Hand-Carved Porcelain Shell and Other Crowns, Together With Amalgam Model Technique for Crowns and Inlays (Classic Reprint)

If the vital tooth is in a conspicuous position in the mouth a temporary crown made by hollowing out a detached post crown for the anterior teeth or the use of an old gold crown or even a copper band filled with cement for the posterior is indicated, as this serves to hold away the gum from the ledge lying under it and so facilitates the subsequent cementation as well as prevents irritation of the gums lying over the shoulder itself. Leaving teeth in this condition removes the chief occasion for haste in setting the final crown, and makes it possible to carry on more leisurely the necessarily involved laboratory technic. Experience has shown that teeth that are quite sensitive before cementation of a porcelain shell soon become entirely comfortable even to applications of cold water, due to the very high insulating properties of the porcelain. With bell-crowned bicuspids and molars, it is frequently unnecessary to extend the lingual shoulder further gingivally than to the greatest diameter of the tooth, and in many other cases not much more than the enamel is removed. OPERATIVE TECHNIC The operative technic varies with the location of the tooth in the arch, the amount of tooth substance already lost, and the position of the adjoining teeth. Briefly, the object is to reduce the stump to a somewhat conical shape, with its base toward the gum; which base is surrounded by a shoulder or ledge about 0.5 mm. wide and located just under the free margin of the gum. Of course, where deep cavities exist these need only be cut out or filled with cement so as to present a uniform tapering surface, toward the incisal or occlusal, so that an impression of the stump may be withdrawn without distortion. The tapering of the sides is easily done with knife-edged stones, Hall sflexible disks, mounted cylindrical stones, chisels, and burs, but great care is necessary in the prep
(Typographical errors above are due to OCR software and don't occur in the book.)