Evaluation of mechanical properties of dental ceramic core materials in combination with porcelains

This paper describes the mechanical testing of dental ceramic core materials in combination with porcelains to simulate the real service conditions for dental applications.

The study included Procera AllCeram (densely sintered high-purity alumina); Vita In-Ceram (glass-infiltrated presintered alumina); three dental porcelains (Procera Porcelain AllCeram, Vitadur-N, and Vitadur Alpha); and densely sintered alumina-Procera Porcelain AllCeram two-layer composites, densely sintered alumina-Vitadur-N two-layer composites, and glass-infiltrated presintered alumina-Vitadur Alpha two-layer composites, with different thicknesses of densely sintered alumina or glass-infiltrated presintered alumina, respectively. The flexural tests were performed in ring-on-ring biaxial bending. The flexural failure stresses were determined using both Timoshenko's biaxial loading equation and Shetty's ring-on-ring stress equation. The bending theory of bilayer plates was used to evaluate the failure stresses in the two-layer composites. Weibull statistics were applied to all stress data, and the information was used to estimate the failure probability at selected applied stresses for a comparison of different two-layer densely sintered alumina-porcelain composites.

The failure stress of densely sintered alumina is significantly higher than that of glass-infiltrated presintered alumina as a core dental material under the same testing conditions. The failure stresses of the three commercial dental porcelains are statistically the same.

The results show that the densely sintered alumina-Procera Porcelain AllCeram two-layer composite has interesting dental applications.