| Summary: | 碩士 === 臺灣大學 === 臨床牙醫學研究所 === 95 === The restoration of endodontically treated teeth is a topic that is extensively studies and yet remains controversial from many perspective. This study focused on 3D finite element analysis of endodontically treated teeth restored with different types of post-core and crown. Computer tomography scan images were used to construct a model including the actual tooth morphology, and all the necessary structures. Cohesive element of ABAQUS is also used to simulate the adhesive layer between different contact structures including tooth, post, core and crown. A load of 100N was applied to the crown at an angle of 45 degrees, or along the tooth, von Mises (VM ) stresses were calculated. This study consisted of 2 parts: first, a linear, isotropic, completely-bonded 3D finite element study carried out by I-DEAS 9.2; second, was performed with ABAQUS 6.6 in order to simulate cement layer with cohesive element.
The results indicates that: 1. Different VM stress patterns can be caused by the different loading directions, caused different stress concentrations. And common stress concentration areas are: middle of the post at buccal side, between crown margin and alveolar bone at palatal side of the root, and at the junction of post and dentin at post apex. 2. The generated stresses decreased with respect to the post material in the following order: glass fiber, titanium, and zirconia. 3. The ferrule effect resulted in lower stress values in dentin in most cases, but higher values when post-core material is gold. 4. With the application of resin luting agent, in the study loaded with at an angle of 45 degrees, maximum stresses in dentin were decreased and maximum stresses in post were increased. In the study loaded along the tooth, most of the stresses increased.
Within the limitation of this study, it was found that all the investigated factors influenced the stress field generated in post-core restored teeth. Cohesive zone model seems to be a powerful tool to simulate adhesive layer, but further investigations of parameters are needed for better 3D finite element analysis.
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