Abstract:

BACKGROUND: In the past 3D finite element analysis of post-and-core crown, length and diameter of post were almost analyzed by straggling and combinatorial method that could not precisely reflect their status of continuous variation.
OBJECTIVE: To determine the residual roots stress variation affected by continuous variation of length and diameter of post by Ansys Workbench-DesignXplorer.
METHODS: Parameterization 3-D finite element model of human maxillary central incisor with post-And-Core was created. The range of the post diameter (D) and length (L) were set from 1.0 mm to 4.1 mm and from 3.0 mm to 8.0 mm, respectively by Ansys Workbench.  Influence of the maximum Von Mises stresses in dental tissue by continuous variation of length and diameter of post and sensitivity to D and L were evaluated．
RESULTS AND CONCLUSION: With increasing L, EQV of nickel-chromium alloy post decreased 28.9%, and EQV of carbon fiber post decreased 13.1%; with increasing D, EQV of nickel-chromium alloy post decreased 33.9%, and EQV of carbon fiber post decreased 9.6%. When 5.16 < L < 8.00 and 1.62 < D < 2.02 (nickel-chromium alloy post), 4.75 < L < 8 and 1.68 < D < 2.2 (carbon fiber post), the response curve curvatures of maximum Von Mises stresses to L and D in dentin ranged from -1 to +1. The result has shown that the dentin stress of nickel-chromium alloy post is more sensitive to variation of length and diameter than that of carbon fiber post. diameter of nickel-chromium alloy post have more important influence than length, however, and length of carbon fiber post have more important influence than diameter. Biomechanical natures of different materials should be considered, and the suitable length of nickel-chromium alloy post is 5.16-8.00 mm, and the suitable diameter is 1.62-2.02 mm; the suitable length of carbon fiber post is 4.75-8.00 mm, and the suitable diameter is 1.68-2.20 mm.