A practical treatise on artificial crown- and bridge-work by Evans George 1844-1942

Author:Evans, George, 1844-1942
Language: eng
Format: epub, pdf
Tags: Prosthodontics
Publisher: Philadelphia, The S.S. White Dental Mfg. Co.
Published: 1889-03-25T05:00:00+00:00

do Qot hesitate to cut otf the crown, destroy the pulp, and place one of the plate tooth-crowns with a nut. To do so, the crown must be connected to the root by a strip of heavy gold plate, extending for one-quarter of an inch or more,to bring the artificial crown into the circle. For such cases the porcelain crown ^vill also answer."

CHAPTER XIII.

PARTIAL CROWNS.

Gold. —Partial crowns of gold for the protection of plastic fillings in large cavities and for the restoration of contour are often desirable when, for any reason, a solid metallic filling cannot well be inserted. The cavity having been properly excavated, its orifice is trimmed as uniformly straight or circular as its position and character will allow, and the edge of the enamel beveled off, tapering towards the center. In the preparation of cavities in the grinding-surface, trimming and cutting away the enamel should be confined to that surface. In approximal cavities which reach the grinding-surface, it is advisable to

extend them in that surface and bring the gold over Fig. 261. and anchor it there, so as to afford greater security against its displacement in mastication. Where decay extends close to the margin of the gum, if the tooth is trimmed away so that the gold w^U extend just under its free edge, a recurrence of decay at that point will be avoided. The bicuspid shown in Fig. 261 will serve as a typical case to illustrate the constructive details.

The cavity having been properly prepared, a die of the tooth in its original form-is then ^^ecurcd. For this purpose the mold is made by taking an impression of the tooth with wax, making a plaster model, and then restoring the contour and forming from it the mold in gutta-percha or moldiue; or the shape of the natural tooth may be restored with wax or gutta-percha and the mold made directly from it in [)laster. The die and counter-die having been formed (see article on " Molds and Dies "), a piece of pure gold, No. 28 to 30 standard gauge, the exact thickness being governed by the size and nature of a cavity, is struck up to the form and size of the part to be capped. The gold is then

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