Method for producing dental polychrome glass ceramic blanks, polychrome glass ceramic blanks, and uses thereof

Abstract

To provide a method for producing a multicolor glass-ceramic blank.SOLUTION: The present invention relates to a method of producing a multicolor glass-ceramic blank (10) for dental purposes. The glass-ceramic blank (10) is produced from at least a first material powder (18) and a second material powder (20), wherein the first material powder (18) and the second material powder (20) are different-colored and wherein at least one of the first material powder (18) and the second material powder (20) has nanoparticles (14) and / or glass-ceramic particles (16). In the process of this method, the first material powder (18) and the second material powder (20) are introduced into a mold (22) to form powder mixture aggregate (26). The powder mixture aggregate (26) is compressed by hot pressing to form the glass-ceramic blank. The present invention further relates to a multicolor glass-ceramic blank (10), and the use of the multicolor glass-ceramic blank (10) as dental material.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a polychrome dental glass-ceramic blank. [Background technology]

[0002] The invention also relates to a multicolored glass-ceramic blank obtainable by such a method.

[0003] The invention further relates to the use of such a polychrome glass-ceramic blank as a dental material.

[0004] In this context, the use of glass ceramic blanks in dental technology is known. Polychromatic glass ceramic blanks have the advantage that they can reproduce the optical properties of natural tooth materials very well, especially compared to monochromatic glass ceramic blanks. That is, polychromatic glass ceramic blanks are particularly suitable for producing aesthetically demanding dental restorations with very good optical and mechanical properties. In this case, optical properties refer not only to color but also to the translucency of dental restorations. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to further improve known methods for producing polychrome glass-ceramic blanks, and more particularly to provide a method with which polychrome glass-ceramic blanks can be easily produced, which reproduce natural tooth material very well, which can be easily machined to the shape of the final desired dental restoration, and which can be converted after molding into a dental restoration with excellent mechanical and optical properties. [Means for solving the problem]

[0006] This problem is solved by a method for manufacturing a multicolor dental glass-ceramic blank. The glass-ceramic blank is manufactured from at least a first material powder and a second material powder, the first material powder and the second material powder having different colors. At least one of the first material powder and the second material powder contains nanoparticles and / or glass-ceramic particles. The method includes introducing the first material powder and the second material powder into a mold to form at least one powder mixture agglomerate, and compressing the powder mixture agglomerate by hot pressing to form the glass-ceramic blank.

[0007] The method of the present invention includes several variations.

[0008] In a first variant of the method of the present invention, the first and second material powders are each introduced into a mold in a dry state. Optionally, the first and / or second material powders form a pelletized substance. In this case, the first and second material powders are metered into the mold to produce a defined continuous progression of optical properties, in particular a continuous color progression. In this variant, it is also possible to directly process the powder mixture agglomerate formed by the first and second material powders by hot pressing to obtain a glass ceramic blank. Optionally, the powder mixture agglomerate is processed via an intermediate heat treatment step to obtain a glass ceramic blank. In the intermediate heat treatment step, at least one component of the powder mixture agglomerate that is not necessary for the glass ceramic blank can be thermally removed. For example, in this connection, the binder can be burned out by the heat treatment.

[0009] In a second variant of the method of the invention, the powder of the first material and / or the powder of the second material are introduced into the mold as a suspension. The suspension is in particular an aqueous suspension of the powder of the first material and / or an aqueous suspension of the powder of the second material. In this variant, the powder mixture agglomerate must always be dried before it is further processed to obtain the glass ceramic blank. That is, a drying step is carried out in this case. The dried powder mixture agglomerate is then directly further processed to obtain the glass ceramic blank. As described above in relation to the first variant, in the second variant as well, it is possible to provide an intermediate step for producing a green body (unsintered compact) and / or an intermediate step for producing a body-in-white.

[0010] In a third variant, the powders of the first and second materials are introduced into the mold in the form of a green body containing the powders of the first and second materials, the green body being obtained from a preliminary process, in which case the powder mixture agglomerate is formed by the green body.

[0011] In a fourth variant, the first and second material powders are introduced into the mold in the form of a body-in-white containing the first and second material powders, the body-in-white being obtained from a preliminary process. In this variant, the powder mixture agglomerate is formed by the body-in-white.

[0012] In all variations, the first material powder and / or the second material powder contain nanoparticles and / or glass ceramic particles. This encompasses nine variations. In variation A, the first material powder contains nanoparticles. In variation B, the second material powder contains nanoparticles. In variation C, both the first material powder and the second material powder contain nanoparticles. In variation D, the first material powder contains glass ceramic particles. In variation E, the second material powder contains glass ceramic particles. In variation F, both the first material powder and the second material powder contain glass ceramic particles. In variation G, the first material powder contains both nanoparticles and glass ceramic particles. In variation H, the second material powder contains both nanoparticles and glass ceramic particles. In variation I, both the first material powder and the second material powder contain nanoparticles and glass ceramic particles.

[0013] In contrast to the prior art, in none of the above-described variants A to I do both the first and second material powders consist of glass powder. In this case, it is of course not excluded that the first and / or second material powders also contain glass powder. The use of glass ceramic particles and / or nanoparticles has the advantage of simplifying the production of the glass ceramic blank. Since the glass ceramic particles already contain nucleation and / or crystallization sites, they are stable under pressure up to a certain temperature. This eliminates the possibility of premature compaction. This prevents undesired gas incorporation. Regarding nanoparticles, they offer a relatively large surface area for a given volume, which is advantageous for surface crystallization. Therefore, a crystalline structure can be formed in a relatively short time. Thus, the glass ceramic particles and / or nanoparticles are selected to facilitate or actually enable the production process, since they serve as nuclei for the crystallization of other phases at a later stage. Alternatively or additionally, the glass ceramic particles and / or nanoparticles may be selected to have a desired effect on the optical and / or mechanical properties of the glass ceramic blank. In particular, glass ceramic particles and / or nanoparticles can be used to impart a desired color progression and / or a desired translucency progression to the glass ceramic blank. Furthermore, glass ceramic particles and / or nanoparticles can be used to create a desired opalescence progression and / or a desired fluorescence progression. For this purpose, the glass ceramic particles and / or nanoparticles must have suitable opalescence and / or fluorescence properties. In this way, the optical properties of natural teeth can be reproduced particularly well.

[0014] Nanoparticles in this specification are understood to mean particles with a size between 1 nm and 100 nm.

[0015] In the context of the present invention, glass-ceramic particles are understood to mean to include both nucleated glass-ceramic particles and crystallized glass-ceramic particles.

[0016] The glass-ceramic particles have a particle size of more than 100 nm and less than 2 mm.

[0017] In one embodiment, the first and second material powders are introduced into the mold in locally different mixing ratios, thereby creating a color progression in the glass ceramic blank. In this way, it is possible to easily and reliably create a continuous color progression in the glass ceramic blank. The color progression may also vary locally within the glass ceramic blank. Because the powders are introduced into the mold, the color progression can be very precisely adjusted.

[0018] In one variant, the powder mixture agglomerate is heat-treated. This can be useful, in particular, for thermally removing components in the powder mixture agglomerate that are undesirable for the glass-ceramic blank. This is also called baking. For example, such a heat treatment can remove binders from the powder mixture agglomerate. Furthermore, the heat treatment can cause pre-sintering.

[0019] In one variant, at least one of the first and second material powders comprises rounded glass particles, rounded nanoparticles, and / or rounded glass ceramic particles. In this regard, the rounding improves the free flow of the glass particles, nanoparticles, and / or glass ceramic particles. This is particularly true compared to non-rounded particles. The rounding facilitates the introduction of the first and second material powders into a mold. This is particularly useful when the first and second material powders are introduced directly into a mold. Therefore, it is possible to omit preliminary processes for producing a green body and / or a body-in-white. This simplifies the method for producing a glass ceramic blank.

[0020] The glass particles, nanoparticles and / or glass ceramic particles can be rounded, for example, mechanically. In this connection, the glass particles, nanoparticles and / or glass ceramic particles are crushed using crushing bodies. Alternatively or additionally, the glass particles, nanoparticles and / or glass ceramic particles can be thermally crushed. For this purpose, the glass particles, nanoparticles and / or glass ceramic particles can be subjected to a plasma treatment.

[0021] In the context of the present invention, the glass particles used may be a material system for forming glass ceramics by fusion casting, which is suitable for forming lithium disilicate and / or lithium metasilicate.

[0022] The glass-ceramic particles can be any composition already crystallized from the group of glass particles mentioned above at different crystallization stages. These can optionally contain pigments, such as fluorescent pigments, such as europium-doped strontium aluminate. Europium-doped strontium aluminate is described in EP 3 696 150 A1, which is incorporated herein by reference.

[0023] In the context of the present invention, the nanoparticles may also be pigments or opacifiers.

[0024] Additionally, nanoparticles can contain ceramic components as defects in the microstructure to tailor processing properties, such as various modifications of zirconium dioxide, aluminum oxide, and silicon dioxide.

[0025] Additionally, the nanoparticles can take the form of nucleating agents (eg, metal colloids, other external crystals) for heterogeneous nucleation.

[0026] Furthermore, in relation to the nanoparticles, it is also possible to use particularly small particles from the group of glass particles or glass-ceramic particles, which helps to increase the sinterability.

[0027] In the compaction of the powder mixture agglomerate by hot pressing, the powder mixture agglomerate can be placed in a mold, i.e., hot pressing is carried out in a mold into which the first and second material powders are introduced to form the powder mixture agglomerate. Therefore, the method of the present invention is carried out using only a single mold into which the first and second material powders are introduced and hot pressing is applied. This allows the method to proceed particularly efficiently.

[0028] When compressing the powder mixture agglomerate by hot pressing, the powder mixture agglomerate can first be heated to a temperature of at least 700°C, and then a compressive force can be applied. Heating the powder mixture agglomerate to 700°C ensures that the powder mixture agglomerate is degassed. Only after that can the compressive force be applied. In this way, a high-quality glass ceramic blank can be produced. This is particularly true when the first and second material powders are introduced directly into a mold, eliminating the intermediate steps for forming a green body and / or a white body.

[0029] The attainment of a temperature of at least 700°C can be used as a trigger criterion for applying a compressive force. The powder mixture agglomerate is therefore monitored for its temperature. This is based on the knowledge that the powder mixture agglomerate is sufficiently degassed once a temperature of 700°C is reached. In this way, the entire process, and in particular the hot-press compression, can be easily and reliably controlled.

[0030] The powder mixture agglomerate is preferably compressed by hot pressing to a density of at least 99.9% of the density of the base material of the first material powder and / or the base material of the second material powder. In other words, the glass ceramic blank after hot pressing has a density that essentially corresponds to the density of the base material of the first material powder and / or the base material of the second material powder. In this way, a glass ceramic blank with high mechanical quality can be produced.

[0031] In one embodiment, the first material powder and the second material powder are introduced into a mold at at least two separate locations to form at least two powder mixture agglomerates. Using such a mold, it is possible to produce at least two glass ceramic blanks, one from each powder mixture agglomerate. Because such a mold can be used to simultaneously produce two or more glass ceramic blanks, such a mold is also referred to as a multiple mold. In this manner, a relatively large number of glass ceramic blanks can be produced in a relatively short period of time.

[0032] Generally speaking, the method of the invention can therefore be carried out in this manner in connection with a single mould, i.e. a mould designed to produce a single glass-ceramic blank, or in connection with a plurality of moulds.

[0033] The hot-pressing of the powder mixture aggregate can be carried out at temperatures between 650°C and 980°C, particularly between 700°C and 750°C, and at pressures between 5 MPa and 50 MPa, preferably between 10 MPa and 30 MPa. This results in a glass-ceramic blank of high mechanical and optical quality. At the same time, temperatures that are too low from a material-specific point of view, and therefore do not allow compaction or lead to undesirable gas inclusions, are avoided. Similarly, excessively high material-specific temperatures that could lead to the formation of undesirable crystals are avoided.

[0034] The powder mixture aggregate can be compressed by hot pressing for 0.1 to 10 minutes, preferably 0.3 to 5 minutes. That is, the molding by hot pressing takes a relatively short time. Therefore, it is possible to produce a glass ceramic blank in a relatively short time. In this case, it goes without saying that the mechanical and optical requirements for the glass ceramic blank are simultaneously satisfied.

[0035] The hot-pressing of the powder mixture agglomerates can be carried out at atmospheric pressures below 0.1 bar, preferably between 0.01 and 0.08 bar. Briefly, the hot-pressing of the powder mixture agglomerates is carried out under reduced pressure, which reduces or eliminates undesired reactions with the surrounding atmosphere. This also protects the mold.

[0036] In one variant, the glass ceramic blank is a multi-piece blank. This means that the glass ceramic blank is designed for use in two or more dental restorations. This means that the glass ceramic blank must be divided into at least two pieces before, during, or after the fabrication of the dental restorations. The glass ceramic blank can be, for example, cut or split. This is preferably done before the fabrication of the dental restorations. The blanks may be separated in a milling or grinding machine during or after the fabrication of the dental restorations. In this case, the separation involves removing material. By producing multiple blanks in this way, it is possible to efficiently and reliably produce many glass ceramic blanks in a short period of time.

[0037] The method also includes opening the mold and removing the glass ceramic blank. In this case, the mold is opened while both the mold and the glass ceramic blank are still hot. In this connection, the method is also referred to as hot demolding or hot demolding. In other words, the mold and the glass ceramic blank therein are not cooled in a defined manner before the mold is opened and the glass ceramic blank is removed. This increases the utilization efficiency of the mold. Of course, the glass ceramic blank is then cooled outside the mold.

[0038] The object of the present invention is also achieved by a polychromatic glass ceramic blank obtained by the method of the present invention. As already explained, such a glass ceramic blank can be produced efficiently, which includes, in particular, cost-effectively. The glass ceramic blank has high quality from mechanical and optical aspects. Therefore, the glass ceramic blank can be further processed to obtain a dental restoration. In particular, such a blank can be used to produce crowns, abutments, abutment crowns, inlays, onlays, veneers, bridges, and overdentures. Due to the mechanical and optical properties of the glass ceramic blank, the dental restoration also has good mechanical and optical properties.

[0039] In addition, the object of the present invention is also achieved by using the polychrome glass ceramic blank of the present invention as a dental material. In particular, the polychrome glass ceramic blank of the present invention is used to produce dental restorations. Due to the good mechanical and optical properties of the glass ceramic blank, it is possible to produce dental restorations with good mechanical and optical properties.

[0040] The invention will now be described with reference to various embodiments shown in the accompanying drawings. [Brief explanation of the drawings]

[0041] [Figure 1] 1 is an illustration of a polychrome glass-ceramic blank of the invention produced by the method of the invention and its use for making a dental restoration. FIG. [Figure 2] 2 is an explanatory diagram showing the sequence of the method of the present invention for producing the polychrome glass ceramic blank in FIG. 1. FIG. [Figure 3] FIG. 3 is an explanatory diagram showing a modified example of the method in FIG. 2. [Figure 4] FIG. 3 is an explanatory diagram showing a further modification of the method in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0042] FIG. 1 shows a multicolored glass-ceramic blank 10 .

[0043] The glass-ceramic blank 10 comprises a glass-ceramic primary phase 12 with both nanoparticles 14 and glass-ceramic particles 16 embedded in the primary phase 12 .

[0044] In FIG. 1, the nanoparticles 14 and glass-ceramic particles 16 are shown merely symbolically and to an excessive extent.

[0045] Glass-ceramic particles 16 differ from the main phase 12 of the glass-ceramic in that they were already present during the production of the main phase 12, as will be explained in more detail below.

[0046] The glass ceramic blank 10, and in particular the main phase 12, is produced from material powders of different colors, so that the color of the glass ceramic blank 10 progresses continuously, as indicated in FIG. 1 by hatching of different widths.

[0047] The glass ceramic blank 10 is used as a dental material for producing a dental restoration R.

[0048] In this connection, the glass ceramic blank 10 is machined in step (a) by removing material to take the shape of the dental restoration R to be produced. It goes without saying that the dental restoration in Figure 1 is shown only diagrammatically.

[0049] In step (b) following step (a), the glass-ceramic blank 10 that has been processed by removing material is thermally hardened, which involves a crystallization process within the glass-ceramic blank 10, which establishes the mechanical properties of the glass-ceramic blank 10.

[0050] The dental restoration R thus produced can then be used on the patient.

[0051] The glass ceramic blank 10 is produced by the method described below with reference to FIGS.

[0052] In the example according to FIG. 2, in a first method step A, a powder of a first material 18 and a powder of a second material 20 are introduced into a mold 22 .

[0053] The first powder material 18 and the second powder material 20 have different colors.

[0054] The first material powder 18 also contains nanoparticles 14 and glass particles 24 .

[0055] The powder of the second material 20 includes glass-ceramic particles 16 and glass particles 24 .

[0056] In this case, the glass particles 24, the nanoparticles 14 as well as the glass-ceramic particles 16 are rounded.

[0057] Furthermore, the first material powder 18 and the second material powder 20 are introduced into the mold 22 in locally different mixing ratios.

[0058] It goes without saying that the glass particles 24, nanoparticles 144, and glass ceramic 16 in Figure 2 are shown schematically and greatly enlarged. To represent the different coloring, the glass particles 24 of the first material powder 18 are shown as squares, and the glass particles 24 of the second material powder 20 are shown as circles. For clarity, only some of the particles are labeled with reference numerals.

[0059] In the illustrated embodiment, the lower region of the mold 22 has a greater proportion of powder of the first material 18 than powder of the second material 20. The opposite is true in the upper region of the mold 22.

[0060] Because the first material powder 18 and the second material powder 20 are different in color, this results in a color progression within the powder mixture agglomerate 26 formed by introducing the first material powder 18 and the second material powder 20 into the mold 22. This color progression is maintained in the finished glass-ceramic blank 10.

[0061] The powder mixture agglomerate 26 may optionally be compressed into a green body in a mold 22 .

[0062] Additionally, optionally, the powder mixture agglomerate 26 can be heat treated.

[0063] In the subsequent method step B, the powder mixture agglomerate 26 is compressed by hot pressing, in this way forming the glass ceramic blank 10 from the powder mixture agglomerate 26.

[0064] For this purpose, the powder mixture agglomerate 26 is left in the mold 22 .

[0065] In detail, in the process of hot pressing, the powder mixed agglomerate 26 is first heated to a temperature of 700° C. Only when the powder mixed agglomerate 26 reaches a temperature of 700° C., a compressive force F is applied to the powder mixed agglomerate 26. In other words, reaching a temperature of 700° C. is the trigger criterion for applying the compressive force F.

[0066] The compressive force F is selected so that the powder mixture agglomerate 26 is subjected to a pressure of between 10 MPa and 30 MPa. In the example shown, the pressure is 20 MPa.

[0067] Furthermore, the temperature of the powder mixture agglomerate 26 is increased during the application of the compressive force F. In the illustrated embodiment, the temperature is increased to 730°C.

[0068] Additionally, the compression is performed in a vacuum chamber V. The pressure in the vacuum chamber V is between 0.01 bar and 0.08 bar.

[0069] In the illustrated embodiment, the above pressure and temperature are maintained for 4 minutes.

[0070] Thereafter, in method step C, the mold 22 is opened and the glass-ceramic blank 10 is removed from the mold 22. This essentially takes place immediately after method step B. There is therefore no defined cooling operation.

[0071] It will be appreciated that the opening of the mould 22 in method step C is merely schematic and the mould 22 can be opened in any other suitable manner.

[0072] The glass ceramic blank 10 produced in this manner achieves a density of 99.9% of that of the base material in the first material powder 18 .

[0073] With regard to the geometric dimensions of the glass ceramic blank 10, the blank dimensions are such that a single dental restoration R can be produced from the glass ceramic blank 10 by the method described above with reference to FIG.

[0074] The glass ceramic blank 10 can be configured as a crown blank, an inlay blank, or a bridge blank. Such blanks and corresponding dimensions are known.

[0075] For example, the crown blank may have dimensions of 18.4 mm x 14.7 mm x 12.5 mm. The bridge blank may have dimensions of 15 mm x 32 mm x 15 mm.

[0076] FIG. 3 shows a variation of the method in FIG.

[0077] In this case, only the differences with respect to the method of Figure 2 will be described, and elements that are the same or correspond to each other are given the same reference numerals.

[0078] The interior of the mould 22 used in the variant according to FIG. 3 is essentially twice as large as the mould 22 used in the method according to FIG.

[0079] 3, it is therefore possible to produce glass ceramic blanks 10 that are at least twice as large as those that can be produced by the method of FIG.

[0080] The dimensions of the glass ceramic blank 10 produced by the method according to FIG. 3 are therefore such that two dental restorations R can be produced from the glass ceramic blank 10 by the method described with reference to FIG.

[0081] It goes without saying that a glass ceramic blank 10 for producing more than two dental restorations R is also conceivable.

[0082] The glass-ceramic blank 10 that can be produced according to the variant shown in FIG. 3 can therefore also be called a multi-layer blank 28 .

[0083] A separation plane 30 can be provided in the multi-layer blank 28. When the multi-layer blank 28 is separated along this separation plane 30, two glass-ceramic blanks 10 are obtained, the dimensions of which correspond to the glass-ceramic blanks 10 obtained by the method according to FIG.

[0084] FIG. 4 shows a further variant of the method for producing a glass-ceramic blank 10 .

[0085] Again, only the differences with respect to the method according to Figure 2 will be described, and elements that are the same or correspond to each other are provided with the same reference signs.

[0086] Again, the difference concerns the type 22 used.

[0087] 4, the mold 22 has two cavities 32, 34, each capable of receiving a powder mixture agglomerate 26 for producing the glass-ceramic blank 10. In other words, such a mold 22 makes it possible to simultaneously produce two glass-ceramic blanks 10, the dimensions of which correspond to the glass-ceramic blanks 10 obtainable by the method according to FIG.

[0088] 4, in method step A, the powder of the first material 18 and the powder of the second material 20 are thus introduced into at least two separate locations (corresponding to the cavities 32, 34) in the mold 22. In this way, two separate powder mixture agglomerates 26 are formed.

[0089] Such a mold 22 may also be referred to as a multiple mold 36 .

[0090] The above-mentioned examples may also be combined. In this connection, one possible variant is to carry out the method using a multiple mold designed to produce two or more multiple blanks, which makes it possible in particular to produce a large number of glass-ceramic blanks simultaneously. [Prior art documents] [Patent documents]

[0091] [Patent Document 1] European Patent Application Publication No. 3696150 [Explanation of symbols]

[0092] 10 Glass ceramic blanks 12 Main phase 14 Nanoparticles 16 Glass ceramic particles 18 First material powder 20 2nd material powder 22-inch 24 Glass particles 26 Powder mixed aggregate 28 Multiple Blanks 30 separation plane 32 Cavity 34 Cavity 36 Multiplex type F Compression force R Dental restoration V Vacuum Chamber

Claims

1. 1. A method for manufacturing a multicolored dental glass-ceramic blank (10) composed of at least a first material powder (18) and a second material powder (20), wherein the first material powder (18) and the second material powder (20) have different colors, and at least one of the first material powder (18) and the second material powder (20) comprises nanoparticles (14) and / or glass-ceramic particles (16), the method comprising: - introducing the powder of the first material (18) and the powder of the second material (20) into a mold (22) to form at least one powder mixture agglomerate (26); - forming the glass-ceramic blank (10) by compressing the powder mixture agglomerate (26) by hot pressing; A method comprising:

2. 2. The method of claim 1, wherein the first material powder (18) and the second material powder (20) are introduced into the mold (22) in locally different mixing ratios, thereby producing a color progression in the glass-ceramic blank (10).

3. 3. The method of claim 1 or 2, further comprising the step of heat treating the powder mixture agglomerate (26).

4. 3. The method of claim 1, wherein at least one of the powder of the first material (18) and the powder of the second material (20) comprises rounded glass particles (24), rounded nanoparticles (14), and / or rounded glass-ceramic particles (16).

5. 3. The method of claim 1 or 2, wherein the powder mixture agglomerate (26) is disposed within the mold (22) during compaction of the powder mixture agglomerate (26) by hot pressing.

6. 3. The method of claim 1 or 2, wherein during compression of the powder mixed agglomerate (26) by hot pressing, the powder mixed agglomerate (26) is first heated to a temperature of at least 700°C and then subjected to a compressive force (F).

7. 7. The method of claim 6, wherein the achievement of a temperature of at least 700°C is used as a trigger criterion for applying said compressive force (F).

8. 3. The method according to claim 1 or 2, wherein the powder mixture agglomerate (26) is compressed by hot pressing to a density of at least 99.9% of the base density of the powder of the first material (18) and / or the base density of the powder of the second material (20).

9. 3. The method of claim 1 or 2, wherein the powder of the first material (18) and the powder of the second material (20) are introduced into the mold (22) at at least two separate locations to form at least two powder mixture agglomerates (26).

10. 3. The method according to claim 1 or 2, wherein the powder mixture agglomerate (26) is compressed by hot pressing at a temperature of 650°C to 980°C and a pressure of 5 MPa to 50 MPa.

11. 3. The method of claim 1 or 2, wherein the powder mixture agglomerate (26) is compressed by hot pressing for 0.1 to 10 minutes.

12. 3. The method of claim 1 or 2, wherein the powder mixture agglomerate (26) is compressed by hot pressing under a vacuum of less than 0.1 bar.

13. 3. The method according to claim 1 or 2, wherein the glass-ceramic blank (10) is a multi-layer blank (28).

14. 3. The method of claim 1 or 2, further comprising the step of opening the mold (22) and removing the glass-ceramic blank (10).

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