RESUMO
OBJECTIVES: To understand the resistance to cyclic and static contact loading of feldspathic porcelain on dental zirconia (3Y-TZP), in order to understand the partial failure of porcelain (chipping or cracking). METHODS: Hertzian contact techniques were used to evaluate the appearance of damage as a ring crack in terms of applied load and number of cycles in air and simulated saliva. RESULTS: Static contact loading showed the presence of stress corrosion cracking in the porcelain; the environmental crack growth in air was determined from the results of time to damage under static load. There was also a contribution of fatigue effects due to the interactions of the crack with the microstructure. From the obtained results, a time to failure was estimated depending on the material counterpart. Cracking can occur on porcelain coatings if the contact counterpart is teeth or porcelain in a time interval of a few years, consistent with clinical studies. SIGNIFICANCE: Contact loading, particularly against teeth or other ceramic materials can be a significant cause of failure and chipping of feldspathic porcelain on zirconia, especially if the patient suffers from bruxism. Protection, by e.g. a guard, against repetitive contact against the porcelain can increase the lifetime of the veneer.
