US872978A - Method for making molds for dental inlays and the like. - Google Patents

Description

PATENTED DEC. 3, 1907.

W. H. TAGGART. METHOD FOR MAKING MOLDS FOR DENTAL INLAYS AND THE LIKE.

APPLICATION FILED JULY 12, 1907.

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WILLIAM H. TAGGART, OF CHICAGO, ILLINOIS.

METHOD FOR MAKING MOLDS FOR DENTAL INLAYS AND LHCE.

Specification of Letters Patent. Original application filed January 12. 1907. Serial No. 351.917. Divided and this Patented 13.0. 3, 1907. application filed .l'nly 12.1907.

Serial No. 383.482.

To all whom it may concern: Be it known that I a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Im- PTOXlllOllt in Methods for Making Molds for Dental Inlays and the Like, of which'the 1 following is a specification.

My mvention relates to a certain new and improved method for making molds for dental inlays and the like, and its object is to provide, by certain novel steps of procedure more fully set forth herein, a method by which molds for such castings can be made with great accuracy and ease. The molds produced by my method are particularly designed for the casting of dental fillings of the type known as inlay fillings, but they can obviously be used for certain other types of work of a fine grade, one of theirprincipal fields of usefulness being in the formation of other types of dental metal work, as, for instance, bridge work and the like.

In the accompanying drawings are shown the various steps of my method as practiced in making a single mold, Figure 1 being a perspective View showing a tooth and the manner in which the pattern is made therein; Fig. 2, a perspective view of the pattern removed; Fig. 3, a perspective view of the pattern showing the sprue former in positlon; Fig. 4, a View showing the pattern and sprue former with the first layer of investing material placed upon the pattern; Fig. 5, a section through the flask and the cover therefor, showing the pattern and first layer of investing material in position therein; Fig. 6, a similar view showing the flask filled with investing material and the flask cover removed Fig. 7, a similar view showing the flask inverted and the pattern in the process of being removed or dissipated and Fig. 8, a section through the completed mold showing it in position'for the casting operation.

This application is a division of an application filed by me on the 12th day of January, 1907, and allotted Serial No. 351,917, the matters herein particularly shown and described and claimed being the method for making the mold, togetherwith the mold itself, the casting process being more particularly claimed in the foregoing application.

As the first step in my process, I form a pattern A, which is illustrated in Fig. 1.

, WILLIAM H. TAGGART,

This pattern is of wax or other plastic ma-. I

terial and is made in immediate contact with the surface which the casting is to I it, so that in making a pattern for a tooth filling it is molded directly in the cavity, the upper surface of the pattern being obtained by having the patient bring the teeth together so that proper articulation is assured. The waxused is of a grade which is plastic at the tempera, ture of the body and which is especially pure so that it can be evaporated and leave hehind no solid residue. After the pattern is formed in the cavity, it is in practice chilled by the application of cool water and is removed from position, it being understood that the cavity is of the form commonly made for inlay fillings either of metal or porcelain, 'i. 0., a cavity without overhangs, so that the pattern can readily be removed without distortion.

After the pattern is removed, a sprue former B having a reduced end I) at one end and a sharp point I) at the other for insertion into the material of the pattern, is secured thereto by thrusting the sharpened end into the face of the pattern, which will be on the outside of the tooth, where a trifling irregularity caused by the removal of the sprue will be of comparatively small consequence... The sprue former is then used as a handle to support the pattern and the entire pattern is covered with a primary coating of investing material C. This investing material may be any one of the various dental investing materials on the market, most of said materials being composed of a mixture of pl aster of paris with some silicious material and with other substances, the compositions of these investing materials varying as they are made by different manufacturers.

It will be understood by those skilled in the art that the dental investment materials vary in quality, some cracking and shrinking. more than others, the better grades of investing materials being less subject to these defects than the poorer grades.

In order to get the best results with my process, the best possible. grade of investing material should be used, but the particular composition of the investing material used has no bearing upon my present invention, although it is of course possible to select an investing material sufficiently poor to produce bad results. In placing this primary body oi; investing material about the pattern,

the greatest care is used to see that there are no air bubbles between the surface of the investing material and the pattern, and a rial has been placed in position, the reduced end I) of the sprue former B is placed in a perforation at the center of a cover 1) of a flask 1C. The center of the cover 1) has a projection roughly hemispherical in form and designated in the drawings by d and it is at the center of this projection that the sprue former is placed. The flask E is then placed in position upon the cover, the parts then occupying the inverted position shown in Fig. 5. A secondary body F of investing material is then poured into the flask around the primary body, so that the flaskis entirely filled with mold material, as shown in Fig. 6. When the investing material is poured in in this manner, 'air bubbles are necessarily formed between the body of mold material and the surfaces with which it contacts and by first placing the primary burner as shown in Fig. 7, and the mold is heated so as to dissipate the wax pattern, the vapors passing ofi through the hole leaving-an unparted mold of the exact form desired. The mold is then completed and may be placed in position upon the casting device, metal may be placed in the crucibleshaped depression G and melted, and the remainder of the operation set forth in the application above identified may be successively performed.

What I claim as new, and desire to secure by Letters Patent, is

1. The process of making patterns for dental inlays and the like, which consists in molding plastic material upon the tooth sur-- face to the size and shape of the desired inlay.

2. The process of making patterns for dental inlays and the like, which consists in molding wax upon the tooth surface to the size and shape of the desired inlay.

3 The process which consists in making a pattern of a tooth filling within the cavity to e filled and in contact with the surface thereof, removing the pattern from the cavity,-

forming about the pattern a mold provided with a sprue, and melting out the pattern.

4. The roeess which consists in forming a pattern or a tooth filling, attaching to the pattern a sprue former, supporting the pattern by means of the sprue former within a flask, and introducing investing material into the flask around the pattern.

5. The process which consists in making a pattern of a tooth filling in the cavity to be filled and in contact with the surface thereof, removing the pattern from the cavity, placing about the pattern a primary body of mold material, adding a secondary bodyof mold material outside the primary body, forming a sprue, and removing the pattern from the mold thus formed.

6. The process which consists in making a pattern for a cast tooth filling within the cavity to be filled and in contact with the surface thereof, from plastic material capable of being changed from its solid condition,

supporting the pattern upon a sprue former, inclosing the attern in a primary body of mold material: supporting the pattern and primary body of mold material within aflask by means of the s rue former, adding a secondary body of mo d material, removing,

sprue former, surrounding the pattern with a primary body of mold material, supporting the pattern and primary body of mold material within a flask by means of the sprue former, ouring in a secondary body of mold materia removing the sprue and volatilizing the wax.

8. The process of making molds for casting dental fillings and the like, which consists in forming a pattern of the desired size and shape, forming a mold about said pattern wit a depression in the mold adapted to form a crucible forming a sprue hole extending from the depression to the pattern and then removing the pattern.

9. The process of making molds for casting dental fillings and the like, which consists in forming a pattern by molding plastic material upon the tooth surface to the size and shape of the desired inlay, forming a mold about said pattern, with a depression in the the flask, in which the sprue former is mounted, said projection forming a depression in the mold which is adapted to form a crucible, filling the flask with investment material, removing the plate carrying the projection and sprne former and then removing the pattern. i

11. The method of forming patterns. for casting dental inlays, which consists in molding plastic material in the cavity to he filled to the size and shape of the desired inlay and obtaining the lower contour of the pattern by cooperation of the plastic material with the cavity wall.

12. The method of forming patterns for 15 WILLIAM H. TAGGART.

In presence of- A. U. TuomEU, R. A. SCHAEFEB.

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