3-D FEA Of The Premolar With Flat Root Canal Restored With Master Fiber Post Combined With Auxiliary Fiber Post

ObjectiveThe objective was to compare stresses of two3-D models of mandibular first premolar with finite element analysis.Methods1. According to the statistical data reported by Wang Huiyun,19normal mandibular first premolars were chosen and scanned using CBCT. The scanning was conducted perpendicular to the tooth axis with interval of0.1mm.358sectional images were obtained. One premolar with flat root canal was chosen from19and treated by standard RCT procedures. Then post space was prepared in order to simulate clinical practice. After that the prepared tooth was scanned by CBCT again as the first time.2. Mimics, Geomagic studio, CATIA, ANSYS Workbench were used to establish the3-D models A and B. The3-D model which used master fiber post only was named A, and another model that used master fiber post in combination with auxiliary post was named B.3. By ANSYS Workbench two models were loaded by three different directions respectively and the corresponding stress distributions were analyzed.Results 1. Two models were established by CAD.One model which used master fiber post only was named A, and another which used master fiber post in combination with auxiliary fiber post was named B.2. Under three loading directions, the Von mises stress and maximum principal stress of the tooth structure in model B show slightly smaller than model A, but there are no significant differences. High stress area is slightly decreases, and the distribution of stress also tends to be more uniform.3. When loading force and long axis of tooth were angled, the Von mises stress and maximum principal stress of the fiber post in model B show slightly smaller than model A.4. The shear force on the resin mainly concentrate on the tip of the post. Loading with the same angle, the shear force on the resin in model B varies less slightly than model A. Loading with the different angles, the peak value of shear force increase as loading angle increase in the same model.5. As loading angle increase, the peak value of Von mises stress and stress concentration region increase significantly in the same model.Conclusions1. When the loading force angle with the long axis of tooth, the Von mises stress and maximum principal stress on the tooth tissue in model B reduce slightly compare to model A, high stress area decrease slightly, too. And the distribution of stress tend to be more uniform, but isn’t significant.2. Regardless of the model A or B, the high stress area mainly concentrate on the cervix1/3of the root,the peak value of Von mises stress increases significantly as loading angle increases and90°loads may lead destructive effects to the restoration.3. The Influence of auxiliary fiber post to the stress of restoration is less than the loading angle.