Fixation of coloring solution in multi-color ink jet 3D ceramic printing

Abstract

To obtain a method and an apparatus for producing a dental restoration by jet-printing, which can prevent uncontrolled diffusion or running of nitrate salt solutions selectively applied as coloring solutions during a spatial layer build-up process.SOLUTION: A dental restoration 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; a step (S102) of jet-printing a coloring solution onto the one layer or the plurality of layers; and a step (S103) of applying a fixing solution for fixing the coloring solution.SELECTED DRAWING: Figure 7

Description

Technical Field

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

Background Art

[0002] When manually coloring a ceramic prosthesis made of zirconium dioxide, a penetration solution composed of nitrate is used for individual coloring. The penetration solution is applied to the surface of the prosthesis using, for example, a brush and then diffused into the porous ceramic. This application requires a high level of experience of a dental technician.

[0003] This coloring process with zirconium dioxide in its white state can be automated by computer control using an airbrush system to penetrate the prosthesis. In additive manufacturing methods, differently colored solvent-based ceramic slurries can be selectively applied by inkjet. High performance requirements regarding particle size, degree of filling, as well as viscosity and abrasiveness are required for the printing head used for the processing of highly filled ceramic slurries. Inkjet printing (jet) of aqueous slurries provides an alternative to solvent-based slurries. In that case, the sprayed material layer dries without cracking.

[0004] However, during the manual penetration process, the salt solution diffuses uncontrollably into the zirconium dioxide white material. During layer-by-layer selective coloring combined with layer-based material application of a pre-applied ceramic layer, the nitrate deposited earlier in the underlying layer dissolves again and rediffuses uncontrollably into the already processed ceramic member.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of the present invention is to prevent the uncontrollable diffusion or flow of a nitrate solution that is selectively applied as a coloring solution during a three-dimensional layer forming process.

Means for Solving the Problems

[0006] 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.

[0007] 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 onto a dental prosthesis; inkjet printing a coloring solution onto the one or more layers; and applying a fixing solution for fixing the coloring solution. Thereby, it is possible to prevent the nitrate solution selectively applied as the coloring solution from uncontrollably diffusing or flowing during the layer forming process. During the additive manufacturing process, it is ensured that the three-dimensionally printed green body is controllably and selectively colored using the coloring solution. In that case, selective slurry material application and selective coloring are performed separately. The same or different print heads can be used for material application and coloring. The fixing solution prevents the diffusion of the coloring solution, for example, on an aqueous slurry for manufacturing a multi-color green body. In this way, for example, controlled selective coloring is ensured using the coloring solution of the three-dimensionally printed zirconium dioxide green body during the additive manufacturing process.

[0008] According to a technically preferred embodiment of this method, the fixing solution is sprayed onto one or more layers. Thereby, for example, the technical advantage of being able to apply the fixing solution at high speed and over a large area is achieved.

[0009] According to another technically preferred embodiment of this method, a fixing liquid is jet-printed onto one or more layers using a printing head. Thereby, for example, a technical advantage is achieved in that the fixing liquid can be precisely and selectively applied as desired.

[0010] According to another technically preferred embodiment of this method, one or more layers are dried before or after jet-printing the coloring solution. Thereby, for example, a technical advantage is achieved in that the diffusion of the coloring solution is reduced.

[0011] According to another technically preferred embodiment of this method, one or more layers are dried before or after applying the fixing liquid. Thereby, for example, a technical advantage is also achieved in that the diffusion of the coloring solution is reduced.

[0012] According to another technically preferred embodiment of this method, the pH value of the fixing liquid is set to be greater than 7. Thereby, for example, a technical advantage is achieved in that the flow of the coloring solution is effectively reduced.

[0013] According to another technically preferred embodiment of this method, the fixing liquid is an ammonium chloride solution. Thereby, for example, a technical advantage is achieved in that the coloring solution is locally fixed.

[0014] According to another technically preferred embodiment of this method, each of the above steps for manufacturing a dental prosthesis is repeatedly performed. Thereby, for example, a technical advantage is achieved in that the entire dental prosthesis can be constructed and colored.

[0015] According to another technically preferred embodiment of this method, the dental prosthesis is fired in a firing kiln. Thereby, for example, a technical advantage is achieved in that a dental prosthesis with high strength can be manufactured.

[0016] According to a second aspect, there is provided a manufacturing apparatus for producing a dental prosthesis by inkjet printing, comprising: a first print head for inkjet printing one or more layers of a dental prosthesis using a ceramic slurry; a second print head for inkjet printing a coloring solution onto the one or more layers; and an application device for applying a fixing solution for fixing the coloring solution. By this manufacturing apparatus, the above-described technical problem is solved. By this manufacturing apparatus, technical advantages similar to those of the method according to the first aspect described above are achieved.

[0017] According to a technically preferred embodiment of this manufacturing apparatus, the application device is constituted by a spray head for applying the fixing solution in a planar manner. Thereby, for example, a technical advantage that the fixing solution can be applied rapidly and over a large area is achieved.

[0018] According to another technically preferred embodiment of this manufacturing apparatus, the application device is constituted by a print head for selectively applying the fixing solution. Thereby, for example, a technical advantage that the fixing solution can be selectively applied according to a target is achieved.

[0019] According to another technically preferred embodiment of this manufacturing apparatus, the manufacturing apparatus includes a storage tank for the fixing solution. The storage tank can be made replaceable. Thereby, for example, a technical advantage that the fixing solution can be stored and used conveniently is achieved.

[0020] According to another technically preferred embodiment of this manufacturing apparatus, the manufacturing apparatus includes a drying device for drying the applied materials such as, for example, a slurry layer, a coloring solution, and a fixing solution. Thereby, for example, a technical advantage that additional diffusion can be reduced is achieved.

[0021] According to another technically preferred embodiment of this manufacturing apparatus, the drying device includes a blower and / or an infrared radiation device. Thereby, for example, a technical advantage that the layer can be dried rapidly is achieved.

[0022] According to a third aspect, a manufacturing apparatus for manufacturing a dental prosthesis by inkjet printing; a coloring solution for printing on one or more layers; and a fixing solution for fixing the coloring solution are provided, and the above 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.

[0023] According to a technically preferred embodiment of this inkjet printing system, the coloring solution and / or the fixing solution are stored in a tank. Thereby, for example, the technical advantage of being able to reliably store each solution is achieved.

[0024] According to another technically preferred embodiment of this inkjet printing system, the tank is replaceable. Thereby, for example, the technical advantage of being able to easily replace the solution is achieved.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0026] Next, embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] FIG. 1 shows different parts of a tooth 105. The tooth 105 has an inner dentin core 101 and an outer enamel 103. For the basic coloring of the tooth 105, a turbid color, i.e., an opaque dentin core 101, is required. The dentin core is visible through the incisal enamel 103. The enamel 103 is essentially transparent, i.e., translucent. Translucent means partial light transmissibility of an object. To make the dental prosthesis as natural-looking as possible, the above structure of the tooth 105 is also applied to artificial dental prostheses. Therefore, materials with various optical properties are used in the manufacture of dental prostheses.

[0028] FIG. 2 schematically shows a dental prosthesis 100. The dental prosthesis 100 functions as a denture and is formed, for example, as a bridge, crown, partial or complete denture. The dental prosthesis 100 is selectively constructed layer by layer using an inkjet printing method from, for example, 1 to n different ceramic slurries 109, for example Fe 2 O 3 , Cr 2 O 3 , Mn 2 O 3 , Tb 2 O 3 , Pr 2 O 3 , Er 2 O 3 , Co 3 O 4 , NiO, TiO 2 , CeO 2 etc. are selectively colored layer by layer using nitrates, and / or doped using yttrium etc., and then the white body of the dental prosthesis 100 thus obtained is fired so as to obtain appropriate properties regarding color, translucency, opacity, and mechanical properties.

[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 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 layer having a layer thickness of 1 μm to 50 μm and a density of at least 2.5 g / cm 3 . The process is repeated until the entire dental prosthesis 100 is built up layer by layer in three dimensions.

[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) to have different hardnesses can also be used. In that case, yttrium doping can also be a factor in the difference in translucency. The differently yttrium - doped ceramic powders have different properties. 3Y - TZP = low translucency / high hardness 4Y - TZP = medium translucency / medium hardness 5Y - TZP = high translucency / low hardness

[0032] On the other hand, when using slurries 109 that are differently pre - colored and all have different translucencies and / or mechanical properties, a dedicated print head 111 - 1 is assigned to each of those slurries 109. For example, when using a common CMYK color scheme to cover the entire color space, 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.

[0033] FIG. 3 shows a schematic view of a manufacturing apparatus 200 for manufacturing a dental prosthesis 100 by inkjet printing (ink - jet printing) of an aqueous or solvent - based slurry 109. The base slurry 109 is processed to additively manufacture a multi - material and multicolor dental prosthesis 100 made of ceramic by inkjet printing.

[0034] The manufacturing apparatus 200 includes a plurality of storage tanks 119-1 in which base slurries 109 having different optical characteristics are accommodated. In addition, the manufacturing apparatus 200 includes at least a plurality of storage tanks 119-2 in which the coloring solution 107 is accommodated. Additionally, the manufacturing apparatus 200 includes a storage tank 119-3 in which the fixing solution 115 is accommodated.

[0035] A manufacturing apparatus for manufacturing a dental prosthesis by inkjet printing; a coloring solution for printing on one or more layers; and a fixing solution for fixing the coloring solution constitute an inkjet printing system as a combination.

[0036] In order to three-dimensionally construct the dental prosthesis 100 layer by layer, the ceramic slurry 109 is applied as a plurality of layers 117-1, ···, 117-n in the form of droplets using a print head 111-1 to which the ceramic slurry 109 is allotted. The print head 111-1 is operable in two directions and thus can print the slurry 109 at any position. It is also possible to arrange the print head immovably and operate the construction platform in three spatial directions below the print head.

[0037] The slurry 109 is usually 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.

[0038] Another print head 111-2 is used to apply the coloring solution 107, and the print head can jet-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, so that the coloring solution 107 can be printed at any position. The print heads 111-1 and 111-2 can be controlled independently of each other or integrated into a common printing module. The print heads 111-1 and 111-2 can also be arranged immovably, and the construction platform can be operated in three spatial directions below the print heads.

[0039] The fixing solution 115 is applied by another coating device 121 that can be formed by a spray head for applying the fixing solution 115 in a planar manner or an additional print head for selectively applying the fixing solution 115.

[0040] A drying device 123 is provided to dry the aqueous material, so that the layers 117-1, ···, 117-n, the coloring solution 107, and the fixing solution 115 can be dried without cracking. The drying device 123 can be constituted by, for example, a blower and / or an infrared irradiation device.

[0041] The manufacturing device 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 still achieve the aesthetics and functionality of the dental prosthesis 100. The coloring is performed by separately selectively applying the coloring solution 107.

[0042] The required tooth color is mixed by combining the already pre-colored coloring solutions 107. In that case, a subtractive color system, which covers a limited dental color space (dental color gamut), is used. Therefore, color synthesis, three-dimensional halftoning, or dithering of the slurries 109 pre-colored in different ratios is created within a limited dental color space (color gamut) that covers all common tooth colors but not all colors.

[0043] In that case, different coloring solutions 107 are selectively applied onto layers 117-1, ···, 117-n according to a 3D dithering algorithm executed by the dithering module 113. Therefore, the dithering module 113 includes a processor for executing the 3D dithering algorithm and a digital memory 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 with multiple data processing units (MPU), a dedicated electric circuit for executing functions, and other systems. The data memory can include a hard disk, a flash memory card, a random access memory (RAM), or a read-only memory (ROM).

[0044] During dithering, various coloring solutions are selectively applied within the 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, optical effects such as, for example, stripe or ripple patterns can be prevented. Color synthesis, three-dimensional halftoning, or dithering of pre-colored slurries 109 with different ratios are generated within the range of a limited dental color space (color gamut), which covers general tooth colors but not all colors in general.

[0045] When using a slurry 109 with a high viscosity exceeding 100 mPas at a high filling rate, extremely high required performance is demanded for the print head 111-1 and its fluid system. To prevent incompatibility and its effects, such as corrosion on the print head, the print head 111-1 is made to be compatible with the binder used and / or the carrier material of the slurry 109.

[0046] 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 already colored in a predetermined color, for example, colored in a basic color or a tooth color. What remains is a porous white layer having a layer thickness of 1 μm to 50 μm and a density of at least 2.5 g / cm 3 and. The process is repeated until the entire dental prosthesis 100 is three-dimensionally constructed layer by layer.

[0047] When two types of slurries 109 having different translucencies can be used, a slurry 109 with high hardness and opacity can be used for the dentin core, and a slurry 109 with normal hardness and high translucency 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 is performed.

[0048] 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 to the 1-nth layer 117-1, ···, 117-n using an inkjet printing method (inkjet method) is performed.

[0049] In step S202, for example, the applied slurry layer is dried by the addition of hot air. In step S203, the layers 117-1, ···, 117-n (green body layers) of the applied slurry 109 from the 1st 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 slurry 109 from the 1st to the nth by inkjet printing. In step S204, the printed coloring solution is locally fixed using a fixing solution, that is, an alkaline liquid (alkali solution) having a pH value of more than 7. Thereafter, steps S201 to S204 are repeated until the dental prosthesis 100 is completely three-dimensionally constructed.

[0050] 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. Such a process has the technical advantage that the pH value of the coloring solution has little effect on the dried, that is, anhydrous layers 117-1, ···, 117-n.

[0051] Fig. 5 shows an outline of another method for manufacturing the dental prosthesis 100 by inkjet printing. In step S301, first, selective material application for each layer of the basic slurry 109 to the 1-nth layer is performed using an inkjet printing method.

[0052] The basic slurry 109 has a pH value of more than 7. A normal basic slurry 109 contains H 2 O 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 PAA) and other dispersion aids. The pH value (8-11) can be adjusted by NH 4 OH. Such adjustment of the basicity 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.

[0053] 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 nitrate (coloring solution) contacts the wet slurry 109, a precipitation reaction occurs simultaneously.

[0054] 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 that are wet and colored by the wetting agent 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.

[0055] 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.

[0056] When a basic slurry 109 is not used, the coloring solution 107 diffuses into the layers 117-1, ···, 117-n. Fixing of the applied coloring solution is performed by independent application of a fixing solution, for example, an alkaline solution.

[0057] In this process, the slurry 109 is stabilized in the acidic pH value region. After each individual layer is printed and dried, first, a basic fixing solution such as a 0.1N ammonium hydroxide solution is applied. Thereafter, the coloring solution 107 is applied. When the coloring solution contacts the layer treated with the fixing solution, the pH value of the coloring solution locally changes in the direction of pH>2. Due to this change in the pH value of the coloring solution, metal hydroxides such as Fe(OH) 3 etc. are locally formed at the locations where the coloring solution should be fixed. This process is referred to as precipitation or coagulation.

[0058] After printing and drying each individual layer, a coloring solution and immediately thereafter a basic fixing solution can also be applied, and the fixing solution also fixes the coloring component at the required positions in the same manner.

[0059] Figure 6 shows a table summarizing the compositions of different coloring solutions 107. The coloring solution 107 has a low viscosity and can be jet-printed using an inkjet printing head of the drop-on-demand type or the bubble jet type. A plurality of color channels can be incorporated in the printing head for multicolor printing. The printing head can apply the coloring solution onto layers 117-1, ···, 117-n at a high resolution of 720 dpi.

[0060] When 6 printing heads are available, only 1 printing head is used for the slurry 109 having intermediate translucency, and 1 printing head is used for the carrier material. 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. In either case, the other 4 printing heads are used for the coloring solution 107.

[0061] The coloring solution is an aqueous-based nitrate or chloride salt solution. Therefore, 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(NO 3 ) 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.

[0062] However, the coloring solution 107 can also be made significantly higher in concentration according to the required composition. However, as the ion concentration increases, the viscosity increases or the pH value moves into the acidic region (<7).

[0063] FIG. 7 shows a block diagram of a method for manufacturing a dental prosthesis 100 by inkjet printing. In step S101, layers 117-1, ···, 117-n of the dental prosthesis 100 are inkjet printed using a ceramic slurry 109. In step S102, a coloring solution 107 is inkjet printed onto one or more of the layers 117-1, ···, 117-n. Thereafter, in step S103, a fixing solution 115 for fixing the coloring solution 107 is applied. The above steps are repeated until the dental prosthesis 100 is completely constructed.

[0064] If the coloring solution 107 is inkjet printed onto the previously dried layers 117-1, ···, 117-n and then a wet slurry is applied again onto the previously dried and colored layers 117-1, ···, 117-n, the coloring solution 107 may redissolve and uncontrollably diffuse into the already constructed dental prosthesis 100. When inkjet printing the coloring solution 107 onto the dried layers 117-1, ···, 117-n, it is necessary to pay attention so that the penetration depth of the coloring solution 107 can be controlled. For example, if the penetration depth is greater than the layer thickness, coloring can be performed only after applying multiple layers of the slurry 109.

[0065] The application of the fixing solution 115 locally fixes the coloring solution 107, thus preventing uncontrollable diffusion or mixing by the precipitation of hydroxides. This can be achieved by applying a basic fixing solution 115, such as an ammonium chloride buffer solution, over a large area or selectively to change the pH value. The ammonium chloride buffer solution contains, for example, 987.8 g of water, 6.8 g of 25% ammonia, and 5.4 g of ammonium chloride.

[0066] Only one type of slurry 109 having a basic coloring and intermediate translucency can be used for additional material application to the dental prosthesis 100. In that case, selective coloring of the slurry 109 is performed by inkjet printing of the coloring solution, and the coloring solution is then fixed.

[0067] Since the slurry 109 and the coloring solution 107 have diverse hydrodynamic characteristics, various printing head technologies can be used. 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 etc. 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 printing head. In addition, the printing head must also be able to eject an aqueous medium.

[0068] In contrast, the coloring solution 107 has a lower viscosity (0.5 to 50 mPas). Since it is related to a high-concentration nitrate solution in that case, the printing head used needs to be resistant to nitrates. 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%. Furthermore, selective application of the coloring solution 107 can also be carried out by a multi-channel printing head 111-2.

[0069] In addition, the depth of penetration or diffusion of the coloring solution 107 can also be controlled by adjusting the viscosity. This is achieved by adding an appropriate thickening agent, such as polyvinylpyrrolidone (PVP) etc., which is stable in the pH range of the coloring solution, to the coloring solution 107.

[0070] Most of the amount is processed with respect to the slurry 109, while the coloring solution 107 is processed in a smaller amount. The coloring solution 107 and the slurry 109 can be stored in storage tanks 119-1 and 119-2 of different sizes.

[0071] Thereafter, the fully constructed dental prosthesis 100 is fired in a firing kiln. The slurry 109 and the coloring solution 107 can be adjusted to have consistent sintering characteristics. By adjusting the individual coloring solution 107, the sintering kinetics can be uniformly adjusted. By using or adding a sintering inhibitor, the sintering activator is "neutralized".

[0072] Regardless of whether the slurry 109 is pre-colored or the coloring is carried out only by selective application of the coloring solution 107 for each layer in the additional method layer-by-layer processing, a nitrate solution can be used as the coloring solution 107 for the selective coloring process.

[0073] 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 promoters, 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, opacity can be provided for the dentin core and translucency can be provided for the enamel.

[0074] 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.

[0075] 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.

[0076] 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

[0077] 100 Dental prosthesis 101 Dentin core 103 Enamel 105 Tooth 107 Coloring solution 109 Slurry 111 Print head 113 Dithering module 115 Fixing liquid 117 Layer 119 Storage tank 121 Coating device 123 Drying device

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; applying a fixative to fix the coloring solution. A method for producing a dental prosthesis by jet printing.

2. 2. The method of claim 1, wherein the fixer is sprayed onto the layer or layers.

3. 10. The method of claim 1, wherein the fixer fluid is jet printed onto the layer or layers using a print head.

4. 4. A method according to any one of claims 1 to 3, wherein the layer or layers are dried before or after the coloured solution is jet printed.

5. 5. A method according to any one of claims 1 to 4, wherein the layer or layers are dried before or after applying the fixer.

6. 6. The method according to claim 1, wherein the pH value of the fixer is greater than 7.

7. 7. The method according to claim 1, wherein the fixer is an ammoniacal ammonium chloride solution.

8. 8. The method according to claim 1, wherein the steps for producing a dental prosthesis are carried out iteratively.

9. 9. A method according to any one of claims 1 to 8, wherein the dental prosthesis is fired in a firing 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 colorant solution onto said layer or layers; a coating device for coating a fixing solution for fixing the coloring solution; A manufacturing device that produces dental prostheses by jet printing.

11. 11. The manufacturing apparatus according to claim 10, wherein the application device is constituted by a spray head for applying the fixing liquid in a planar manner.

12. 12. A manufacturing apparatus as claimed in claim 10 or 11, wherein the application device comprises a print head for selectively applying the fixer fluid.

13. 13. A manufacturing apparatus according to any one of claims 10 to 12, characterized in that it comprises a storage tank for the fixer solution.

14. 14. A manufacturing apparatus according to any one of claims 10 to 13, comprising a drying device for drying the applied material.

15. 15. The manufacturing apparatus according to any one of claims 10 to 14, wherein the drying device comprises a blower and / or an infrared radiator.

16. A manufacturing apparatus for manufacturing dental prostheses by jet printing; a coloring solution for printing in one or more layers; A fixing solution for fixing the coloring solution. Jetting printing system.

17. 17. The jetting printing system of claim 16, wherein the coloring solution and / or the fixer solution are stored in a tank.

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

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