Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C5/00—Alloys based on noble metals
  • C22C5/02—Alloys based on gold
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
  • A61K6/84—Preparations for artificial teeth, for filling teeth or for capping teeth comprising metals or alloys
  • A61K6/844—Noble metals

Definitions

• the invention provides a low melting point precious metal or dental gold alloy consisting of gold, nickel and gallium or gold, nickel, gallium and palladium.
• the yellow gold alloy which consists only of gold, gallium and nickel has a melting point of about 1400 F. and can be cast directly to prefabricated porcelain teeth. Also, it has a high Brinell hardness and high tensile strength.
• the white or platinum colored dental gold alloy which consists of gold, gallium, nickel and palladium, has a melting point of approximately 1500 F., high Brinell hardness, and high tensile strength. Both alloys are tarnish resistant.
• the present invention relates to precious metal alloys and especially to dental gold alloys.
• the present invention provides a dental gold alloy of relatively low melting point and relatively high Brinell hardness which can be cast directly to prefabricated porcelain teeth and which also can be used in making partial dentures, bridgework, crowns, inlays, veneers, orthodontic appliances, and gold Wire supplements,
• dental gold alloys have usually included copper as a hardening element. Copper, however, is a non-precious metal which is attacked by food and other mouth acids and is prone to tarnish.
• dental gold alloys in use today have a preferred carat value of 17 to 18, and usually include in addition to gold, copper and silver, and he quently some small percentages of platinum, palladium or iridium. Such dental golds usually melt around 1700 F. to 1800 F. and higher.
• a further object of the invention is to provide such an alloy which has the natural yellow color of gold and which also can be modified to have a white or platinum color without seriously modifying the physical characteristics of the alloy.
• the present invention which provides a dental gold alloy having a yellow gold color which consists of gold, nickel and 3,574,610 Patented Apr. 13, 1971 gallium; and a dental gold alloy having a white or platinum color which consists of gold, nickel, gallium and palladium,
• the preferred formula for the yellow gold alloy is:
• nickel has a melting point of 2600 F. and that gold has a melting point of 1945" F.
• the addition of the gallium apparently has a direct influence on the nickel and reduces its melting point to an unexpectedly low level. Furthermore, it appears that the gallium acts substantially to harden the nickel in almost the same Way as carbon acts on steel.
• the nickel imparts to the alloy toughness. Copper or silver are currently used in dental gold alloys to impart toughness. However, I have found that the nickel imparts more toughness while the gallium adds the hardness.
• the gallium brings down the melting point to a very desirable level, which in the preferred form of the invention is about 1400 F,
• Another unique aspect of the present invention is from the standpoint of its color. Thus, I have found that even in the preferred formula which contains as much as 18.6% nickel, the yellow gold color is preserved. Thus, I have come to the conclusion that gallium seems to interfere with a change in color from yellow to white. In fact, as pointed out later, I have found it necessary to add from 6% to 8% palladium to change the color of yellow to white.
• alloys embodying my invention do not tarnish in the mouth of the user.
• the yellow gold alloy of the present invention which has a low melting point of about 1400 F. it has been found that this alloy can be directly cast to prefabricated porcelain teeth.
• the porcelain which is generally used by the dental profession is usually fused at a temperature of about 2400 F.
• Dental gold alloys which are currently available usually melt at around 1700 F. to 1800 F. or higher.
• the refractory material used in casting dental gold alloys can only be heated to 1350 F. Hence, it has not been possible heretofore to cast such dental golds melting around 1900 F. directly to prefabricated porcelain teeth in refractory molds which are only heated to 1350 F.
• the alloy does not cool-off sufficiently during casting and hence shocks the porcelain and causes fractures.
• the alloy of the present invention which has a low melting point of about 1400 F. it has been found that the small differential in temperature between the alloy and the refractory mold can be dissipated very quickly and that the porcelain is not fractured by shocks during casting.
• a further advantage of the preferred yellow gold formula of the present invention is that with its high Brinell hardness and its high tensile strength it lends itself to considerably more uses in dental, professional and laboratory work. It can be used in preparing partial dentures, bridgework, crowns, inlays, veneers, orthodontic appliances and gold 'wire supplements, all of which will have improved tensile strength, hardness, and resistance to tarnish.
• Another reason for favoring the preferred formula is that it is an economical formula and reduces the price at which the gold alloy can be sold. With 18.6% nickel and 76.8% gold it is approximately an 18 carat alloy. In dental work a 17 to 18 carat alloy is preferred as a minimum, although there are some economical alloys which are of lesser carat. Other dental alloys currently in use of no higher than 17 to 18 carat are much more expensive because they include platinum, palladium and iridium, all of which add to the cost in comparison with the use of nickel and gallium, "while providing less desirable physical characteristics for the dental gold alloy.
• Gallium 1.5 Nickel 2 l Palladium 6 Gold 71 This is the equivalent of 18 carat gold and has a melting point of about 1500 F. While this alloy can also be cast directly to prefabricated porcelain teeth, I prefer to use the yellow gold formula for this purpose.
• This platinumlike or white gold alloy possesses all of the other advantages of the yellow gold alloy and is especially adapted for use in partial dentures, bridgework, crowns, inlays, veneers, orthodontic appliances, and gold wire supplements. It has the desired high Brinell hardness and tensile strength for such uses. As a general rule I have found that with the white dental gold alloy of the present invention the relationship of the nickel with the gallium should be in the ratio of 6.5% to 1% and that the percentage of palladium should closely approximate 6%, the balance of the alloy being gold.
• gold can be alloyed with nickel and gallium in suitable proportions to produce a yellow gold alloy which has physical and chemical characteristics far superior to the like characteristics of dental gold alloys currently in use; and that by the addition of palladium to such yellow gold alloy I have produced a white gold alloy which also is far superior in physical and chemical characteristics to the dental gold alloys currently in use.
• a precious metal alloy having a melting point above 1350 F. and below 1700 F. of high Brinell hardness and high tensile strength and consisting of nickel from 20% to 5%, gallium from 5% to 1%, and the balance gold.
• a dental gold alloy having a melting point above 1350 F. and below 1700 F., of high tensile strength and high Brinell hardness, and consisting of nickel and gallium in the proportions of 5% nickel to 1% gallium and the balance gold.
• a dental gold casting alloy according to claim 2 having a melting point of approximately 1400 F. and consisting by weight of 4.6% gallium, 18.6% nickel, and 76.8% gold.
• a precious metal alloy according to claim 1 to which has been added approximately 6% palladium with the other elements correspondingly reduced in proportion.
• a dental gold alloy having a melting point of approximately 1500 F. and high Brinell hardness and tensile strength consisting by weight of approximately 6% palladium, nickel and gallium in the ratio of approximately 6.5% nickel to 1% gallium, and the balance gold.
• a dental gold alloy according to claim 5 consisting by weight of 71% gold, 21.5% nickel, 1.5% gallium and 6% palladium.

Landscapes

• Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Plastic & Reconstructive Surgery (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Engineering & Computer Science (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Dental Preparations (AREA)

Applications Claiming Priority (1)

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Cited By (5)

Families Citing this family (1)

• 1968
  • 1968-11-01 US US772794A patent/US3574610A/en not_active Expired - Lifetime
• 1969
  • 1969-10-16 DE DE19691952263 patent/DE1952263A1/de active Pending

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