Selective coloring using coloring solutions in 3D printing

Abstract

To obtain a method and an apparatus for producing a dental restoration (100) by jet-printing, which can improve a multi-color 3D printing method for ceramic slurry using inkjet.SOLUTION: A dental restoration (100) is produced by jet-printing comprising: a step (S101) of jet-printing one layer or a plurality of layers of the dental restoration using a ceramic slurry; and a step (S102) of jet-printing a coloring solution onto the one layer or the plurality of layers.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a method for manufacturing dental prostheses by jet printing and a manufacturing apparatus for manufacturing dental prostheses by jet printing.

Background Art

[0002] Differently colored solvent-based ceramic slurries, such as zirconium dioxide, can be selectively applied in droplet form in a jetting manner (inkjet method) by stacking them vertically one on top of the other to form a number of layers. However, for the processing of highly filled ceramic slurries, high required performance regarding particle size, degree of filling, viscosity, and abrasiveness is required for the printing head used. Inkjet printing (jet) of aqueous ceramic slurries provides an alternative to solvent-based slurries. In that case, the sprayed material layer is dried without cracking.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to improve a multicolor 3D printing method for ceramic slurries using inkjet.

Means for Solving the Problems

[0004] The above technical problems are solved by the subject matter of the independent claims. Technically preferred embodiments are the subject matter of the dependent claims, the detailed description of the invention, and the accompanying drawings.

[0005] According to a first aspect, there is provided a method for manufacturing a dental prosthesis by inkjet printing, the method comprising the steps of inkjet printing one or more layers of a ceramic slurry and inkjet printing a coloring solution onto the one or more layers. Thereby, the technical problem described above is solved. Thereby, the selective slurry application process and the selective coloring process can be separated. The same or different print heads can be used for the application process and the coloring process.

[0006] On the other hand, when slurries that are already pre-colored and have different translucencies and / or different mechanical properties thereon are used, a separate print head is assigned to each of those slurries. On the other hand, according to this method, since the coloring is performed by inkjet printing of a subsequent coloring solution separately from the layer construction, the number of print heads for applying the slurry can be reduced.

[0007] According to a technically preferred embodiment of this method, one or more layers are dried before the coloring solution is inkjet printed. Thereby, for example, technical advantages such as reduced diffusion of the coloring solution and improved local uniformity of the coloring are achieved.

[0008] According to another technically preferred embodiment of this method, the applied coloring solution is fixed by an alkaline solution. The alkaline solution can be applied onto the layer after or before the application of the coloring solution. Thereby, for example, a technical advantage such as preventing the outflow of the coloring solution can be achieved.

[0009] According to another technically preferred embodiment of this method, the ceramic slurry has a basic pH value. Thereby, for example, a technical advantage such as the coloring solution being automatically fixed to the slurry is achieved.

[0010] According to another technically preferred embodiment of this method, the coloring solution is spray-printed onto one or more layers in a wet state. Thereby, for example, a precipitation reaction of the coloring solution occurs, achieving the technical advantage that the process can be executed more quickly.

[0011] According to another technically preferred embodiment of this method, the coloring solution is fixed by contact with the ceramic slurry. Thereby, for example, the technical advantage that this method can be executed more efficiently is achieved.

[0012] According to another technically preferred embodiment of this method, the one or more layers in a wet state are dried together with the applied coloring solution. Thereby, for example, the technical advantage that the next layer can be applied immediately is achieved.

[0013] According to another technically preferred embodiment of this method, the step of manufacturing the dental prosthesis is repeated. Thereby, for example, the technical advantage that the entire dental prosthesis can be constructed and colored is achieved.

[0014] According to another technically preferred embodiment of this method, the dental prosthesis is sintered in a sintering kiln. Thereby, for example, the technical advantage that a dental prosthesis with high strength can be manufactured is achieved.

[0015] According to another technically preferred embodiment of this method, a drying and / or debinding process is performed on the manufactured dental prosthesis before the sintering process. This drying and / or debinding process can be performed in an independent thermal process or in a pre-process step within the sintering process. Usually, drying is performed at a temperature of 25°C to 200°C, more preferably 30°C to 180°C, and most preferably 40°C to 150°C. Additionally in that case, the humidity can be adjusted to 10 to 90%, more preferably 15 to 85%, and most preferably 20 to 80%. Generally, the debinding treatment is performed at a temperature of 50°C to 600°C, more preferably 100°C to 600°C, and most preferably 200°C to 600°C. The heating rate is 0.1 to 10 K / min, more preferably 0.2 to 10 K / min, and most preferably 0.5 to 10 K / min.

[0016] According to a second aspect, the above-described technical problem is solved by a manufacturing apparatus for manufacturing a dental prosthesis by inkjet printing, which has a first print head for inkjet printing one or more layers of a dental prosthesis using a ceramic slurry and a second print head for inkjet printing a coloring solution on the one or more layers. By this manufacturing apparatus, the same technical advantages as the method according to the first aspect described above are achieved.

[0017] According to a technically preferred embodiment of this manufacturing apparatus, the first print head and the second print head are integrated within a common print module. Thereby, for example, the technical advantage that the structure of the manufacturing apparatus is simplified is achieved.

[0018] According to another technically preferred embodiment of this manufacturing apparatus, the first print head and the second print head are controllable independently of each other. Thereby, for example, the technical advantage that the application of the slurry and the coloring solution can be performed independently of each other is achieved.

[0019] According to another technically preferred embodiment of this manufacturing apparatus, the manufacturing apparatus includes a dithering module for calculating an intermediate color value by mixing at least two types of coloring solutions. Thereby, for example, a technical advantage that the natural appearance of the dental prosthesis is further improved is achieved.

[0020] According to another technically preferred embodiment of this manufacturing apparatus, the dithering module is configured to use different two-dimensional dithering patterns in the layers continuous above and below the dental prosthesis. Thereby, for example, a technical advantage that the generation of stripe or ripple patterns in the dental prosthesis is prevented is achieved.

[0021] According to a third aspect, a manufacturing apparatus for manufacturing a dental prosthesis by inkjet printing; at least one type of ceramic slurry for inkjet printing one layer or a plurality of layers of the dental prosthesis; and a coloring solution for inkjet printing on the one layer or the plurality of layers, the above-described technical problem is solved by an inkjet printing system. By this inkjet printing system, the same technical advantages as the method according to the first aspect described above are achieved.

[0022] According to a technically preferred embodiment of this inkjet printing system, at least one type of ceramic slurry and / or coloring solution is stored in a storage tank. Thereby, for example, a technical advantage that the ceramic slurry and / or coloring solution can be reliably stored is achieved.

[0023] According to another technically preferred embodiment of this inkjet printing system, the storage tank is replaceable. Thereby, for example, a technical advantage that the solution can be easily changed is achieved.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0025] Next, embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] In FIG. 1, different parts of the tooth 105 are shown. The tooth 105 has an inner dentin core 101 and an outer enamel 103. An optional intermediate region 115 exists between the dentin core 101 and the enamel 103, and a specific selection of the ceramic slurry 109 and the coloring solution 107 can be assigned to that intermediate region.

[0027] For the basic coloring of the tooth 105, a cloudy color, that is, an opaque dentin core 101, is required. That dentin core 101 is visible through the incisal enamel 103. The enamel 103 is essentially visible, that is, translucent. Translucent means partial light transmissibility of an object. In order to make the dental prosthesis have an appearance as natural as possible, the above structure of the tooth 105 is also applied to an artificial dental prosthesis. Therefore, materials having various optical properties are used in the manufacture of dental prostheses.

[0028] Figure 2 schematically shows a dental prosthesis 100. The dental prosthesis 100 functions as a denture and is formed, for example, as a bridge, crown, veneer, inlay, onlay, abutment, partial or complete denture. The dental prosthesis 100 is constructed, for example, using different ceramic slurries 109. The ceramic slurry contains partially stabilized ZrO 2 and / or Al 2 O 3 particles. Al 2 O 3 can be incorporated in advance in the same way as the stabilizing ions. Partial stabilization is generally carried out by incorporating CaO, MgO, Y 2 O 3 , La 2 O 3 , or CeO 2 , as well as mixtures thereof, into ZrO 2 . A preferred embodiment contains Y 2 O 3 in a range of 1 to 10 mol%, more preferably in a range of 2 to 8 mol%, and most preferably in a range of 2.5 to 6 mol% as a stabilizer. Therefore, when the dental prosthesis 100 is three-dimensionally manufactured by an inkjet printing method, such a slurry 109 is selectively used in the corresponding regions.

[0029] The dental prosthesis 100 is formed from successive layers printed one on top of the other. In that case, the ceramic powder of the slurry 109 can be supplied in advance with a predetermined translucency. By mixing the slurry 109, the target translucency of the dental prosthesis 100 in the corresponding spatial region is obtained.

[0030] After selectively applying a layer of the slurry 109 by an inkjet printing method, the layer is dried without cracking by evaporating water or a solvent as a binder. What remains is a porous white body layer, which has a layer thickness of 1 μm to 50 μm and a density of at least 2.5 g / cm 3 . This process is repeated until the entire dental prosthesis 100 is three-dimensionally constructed layer by layer.

[0031] ZrO 2 In the case of slurry 109, ceramic powders doped with different amounts of yttrium (3 mol% yttrium - 3Y - TZP, 4 mol% yttrium - 4Y - TZP, 5 mol% yttrium - 5Y - TZP) can be used for different strengths.

[0032] 3Y - TZP = low translucency / high strength 4Y - TZP = medium translucency / medium strength 5Y - TZP = high translucency / low strength

[0033] On the other hand, when using slurries 109 that are pre - colored differently and all have different translucencies and / or mechanical properties, a unique print head 111 - 1 is assigned to each of those slurries 109. For example, when using a 4 - color color scheme such as the common CMKY (cyan, magenta, yellow, key plate) to cover the entire color space and apply slurries with different translucencies or strengths in three patterns, 3×4 = 12 slurries 109 are included in 12 print heads. Manufacturing these different slurries 109 is also complex. Those numerous slurries 109 are maintained and managed as different items.

[0034] Figure 3 shows a schematic diagram of a manufacturing apparatus 200 for manufacturing a dental prosthesis 100 by inkjet printing of an aqueous or solvent - based slurry 109. The base slurry 109 is processed to fabricate a multi - material and multi - color dental prosthesis 100 made of ceramic by an additive method using inkjet printing.

[0035] The manufacturing apparatus 200 includes a plurality of storage tanks 119-1 that contain a base slurry 109 and a carrier material 110, each having different optical characteristics. In addition, the manufacturing apparatus 200 includes at least a plurality of storage tanks 119-2 that contain a coloring solution 107 and an alkaline solution 108 for fixing the coloring solution. A manufacturing apparatus for manufacturing a dental prosthesis by inkjet printing; at least one type of ceramic slurry; and a coloring solution for inkjet printing constitute an inkjet printing system as a combination.

[0036] In order to three-dimensionally construct the dental prosthesis 100 layer by layer, the ceramic slurries 109 are applied in droplets as a plurality of layers 117-1, ···, 117-n using a print head 111-1 to which each of the ceramic slurries 109 is assigned. The print head 111-1 is operable in two directions and thus can print the slurry 109 at any position. The slurry 109 is typically used with a droplet volume of 10 to 100 picoliters for selective material application, thereby omitting the time-consuming debinding process. For ejecting the droplets, for example, an electrically controlled piezoelectric element is used. It is also possible to use bubble jet technology for ejecting the droplets of the slurry. To apply the carrier material 110, at least one other print head 111-3 that can selectively apply the carrier material 110 is used.

[0037] At least one other print head 111-2 is used to apply the coloring solution 107, and the print head can inkjet print the coloring solution 107 onto one or more layers 117-1, ···, 117-n. The print head 111-2 can also operate in two directions and thus can print the coloring solution 107 at any position.

[0038] Optionally, at least one additional print head 111-4 is used to apply an alkaline solution 108 for fixing the coloring solution 107, and the alkaline solution 108 can be inkjet printed onto one or more layers 117-1, ···, 117-n by the print head. The print head 111-4 can also operate in two directions and thus can print the alkaline solution 108 at any position. The print heads 111-1, 111-2, 111-3 and 111-4 can be controllable independently of each other or integrated within a common printing module.

[0039] The manufacturing apparatus 200 provides a reduced number of pre-colored and yttrium-doped neutral base slurries 109 in order to minimize the number of print heads 111-1 and 111-2 and nevertheless achieve the aesthetics and functionality of the dental prosthesis 100. The final coloring is performed separately by selective application of the coloring solution 107.

[0040] Different coloring solutions 107 are combined to mix the required tooth color. In that case, a subtractive color system, which is over a limited dental color space (dental color gamut), is used. Thus, color synthesis, three-dimensional halftoning or dithering of those coloring solutions 107 in different ratios is created within a limited dental color space (color gamut) that covers common tooth colors but not all colors.

[0041] In that case, different coloring solutions 107 are selectively applied onto layers 117-1, ···, 117-n according to a 3D dithering algorithm executed by a dithering module 113. Therefore, the dithering module 113 includes a processor for executing the 3D dithering algorithm and digital data storage for storing the calculated mixing ratio and the dithering algorithm. The processor includes any hardware system, component, or mechanism for processing data, signals, or other information. The processor can include a central data processing unit (CPU), a system having a plurality of data processing units (MPU), a dedicated electric circuit for executing functions, and other systems. The data storage can include a hard disk, a flash memory card, a random access memory (RAM), or a read only memory (ROM).

[0042] During dithering, various coloring solutions are selectively applied within a printing plane in a specific ratio and a two-dimensional printing pattern using an inkjet printing method. In addition, the 3D dithering algorithm calculates so that non-identical two-dimensional dithering patterns are applied one above the other within a plurality of layers 117-1, ···, 117-n. Thereby, in the case of a vertical surface, an optical effect such as, for example, a stripe or a ripple pattern can be prevented. Color synthesis, three-dimensional halftoning, or dithering of the coloring solution 107 at different ratios is generated within the range of a limited dental color space (color gamut), which covers general tooth colors but not all colors in general.

[0043] When using a slurry 109 with a high viscosity exceeding 100 mPas at a high filling rate, extremely high required performance is demanded for a printing head 111-1 and its fluid system. To prevent incompatibility and its effects, such as corrosion on the printing head, the binder used for the printing head 111-1 and / or the carrier material of the slurry 109, for example, in the case of an aqueous slurry, is made to be compatible with water.

[0044] After selectively applying the slurry 109 to one layer 117-1, ···, 117-n using an inkjet printing method, the layer 117-1, ···, 117-n is dried without cracking by evaporating water or a solvent as a binder. In that case, the ceramic powder of the slurry 109 can be pre-colored in a predetermined color, for example, in a basic color or a tooth color. What remains is a porous white body layer having a layer thickness of 1 μm to 50 μm and a density of at least 2.5 g / cm 3 and is. The process is repeated until the entire dental prosthesis 100 is three-dimensionally constructed layer by layer.

[0045] When two types of slurries 109 having different translucencies are available, a high-hardness and opaque slurry 109 can be used for the dentin core, and a normal-hardness and highly translucent slurry 109 can be used for the enamel. Selective coloring is performed by selectively inkjet-printing a coloring solution such as a nitrate solution (acid) according to an appropriate color code or color information after the material application of each of the first to nth layers 117-1, ···, 117-n.

[0046] FIG. 4 shows an outline of a method for manufacturing a dental prosthesis 100 by inkjet printing. In step S201, first, selective material application of the slurry 109 for each layer using an inkjet printing method (inkjet method) is performed. In step S202, the applied slurry layer is dried, for example, by adding hot air. In step S203, the layers 117-1, ···, 117-n (green body layers) of the applied slurries 109 from the first to the nth are selectively colored with a coloring solution. In that case, the coloring solution is also printed on the layers 117-1, ···, 117-n of the applied slurries 109 from the first to the nth by inkjet printing. In step S204, the printed coloring solution is locally fixed using an alkaline solution 108, that is, an alkaline solution having a pH value of more than 7. Then, steps S201 to S204 are repeated until the dental prosthesis 100 is completely three-dimensionally constructed.

[0047] For this method, an aqueous or solvent-based slurry 109 can be processed. In that case, selective material application (step S201) and selective coloring (step S203) are performed separately.

[0048] FIG. 5 shows an overview of another method for manufacturing a dental prosthesis 100 by inkjet printing. In step S301, first, selective material application for each layer of the basic slurry 109 is performed using an inkjet printing method.

[0049] The basic slurry 109 has a pH value above 7. A typical basic slurry 109 contains H 2 2O and, for example, 0 to 5 wt%, preferably 0.01 to 5 wt% of a carboxylic acid derivative (citric acid) or 0 to 5 wt%, preferably 0.01 to 5 wt% of ammonium polyacrylate (NH 4 4PAA) and other dispersion aids. The pH value (8 - 11) can be adjusted by NH 4 4OH. Such basic adjustment of the slurry 109 has the technical advantage that the erosiveness of the ceramic slurry 109 with respect to the corrosion of the metal parts of the print head is reduced.

[0050] In addition, in order to adjust the viscosity and / or sedimentation characteristics, the slurry can contain a small amount, for example, 0 to 5 wt%, preferably 0.001 to 5 wt% of a thickener such as polyvinylpyrrolidone, cellusol derivatives, or xanthan gum. Sedimentation characteristics are those that cause the suspension to be stable over a long time and prevent sedimentation.

[0051] In step S302, the layers 117-1, ···, 117-n (green body layers) of the wet and undried applied slurry 109 are selectively colored by a coloring solution. In that case, when the coloring solution (nitrate) contacts the wet slurry 109, a precipitation reaction occurs simultaneously. Ions of the dissolved 3d and 4f elements precipitate as hydroxides due to the pH shift upon contact with the wet layer. In that case, for example, Fe(OH) 3 or Er(OH) 3 is produced.

[0052] In step S303, the coloring solution is automatically fixed by contact with the basic slurry 109. In step S304, the layers 117-1, ···, 117-n, which are in a wet state and colored by the wet material, are dried without cracks, for example, by supplying hot air. Thereafter, steps S301 to S304 are repeated until the dental prosthesis 100 is completely three-dimensionally constructed.

[0053] For this method, an aqueous or solvent-based slurry 109 can be processed. In that case, selective material application (step S301) and selective coloring (step S302) are performed separately.

[0054] FIG. 6 shows a table summarizing the compositions of different coloring solutions 107. The coloring solution 107 has a low viscosity and can be inkjet printed using a drop-on-demand or bubble jet inkjet printing head. A plurality of color channels can be incorporated in the printing head for multicolor printing. The printing head can apply the coloring solution onto the layers 117-1, ···, 117-n at a high resolution of 720 dpi or higher.

[0055] When 6 printing heads are available, only 1 printing head is used for the slurry 109 with intermediate translucency, and 1 printing head is used for the carrier material 110. When 7 printing heads are available, 2 printing heads are used for the opaque slurry 109 and the highly translucent slurry 109 respectively, and 1 printing head is used for the carrier material 110. In either case, the other 4 printing heads are used for the coloring solution 107.

[0056] The coloring solution 107 is an aqueous-based nitrate or chloride salt solution. In the coloring solution 107, various metal salts (e.g., Fe(NO 3 ) 3 ·9H 2 O; Pr(NO 3 ) 3 ·6H 2 O; Tb(NO 3 ) 3 ·5H 2 O; Er(NO 3 ) 3 ·5H 2 O; Mn(NO 3 ) 2 ·4H 2 O; Co(NO 3 ) 2 ·6H 2 O; Cr(NO 3 ) 3 ·9H 2 O; Mg(NO 3 ) 2 ·6H 2 O; Al(NO 3 ) 3 ·9H 2 O; Cu(NO 3 ) 2 ·3H 2 O; Zn(NO 3 ) 2 ·6H 2 O; Y(NO 3 ) 3 ·6H 2 O; La(NO 3 ) 3 ·6H 2 O; Ce(NO 3 ) 3 ·6H 2 O; Nd(NO3 ) 3 ·6H 2 O; Sm(NO 3 ) 3 ·6H 2 O; Gd(NO 3 ) 3 ·6H 2 O; Yb(NO 3 ) 3 ·6H 2 O; Ni(NO 3 ) 2 ·6H 2 O; Co(NO 3 ) 2 ·6H 2 O; Ga(NO 3 ) 3 ·xH 2 O; In(NO 3 ) 3 ·xH 2 O) are dissolved at different concentrations. The concentration depends on the required color intensity but is assumed not to exceed the solubility limit of the salt. However, the coloring solution 107 can also be made significantly higher in concentration depending on the required composition. However, as the ion concentration increases, the viscosity increases or the pH value moves into the acidic region (<7). An increase in the viscosity of the coloring solution is advantageous for reducing the penetration depth or diffusion depth of the coloring solution into the dried layer.

[0057] Water and nitric acid (HNO 3 ) can be used as the basic acid. Therefore, four types of nitrate solutions (Fe(NO 3 ) 3 ·9H 2 O; Er(NO 3 ) 3 ·5H 2 O; Cr(NO 3 ) 3 ·9H 2 O; Mn(NO 3 ) 2 ·4H 2 O; Tb(NO 3 ) 3 ·5H 2 O and Pr(NO 3 ) 3 ·6H 2Only (O) is used as the coloring solution 107 to create the tooth color. In the minimum case, only three nitrate solutions (Fe - yellow, Er - pink, Cr - gray) are required. Other salts function for fine color adjustment.

[0058] In addition, the opacity of the slurry 109 of the dental prosthesis 100 can be adjusted by the variable components of yttrium or ytterbium in the coloring solution. For example, components such as yttrium, ytterbium, neodymium, and europium are used as translucency enhancers, and aluminum and silicon are used as opaque liquids. The yttrium content can be increased using an appropriate coloring solution. Thereby, different opacity values can be achieved in the dental prosthesis 100, for example, providing opacity for the dentin core and translucency for the enamel.

[0059] Figure 7 shows a block diagram of a method for manufacturing a dental prosthesis 100 by inkjet printing. In step S101, one or more layers 117 - 1, ···, 117 - n of the dental prosthesis 100 are inkjet printed using the ceramic slurry 109. Then, in step S102, the coloring solution 107 is inkjet printed onto the layers 117 - 1, ···, 117 - n.

[0060] When the penetration depth of the coloring solution 107 is greater than the layer thickness of the individual layers 117 - 1, ···, 117 - n, coloring can be performed for the first time after multiple layer coatings of the slurry 109. In addition, the penetration or diffusion depth of the coloring solution 107 can be controlled through viscosity adjustment. This is achieved by adding an appropriate thickening agent that is stable in the pH range of the coloring solution. A suitable thickening agent is, for example, polyvinylpyrrolidone (PVP). To achieve a process that is as stable as possible, the penetration or diffusion depth of all coloring solutions used can be made uniform.

[0061] Since the slurry 109 and the coloring solution 107 have diverse hydrodynamic characteristics, it is effective to use diverse print head technologies. The slurry 109 has a high viscosity (10 to 1000 mPas depending on the shear rate) and contains a frictional filler in the form of ceramic particles or the like at a high weight / volume ratio. A slurry 109 with a low viscosity of 10 to 500 mPas is preferred, and a viscosity of 10 to 100 mPas is even more preferred. The higher the viscosity of the slurry 109, the more difficult it is to process with an inkjet print head based on MEMS technology.

[0062] In contrast, the coloring solution 107 has a low viscosity (0.5 to 50 mPas). In addition, the amounts to be processed respectively are different, and in terms of the component ratio, the slurry 109 is about 98% while the coloring solution 107 is about 2%. The main volume is processed with respect to the slurry 109, while the coloring solution 107 is processed in a smaller volume. The coloring solution 107 and the slurry 109 can be stored in storage tanks 119-1 and 119-2 of different sizes respectively.

[0063] The inkjet printing of the coloring solution 107 can be carried out after the drying of the coated layers 117-1, ···, 117-n, or can be carried out on the still wet layers 117-1, ···, 117-n (wet-on-wet). When inkjet printing the coloring solution 107 on the dried layers 117-1, ···, 117-n, it is necessary to be able to control the depth of penetration of the coloring solution 107.

[0064] Thereafter, the fully constructed dental prosthesis 100 is sintered in a sintering furnace. The slurry 109 in combination with the coloring solution 107 can be adjusted to have uniform sintering characteristics. By adjusting the coloring solution 107, the sintering kinetics can be uniformly adjusted.

[0065] The adjustment of the sintering characteristics of the individual layers can be carried out by adding a sintering activator or a sintering inhibitor to the coloring solution according to the purpose. The sintering activator is, for example, Zn 2 + ions, Al 3+ ions, or Mg 2 + ions, such as Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, or Mg(NO 3 )·H 2 O, etc., can be added to the coloring solution. The sintering inhibitor is, for example, La 3 + ions or Y 3 + ions, such as La(NO 3 ) 3 ·9H 2 O or Y(NO 3 ) 3 ·6H 2 O, etc., can be added to the coloring solution.

[0066] All features described and illustrated in connection with the individual embodiments of the present invention can be the subject of the present invention in various combinations, thereby achieving effective advantages simultaneously.

[0067] All method steps can be carried out using an apparatus suitable for carrying out each method step. All functions carried out by the features in question can be method steps in this method.

[0068] The protection scope of the present invention is defined by the appended claims and is not limited by the features described or illustrated in the description.

Explanation of reference numerals

[0069] 100 Dental prosthesis 101 Dentin core 103 Enamel 105 Tooth 107 Coloring solution 108 Alkaline solution 109 Slurry 110 Carrier material 111 Printing head 113 Dithering module 115 Intermediate region 117 Layer 119 Storage tank

Claims

1. jet printing one or more layers of a dental prosthesis with the ceramic slurry; jet printing a colored solution onto said layer or layers. A method for producing a dental prosthesis by jet printing.

2. 10. The method of claim 1, wherein the layer or layers are dried before jet printing the pigmented solution.

3. 3. The method according to claim 1 or 2, wherein the applied colouring solution is fixed by an alkaline solution.

4. 4. The method of claim 1, wherein the ceramic slurry has a basic pH value.

5. 5. The method of claim 4, wherein the coloring solution is fixed by contact with a ceramic slurry.

6. 6. A method according to claim 4 or 5, characterized in that the wet layer or layers are dried together with the applied colour solution.

7. 7. A method according to any one of claims 1 to 6, wherein the steps of producing a dental prosthesis are carried out iteratively.

8. 8. The method according to claim 1, wherein the produced dental prosthesis is subjected to a drying and / or debinding step prior to the sintering process.

9. 9. A method according to any one of claims 1 to 8, comprising sintering a dental prosthesis in a sintering kiln.

10. a first print head for jet printing one or more layers of a dental prosthesis with a ceramic slurry; a second print head for jet printing a coloring solution onto said layer or layers. A manufacturing device that produces dental prostheses by jet printing.

11. 11. The apparatus of claim 10, wherein the apparatus comprises a storage tank for the slurry and a storage tank for the coloring solution.

12. 12. The manufacturing apparatus of claim 10 or 11, wherein the first print head and the second print head are integrated within a common printing module.

13. 13. The manufacturing apparatus according to claim 10, wherein the first print head and the second print head are controllable independently of each other.

14. 14. The manufacturing apparatus according to any one of claims 10 to 13, wherein the manufacturing apparatus comprises a dithering module for calculating intermediate color values ​​by mixing at least two colored solutions.

15. 14. The apparatus of claim 13, wherein the dithering module is configured to use different two-dimensional dithering patterns in successive layers above and below the dental prosthesis.

16. A manufacturing apparatus for manufacturing dental prostheses by jet printing; at least one ceramic slurry for jet printing one or more layers of a dental prosthesis; having a coloring solution for jet printing onto said layer or layers. Jetting printing system.

17. The jetting printing system of claim 16, wherein at least one of the ceramic slurry and / or the coloring solution is stored in a storage tank.

18. 20. The jetting printing system of claim 17, wherein the storage tank is replaceable.

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