Department of Prosthondontics, The Affiliated Stomatology Hospital, Chongqing Medical University, Chongqing, China.
Dent Traumatol. 2010 Feb;26(1):64-9. doi: 10.1111/j.1600-9657.2009.00829.x. Epub 2009 Oct 14.
Teeth that have been endodontically treated and restored with postcore crown may experience fracture sometimes. Some researchers have analyzed the stress of the anterior teeth after postcore crown restoration, but the stress of the posterior teeth after such restoration has not been reported. We used three-dimension finite element methods to analyze the stress magnitude and distribution of remaining dentin in posterior tooth residual root restored with postcore crown. The binding material, loading direction, number, length and material of posts were studied.
The models of residual root of maxillary first molar restored with postcore crown were created by CT scanning, mimics software and abaqus software. Different number, length and material of posts were used in the modeling. The posts were cemented with zinc-phosphate cement or composited resin. A load of 240 N was applied to the occlusal surface in four directions and tensile, shear, and von Mises stresses were calculated.
(i) The maximum stress on remaining dentin changed irregularly as the number and length of posts changed. (ii) The maximum stress on remaining dentin decreased slightly as elastic modulus of the material of posts increased. (iii) The maximum stress on bonding layer and remaining dentin was lower when bonded with resin luting agent than with zinc-phosphate cement. (iv) The maximum stress on remaining dentin increased markedly as loading angle increased.
The number, length, material of posts, bonding material and loading angle all have influence on the magnitude and distribution of stress. The influence of loading angle is most apparent.
经过根管治疗并使用桩核冠修复的牙齿有时可能会发生断裂。一些研究人员分析了桩核冠修复后前牙的应力情况，但尚未报道这种修复后后牙的应力情况。我们使用三维有限元方法分析了桩核冠修复后的后牙残根剩余牙本质的应力大小和分布。研究了粘结材料、加载方向、桩的数量、长度和材料。
通过 CT 扫描、mimics 软件和 abaqus 软件创建了上颌第一磨牙残根桩核冠修复模型。在建模中使用了不同数量、长度和材料的桩。将桩用磷酸锌水门汀或复合树脂粘结。在四个方向的牙合面施加 240 N 的载荷，计算拉伸、剪切和 von Mises 应力。
（i）随着桩的数量和长度的变化，剩余牙本质上的最大应力不规则变化。（ii）随着桩材料弹性模量的增加，剩余牙本质上的最大应力略有下降。（iii）与磷酸锌水门汀相比，用树脂粘结剂粘结时，粘结层和剩余牙本质上的最大应力较低。（iv）随着加载角度的增加，剩余牙本质上的最大应力显著增加。
桩的数量、长度、材料、粘结材料和加载角度都对应力的大小和分布有影响。加载角度的影响最为明显。
