Objective To investigate the stress intensity and distribution in the dentine of intact endodontically treated mandibular second premolar under three different restorations. Methods Four three- dimensional finite element models were constructed by the data of spiral CT：1）Mandibular second premolar restored directly by full crown；2） Fill the perforating cavity with resin material and full crown restoration；3）Cast nickel chromium（NiCr） alloy post core plus full crown restoration；4）Fiber post and resin core plus full crown restoration. Load was applied on the buccal inclined surface near the top of the buccal cusp and the intensity and distribution of the maximum tensile stress and von Mises stress in the dentine were compared. Results When the tooth was restored with NiCr alloy post core, an obvious stress concentration area was observed in the dentine next to the top of the post. When the fiber post was used, there was little stress concentration area around the top of the post, and the stress distribution in the dentine was almost the same as the control group. No difference of the intensity and distribution of the stress was found with the control group when no post was used and the perforating cavity was just filled with resin material. Conclusion Compared with cast metal post, fiber post is more suitable for post- core crown restorations. In cases with sufficient coronal tooth substance, post is not absolutely necessary and just filling the perforating cavity with resin material followed by crown restoration can be one of the alternative restorations.
