Fracture properties of human enamel and dentin in an aqueous environment.

SEM fractography and work-of-fracture techniques were used to investigate the fracture properties of human enamel and dentin as a function of the temperature of an aqueous environment. Both enamel and dentin were found to be anisotropic with respect to mechanical failure but were found to have little variation in fracture properties with respect to temperatures from 0 degree to 70 degrees C. Fractographs of a naturally fractured tooth were consistent with experimental findings. The results of this research indicate that natural fracturing of teeth probably cannot be explained on the basis of a reduced work of fracture resulting from chewing hot or cold foods. It was also shown that if dentin surfaces can be kept below 100 degrees C during cavity preparation, the restored tooth will not be weakened by an irreversible reduction of its work of fracture.