[Stress distribution of prefabricated screw posts. Part II: Different designs and materials]

This study compared stress distribution during installation and the functions of prefabricated posts of different designs and materials. When endodontic dowels were installed in standardized models as well as simulated loads were applied, direct comparisons of stress distributing properties were analyzed by photoelastic stress analysis. Based on our findings, we concluded that: 1. During installation and under simulated functional loads, the tapered-end posts produced wedging stresses near the apex. More uniform stress distributions were observed with parallel-sided posts. 2. When the coronal flanges of flange type posts engaged the model around the occlusal portion of the channel preparation, stress concentrations occurred at the flange-dowel-dentin area. Stress levels were reduced toward the apical portion of the dowels. 3. The split shaft of Flexi-Post posts appeared to compress inward, stress concentrations occurred at the cervical and middle third and the other portion of the dowels were reduced. 4. Cementation type posts displayed a low and even distribution of dentinal stress during installation and functional loads.