Abstract
The purpose of this study was to investigate the stress distribution of all-ceramic crowns made of castable glass ceramics coping with and completely veneered by dental porcelain, using three-dimensional photoelastic stress analysis technique under a static load. Two-layered photoelastic models were made of epoxy resin. Four different loading sites were chosen, and stress was frozen.
The results obtained in each model were as follows:
1. Severe stress was observed in the vicinity of loading sites, and there was a strong possibility of fracture.
2. Relatively low tensile stress was observed at the incisal half of the labial surface and around the cingulum of the lingual surface.
3. Relatively high compressive stress was observed around the labial and lingual cervixes. This is considered to be mesiodistal tensile stress, and may be related to cervical semicircular fracture, with tensile stress around the cingulum.
4. Danger of fracture from the internal surface was suggested.
5. Compressive and tensile stresses tended to decrease in areas away from loading sites, compared to the partially veneered type, and superiority of complete veneered type was indicated.
