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This study investigated the loss of a noble alloy during the fabrication of metal crowns. In study found that an average of 29.0% weight of a noble was lost through the various laboratory procedures. The losses were generally higher with maxillary restorations and significantly higher for anterior restorations than for psterior units. The greatest amount of alloy was lost during the preparation of the facial surface for porcelain application. Weight losses resulting from (1) the casting process and cleaning of the casting (2) sprue cutting, (3) seating of the casting onto the die, and (4) preparation for porcelain addition were invested using 323 crowns. The percentage weight losses were 9.80%, l6.46%, 35.69%, and 38.05%, respectivery. Weight losses were generally higher for maxillary restoration, but metal bond porcelain restoration on anterior teeth registered significantly higher losses than those for premolars and molars.
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