[Dynamic finite element analysis of three ferrule designs in post crown under impact loading]

To investigate the stress distribution in three ferrule designs in a maxillary central incisor restoration using PFM crown with post, and evaluate the biomechanical mechanism of the ferrule effect in the post crown by 3D finite element dynamic analysis.

The 3D finite element model of a maxillary central incisor restored with post and PFM crown was established. By simulating three types of ferrule effect [crown wrapping dentine (A), core collar wrapping (B), and contrabevel (C)] under dynamic loading, the dentin stress was analyzed.

During dynamic loading, the stress distribution tended to increase from the cervical part to root middle and radical part of the tooth, and greater high stress area was found around the apex of the post, where the peak stress was observed value. The stress of the labial dentin of the root inferior segment increased obviously. The high stress areas were invariable at every loading step during dynamic loading. The peak stress was sigma(vonA)

When the ferrule is 2 mm, the ferrule effect maintained by crown wrapping cervical dentine (A) and core collar wrapping (B) is greater than that maintained by contrabevel (C),but there is no significant difference between A and B. The post with higher elastic modules may cause restore failure due to the high stress at the post apex and labial dentin.