CA1132756A

CA1132756A - Material and method for bonding dental metal parts to dental porcelain and other dental metal parts

Info

Publication number: CA1132756A
Application number: CA347,149A
Authority: CA
Inventors: Itzhak Shoher; Aharon Whiteman
Original assignee: Dentaire Ivoclar
Current assignee: Dentaire Ivoclar
Priority date: 1979-03-08
Filing date: 1980-03-06
Publication date: 1982-10-05
Also published as: AU5527780A; EP0016315B1; EP0016315A1; DE3062243D1; AU532799B2

Abstract

ABSTRACT

Material for bonding dental metal parts, especially of noble metals or noble metal alloys with dental porcelain and other dental metal parts, respectively, for making dental restorations, comprising 1 to 100% by weight of one or several noble metal halides and 0 to 99% by weight of a finely divided noble metal component. The invention also relates to a method using said bonding material.

Description

~3;~S6 The present invention relates to a material and a method for bonding dental metal parts especially of noble metals or noble metal alloys to a ceramic, e.g. a dental porcelain, and other dental metal parts, respectively.
It is conventional in the field of restorative dentistry, especially when preparing crowns and bridges, to cover a suitable metal substrate with subsequent layers of ceramic, e.g. a dental porcelain;
the porcelain layers are successively fired on at relatively high temperatures. The metal substrate or substructure is generally of a noble based metal e.g. a noble metal or an alloy of noble metals; in particular, an alloy which is predominantly gold. The dental procelain is generally composed of felspar, quartz and kaolin which may include small additions of other materials. A clinically satisfactory bond between the metal substructure and procelain will depend, among others, upon the coefficient of thermal expansion of the materials used. Since the porcelain is fired onto the metal substrate in layers at elevated temperatures and cooled to room temperature, interfacial stresses between the individual material layers and between metal and porcelain will tend to develop. A satisfactory bond between the metal substrate ~O and the procelain is generally attributed to mechanical retention forces and Van der Waals forces with little, if any, chemical bonding. The I cohesion forces resulting from such bond are invariable weaker than genuine chemical bonds.
Attempts have been made in the prior art to deposit an inter- -mediate layer upon the metal frame-work before firing the porcelain, in order to improve the degree of adhesion of the porcelain to the metal.
For example, reference is made to German Offenlegungsschrift 25 31 113 which suggests the formation of an oxide, e.g. of tin oxide, on the , , :

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metal surface before firing. Although the oxide layer is chemically bonded to the metal framework, the chemical bond between dental porcelain and metal is not significantly improved, and the bond is not unbreakable under clinical conditions.
It is also well-known that adhesion can be promoted by surface preparation of the metal framework. The increase of adhesion following surface preparation is primarily attributable to an increase in Van der Waals forces. Furthermore, bonding materials between metal substructure and dental procelain are known which essentially consist of pure gold powder.
It would be advantageous to have a clinically unbreakable bond between metal substructure and dental porcelain, or between dental metal parts, respectively. It would also be advantageous to reduce the tensions between the individual layers.
The present invention provides a bonding material suitable for bonding a dental metal part to dental porcelain or to another dental metal part for making dental restorations characterized in that said bonding mat-erial comprises 1 to 99.9% by weight of at least one noble metal halide and 0.1 to 99% by weight of a finely divided noble metal component.
The invention also relates to a method for making dental restorations ~0 by bonding a dental metal part, especially a dental metal part made of a noble metal or noble metal alloy either to dental porcelain or to another dental metal part characterized in that a bonding material after being applied to a metal substructure or substrate is sintered or fired thereon at a high temperature to provide a pretreated dental metal part; dental porcelain may be applied over said sintered coating and fired thereon; the method for the present invention is characterized by

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~3~'~'S6 the use of the above-mentioned bonding material.
In particular, the present invention provides a method for preparing a pretreated dental metal part suitable for making a dental restoration by bonding said pretreated dental metal part to dental porcelain or to another dental metal part~ characterized in that a suitable metal substrate on which a bonding material has been applied is subjected to a high temperàture to sinter or fire said bonding material thereon, said bonding material comprising 1% to 100% by weight of at least one noble metal halide and 0% to 99% by weight of a finely divided noble metal component.
The present invention also provides a method for making a dental restoration by bonding a dental metal part to dental porcelain characterized by the steps of (a) applying a bonding material to a suitable metal sub-strate, said bonding material thereafter being sintered or fired thereon at a high temperature, said bonding material comprising 1% to 100% by weight of at least one noble metal halide and 0% to 99% by weight of a finely divided noble metal component, and ~ (b) applying dental porcelain over said sintered or fired bonding material and firing said dental porcelain thereon.
The invention provides a clinically unbreakable bond between metal and dental porcelain, or between two dental metal parts; the-oretically, it is not yet completely clear how such a bond is formed.
The formation of the bond may be explained by assuming that a chemlcal bond is first formed between, e.g. a dental metal substrate and the bonding material. The bonding material wlll then react with the other dental metal part or with the dental porcelain. In the last-mentioned - :

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case, the tensions within the dental porcelain are probably reduced, and a chemical bond to the dental porcelain itself is produced.
Preferably, the bonding material according to the invention contains 1% to 99.9% by weight of one or several noble metal halides and 0.1% to 99% by weight of a finely divided noble metal component.
The noble metal halides used are preferably the halides of metals in the group consisting of silver, platinum,palladium and gold;
halides of other noble metals, for example, osmium, rhodium and iridium being less preferred. Preferably, the halides used are those containing the noble metal chlorides, noble metal fluorides and mixtures thereof;

the noble metal bromides and iodides may also be used. The preferred noble metal halides are silver chloride, silver fluoride, gold chloride, gold fluoride and mixtures thereof.
The noble metal component may contain or consist of noble metals or alloys thereof; preferably it is at least predominantly com-posed of a metal such as one selected from gold, silver, platinum, palladium and mixtures thereof.
The "~oble metàl component" may consist of:

(a) particles of pure noble metal (b) particles of alloys of two or more noble metals (c) physical admixtures of (a) or (b) above (d) embodiments (a), (b) and (c) wherein minor amounts of non-noble metals are present as alloy components and/or in physical admixture therewith.
The "noble metal component" may be a metal or metal alloy containing one or more noble metal consituents which represents all or a relatively substantial portion by weight of such~metal or metaI alloy.

The preferred noble metal is gold and/or silver. Furthermore, palladium . .- : -- . :
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and/or platinum are suitable ~hereas rhodium, osmium and iridium are less preferred.
A preferred noble metal component contains at least 50 % by weight of gold whereas the residue comprises about 0 to 45% of a metal selected from the group consisting of silver, platinum, palladium, and rhodium and mixtures thereof; and about 0 to 5% by weight of a base metal selected from the group consisting of copper, zinc, iron, tin, cadmium, manganese, germanium, magnesium cobalt, nickel and miY.tures thereof; the noble metal component may consist of particles of a metal or metal alloy.
The finely divided noble metal component may be used in any suitable form, e.g. in the form of flakes, granules or powder. The particle size of the noble metal component may be 60 microns or less, e.g. preferably between about 1 and 60 microns (~m), and a particle size of below 10 microns (~m) is preferred. An optimum particle size range is between about 1 and 10 microns (~m). The noble metal particles may be commercially obtained in finely divided form, or may be ground to the required particle size in suitable devices.
The noble metal halide component of the composition is a critical ingredient. Elemental metallic particles of noble metals, such as gold or silver, will not perform the same improved results. It is not clear at present why the noble metal halide component alone or in combination with a noble based metal component reacts with the dental porcelain or with a dental metal part so as to form a clinically unbreakable bond upon sintering which is believed to be chemical in nature whereas metallic noble metal particles will not. The noble metal halide, preferably, may be in the form of finely divided particles. I'he noble metal halides are commercially available in powder or cristalline form and in a i 1, - ' ' ~3~7~6 particle size range within or below the desired range for the noble based metal component; e.g. a particle size in the range of 1 to 60 microns. For example, gold chloride is commercially available as HAuC14 and may be directly used in this form. Although the noble metal halide may also be used in amounts of 100%, preferably a noble metal should also be used, especially gold or an alloy containing a high percentage of gold because of the desire to have a substantial background gold colour underneath the porcelain overlay.
The bonding material may be used with or without suitable dispersants and/or binders. Preferably, the bonding material according to the invention is used together with a binder so that it may be readily and controllably applied to the metal surface such as by brushing, painting, dipping or spraying. The binder or carrying vehicle may be preferably removed under the influence of heat, i.e. it should preferably burn~o~r vol~tilize in the sintering process without a residue. The same applies to dispersants for which the known water detergents may be used. Preferred binders are organic substances with adhesive properties which may also be diluted with suitable solvents. If no dispersant or binder is used, the bonding material may be applied to the metal surface ~ in a suitable manner, e.g. by applying the powder or an a~ueous or organic dispersion.
The usual dental metals or dental alloys may be used for the metal substrate. The metal substrate is, preferably, a noble metal substrate. Generally~ the composition of the metal substrate may correspond to the composition of the finely divided noble metal component, e.g. the metal substrate is preferably at least predominantly composed of one or several of the noble metals gold, silver, platimum or palladiu~.

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After applying the bonding material, optionally together with a dispersant and~or binder, onto a dental metal part the bonding material is sintered to the applied unit (s) at a temperature range between about 870 to 1080C; temperatures below or above this range may also be applied which, among others, depends upon the composition of the bonding agent or the substrate. An optimum temperature range is between about 1010C
and about 1040C. The bonding agent is usually sintered for about 1 to 25 min., preferably 5-25 min. The sintering temperature also depends upon the type of the noble metal halide used, i.e. the noble metal halide may wet the noble metal substrate even at temperatures below about 870C.
In preparing a crown, bridge or denture, it is frequently preferred to select a sintering temperature which will only cause the bonding agent to form a coating of irregularly shaped particles on the metal substrate.
An optimum temperature range for this purpose is between about 980C and about 1024C. Thereafter, the dental porcelain is fired onto the thus treated surface. The firing temperature for dental porcelain generally depends upon its composition, but generally falls within a range of about 870C to about 1000C.
Preferred dental metal parts onto which the bonding material according to the invention may be fired include, for example, noble metal foils, preferably platinum foils. Several identical or different layers of bonding material may be fired onto the dental metal part; i.e.
the layers of bonding material have the same or different composition.
After the method according to the invention has been performed, the dental po~celain is fused to the noble metal substrate to form an unbreakable bond. The sintered bonded material is believed to chemically interact with the dental porcelain in forming the unbreakable bond. It is not quite clear whether the noble metal chloride or fluoride itself --'` ~

' ' ' :-~3~7~6 decomposes or escapes during sintering. ~lowever, it is clear that the noble metal halides participate in the formation of an unbreakable bond.
An unbreakable bond is defined for purposes of the present invention as a bonded joint which does not under clinical conditions permit separation of the members at the bonded interface. This is simply determined by applying a sufficient impact force in a direction normal to the composite structure until the structure breaks and then visually inspecting the broken structure to see if separation occurred at the interface between the members.
For dental restoration, porcelain-coated cast metal crowns are mainly used. The relatively thick metal substructure is made by providing a wax impression from the prepared tooth; this impression is embedded in an embedding composition, the wax is burned out, and metal is cast into the cavity. Thereafter, the dental porcelain is coated onto the metal substructure in layers, and fired. The metal used is preferably a noble metal or a noble metal alloy in which the amount of gold predominates.
The thickness of the cast metal substructure is within the range of 0.2 to 0.5 mm; the substructure is relatively expensive due to the noble metals used. Furthermore, a bulky metal substrate does not leave sufficient space for the dental porcelain coating.
Therefore, a jacket crown is to be preferred. It is superior to all other restorations in an esthetic sense, and cannot be distin-guished from a natural tooth. However, in most cases, it can be used only for anteriors where esthetic considerations are predominant. The limited use is due to the insufficient strength of the dental porcelain used. A jacket crown is usually made by adapting a platinum foil to the prepared tooth stump, and the foil is then removed, coated with porcelain .

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:, , - ' ~ ' - , ' ` , -Z~6 and fired. Then, the platinum foil is removed again, and the jacket crown ls cemented in place. According to German Offenlegungsschrift 25 31 113, the platinum foil does not have to be removed, but remains in place to reinforce the dental porcelain. The metal oxide layer, e.g.
the tin oxide layer is to bond the dental porcelain with the platimun foil.
The bonding material of the present invention can be applied to a noble metal substrate e.g. Eor the purpose of making crowns. The method of the present invention naturally includes the use of noble metal foils, especially platinum foils, as noble metal substrate. The thickness of the model and the composition of the noble metal substrate depend on what is to be made, e.g. crowns, jacket crowns or other dental restorations.
By applying the bonding material of the present invention, e.g. to a platinum foil, firing the bonding material and subsequently applying and firing dental porcelain in layers, the bonding material and method according to the present invention provide a re-enforced jacket crown which has a substantially higher strength than that of German Offenlegungsschrift 25 31 113.
The noble metal substrate can be coated with one layer of the bonding material of the present invention to be fired, but several layers may also be applied and fired onto the substrate. If a noble metal foil, especially a platinum foil, is used as the noble metal substrate, at least one layer is fired on, preferably, however, two layers, and even a plurality of layers may be fired on. The total thickness of the layers will depend on how the platinum foil can be handled. If the layer of the bonding material is too thick, the foil will become too stiff so that it is difficult to adapt it to the tooth ~3~7~6 stump. Preferably, for example, the bonding material is applied as a thin film in about the same thickness range as that of the metal foil, thin platinum may have a thickness varying from 0.0015 mm to 0,05 mm.
The bonding material of the present invention may be applied and fired onto a platinum foil before the foil is adapted to the prepared stump. Thus, ~he platinum foil may be sold together with one or several layers of the fired bonding material. This also applies for other suitable noble metal substrate.
If several layers are used, they do not need to be identical.
One layer may consist of a bonding material comprising 1 to 100% noble metal halides and 0 to 99% noble metals whereas the other layers may be the same or different from the first layers.
The bonding material may be sintered simultaneously with the firing of the porcelain; however this is not preferred.
Thus in accordance with the present invention a jacket crown may be formed as a composite body having an inner structure composed of a thin foil layer of material conforming in shape to the prepared tooth, ~ith at least one intermediate layer of a predetermined material composi-tion surrounding the foil core and fused to one face thereof at a pre-~0 determined elevated temperature and a relatively thick outer coating ofdental ceramic material surrounding said inner structure and being bonded to the foil layer through the intermediate layer. The intermediate layer between the porcelain coating and the foil layer is formed from a finely divided particle composition comprising of from about 1 ~o 100% of a noble metal halide and from zero to 99% of particles of a noble metal component.
In summary, the present invention is concerned ~ith the formu-lation of a clinlcally unbreakable composite~body between a ceramic .
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member and a noble based metal member or between two such metal members by the incorporation of a bonding material between the members to be joined. In accordance with the present invention the bonding material may initially be deposited upon the surface of either one or both of the members to be joined to form a relatively uniform layer which is heated to a predetermined temperature until the bonding material is sintered whereupon the two members are brought together, with the substantially sintered bonding material therebetween and the assembly baked in an oven at a second predetermined temperature sufficient to cause the bonding material to react at the interface with the overlaid member. The pre-liminary sintering step is preferred but not essential particularly in the case of two metal members. However, in the latter case the second heating step should be at a sufficiently elevated temperature to wet the bonding material to both members. In preparing fixed prosthetic dental devices the porcelain ceramic is preferably applied in layers to the metal framework surface following the steps of applying and sintering the bonding material to the metal framework. The bonding material may also be applied to a ceramic member and/or to the metal member separately before j~ining the two.
In drawings which illustrate an embodiment of the present invention, Figure 1 a foil in the process of being wrapped around a stump model, Figure 2 shows a foil wrapped stump model, and Figure 3 shows a foil substrate.
The`invention is further illustrated by the ~ollo~ing examples.
All percentages refer to the weight.

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Example 1 A bonding material having the following composition is applied to a metal substructure (thin noble metal, 100% Pt):
~a) 1.4% by weight of a noble metal halide consisting of AgCl in powder form and ~b) 98.6% by weight of a noble based metal component consisting of finely divided (alloy) particles (between 5 and 10 microns (~m)) having the following composition: 97% Au, 0.6% Ag, 0.4% Pt and 2% Cu, Fe, Cr, Cd.
The bonding agent is fired onto the platinum foil at 1024C
for 3 minutes. Thereafter, a layer of a commercial dental porcelain ~manufactured by Ceramco) is applied and fired at 969C. The resulting composite structure is clinically unbreakable.
Corresponding tests were carried out with other dental porcelains with comparable results.
Example 2 The procedure of example 1 was repeated with the exception that the metal substructure was changed as follows:
~1) 87.5% Au, 4.5% Pt, 6% Pd, balance trace elements;
~2) 52% Au, 38% Pd, 4% Zn, balance trace elements;
~3) 60% Ag, 40% Pd.
In each case the results obtained are comparable to those of example 1.
Example 3 The procedure of example 1 was repeated with the exception that the bonding material consisted of (a) 93% AgCl and ~b~ 7% of the same noble metal component as in example 1. Comparable results were obtained.

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Example 4 The procedure of example 1 was repeated with the exception that the bonding material consisted of (a) 50% AgCl and (b) 50% of the same noble metal component as in example 1. Comparable results were obtained.
Example 5 The procedure of example 1 was repeated with the exception that the bonding material consisted of (a) 7% AgF and (b) 93% of a noble metal component consisting of Au. The resulting composite structure is clinically unbreakable.
Example 6 The procedure of example 1 was repeated with the exception that only PtC12, i.e. no noble metal component was used. Comparable results were obtained.
Example 7 The procedure of example 1 was repeated with the exception that the bonding material consisted of (a) 10% PtC12 and (b) 90% of a noble metal component consisting of Au. Comparable results were obtained.
Example 8 ~ The procedure of example 1 was followed with the exception that only HAuC14, i.e. no noble metal component was used as bonding material. Comparable results were obtained.
Example 9 The procedure of example 1 was repeated with the exception that the bonding material consisted of (a) 10% ~AuC14 and (b) 90% of a noble metal component consisting of Au. Comparable results were obtained.
Example 10 The procedure of example 1 was repeated with the exception 3,~3'5~

that the bonding material consisted of (a) 5% AgC12 and 5% PtC12 and (b) 90% of a noblè metal component consisting of Au were used. Comparable results were obtained.
Example 11 The procedure of example 1 was repeated with the exception that the bonding material consisted of (a) 10% HAuC14 and 5% PtC12 and (b) 80% of a noble metal component consisting of Au. The balance (5%) consisted of an organic binder. Comparable results were obtained.
Example 12 A stump model 18 is made from an impression of the prepared tooth. As shown in Figure 1, a platinum foil 10 is closely wrapped around the stump 18, forming overlapping ends 20 which are folded as shown in Figure 2. The foil should extend beyond the gingival margin 26 and form a kind of seam 28; see Figure 3. By means of an instrument or by hand, pressure is applied to foil 10 so as to press it closely to stump 18. Subsequently, it is drawn from the stump and provided with a noble metal substrate as shown in Figure 3.
The bonding material according to example 8 is applied to this metal substrate and fired at 970C for 5 minutes. Thereafter, several ~ dental porcelain layers are applied and fired onto the substrate in a known manner.
In order to show the strength of the finished crown, the crown is fixed to a metal stump, and a metal pin is contacted with the incisal boundary of the crown. A metal cylinder weighing 100 g is held and dropped from a distance of 20 cm over the metal pin. No significant damage of the crown could be detected. If the distance of the metal cylinder is increased to~40 cm, the porcelain only breaks in a limited area~

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For comparison, the same test is performed with a crown that has been made without the bonding material according to the invention.
The 100 g weight dropped from a height of 20 cm causes large d~ntal porcelain particles to split off.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A bonding material suitable for bonding a dental metal part to dental porcelain or to another dental metal part for making dental restorat-ions characterized in that said bonding material comprises 1 to 99.9% by weight of at least one noble metal halide and 0.1 to 99% by weight of a finely divided noble metal component.

2. A bonding material according to claim 1 characterized in that said noble metal halide is selected from the group consisting of noble metal chlorides, noble metal fluorides and mixtures thereof.

3. A bonding material according to claim 1 characterized in that said noble metal halide is selected from the group consisting of silver chloride, silver fluoride, gold chloride, gold fluoride and mixtures thereof.

4. A bonding material according to claim 1 characterized in that said noble metal halide comprises finely divided particles thereof.

5. A bonding material according to claim 3 characterized in that said noble metal halide comprises finely divided particles thereof.

6. A bonding material according to either of claims 1 or 2 characterized in that said noble metal component contains or consists of gold, platinum, silver, palladium and mixtures thereof.

7. A bonding material according to claim 3 characterized in that said noble metal component contains or consists of gold, platinum, silver, palladium and mixtures thereof.

8. A bonding material according to either of claims 4 or 5 characterized in that said noble metal component contains or consists of gold, platinum, silver, palladium and mixtures thereof.

9. A bonding material according to either of claims 1 or 2 characterized in that said noble metal component comprises at least 50% by weight of gold, 0% to 45% by weight of a metal selected from the group consisting of silver, platinum, palladium, rhodium and mixtures thereof and 0% to 5% by weight of a base metal selected from the group consisting of copper, zinc, iron, tin, cadmium, manganese, germanium magnesium, cobalt, nickel and mixtures thereof.

10. A bonding material according to claim 3 characterized in that said noble metal component comprises at least 50% by weight of gold, 0% to 45%
by weight of a metal selected from the group consisting of silver, platinum, palladium, rhodium and mixtures thereof, and 0% to 5% by weight of a base metal selected from the group consisting of copper, zinc, iron, tin, cadmium, manganese, germanium, magnesium, cobalt nickel and mixtures thereof.

11. A bonding material according to claim 10 characterized in that said noble metal halide comprises finely divided particles thereof.

12. A bonding material according to either of claims 1 or 2 characterized in that said bonding material additionally comprises a material selected from the group consisting of dispersants, binders and mixtures thereof.

13. A bonding material according to claim 11 characterized in that said bonding material additionally comprises a material selected from the group consisting of dispersants, binders and mixtures thereof.

14. A bonding material according to either of claims 1 or 2 characterized in that said bonding material additionally comprises a binder which is removable under the influence of heat.

15. A bonding material according to claim 11 characterized in that said bonding material additionally comprises a binder which is removable under the influence of heat.

16. A bonding material according to either of claims 4 or 5 characterized in that the particle size of the noble metal component is in the range of about 1 to about 60 microns.

17. A bonding material according to claim 11 characterized in that the particle size of the noble metal component is in the range of about l to about 60 microns

18. A bonding material according to claim 17 characterized in that the particle size of the noble metal halide is in the range of about l to about 60 microns.

19. A bonding material according to claim 1 wherein said noble metal halide is HAuCl4.

20. A method for preparing a pretreated dental metal part suitable for making a dental restoration by bonding said pretreated dental metal part to dental porcelain or to another dental metal part characterized in that a suitable metal substrate on which a bonding material has been applied is subjected to a high temperature to sinter or fire said bonding material thereon, said bonding material comprising 1% to 100% by weight of at least one noble metal halide and 0% to 99% by weight of a finely divided noble metal component.

21. A method according to claim 20 characterized in that said bonding material comprises 1% to 99.9% by weight of at least one noble metal halide and 0.1% to 99% by weight of said finely divided noble metal component.

22. A method according to claim 20 characterized in that said metal substrate is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

23. A method according to claim 21 characterized in that said metal substrate is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum and mixtures thereof.

24. A method according to claim 20 characterized in that said noble metal halide is selected from the group consisting of noble metal chlorides, noble metal fluorides and mixtures thereof.

25. A method according to claim 23 characterized in that said noble metal halide is selected from the group consisting of noble metal chlorides, noble metal fluorides and mixtures thereof.

26. A method according to claim 20 characterized in that said noble metal halide is selected from the group consisting of silver, chloride, silver fluoride, gold chloride, gold fluoride and mixtures thereof.

27. A method according to claim 23 characterized in that said noble metal halide is selected from the group consisting of silver chloride, silver fluoride, gold chloride, gold fluoride and mixtures thereof.

28. A method according to claim 20 characterized in that said noble metal component is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

29. A method according to claim 23 characterized in that said noble metal component is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

30. A method according to claim 20 characterized in that said;

noble metal component comprises at least 50% by weight of gold, 0% to 45% by weight of a metal selected from the group consisting of silver, platinum, palladium, rhodium and mixtures thereof, and 0% to 5% by weight of a base metal selected from the group consisting of copper, zinc, iron, tin, cadmium, manganese, germinium, magnesium, cobalt, nickel and mixtures thereof.

31. A method according to claim 23 characterized in that said noble metal component comprises at least 50% by weight of gold, 0% to 45% by weight of a metal selected from the group consisting of silver, platinum, palladium, rhodium and mixtures thereof, and 0% to 5% by weight of a base metal selected from the group consisting of copper, zinc, iron, tin, cadmium, magnesium, cobalt, nickel and mixtures thereof.

32. A method according to claim 20 characterized in that said bonding material additionally comprises a material selected from the group consisting of dispersants, binders and mixtures thereof.

33. A method according to claim 23 characterized in that said bonding material additionally comprises a material selected from the group consisting of dispersants, binders and mixtures thereof.

34. A method according to claim 20 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon at a temperature in the range of from about 870°C to about 1080°C.

35. A method according to claim 23 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon at a temperature in the range of from about 870°C to about 1080°C.

36. A method according to claim 20 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon for a time period in the range of from about 1 minute to 75 minutes.

37. A method according to claim 23 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon for a time period in the range of from about 1 minute to 25 minutes.

38. A method according to claim 20 characterized in that the noble metal halide comprises finely divided particles thereof.

39. A method according to claim 23 characterized in that the noble metal halide comprises finely divided particles thereof.

40. A method according to claim 20 characterized in that the noble metal component has a particle size in the range of about 1 to about 60 microns.

41. A method according to claim 23 characterized in that the noble metal component has a particle size in the range of about 1 to about 60 microns.

42. A method according to claim 20 characterized in that the said metal substrate is a foil of a noble metal.

43, A method according to claim 23 characterized in that said metal substrate is a foil of a noble metal.

44, A method according to claim 20 characterized in that said metal substrate is a foil of platinum.

45. A method according to claim 23 characterized in that said metal substrate is a foil of platinum.

46. A method according to claim 20 characterized in that one or more layers of bonding material are sintered or fired on said metal substrate said layers of bonding material being of the same or different composition.

47. A method according to claim 23 characterized in that one or more layers of bonding material are sintered or fired on said metal substrate, said layers of bonding material being of the same or different composition.

48. A method according to claim 26 characterized in that said noble metal component is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

49. A method according to claim 27 characterized in that said noble metal component is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

50. A method according to claim 26 characterized in that said metal substrate is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

51. A method according to claim 50 characterized in that said noble metal component comprises at least 50 % by weight of gold, 0°% to 45% by weight of a metal selected from the group consisting of silver, platinum, palladium, rhodium and mixtures thereof and 0% to 5% by weight of a base metal selected from the group consisting of copper, zinc, iron, tin, cadmium, manganese, germanium, magnesium, cobalt, nickel and mixtures thereof.

52. A method according to claim 51 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon at a temperature in the range of from about 870°C to 1080°C.

53. A method according to claim 52 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon for a time period in the range of from about 1 minute to about 25 minutes.

54. A method according to claim 53 characterized in that the noble metal component has a particle size in the range of 1 to 60 microns.

55. A method according to claim 54 characterized in that the noble metal halide comprises finely divided particles having a particle size in the range of 1 to 60 microns.

56. A method according to claim 55 characterized in that said metal substrate is a foil of platinum.

57. A method according to claim 51 characterized in that the bonding material additionally comprises a material selected from the group consisting of dispersants, binders and mixtures thereof.

58. A method according to either of claims 51, 52 or 53 characterized in that said bonding material comprises 1% to 99.9% by weight of said noble metal halide and 0.1% to 99% by weight of said finely divided noble metal component.

59. A method according to either of claims 54, 55 or 56 characterized in that said bonding material comprises 1% to 99.9% by weight of said noble metal halide and 0.1% to 99% by weight of said finely divided noble metal component.

60. A method according to claim 57 characterized in that said bonding material comprises 1% to 99.9% by weight of said noble metal halide and 0.1% to 99% by weight of said finely divided noble metal component.

61. A method for making a dental restoration by bonding a dental metal part to dental porcelain characterized by the steps of:
(a) applying a bonding material to a suitable metal substrate, said bonding material thereafter being sintered or fired thereon at a high temperature, said bonding material comprising 1% to 100% by weight of at least one noble metal halide and 0%
to 99% by weight of a finely divided noble metal component and, (b) applying dental porcelain over said sintered or fired bonding material and firing said dental porcelain thereon.

62. A method according to claim 61 characterized in that said bonding material comprises 1% to 99.9% by weight of at least one noble metal halide and 0.1% to 99% by weight of said finely divided noble metal component.

63. A method according to claim 61 characterized in that said metal substrate is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

64. A method according to claim 62 characterized in that said metal substrate is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

65. A method according to claim 61 characterized in that said noble metal halide is selected from the group consisting of noble metal chlorides, noble metal fluorides and mixtures thereof.

66. A method according to claim 64 characterized in that said noble metal halide is selected from the group consisting of noble metal chlorides, noble metal fluorides and mixtures thereof.

67. A method according to claim 61 characterized in that said noble metal halide is selected from the group consisting of silver chloride, silver fluoride, gold chloride, gold fluoride and mixtures thereof .

68. A method according to claim 64 characterized in that said noble metal halide is selected from the group consisting of silver chloride, silver fluoride, gold chloride, gold fluoride and mixtures thereof.

69. A method according to claim 61 characterized in that said noble metal component is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

70. A method according to claim 64 characterized in that said noble metal component is at least predominantly composed of a noble metal selected from the group consisting of gold, silver, platinum, palladium and mixtures thereof.

71. A method according to claim 61 characterized in that said noble metal component comprises at least 50% by weight of gold, 0% to 45% by weight of a metal selected from the group consisting of silver, platinum palladium, rhodium and mixtures thereof and 0% to 5% of a base metal selected from the group consisting of copper, zinc, iron, tin, cadmium, manganese, germanium, magnesium, cobalt, nickel and mixtures thereof.

72. A method according to claim 64 characterized in that said noble metal component comprises at least 50% by weight of gold, 0% to 45% by weight of a metal selected from the group consisting of silver, platinum, palladium, rhodium and mixtures thereof and 0% to 5% by weight of a base metal selected from the group consisting of copper, zinc, iron, tin, cadmium, manganese, germanium, magnesium, cobalt, nickel and mixtures thereof.

73. A method according to claim 61 characterized in that said bonding material additionally comprises a material selected from the group consisting of dispersants, binders and mixtures thereof.

74. A method according to claim 64 characterized in that said bonding material additionally comprises a material selected from the group consisting of dispersants, binders and mixtures thereof.

75. A method according to claim 61 characterized in that the bonding material applied to the metal substrate is sintered or fixed thereon at a temperature in the range of from about 870°C to about 1080°C

76. A method according to claim 64 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon at a temperature in the range of from about 870°C to about 1080°C.

77. A method according to claim 61 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon for a time period in the range of from about 1 minute to about 25 minutes.

78. A method according to claim 61 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon for a time period in the range of from about 1 minute to about 25 minutes.

79. A method according to claim 61 characterized in that the noble metal halide comprises finely divided particles thereof.

80. A method according to claim 64 characterized in that the noble metal halide comprises finely divided particles thereof.

81. A method according to claim 61 characterized in that the noble metal component has a particle size in the range of about 1 to about 60 microns.

82. A method according to claim 64 characterized in that the noble metal component has a particle size in the range of about 1 to about 60 microns.

83. A method according to claim 61 characterized in that said metal substrate is a foil of a noble metal.

84. A method according to claim 64 characterized in that said metal substrate is a foil of a noble metal.

85. A method according to claim 61 characterized in that said metal substrate is a foil of platinum.

86. A method according to claim 64 characterized in that said metal substrate is a foil of platinum.

87. A method according to claim 61 characterized in that one or more layers of bonding material are sintered or fired on said metal substrate, said layers of bonding material being of the same or different composition.

88. A method according to claim 64 characterized in that one or more layers of bonding material are sintered or fired on said metal substrate, said layers of bonding material being of the same or different composition.

89. A method according to claim 67 characterized in that said noble metal component is at least predominantly composed of a noble metal selected from the class consisting of gold, silver, platinum, palladium and mixtures thereof.

90. A method according to claim 68 characterized in that said noble metal component is at least predominantly composed of noble metal selected from the group consisting of gold silver, platinum, palladium and mixtures thereof.

91. A method according to claim 67 characterized in that said metal substrate is at least predominantly composed of a noble metal selected from the class consisting of gold; silver, platinum, palladium and mixtures thereof.

92. A method according to claim 91 characterized in that said noble metal component comprises at least 50% by weight of gold, 0% to 45% by weight of a metal selected from the group consisting of silver, platinum, palladium, rhodium and mixtures thereof, and 0% to 5% by weight of a base metal selected from the group consisting of copper, zinc, iron, tin, cadmium, manganese, germanium, magnesium, cobalt, nickel and mixtures thereof.

93. A method according to claim 92 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon at a temperature in the range of from about 870°C to 1080°C.

94. A method according to claim 93 characterized in that the bonding material applied to the metal substrate is sintered or fired thereon for a time period in the range of from about l minute to 25 minutes.

95. A method according to claim 94 characterized in that the noble metal component has a particle size in the range of from l to 60 microns.

96. A method according to claim 95 characterized in that the noble metal halide comprises finely divided particles having a particle size in the range of about I to about 60 microns.

97. A method according to claim 96 characterized in that said metal substrate is a foil of platinum.

98. A method according to claim 92 characterized in that the bonding material additionally comprises a material selected from the group consisting of dispersants binders and mixtures thereof.

99. A method according to either of claims 92 93 or 94 char-acterized in that said bonding material comprises 1% to 99.9% by weight of said noble metal halide and 0.1% to 99% by weight of said finely divided noble metal component.

100. A method according to either of claims 95 , 96 or 97 characterized in that said bonding material comprises 1% to 99.9% by weight of said noble metal halide and 0.1% to 99% by weight of said finely divided noble metal component.