S i n c e the advent of the cast gold restoration in dentistry, many uses have been made of this method for restoring posterior teeth with proximal lesions. The restorations have ranged (rom simple intracoronal inlays to gold veneer crowns of various types. Of the designs that have been used, some have been based on scientific principles, while others have been rooted in empiricism and tradition. One of the more enduring of the cast restorations has been the Class II inlay? This restoration has been used extensively for 50 years, with many dentists attributing to it advantages which may, in fact, not exist. Cast gold has certain properties which make it superior to silver amalgam,, another material commonly used for Class II restorations. However, many clinicians and researchers have come to realize that, while gold may be stronger and harder, these assets alone do not assure a superior means of restoring Class II lesions. The material itself does not strengthen the remaining tooth structure in a Glass II restoration, that type of restoration being purely intracoronal. Modifications must be made in the design of the preparation to take advantage of the desirable physical properties of the material and to protect the tooth from further breakdown. °-, :~ The purpose of this investigation was to determine the stresses induced at certain critical areas of the tooth by various designs of cast gold restorations when subjected