Statement of problem

Additive manufacturing has been proposed for the fabrication of occlusal devices. However, information about the mechanical properties of additively manufactured devices is lacking.

Purpose

The purpose of this in vitro study was to evaluate the influence of the postpolymerization unit and artificial aging on the Martens hardness (HM) and indentation modulus (E_IT) of different 3D-printed materials in comparison with a conventionally milled material.

Material and methods

Thirty disks (20 mm in diameter and 5 mm in thickness) were additively manufactured (D20 II, Rapidshape & Form 2) for each 3D-printed material (NextDent Splint, Formlabs Dental LT Clear, and Freeprint Splint). As a control, 10 disks of the same thickness were cut from a conventionally milled material (Temp Premium). Each specimen was measured for HM and E_IT (ZHU 0,2) after fabrication. The specimens were stored in water at 37 °C and measured again after 2 and 4 weeks. The data were analyzed statistically by using the Kruskal-Wallis, Mann-Whitney U, and Wilcoxon tests (adjusted by Bonferroni correction α=.05/27=.002).

Results

The highest influence on HM parameters was shown by artificial aging (partial eta squared: HM: η_P²=0.840, E_IT: η_P²=0.855, P<.001), followed by the material (HM: η_P²=0.690 E_IT: η_P²=0.845, P<.001) and the postpolymerization unit (HM: η_P²=0.649, E_IT: η_P²=0.778, P<.001). Initial HM values ranged from 147 ±8.11 N/mm² for Formlabs postpolymerized in Otoflash to 89.5 ±8.55 N/mm² for Detax postpolymerized in the Labolight unit. E_IT values ranged from 3.92 ±0.061 kN/mm² for Formlabs postpolymerized in Otoflash to 2.48 ±0.212 kN/mm² for Detax postpolymerized in the Labolight unit. In general, HM and E_IT values decreased after water storage, whereas the values remained unchanged for the control group.

Conclusions

HM parameters of additively manufactured occlusal devices depend on postpolymerization strategy. Otoflash and Printbox result in higher HM and E_IT values. The 3D-printed materials are more prone to artificial aging than the control group, which brings into question their long-term service.

中文翻译：

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后聚合和老化对3D打印咬合装置Martens参数影响的体外研究

问题陈述

已经提出了增材制造用于咬合装置的制造。但是，缺乏有关增材制造装置的机械性能的信息。

目的

这项体外研究的目的是评估与传统碾磨后的材料相比，后聚合单元和人工时效对不同3D打印材料的马氏硬度（HM）和压痕模量（E _IT）的影响。

材料与方法

对于每种3D打印材料（NextDent夹板，Formlabs Dental LT Clear和Freeprint夹板），分别制造了三十张圆盘（直径20毫米，厚度5毫米）（D20 II，Rapidshape＆Form 2）。作为对照，从常规研磨的材料（Temp Premium）上切下10个相同厚度的圆盘。在制造后测量每个样品的HM和E _IT（ZHU 0,2）。将标本存储在37°C的水中，并在2周和4周后再次测量。使用Kruskal-Wallis，Mann-Whitney U和Wilcoxon检验（通过Bonferroni校正α= .05 / 27 = .002进行调整）对数据进行统计分析。

结果

上HM参数最高影响通过人工时效所示（部分Eta平方：HM：η _P ² = 0.840，E _IT：η _P ² = 0.855，P <0.001），随后通过将材料（HM：η _P ² = 0.690Ë _IT：η _P ² = 0.845，P <0.001）和后聚合单元（HM：η _P ² = 0.649，E _IT：η _P ² = 0.778，P <0.001）。对于在Otoflash中后聚合的Formlabs，初始HM值范围为147±8.11 N / mm ²至89.5±8.55 N / mm ²用于在Labolight单元中进行后聚合的Detax。E _IT值范围从在Otoflash中后聚合的Formlabs的3.92±0.061 kN / mm ^2到在Labolight单元中后聚合的Detax的2.48±0.212 kN / mm ²。通常，蓄水后HM和E _IT值降低，而对照组则保持不变。

结论

增材制造的咬合装置的HM参数取决于后聚合策略。Otoflash和Printbox带来更高的HM和E _IT值。3D打印的材料比对照组更容易发生人工老化，这给它们的长期使用带来了疑问。