Selective adjustment of hardness and translucency in multi-color ceramic inkjet 3D printing

Abstract

To obtain a method and an apparatus for producing a dental restoration by jet-printing, which can build up a dental restoration using only a very small number of base slurries, at best a single one, and can selectively adjust and match opacity or translucency locally when producing the dental restoration.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; and a step (S102) of jet-printing a translucency enhancer or an opacity enhancer onto the one layer or the plurality of layers.SELECTED DRAWING: Figure 6

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] An aqueous or solvent-based ZrO 2 slurry can be processed into a dental prosthesis layer by layer using inkjet printing (also known as the inkjet method) of materials. According to inkjet printing, it is possible to locally select and apply different slurries. Those slurries can be differently colored and can additionally have different translucencies and / or different mechanical properties.

[0003] ZrO 2 In the case of a slurry, ceramic powders doped with yttrium differently for different strengths can be applied. In that case, yttrium doping can also be a factor regarding the degree of translucency. Ceramic powders doped with yttrium differently have different properties. For example, three different initial powders or slurries can be used to form a three-stage translucency.

[0004] On the other hand, when using slurries that are differently pre-colored and all have different translucencies and / or mechanical properties respectively, a dedicated print head is assigned to each of those slurries. For example, when using a common CYMK color scheme to cover the entire color space, 3×4 = 12 slurries are included in 12 print heads. Manufacturing those different slurries is also complicated. Such a large number of slurries also makes the procurement and processing costs quite high.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of the present invention is to construct a dental prosthesis using a very small number, and in the best case only one type, of base slurries, and to locally select and adapt the opacity or translucency during the production of the dental prosthesis.

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: jet printing one or more layers of a dental prosthesis using a ceramic slurry; and jet printing a translucency enhancer or an opacity enhancer on the one or more layers. During inkjet printing, the corresponding material is locally selected by a movable print head and ejected and applied in droplets (inkjet method).

[0008] The translucency enhancer increases the translucency of the dental prosthesis during the sintering process. In contrast, the opacity enhancer increases the opacity of the dental prosthesis during the sintering process. The opposite (relative) property to translucency is opacity (non-transparency).

[0009] According to this method, the number of print heads of the manufacturing apparatus can be reduced without restricting the degrees of freedom of color, translucency, opacity, and hardness in the dental prosthesis. Therefore, selective material application of the slurry, selective coloring, and selective adjustment of opacity, translucency, and hardness can be performed within mutually separated process steps. In that way, a dental prosthesis faithful to nature can be manufactured.

[0010] According to a technically preferred embodiment of this method, the translucency enhancer contains oxides of yttrium, lanthanum, ytterbium, neodymium, and / or europium. Thereby, for example, the technical advantage that a very suitable translucency enhancer is used is achieved.

[0011] According to another technically preferred embodiment of this method, the opacity enhancer contains oxides of aluminum and / or silicon. Thereby, for example, the technical advantage that a very suitable opacity enhancer is used is achieved.

[0012] According to another technically preferred embodiment of this method, one or more layers are dried before the translucency enhancer or the opacity enhancer is inkjet printed. Thereby, for example, the technical advantage that the outflow of the translucency enhancer or the opacity enhancer can be reduced is achieved.

[0013] According to another technically preferred embodiment of this method, the slurry has a yttrium content of less than 3 mol%. Thereby, for example, the technical advantage that an opaque slurry that can be made translucent by the translucency enhancer is used is achieved. In that case, the opacity enhancer can be omitted.

[0014] According to another technically preferred embodiment of this method, the slurry has a yttrium content of 3.5 to 4.5 mol%. Thereby, for example, the technical advantage that both the translucency and the opacity of the slurry can be made variable is achieved.

[0015] According to another technically preferred embodiment of this method, a coloring solution is inkjet printed onto one or more layers. Thereby, for example, the technical advantage that the layers can be colored by local selection is achieved.

[0016] According to another technically preferred embodiment of this method, the coloring solution is doped with a translucency enhancer or an opacity enhancer. Thereby, for example, a technical advantage that translucency and opacity can be adjusted simultaneously with coloring is achieved.

[0017] 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 carried out 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 carried out 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.

[0018] According to another technically preferred embodiment of this method, the dental prosthesis is sintered in a sintering furnace. Thereby, for example, a technical advantage that a dental prosthesis having high strength can be manufactured is achieved.

[0019] According to a second aspect, the above-described technical problem is solved by a manufacturing apparatus for manufacturing a dental prosthesis by inkjet printing, the manufacturing apparatus having a first print head for inkjet printing one or more layers of the dental prosthesis using a ceramic slurry, and a second print head for inkjet printing a translucency enhancer or an opacity enhancer on the one or more layers. By this manufacturing apparatus, the same technical advantages as those of the method according to the first aspect described above are achieved.

[0020] According to another technically preferred embodiment of this manufacturing apparatus, the manufacturing apparatus includes a storage tank for a translucency enhancer and / or an opacity enhancer. The storage tank can be made replaceable. Thereby, for example, the technical advantage that the translucency enhancer and / or the opacity enhancer can be stored in the manufacturing apparatus and used conveniently is achieved.

[0021] According to another technically preferred embodiment of this manufacturing apparatus, the manufacturing apparatus includes a drying device for drying one or more layers. Thereby, for example, the technical advantage that the outflow of the translucency enhancer and / or the opacity enhancer can be reduced is achieved.

[0022] 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, the technical advantage that the layer can be dried rapidly and without cracking is achieved.

[0023] According to another technically preferred embodiment of this manufacturing apparatus, the manufacturing apparatus includes a dithering module for calculating intermediate translucency values. Thereby, for example, the technical advantage that a dental prosthesis having a precisely adjusted translucency value can be manufactured is achieved.

[0024] 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, the technical advantage that the occurrence of stripes or wavy patterns in the dental prosthesis is prevented is achieved.

[0025] According to a third aspect, a manufacturing apparatus for manufacturing a dental prosthesis by inkjet printing; a ceramic slurry for printing one or more layers; and a semi-transparency enhancer and / or an opacity enhancer for inkjet printing on the one or more layers, the above-described technical problem is solved by an inkjet printing system. By this inkjet printing system, the same technical advantages as those of the method according to the first aspect described above are achieved.

[0026] According to a technically preferred embodiment of this inkjet printing system, the ceramic slurry, the semi-transparency enhancer and / or the opacity enhancer are accommodated in a storage tank. Thereby, for example, the technical advantage of being able to safely accommodate the ceramic slurry, the semi-transparency enhancer and / or the opacity enhancer is achieved.

[0027] According to another technically preferred embodiment of this inkjet printing system, the storage tank is replaceable. Thereby, for example, the technical advantage of being able to easily change the solution is achieved.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0029] Next, embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0030] FIG. 1 shows different parts of a tooth 105. The tooth 105 has an inner dentin core 101 and an outer enamel 103. A turbid color, i.e., an opaque dentin core 101, is required for the basic coloring of the tooth 105. The dentin core 101 is visible through the enamel 103 at the incisal edge. On the other hand, the enamel 103 is often visible, 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.

[0031] 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 composed, for example, using different ceramic slurries 109, and Fe 2 O 3 , Cr 2 O 3 , Mn 2 O 3 , Tb 2 O 3 , Pr 2 O 3 , Er 2 O 3 , CeO 2 , NiO, TiO 2 , and Co 3 O 4 etc. are included. Therefore, when the dental prosthesis 100 is three-dimensionally manufactured using an inkjet printing method, the slurry 109 is applied selectively to the corresponding places.

[0032] 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.

[0033] 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, which has 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.

[0034] FIG. 3 shows a schematic view 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 ceramic multi-material and multi-color dental prosthesis 100 in an additive manner by inkjet printing.

[0035] The manufacturing apparatus 200 includes a plurality of storage tanks 119-1 that contain base slurries 109 having different optical properties. In addition, the manufacturing apparatus 200 includes at least one storage tank 119-2 that contains a translucent enhancer or an opaque enhancer. Additionally, the manufacturing apparatus 200 includes a storage tank 119-3 that contains a coloring solution 115 and a storage tank 119-4 that contains a fixing solution 116. A manufacturing apparatus for manufacturing a dental prosthesis by inkjet printing; a ceramic slurry; and a translucent enhancer and / or an opaque enhancer for inkjet printing on one or more layers, together constitute an inkjet printing system.

[0036] To build the dental prosthesis 100 layer by layer in three dimensions, a ceramic slurry 109 is applied in droplets as a plurality of layers 117-1, ···, 117-n using a print head 111-1 to which each ceramic slurry is assigned. The print head and the build platform 106 are relatively movable in three spatial directions (XYZ) for applying the slurry, and thus the slurry 109 can be printed at any position. The slurry 109 is typically used with a droplet volume of 10 to 100 picoliters for selective material application. For ejecting the droplets, for example, an electrically controlled piezoelectric element is used.

[0037] When using a solvent-based or aqueous ceramic slurry and drying after layer coating to vaporize the solvent or water, the time-consuming debinding process required when using a polymer as a binder is omitted.

[0038] Another print head 111-2 is used to apply the translucency enhancer or opacity enhancer 107, and the print head can jet-print the translucency enhancer or opacity enhancer 107 onto one or more layers 117-1, ···, 117-n. The print head 111-2 is also operable relative to the build platform 106 in three spatial directions (XYZ), and thus the translucency enhancer or opacity enhancer 107 can be printed at any position.

[0039] Another print head 111-3 is used to apply the coloring solution 115, and the print head can jet-print the coloring solution 115 onto one or more layers 117-1, ···, 117-n. The print head 111-3 is also operable relative to the build platform 106 in three spatial directions (XYZ), and thus the coloring solution can be printed at any position.

[0040] Another print head 111-4 is used to apply the fixing solution 116 that functions to fix the coloring solution 115 or the translucency enhancer or opacity enhancer 107, and the print head can jet-print the fixing solution 116 onto one or more layers 117-1, ···, 117-n. The print head 111-4 is also operable relative to the build platform 106 in three spatial directions (XYZ), and thus the fixing solution can be printed at any position.

[0041] 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.

[0042] Of course, the printing head 111 can be made stationary and the construction platform 106 can be operated relative to the printing head 111 in three spatial directions (XYZ) together with the printed dental prosthesis 100 and the last printed layer 117, thereby enabling the printing of the slurry 109, the translucency enhancer or the opacity enhancer 107, the coloring solution 115, or the fixing solution 116 at any position.

[0043] A drying device 123 is provided to dry the aqueous material, thereby enabling the drying of the layers 117-1, ···, 117-n and the translucency enhancer or the opacity enhancer 107 without cracking. The drying device 123 is constituted by, for example, a blower and / or an infrared irradiation device.

[0044] 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 printing heads 111-1 and 111-2 and still achieve the aesthetics and functionality of the dental prosthesis 100. 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 are created within a specific dental color space (color gamut) that covers all common tooth colors but not all colors.

[0045] During manufacturing, the translucency enhancer or the opacity enhancer 107 is selectively applied onto the layers 117-1, ···, 117-n according to a 3D dithering algorithm executed by the dithering module 113. Therefore, the dithering module 113 comprises a processor for executing the 3D dithering algorithm and a digital memory for storing the calculated mixing ratio and the said dithering algorithm. The processor comprises any hardware system, component, or mechanism for processing data, signals, or other information. The processor can comprise a central data processing unit (CPU) and a system with multiple data processing units (MPU), a dedicated electric circuit for executing functions, or other systems. The data memory can comprise a hard disk, a flash memory card, a random access memory (RAM), or a read-only memory (ROM).

[0046] During dithering, the translucency enhancer or the opacity enhancer 107 is 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 such 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. The color composition, three-dimensional halftoning, or dithering of the slurries 109 pre-colored in different ratios is generated within the range of a specific dental color space (color gamut), which, although covering general tooth colors, does not cover all colors in general.

[0047] When using a high-viscosity slurry 109 with a 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 corrosion, the print head 111-1 is made compatible with the binder and / or the carrier material of the slurry 109 used, for example, water in the case of an aqueous slurry 109.

[0048] 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, can be colored 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 3.0 g / cm 3 and having a density of at least 3.0 g / cm³. The process is repeated until the entire dental prosthesis 100 is three-dimensionally constructed layer by layer.

[0049] FIG. 4 shows an overview of the increase in translucency. The dental prosthesis 100 is constructed layer by layer from the slurry 109 having low translucency and high strength. Thereby, the opacity of the slurry 109 becomes high. Therefore, for example, a slurry of yttrium 3Y-TZP having a yttrium content of 3 mol% is used. Starting from the slurry 109, the translucency is locally enhanced by inkjet printing of a translucency enhancer. By locally selectively printing the translucency enhancer, the translucency can be adjusted in the range of CR values from 90% to 50%.

[0050] FIG. 5 shows an overview of the increase in translucency or the increase in opacity. The dental prosthesis 100 is constructed layer by layer from the slurry 109 having medium translucency or opacity. Therefore, for example, a slurry of yttrium 4Y-TZP having a yttrium content of 4 mol% is used.

[0051] Starting from the slurry 109, the translucency is locally enhanced by inkjet printing of the translucency enhancer 107, or the opacity is enhanced by inkjet printing of the opacity enhancer 107. By this method, the translucency or opacity property of the slurry 109 can be adjusted according to the purpose.

[0052] In addition to the locally selected adjustment of translucency, opacity, and hardness during the layer construction of the dental prosthesis 100, the dental prosthesis can also be locally and selectively colored using a coloring solution 115. This method is advantageous when only a single base slurry with medium translucency and a basic color is used. In order to further reduce the number of required print heads 111 without restricting the degrees of freedom of color, translucency, opacity, and hardness, any of the coloring solutions 115 can be pre-doped with an appropriate rare earth.

[0053] FIG. 6 shows a block diagram of a method for manufacturing a dental prosthesis. In step S101, one or more layers 117-1, ···, 117-n of the dental prosthesis 100 are jet-printed using a ceramic slurry 109. In step S102, a translucency enhancer or an opacity enhancer 107 is jet-printed onto one or more layers 117-1, ···, 117-n. In that case, a single slurry 109 having a basic color and medium translucency, for example, one having a yttrium content of 4 mol% (4Y-TZP), can be used for the additional material coating of the dental prosthesis 100. In that case, selective coloring is performed by jet-printing the coloring solution 115. A slurry having dispersed particles in the nano-region (5 nm to 100 nm) or the sub-micron region (100 nm to 1 μm), or a highly concentrated ionic solution can be used.

[0054] The selective adjustment of opacity, translucency, and hardness is performed by selectively applying an ionic solution having variable components of yttrium, lanthanum, ytterbium, and other rare earths. For example, Y 3+ , La 3+ , Yb 3+ , Nd 3+ and Eu 3+ can be used as a translucency enhancer, and Al 3+ , Si can be used as an opacity enhancer.

[0055] Generally, an opaque dentin core is required for color, and a translucent incisal edge is required for the lifelike feeling of the dental prosthesis 100. By appropriately doping a translucency enhancer, for example, the yttrium content can be increased from 3Y to 5Y. Thereby, different opacity values can be achieved locally within the dental prosthesis 100, for example, an opaque spatial region for the dentin core and a translucent spatial region for the incisal edge can be provided.

[0056] Two types of slurries 109 with medium translucency and opacity and pre-colored in light and dark tooth colors are mixed, and by selectively adding a translucency enhancer or an opacity enhancer, a dental prosthesis 100 with high aesthetic and functional properties can be manufactured. For example, two types of high-strength and opaque slurries can be mixed for the dentin core, and a translucency enhancer can be added to an appropriate area for the less strong and translucent incisal edge. In that case, only the following four printing heads are required: 1 Carrier material 2 3Y-TZP slurry - light color (opaque, high strength) 3 3Y-TZP slurry - dark color (opaque, high strength) 4 Yttrium solution (for local adjustment of translucency and strength)

[0057] Alternatively, a dental prosthesis can be constructed using a slurry 109 with medium translucency, and a translucency enhancer or an opacity enhancer (opacifying solution) can be selectively added thereto.

[0058] The selective addition of a translucency enhancer or an opacity enhancer can be carried out on the wet jet-printed layers 117-1, ···, 117-n (wet ones to wet ones), or on the dry jet-printed layers 117-1, ···, 117-n (wet ones to dry ones). Chemical conversion occurs during the subsequent sintering process of the selectively doped green body. Thereby, the required optical properties are achieved.

[0059] All features described and illustrated in connection with individual embodiments of the present invention can be the subject of the present invention in various combinations, thereby simultaneously achieving effective advantages.

[0060] All method steps can be executed using an apparatus suitable for executing each method step. All functions executed by the features of interest can be method steps in this method.

[0061] 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

[0062] 100 Dental prosthesis 101 Dentin core 103 Enamel 105 Tooth 106 Construction platform 107 Translucency enhancer / Opacity enhancer 109 Slurry 111 Print head 113 Dithering module 115 Coloring solution 116 Fixing solution 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 translucency enhancing or opacity enhancing agent onto said layer or layers. A method for producing a dental prosthesis by jet printing.

2. 10. The method of claim 1, wherein the translucency enhancing agent comprises oxides of yttrium, lanthanum, ytterbium, neodymium, and / or europium.

3. 3. The method of claim 1 or 2, wherein the opacity enhancing agent comprises aluminum and / or silicon.

4. A method according to any one of claims 1 to 3, wherein the layer or layers are dried before the translucency enhancing agent or opacity enhancing agent is jet printed.

5. 5. The method of claim 1, wherein the slurry has a yttrium content of less than 3 mol %.

6. 6. A method according to any one of claims 1 to 5, wherein the slurry has a yttrium content of 3.5 to 4.5 mol %.

7. 7. A method according to any one of claims 1 to 6, wherein the coloured solution is jet printed onto the layer or layers.

8. 8. A method according to any one of claims 1 to 7, characterized in that the coloured solution is doped with a translucency enhancing agent or an opacity enhancing agent.

9. 9. A method according to any one of claims 1 to 8, wherein the produced dental prosthesis is subjected to a drying and / or debinding step prior to the sintering process.

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 translucency enhancing agent or an opacity enhancing agent onto said layer or layers. A manufacturing device that produces dental prostheses by jet printing.

11. 11. The manufacturing apparatus of claim 10, wherein the manufacturing apparatus comprises a storage tank for a translucency enhancer and / or an opacity enhancer.

12. 12. The apparatus according to claim 10 or 11, comprising a drying device for drying the layer or layers.

13. 13. The manufacturing apparatus according to any one of claims 10 to 12, wherein the drying device comprises a blower and / or an infrared radiator.

14. 14. An apparatus according to any one of claims 10 to 13, wherein the apparatus comprises a dithering module for calculating intermediate values ​​of translucency.

15. 15. An apparatus according to any one of claims 10 to 14, 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; A ceramic slurry for printing one or more layers; a translucency enhancer and / or an opacity enhancer for jet printing onto said layer or layers. Jetting printing system.

17. The jetting printing system of claim 16 , wherein the ceramic slurry, the translucency enhancer and / or the opacity enhancer are contained in a storage tank.

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

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