Stress intensity factor threshold in dental porcelains

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Ceramics

Background:

• Dental porcelain prostheses can weaken due to crack growth, initiated at a specific stress level.
• The stress intensity factor threshold (KI0) quantifies this critical stress, impacting the longevity of dental restorations.

Purpose of the Study:

• To determine the KI0 of various dental porcelains.
• To investigate the influence of leucite content, fracture toughness (KIc), and chemical composition on KI0.
• To assess the effect of storage media (air vs. artificial saliva) on KI0 values.

Main Methods:

• Radial cracks were generated at Vickers indentations in seven dental porcelains.
• Crack growth velocity was measured to determine KI0 values.
• KI0 was correlated with leucite content, KIc, and elemental composition.

Main Results:

• KI0 increased with higher leucite content in leucite-containing porcelains.
• Increased fracture toughness (KIc) correlated with higher KI0 values.
• Higher Al2O3 content and lower alkali oxide content (K2O, Na2O) in the glassy matrix increased KI0.
• Storage in air or artificial saliva did not significantly alter KI0.

Conclusions:

• Leucite content and fracture toughness are key factors influencing the stress intensity factor threshold in dental porcelains.
• The chemical composition of the glassy matrix plays a significant role in KI0.
• Environmental conditions like air and saliva have a negligible impact on KI0, suggesting internal material properties are dominant.