Abstract: Objective: To investigate the effect of different degrees of dentin defect on the stress distribution of post and core restored mandibular premolar by three dimension finite element analysis. Methods: Spiral CT based three-dimensional finite element models of post and core restored mandibular premolar were established. The ferrule heights of the defective area were respectively 0mm, 1mm, 2mm. The defect sites and extent were respectively the whole crown defect, 1/3 of the mesial and distal proximal surface, 1/2 of distal proximal surface, and 1/3 of distal proximal surface. The stress distribution of the defect models restored by fiber post and resin core was analyzed. Results: The maximum shear stress occurred in the whole crown defect models and the models without ferrule. The maximum principal stress appeared in the mesiodistal dentin defect models. Conclusion: Fiber post and resin core restoration should be avoided where the dentin ferrule is not left. When the buccal-lingual dentin width is insufficient, the dentin ferrule height should be increased to secure the fiber post and resin core restoration.

Key words: Three dimensional finite element, Fiber post and resin core, Stress analysis, Mandibular premolar