3D FEA of post-core design of restoring weakened roots on stress distribution between post&core and tooth interface －Cohesive element approach
Date Issued
2010
Date
2010
Author(s)
Lin, Tung-Hao
Abstract
As improvements on bonding agent, resin cement and fiber post occurred and the concept of『Monoblock』arose, that of which flourished into the idea of using composite resin to strengthen tooth structure, made it possible for the prognosis compromised teeth to kept for rehabilitation! Hence, the concept of restoring excessively weakened endodontically treated tooth becomes different from before and there are more options for treatments. As a result of the modification in the concept, FEA provided numerous studies on excessively weakened endodontically treated tooth in these recent years. Different conclusions can be found in in vitro studies due to differences in methodology in which these methodologies do not closely simulate to the clinical situations and thus the results became unreliable.
The previous related FEA studies cannot simulate the image of the fiber post and root dentin after they are adhered by the cement and often presented fiber post and root dentin as a whole. On one hand, the function of resin cement has been overestimated by doing so and as a result, errors between experimental results and clinic would occur. On the other hand, the interfacial stress and the debonding situation of resin cement cannot be known and the results of the experimental samples cannot be analyzed precisely.
This current study relied on the software Abaqus to simulate excessively weakened endodontically treated tooth and used “cohesive element” to simulate the image (status) of fiber post and dentin being adhered by resin cement. Stress usually occurred on the interface between the tooth and the center of the crown or the post which leads to fractures or debonding along the interface of the tooth that had undergone endodontic treatments. The present study will analyze (1) designs of ferrule; (2) the materials chosen for core and post; (3) the length and width of the post by discussing the intensity and distribution of the stress on the remaining tooth structure. The interfacial stress and debonding condition of resin cement will also be investigated as way of rehabilitation for excessively weakened endodontically treated tooth.
This current study finds out (1) Ferrule effect is more important to fiber post, especially at interface between core and dentin. If it doesn’t have 2 mm ferrule length, the stress of interface will increase 4 times. (2) The material similar to tooth has less stress at interface between post and tooth. The chances of post debonding and post fracture will decrease. (3) If tooth has 2mm ferrule length, we have to choose thinner post; If tooth doesn’t have ferrule length, we have to choose thinner and longer post in order to get better stress distribution.
Subjects
Cohesive element
post
FEA
interface
Type
thesis
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