SE449178B - NICKEL-BASED ALLOY AND DENTAL RECONSTRUCTION INCLUDING THIS AND SET TO MAKE DENTAL RECONSTRUCTION - Google Patents

Description

449 178 2 U.S. Pat. Nos. 3,716,418, 3,727 2 §9f 3,749,570 and 3,761,728. an oven.

The higher strength of nickel alloys enables the use of thinner castings, which minimizes the natural tooth structure in preparation for installation of the reconstruction. Nickel alloy reconstructions also have low weight and low thermal conductivity and "these features provide greater comfort to a patient with a sensitive tooth or with a tooth that requires major surgery.

These alloys have a satisfactory bond to porcelain and also have the important economic advantage of having a lower cost than gold alloys or other precious metal alloys. In the known nickel alloys, however, there are certain disadvantages. For example, these alloys are difficult to refine and polish and in this respect require more time in the dental laboratory compared to precious metal alloys. The bond strength of nickel alloys with respect to dental porcelain is sensitive to the repeated firings required during processing and production in the laboratory and this factor can affect the clinical performance of the porcelain and nickel alloy system. It is therefore desirable that a nickel alloy exhibit a high bond strength; which is compatible with the laboratory processing steps associated with the preparation of a reconstruction. Another problem is that slag of known nickel alloys tends to adhere to the clay crucibles used to melt the alloy before casting. It takes time and effort to grind off this solid adhesive slag to avoid possible contamination of other alloys during subsequent castings. D ”b a» ß f? 449 17,8 3 It is believed that these and other problems arise from the use in known alloys of such elements as beryllium, fennel, silicon, gallium and boron, which are added in order to improve melting and casting performance. In contrast to precious metal ingots, which melt into a puddle with little or no slag formation, hitherto known nickel alloy ingots tend to form a separate molten mass, which is covered by a thick slag, upon gas melting. This problem can be at least partially eliminated by the use of the above-mentioned elements but not by creating new problems. gßeryllium, for example, poses a health risk if this metal is not handled with care during alloy production. Alloys containing significant amounts of silicon and gallium tend to become brittle and show an elongation after casting of only approx. 2. fa as a result of the formation of intermetallic compounds. Alloys of this type must be treated at a temperature of 9800 for about 30 minutes, followed by slow cooling in air, in order to obtain sufficient plasticity for edge grinding, and the increased labor cost resulting from this treatment has tendency to eliminate the reduced cost of a base metal alloy. Some other alloys exhibit satisfactory plasticity (over 5% elongation after casting) but microscopic carbides and intermetallic compounds in the alloy result in a more cumbersome and time consuming molding and polishing compared to cast metal alloy castings.

The new alloy according to the invention eliminates the disadvantages of the known nickel alloys while maintaining the above-described advantages of these materials. More particularly, the invention relates to base metal alloys which are characterized by a high nickel-chromium content and which comprise molybdenum, niobium plus tantalum and at least one element belonging to the family of rare earth metals, and to a lesser extent other components, wherein obtains heat expansion properties which closely correspond to the corresponding properties of commercially available dental porcelain, excellent bonding properties with respect to this porcelain, a good plasticity and good forming and polishing properties.

The dental base metal alloy according to the invention has the following composition (the percentages refer to weight percent) "'0 7 Element f 7 * Acceptable content range (%) Nickel a' ss - see 0 Chromium _ f 18 -K23" Molybaen p ~ 1 6 - 10 0 Niob plus tantalum Z 'l _ 4 One or more elements belonging to the rare earth metals. I 0.01 - 5- Iron 0 0.20 -02 Silicon 1 - 0 0 0.01 - 0.5 Manganese '1 0.01 - 0.4 1' lä Titanium - rg 1 0.01 - 0.2 e 1 Aluminum 0 de _ l 0,01 - 1,0 K01 _- 'r: 1 7 0,01 - 0,1 The alloy's relatively high chromium content.and the use of molybdenum gives satisfactory.corrosion resistance when the alloy is exposed to mouth liquids . The intervals given in the table above for other elements are important for ensuring the correct formation of carbide in the alloy (tantalum, nibo; titanium and chromium), for precipitation of gamma-prime phase A, (aluminum and titanium) and for solid solution hardening (molybdenum), all of which factors contribute to the strength and desired plasticity of the finally cast alloy.

Nickel, chromium and molybdenum 'are the elements that primarily determine the heat expansion properties of the alloy, although the other components play a role in this property. One or more elements belonging to the rare earth metals (this refers to the elements having the atomic numbers 57-7l in the periodic table) and the use of alumina 449 178 5 _ nium contribute_ to the alloy being easy to shape and polish ooh provide also good melting and casting properties. Beryllium and tin are not used to make the alloy.

The components are alloyed by induction melting under argon and the rare earth elements constitute the final addition to the melt. The molten alloy is cast into small rods or pellets for convenient remelting when the alloy is to be cast into a denture.

Conventional technology is used to produce a final dental reconstruction with the alloy. A ceramic mold is produced using the usual wax or plastic methods; The alloy is then melted (a gas burner fed with propane at 0.7 kg / cm 2 and oxygen at 1.4 kg / cm 2 is used to achieve the alloy melting point range 1293-1343 ° C) and poured into the mold which is mounted in a centrifugal casting machine. . After cooling, the mold is broken and the casting body is cleaned, trimmed, polished and finished in preparation for the application of porcelain by conventional firing techniques; The polishing of the alloy is performed with conventional equipment, such as with a Shofu Brownie and Greenie rubber wheels. The casting body is imparted a high gloss with an Abbott-Robinson brush (used with a polish) and Blacks felt wheels impregnated with tin oxide. - factory under the trade name VMK-68, by Dentsply International, Inc. under the trade name BIOBOND and by Ceramco Division of Johnson & Johnson. The above dental porcelain generally provides a strong bond to the metal alloy castings of the present invention. The alloys are also useful for making removable dental devices, such as orthodontic holders.

The relative softness of the alloys makes it possible to avoid damage to the surface of the natural teeth over which the device is mounted and the alloys are sufficiently plastic to allow manual shaping for temporary or final fitting of the device. The use of the invention is thus not limited to devices on which porcelain is fired. I Z Strength; Elongation and modulus of elasticity have been measured using an Instron tensile testing instrument. Vickers hardness was measured by a microhardness tester using a diamond cutter. The coefficients of thermal expansion were measured with a dilatometer. These test methods and test instruments are well known in the art. Typical properties of the alloy according to the invention after casting are as follows: V ma Fracture limit 5270 kg / cmz Residual elongation limit (0.2% residual elongation) 1 3780 kg / cmz g Elasticity modulus 1.89 x 106 kg / cmz Elongation a '* 8% Vickers hardness Ip l -200 Coefficient of thermal expansion d 14 x 10-6 ° C_l The invention is further illustrated by the following exemplary embodiments, in which the percentages refer to weight percent.

Examples 1-9 The following dental alloys were prepared with the elements listed in the tables below oçh_halternaš j 094 wF; f? Nickel Chrome Molybdenum Dysprosium Neodymium Niob plus Tantalum Iron 7 “Silicon 'Manganese Aluminum Titanium * Carbon 7 449 1782 Example 1 Example 2 Example 3 63.06 21.60 0.40 1.00 0 3.00 1.25 0.35 0.20 0.10 0.10 0.06 60.54 20:74 8.06 5.00 0 3.64 1.20 0.33 0.27 0.10 0.07 0.05 '62.80 21.76 8.45 0 1.00 3.85 1.25 0.34 0, 27 "0.12 0.10- 0.06 The alloys according to examples 1-3 melt in a way similar to precious metal alloys and form only very thin layers of alloys, which cover the alloy melt.These alloys are easy to shape and polish and show good plasticity for grinding the mold body edges.

Nickel Chrome Molybdenum Samarium Praseodymium Gadolinium Niob plus Tantalum Iron Silicon Manganese Aluminum Titanium Carbon Example 4 Example 5 Example 6, 60.62 62.37 64.18 21.12 20.87 21.22 _ 8.12 8.26 8.34 5.00 0 0 01 3.00 0 O 0 0.50 3.11 3.42 3.71 1.23 1.24 1.20 0.32 0.32 0.30 0.25 0.25 0.28 0, 29 0.10 0.11 0.13 0.08 0.07 0.09 0.05 0.06 0.04 The alloys of these examples are easily digestible and plastic.

Claims (3)

However, the alloys are not formed and polished as easily as the alloys of Examples 1-3. of 'Example 7 Example 8 Example 9 Nickel 20 660 .01 62,99 62,46 Hug p21,00 21,60-21,63 Molybaan 3 8,20. 8.40 0.40 carium _ 2 2.50. 0.50 0.50 Lantan '2 0 1.50 0.50 0.50 Neodymium f 7 0.70 On 0 "Praseodymium 0.30 0" 0 Tenn O, O 0.60 Niob plus tantalum' _ 3.72 3.80 3.80 Iron p I hp pp!, 23- 1.25 .1.25 Silicon 0.32 0.35 _ 0.35 Manganese 3 0 20.26 0.20 '0.20 Aluminum 0 0 0 , 12 0.17 20.07 Titanium 2 p0.09 0 0.10 0.10 “Ü Carbon 0.05_ 0.06 0.06 The alloys according to examples 7-9 are plastic. The alloys according to Examples 7 and 8 are very easy to shape and polish. The alloy of Example 9, which contains tin, is difficult to shape and polish. The alloys of Examples 7-9, upon melting, form a molten mass which is covered with a slightly thicker oxide layer than the alloys of Examples 1f-3. Claim 1. Base metal for dental reconstructions, characterized in that it comprises a body of a stainless metal alloy intended for intraoral installation, the bearing ring comprising ss-se folded nickel, 10-23 weighted chromium, 6-10 weighted malybdenum, 1-4 weight nian plus tantalum and 0.01-5% by weight of at least one rare earth element, which is made of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium or dysprosium. l 2. Dental reconstruction, characterized in that it comprises a body of stainless metal alloy intended for intraoral installation and a porcelain sheath applied to the alloy body by firing, the alloy containing 58-68% by weight of nickel, 18-23% by weight of chromium, 6- 10% by weight of molybdenum, 1-4% by weight of niobium plus tantalum, 0.2-2% by weight of iron, 0.01-0.5% by weight of silicon, 0.01-0.4% by weight of manganese, 0.01-0, 2% by weight of titanium, 0.01%, 0% by weight of aluminum, 0.01-0.1% by weight of carbon and 0701% by weight of at least one rare earth element, which consists of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium or dysprosium 3. A method of producing a dental reconstruction, characterized in that a porcelain sheath is burned on a body of base metal alloy comprising 58-68% by weight of nickel, 18-23% by weight of chromium, 6410% by weight of molybdenum, 1-4% by weight. Niobium plus tantalum, 0.02-2% by weight iron, 0.01-0.5% by weight silicon, 0.01-0.4% by weight manganese, 0.01-0.2% by weight titanium, 0, 01.0% by weight of aluminum, 0.01-0.1% by weight of carbon and 0.01-5% by weight of at least one rare earth element, which consists of lanthanum, cerium, preseodymium, neodymium, samarium, gadolin or dysprosium.