Method, apparatus and system for producing dental prostheses by jet printing

Abstract

The invention relates to a method, an apparatus and a system for producing dental prostheses by jet printing. The invention provides a method for producing a dental restoration by jet printing, comprising the steps of: jet printing (S101) one or more layers of a dental restoration by means of a ceramic slurry; and jet printing (S102) a translucency enhancer and / or an opacity enhancer onto the one or more layers.

Description

Technical Field

[0001] The present invention relates to a method for producing dental restorations by jet printing and a production device for producing dental restorations by jet printing. Background Art

[0002] By means of jet printing of materials (also known as inkjet process), aqueous-based or solvent-based ZrO 2 slurries can be processed layer by layer into dental restorations. Jet printing enables the position-selective application of different slurries. These slurries can be pre-colored differently and can additionally have different translucencies and / or different mechanical properties.

[0003] In the case of ZrO 2 slurries, different yttrium-doped ceramic powders can be used for different strengths. Yttrium doping also affects the degree of translucency. Different yttrium-doped ceramic powders have different properties. For example, three different starting powders or slurries can be used to represent three translucency levels.

[0004] However, if different pre-colored slurries are used, and all of these slurries also have different translucencies and / or mechanical properties, then each of these slurries is assigned its own print head. For example, if a common CYMK color scheme is used to cover the entire color space, then 3×4 = 12 slurries must be set in 12 print heads. The production of these different slurries is also complex. Due to the large number of slurries, the supply and handling workload is correspondingly high. Summary of the Invention

[0005] The technical task of the present invention is to construct dental restorations with only a few base slurries (preferably a single one) and to selectively locally adjust the opacity or translucency during the production of dental restorations.

[0006] This task is solved by the subject matter according to the present invention.

[0007] According to a first aspect, this technical task is solved by a method for producing dental restorations by jet printing, the method comprising the steps of: jet printing one or more layers of the dental restoration by means of a ceramic slurry; and jet printing a translucency enhancer or an opacity enhancer onto the one or more layers. In jet printing, the respective materials are ejected drop by drop by a movable print head and applied in a position-selective manner (inkjet process).

[0008] The translucency enhancer increases the translucency of the dental restoration during the sintering process. In contrast, the opacity enhancer increases the opacity of the dental restoration during the sintering process. The reciprocal (mutual) property of translucency is opacity (non-transmittance of light).

[0009] This method allows for a reduction in the number of print heads in a production apparatus without restricting the freedom in terms of color, translucency, opacity, and hardness in dental restorations. This enables selective material application of the slurry, selective coloring, and selective adjustment of opacity, translucency, and hardness to be carried out in separate process steps. In this way, realistic dental restorations can be produced.

[0010] In a technically advantageous embodiment of this method, the translucency enhancer comprises oxides of elements such as yttrium, lanthanum, ytterbium, neodymium, and / or europium. This realizes, for example, the technical advantage of using a particularly suitable translucency enhancer.

[0011] In a further technically advantageous embodiment of this method, the opacity enhancer comprises oxides of elements such as aluminum and / or silicon. This realizes, for example, the technical advantage of using a particularly suitable opacity enhancer.

[0012] In a further technically advantageous embodiment of this method, one or more layers are dried before jet-printing the translucency enhancer or the opacity enhancer. This realizes, for example, the technical advantage of reducing the loss of the translucency enhancer or the opacity enhancer.

[0013] In a further technically advantageous embodiment of this method, the slurry has a yttrium content of less than 3 mol%. This realizes, for example, that the opaque slurry used can be made translucent with the help of a translucency enhancer. In this case, the opacity enhancer can be omitted.

[0014] In a further technically advantageous embodiment of this method, the slurry has a yttrium content between 3.5 mol% and 4.5 mol%. This realizes, for example, the technical advantage that the translucency and opacity of the slurry can be changed.

[0015] In a further technically advantageous embodiment of this method, the coloring solution is jet-printed onto one or more layers. This realizes, for example, the technical advantage that these layers can be colored in a position-selective manner.

[0016] In a further technically advantageous embodiment of this method, the coloring solution is doped with a translucency enhancer or an opacity enhancer. This realizes, for example, the technical advantage that translucency and opacity can be adjusted simultaneously during coloring.

[0017] In a further technically advantageous embodiment of the method, before the sintering process, a drying and / or debinding step is carried out on the produced dental restoration. This drying and / or debinding step can be carried out in a separate heat treatment or can be an upstream treatment step in the sintering process. Drying is usually carried out at a temperature between 25°C and 200°C, preferably between 30°C and 180°C, and particularly preferably between 40°C and 150°C. Additionally, the humidity can be adjusted between 10% and 90%, preferably between 15% and 85%, and particularly preferably between 20% and 80%. Debinding is usually carried out at a temperature between 50°C and 600°C, preferably between 100°C and 600°C, and particularly preferably between 200°C and 600°C. The heating rate is between 0.1 and 10 K / min, preferably between 0.2 and 10 K / min, and particularly preferably between 0.5 and 10 K / min.

[0018] In a further technically advantageous embodiment of the method, the dental restoration is sintered in a sintering furnace. This achieves the technical advantage that, for example, dental restorations with high strength can be produced.

[0019] According to a second aspect, this technical task is solved by a production device for producing dental restorations by inkjet printing, the production device comprising a first print head for inkjet printing one or more layers of a dental restoration by means of a ceramic slurry; and a second print head for inkjet printing a translucency enhancer or an opacity enhancer onto the one or more layers. The production device achieves the same technical advantages as the method according to the first aspect.

[0020] In a technically advantageous embodiment of the production device, the production device comprises a receiving container for the translucency enhancer and / or the opacity enhancer. The corresponding receiving container can be replaceable. This achieves the technical advantage that, for example, the translucency enhancer and / or the opacity enhancer are stored in the production device and can be easily replaced.

[0021] In a further technically advantageous embodiment of the production device, the production device comprises a drying device for drying the one or more layers. This achieves the technical advantage that, for example, the loss of the translucency enhancer and / or the opacity enhancer can be reduced.

[0022] In a further technically advantageous embodiment of the production device, the drying device comprises a blower and / or an infrared emitter. This achieves the technical advantage that, for example, the layers can be dried quickly and without cracks.

[0023] In a further technically advantageous embodiment of the production device, the production device comprises a dithering module for calculating intermediate translucency values. This achieves the technical advantage that, for example, dental restorations can be produced with finely adjusted translucency values.

[0024] In a further technically advantageous embodiment of the production apparatus, the dithering module is adapted to use different two-dimensional dithering patterns in successive layers of the dental restoration. This has the technical advantage of, for example, preventing the formation of streaks or moiré patterns in the dental restoration.

[0025] According to a third aspect, this technical task is solved by an inkjet printing system comprising a production apparatus for producing a dental restoration by inkjet printing, a ceramic slurry for printing one or more layers, and a translucency enhancer and / or an opacity enhancer for inkjet printing onto one or more layers. The inkjet printing system achieves the same technical advantages as the method according to the first aspect.

[0026] In a technically advantageous embodiment of the inkjet printing system, the ceramic slurry, the translucency enhancer and / or the opacity enhancer are stored in a container. This has the technical advantage of, for example, enabling the reliable storage of the ceramic slurry, the translucency enhancer and / or the opacity enhancer.

[0027] In a further technically advantageous embodiment of the inkjet printing system, the container is replaceable. This has the technical advantage of, for example, enabling the easy exchange of the solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Exemplary embodiments of the invention are shown in the drawings and described in more detail below, wherein:

[0029] Figure 1 A diagram showing different regions of an incisor is shown;

[0030] Figure 2 A schematic diagram of a dental restoration is shown;

[0031] Figure 3 A schematic diagram of a production apparatus for producing a dental restoration is shown;

[0032] Figure 4 A schematic diagram showing an increase in translucency is shown;

[0033] Figure 5 A schematic diagram showing an increase in translucency or an increase in opacity; and

[0034] Figure 6 A block diagram of a method for producing a dental restoration is shown. DETAILED DESCRIPTION

[0035] Figure 1Representations of different areas of a tooth 105 are shown. The tooth 105 comprises an inner dentin core 101 and an outer enamel 103. The opaque, i.e. non-transparent, dentin core 101 is responsible for the basic coloring of the tooth 105. The dentin core 101 shines through the enamel 103 at the edge of the tooth. On the other hand, the enamel 103 is usually translucent, i.e. translucent. Translucency is the partial light transmission of an object. This structure of the tooth 105 is also used in artificial dental restorations in order to make the dental restorations look as realistic as possible. For this purpose, materials with different optical properties are used in the production of dental restorations.

[0036] Figure 2 A schematic diagram of a dental restoration 100 is shown. The dental restoration 100 is used as a dental prosthesis and is formed, for example, by a dental bridge, a crown, a complete or partial prosthesis. The dental restoration 100 is constructed, for example, with the aid of different ceramic slurries 109, which include 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 For this purpose, during the spatial production of the dental restoration 100 by means of a jet printing process, these slurries 109 are applied selectively to the respective areas.

[0037] The dental restoration 100 is built up of successive layers printed on top of each other. The ceramic powders of the slurries 109 may already be provided with a predetermined translucency. Mixing these slurries 109 produces a target translucency of the dental restoration 100 in the corresponding spatial regions.

[0038] After selective material application of a layer of paste 109 using a jet printing process, the layer is dried without cracks by evaporation of the solvent or water as a binder. What remains is a layer having 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 restoration 100 is constructed spatially layer by layer.

[0039] Figure 3The figure shows a schematic view of a production device 200 for producing a dental prosthesis 100 by inkjet printing of an aqueous or solvent-based slurry 109. To additionally produce ceramic, dental multi-material, and multi-color prostheses 100 by inkjet printing, the base slurry 109 is processed.

[0040] The production device 200 includes a plurality of holding containers 119-1 in which base slurries 109 with different optical properties are arranged. In addition, the production device 200 includes at least one holding container 119-2 in which a translucency enhancer or an opacity enhancer is stored. Additionally, the production device 200 includes a holding container 119-3 for holding a coloring solution 115 and a holding container 119-4 for holding a fixing solution 116. A production device for producing a dental prosthesis by inkjet printing; a ceramic slurry; a translucency enhancer and / or an opacity enhancer for inkjet printing on one or more layers together form an inkjet printing system.

[0041] The ceramic slurries 109 are each applied drop by drop in a plurality of layers 117-1, 117-2, ……, 117-n by means of a designated print head 111-1 so as to spatially build the dental prosthesis 100 layer by layer. The print head for applying the slurry and the build platform 106 can be moved relative to each other along three spatial axes (XYZ) such that the slurry 109 can be printed at any position. The slurry 109 having a droplet volume typically of 10 to 100 pL is used for selective material application. For example, an electro-controlled piezoelectric element is used to eject the droplets.

[0042] Using a solvent-based or aqueous ceramic slurry and evaporating the solvent or water by drying after applying the coating eliminates the time-consuming debinding process required if a polymer is used as a binder.

[0043] To apply the translucency enhancer or opacity enhancer 107, an additional print head 111-2 is used, by means of which the translucency enhancer or opacity enhancer 107 can be inkjet printed onto one or more layers 117-1, ……, 117-n. The print head 111-2 can also be moved relative to the build platform 106 along three spatial axes (XYZ) such that the translucency enhancer or opacity enhancer 107 can be printed at any position.

[0044] An additional print head 111-3 is used to apply the coloring solution 115, by means of which the coloring solution 115 can be inkjet printed onto one or more layers 117-1, ……, 117-n. The print head 111-3 can also be moved relative to the build platform 106 along three spatial axes (XYZ) such that the coloring solution can be printed at any position.

[0045] To apply a fixing solution 116 for fixing the coloring solution 115 or the translucency enhancer or opacity enhancer 107, an additional printhead 111-4 is used, by means of which the fixing solution 116 can be jet-printed onto one or more layers 117-1, …, 117-n. The printhead 111-4 can also be moved relative to the build platform 106 on three spatial axes (XYZ) so that the coloring solution can be printed at any position.

[0046] The printheads 111-1, 111-2, 111-3, and 111-4 can be controlled independently or integrated in a common print module.

[0047] Of course, the printhead 111 can also be fixed, and the build platform 106 with the printed dental prosthesis 100 and the most recently printed layer 117 is moved relative to the printhead 111 in three directions (XYZ) so that the slurry 109, the translucency enhancer or opacity enhancer 107, the coloring solution 115, or the fixing solution 116 can be printed at any position.

[0048] A drying device 123 is provided for drying the aqueous materials, by means of which the layers 117-1, …, 117-n and the translucency enhancer or opacity enhancer 107 can be dried without cracks. The drying device 123 is formed, for example, by a blower and / or an infrared emitter.

[0049] The production device 200 provides a reduced number of pre-colored and yttrium-doped neutral base slurries 109 to minimize the number of printheads 111-1 and 111-2 and still achieve the aesthetic and functional results of the dental prosthesis 100. A color reduction system is used, which spans a limited dental color space (dental color gamut). Then, these pre-colored slurries 109 are created by mixing colors, three-dimensional halftoning, or dithering at various ratios in a specific dental color space (color gamut) that covers common tooth colors but not all colors.

[0050] During production, the translucency enhancer or opacity enhancer 107 is selectively applied to the layers 117-1, …, 117-n via a 3D dithering algorithm, which is executed by a dithering module. For this purpose, the dithering module includes a processor for executing the 3D dithering algorithm and a digital data memory for storing the calculated mixing ratios 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 system having a central processing unit (CPU), multiple data processing units (MPU), a dedicated circuit for implementing functions, or other systems. The data memory can include a hard disk, a flash card, a random access memory (RAM), or a read-only memory (ROM).

[0051] During jittering, using an inkjet printing process, a translucency enhancer or an opacity enhancer 107 is selectively applied onto a printing plane at a certain ratio and a two-dimensional printing pattern is formed. A 3D jittering algorithm also calculates different two-dimensional jittering patterns to be applied in a plurality of layers 117-1, ……, 117-n stacked on top of each other. This can prevent optical artifacts such as streaks or moiré patterns from appearing on vertical surfaces. These pre-colored slurries 109 are created with various ratios of color mixing, three-dimensional halftoning or jittering in a specific dental color space (color gamut) that covers common tooth colors but not all general colors.

[0052] When using a highly viscous slurry 109 with a viscosity greater than 100 mPas and highly filled, special requirements are imposed on the print head 111-1 and its fluid system. The print head 111-1 is compatible with the binder and / or the carrier material of the slurry 109 used, such as being compatible with water in the case of an aqueous slurry 109, to avoid corrosion.

[0053] After selectively applying the slurry 109 to the layers 117-1, ……, 117-n by means of an inkjet printing process, the layers 117-1, ……, 117-n are dried by evaporating the solvent or water acting as the binder without cracking. The ceramic powder of the slurry 109 may have been colored to a certain color, such as a base color or a tooth color. What remains is a porous white body layer with a layer thickness of 1 μm to 50 μm and a density of at least 3.0 g / cm 3 and is repeated until the entire dental restoration 100 is spatially constructed layer by layer.

[0054] Figure 4 A schematic diagram showing an increase in translucency is shown. The dental restoration 100 is constructed layer by layer from a slurry 109 with low translucency and high strength. Therefore, the opacity of the slurry 109 is high. For example, a slurry with yttrium-3Y-TZP with a yttrium content of 3 mol% is used for this purpose. Starting from this slurry 109, the translucency is selectively increased by positioning an inkjet-printed translucency enhancer. Through the selective printing of the positioning of the translucency enhancer, the translucency can be adjusted within the range of 90% to 50% of the CR value.

[0055] Figure 5 A schematic diagram showing an increase in translucency or opacity is shown. The dental restoration 100 is constructed layer by layer from a slurry 109 with medium translucency or opacity. For example, a slurry with yttrium-4Y-TZP with a yttrium content of 4 mol% is used for this purpose.

[0056] Starting from this slurry 109, the translucency is selectively increased in a targeted manner by jet-printing a translucency enhancer 107, or the opacity is selectively increased in a targeted manner by jet-printing an opacity enhancer 107. In this way, the characteristics of the translucency or opacity of the slurry 109 can be adjusted in a targeted manner.

[0057] In addition to locally and selectively adjusting the translucency, opacity, and hardness during the layer construction of the dental restoration 100, a coloring solution 115 can be used to selectively color locally. This is advantageous if only a single base slurry with a medium translucency of the base color is used. The coloring solution 115 can already be doped with appropriate rare earths in order to further reduce the number of required printheads 111 without restricting the freedom of color, translucency, opacity, and hardness.

[0058] Figure 6 A block diagram of a method for producing a dental restoration is shown. In step S101, one or more layers 117-1, ……, 117-n of the dental restoration 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. Here, a single slurry 109 with a base color and a medium translucency (for example, a yttrium content of 4 mol% (4Y-TZP)) can be used for the additive material of the dental restoration 100. Selective coloring is achieved by jet-printing the coloring solution 115. A slurry with discrete particles in the nano range (5 nm - 100 nm) or sub-micron range (100 nm - 1 μm) or an ionic solution with a high concentration can be used.

[0059] Selective adjustment of opacity, translucency, and hardness is achieved by selectively applying ionic solutions containing different components of yttrium, lanthanum, ytterbium, and other rare earths. For example, Y 3+ 、La 3+ 、Yb 3+ 、Nd 3+ and Eu 3+ are used as translucency enhancers, and Al 3+ 、Si are used as opacity enhancers.

[0060] Generally, the opaque dentin core determines the color of the dental restoration 100, and the translucent edge determines the vibrancy of the dental restoration. For example, through appropriately doped translucency enhancers, the yttrium content can be increased from 3Y to 5Y. This allows different opacity values to be achieved in a position-selective manner in the dental restoration 100, such as an opaque space area of the dentin core and a translucent space area of the edge.

[0061] A highly aesthetic and functional dental restoration 100 can be produced by mixing two pre-colored slurries 109 with light and dark tooth colors of medium translucency and opacity and selectively adding a translucency enhancer or an opacity enhancer. For example, two high-strength and light-blocking slurries can be mixed for the dentin core and a translucency enhancer can be added in the corresponding area to obtain a less robust, translucent incisal edge. In this case, only 4 print heads are required:

[0062] 1 Support material

[0063] 2 3Y-TZP slurry - light color (light-blocking, high strength)

[0064] 3 3Y-TZP slurry - dark color (light-blocking, high strength)

[0065] 4 Yttrium solution (for local control of translucency and strength)

[0066] Alternatively, a dental restoration can be constructed with a medium-translucent slurry 109, where a translucency enhancer or an opacity enhancer (light-blocking liquid) is selectively added.

[0067] The selective addition of the translucency enhancer or the opacity enhancer can occur on the wet spray printed layers 117-1,..., 117-n (wet-on-wet) or on the dry spray printed layers 117-1,..., 117-n (wet-on-dry). Chemical transformation occurs during the subsequent sintering process of the selectively doped green body. This produces the desired optical properties.

[0068] All features explained and shown in connection with the various embodiments of the present invention can be provided in different combinations in the subject matter of the present invention in order to achieve their advantageous effects simultaneously.

[0069] All method steps can be implemented by devices suitable for performing the respective method steps. All functions performed by the features of the subject matter can be method steps of a method.

[0070] The scope of protection of the present invention is given by the claims and is not limited to the features explained in the specification or shown in the drawings.

[0071] List of reference numerals

[0072] 100 Dental restoration

[0073] 101 Dentin core

[0074] 102 Intermediate area

[0075] 103 Enamel

[0076] 105 Tooth

[0077] 106 Building platform

[0078] 107 Translucency enhancer / Opacity enhancer

[0079] 109 Slurry

[0080] 111, 111-1, 111-2, 111-3, 111-4 Print heads

[0081] 115 Coloring solution

[0082] 116 Fixing solution

[0083] 117-1, 117-2, 117-n Layers

[0084] 119-1, 119-2, 119-3, 119-4 Containing containers

[0085] 123 Drying equipment

[0086] 200 Production device.

Claims

1. A method for producing a dental restoration by jet printing, comprising the following steps: - printing one or more layers of the dental restoration by means of ceramic slurry jetting; - jet printing a translucency enhancing agent or an opacity enhancing agent onto the one or more layers.

2. The method according to claim 1, wherein: The translucency enhancer includes oxides of yttrium, lanthanum, ytterbium, neodymium and / or europium.

3. A method according to any one of the preceding claims, wherein: The opacity enhancer includes aluminum and / or silicon.

4. A method according to any one of the preceding claims, wherein: The one or more layers are dried prior to jet printing the translucency enhancing agent or opacity enhancing agent.

5. A method according to any one of the preceding claims, wherein: The slurry has a yttrium content of less than 3 mol%.

6. A method according to any one of the preceding claims, wherein: The slurry has a yttrium content between 3.5 mol% and 4.5 mol%.

7. A method according to any one of the preceding claims, wherein: A coloring solution is jet printed onto the one or more layers.

8. A method according to any one of the preceding claims, wherein: The tinted solution is doped with a translucency enhancer or an opacity enhancer.

9. A method according to any one of the preceding claims, wherein: Prior to the sintering process, the produced dental restoration is subjected to a drying and / or degreasing step.

10. A production device for producing a dental restoration by jet printing, comprising: - a first print head for jet printing one or more layers of the dental restoration by means of a ceramic slurry; as well as - a second print head for jet printing a translucency enhancing agent or an opacity enhancing agent onto the one or more layers.

11. The production device according to claim 10, wherein: The production device includes a holding container for the translucency enhancing agent and / or opacity enhancing agent.

12. The production device according to claim 10 or 11, wherein: The production apparatus comprises a drying device for drying the one or more layers.

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

14. The production device according to any one of claims 10 to 13, wherein: The production device comprises a dithering module for calculating intermediate translucency values.

15. The production device according to any one of claims 10 to 14, wherein: The dithering module is adapted to use different two-dimensional dithering patterns in consecutive layers of the dental restoration.

16. Inkjet printing system, including: - a production device for producing dental restorations by inkjet printing; - Ceramic slurry for printing one or more layers; as well as - Translucency enhancers and / or opacity enhancers for jet printing onto one or more layers.

17. The jet printing system according to claim 16, wherein: The ceramic slurry, the translucency enhancer and / or the opacity enhancer are stored in a container.

18. The jet printing system according to claim 17, wherein: The container is replaceable.

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