Stress intensity factor threshold in dental porcelains

• Published in: Journal of materials science. Materials in medicine Vol. 19; no. 5; pp. 1945 - 1951
• Main Authors: Yoshimura, Humberto Naoyuki, Cesar, Paulo Francisco, Soki, Fabiana Naomi, Gonzaga, Carla Castiglia
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.05.2008; Springer Nature B.V
• Subjects: Aluminum Silicates - chemistry; Biomaterials; Biomedical Engineering and Bioengineering; Biomedical materials; Ceramics; Ceramics - chemistry; Chemistry and Materials Science; Composites; Dental care; Dental Materials - chemistry; Dental Porcelain - chemistry; Dental Restoration Failure; Dental Stress Analysis - methods; Dentin - chemistry; Glass; Hardness; Materials Science; Materials Testing; Natural Materials; Polymer Sciences; Porcelain; Regenerative Medicine/Tissue Engineering; Saliva, Artificial; Stress, Mechanical; Studies; Surface Properties; Surfaces and Interfaces; Temperature; Thin Films; Water - chemistry; Fracture Toughness; Storage Medium; Radial Crack; Crack Velocity; Al2O3 Content
• ISSN: 0957-4530; 1573-4838
• DOI: 10.1007/s10856-007-3290-4

The stress intensity factor threshold (K I0 ) is related to the stress level at which cracks start to grow stably, causing the weakening of porcelain prostheses during their use. The values of K I0 of seven dental porcelains (with and without reinforcing leucite crystal, KAlSi 2 O 6 ) stored in air (22 °C, 60% relative humidity) and artificial saliva (37 °C) were determined by measuring the crack growth velocity of radial cracks generated at the corner of Vickers indentations. The results of K I0 were correlated with the leucite content, fracture toughness (K Ic ), and chemical composition of the porcelains. It was observed that K I0 increased with the increase of leucite content (only for the leucite-based porcelains) and with the increase of K Ic . The increase in Al 2 O 3 content or the decrease in the alkali oxide (K 2 O and Na 2 O) content of the material’s glassy matrix tended to increase the K I0 values. Storage media (air and saliva) did not significantly affect the K I0 of porcelains tested, indicating that the control parameter of K I0 value was not the water content of the storage media.