整体式 CAD/CAM 二硅酸锂与饰面氧化锆 Y-TZP 冠：疲劳后失效模式和可靠性的比较。

Monolithic CAD/CAM lithium disilicate versus veneered Y-TZP crowns: comparison of failure modes and reliability after fatigue.

机构信息

Department of Bionmaterials and Biomimetics, New York University, New York, NY, USA.

出版信息

Int J Prosthodont. 2010 Sep-Oct;23(5):434-42.

PMID:20859559

Abstract

PURPOSE

The aim of this research was to evaluate the fatigue behavior and reliability of monolithic computer-aided design/computer-assisted manufacture (CAD/CAM) lithium disilicate and hand-layer-veneered zirconia all-ceramic crowns.

MATERIALS AND METHODS

A CAD-based mandibular molar crown preparation, fabricated using rapid prototyping, served as the master die. Fully anatomically shaped monolithic lithium disilicate crowns (IPS e.max CAD, n = 19) and hand-layer-veneered zirconia-based crowns (IPS e.max ZirCAD/Ceram, n = 21) were designed and milled using a CAD/CAM system. Crowns were cemented on aged dentinlike composite dies with resin cement. Crowns were exposed to mouth-motion fatigue by sliding a WC-indenter (r = 3.18 mm) 0.7 mm lingually down the distobuccal cusp using three different step-stress profiles until failure occurred. Failure was designated as a large chip or fracture through the crown. If no failures occurred at high loads (> 900 N), the test method was changed to staircase r ratio fatigue. Stress level probability curves and reliability were calculated.

RESULTS

Hand-layer-veneered zirconia crowns revealed veneer chipping and had a reliability of < 0.01 (0.03 to 0.00, two-sided 90% confidence bounds) for a mission of 100,000 cycles and a 200-N load. None of the fully anatomically shaped CAD/CAM-fabricated monolithic lithium disilicate crowns failed during step-stress mouth-motion fatigue (180,000 cycles, 900 N). CAD/CAM lithium disilicate crowns also survived r ratio fatigue (1,000,000 cycles, 100 to 1,000 N). There appears to be a threshold for damage/bulk fracture for the lithium disilicate ceramic in the range of 1,100 to 1,200 N.

CONCLUSION

Based on present fatigue findings, the application of CAD/CAM lithium disilicate ceramic in a monolithic/fully anatomical configuration resulted in fatigue-resistant crowns, whereas hand-layer-veneered zirconia crowns revealed a high susceptibility to mouth-motion cyclic loading with early veneer failures.

摘要

目的

本研究旨在评估整体式计算机辅助设计/计算机辅助制造（CAD/CAM）锂硅玻璃陶瓷和手工分层涂覆氧化锆全瓷冠的疲劳性能和可靠性。

材料与方法

采用基于 CAD 的下颌磨牙冠预备体，通过快速原型制造作为母模。设计并使用 CAD/CAM 系统加工全解剖式整体式锂硅玻璃陶瓷冠（IPS e.max CAD，n = 19）和手工分层涂覆氧化锆基冠（IPS e.max ZirCAD/Ceram，n = 21）。用树脂水门汀将冠粘接到老化的牙本质样复合材料模具上。通过在颊侧远中嵴上用 WC 压头（r = 3.18 mm）以 0.7 mm 的距离进行口腔运动疲劳试验，使 WC 压头沿颊向滑动，直到发生失效。失效被指定为大块崩瓷或冠体穿透性断裂。如果在高载荷（>900 N）下没有发生失效，则将测试方法更改为阶梯 r 比疲劳。计算了应力水平概率曲线和可靠性。

结果

手工分层涂覆氧化锆冠出现了贴面崩瓷现象，在 100,000 次循环和 200 N 载荷的任务中，可靠性<0.01（双侧 90%置信区间为 0.03 至 0.00）。在口腔运动疲劳的阶梯应力试验中，没有一个全解剖式 CAD/CAM 制造的整体式锂硅玻璃陶瓷冠失效（180,000 次循环，900 N）。CAD/CAM 锂硅玻璃陶瓷冠也能通过 r 比疲劳试验（1,000,000 次循环，100 至 1,000 N）。在 1,100 至 1,200 N 的范围内，锂硅陶瓷似乎存在一个损伤/体断裂的阈值。