Statement of problem

The performance of endocrowns fabricated with different types of computer-aided design and computer-aided manufacturing (CAD-CAM) materials is unclear.

Purpose

The purpose of this finite element analysis (FEA) and in vitro study was to compare and evaluate the stress distribution, failure probability, and fracture resistance of endodontically treated teeth restored with endocrowns from CAD-CAM milling blocks including ceramic, polymer-infiltrated ceramic (PICN), and composite resin.

Material and methods

An endodontically treated first mandibular molar restored with an endocrown was modeled by using a CAD software program and imported into an FEA software program. The model was duplicated and received restorations made from CAD-CAM blocks: Vita Suprinity (VS), IPS e.max CAD (EMX), Vita Enamic (VE), Lava Ultimate (LU), and Grandio blocs (GR). Stress distributions under axial and oblique loading were analyzed. The Weibull function was combined with the FEA results to predict long-term failure probability. The mechanical failure behavior of endocrowns manufactured with these materials was tested by using a universal testing machine. Load-to-failure was recorded, and fractured specimens were subjected to fractography. The data were analyzed by 1-way ANOVA and the post hoc Tukey test (α=.05).

Results

The models of GR and LU exhibited a more even stress distribution. The Weibull analysis revealed that 5 models performed in a similar manner under normal occlusal forces, while LU and VE models achieved the highest probabilities during clenching. The fracture loads of GR (3808 ±607 N) were significantly higher than those of other materials (P<.05). More favorable failure modes were observed in the GR and VE groups. Fractography showed a greater probability of compression curls and arrest lines in the endocrowns of VE, LU, and GR groups.

Conclusions

When restoring endodontically treated teeth, endocrown fabricated with composite resin exhibited a more uniform stress distribution and higher fracture resistance. More evidence from long-term clinical studies is needed to verify this effect.

中文翻译：

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不同 CAD-CAM 材料的牙冠修复体的生物力学行为：3D 有限元和体外分析

问题陈述

用不同类型的计算机辅助设计和计算机辅助制造 (CAD-CAM) 材料制造的内冠的性能尚不清楚。

目的

该有限元分析 (FEA) 和体外研究的目的是比较和评估使用来自 CAD-CAM 铣削块（包括陶瓷、聚合物渗透陶瓷）的牙冠修复的牙髓治疗牙齿的应力分布、失效概率和抗断裂性。 PCN）和复合树脂。

材料与方法

使用 CAD 软件程序对用牙冠修复的经牙髓治疗的第一下颌磨牙进行建模并导入 FEA 软件程序。该模型被复制并接收由 CAD-CAM 块制成的修复体：Vita Suprinity (VS)、IPS e.max CAD (EMX)、Vita Enamic (VE)、Lava Ultimate (LU) 和 Grandio blocs (GR)。分析了轴向和斜向载荷下的应力分布。Weibull 函数与 FEA 结果相结合来预测长期失效概率。使用万能试验机测试了用这些材料制造的内冠的机械失效行为。记录失效载荷，并对断裂的试样进行断口分析。数据通过1向ANOVA和事后Tukey检验（α= .05）进行分析。

结果

GR 和 LU 模型表现出更均匀的应力分布。威布尔分析显示，有5个模型在正常咬合力下以相似的方式执行，而LU和VE模型在紧握过程中的概率最高。GR的断裂载荷（3808±607 N）显着高于其他材料（P <.05）。在 GR 和 VE 组中观察到更有利的失效模式。断口成像显示 VE、LU 和 GR 组的内冠部出现压缩卷曲和停滞线的可能性更大。

结论

在修复经过牙髓治疗的牙齿时，复合树脂制成的牙冠具有更均匀的应力分布和更高的抗断裂性。需要更多来自长期临床研究的证据来验证这种效果。