US906911A - Tooth crown or plate and swaging device therefor. - Google Patents

Description

y P. B. MGCULLOUGH. jT'ooTH onowN 0B. PLATE AND SWAGING DBVIGE THERMO?.

l` .APILIUATION IILED JULY 27, 1904.

Patented Dech 15, 1908.

UNITED STATES PATENT OFFICE.

PIE,RGY B. MCCULLOUGH, OF PHILADELPHIA, PENNSYLVANIA.

TOOTH CROWN O R-PLATE SWAGING DEVICE TEREI'OR.

To all whom it may concern.' I

Be it known that I, PiERcY' B. MCCrJL- LoUeH, a citizen of the United States, residing in Philadelphia, Pennsylvania,have invented -cert'ain Improvements in Forming Tooth Crowns or Plates and 1n Swaging -Devices Therefor, of whichthe' following is a specification.

One object of my invention is to insure the accurate formation of the occlusal or inasticating surfaces of a'gold tooth' crown without injury to the model, cast `or die u on which the same is formed, a further obyect 4being to provide the dcntistwitli a simple positionl ready for swaging.

Of a numberl of known methods for form# ing the occlusal surfaces. of bicuspid and molar crowns there are two in general use.-

The first provides a metal plate containing `a number of countersunk reproductions of the occlusal surfaces of the bicuspid and y molar teeth. The swaging is done by laying a piece ofgold plate over one of the countersunk impressions, covering4 the late with shot or a piece of lead and then vriving the old into the die by striking the lead with a ammer. The objection to this method is that as the die plates are unchangeable they do not vprovide for the variations in size and form of the teeth of different individuals and at different ages, hence, thel section formed in this manner must be modified.

to fit the band previously fitted to the natural root, or the band must be changed to fit the swaged section thereby destroying the iit of the band -to the natural root. The second method is-to first -fit the gold band to the natural root, then fill it with plaster so that when the patient closes the jaws an impression of the occluding teeth will be formed in the`soft laster.

natural .tooth which it'is desired to reproduce and, frointhe model thus made a matrix isformed in a second' plastic mass, and

l Speccasition of Letters Patent.

Appiicmon mea my 27, 1904. sei-iai No. 213,354.

The. plaster, when hard, 1s carve 'in imitation of the Patenteanee. 15, 190s.

.in said matrix a casting is made with a low fusing alloy, this castingforininga metal die upon which asec'ond casting 1s made,

forming a metal counter die. Between the die and counter die the gold plate is swaged forming the occlusal surface of the crown. This method is objectionable because of the labor which it involves and the diiiculty -in making .a sharp casting with 'a small quantity of metal in a cold matrix and, further, because the method of forming the die and counter die provides no space for the gold plate to be swaged between them, hence any guidelines that may have originally appeared on the die, such, for instance, as those made bythe edges of the band, are entirely destroyed by the force necessary to drive the gold between the dies.

In carrying -out that part of-the crown work preparatory to the swaging operation, I place the band sec-tion upon the root in the mouth and then fill to excess the space within the band with Oxy-phosphate of zinc cement, so that, when the patient closes the jaws, an exact impression ofthe masticating surface o-f the occluding teeth will be formed in said cement. The cement is then carved in imitation of the tooth to be reproduced.

The band section 1 with carved cement 85 cusps 2 is then set in a mass of hard wax 3,

contained in a recess at the end of a mandrel A 4 of 'the swaging 'devicew the cement cuspsv being in relief and the edge of the band exposed, as shown iii Figs. l and 3. A pieceof flat gold plate 5 of the desired thickness vis then placed over the plastic mass 6 which is contained in a recess in the matrix inember 7 ofthe swaging devicev and the cement cusps are driven onto said plate, the latter being trimmed as required until fitted flush 'to the exposededge of the old band l.

- The recess of the man rel member 4 is formed for there'ception of sections of molar crowns, and from the center of this recess extends a sub-recess to admit the pin or pins of biouspid crowns or the roots of natural bic'uspid'teeth. The mandrel is further provided with a finger rest 8 upon which pressure is exerted durin tion and it has abeve ed end 9 correspond ing-to a countersunk 4bevel 10 in the matrix member 7 anddesigned to guide the mandrel to the center during the swaging operation` and'to control the escape of the plastic mass 110 from the recess in the matrix member. The said recess is bounded by `walls which conthe swaging opera verge towards the top, as shown at 11 in Upon the first application of malletl blows upon the mandrel, the plastic material 6 1s driven downwards, then laterally and then v upwards, escaping between the beveled surfaces of the mandrel and matrix plate. As

which the the property of remaining permanently plastic, and hence has the advantage over 4other swaging mediums previously used, such as flour, cornmeal, shot and graphite, that it flows readily under pressure and does not pack. By reason of this difference, I am enabled to effect the swaging operation by the use of a malletl weighing but a' few ounces, instead of ythe much greater force otherwise required. The even distribution of force and the little comparative force required yto swage by this method make it possible to usea natural tooth set in the mandrel as a model or die, and any surface desired can therefore, be reproduced in gold or other suitable metal. Upon the same principle, and after the above described method, a gold orother metal base for a full or partial set4 of artificial teeth may be swaged by'fiXing in a mandrel of sufficient size, a plaster or-builders cement model or a zinc oralloy die of either j aw.

I believe that I am the first to devise a method of swaging plates whereby it is possible to form such a plate directly by the swaging device from a flat piece of metal; other methods require the preliminary shaping of the gold upon amet-al die with a horn mallet.

The forming of the recess in the matrix rvmember 7 of the swaging device with converging walls providesfor-a greater mass of plastic material 6 than would a cylindrical opening extending from the base of the bevel countersink 10, thus providing a more yieldingcushion'for the plate-to be swaged.

The gold plate 5 is placed/upon the lrubber sheet, which thus serves to keep the plate from contact with the plastic mass and facilitates the withdrawal of the swaged plate from the matrix block.

Having thus described my invention, I claim and desire to securefby Letters Patent:

l. The vmode herein described of forming a tooth crown or plate, said mode consisting in first forming a primary cement model of the crown or surface and then by means of said primary cement model, acting directly as a die, pressing a plate of previously unformed malleable metal into a bed of plastic material, substantially as specified.

2. The mode herein described of formingl a tooth crown, said mode consisting in first applying a'band to the natural root of the tooth, then forming, partly within and partly beyond said band, a model of the crown to be produced, and then, by means of'said model, acting directly as a die, forcing a sheet of previously unformed malleable metal into a mass of plastic material, substantially as specified.

3. The mode herein described of forming a tooth crown, said mode consisting in first f applying a band to the natural root ofthe tooth, then forming, partly within and partly beyond said band, a model of the crownto be produced, then setting the band and its contained model, in a mandrel,- so that they project therefrom and form a die, and then directly by means f said die, forcing a sheet of previously unformed malleable metal into a mass oflplasticmaterial, substantially as specified'.

In testimony whereof, I have sig'ed my name to this specification, in the presence of two subscribing witnesses.

PIERCY B. MCCULLOGH. Witnesses:

JAMES MoMoRRIs, Jos. H. KLEIN.

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