Statement of problem

Zirconia restorations can be processed by using stereolithography additive manufacturing (AM) technologies. However, whether additive manufactured zirconia could achieve flexural strength values comparable with those of milled zirconia is unclear.

Purpose

The purpose of this in vitro study was to compare the flexural strength and Weibull characteristics of milled and additive manufactured zirconia.

Material and methods

A total of 40 zirconia bars (25×4×1.2 mm) were obtained by using 2 manufacturing procedures, subtractive (CNC group) (IPS e.max ZirCAD; Ivoclar Vivadent AG) and additive manufacturing (AM group) (3DMix ZrO₂; 3DCeram) technologies and assigned to 2 subgroups according to accelerating artificial aging procedures (mastication simulation): nonaged and aged (n=10). Flexural strength was measured in all specimens by using 3-point bend tests according to ISO/CD 6872.2 with a universal testing machine (Instron Model 8501; Instron Corp). Two-parameter Weibull distribution values, including the Weibull modulus, scale (m), and shape (0) were calculated. Flexural strength values were analyzed by using 2-way ANOVA and Student t statistical tests (α=.05).

Results

The manufacturing procedure (P<.001), the mastication simulating aging procedure (P<.001), and the interaction between them (P<.001) significantly affected flexural strength values. The CNC group exhibited statistically higher flexural strength values than those in the AM group when the specimens were tested before performing an aging procedure (P<.001) and after mastication simulation (P<.001). Moreover, mastication simulation produced a significant reduction in flexural strength for both the CNC group (P<.039) and the AM group (P<.001).

Conclusions

The manufacturing process reported a significant effect on the flexural strength of the zirconia material tested. Mastication simulation as a means of accelerating artificial aging resulted in the significantly decreased flexural strength values of milled and additively manufactured zirconia material, with the Weibull moduli being significantly higher for the milled groups versus the milled specimens.

中文翻译：

---

与研磨的氧化锆相比，制造的立体光刻添加剂的抗弯强度和威布尔特性

问题陈述

氧化锆修复体可通过使用立体光刻增材制造（AM）技术进行处理。但是，用添加剂制造的氧化锆能否达到与碾磨的氧化锆相当的抗弯强度值尚不清楚。

目的

这项体外研究的目的是比较研磨和添加的氧化锆的弯曲强度和威布尔特性。

材料与方法

通过减法（CNC组）（IPS e.max ZirCAD； Ivoclar Vivadent AG）和增材制造（AM组）（3DMix ZrO ₂；2个制造程序）共获得40条氧化锆棒（25×4×1.2 mm）。 3DCeram）技术，并根据加速的人工老化程序（塑化模拟）分为2个子组：未老化和老化（n = 10）。通过使用通用测试仪（Instron型号8501； Instron Corp）根据ISO / CD 6872.2进行三点弯曲测试，测量所有样品的抗弯强度。计算了两参数的威布尔分布值，包括威布尔模量，比例（m）和形状（0）。弯曲强度值通过使用2通方差分析和Student t统计检验进行分析（α= .05）。

结果

制造过程（P <.001），模拟咀嚼老化过程（P <.001）以及它们之间的相互作用（P <.001）显着影响抗弯强度值。当在老化过程之前（P <.001）和咀嚼模拟后（P <.001）对样品进行测试时，CNC组显示出比AM组更高的统计抗弯强度值。此外，咀嚼模拟使CNC组（P <.039）和AM组（P <.001）的弯曲强度均显着降低。

结论

制造过程报告了对测试的氧化锆材料的弯曲强度有显着影响。作为加速人工老化的一种方法，通过模拟咀嚼法，可以显着降低碾磨过的和添加制造的氧化锆材料的抗弯强度值，与碾磨过的试样相比，碾磨过的组的Weibull模量明显更高。