Stomatology Health Care Center, Affiliated Shenzhen Maternity & Child Healthcare Hospital, Southern Medical University, Shenzhen, China.
Nanfang Hospital, Southern Medical University, Guangzhou, China.
BMC Oral Health. 2021 Oct 5;21(1):495. doi: 10.1186/s12903-021-01865-w.
This study aimed to evaluate the influence of different types of restorative materials and resin cements on the stress distribution in the regions of the restoration, cement layer and dental remnant in endodontically treated posterior endocrowns.
A 3D finite element analysis (FEA) model of the first mandibular molar that was restored with an endocrown designed by computer-aided design (CAD) software was generated. Three kinds of restorative materials (Vita Enamic (VE), IPS e.max CAD (EMX) and Grandio blocs (GR)) and two types of cementing materials (NX3 and Maxcem Elite Chroma (MX)) were analysed with such a model. The food layer was also designed before vertical (600 N) forces were applied to simulate physiological masticatory conditions. Thermal expansion was used to simulate the polymerization shrinkage effects of cement layers. The results were obtained by colorimetric graphs of the maximum principal stress in the restoration and tooth remnant. The failure risk of the cement layer was also calculated based on the normal stress.
The elastic modulus was positively correlated with the tensile stress peak values in the restoration, mainly at the intaglio surface. However, in the cervical enamel and cement layer, restorative material with a higher elastic modulus generated lower peak stress values. The cement with a higher elastic modulus resulted in higher stress peak values inside the cement layer. The combination of EMX (restorative material) and NX3 (cement material) in the cement layer resulted in the lowest failure risk.
The ceramic material EMX with a higher elastic modulus appeared to be more effective at protecting the cement layer and residual enamel tissue. Based on the analysis of the failure risk of the cement layer, the combination of EMX and NX3 was recommended as an optional material for endocrowns for endodontically treated posterior teeth.
本研究旨在评估不同类型的修复材料和树脂水门汀对根管治疗后端核冠修复体、粘结层和牙体剩余部分区域的应力分布的影响。
通过计算机辅助设计（CAD）软件设计的下颌第一磨牙的三维有限元分析（FEA）模型，分析三种修复材料（ Vita Enamic（VE）、IPS e.max CAD（EMX）和 Grandio blocs（GR））和两种粘结材料（NX3 和 Maxcem Elite Chroma（MX））。在模拟生理咀嚼条件下，还设计了垂直（600N）力作用下的食物层。热膨胀用于模拟粘结层的聚合收缩效应。结果通过修复体和牙体剩余部分的最大主应力的彩色图获得。还根据法向应力计算粘结层的失效风险。
弹性模量与修复体的拉伸应力峰值呈正相关，主要在凹面。然而，在颈釉质和粘结层，弹性模量较高的修复材料产生的峰值应力值较低。弹性模量较高的粘结剂会导致粘结层内产生更高的峰值应力。粘结层中 EMX（修复材料）和 NX3（粘结材料）的组合导致的失效风险最低。
弹性模量较高的陶瓷材料 EMX 似乎更能有效保护粘结层和剩余牙釉质组织。基于粘结层失效风险的分析，推荐 EMX 和 NX3 的组合作为后牙根管治疗后端核冠的可选材料。
