Lebanese University, Faculty of Dental Medicine, Department of Prosthodontics, Beirut, Lebanon.
University of Zurich, Center for Dental and Oral Medicine, Division of Dental Biomaterials, Zurich, Switzerland.
J Esthet Restor Dent. 2019 Jul;31(4):378-387. doi: 10.1111/jerd.12486. Epub 2019 May 8.
The purpose of this in vitro study was to evaluate the fracture resistance and failure modes of endocrowns made of three computer-aided design/computer-aided manufacturing (CAD/CAM) materials subjected to thermo-mechanical cycling loading.
Eighty mandibular molars were divided into four groups (n = 20): one (C E) was restored with lithium disilicate glass-ceramic conventional crowns, three were restored with endocrowns made of three different CAD/CAM materials; (E E) lithium disilicate glass-ceramic, (E V) zirconia-reinforced lithium silicate glass-ceramic, and (E C) resin nano-ceramic. After cycling loading, half of the samples from each group were loaded axially and the other half was loaded laterally. Fracture resistance was recorded in Newton (N) and failure modes were classified. Two-way ANOVA, Bonferroni post hoc (α = .05), Chi-square, and multiple logistic regression tests were used to analyze data.
Statistically significant interaction were recorded between fracture resistance (N) and loading (P < .001), and groups (conventuional crown and endocrowns; P < .001). Endocrowns presented higher fracture strength than conventional crowns. Fracture resistance was significantly larger under axial loading. The numbers of irreparable failures were extremely important in the endocrowns groups (Groups E E, E V, E C), and only conventional crowns (Group C E) showed almost no irreparable failures under axial loading.
Lithium disilicate glass-ceramic recorded the highest fracture resistance under axial and lateral loading.
The number of irreparable failures with all endocrown materials tested do not suggest yet the use of this type of restorations in posterior teeth.
本体外研究的目的是评估三种计算机辅助设计/计算机辅助制造（CAD/CAM）材料制成的嵌体的抗断裂能力和失效模式，这些嵌体在热机械循环加载下。
将 80 颗下颌磨牙分为四组（n=20）：一组（C E）用锂硅玻璃陶瓷常规冠修复，三组用三种不同 CAD/CAM 材料制成的嵌体修复；（E E）锂硅玻璃陶瓷、（E V）氧化锆增强硅酸锂玻璃陶瓷和（E C）树脂纳米陶瓷。循环加载后，每组一半样本进行轴向加载，另一半进行侧向加载。以牛顿（N）记录断裂阻力，并对失效模式进行分类。采用双向方差分析、Bonferroni 事后检验（α=0.05）、卡方检验和多因素逻辑回归检验对数据进行分析。
记录到断裂阻力（N）和加载（P<0.001）以及组之间（常规冠和嵌体；P<0.001）之间存在统计学显著的相互作用。嵌体的断裂强度高于常规冠。轴向加载时断裂阻力显著增大。在嵌体组（E E、E V 和 E C 组）中，无法修复的失效数量非常重要，而仅常规冠（C E 组）在轴向加载下几乎没有无法修复的失效。
锂硅玻璃陶瓷在轴向和侧向加载下记录到最高的断裂阻力。
所有测试的嵌体材料的无法修复的失效数量尚不能表明在后牙中使用这种类型的修复体。
