JPS5916943A - Gold alloy for dental use - Google Patents

Abstract

PURPOSE:To obtain an alloy for dental use which does not form a black oxide film derived from the selective oxidation of Cu during casting but has properties equivalent to those of a conventional gold or gold-silver-Pd alloy for dental use, by the composing the alloy of each specified amount of Au, Pd, Cu and In, and the balance Ag. CONSTITUTION:The alloy for dental use comprising 35-45wt% Au, 5-15wt% Pd, 12-25wt% Cu, 9-20wt% In and the balance Ag. Since said specified amount of In is used, this alloy has excellent properties maching to those of a gold or gold-silver-Pd alloy. In addition, this alloy does not form a black oxide film during casting, so that it is not necessary to treat said alloy with an acid. Furthermore, this alloy is inexpensive, since its gold content is less than that of a gold alloy of 14 carats having the least gold content among the conventional gold ones, and it exhibits a sufficient golden color excellent in aesthetic impression.

Description

[Detailed description of the invention] The present invention is inlays, crowns, bridges, and bars.

This invention relates to a dental gold alloy used when manufacturing dental prostheses such as floors by casting.

Metals used to make prosthetics in dentistry include gold alloys, gold-silver-palladium alloys, silver alloys, nickel and
Although there are chromium alloys, gold alloys are the most preferred because of their physical properties, operability, corrosion resistance in the oral cavity, and aesthetics. That is, silver alloys are not only inferior in physical properties such as tensile strength, elongation, and elongation, but also have problems in discoloration and corrosion resistance in the oral cavity due to silver sulfidation. On the other hand, nickel-chromium alloy has a melting point of about 1200° C., and there is a problem in that it cannot be melted with the mixed flame of city gas or propane gas and air used in ordinary dental casting. Gold-silver-palladium alloys have the same excellent performance as gold alloys in terms of physical properties, operability, and corrosion resistance, but because they are platinum-colored, they are superior to gold-colored gold alloys in terms of aesthetics unique to dentistry. It's inferior.

Usually, gold alloys and gold-silver-palladium alloys contain copper as an element that improves physical properties and provides heat treatment effects, but this copper is very easily oxidized and is selectively oxidized during casting, resulting in black oxidation. Forms a film. Therefore, it is common practice in dentistry to treat the cast body with sulfuric acid, hydrochloric acid, or other processing agents to remove the black oxide film and reveal the original color tone of the alloy, and then to conduct a polishing process. It's a method. However, during this treatment, there are cases where the equipment in the dental laboratory or treatment room is corroded or contaminated due to the acid vapor, and there are cases where the acid or processing agent adheres to clothes or skin during the operation, due to hygiene or safety concerns. There was a problem.

Therefore, as a conventional method to prevent the formation of such a black oxide film, copper is not included in the alloy.

There are alloys in which a deoxidizing agent such as aluminum or silicon is added, and materials in which a reducing agent such as cuprous oxide or graphite is contained in the investment material that serves as the mold.

However, alloys that do not contain copper have insufficient physical properties and heat treatment effects, and alloys that contain deoxidizers such as aluminum or silicon have significantly reduced rolling workability. On the other hand, investment materials that serve as molds contain reducing agents such as cuprous oxide or graphite, which are superior in that they do not reduce the performance of the alloy, but the longer the investment time for the investment material is heated, the more the reducing agent is removed. The effect is weakened and the generation of black oxide cannot be completely suppressed. For this reason, the current situation is that cast bodies are still subjected to acid treatment, and the above-mentioned environmental problems have not been solved.

Therefore, the present inventors have conducted repeated research with the aim of creating an alloy that does not produce a black oxide film due to selective oxidation of steel during casting, without degrading the excellent performance of gold alloys and gold-silver parallum alloys. By effectively using Ingenium L in a specific range of amounts, we have created a new gold alloy that has excellent performance equivalent to gold alloys and gold-silver-palladium alloys, does not generate a black oxide film during casting, and does not require acid treatment. succeeded in creating it. However, this gold alloy is not only economical as it has a lower amount of gold than the 14-strength gold alloy, which has the smallest total amount of conventional gold alloys, but also has a sufficient golden color and is aesthetically pleasing. It can also be said that it is an excellent alloy in this respect.

Hereinafter, the configuration of the present invention and the basis for the numerical limitations will be explained in detail.

The gold alloy of the present invention effectively uses indium in a specific range as a means to prevent the formation of a black oxide film due to selective oxidation of copper during casting, and the indium content is 9 to 20% by weight. stipulated.

Indium is a component that lowers the melting point, improves castability, and enhances the heat treatment effect, but if it is contained in a weight ratio of 9 or more, an indium oxide film may be formed on the surface of the cast body instead of the copper black oxide film. become.

This indium oxide film is formed only on the thin surface layer of the cast body, and its color is pale yellow, reflecting the color tone of the cast body itself. If the indium content is less than 9% by weight, this effect will not be fully exhibited, and if it exceeds 20% by weight, the gold and silver components of the alloy
(To avoid forming intermetallic compounds with radium etc. and weakening the alloy, the effective range of indium is 9 to 20% by weight.
stipulated.

Gold improves the corrosion resistance of the alloy and at the same time gives the alloy a golden color.
It is an important component in imparting heat treatment hardenability to the alloy by precipitating phases such as U5, but if its content is less than 35% by weight, it may deteriorate the corrosion resistance of the alloy. If it exceeds the effective range of 35 to 35, the alloy will form an intermetallic compound with indium, which is a constituent element of the alloy, and the alloy will become brittle.
It was defined as 45% by weight.

Palladium has an effect on the corrosion resistance and discoloration resistance of the alloy, but if the content is less than 5 weight φ, the effect on the corrosion resistance and discoloration resistance is not clear, and on the other hand, if it exceeds 15% by weight, palladium , a strong intermetallic compound is formed between indium, which not only makes the alloy brittle but also raises the melting point and impairs castability. Moreover, in order to eliminate the golden color, the upper limit was set at 15%, and the effective range of palladium was set at 5 to 15% by weight.
stipulated.

Copper is an element that imparts viscous toughness and heat treatment hardenability to the alloy, but if its content is less than 12% by weight, the effects of viscous toughness and heat treatment hardenability will not be fully exhibited, and if the content exceeds 25% by weight, The effective range was set at 12 to 25% by weight in order to degrade corrosion resistance and at the same time promote the formation of a black oxide film.

Iridium and rhodium have the effect of refining the crystal grains of the alloy when added in small amounts, so elements such as these are added for that purpose, but if the amount is less than 10 ppm, the effect of microcrystallization is small, and it is still 11000 ppm. The effective range was defined as 10 to 11,000 pp, since no increase in the microcrystallization performance would be observed even if the amount exceeded 100 pp, and there was a risk that only the hardness would increase.

Platinum is an element that improves the corrosion resistance of the alloy and at the same time imparts heat treatment hardenability, but if it is contained in an amount exceeding 5% by weight, the melting point will rise and castability will be inhibited, so the content should be reduced to 5% by weight. The following is specified.

Zinc and germanium are used as deoxidizing agents, but if they are contained in an amount exceeding 5% by weight, the alloy becomes brittle and rollability is reduced, so the content was specified as 5% by weight or less.

The effects of the present invention will be further explained below with reference to Examples. <
Attachment Table> A comparison was made using a cast body produced according to the formula used to produce the alloys of the Examples and Comparative Examples shown in Table 1.

The tensile strength and elongation values are in accordance with the JIS T6113 test method for 14-carat gold alloy for dental casting, with a diameter of 2 mm'2+.
After casting a round bar with a gauge length of 20 mm and making a test piece,
The sample was subjected to a softening treatment in which it was heated in a 650℃ oven for 15 minutes and then rapidly cooled in water, and after the softening treatment, it was further heated in a 350℃ oven for 30 minutes and then air cooled. It was determined from its maximum tensile strength and elongation at break.

The hardness was measured using a Vickers hardness meter after casting a 15 mm x 10 mm x 1.5 mm plate to prepare a test piece, which was then subjected to the same heat treatment as the tensile test piece.

The discoloration test was carried out in accordance with the JIS T6106 discoloration test for gold, silver and palladium alloys for dental casting, in which the sample was immersed in a 0.1% sodium sulfide solution and held at 37°C for 3 days.

Below, the color tone of the surface of the blank casting body is black in Comparative Examples 1 and 2.4, and a black film was formed due to oxidation of copper, and acid treatment was necessary, but in the case of the alloy of the present invention and Comparative Example 3, the color tone of the alloy itself was black. It exhibited a certain golden color and was able to omit the silicic acid treatment.

As is clear from Table 1, the tensile strength, elongation, and hardness of the alloy of the present invention are 45 to 58 kgf/mm' after softening treatment.
+Elongation 25~33%, hardness 143~178Hv, tensile strength 65~81kgf/mm' after hardening treatment, iFK
): 2 to 6 inches and hardness of 230 to 290 Hv, respectively, showing heat treatment effects, and comparable to Comparative Examples 1, 2, and 3.4 (commercial gold-silver-palladium alloy products and commercial gold alloy products). Better physical properties were obtained.

In addition, Examples 2 and 5.9 have improved tensile strength and elongation compared to Examples 1 and 6.8, and alloys containing iridium and rhodium have improved physical properties as a result of finer crystal grains. The effect of

Furthermore, in Example 13, the increase in hardness due to the hardening treatment was greater than in Example 14, and the effect of increasing heat treatment hardenability due to the platinum content was observed.

Furthermore, these excellent physical properties are stabilized against repeated casting by adding zinc or germanium. Table 2 shows a comparison of the deterioration in tensile strength obtained by repeatedly casting the same alloy five times using each of the alloys of Examples 1, 2, 3, and 5. The alloy of Example 1, which does not contain zinc or germanium, shows a tendency for deterioration to increase as the number of repetitions increases, but the alloys of Example Z and '3°5 maintain stable physical properties even after repeated casting five times. This was recognized.

Table 2: Change in tensile strength due to repeated casting (unit: kgf/mm)
”) In the discoloration test, Example 6 was found to have a slight blackish coloration, but it was within the limited range of JIST6105.

Others showed no discoloration at all and were judged to have sufficient discoloration resistance in the oral cavity.

Further, the melting point was 1000° C. or less in both the examples and the comparative examples, and it was possible to easily melt and cast with a mixed flame of city gas or propane gas and air in a general dental casting method.

The gold alloy of the above 1 invention, which is made of gold, palladium, copper, indium, and silver, and is produced by combining metals such as iridium, rhodium, platinum-zinc, and germanium as required, is a conventional tooth-gum alloy. It has a performance comparable to that of 1, and is also free from the formation of a black film due to copper oxidation during casting.

It is a golden-colored cast body, which solves the environmental problem of not requiring acid treatment, and has excellent physical properties comparable to high-strength rat gold alloys, making it suitable not only for dental clinics but also as a general gold alloy. It can be said that the contribution is extremely significant.

Claims (1)

[Claims] 1. 35-45% by weight of gold, 5-15% by weight of palladium,
A dental gold alloy consisting of 12-25% by weight of copper, 9-20% by weight of indium, and the balance silver. 2. The dental gold alloy according to claim 1, containing 10 to 11,000 pp of iridium. 3. The dental gold alloy according to claim 1, containing 10 to 11000 pp of rhodium. 4 Iridium and rhodium total 10-11000p
The dental gold alloy according to claim 1, which includes p. 5. The dental gold alloy according to any one of claims 1 to 4, containing 5% by weight or less of platinum. 6. The dental gold alloy according to any one of claims 1 to 5, containing 5% by weight or less of zinc. 7. The dental gold alloy according to any one of claims 1 to 5, which contains germanium in an amount of 5 weight or less. 8. The dental gold alloy according to any one of claims 1 to 5, containing 5% by weight or less of each of zinc and germanium.