Statement of problem

Materials have been developed to reduce the chipping of ceramic veneer and improve the esthetics of anterior ceramic veneered restorations. However, studies of the effects of material and substructure design on fracture resistance are sparse.

Purpose

The purpose of this in vitro study was to investigate the fracture resistance of metal-ceramic (MC), zirconia-feldspathic porcelain (ZC), and zirconia-lithium disilicate (ZL) anterior restorations and evaluate the effect of material and substructure design.

Material and methods

After preparing and scanning artificial maxillary central incisor teeth, titanium abutments and restoration specimens (n=90) were fabricated. MC, ZC, and ZL materials were prepared with substructure designs A (two-third coverage of the palatal surface) and B (one-third coverage of the palatal surface). After cementation, the specimens were thermocycled (10 000 cycles, 5 and 55 °C). Fracture load measurements, failure mode analysis, energy dispersive X-ray spectroscopy (EDS), line scan analysis, fractography, finite element analysis (FEA), and Weibull analysis were performed. Two-way ANOVA was used to identify the effects of material and substructure design on fracture load. One-way ANOVA was used to identify significant differences of fracture load (α=.05).

Results

MC and ZL showed significantly higher fracture load than ZC (P<.05). MC_A showed a significantly higher fracture load than MC_B (P<.05). ZC_A exhibited the lowest Weibull modulus. FEA revealed that the maximum principal stress occurred near the loading area of the veneer. ZL displayed the lowest maximum principal stress among all the materials.

Conclusions

ZL and MC_A exhibited more favorable fracture resistance. The substructure design of MC, with increased metal coverage of the palatal surface, improved fracture resistance significantly.

中文翻译：

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不同陶瓷材料和亚结构设计对前牙修复体抗折性的影响

问题陈述

已经开发出一些材料来减少陶瓷贴面的碎裂并改善前部陶瓷贴面修复体的美观性。然而，关于材料和子结构设计对抗断裂性影响的研究很少。

目的

这项体外研究的目的是研究金属陶瓷 (MC)、氧化锆长石瓷 (ZC) 和氧化锆-二硅酸锂 (ZL) 前牙修复体的抗断裂性，并评估材料和下部结构设计的效果。

材料与方法

在制备和扫描人造上颌中切牙后，制作钛基台和修复体标本（n=90）。MC、ZC 和 ZL 材料采用子结构设计 A（腭表面覆盖率的三分之二）和 B（腭表面覆盖率的三分之一）制备。胶结后，对试样进行热循环（10 000 次循环，5 和 55 °C）。进行了断裂载荷测量、失效模式分析、能量色散 X 射线光谱 (EDS)、线扫描分析、断口分析、有限元分析 (FEA) 和 Weibull 分析。双向方差分析用于确定材料和子结构设计对断裂载荷的影响。单因素方差分析用于识别断裂载荷的显着差异（α=.05）。

结果

MC 和 ZL 的断裂载荷显着高于 ZC ( P <.05)。MC_A 的断裂载荷显着高于 MC_B ( P <.05)。ZC_A 表现出最低的威布尔模量。有限元分析表明，最大主应力发生在单板的加载区域附近。ZL 在所有材料中显示出最低的最大主应力。

结论

ZL和MC_A表现出更好的抗断裂性。MC的子结构设计，增加了腭表面的金属覆盖率，显着提高了抗断裂性。