WO2003013386A1 - Method for the production of prosthetic shaped parts for dentistry - Google Patents

Abstract

The invention relates to a method for the production of prosthetic shaped parts (10b) for dentistry, wherein a pattern of a shaped part (10b) is produced using a molding technique; the pattern is coated with at least one metal layer (12, 20) in at least one coating step; the pattern is then chemically dissolved, whereby a formed body remains, said formed body then being fitted with a lining (18) consisting of ceramic or plastic material and whereby the at least one metal layer (12) is then optionally removed after the lining (18) has been produced. Alternatively, a sandwich consisting of several layers can also be produced. The inventive method makes it possible to produce high-quality prosthetic shaped parts, the properties of which can be customized to the desired application. The metal layer (12) can be used as a combustion-resistant supporting frame in the production of a ceramic lining.

Description

 Process for the production of prosthetic molded parts for the

dental field

The invention relates to a method for producing prosthetic molded parts for the dental field, in which a model of a molded part is produced by an impression technique, the model is coated with at least one metal layer in at least one coating step in order to produce a molded part after the model has been removed is provided with a ceramic or plastic cover.

Prosthetic molded parts for the dental field have been produced in casting technology since the last century. Here, a wax model of the prosthetic molded part is first created after an impression, which is then cast around with a ceramic mass, which is then fired. When firing, the ceramic mass creates a solid shape with a cavity that corresponds to the wax model, while the wax is completely expelled during firing. The so The mold cavity can now be poured out with a suitable casting alloy in order to produce a casting which corresponds to the shape of the impression taken by the patient.

If such a prosthetic molded part is to be used in the visible area, it must also be covered with a ceramic or plastic coating in order to achieve a natural appearance of the dentures produced in this way.

Although the casting technique is still the most widely used molding process for historical reasons, the casting technique has considerable disadvantages. In this way, pores and cavities as well as other defects occur repeatedly in castings, which have an adverse effect on the quality of the prosthetic molded parts produced. The accuracy of fit of the molded parts produced leaves much to be desired. Finally, the biocompatibility of cast alloys is not good because a number of additional alloy components, such as Ag, Pd, Cu, Co, etc., can sometimes lead to allergies or otherwise contribute to poor biocompatibility. Cast alloys are also often too soft.

For this reason, so-called electroforming has recently been developed, with which a precious metal supporting structure, which consists of gold or a gold alloy, is galvanically produced. This supporting structure is then veneered with ceramic or plastic, which creates aesthetically particularly appealing dentures that are deceptively similar to the appearance of a natural tooth, since the base body made of gold shimmers through the partially translucent ceramic. Such a galvanoforming method is known from EP 0990423 A1, for example, with which fireproof dental prosthetic parts that can be veneered with ceramic can be produced. After that, a so-called master model is first used to make a duplicate of the tooth stump in question, for example using plaster. The duplicate tooth stump which is connected as the cathode during the deposition is then provided with a feed in the form of a copper wire and made conductive by means of conductive silver lacquer. Gold is then deposited on the electrode stump in a galvanizing bath, resulting in a metal molding made of gold which can be veneered with ceramic material after removal of the tooth duplicate stump.

Although a prosthetic molded part produced in this way is characterized by high durability and a natural appearance, the production is relatively expensive, in particular because of the relatively high gold content with a thickness of approximately 150-300 μm.

The invention is therefore based on the object of specifying a method for producing prosthetic molded parts for the dental field with which high-quality molded parts can be produced in a relatively inexpensive manner.

According to the invention, this object is achieved in a method according to the type mentioned at the outset by removing the at least one metal layer after the veneer has been produced.

The object of the invention is completely achieved in this way. Because the at least one metal layer, which serves as a base layer for the production of the ceramic or plastic veneer during the production of the veneer, is removed again after the veneer has been produced, it is also possible to use non-precious metal layers that are less biocompatible than metal layers to use.

Alternatively, the object of the invention is achieved in a method according to the type mentioned at the outset in that at least one further layer is deposited on the metal layer or the model by an electrochemical deposition method or a physical deposition method under vacuum or protective gas.

The object of the invention is also achieved in this way.

Since at least one further layer is deposited on the metal layer, it is possible in this way to form the molding as a sandwich, the top layer of which is specially adapted to the properties of the veneer. The layer thickness of the uppermost layer can thus be significantly reduced and a layer which is particularly well adapted to the veneer with regard to the properties can be used for this purpose, while the layer below it can serve, for example, as a supporting structure for the subsequent application of the veneer. It is thus possible, for example, to combine a stable non-noble metal layer as an underlayer with a thin noble metal layer, in particular with a thin gold layer or gold-containing layer, in order to achieve particularly good aesthetics and biocompatibility at low cost. If subsequent veneering with a ceramic material takes place, the molding can be sufficiently temperature-resistant to ensure good mechanical stability during the firing process of the ceramic.

In principle, it is also possible to apply a layer containing noble metal (hereinafter referred to as a noble metal layer), which serves as a base layer or bond layer in the later production of the veneer from ceramic or plastic. The precious metal layer can then be chemically dissolved again, e.g. a layer of gold could be dissolved with the help of aqua regia and the gold recovered could be used again.

At least one metal layer is preferably applied by electrodeposition, for which purpose the model is first provided with an electrically conductive coating and contacted with an electrical lead.

In principle, however, other physical or chemical methods are also conceivable in order to deposit the layers on the model. This includes, for example, deposition by PVD or CVD. For example, the top layer could consist of a thin titanium nitride layer that is deposited on an underlying base layer.

In this way, a gold-colored ceramic layer can be produced, which enables a good bond to an applied ceramic coating. Galvanic deposition has the particular advantage of high precision, since the galvanically deposited layer can be precisely adjusted in its layer thickness depending on the surface of the material to be coated, a uniform coating thickness can be guaranteed and an extraordinarily homogeneous structure of the metal molding produced in this way can be achieved. Larger layer thicknesses can also be produced galvanically in the desired range, which is not possible with CVD or PVD.

The veneer is preferably made of ceramic, as a result of which long-term stable prosthetic molded parts can be produced which have high stability. In this case, the molding is designed as a fireproof support body for the production of the ceramic veneer.

In principle, however, the veneer can of course also be produced from plastic, in which case less temperature-stable metals can also be used for the production of the metal layer, such as Silver, copper and tin or their alloys.

As already mentioned, at least one noble metal layer and / or at least one metal layer made of a base metal (base metal layer) can be applied.

While it is fundamentally possible, for example, to remove the noble metal layer again after the veneer has been produced, a particularly advantageous embodiment results in particular when the noble metal layer has only a thin layer thickness, preferably in the range from about 1 to 50 μm, in particular in the range from approximately 5 to 15 μm, is used and remains in the prosthetic molded part.

In this case, the noble metal layer does not serve as a base layer in the production of the ceramic veneer or the plastic veneer, however, the special aesthetic advantages of the noble metal layer are used, since a thin noble metal layer is also sufficient to prevent shimmering through a partially translucent ceramic or a partially transparent to ensure lucent plastic and thus to achieve a particularly natural appearance. Equally, the particularly good biocompatibility of the precious metal layer and the advantageous cementability when inserting the prosthetic molded part are used. In this case, the load-bearing capacity of the prosthetic molded part is not guaranteed by the noble metal layer during the manufacture of the veneer, but preferably by a further non-noble metal layer applied to the noble metal layer. The base metal layer can then be produced with a sufficient layer thickness from a suitable metal in order to ensure good mechanical stability, especially when the ceramic veneer is fired. Since the base metal layer is removed again after the veneer has been produced, for example by dissolving it chemically, no consideration needs to be given to the biocompatibility of the alloy used.

Alternatively, a very corrosion-resistant non-precious metal layer, for example made of a CrCo alloy or a CrMoCo alloy, can be used as the base layer, which will not be removed later and to which a cover layer made of gold, for example, is applied. If the possible usable noble metals and non-noble metals are discussed in more detail below, then for the sake of simplification, when the term "alloy" is used, the pure metal is also to be understood by this, for example the term "cobalt alloy" should also be used include the metal cobalt.

When producing the thin precious metal layers mentioned above, the use of layers of gold alloys is particularly advantageous because of their known advantageous aesthetic properties and because of their particularly good biocompatibility.

In addition, according to a further variant of the invention, it is possible to produce a plurality of non-noble metal layers one above the other and, if appropriate, to remove one or more of them after the veneer has been produced.

Such a sandwich structure is particularly advantageous if, for example, no precious metal is to be used for a particularly cost-effective variant, and e.g. a cobalt alloy or a particularly corrosion-resistant chrome / cobalt alloy is to be used, but a particularly dimensionally stable supporting structure, for example made of a nickel alloy, is to be used to produce a ceramic veneer.

A less biocompatible layer of, for example, a nickel alloy, which, however, enables particularly good dimensional stability during the firing process, is preferably removed again after the ceramic veneer has been produced. The properties of the various metal layers can be tailored in the manner described above, on the one hand to ensure good dimensional stability in the production of a ceramic veneer or a veneer made of plastic and on the other hand to achieve an aesthetically particularly advantageous molded part with high durability and good biocompatibility.

Depending on which property is particularly important for the respective application, such as optimized biocompatibility and particularly advantageous aesthetics, e.g. the focus is on the use of a thin layer of precious metal.

If, on the other hand, the focus is on a particularly cost-effective production with somewhat reduced requirements for biocompatibility or durability and aesthetics, only a metal layer, e.g. be preferred from a nickel alloy as a supporting structure for the production of the veneer, which is then detached again after the veneer has been produced, so as to produce an all-ceramic in a particularly cost-effective manner.

In addition, as mentioned above, further variants are conceivable, for example the use of a particularly corrosion-resistant base metal layer, e.g. a CrCo alloy and another metal layer as a supporting structure, which can be removed again after the veneer has been made.

In principle, all known precious metal alloys that have been tried and tested in the dental field can be considered as precious metal layers. This includes in particular alloys based on gold sis, with proportions of silver, platinum, palladium and possibly other conventional alloy components, such as copper, tin, zinc, indium, galium, iridium, rhodium, etc. Silver alloys are also suitable.

The non-ferrous metals in particular from the series of non-ferrous metals (NEM) are the alloys of the metals nickel, chromium, cobalt, molybdenum, which are used for deiital materials as NiCr alloys, Ni-based alloys, CrCoMo alloys, CrCo alloys, Co alloys are used. The use of iron alloys is also possible.

Copper, antimony, selenium or the like can be used as further alloy or layer components, but ceramic disper gates with particle sizes between 5 nm and 5 μm can also be present, the layer thickness of the individual metal layers between 0.01 μm and approximately 300 μm can be.

It goes without saying that the features of the invention mentioned above and those yet to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own without departing from the scope of the invention.

Further features and advantages of the invention result from the following description of preferred exemplary embodiments and reference to the drawing. Show it: Fig. La shows a cross section of a first embodiment of a prosthetic molded part according to the invention using the example of a crown;

Fig. Lb a modification of the embodiment of FIG la.

FIG. 1c shows a further modification of the embodiment according to FIG. and

2 shows a perspective view of a tooth stump model which is provided with an electrical lead in order to galvanically deposit a metal layer on the surface of the tooth stump model in a subsequent deposition process.

The method according to the invention is suitable both for the production of prosthetic molded parts with a metal substructure and ceramic veneering or plastic veneer, as well as for the production of molded parts made of all-ceramic or all-plastic, without any metal content.

In the case of the different process variants, which are selected depending on the intended use, the manufacturing process in all cases initially involves the production of one or more metal layers on a model, which is then provided with a ceramic or plastic veneer. After the veneer has been produced, if desired, at least one of the metal layers can then be removed again, which is preferably done by chemical dissolution. Starting from a so-called master model, a duplicate model is first produced using an impression technique, for example using plaster. The duplicate model, which is shown schematically in FIG. 2 and is designated overall by the number 30, is provided with an electrical feed line 34. For this purpose, a hole is first drilled, which is indicated schematically by the number 32, and the electrical feed line 34 is glued in, for example in the form of a copper wire. The duplicate model 30 is then provided on its surface to be coated with an electrically conductive layer 36, for example by applying conductive silver lacquer with a layer thickness of approximately 0.5 mm, a connection being made up to the electrical supply line 34.

The surface to be coated of the electroplated die thus produced is estimated or measured in order to determine the amount of material to be coated which has to be introduced into an electroplating bath in order to produce a certain layer thickness when deposited on the electroplated stump.

The electroplating die is electroplated in a suitable electroplating bath, for example using the electroplating device which is sold by the applicant under the name GAMMAT and in which, depending on the embodiment, one to sixteen parts can be coated at the same time.

The electroplating bath used contains the metal or metals to be deposited in a suitable concentration in order to produce the desired layer thickness upon complete deposition. The metal to be deposited or the metals to be deposited are in the electroplating bath in the form of Complexes. Furthermore, common additives such as auxiliary agents for deposition, brighteners and the like. included in the electroplating bath.

If, for example, a galvanic coating is to be produced from fine gold, an aqueous gold sulfite bath can be used that is largely non-toxic and has a basic pH value.

Similarly, other suitable electroplating baths can be used to produce metal coatings from other noble metal alloys or from non-noble metal alloys.

It is also possible to deposit different noble metal coatings and non-noble metal coatings one after the other. Which metals are deposited on the duplicate model 30 depends on the intended use and the requirements placed on it. After the galvanic deposition, the duplicate stump 30 is dissolved and the conductive coating 36 is removed. In the case shown, a metal coating remains in the form of a cap, which consists of one or more metal layers.

A thin ceramic layer can also be applied as the top layer, for example by CVD, e.g. a titanium nitride layer. Even in this way, favorable aesthetics can be achieved without the need for a layer of noble metal, provided that the rope is particularly inexpensive to work with.

The type of metals used and the layer thickness is chosen so that the molding as a support structure for the application a facing 18 made of ceramic or plastic can serve.

In the case of veneering using ceramics, this takes place in a known manner using suitable ceramic materials, for example using lithium silicate glass ceramics, which are fired at temperatures in the range between approximately 700 and 850 ° C. Electrical deposition ("Electro Deposited Ceramics") is also possible.

In the embodiment according to FIG. 1 a, the galvanically deposited layer 12 is chemically dissolved again after the production of the ceramic veneer 18, so that an all-ceramic prosthetic molded part 10 a remains at the end of the process.

In such a case, the metal layer 12 merely serves as a fireproof support structure for the application of the ceramic veneer 18. The metal layer 12 enables an increase in the preparation accuracy and possibly a reduction in the layer thickness of the molded part 10a, in particular in the side area.

In FIG. 1 a, the dashed line 14 indicates the original inner contour of the metal layer 12, which is removed after the ceramic veneer 18 has been completed, the all-ceramic molded part 10 a with the inner contour 16 then remaining.

The metal layer 12, which is chemically dissolved after the completion of the ceramic veneer 18, can, as above already mentioned, consist of a noble metal alloy or a non-noble metal alloy. For ease of handling and inexpensive production, however, it is preferred if a non-noble metal alloy is used to produce the metal layer 12. All possible non-precious alloys, but also iron alloys come into question. The use of a cobalt or nickel alloy has proven to be particularly advantageous, since this ensures good mechanical stability during the firing process of the ceramic, even small layer thicknesses of the metal layer 12 of the order of approximately 50 μm being sufficient.

In principle, layer 12 can also be made of a particularly oxidation-resistant metal, e.g. a CrMoCo alloy is produced, which ensures the load-bearing capacity of the molded part and, for reasons of simplification, after coating with a thin gold layer of e.g. 10 μm and application of a ceramic veneer is not removed.

A variant of this embodiment is shown in FIG. 1b and is designated overall by the number 10b. Here, a first metal layer 12 is first electroplated onto the duplicate stump 30, onto which a second metal layer 20 with a generally lower layer thickness is then electroplated.

The metal molding thus produced is then again preferably provided with a ceramic veneer 18, or alternatively with a plastic veneer. In this case, the first metal layer 12 serves to ensure the mechanical stability during the production of the ceramic veneer 18. For example, a nickel alloy or a cobalt alloy (or pure nickel or cobalt) can be used for this purpose. The layer thickness for the first metal layer 12 is usually in a range from approximately 10 to 200 μm, preferably in the range between approximately 30 and 80 μm. In contrast, a noble metal alloy is preferably used for the second metal layer 20, for example a gold-based alloy, which is only applied with a considerably thinner layer thickness, for example approximately 5 to 10 μm.

After the later chemical dissolution of the first metal layer 12, the ceramic molded part 10b then remains, which is provided on its inner surface with the noble metal coating 20, as a result of which very appealing aesthetics can be achieved with only very little noble metal consumption, with at the same time optimal biocompatibility of the molded part 10b and utilization improved stability and good cementability. With this design, an approximation to the translucency of the natural tooth is largely guaranteed. The reflection properties can be adapted in a targeted manner depending on the thickness and nature of the precious metal layer 20. In this way, an improved UV curing can be achieved with veneers made of ceramic or plastic.

Compared to conventional molded parts, the consumption of precious metals is significantly reduced by the significantly reduced layer thickness of the precious metal layer 20. Conventionally, a bonder is also applied to the underlying metal layer 12 or 20 before applying a ceramic veneer. This can be a thin, for example gold-containing layer.

After the application of the ceramic veneer 18, which results in the desired shape in a first firing process, one or more ceramic cover layers are usually applied in order to achieve the desired stability, surface quality and color.

In the method according to the invention, however, it is generally possible to dispense with the application of a bonding layer, a thin noble metal layer preferably being used as the uppermost layer before the ceramic layers are applied, in which ceramic dispergate may also be embedded, as will be explained in more detail below. As already mentioned, a ceramic cover layer is also conceivable in order to apply the veneer thereon.

A further variant of a molded part according to the invention is shown in FIG. 1c and is designated overall by the number 10c.

In this case, a metallic multilayer structure comprising a first layer 12, a second layer 22 and a third layer 20 is electrodeposited on the duplicate model 30.

The first layer 12 could, for example, again be a nickel layer which provides the necessary strength when firing ceramic. The metal frame is sufficiently form stable and has little internal stress that could cause deformation.

On this first layer, which can have a thickness of about 50 μm, for example, a second layer 22 is e.g. made of a corrosion-resistant CrCo alloy with a layer thickness of e.g. 50 μm deposited. A third layer 20 of fine gold with a thickness of 5 μm is deposited thereon.

Again, after removing the model 30 and the

Lead 34 the production of the ceramic veneer 18 in one or more firing processes. The first layer 12 is then chemically dissolved.

This creates a high-quality prosthetic molded part 10c with good long-term mechanical stability and good biocompatibility at the same time. The additional, thin noble metal layer 20 simultaneously ensures improved adhesion of the ceramic layer 18 and enables the aesthetics to be adjusted to approximate the translucency of the natural tooth.

Since only a very thin layer of precious metal is necessary, the costs are reduced considerably compared to conventional manufacturing processes.

It goes without saying that the examples given above with ceramic veneer can also be carried out with plastic veneer. Some examples of possible alloy compositions are given below:

1. 20-100% by weight of cobalt with additions of nickel and / or iron

2. 95-100% by weight of nickel with additions of cobalt and / or iron

3. 10-30% by weight chromium with 70-90% by weight cobalt and / or iron

4. 90-100% by weight of silver with additions of cobalt and / or tin

5. 98-100% by weight of gold with additions of platinum, silver, copper and / or cobalt

6. 20-30% by weight of molybdenum and / or tungsten with 70-80% by weight of cobalt and / or iron and up to 5% by weight of chromium

Some suitable electroplating bath compositions for the deposition of certain alloys are given below:

I. Electroplating bath for the deposition of nickel, cobalt and binary and ternary alloys of these metals with iron.

Composition:

Nickel sulfate, 6 * water 150 g / 1

Nickel chloride, 6-water 90 g / 1

Iron sulfate, 7 * water 40 g / 1 Boric acid 49 g / 1

Sulfolen 0.4 g / 1

Iso-ascorbic acid 2.0 g / 1 o-sulfobenzimide (sodium salt) 3.6 g / 1

Sodium allyl sulfonate 3.5 g / 1

1, 4-Di- (Hydroxyethoxy) -2-butyne 0.1 g / 1 pH 3.2

Bath temperature 55 ° C

Cell current 2 A

Exposure time 10 min

Current density up to 12 A / dm ²

It can be used to deposit evenly shiny and leveled nickel-iron layers.

II. Additional mixture for galvanic chrome (III) baths

Composition:

Chromium (III) ions 26 g / 1

Sodium fluoroborate 110 g / 1

Vanadium ions 0.55 g / 1

Ammonium chloride 90 g / 1

Boric acid 50 g / 1

Ammonium formate 50 g / 1

Mixture of the dihexyl ester of Na sulfosuccinic acid and the Na sulfonate of 2-thyl-l-hexanol 0.1 g / 1 pH 3.5 - 4.0

Bath temperature 27-32 ° C

Current density 10.8 A / dm ²

It can be used to produce shiny, well covering chrome coatings even at low current densities.

III. Galvanic deposition of ternary Cr-Fe-Ni alloys

Composition:

Ammonium or potassium chrome alum NH ₄ - or

KCr (S0 ₄ ) ₂ -12H ₂ 0 400 g / 1

Nickel sulfate NiS0 ₄ -7 H ₂ 0 55 g / 1

Ammonium iron (II) sulfate (NH ₄ ) ₂ Fe (S0 ₄ ) ₂ ^« 6H ₂ 0 40 g / 1

Sodium citrate 2 hydrate Na ₃ C ₆ H ₅ 0 ₇ • 2H ₂ 0 70 g / 1

Sodium fluoride NaF 8 g / 1

Bath temperature 40-60 ° C

Cell current 1-4 A / dm ² IV. Electroplating of cobalt-tungsten alloys

Composition:

Cobalt sulfate CoS0 ₄ -7H ₂ 0 2-19 g / 1

Sodium tungstate Na ₂ Wo ₄ -2H ₂ 0 22-85 g / 1

Ammonia solution 25% NH ₄ OH 40-45 g / 1

Ammonium sulfate (NH ₄ ) ₂ S0 ₄ 132-300 g / 1

Sodium hydroxide NaOH 0-10 g / 1

Bath temperature 30-40 ° C

Current density 1-4 A / dm ²

If it is not intended to produce all-ceramic products during the production of the prosthetic molded part, but rather metal-ceramic composite products, good adhesion between the uppermost metal layer and the applied ceramic layer is necessary. For this purpose, for example, the uppermost metal layer can be mechanically pretreated by sandblasting before coating with ceramic, in order to produce an increase in the effective bond area, better wettability and better adhesion.

In the case of non-noble metal alloys, the mechanical adhesion can additionally be improved by oxidation, dentrite formation, by electrochemical corrosion of the metal surface by molten glass when the ceramic is fired, by selective oxidation at the grain boundaries and by pretreatment of the surface using etching solutions. These possibilities exist with oxidizable alloys, which include Cu, Co, Cr, Ni, Ag or their alloys. The adhesion of the ceramic is finally improved by the shrinking of the ceramic mass during the cooling process and the associated compression forces.

A favorable setting of the expansion behavior of metal and ceramic is of great importance for the strength of the composite.

The basic principle here is that the thermal expansion of the metal should be greater than that of the ceramic. Due to the higher compressive strength than the tensile strength of the ceramic and the compressive stress caused by the thermal expansion difference during the cooling process, this difference leads to a stabilization of the bond.

A further improvement in adhesion can be achieved by adding ceramic dispersants in the top metal layer. Here, for example, Al ₂ O ₃ , Si ₃ N ₄ , SiC with a particle size in the range from about 0.01 to 5 μm come into consideration, which are deposited, for example, with 20 to 30% by volume in the uppermost metal layer. The deposition is carried out as usual. Only the last galvanization phase has changed. A particle suspension is added in the bath by a metering pump, which is directly galvanized into the surface by the deposited electroplating layer. The particle mixture is metered in finely distributed in the last 20 minutes of the separation process. If the metal layer with ceramic deposits produced in this way is subjected to a subsequent fire in the ceramic furnace, the surface layer is restructured. The particle-rich layer with a globular structure forms a tube-like structure with cavities. implemented layer, which is an integral part of the metal layer. The ceramic engages in this layer during the subsequent firing of a ceramic veneer and is securely anchored.

Coating the metal framework with ceramics does not require any special ceramic materials or special coating techniques. A special temperature control is also not necessary.

All conventional ceramic systems can be used on the prosthetic molded parts according to the invention.

For example, the ceramic IPS Classic V from Ivoclar AG, Liechtenstein, can be used, e.g. is fired in an oven-Programat P90 (Ivoclar). The firing temperatures depend on the manufacturer's instructions.

Known chemicals are available for the chemical dissolution of individual metal layers, for example after the ceramic veneer has been applied.

Silver, cobalt, iron / cobalt and the like can be dissolved using nitric acid.

The use of 70-90% sulfuric acid at 40-80 ° C is suitable for iron and chrome alloys.

Only for metal alloys that are difficult to oxidize, such as gold alloys, CrCo alloys, CrMoCo alloys and the like, is it necessary to use aqua regia, ie a mixture of one part of nitric acid with three parts of hydrochloric acid.

Claims

claims Method for producing prosthetic molded parts (10a, b, c) for the dental field, in which a model (30) of a molded part (10a, b, c) is produced by an impression technique, the model (30) in at least one coating step is coated with a metal layer (10, 20, 22) in order to produce a molded article after removal of the model (30), which is provided with a ceramic or plastic facing (18), characterized in that at least one metal layer (12) after the manufacture of the veneer (18) is removed again. Method for producing prosthetic molded parts (10a, b, c) for the dental field, in which a model (30) of a molded part (10a, b, c) is produced by an impression technique, the model (30) in at least one coating step is coated with a metal layer (10, 20, 22) in order to produce a molded article after removal of the model (30), which is provided with a facing (18) made of ceramic or plastic, characterized in that at least one further layer (12 ) is deposited on the metal layer by an electrochemical deposition process or a physical deposition process under vacuum or protective gas. Method according to Claim 1 or 2, characterized in that the model (30) is first of all equipped with an electrically conductive Coated coating (36) and is contacted with an electrical lead (34), and that at least one metal layer (12, 20, 22) is electrodeposited. 4. The method according to any one of the preceding claims, characterized in that the further layer is deposited galvanically, by CVD or PVD. 5. The method according to any one of claims 1 to 4, characterized in that a noble metal-containing layer (noble metal layer), preferably a gold-containing layer, or a ceramic layer, preferably a titanium nitride layer, is deposited on which the veneer (18) is applied. 6. The method according to any one of the preceding claims, characterized in that the molding is produced as a stable support body for the manufacture of the veneer (18). 7. The method according to claim 6, characterized in that the veneer is made of ceramic, and that the molding is designed as a fire-stable support body for the production of the veneer. 8. The method according to claim 5, 6 or 7, characterized in that the layer to which the veneer (18) is applied is applied with a layer thickness which is not sufficient as a base layer for firing a ceramic, in particular with a layer thickness in Range of about 1 to 50 microns, preferably from about 5 to 15 microns is applied. 9. The method according to any one of claims 4 to 8, characterized in that ceramic Dispergate are embedded in the electrodeposited layer. 10. The method according to any one of the preceding claims, characterized in that _(. 12, 22) at least one metal layer of a base metal (base metal layer) is applied. 11. The method according to any one of claims 5 to 10, characterized in that the noble metal layer (20) after the production of the veneer (18) is removed. 12. The method according to any one of the preceding claims, characterized in that at least two non-precious metal layers (12, 22) are produced one above the other. 13. The method according to claim 10, 11 or 12, characterized in that at least one non-precious metal layer (12, 22) is formed as a carrier layer for firing the ceramic. 14. The method according to any one of claims 10 to 13, characterized in that at least one base metal layer (12, 22) is applied with a total layer thickness of about 5 to 300 microns. 15. The method according to any one of claims 10 to 14, characterized in that at least one non-precious metal layer (12, 22) made of a nickel, cobalt or iron alloy, in particular with alloy proportions of chromium, molybdenum or tungsten is applied. 16. The method according to any one of claims 10 to 15, characterized in that at least one non-noble metal layer is applied, which has up to 10 wt .-% of further fractions, such as copper, antimony, selenium or ceramic disgate. 17. The method according to any one of claims 10 to 16, characterized in that a non-noble metal layer (12) made of a cobalt alloy, a nickel alloy or a silver alloy is applied. 18. The method according to any one of claims 10 to 17, characterized in that at least one base metal layer (12) is removed after the manufacture of the veneer (18). 19. The method according to any one of claims 10 to 18, characterized in that a first base metal layer (12) is produced from a nickel alloy, on which a second base metal layer (22), in particular from a chromium / cobalt alloy, is produced, and that after Production of the veneer, the first base metal layer (12) is removed. 0. Prosthetic molded part for the dental field, produced according to one of the preceding claims.