A comparative strength study of metal ceramic and all-ceramic esthetic materials: modulus of rupture

The modulus of rupture for three metal ceramics and five all-ceramic substructures with and without veneer porcelain was compared. Support of the veneer porcelain was directly related to the modulus of elasticity and not to the strength of the substructure material. The higher the modulus of elasticity, the greater was the strength of the veneered restoration. For each 1 x 10(6) increase in the modulus there was a corresponding 1040 psi increase in strength. The veneered all-ceramics had 45% to 70% of the strength of the metal ceramic restorations. The veneered nonprecious and gold-palladium metal ceramic test bars were significantly stronger than any veneered all-ceramic material.