Schneider D M, Levi M S, Mori D F
J Prosthet Dent. 1976 Nov;36(5):583-7. doi: 10.1016/0022-3913(76)90309-7.
Eleven direct refractory dies were made from separate polysulfide rubber impressions of two Dentoform teeth which had been prepared for porcelain-fused-to-gold veneer crowns with labial porcelain shoulders. Porcelain veneer crowns were built and fired directly on the dies, following the manufacturer's instructions and using a common laboratory technique. The finished crowns were seated on the Dentoform teeth, and the porcelain-tooth adaptation was measured with a micrometer eyepiece in a dissecting microscope. In general, the study indicated that by use of a direct refractory die, the porcelain adaptation of an average porcelain shoulder veneer crown could be made to fall within the tolerances of a clinically acceptable gold margin (39 mu).21 The crown could likewise be made to adapt closer than the normal thickness of cement film may allow (20 to 40 mu).22 However the adaptation of many crowns was more uneven than the above statements would tend to indicate. The study also showed that with great care and a limited number of firings, margins of a lesser thickness than a piece of 0.001 inch (25.4 mu) platinum foil could be attained. There appears to be promise in the use of a direct refractory die material. However, more studies are needed to overcome some of the problems in the technique described.
从两颗Dentoform牙齿的单独聚硫橡胶印模制作了11个直接耐火代型，这两颗牙齿已制备用于唇侧有瓷肩的烤瓷熔附金属贴面冠。按照制造商的说明并使用常规实验室技术，在代型上直接制作并烧制瓷贴面冠。将完成的冠就位在Dentoform牙齿上，在解剖显微镜下用测微目镜测量瓷与牙齿的贴合度。总体而言，该研究表明，通过使用直接耐火代型，平均瓷肩贴面冠的瓷贴合度可以控制在临床可接受的金边缘公差范围内（39微米）。同样，冠的贴合度可以比正常粘结剂薄膜厚度允许的范围（20至40微米）更紧密。然而，许多冠的贴合度比上述说法所表明的更不均匀。该研究还表明，通过非常小心并进行有限次数的烧制，可以获得比0.001英寸（25.4微米）铂箔更薄的边缘。使用直接耐火代型材料似乎有前景。然而，需要更多研究来克服所描述技术中的一些问题。
