[Stress distribution of prefabricated screw posts. Part I: Post size]

A commonly used prefabricated screw post was analysed for its various lengths and diameters. When endodontic dowels were installed in standardized models, direct comparisons of stress distributing properties were analysed through photoelastic stress analysis. According to the analysis, installation of the post produced severe lateral stress. At shorter lengths, these stress concentrations were much more severe. However, increasing the diameter of the dowel may reduce the stress slightly. Under load conditions, the stress-producing characteristics of the dowel increased with shorter lengths and smaller diameters. It seems that increasing the surface area of insertion with the dentin improves the distribution of the load caused by the insertion of the post.