龈下残根桩核冠修复的三维有限元模型建立

Establishment of the three-dimensional finite element model of the post crown with subgingival post-core for the maxillary central incisor

目的:建立不同程度缺损至牙龈下与牙槽骨内上颌中切牙残根通过龈下桩修复的桩核冠三维有限元模型,分析龈下桩修复方法的可行性。方法:使用Micro CT扫描上颌离体中切牙获得CT断层图片,通过Minics、Geomagic和UG软件生成实体结构。通过UG建立包含龈下桩核冠、牙根、牙周膜、皮质骨和松质骨不同组织的三维实体结构,并构建出4组不同程度缺损至牙龈与牙槽骨内的残根且采用龈下桩核冠修复的模型。将构建的模型导入Ansys有限元分析软件中构建有限元模型,并对模型中龈下桩与牙龈和骨接触面的受力及位移进行分析。结果:在Ansys软件中通过不同接触关系的定义和单元网格的划分获得龈下桩核冠修复的不同组织结构有限元模型。4个实验组模型的龈下桩骨接触表面的最大位移均<50μm,最大位移随牙根缺损程度的增加和桩与骨接触面高度的增加而增加。结论:本研究建成的模型具有良好的准确性,能够模拟龈下桩核修复的实际情况。结果提示龈下桩可能与骨接触表面发生骨结合,说明该方法具有一定的可行性,为后续研究打下良好的基础。

AIM： To construct a three dimensional（3D） finite element（FE） model of the post crown with subgingival post for restoration of the maxillary central incisor defected under gingival margin and crest,and to evaluate the feasibility og this newly designed post.METHODS： CT images of an isolated maxillary central incisor obtained through Micro-computed tomography（Micro-CT） were used to produce a 3D solid model of an incisor by CAD software of UG coupled with Mimics10.0 and Geomagic studio10.0.Four models of maxillary central incisor with different defect under crest restored by the newly designed post,including the periodontal ligament and the surrounding part of maxillary cortical and cancellous bone,were constructed by CAD software of UG.All models were imported into ANSYS Workbench to generate the FE model with isotropic material properties.The slidings at the bone-post interface under a lateral force of 120N was compared among different models.RUSLUTS： The FE model was successfully established.The sliding at the bone-post interface of four different models were all under 50 μm and increased with the increment of the bone-post interface.CONCLUSION： According to the results of the study,the method for constructing a FE model is timesavings and efficient.It is feasible to use the newly designed post to restore teeth defected under the margin of gingiva and crest.