WO2003011231A1

WO2003011231A1 - Cobalt-dental alloy

Info

Publication number: WO2003011231A1
Application number: PCT/EP2002/008246
Authority: WO
Inventors: Katja Spohn; Gerolf Bossert; Rudolf Wagner
Original assignee: Wieland Dental + Technik Gmbh & Co. Kg
Priority date: 2001-07-24
Filing date: 2002-07-24
Publication date: 2003-02-13
Also published as: DE10136997A1

Abstract

The invention relates to a cobalt-dental alloy consisting of at least one precious metal, whereby the precious metal represents at least 15-35 wt.- % of the total mass, with the proviso that palladium alone is not contained. Said dental alloy is suitable for producing tight-fitting dentures by deflagration with ceramic materials, and for producing removable dentures. The invention also relates to a dental prosthetic part which is characterised in that it can be produced on the basis of the inventive dental alloy.

Description

Cobalt Dentalleqierunq

description

The invention relates to a cobalt dental alloy with at least one precious metal, its use and a dental prosthetic part made therefrom.

Due to the particularly favorable processing properties and the high corrosion resistance, precious metals and their alloys are very popular in dental technology. In times of high precious metal prices, however, these are quite expensive, so that cheaper non-precious metal alloys, preferably based on cobalt-chromium, which contain no or only small amounts of precious metal, are often used in this area.

However, the non-precious metal alloys have some disadvantages compared to precious metal alloys, including a. as far as the processability of the alloys is concerned. High hardness, poor castability, a lack of ceramic composite combined with a tendency to discolor ceramics when fired, and a lack of corrosion resistance are the most frequently complained disadvantages of cobalt-chromium alloys currently on the market.

DE-A1 -32 44 803 and US Pat. No. 4,253,869 describe cobalt-chromium alloys with 5 or 7-15% by weight of ruthenium, which are said to have a positive effect on the ductility of such alloys.

DE-A1 -199 18 426 describes cobalt-chromium alloys containing noble metals, which contain up to 4% by weight of platinum and up to 5% by weight. Must contain gold in order to no longer have the disadvantages described above.

DE-A1-30 09 650 discloses cobalt-chromium alloys with a palladium content of 1-70% by weight. With palladium contents> 5% by weight, however, it has been shown that the corrosion resistance decreases sharply as the proportion of accompanying metals such as gallium, indium, tin and manganese increases. Et al Therefore, cobalt-chromium alloys that contain only palladium as the noble metal have not found any particular application in the dental field.

Despite certain improvements due to the measures described in the above-mentioned documents, these alloys still show a significantly poorer machinability when milling and polishing compared to precious metal alloys, poorer melting and casting behavior and poor corrosion resistance and a comparatively poor adhesion of baked-on ceramics.

It is therefore an object of the present invention to provide cobalt dental alloys whose properties, in particular their corrosion resistance, come significantly closer to that of the noble metal alloys.

This object is achieved according to claim 1 by cobalt dental alloys with at least one noble metal, the noble metal content being at least 15-35% by weight and palladium not being contained alone. Preferred alloys are described in subclaims 2 to 21. Uses according to the invention and dental prosthetic parts according to the invention result from claims 22 and 23 or 24 to 26. The wording of all claims is hereby made part of the content of this description by reference. By adding the noble metals in the amounts according to the invention, the corrosion resistance can be favorably influenced, the melting and casting behavior can be significantly improved, the CTE (coefficient of thermal expansion) can be set according to the desired expansion, the hardness can be controlled and the machining properties as a whole can be influenced favorably. If, on the other hand, the quantities of noble metal according to the invention are exceeded, the undesirable formation of a less corrosion-resistant phase leads to a drastic reduction in the corrosion resistance. This phenomenon is exacerbated when certain proportions of gallium, indium, tin and aluminum, which preferably do not exceed 12%, are exceeded.

As a rule, the proportion of a single noble metal in the alloys according to the invention is not higher than 25% by weight, preferably not higher than 20% by weight.

The cobalt dental alloys according to the invention preferably contain platinum, rhodium, ruthenium or iridium or mixtures of two or more of the noble metals platinum, ruthenium, rhodium, iridium and palladium. In the case of mixtures, it is preferred if the proportion of platinum is greater than the proportion of the other noble metals.

In further preferred embodiments, the noble metals palladium, platinum, rhodium and ruthenium are contained, wherein the proportion of platinum is preferably higher than the proportion of each of the other noble metals, in particular approximately as high as the total proportion of the other noble metals combined. In another preferred embodiment, the noble metals platinum, ruthenium, rhodium and iridium are contained, the proportion of platinum preferably being higher than the proportion of each of the other noble metals, in particular approximately as high as the total share of the other precious metals combined.

The proportion of noble metal in the cobalt dental alloys according to the invention is advantageously 20-30% by weight, in particular approximately 25% by weight. With regard to the properties of the dental alloys according to the invention, it has proven particularly advantageous if platinum and ruthenium are present as noble metals, and preferably essentially only these. In a particularly preferred embodiment of the dental alloy according to the invention, the proportion of platinum is between 12 and 18% by weight, preferably approximately 15% by weight, and the proportion of ruthenium is between 7 and 13% by weight, preferably approximately 10% by weight .-%.

The alloys according to the invention preferably contain chromium as a constituent, the proportion of this metal being 1-35% by weight, preferably 15-25% by weight, in particular 17-20% by weight. Chromium lowers the CTE and improves corrosion resistance and melting behavior. It also reduces the tendency of the dental alloy to oxidize.

The cobalt proportions of the cobalt dental alloy according to the invention are preferably between 40 and 70% by weight, preferably between 45 and 55% by weight, in particular between 50 and 53% by weight.

In order to achieve certain properties, the dental alloys according to the invention can contain, in addition to the alloy constituents previously mentioned, further metals and / or non-metals as accompanying substances, which are described below. Thus, cobalt dental alloys according to the invention can contain gold, in particular in a proportion of 0.1 to 10% by weight. The share of gold is added to the precious metal share.

In further embodiments of the cobalt dental alloy according to the invention, silver and copper are also present in addition to gold, the total proportion of these metals not exceeding 10% by weight. The metals gold, silver and copper mentioned improve the machinability and the flowability of the dental alloy. Proportions of more than 10% by weight of these three metals reduce the corrosion resistance. In addition, if the concentrations of these metals are too high, dark oxides are formed during the glow, which leads to a deterioration in the aesthetics.

Other preferred embodiments are gold free.

Tungsten and / or molybdenum can be contained in the cobalt dental alloy as further accompanying metals. A content of these metals of 0 to 15% by weight, in particular 0.5 to 10% by weight, is preferred. The metals mentioned improve the corrosion resistance, reduce the tendency to oxidize and lower the CTE. If the preferred proportions by mass of these two metals are exceeded, the machinability of the resulting dental alloys suffers, since in particular the hardness increases significantly.

Furthermore, gallium with a proportion of at most 4% by weight, in particular 0.1-4% by weight, and / or germanium with a proportion of at most 3% by weight, in particular 0.1-3% by weight, can be used as accompanying metals. %, and / or indium with a proportion of at most 4% by weight, in particular 0.1-4% by weight, and / or tin with a proportion of at most 4% by weight, in particular 0.1-4 % By weight, and / or aluminum with a proportion of at most 3% by weight, in particular 0.1-3 % By weight may be present, the total proportion of these metals not exceeding 12% by weight. The total proportion of these metals is in particular in the range from 0.1 to 12% by weight. The melting interval is reduced by these metals, whereby the flowability is increased. In addition, these metals cause the cast porosity to decrease and the bedding behavior to be improved. The influence of these metals on hardness is rather small. If the maximum weight percentages of the individual metals are exceeded, the corrosion resistance will be negatively influenced. In addition, the oxide skin that forms when it melts together with oxygen becomes stronger. It should be noted here that the metals gold, gallium and indium should not be present in the alloy at the same time, since otherwise the individual alloy components may separate during melting. Local elements can form here, which leads to a strong reduction in corrosion resistance. The same applies to a combination of gallium and manganese.

Manganese with a proportion of at most 5% by weight, preferably 0.1-5% by weight, in particular, can be used as additional possible accompanying metals

2% by weight, and / or silicon with a proportion of at most 3% by weight, preferably 0.1-3% by weight, in particular 0.1-1% by weight, and / or

Cerium with a proportion of at most 0.5% by weight, in particular 0.1-0.5

% By weight, and / or boron with a proportion of at most 1.5% by weight, in particular 0.1-1.5% by weight, are contained, the total proportion of these metals not exceeding 5% by weight should and especially in

Range is 0.1 - 5 wt .-%. These accompanying metals increase the

Flowability and cause a faster meltability, which leads to a lower tendency of the melt to overheat. In addition, the fine grain of the presence of the metals mentioned

Dental alloy increased. It should also be mentioned that these metals also as

Deoxidants act. Will the specified maximum values proportions of the individual metals exceeded, this can lead to excessive hardness of the resulting alloy. Corrosion resistance can also suffer.

The cobalt dental alloy according to the invention advantageously contains iron in a proportion of at most 15% by weight, in particular 0.1-15% by weight. This reduces the CTE as well as the hardness of the alloy. However, iron values that are too high lead to an increased tendency to corrosion.

Other accompanying metals are niobium with a proportion of at most 3% by weight, preferably 0.1-3% by weight, in particular 0.5% by weight, and / or tantalum with a proportion of at most 1% by weight. , in particular 0.1-1% by weight, and / or titanium with a proportion of at most 3% by weight, preferably 0.1-3% by weight, in particular 1% by weight, and / or yttrium with a proportion of at most 2% by weight, preferably 0.1-2% by weight, in particular approximately 0.2% by weight, and / or zirconium with a proportion of at most 2% by weight, preferably 0, 1 - 2% by weight, in particular 0.5% by weight, and / or lanthanum with a proportion of at most 1% by weight, in particular 0.1 - 1% by weight, and / or ytterbium with a proportion of at most 1% by weight, in particular 0.1-1% by weight, into question, the total proportion of these metals not exceeding 5% by weight and being in particular in the range of 0.1-5% by weight , These accompanying metals increase the fine grain of the alloy, which leads to an improvement in the mold filling capacity. This in turn lowers the porosity of the castings. In addition, the metals mentioned cause residual N and C components to bond, which leads to a reduction in the brittleness and an increase in the corrosion resistance of the dental alloy. Excessive proportions of the metals mentioned (> 5% by weight) cause an increase in the melting interval and embrittlement of the alloy. In addition to the metals mentioned, non-metals can also be incorporated into the dental alloys according to the invention. For example, carbon and / or nitrogen may be present as accompanying elements with a proportion of at most 0.5% by weight, in particular 0.1-0.5% by weight, the total proportion of these two elements being 0.8% by weight. -% should not exceed and is in particular in the range of 0.1-0.5% by weight. The two elements mentioned lead to an increase in the stiffness (spring hardness) of the alloy. Excessively high proportions (proportions> 5% by weight) cause a strong increase in corrosion due to carbide / nitrite deposits.

A particularly preferred embodiment of a cobalt dental alloy according to the invention has the following composition: cobalt (51% by weight), chromium (19% by weight), platinum (15% by weight), ruthenium (10% by weight), Manganese (2% by weight), silicon (1% by weight) and molybdenum (2% by weight).

Another particularly preferred embodiment of a cobalt dental alloy according to the invention has the following composition: cobalt (50.55% by weight), chromium (18.5% by weight), platinum (15% by weight), ruthenium (10% by weight) %), Manganese (1% by weight), silicon (0.75% by weight), molybdenum (3% by weight), tungsten (0.5% by weight), niobium (0.5 % By weight) and yttrium (0.2% by weight).

With the cobalt dental alloys according to the invention, the production of fixed dentures, preferably by firing with ceramic materials, is possible. In addition, the dental alloys mentioned are suitable for the production of removable dentures.

The invention also claims a dental prosthetic part, which is characterized in that it is based on the dental alloy can be produced according to one of claims 1 to 21. This dental prosthetic part can be veneered with ceramic as well as with plastic, or also not veneered.

Further details and features of the invention result from the following description of preferred embodiments in connection with the subclaims. The respective features can be implemented individually or in combination with one another.

Examples

Table 1 below shows the composition of cobalt dental alloys according to the invention. These alloys are melted in a known manner after the components have been mixed together. They are then available as so-called casting alloys. The table also shows values for hardness, coefficient of thermal expansion, ceramic veneering and corrosion resistance.

The hardness is given in HV 5/30. The coefficients of thermal expansion are given in 10 ^"6 x K ^{" 1} , the first value corresponding to the value measured at 25-500 ° C and the second value corresponding to the value measured at 25-600 ° C. The ceramic veneering ability (metal-ceramic adhesive bond according to ISO 9693) is divided into four levels of differently strong adhesive bond (very good, good, satisfactory, limited). Very good corresponds to> 45 MPa, good corresponds to 35 - 45 MPa, satisfactory corresponds to 25 - 35 MPa and conditionally corresponds to <25 MPa. The corrosion resistance, determined by immersion test according to EN ISO 10271, is divided into three levels (very good, good, satisfactory). Very well corresponds to an ion release of <10 μg / cm ² per week, well corresponds to 10 - 100 μg / cm ² per week, and satisfactorily corresponds to 100 - 1,000 μg / cm ² per week.

Table 1 shows the fundamentally advantageous properties of all tested dental alloys according to the invention. Particularly noteworthy are the alloys with the numbers 8, 9 and 25-35, especially those with the numbers 8 and 31.

Table 1, sheet 2

Claims

claims

1. Cobalt dental alloy with at least one noble metal, the proportion of noble metal being at least 15 to 35% by weight and with the proviso that palladium is not contained alone.

2. Dental alloy according to claim 1, characterized in that a single noble metal is contained with not more than 25% by weight, preferably with not more than 20% by weight.

3. Dental alloy according to claim 1 or 2, characterized in that platinum, ruthenium, rhodium, iridium or palladium or mixtures thereof are contained as the noble metal, with the proviso that palladium is always mixed with platinum, ruthenium, rhodium and / or Iridum is present.

4. Dental alloy according to one of the preceding claims, characterized in that the proportion of platinum is greater than the proportion of the other noble metals.

5. Dental alloy according to one of the preceding claims, characterized in that the noble metal content is 20-30% by weight, preferably approximately 25% by weight.

6. Dental alloy according to one of the preceding claims, in particular according to claim 5, characterized in that platinum and ruthenium are contained as noble metals.

7. Dental alloy according to claim 6, characterized in that the proportion of platinum between 12 and 18 wt .-%, preferably about 15% by weight and the amount of ruthenium is between 7 and 13% by weight, preferably about 10% by weight.

8. Dental alloy according to one of the preceding claims, characterized in that as a further alloy component

Chromium is included.

9. Dental alloy according to claim 8, characterized in that the proportion of chromium is between 1 and 35% by weight, preferably between 15 and 25% by weight, in particular between 17 and 20

% By weight.

10. Dental alloy according to one of the preceding claims, characterized in that the proportion of cobalt is between 40 and 70% by weight, preferably between 45 and 55% by weight.

11. Dental alloy according to one of the preceding claims, characterized in that gold is contained, in particular with a proportion of 0.1 to 10 wt .-%, the proportion of gold being attributed to the noble metal proportion.

12. Dental alloy according to one of the preceding claims, characterized in that gold, silver and copper with a total proportion of at most 10% by weight are contained as accompanying metals.

13. Dental alloy according to one of claims 1 to 10, characterized in that the dental alloy is free of gold.

14. Dental alloy according to one of the preceding claims, characterized in that tungsten as additional accompanying metals and / or molybdenum, each with a proportion of 0.1 to 15% by weight.

15. Dental alloy according to one of the preceding claims, characterized in that gallium with a proportion of at most 4% by weight and / or germanium with a proportion of at most 3% by weight and / or indium with a proportion as further accompanying metals of at most 4% by weight and / or tin with a proportion of at most 4% by weight and / or aluminum with a proportion of at most 3% by weight, the total proportion of these metals not exceeding 12% by weight ,

16. Dental alloy according to one of the preceding claims, characterized in that iron is contained as a further accompanying metal in a proportion of at most 15% by weight.

17. Dental alloy according to one of the preceding claims, characterized in that manganese with a proportion of at most 5 wt.%, Preferably 2 wt.% And / or silicon with a proportion of at most 3, preferably at most 1 wt. -%, and / or cerium with a proportion of at most 0.5% by weight and / or boron with a proportion of at most 1.5% by weight, the total proportion of these metals not exceeding 5% by weight ,

18. Dental alloy according to one of the preceding claims, characterized in that niobium with a proportion of at most 3 wt.%, Preferably 0.5 wt.%, And / or tantalum with a proportion of at most 1 wt. % and / or titanium with a proportion of at most 3% by weight, preferably 1% by weight, and / or yttrium with a proportion of at most 2% by weight, preferably approximately 0.2% by weight, and / or zirconium with a proportion of at most 2% by weight, preferably 0.5% by weight, and / or lanthanum with a proportion of at most 1% by weight and / or ytterbium with a proportion of at most 1% by weight, the total proportion of these metals not exceeding 5% by weight.

19. Dental alloy according to one of the preceding claims, characterized in that carbon and / or nitrogen are contained as additional accompanying elements, each with a proportion of at most 0.5% by weight, the total proportion of these elements

Does not exceed 0.8% by weight.

20. Dental alloy according to one of the preceding claims, characterized in that cobalt with 51 wt .-%, chromium with 19 wt .-%, platinum with 15 wt .-%, ruthenium with 10 wt .-%, manganese with 2 wt. -% silicon, with 1 wt .-% and molybdenum with 2.0 wt .-% are included.

21. Dental alloy according to one of the preceding claims, characterized in that cobalt with 50.55 wt .-%, chromium with

18.5% by weight, platinum with 15% by weight, ruthenium with 10% by weight, manganese with 1% by weight, silicon with 0.75% by weight, molybdenum with 3% by weight, Tungsten with 0.5 wt .-%, niobium with 0.5 wt .-% and yttrium with 0.2 wt .-% are included.

22. Use of the dental alloy according to one of the preceding claims for the production of fixed dentures, preferably by firing with ceramic materials.

23. Use of the dental alloy according to any one of claims 1-21 for the production of removable dentures, preferably by firing with ceramic materials.

24. Dental prosthetic part, characterized in that it can be produced on the basis of the dental alloy according to one of claims 1-21, preferably has a basic structure made of such a dental alloy.

25. Dental prosthetic part according to claim 24, characterized in that it is veneered with ceramic.

26. Dental prosthetic part according to claim 24 or claim 25, characterized in that it is veneered with plastic.