Effects of porcelain/alloy interfacial diffusion zones on thermo-mechanical strain

Chemical bonding between dental porcelains and alloys results from interdiffusion of porcelain and metal ions. An interfacial diffusion zone is created which, most likely, has properties different from those of bulk materials. The changed interface might affect experimental measurements of thermo-mechanical strain. To determine the magnitude and conditions under which this would occur, the interface was modeled as the intermediate layer of a three-layered porcelain-veneered split-metal ring. Layer thicknesses and coefficients of thermal expansion were varied, and the effects on gap change after cooling through 500 degrees C were calculated. Results are presented in a series of 14 Figs., ten curves each, which depict not only interfacial effects, but are extended for use in interpretation of the effects of properties of opaques and glazes as well. Under most conditions, the interface will not affect experimental measurements; some special exceptions are noted.