US1958446A - Cast metallic denture - Google Patents
Cast metallic denture Download PDFInfo
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- US1958446A US1958446A US1958446DA US1958446A US 1958446 A US1958446 A US 1958446A US 1958446D A US1958446D A US 1958446DA US 1958446 A US1958446 A US 1958446A
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- Prior art keywords
- denture
- alloy
- cast
- chromium
- cobalt
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- 229910045601 alloy Inorganic materials 0.000 description 44
- 239000000956 alloy Substances 0.000 description 44
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical class [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 36
- 239000000463 material Substances 0.000 description 36
- VYZAMTAEIAYCRO-UHFFFAOYSA-N chromium Chemical group [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 34
- 238000004519 manufacturing process Methods 0.000 description 30
- 229910052751 metal Inorganic materials 0.000 description 28
- 239000002184 metal Substances 0.000 description 28
- 229910052804 chromium Inorganic materials 0.000 description 22
- 239000011651 chromium Substances 0.000 description 22
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 22
- 229910052803 cobalt Inorganic materials 0.000 description 22
- 239000010941 cobalt Substances 0.000 description 22
- 238000005266 casting Methods 0.000 description 20
- 238000000034 method Methods 0.000 description 20
- 239000004615 ingredient Substances 0.000 description 18
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 12
- 229910052737 gold Inorganic materials 0.000 description 12
- 239000010931 gold Substances 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 12
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 12
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 12
- 239000007789 gas Substances 0.000 description 10
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 10
- 239000010937 tungsten Substances 0.000 description 10
- 229910052721 tungsten Inorganic materials 0.000 description 10
- 229910001020 Au alloy Inorganic materials 0.000 description 8
- 238000005260 corrosion Methods 0.000 description 8
- 150000002739 metals Chemical class 0.000 description 8
- 229910000531 Co alloy Inorganic materials 0.000 description 6
- 239000000470 constituent Substances 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
- 239000003353 gold alloy Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 229910052742 iron Inorganic materials 0.000 description 6
- 239000000395 magnesium oxide Substances 0.000 description 6
- PWHULOQIROXLJO-UHFFFAOYSA-N manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 6
- 229910052748 manganese Inorganic materials 0.000 description 6
- 239000011572 manganese Substances 0.000 description 6
- ZOKXTWBITQBERF-UHFFFAOYSA-N molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 6
- 239000011733 molybdenum Substances 0.000 description 6
- 229910052750 molybdenum Inorganic materials 0.000 description 6
- 229910052759 nickel Inorganic materials 0.000 description 6
- 239000011505 plaster Substances 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 239000010703 silicon Substances 0.000 description 6
- 239000000377 silicon dioxide Substances 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N AI2O3 Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 210000001909 Alveolar Process Anatomy 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 238000004321 preservation Methods 0.000 description 4
- 239000011819 refractory material Substances 0.000 description 4
- 238000009877 rendering Methods 0.000 description 4
- 239000004115 Sodium Silicate Substances 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N Sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 230000000875 corresponding Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- WMWXXXSCZVGQAR-UHFFFAOYSA-N dialuminum;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3] WMWXXXSCZVGQAR-UHFFFAOYSA-N 0.000 description 2
- 238000002845 discoloration Methods 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 239000005350 fused silica glass Substances 0.000 description 2
- 230000018984 mastication Effects 0.000 description 2
- 238000010077 mastication Methods 0.000 description 2
- 229910001092 metal group alloy Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 229910052755 nonmetal Inorganic materials 0.000 description 2
- 150000002843 nonmetals Chemical class 0.000 description 2
- 230000001105 regulatory Effects 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/07—Alloys based on nickel or cobalt based on cobalt
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
- A61C13/00—Dental prostheses; Making same
- A61C13/08—Artificial teeth; Making same
Definitions
- My present invention relates generally to dental appliances, and has particular reference to dental castings of an improved character and to the method of producing the same.
- one of the principal objectives lies in the provision of a device which accurately conforms, in the minutest detail, to the unique irregularities of m contour and configuration which each specific case involves.
- the device In the case of a denture, for example, whether it be partial or whole, the device must conform accurately to every minute convolution and irregularity of shape or contour 5 of the mouth and jawstructure of the particular individual for whom the denture is intended. Inlays, too, must obviously conform with as nearly perfect accuracy as is humanly possible to the irregularities of the cavity or tooth with which they are to be associated.
- the creation of dental appliances of this general character usually involves the production of a pattern conforming exactly to the special configuration which is involved;
- a swaging process is in many instances satisfactory, especially where a whole denture plate is to be provided.
- a casting procedure is, however, much more preferable as a general rule regardless of the type ofdental appliance that is to be made,
- the strength and resilience are of paramount importance to permit extremely thin and slender portions of the article to maintain their shape under the severe local loads which are constantly imposed during mastication and frequently ,by accidental impact.
- the resilience must be accompanied by an absence of brittleness, and, in fact, there must be sufficient toughness and ductility to withstand overloads and also to permit minor adjustments to be made in configuration, such as during adjustment of a tooth clasp or the like.
- the article should preferably embody a high degree of rigidity, as measured by modulus of elasticity, so as to prevent undue deflection under imposed loads, especially at portions where a constant maintenance of initial acuracy is required.
- the device must have good heat conductivity; it must be homogeneous and sound throughout; and it should preferably be light in weight, and inexpensive.
- the problem of making dentures is further complicated by the requirement that the material of which they are made be corrosionresistant in character. Not only must the finished product withstand oxidation and the action of the acids and other chemicals to which its use will subject it, but it should preferably be of a material which will not discolor and which is capable of maintaining a highly polished and preferably lustrous surface.
- the material to be employed must meet with still further requirements. Obviously, it must be of a character which is capable of being fused or melted in a practical manner. It must have the inherent ability to reharden and to cool without material shrinkage. Also, it must be of a homogeneous character which renders it adaptable to the production of sound castings; and, of course, it must be highly resistant to oxidation and corrosion, and embody the requisite strength, resilience, and. other qualities hereinbefore referred to.
- manganese and silicon may advantageously be increased to no more than 1% each.
- the manganese serves as a deoxidizer during the melting procedure and increases the fluidity of the molten metal. Silicon similarly increases the fluidity. Both manganese and silicon, however, have a tendency to make the alloy brittle, and the proportions should therefore be carefully preserved within the limit specified.
- carbon which is usually present as an impurity, may serve to increase the wearing qualities of the finished article but should preferably be kept well below 1% to avoid brittleness.
- the cobalt may also be combined satisfactorily with more than one of the metals of the chromium group.
- chromium for example, as ; the "essential ingredient, tungsten or molybdenum may sometimes be employed to serve as an additional ingredient, increasing the hardness and resilience of the product, but the amount of such an added ingredient should not exceed 5% and should preferably be below 3%.
- tantalum as an additional ingredient. It has substantially the same effect as tungsten or molybdenum in increasing the resilience of the product. When it is used, the amount should not exceed 5%, and should preferably be below 3%.
- the basic alloy of cobalt and a metal of the chromium group, where the latter ingredient is used within the limits herein illustratively specified, is excellently adapted for my present purposes and obviates many of the disadvantages inherent in gold or gold alloys.
- Gold is popularly used because it is easy to melt and to cast; because it is noble in characteristics, and corrosion-resistant; and because it creates the impression of being of high quality, It has'the tendency to discolor, however, especially when alloyed, as it usually is, with copper or the like; it is relatively expensive; it is somewhat lacking in rigidity; and, of course, it is exceptionally heavy.
- the present material embodies not only a' remarkable strength, resilience, and toughness, permitting even extremely slender denture portions to be cast without sacrifice of form preservation, but it is utterly unsusceptible to discoloration in the mouth; it is comparatively light in weight; and it is relatively inexpensive.
- the presentmaterial embodies also the other specific desirable characteristics which the production of cast dentures calls for. It is highly resistant to corrosion, withstanding even the action of concentrated, boiling nitric acid. It is unaffected by cold sulfuric acid. It undergoes an unusually slight shrinkage during transition from the molten to the solid condition and dur-- ing the cooling of the casting. It is inherently homogeneous and sound. And it has a relatively great heat conductivity.
- the present material fuses at a higher temperature than gold or its alloys, it is preferable to line the mouth of the mold with a highly refractory material and to melt the globule therein. I have also found it satisfactory to fuse the metal in a separate crucible or cup of highly refractory character, arranged alongside of or above the mouth of the mold.
- the rate of cooling is greater than that ordinarily encountered with gold or gold alloy. Special care must therefore be taken to force the molten material speedily and promptly into the mold. This can be accomplished, for example, by using a greater gas pressure means or by forcing the material into the mold with an increased centrifugal force.
- a particular feature of my present process lies in a preferred procedure whereby the metal is melted in a vacuum, and whereby it is thereupon promptly and speedily forced into a mold from which all gases have been exhausted.
- this method of use has a remarkable and unique effect upon a material of the present character, because it not only produces a sounder and more homogeneous casting, devoid of pipes and porosity, but it imparts to the finished product a toughness and resilience which is not otherwis achievable, so far as I am aware.
- the present material when melted and cast in a vacuum, becomes imbued with properties desirable for my present purpose and not achievable to the same degree where ordinary casting procedures are resorted to.
- the vacuum casting procedure has other advantages in connection with the use of the herein described material in that the molten metal is more quickly permitted to enter a delicate mold. Since no gases impede its passage, it fills even intended that these details be the smallest and thinnest portions of the mold with great rapidity and without any of the nonhomogeneity which might otherwise result.
- an artificial cast denture to be used inside the mouth comprising an alloy having a cobalt content of more than fifty percent and including chromium ten to forty per cent, said denture having the characteristic of slight shrinkage in solidifying to provide accuracy of fit and conformity to the mouth and alveolar processes.
- an artificial cast denture to be used inside the mouth comprising an alloy having a cobalt content of more than fifty per cent, including chromium ten to forty percent and tungsten, said denture having the characteristic of slight shrinkage in solidifying to provide accuracy of fit and conformity to the mouth, and alveolar processes substantially without allowance for shrinkage.
- a denture comprising an alloy having cobalt as the principal constituent and containing chromium ten to forty per cent, said alloy denture having the characteristic of slight shrinkage in solidifying.
- a denture comprising an alloy having cobalt as the principal constituent and containing chromium ten to forty per cent, and tungsten, said alloy denture having the characteristic of slight shrinkage in solidifying.
- a denture comprising an alloy having cobalt as the principal constituent and containing chromium ten to forty per cent, and molybdenum, said alloy denture having the characteristic of slight shrinkage in solidifying.
Description
Patented May 15, 1934 UNITED STATES 1,958,446 CAST METALLIC nEN'rUaE Charleen. Prange, Lyndhurst, N. J., assignor to Anstenal Laboratories,'lnc., New York, N. Y.,
a corporation of New York 'REISSUEE) No Drawing. Application March 15, 1932,
v Serial No. 599,071
Claims.
My present invention relates generally to dental appliances, and has particular reference to dental castings of an improved character and to the method of producing the same.
In the production of dentures, either partial or whole, inlays and appliances in general, one of the principal objectives lies in the provision of a device which accurately conforms, in the minutest detail, to the unique irregularities of m contour and configuration which each specific case involves. In the case of a denture, for example, whether it be partial or whole, the device must conform accurately to every minute convolution and irregularity of shape or contour 5 of the mouth and jawstructure of the particular individual for whom the denture is intended. Inlays, too, must obviously conform with as nearly perfect accuracy as is humanly possible to the irregularities of the cavity or tooth with which they are to be associated.
Accordingly, the creation of dental appliances of this general character usually involves the production of a pattern conforming exactly to the special configuration which is involved; and
the consequent manufacture of the appliance in accurate conformity with the pattern. A swaging process is in many instances satisfactory, especially where a whole denture plate is to be provided. A casting procedure is, however, much more preferable as a general rule regardless of the type ofdental appliance that is to be made,
for the reason that greater accuracy and finer conformity with small irregularities can be attained, especially in the case of inlays, partial dentures, and thelike. Y
My present invention has reference to cast dentures, and it will be understood that the term denture as herein used is intended to include within its significance all variety of dental appliances of the general character mentioned, whether they be inlays, crowns, complete or partial plates, or similar allied products.
The problems involved in the production of cast dentures are unique and specialized, since the finished product must comply with a large variety of requirements in order to be of practical value and of the character which the modern state of the art of mechanical dentistry calls for. Briefly, this type of article must embody a pcculiar combination of the qualities of strength, resilience, toughness, and absence of brittleness, whose simultaneous achievement has always presented a problem to those skilled in the art. For example, the finished article must be sufiiciently strong and resilient to yieldably withstand the severe strains and stresses to which it is subjected in use, and to insure a permanent maintenance of the desired initialaccurate contour or configuration. The strength and resilience are of paramount importance to permit extremely thin and slender portions of the article to maintain their shape under the severe local loads which are constantly imposed during mastication and frequently ,by accidental impact. However, the resilience must be accompanied by an absence of brittleness, and, in fact, there must be sufficient toughness and ductility to withstand overloads and also to permit minor adjustments to be made in configuration, such as during adjustment of a tooth clasp or the like. Also, the article should preferably embody a high degree of rigidity, as measured by modulus of elasticity, so as to prevent undue deflection under imposed loads, especially at portions where a constant maintenance of initial acuracy is required. Furthermore, the device must have good heat conductivity; it must be homogeneous and sound throughout; and it should preferably be light in weight, and inexpensive.
In addition to the necessity for meeting the exacting requirements hereinbefore illustratively mentioned, the problem of making dentures is further complicated by the requirement that the material of which they are made be corrosionresistant in character. Not only must the finished product withstand oxidation and the action of the acids and other chemicals to which its use will subject it, but it should preferably be of a material which will not discolor and which is capable of maintaining a highly polished and preferably lustrous surface. I
Gold, and alloys of gold, have been widely used for many years for the reason that they best comply with most, although not all, of the essential requirements.
Where the denture is to be cast, the material to be employed must meet with still further requirements. Obviously, it must be of a character which is capable of being fused or melted in a practical manner. It must have the inherent ability to reharden and to cool without material shrinkage. Also, it must be of a homogeneous character which renders it adaptable to the production of sound castings; and, of course, it must be highly resistant to oxidation and corrosion, and embody the requisite strength, resilience, and. other qualities hereinbefore referred to.
I have found that certain alloys of cobalt, especially alloys of cobalt with a metal or metals of the chromium group, are admirably suited for the so I,
purpose of making cast dentures, particularly where the consistencies and modes of use are carefully controlled and regulated in accordance with the details hereinafter contained.
It has been known for a number of years that cobalt will alloy satisfactorily with one or more of the metals of the chromium group, producing a hard, strong, lustrous, and corrosion-resistant material whose salient characteristics have been its ability to take and retain a cutting edge. Such alloys have therefore come into considerable use in the manufacture of cutlery, saws, lathev tools, and the like. So far as dental work is concerned, however, such alloys have never, so far as I am aware, proven to be feasible or satisfactory. They are, generally speaking, too hard and brittle, too difficult to fuse, and sometimes almost impossible to melt in a practical manner. Though somewhat satisfactorily adaptable to forging at high temperatures', they are, in general, utterly unsuitable for the production of practical results by fine and delicate casting procedures of the character which are involved in the production of dentures.
I have discovered, however, that highly satisfactory cast dentures of even the finest and most delicate grades can be formed of alloys of this general type where the chromium group ingredient is'limited, roughly speaking, to about 10 to 40%, and where the casting procedure is carried out in any of the special modes hereinafter to be described.
For example, I have succeeded in satisfactorily casting dentures composed of a metallic alloy whose essential or principal ingredients are cobalt and chromium, the latter metal being present to the extent of no less than 10 nor more than 40%. I have found that the careful control of the amount of chromium affords the possibility of providing a denture having exactly those characteristics which best fit it for the purposes for which it is intended. Within the approximate range specified, smaller amounts of chromium lend softness and toughness to the denture and render the alloy admirably suited for such articles as inlays, crowns, etc.; while increased amounts of chromium impart correspondingly increased qualities of hardness and resilience to the product, thereby rendering the alloy eminently satisfactory for the production of slender bars, clasps, and other similar parts entering into bridgeand plate-work.
I have also ascertained that small quantities of other metals or non-metals may be advantageously incorporated with the alloy, without injuriously affecting the nature of the alloy, and, in many cases, advantageously modifying its properties and'rendering it more suitable for special requirements. For example, manganese and silicon, usually present as accidental impurities in any event, may advantageously be increased to no more than 1% each. The manganese serves as a deoxidizer during the melting procedure and increases the fluidity of the molten metal. Silicon similarly increases the fluidity. Both manganese and silicon, however, have a tendency to make the alloy brittle, and the proportions should therefore be carefully preserved within the limit specified.
Similarly, carbon, which is usually present as an impurity, may serve to increase the wearing qualities of the finished article but should preferably be kept well below 1% to avoid brittleness.
To increase the toughness and softness of the alloy, for certain particular requirements, I have found it satisfactory to replace the cobalt in part by a metal of the group which comprises iron andnickel. Either iron or nickel, in an amount up to 25%, may be satisfactorily incorporated with the alloy. Nickel may be employed even up to 40%.
The cobalt may also be combined satisfactorily with more than one of the metals of the chromium group. Where chromium is employed, for example, as ;the "essential ingredient, tungsten or molybdenum may sometimes be employed to serve as an additional ingredient, increasing the hardness and resilience of the product, but the amount of such an added ingredient should not exceed 5% and should preferably be below 3%.
In certain cases I have foundv it desirable to employ tantalum as an additional ingredient. It has substantially the same effect as tungsten or molybdenum in increasing the resilience of the product. When it is used, the amount should not exceed 5%, and should preferably be below 3%.
Merely as an example, the following specific ingredients, in substantially the proportions mentioned, have proven to produce a highly satisfactory alloy of the present'character and "for the achievement of the present general objectives:
Chromium 17.50 Cobalt 57.00. Tungsten -4 3.00 Nickel 21.00 Iron s 1.00 Carbon .50
The basic alloy of cobalt and a metal of the chromium group, where the latter ingredient is used within the limits herein illustratively specified, is excellently adapted for my present purposes and obviates many of the disadvantages inherent in gold or gold alloys. Gold is popularly used because it is easy to melt and to cast; because it is noble in characteristics, and corrosion-resistant; and because it creates the impression of being of high quality, It has'the tendency to discolor, however, especially when alloyed, as it usually is, with copper or the like; it is relatively expensive; it is somewhat lacking in rigidity; and, of course, it is exceptionally heavy.
The present material embodies not only a' remarkable strength, resilience, and toughness, permitting even extremely slender denture portions to be cast without sacrifice of form preservation, but it is utterly unsusceptible to discoloration in the mouth; it is comparatively light in weight; and it is relatively inexpensive.
Furthermore, its modulus of elasticity is very high, approaching that of steel, whereas the modulus of elasticity of gold alloys is relatively low. As a result, small elastic parts, such as arms of clasps, may be made exceedingly thin while at the same time they retain suflicient stiffness to be useful. The high degree of rigidity is particu-- larly desirable in parts, such as lingual and palatal bars.
The presentmaterial embodies also the other specific desirable characteristics which the production of cast dentures calls for. It is highly resistant to corrosion, withstanding even the action of concentrated, boiling nitric acid. It is unaffected by cold sulfuric acid. It undergoes an unusually slight shrinkage during transition from the molten to the solid condition and dur-- ing the cooling of the casting. It is inherently homogeneous and sound. And it has a relatively great heat conductivity.
In making a cast denture of a material whose essential ingredients are, as specified, cobalt and a metal of the chromium group, it is essential to employ a mold of a high refractoriness. Whereas the ordinary plaster silica mold, used for gold, will generally withstand preliminary heating up to 1400 Frto drive off gases, the mold which I prefer to employ is one which will withstand a preliminary heating up to 1600 F. This additional preliminary heating serves not only to drive off the gases more efficiently and completely, but it seems to expand the mold by just the proper amount to compensate for the corresponding slight shrinkage that the present alloy undergoes in setting and cooling. I prefer to employ a mold material composed of calcined or fused alumina, calcined or fused silica, or calcined or fused magnesia, with sodium silicate as a binding medium. Molds of plaster and magnesia and of plaster and alumina are also satisfactory, especially when they are lined with a special high-refractory material such as alumina, silica, or magnesia. Such a lining also renders a plaster-silica mold useful for the present purpose.
Since the present material fuses at a higher temperature than gold or its alloys, it is preferable to line the mouth of the mold with a highly refractory material and to melt the globule therein. I have also found it satisfactory to fuse the metal in a separate crucible or cup of highly refractory character, arranged alongside of or above the mouth of the mold.
Because of the higher temperature of the molten metal, the rate of cooling is greater than that ordinarily encountered with gold or gold alloy. Special care must therefore be taken to force the molten material speedily and promptly into the mold. This can be accomplished, for example, by using a greater gas pressure means or by forcing the material into the mold with an increased centrifugal force.
A particular feature of my present process lies in a preferred procedure whereby the metal is melted in a vacuum, and whereby it is thereupon promptly and speedily forced into a mold from which all gases have been exhausted. I have found that this method of use has a remarkable and unique effect upon a material of the present character, because it not only produces a sounder and more homogeneous casting, devoid of pipes and porosity, but it imparts to the finished product a toughness and resilience which is not otherwis achievable, so far as I am aware. In other words, the present material, when melted and cast in a vacuum, becomes imbued with properties desirable for my present purpose and not achievable to the same degree where ordinary casting procedures are resorted to.
The vacuum casting procedure has other advantages in connection with the use of the herein described material in that the molten metal is more quickly permitted to enter a delicate mold. Since no gases impede its passage, it fills even intended that these details be the smallest and thinnest portions of the mold with great rapidity and without any of the nonhomogeneity which might otherwise result.
It will thus be seen that I have provided a method of producing dentures of extreme practical value. The inherent strength and other characteristics of'the material make it possible to produce the thinnest and slenderest kinds of denture parts without sacrifice of inherent strength, rigidity, or resilience. The method of carrying out the casting procedure, preferably by melting and casting the material in a vacuum, permits the material to be cast into these slender shapes with facility and with not only preservation but enhancement of the inherent desirable qualities of the material itself.
It will be obvious that changes in the details herein described for the purpose of explaining the nature of my invention may be made by those skilled in the art without departing from the spirit and scope of the invention as expressed in the appended claims. It is therefore interpreted as illustrative, and not in a limiting sense.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent is- 1. As a new article of manufacture, an artificial cast denture to be used inside the mouth, said denture comprising an alloy having a cobalt content of more than fifty percent and including chromium ten to forty per cent, said denture having the characteristic of slight shrinkage in solidifying to provide accuracy of fit and conformity to the mouth and alveolar processes.
2. As a new article of manufacture, an artificial cast denture to be used inside the mouth, said denture comprising an alloy having a cobalt content of more than fifty per cent, including chromium ten to forty percent and tungsten, said denture having the characteristic of slight shrinkage in solidifying to provide accuracy of fit and conformity to the mouth, and alveolar processes substantially without allowance for shrinkage. I
3. As a new article of manufacture, a denture comprising an alloy having cobalt as the principal constituent and containing chromium ten to forty per cent, said alloy denture having the characteristic of slight shrinkage in solidifying.
4. As a new article of manufacture, a denture comprising an alloy having cobalt as the principal constituent and containing chromium ten to forty per cent, and tungsten, said alloy denture having the characteristic of slight shrinkage in solidifying.
5. As a new article of manufacture, a denture comprising an alloy having cobalt as the principal constituent and containing chromium ten to forty per cent, and molybdenum, said alloy denture having the characteristic of slight shrinkage in solidifying.
CHARLES H. PRANGE.
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE743404C (en) * | 1939-03-26 | 1943-12-24 | Krupp Ag | Use of chrome-cobalt alloys for the production of cold-deformable objects |
US3635703A (en) * | 1969-03-14 | 1972-01-18 | Gregory J Pissarevsky | Ornamental watch case |
US4014691A (en) * | 1972-12-18 | 1977-03-29 | Mohammed M Hamdi A | Dental bridge alloy |
AT394397B (en) * | 1989-04-17 | 1992-03-25 | Haynes Int Inc | CORROSION RESISTANT AND WEAR RESISTANT COBALT BASE ALLOY |
-
0
- US US1958446D patent/US1958446A/en not_active Expired - Lifetime
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE743404C (en) * | 1939-03-26 | 1943-12-24 | Krupp Ag | Use of chrome-cobalt alloys for the production of cold-deformable objects |
US3635703A (en) * | 1969-03-14 | 1972-01-18 | Gregory J Pissarevsky | Ornamental watch case |
US4014691A (en) * | 1972-12-18 | 1977-03-29 | Mohammed M Hamdi A | Dental bridge alloy |
AT394397B (en) * | 1989-04-17 | 1992-03-25 | Haynes Int Inc | CORROSION RESISTANT AND WEAR RESISTANT COBALT BASE ALLOY |
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