Angulation loading effects on cast-gold endodontic posts: a photoelastic stress analysis.

Two-dimensional photoelastic stress analysis was used to investigate the effects of post diameter on stress distribution under angulated (26-degree) loads. Ten models were used; five for each diameter were tested. The models were placed in the straining frame of the polaroscope, and compressive forces of 30 and 60 pounds were applied to each of the models. Instantaneous photographs were made immediately after each load was applied. The fringe patterns were quantitated by determining the maximum fringe order in the test model. The results of this investigation suggest that (1) post diameter should be restricted with heavy anterior masticatory forces and (2) restricting post diameter conserves tooth structure and substantially reduces internal stresses within teeth that have cast-gold posts.