[A comparison of stress distribution at tapered vs. threaded cylindrical posts using photoelastic stress analysis].

The need for complex restoration of pulpless teeth has resulted from successful endodontic therapy. When a post and core is necessary thought must be given to the stress producing characteristics of the post. A two-dimensional photoelastic analysis was used to investigate the stress distribution of a tapered post and core and two different core materials on the stress distribution of a threaded cylindrical post. A cast gold tapered post with core, and a prefabricated VLock post with amalgam or composite cores were compared with the VLock post without core at installation, at vertical, and at inclined loading. The findings confirm that tapered posts are benign on installation and that threaded posts create stress where they engage the model, the stresses being intensified upon loading where the posts are in contact with the models. The findings further indicate that cores can facilitate a more favorable distribution, especially at inclined loading.