Creep rate of porcelain-bonding alloys as a function of temperature.

The method of beam bending has been demonstrated for measurement of creep rate as a function of temperature. Representative high gold-, gold-palladium-, and palladium-silver-based alloys have different activation energies for high temperature creep, and thus their relative "sag" behavior is expected to depend on the temperature at which the comparison is made. Near the solidus temperature, creep rates for the alloys investigated differ by an order of magnitude and become increasingly different at lower temperatures. Depending upon the presently unknown mechanisms involved in "sag" and in "margin opening" during porcelain firing, control of activation energy has varying potential for modifying creep-induced discrepancies of PFM restorations.