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In this study a method of measuring interfacial shear stresses from the curvatures of bimaterial dental porcelain-gold strips is described. Stresses were calculated for different porcelain thicknesses and as a function of temperature. The interfacial stresses found ranged from 1,000 psi tensile stress to 3,000 psi compressive stress on the porcelain side of the interface for porcelain thicknesses commonly used in dental restorations.

SYNOPSIS IN INTERLINGUA MAGNITUDE GRANULAR IN FUNDITE ALLICATOS DE AURO.—Le resistentia a traction e le elongamento de auros dental es augmentate quando le magnitude granular es raffinate. Le technica pro le raffinamento del grano in metallos fundite require le regulation del rapiditate con que nucleos de solidification es formate, lo que pote occurrer per nucleation heterogenee o per nucleation homogenee. Le nucleation heterogenee require le dispersion de fin particulas solide in le metallo liquide durante su refrigidaniento. Le nucleation homogenee require superrefrigidamento pro producer nucleos de solidification in le absentia de dispersion. Le rapiditate del nucleation in nucleation homogenee es promovitc quando le energia interfacial inter le nucleos e le liquido es reducite. Un regulation del magnitude del granos esseva effectuate per un regulation del energia de superficie.

Thermal shear stresses that arise from a mismatch of expansion coefficients (Δα) between porcelain and gold alloy can exceed the 13,000 psi shear resistance of the bond. Therefore, calculations of the Aa tolerance were made. A Aa of 0.125 X 10-6 inch/inch/degrees F is safe.