Cyclic mechanical fatigue of a feldspathic dental porcelain.

A blunt-indentation fracture mechanics technique was used to investigate the response of a feldspathic dental porcelain to cyclic mechanical fatigue. The indentation stress-strain curve was determined first, which showed the critical pressure necessary for crack initiation. This research also demonstrated that pressures too small to cause immediate catastrophic failure can still cause irreversible damage. A second series of fatigue experiments, using pressure parameters chosen from the first project investigated strength loss. These experiments showed that the porcelain was susceptible to cyclic mechanical fatigue, and that cyclic mechanical fatigue is different from quasistatic fatigue. Strength loss curves indicated that cyclic mechanical fatigue damage is cumulative and permitted quantification of the severity of accumulated damage.