U.S. patent number 3,819,366 [Application Number 05/259,856] was granted by the patent office on 1974-06-25 for dental alloy.
This patent grant is currently assigned to Aurium Research Corporation. Invention is credited to Michel Katz.
United States Patent |
3,819,366 |
Katz |
* June 25, 1974 |
DENTAL ALLOY
Abstract
A precious alloy for use in dental frames on which ceramic
coverings or acrylic coverings are formed. Palladium is used in an
amount ranging between 8 and 76 weight percent and indium is used
in an amount ranging between 0.2 and 18 weight percent. The
remainder of the alloy consists primarily of gold, or gold and
silver, or silver and small amounts of trace metals. Zinc may also
be included as part of the alloy. With such an alloy, there is no
need for the use of platinum as in the prior art dental alloys and
such alloys, according to this invention, have the same desirable
characteristics as those of the prior art.
Inventors: |
Katz; Michel (Forest Hills,
NY) |
Assignee: |
Aurium Research Corporation
(Long Island City, NY)
|
[*] Notice: |
The portion of the term of this patent
subsequent to June 6, 1989 has been disclaimed. |
Family
ID: |
26947571 |
Appl.
No.: |
05/259,856 |
Filed: |
June 5, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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809381 |
Mar 21, 1969 |
3667936 |
Jun 6, 1972 |
|
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Current U.S.
Class: |
420/463 |
Current CPC
Class: |
A61K
6/844 (20200101); C22C 5/00 (20130101) |
Current International
Class: |
C22C
5/00 (20060101); A61K 6/02 (20060101); A61K
6/04 (20060101); C22c 005/00 () |
Field of
Search: |
;75/134T,165,172R,172G |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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683,004 |
|
Nov 1952 |
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GB |
|
803,379 |
|
Oct 1958 |
|
GB |
|
290,657 |
|
Aug 1953 |
|
GB |
|
Primary Examiner: Rutledge; L. Dewayne
Assistant Examiner: Weise; E. L.
Attorney, Agent or Firm: Amster & Rothstein
Parent Case Text
This invention is a continuation-in-part of application Ser. No.
809,381 filed Mar. 21, 1969, now U.S. Pat. No. 3,667,936 dated June
6, 1972.
Claims
What is claimed is:
1. A material compatible alloy consisting essentially of at least
85 weight percent of a precious metal alloy, said precious metal
alloy including 8-76 weight percent palladium and 0.2-18 weight
percent indium, said compatible alloy further including 0-15 weight
percent zinc, said compatible alloy being free of other trace
metals in amounts greater than 13/4 weight percent.
2. The invention according to claim 1 wherein said precious metal
alloy further includes 0.1-80 weight percent silver and wherein
said compatible alloy includes 0.2-10 weight percent zinc.
3. The invention according to claim 1 wherein said precious metal
alloy further includes 0.1-74 weight percent gold and wherein said
compatible alloy includes 0.2-15 weight percent zinc.
4. The invention according to claim 1 wherein said precious metal
alloy further includes 0.1-78 weight percent gold and 0.1-74 weight
percent silver and wherein said compatible alloy includes 0.2-14
weight percent zinc.
5. The invention according to claim 1 wherein said compatible alloy
includes said precious metal alloy in an amount at least 981/4
weight percent.
6. The invention according to claim 5 wherein said precious metal
alloy includes 0.1-78 weight percent gold.
7. The invention according to claim 5 wherein said precious metal
alloy includes 0.1-74 weight percent silver.
8. The invention according to claim 5 wherein said precious metal
alloy includes 0.1-74 weight percent gold and 0.1-72 weight percent
silver.
Description
This invention relates to dental alloys, and more particularly, to
precious alloys for use in dental frames on which ceramic and
acrylic coverings are disposed.
There are hundreds of different alloys which are used in dental
work for bridges, crowns, inlays, etc. A covering, having an
appearance of a natural tooth, is usually provided on the exterior
of the metal frame. Some of these coverings are of an acrylic
material which is spread on the frame and then hardened while other
coverings utilize "porcelain" which, in actuality, is a ceramic
material, initially in paste form, which is spread on the frame and
then baked. Whether an acrylic or a ceramic material is utilized on
the dental frame, it is important that the dental frame be
compatible with the material which is disposed thereon.
More particularly, when utilizing an acrylic material, it is
important that the hardness of the metal frame be compatible with
that of the acrylic material. Similarly, when a ceramic material is
baked on the dental frame, it is not only required that the
hardness of the frame be compatible with that of the ceramic, but
it is also necessary that the coefficient of thermal expansion of
these two materials be compatible. Still further, it is also
required that the dental frame be of an alloy which will not
discolor the material which is disposed thereon. This is especially
important when the material disposed on the frame is a ceramic.
The present invention relates to precious alloys used in dental
frames. A typical prior art alloy consists of gold (85 percent by
weight), platinum (8 percent by weight) and palladium (5 percent by
weight), with the remaining 2 percent by weight consisting of trace
metals (defined as metals other than precious metals, e.g., copper,
iron or the like) which are primarily for strengthening the alloy.
Precious metals such as gold, platinum and palladium are used to
obtain a white or yellow color which, when baked upon the ceramic
covering, contribute to the simulation of a natural tooth
appearance. Also, such precious metals do not oxidize and thus do
not discolor the ceramic. Because precious metals are generally
soft, hardening agents are included in the alloy. Various
combinations of different precious metals are used, in preference
to an individual metal, primarily to obtain a coefficient of
thermal expansion compatible with that of the ceramic, that is, a
value which permits the two of them to be baked together without
cracks forming in the ceramic.
Conventional dental alloys of this type are very expensive
primarily because of their use of platinum. Although the day-to-day
prices of gold, platinum and palladium vary, approximate respective
prices per ounce are $60, $110 and $35. It is apparent that even
small quantities of platinum can considerably add to the overall
cost of the dental alloy.
Although other alloys are known which eliminate platinum as a part
thereof and although it might be contemplated to utilize these
alloys in dental frames, such is not the case. For example, many of
these alloys include trace metals which are toxic, thereby
precluding their use as a dental frame. Specifically, cadmium, lead
and berrylium have been included as toxic trace metals in these
alloys. Similarly, although yet other alloys do not include these
toxic trace metals, these other alloys for one reason or another,
are not adaptable for use as dental frames. For example, these
latter alloys have included trace metals (such as copper) in
amounts which would discolor any ceramic material disposed on the
dental frame; others have included trace metals which would be too
brittle or otherwise undesirable with the frame covering.
Another problem with prior art alloys has been the high specific
gravity of these alloys. Obviously, it is advantageous to provide a
dental frame alloy having a low specific gravity since this means
that less of the "material" is required in order to form the dental
frame.
It is a general object of my invention to provide a precious alloy
for use in dental frames which is cheaper than those of the prior
art, but of equal quality.
A further object of my invention is to provide a dental alloy which
is compatible with ceramic coverings which are baked thereon.
Yet another object of this invention is to provide a dental alloy
which is compatible with acrylic coverings disposed on the dental
frame.
Another object of this invention is to provide a dental alloy
having a relatively low specific gravity.
Briefly, these and other objects of the present invention are
obtained by providing a dental alloy having an increased palladium
content, such dental alloy enabling decreasing amounts of platinum
to be utilized without sacrificing any of the desirable
characteristics of the prior art. In the prior art, platinum was
required primarily to obtain a low coefficient of thermal
expansion. To harden the alloy, trace metals such as tin and copper
were utilized. Although greater amounts of palladium (instead of
platinum) could be used to lower the coefficient of thermal
expansion (for the case where the dental alloy was utilized with a
ceramic covering), in the prior art there were no known
satisfactory trace metals which could efficiently harden the alloy
with large amounts of palladium. I have found that larger amounts
of palladium can be used, instead of platinum, and that the alloy
can be sufficiently hardened by using a prescribed amount of zinc.
In the alternative, a prescribed amount of indium and/or zinc plus
indium can be utilized to provide the requisite hardness. The
coefficient of thermal expansion for such a ceramic material is
typically in the range between 0.7.times.10.sup..sup.-3 and
0.88.times.10.sup..sup.-3 inch/600.degree. C./inch. Such alloys
according to my invention have the necessary hardness as to be
compatible with ceramic and acrylic coverings; do not discolor
ceramic coverings; are of thermal expansions compatible with
ceramic coverings; and, are not toxic.
It is a feature of my invention to include in an alloy used in
dental frames on which coverings are formed, palladium in an amount
of 8-76 weight percent and indium in the amount of 0.2-18 weight
percent. According to one embodiment of the invention, the dental
alloy should include at least 981/4 weight percent of precious
metal, the term "precious metal" being used to denote gold, silver,
indium, gallium, platinum, palladium, ruthenium, rhodium, osmium,
and iridium. The remaining part of the alloy may include trace
metals (albeit trace metals which are not toxic or which would
otherwise not discolor the ceramic or other material disposed on
the dental frame) in amounts not greater than approximately 13/4
weight percent. According to another embodiment of the present
invention, the alloy includes precious metals in an amount of 85
weight percent, such precious metals including the requisite amount
of palladium and indium mentioned aforesaid. However, with this
embodiment, up to 15 weight percent of zinc may be utilized to
harden the dental alloy.
In accordance with the principles of this invention, I have
provided a dental frame alloy which includes palladium and indium
as the critical ingredients thereof. Additionally (and with the
exception of zinc), the trace metals should be in amounts less than
13/4 weight percent since amounts greater than this produce alloys
which are either too brittle, toxic or otherwise incompatible with
materials disposed on the frame. The dental alloy may also include
silver; gold; gold and silver; zinc and silver; zinc and gold; and,
zinc, gold and silver. The following table summarizes the various
ranges of these materials in weight percentages.
__________________________________________________________________________
Palladium Indium Gold Silver Zinc
__________________________________________________________________________
I 8-76% 0.5-18% 0.1-78% 0.1-74% 0.2-14% II 8-76% 2-18% -- 0.1-74%
-- III 8-76% 4-18% 0.1-78% -- -- IV 8-76% 4-18% 0.1-74% 0.1-72% --
V 8-76% 0.5-18% -- 0.1-80% 0.2-10% VI 8-76% 0.2-18% 0.1-74% --
0.2-15%
__________________________________________________________________________
In accordance with the principles of my invention, I have formed
various dental alloys; wherein the number following each element
represents the amount of that element, by weight percent, and the
specific gravity and hardness are given (unless otherwise
indicated, the hardness is in the terms of the Rockwell B
hardness):
In Accordance With I of the Aforementioned Table:
Example 1:
Palladium (18), Indium (1), Gold (7), Silver (71.6) and Zinc
(2.4);
Specific gravity = 8.4, Hardness = 87.
Example 2:
Palladium (25), Indium (0.5), Gold (62), Silver (8.5) and Zinc
(4);
Specific gravity = 16.0, Hardness = 76.
In Accordance With II of the Aforementioned Table:
Example 3:
Palladium (55.5), Indium (12.3), Silver (32.2);
Specific gravity = 11.0, Hardness = 83.
In Accordance with III of the Aforementioned Table:
Example 4:
Palladium (16.7), Indium (6.8), Gold (76.5);
Specific gravity = 17.5, Bernell Hardness = 154.
In Accordance With IV of the Aforementioned Table:
Example 5:
Palladium (30), Indium (6.5), Gold (50), Silver (13.5);
Specific gravity = 15.6, Hardness = 85.
Example 6:
Palladium (21), Indium (5.5), Gold (66.5), Silver (7);
Specific gravity = 16.3, Hardness = 88.
In Accordance With V of the Aforementioned Table:
Example 7:
Palladium (60), Indium (2.5), Silver (33.5), Zinc (4);
Specific gravity = 11.5, Hardness = 55.
Example 8:
Palladium (60), Indium (2.5), Silver (31.5), Zinc (6);
Specific gravity = 11.5, Hardness = 82.
Example 9:
Palladium (28), Indium (1.0), Silver (66.4), Zinc (4.6);
Specific gravity = 9.1, Hardness = 96.
In Accordance With VI of the Aforementioned Table:
Example 10:
Palladium (52), Indium (0.5), Gold (37.9), Zinc (9.5);
Specific gravity = 15.4, Hardness = 82.
One particular advantage of the alloys according to the present
invention and, more particularly, in the alloy of II and V of the
aforementioned table is the elimination of gold from the alloy.
This is particularly important with the present day "gold crises"
and difficulty and/or undesirability of using gold for many
applications.
In the prior art, it has generally been necessary to roughen the
dental frame prior to placing the material thereon. This was
required, for example, when ceramic coverings are utilized, in
order to properly adhere the ceramic to the dental frame. Another
advantage of my invention is that the use of indium in the
aforementioned ranges does not require roughening the frame in
order that the covering adhere thereon. It is believed that the
indium reacts chemically with conventional ceramic coverings, such
as those sold under various trademarks such as Ceramco, Thermalite,
Vita, etc.
Although the invention has been described with reference to
particular embodiments, it is to be understood that these
embodiments are merely illustrative of the application of the
principles of the invention. Numerous modifications may be made
thereon without departing from the spirit or scope of the present
invention. For example, the alloy according to my invention may be
utilized in other applications wherein the alloy must be compatible
with a ceramic or acrylic material. Thus, my alloy may be utilized
in the jewelry art or the electronic art, etc.
* * * * *