Chen Dong, Wang Na, Gao Ya, Shao Longquan, Deng Bin
Lecturer, Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
Lecturer, Department of Ultrasound, Guangzhou Women and Children's Medical Center, Guangzhou, China.
J Prosthet Dent. 2014 Dec;112(6):1406-15. doi: 10.1016/j.prosdent.2014.05.017. Epub 2014 Jul 1.
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.
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.
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.
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.
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.
氧化锆桩具有高强度和韧性，但难以与树脂核实现可靠粘结。已发现使用箍可以改善根管治疗后牙齿根部的应力分布。
本有限元分析研究的目的是测量上颌尖牙桩核系统和牙根结构中的应力分布。
将一颗右上颌尖牙嵌入并进行微计算机断层扫描。然后对三维动态扫描数据进行转换，并设计了4种牙本质箍高度的有限元模型，使用氧化锆桩和热压玻璃陶瓷进行全冠修复。通过在牙冠舌面中部施加300 N静载荷来确定冯·米塞斯应力。
当箍高度从0增加到3 mm时，氧化锆桩的最大冯·米塞斯应力从196 MPa降至149 MPa，氧化锆桩与牙本质界面处的最大冯·米塞斯应力从174 MPa降至132 MPa。当箍高度从0增加到3 mm时，根尖部的最大冯·米塞斯应力从39.8 MPa降至32.5 MPa，根中部的最大冯·米塞斯应力从59.5 MPa降至49.9 MPa。
箍高度增加与氧化锆桩及桩-牙本质界面处冯·米塞斯应力降低相关，且冯·米塞斯应力明显从中部和根尖向颈部区域转移。
