动态载荷下三种形式箍效应的有限元分析

目的 在模拟口腔动态载荷下,研究上颌中切牙烤瓷核桩冠修复中三种形式箍效应的应力分布特点,通过动静态载荷下应力分析,为优化桩冠设计提供实验数据.方法 建立上颌中切牙烤瓷核桩冠三维有限元模型.模拟临床箍效应的3种形式(A、全冠边缘直接包绕牙体;B、桩核颈环直接包绕牙体;C、冠包绕1 mm,核包绕1 mm),通过动态加载分析牙本质受力情况并与静态加载结果相比较.结果 在动态载荷下,三组实验牙本质应力均表现为从颈部向根中部、根尖部逐渐增高;与静态载荷相比较,高应力区范围从根中部扩大至桩末端根尖区牙本质,在桩末端处应力值最高.动态载荷时根中下段唇侧牙体受力显著变大.各实验组每一分步动态加载时的高应力区位置恒定,不随加载量及应力值变化而变化.在应力峰值上,σvonA＜σvonC,σvonB＜σvonC,(p＜0.05).反转斜面降低应力峰值的作用最小.结论 通过计算机输入和手工划分网格相结合,可以建立符合临床和实验要求的动态有限元分析模型.在箍高度为2 mm时,动态载荷环境下冠包绕牙体(A)与核颈环(B)形式的箍效应均优于反转斜面形式(C),而A、B组则无显著差别.高弹性模量桩易导致桩末端和唇侧牙体受力过大而出现修复失败.

Dynamic finite element analysis of three ferrule designs in post crown under impact loading

OBJECTIVE: To investigate the stress distribution in three ferrule designs in a maxillary central incisor restoration using PFM crown with post, and evaluate the biomechanical mechanism of the ferrule effect in the post crown by 3D finite element dynamic analysis. METHODS: The 3D finite element model of a maxillary central incisor restored with post and PFM crown was established. By simulating three types of ferrule effect crown wrapping dentine (A), core collar wrapping (B), and contrabevel (C)] under dynamic loading, the dentin stress was analyzed. RESULTS: During dynamic loading, the stress distribution tended to increase from the cervical part to root middle and radical part of the tooth, and greater high stress area was found around the apex of the post, where the peak stress was observed value. The stress of the labial dentin of the root inferior segment increased obviously. The high stress areas were invariable at every loading step during dynamic loading. The peak stress was sigma(vonA)