M any ceramometal crowns are constructed with nonprecious alloys, which creates problems to the technician in laboratory procedures and to the patient who is allergic to nickel if nickel-containing alloys are involved. The laboratory procedures are not modified with silver-palladium alloys, but there is a possibility of a green discoloration. Silver melts at 1,761’ F (961’ C) and will varporize above this temperature. The muffle will be impregnated with silver particles that will form compounds with the porcelain and form the green discoloration. The old principle of time and temperature used in ceramics is applied, with the restoration kept in the oven longer to get the same results obtainable at higher temperatures. The temperature is kept lower than 1,760” F when 1,800” F-type porcelain is used. The oven should be purged periodically; a piece of a carbon rod may be used during the baking cycle, but this is not necessary. The metal framework must be cleansed with a sandblaster, preferably a nonrecycling one, with 50 pm aluminum oxide. The restoration is then washed with distilled water in an ultrasonic cleaner for approximately IO minutes. A ceramic conditioner recommended by many manufacturers is applied to form a coat on the metal and prevent future vaporization of the silver in the area to be covered by the porcelain. A greenish gray color will appear on the metal after the cycle when the temperature used is approximately 1,925” F (1,052” C). From there on, the temperature of the oven is never carried higher than 1,761’ F (961’ C) at any time.