Dong Chen1, Na Wang2, Ya Gao3, Longquan Shao4, Bin Deng5. 1. Lecturer, Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China. 2. Lecturer, Department of Ultrasound, Guangzhou Women and Children's Medical Center, Guangzhou, China. 3. Lecturer, Department of Stomatology, Wuxi No. 2 People's Hospital, Wuxi, China. 4. Professor, Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China. Electronic address: shaolongquan@smu.edu.cn. 5. Professor, Department of Stomatology, People's Liberation Army General Hospital, Beijing, China.
Abstract
STATEMENT OF PROBLEM: Zirconia posts exhibit high strength and toughness, but reliable bonding with the resin core is difficult to attain. The use of a ferrule has been found to improve stress distribution in the root of endodontically treated teeth. PURPOSE: The purpose of this finite element analysis study was to measure the stress distribution in the post-core system and root structure of a maxillary canine. MATERIAL AND METHODS: A right maxillary canine was embedded and subjected to a micro-computed tomography scan. Three-dimensional dynamic scan data were then transformed, and a finite element model of 4 dentin ferrule heights was designed with zirconia posts and heat-pressed glass ceramics for a complete crown restoration. Von Mises stresses were determined by applying a 300 N static load to the middle of the lingual surface of the crown. RESULTS: When the ferrule height increased from 0 to 3 mm, the maximum von Mises stress of the zirconia post decreased from 196 to 149 MPa, and that on the zirconia post-dentin interface decreased from 174 to 132 MPa. The maximum von Mises stress decreased from 39.8 to 32.5 MPa in the apical root and from 59.5 to 49.9 MPa in the mid-root when the ferrule height increased from 0 to 3 mm. CONCLUSIONS: Increased ferrule height is associated with reduced von Mises stress in the zirconia post and the post-dentin interface, with an apparent shift of von Mises stress to the root cervical area from the mid-root and the apex.
STATEMENT OF PROBLEM: Zirconia posts exhibit high strength and toughness, but reliable bonding with the resin core is difficult to attain. The use of a ferrule has been found to improve stress distribution in the root of endodontically treated teeth. PURPOSE: The purpose of this finite element analysis study was to measure the stress distribution in the post-core system and root structure of a maxillary canine. MATERIAL AND METHODS: A right maxillary canine was embedded and subjected to a micro-computed tomography scan. Three-dimensional dynamic scan data were then transformed, and a finite element model of 4 dentin ferrule heights was designed with zirconia posts and heat-pressed glass ceramics for a complete crown restoration. Von Mises stresses were determined by applying a 300 N static load to the middle of the lingual surface of the crown. RESULTS: When the ferrule height increased from 0 to 3 mm, the maximum von Mises stress of the zirconia post decreased from 196 to 149 MPa, and that on the zirconia post-dentin interface decreased from 174 to 132 MPa. The maximum von Mises stress decreased from 39.8 to 32.5 MPa in the apical root and from 59.5 to 49.9 MPa in the mid-root when the ferrule height increased from 0 to 3 mm. CONCLUSIONS: Increased ferrule height is associated with reduced von Mises stress in the zirconia post and the post-dentin interface, with an apparent shift of von Mises stress to the root cervical area from the mid-root and the apex.