli bir fark oluşturmadığını belirtmişlerdir.…”