US2089587A

US2089587A - Denture

Info

Publication number: US2089587A
Application number: US112983A
Authority: US
Inventors: Enrique G Touceda
Original assignee: Consolidated Car Heating Co Inc
Current assignee: Consolidated Car Heating Co Inc
Priority date: 1936-11-27
Filing date: 1936-11-27
Publication date: 1937-08-10
Anticipated expiration: 1954-08-10

Description

I Patented Aug. 10, 1931 UNITED. STATES A PATENT OFFICE DENTURE Enrique G. Touceda, Albany, N. Y., assignor to Consolidated Car-Heating Company, Inc., Albany, N. Y., a corporation of New York My invention relates to prosthetic articles and particularly to dentures and the like formed from metal, and preferably but not necessarily, by the process of casting.

In the making of dentures by casting, it is usual to take an impression in plastic material of the interior mouth and jaw structure. This reproduces exactly, in the, plastic, all of the small irregularities of the mouth and jaw structure and is used in making a pattern from which the denture is cast from a suitable metal or alloy.

In order exactly to reproduce in the cast article all the minute structural irregularities in the pattern, the metal used must have many peculiar characteristics among which the following are of paramount importance: It must be highly fluent at casting temperatures because if it is viscous or sluggish when molten it will not run freely into the finer details of the mold.

This is particularly true where a skeleton bridge, plate or other structurehaving finely attenuated portions is being cast, but it is also true in the casting of full or partial plates of paper thickness where it is necessary to produce an article conforming exactly to all of the finer rugae of the patients mouth.

The metal, in the as cast condition, must have a clean surface so that grinding and polishing is substantially unnecessary or at least is re..

39 duced to an absolute minimum. Since the exterior surface of the denture, as cast, conforms to the irregularities of the pattern and since many of these are of an extremely delicate nature, the removal of any substantial portion of the 1 surface of the casting destroys the fit thereof.

The metal used must be such that the shrinkage of the casting on cooling is extremely small otherwise it is impossible to obtain a cast den- 4 ture which fits properly due to the impossibility,

arising from the particular nature of the patacid which is invariably present in the mouth.

The metal must be strong, hard and highly resistant to deformation even in attenuated sections. Yet, on the other hand, it must be capable of being bent to a considerable degree without fracture in order that bridges, clasps and the like may be properly fitted. The yield dentures made therefrom may be subjected to the distortion necessary in close and proper fitting without producing permanent deformation.

The melting point should be as low as possible not only to minimize the .cost and the natural diificulties encountered in casting metals or alloys having extremely high melting points, but also to minimize shrinkage on cooling; and the specific gravity of the composition should also be as low as possible in order that the dentures may be light in weight.

An alloy comprising principally nickel and chromium and containing by weight from to of nickel and from 5% to 30% of chromi.. um affords excellent possibilities for use in making dentures because of its cost as compared with the precious metals and also because of its high resistance to the corrosive agents ordinarily encountered by dentures. However, such a composition is quite soft, the melting point is extremely high, and the alloy when molten is so viscous that it is impossible to cast thin sections therefrom. Moreover, the surface of the alloy in the as cast condition is not suitable for dentures because of the dirt and scale which must be removed therefrom by grinding and polishing.

I find, however, that these undesirable characteristics of, a chromium-nickel alloy of the above type may be eliminated or modified to a suflicient degree to make possible its use in dentures by incorporating therein small proportions of beryllium, say from 0.1% to 5% by weight. While such additions do not affect the highly desirable corrosion resisting characteristics inherent in the chromium-nickel base alloy, they do appreciably lower its melting point, increase its fluidity at casting temperatures to such an extent that extremely attenuated sections may be readily cast, and improve the surface of the casting to such a degree that a very light polishing is all that is required to complete the article. Moreover, the hardness of the alloy and the yield point thereof are substantially increased. In other words, by the addition of beryllium it is possible to make an otherwise totally unsuited alloy extremely well adapted for dentures.

In making my alloy the nickel and chromium are first melted together, and the beryllium, which has a very low specific gravity and is readilyoxidizable, is thereafter added. Due to the lightness of the beryllium, it should be prealloyed with a suitable heavier metal, such as nickel or copper, and the addition made by tying the nickel-beryllium or copper-beryllium to a rod and plunging it into the molten mass. Once the nickel-beryllium or copper-beryllium is wet ,it alloys readily. Just before the molten mass is poured I prefer to add a small amount of calcium, say 0.05% as a deoxidizer.

My preferred composition contains nickel around 80%, and chromium around 20% with suflicient beryllium to obtain the desired results. This will generally be well under 5%, and since beryllium at the present time is quite expensive the quantity employed will naturally be as small as possible. However, the presence of an extremely small quantity of beryllium is readily noticeable in its eflect on the characteristics above mentioned of the alloy; as little as 1%,

for example,- lowering the melting point as much as 120. The efl'ects of the beryllium, however, are more'especially marked when the quantity is in excess of 2%.

In addition to eflecting the essential changes in the base composition above noted, the beryllium, because of its extreme lightness, effects a very substantial reduction in the specific gravity of the composition which is another extremely desirable feature of the alloy when used for deutures.

The term denture as used herein and in the appended claims is to be understood as including inlays, crowns, plates, clasps and other structures intended for use in the mouth, and also prosthetic articles in general.

What I claim is: v

1. A denture formed from an alloy having nickel and chromium as its principal alloying ingredients and containing nickel from 65% to 90%, chromium from 5% to and beryllium from 0.1% to 5%.

2. A cast denture formed from an alloy having nickel and chromium as its principal alloying ingredients and containing nickel from to 90%. chromium from 5% to 30% and beryllium from 0.1% to 5%..

3. A denture formed from an alloy having nickel and chromium as its principal alloying ingredients and containing nickel from to chromium from 15% to 25% and beryllium