[Studies on the mechanical properties of a metal-ceramic restoration. (Part I) Estimation of the bond strength by pull-out test (author's transl)].

Abstract

Metal-ceramic composite materials as a porcelain fused to metal restoration, have been used for biomaterials. But the chief objection, to use of these materials as restorative materials, is its lack of strength, particularly tensile and shear strength. And the materials to have strong bond strength have been studied. On the other hand, the bond strength along metal-ceramic interface have usually measured by a pull out test. At the same time, the objection of the pull out test are pointed out. So, the deformation of metal-ceramic composite materials by the pull out test were simulated to use the axi-symmetric finite element method. And shear stress distribution along the interface and the principal stress distribution in ceramic were calculated. The following results were obtained. (1) Shear stress along the interface and maximum principal stresses in ceramic and in metal decrease rapidly along the interface. (2) The stress concentration factor as the case of the alloy with high Young's modulus is smaller than that of the alloy with low Young's modulus. So, the former would be stronger about the pull out test. (3) Metal-ceramic interface length is not affected for shear stress concentration. If the specimen has more than the critical interface length, the initial crack in ceramic would be occurred at the same pull out force.