US2024545A - Dental alloy - Google Patents

Description

Patented Dec. 117, 1935 JPATENT OFFICE r DENTAL ALLOY James R. Stack, Milford, Del., assignor to The- L. D. Caulk Company, Milford, Del., a corporation of Delaware No Drawing. Application October 4, 1933, I g I Serial No. 692,129

3 Claims. (01. 15-1) I This invention relate to dental alloys and particularly to silver-tin dental alloys containing beryllium.

It has been found that by incorporating relatively small and definite quantities of beryllium 'in silver-tin base dental alloys, the resulting alloy will, upon amalgamation with mercury, exhibit many desirable and beneficial properties. For example, the presence of, proper amounts 4 of beryllium in the alloy in addition to increasing the hardness of both the alloy and the amalgam made therefrom imparts 'a perceptibly higher crushing strength to the latter.-

' Among other features of the invention, is the ability of the amalgam to resist tarnishing and retard corrosion after insertion in the cavity'of the tooth.

In preparing the improved silverftin base a1- loys of the present invention, the constituents may beplaced in a suitable fumace and melted under cover of a non-oxidizing atmosphere.

' Sufiiclent beryllium is incorporated in themelt to yield the desired percentage in the finished alloy. The alloy -may then be cast, milled to the correct particle size and. annealed.

As regards the amount of beryllium incorporated in the alloy, it hasbeen found that the quantity should be sufllcient to constitute not less than 0.06% nor more than 1.0% of the final alloy. ,In other words, at least 0.06% of beryllium is necessary to impart the desirable properties to the alloyrto an appreciable degree,

while if more than 1.0% of "beryllium is used the beneficial effects tend to disappear orare completely nullified. For most silver-tin base dental alloys, a beryllium content lying between the limits of 0.1% to 0.6% appears to give the mostsatisfactoryresults.

It may be preferable from an operat' g standpoint to add the beryllium in some other form than as elemental beryllium. For example, in manufacturing a silver-tin base dental alloy having an appreciable copper content, the ber-yllium may be added in the form of a berylliumcopper ,alloy comprising, for example, 12 beryllium. Again, the alloy may be made by blending a dental alloy containing more than the desired amount of beryllium with a similar dental alloy containing no beryllium. In any event, however, the final product should contain not less than 0.06% or more than 1.0% of beryllium and preferably only 0.1% to 0.6% of 5 that element.

' While the invention is applicable to all silvertin dental alloys, the alloy preferably should conform to the following well recognized speci- Zinc In addition to the "characteristics heretofore mentioned, it has also been found that the presence of beryllium within the limits specified decreases the setting, time of amalgams formed from the alloy. This characteristic is desir- 20 able in some instances. However, the setting time may, if desired, be increased by annealing the alloy at higher temperatures, for example 500 F. or more, than are usually employed in 2% maximum 15 annealing, ordinary silver-tin base dental alloys. 25

' While certain novel features of the invention have been disclosed and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes may be .made by those skilled in the art without de- 30 V parting from the spirit of the invention.

What isclaimed is:

l. A silver-tin base dental alloy containing a minimum of silver, a minimum of 25% tin and from 0.06% to beryllium, which upon 35 amalgamation with mercury exhibits improved hardness and marked resistance to corrosion.

2. A silver-tin base. dental alloy'containing a minimum of 65% silver, a minimum of 25% tin and from 0.1% to 0.6% beryllium, which upon 40 amalgamation with mercury exhibits improved hardness and marked resistance to corrosion.

3. A dental alloy consisting of a minimum of 65% silver, a minimum of 25% tin, copper not exceeding 6%, Zing: not exceeding 2%, and from 45 L 0.06% to 1% beryllium.

- JAMES R. STACK.