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 present invention provides a method for producing a dental restoration by jet printing, comprising the steps of: jet printing (S101) a dentin core of a dental restoration using a plurality of opaque ceramic slurries having different colors from each other; and jet printing (S102) a dental enamel of the dental restoration using the translucent ceramic slurry.

Description

Technical Field

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

[0002] Today, different pre-colored, solvent-based ceramic slurries (e.g., made of zirconia) are selectively applied drop by drop using a jet process (inkjet process) and dried into multiple layers. However, processing highly filled ceramic slurries places high demands on the printheads used in terms of particle size, filling level, viscosity, wear, and corrosion. Jet printing (jetting) of aqueous ceramic slurries is an alternative to solvent-based slurries. Summary of the Invention

[0003] The technical task of the present invention is to produce ceramic dental restorations with true color and natural appearance by means of a three-dimensional printing process.

[0004] This task is solved by the subject matter according to the present invention.

[0005] 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 a dentin core of a dental restoration using a plurality of opaque ceramic slurries having different colors from each other; and jet printing tooth enamel of the dental restoration using a translucent ceramic slurry. An aqueous-based or solvent-based slurry can be used as the ceramic slurry. This method provides a limited number of pre-colored slurries to reduce the number of printheads required and still achieve a highly aesthetic and functional result for the dental restoration.

[0006] An opaque slurry is a slurry that is opaque and does not transmit light after a sintering process. In contrast, a translucent slurry is a slurry that transmits some light but does not allow a clear image or shape to be recognized after a sintering process. The reciprocal (mutual) property of translucency is opacity (opacity to light). If the sintered slurry (i.e., the final ceramic) has a high translucency, its opacity in the dental restoration is low, and vice versa. Before the sintering process, the optical properties of the various slurries are usually different. Translucency or opacity is only produced by the chemical composition of the slurry together with the sintering process in the final sintered ceramic. Therefore, the optical property of translucency or opacity is the result of the sintering process.

[0007] The opaque slurry includes, for example, yttrium-stabilized Zr 2 particles having a Y 2 O 3 content of 1.5 to 4.5 mol%, preferably 2 to 4 mol%, and particularly preferably 2.5 to 3.5 mol%.

[0008] The translucent slurry includes, for example, yttrium-stabilized ZrO 2 particles, which have a Y 2 O 3 content of 4.0 to 8.0 mol%, preferably 4.0 to 7.0 mol%, and particularly preferably 4.0 to 6.0 mol%.

[0009] In a technically advantageous embodiment of the method, the yttrium content of the translucent ceramic slurry is higher than that of one of the opaque ceramic slurries. This achieves, for example, the technical advantage of producing regions of different translucencies in a sintered dental restoration using particularly suitable slurries, with high tooth enamel and low dentin core.

[0010] In a technically advantageous embodiment of the method, the dentin core of the dental restoration is additionally jet-printed using a colored translucent slurry. This achieves, for example, the technical advantage of further improving the natural appearance of the dental restoration.

[0011] In a further technically advantageous embodiment of the method, the different colors of the slurry of the dentin core form a color scheme with a limited color space. The limited color space is suitable for coloring dental restorations. If a color scheme is used to cover the entire color space, a larger number of printheads is required. The production of these different slurries is also complex. This has, for example, the technical advantage that the number of printheads can be reduced and the amount of slurry in reserve can be reduced.

[0012] In a further technically advantageous embodiment of the method, regions of the dental restoration with intermediate color values and / or intermediate translucency values are produced by mixing at least two slurries. This achieves, for example, the technical advantage that a dental restoration can be produced with color values and / or translucency values that do not correspond to those of the slurries used.

[0013] In another technically advantageous embodiment of the method, the mixing is carried out by generating a two-dimensional dithering pattern for the layers of the dental restoration. The dithering pattern indicates how the different slurries are arranged in a two-dimensional plane in order to generate intermediate color values and / or intermediate translucency values. This also achieves, for example, the technical advantage that a dental restoration with a natural appearance can be produced.

[0014] In a further technically advantageous embodiment of the method, different two-dimensional dithering patterns are used in successive layers of the dental restoration. This achieves, for example, the technical advantage of preventing the formation of stripes or moiré patterns in the dental restoration.

[0015] In a further technically advantageous embodiment of the method, a printhead is assigned to each slurry holding container. This achieves, for example, the technical advantage that a dental restoration can be printed quickly and easily.

[0016] In a further technically advantageous embodiment of the method, the dental prosthesis is sintered in a sintering furnace. This achieves, for example, the technical advantage that dental prostheses with high strength can be produced.

[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 prosthesis. 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 of 25 °C to 200 °C, preferably 30 °C to 180 °C, and particularly preferably 40 °C to 150 °C. Additionally, the humidity can be adjusted between 10% and 90%, preferably 15% and 85%, and particularly preferably 20% and 80%. Debinding is usually carried out at the following temperatures: 50 °C to 600 °C, preferably between 100 °C and 600 °C, and particularly preferably 200 °C - 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] According to a second aspect, this technical task is solved by a production device for producing dental prostheses by inkjet printing, the production device comprising: a plurality of receiving containers for receiving opaque ceramic slurries for dentin cores having different colors from one another; and at least one receiving container for receiving a translucent ceramic slurry for tooth enamel. The production device uses a three-dimensional multi-color printing process by means of material jetting of ceramic slurries. This production equipment achieves the same technical advantages as the method according to the first aspect.

[0019] In a technically advantageous embodiment of the production device, the production device includes a print head for each receiving container. This achieves, for example, the technical advantage that dental prostheses can be printed quickly and easily.

[0020] In a further technically advantageous embodiment of the production device, the production device includes at least two receiving containers for the slurries, such as five, six, seven, or eight receiving containers for the slurries. This achieves, for example, the technical advantage that realistic dental prostheses can be produced using a small number of print heads and receiving containers.

[0021] In a further technically advantageous embodiment of the production device, the different colors of the slurries of the dentin cores form a color scheme with a limited color space. This achieves, for example, the technical advantage that a smaller number of print heads or receiving containers can be used compared to a complete color matching scheme.

[0022] In a further technically advantageous embodiment of the production device, the production device includes a dithering module for calculating intermediate color values or intermediate translucency values by mixing at least two slurries. This achieves the technical advantage that, for example, dental restorations can be produced having color values or translucency values that do not correspond to the color values or translucency values of the slurries used.

[0023] In a further technically advantageous embodiment of the production device, the dithering module is configured to use different two-dimensional dithering patterns in successive layers of the dental restoration. This achieves the technical advantage of, for example, preventing the formation of streaks or moiré patterns in the dental restoration.

[0024] According to a third aspect, this technical task is solved by an inkjet printing system that includes a production device for producing a dental restoration by inkjet printing; at least one of a plurality of opaque ceramic slurries for printing a dentin core having different colors from each other; and a translucent ceramic slurry for printing tooth enamel. The inkjet printing system achieves the same technical advantages as the method according to the first aspect.

[0025] In a technically advantageous embodiment of the inkjet printing system, at least one of the plurality of opaque ceramic slurries and / or the translucent ceramic slurry is stored in a container. This achieves the technical advantage that, for example, the opaque ceramic slurry and / or the translucent ceramic slurry can be stored reliably.

[0026] In a further technically advantageous embodiment of the inkjet printing system, the container is replaceable. This achieves the technical advantage that, for example, the solution can be easily exchanged. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Exemplary embodiments of the present invention are shown in the drawings and described in more detail below, wherein:

[0028] Figure 1 A diagram showing different regions of an incisor is shown;

[0029] Figure 2 A schematic diagram of a dental restoration is shown;

[0030] Figure 3 A schematic diagram of a production device for producing a dental restoration by inkjet printing is shown, and

[0031] Figure 4 A block diagram of a method for producing a dental restoration by inkjet printing is shown. DETAILED DESCRIPTION

[0032] Figure 1Illustration showing different regions of tooth 105. Tooth 105 includes an inner dentin core 101 and an outer tooth enamel 103. There is an intermediate region 115 between the dentin core 101 and the tooth enamel 103.

[0033] The opaque, i.e., non-transparent, dentin core 101 is responsible for the basic coloring of tooth 105. This shines through the enamel 103 at the incisal edge. Tooth enamel 103 is translucent. Translucency is the partial light transmittance of an object. In order to make a dental prosthesis look as realistic as possible, this structure of tooth 105 is also used for artificial dental prostheses. For this purpose, materials with different optical properties are used in the production of dental prostheses.

[0034] Figure 2 Schematic illustration of a dental prosthesis 100 is shown. Dental prosthesis 100 serves as a dental prosthesis and is formed, for example, by a dental bridge, a dental crown, a veneer, an inlay, an onlay, an abutment, a complete or partial prosthesis. Dental prosthesis 100 is constructed, for example, with ceramic slurries of different colors, which may contain small amounts of coloring components such as 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 。For this purpose, during the spatial production of dental prosthesis 100 by means of an inkjet printing process, these slurries are selectively used for the respective regions.

[0035] Dental prosthesis 100 is constructed from successive layers printed on top of each other. The ceramic powder of the slurry may already be provided in a predetermined color and translucency. Mixing these slurries results in the target tooth color and target translucency of dental prosthesis 100 in the corresponding spatial regions.

[0036] After selectively applying a layer of slurry using an inkjet printing process, the layer is dried without cracking by evaporating water or a solvent. What remains is a porous white body layer with a layer thickness of 1 μm to 50 μm and a density of at least 2.5 g / cm 3 。This process is repeated until the entire dental prosthesis 100 is spatially constructed in layers.

[0037] Figure 3A schematic view of a production apparatus 200 for producing a dental prosthesis 100 by inkjet printing of an aqueous or solvent-based paste 109 is shown. The pre-colored paste 109 is processed to additionally produce ceramic, dental multi-material and multi-color prostheses 100 by means of inkjet printing.

[0038] The production apparatus 200 includes a plurality of receiving containers 107, in each of which a ceramic paste 109 having different optical properties for a dentin core 101 is arranged. Additionally, the production apparatus 200 includes at least one receiving container 107 in which a translucent ceramic paste 109 for producing tooth enamel 103 is received. A production apparatus for producing a dental prosthesis by inkjet printing; at least one of a plurality of opaque ceramic pastes for printing dentin; and a translucent ceramic paste for printing tooth enamel together form an inkjet printing system.

[0039] The ceramic pastes 109 are each applied drop by drop in a plurality of layers by means of a designated print head 111 in order to spatially layer build the dental prosthesis 100. The print head 111 can be moved in two directions so that the paste 109 can be printed at any position. For selective material application, a paste 109 having a droplet volume of generally 10 to 100 pL is used, the use of which eliminates a time-consuming debinding process. Electro-controlled piezoelectric elements are used to eject the droplets. Alternatively, a bubble jet process can also be used.

[0040] The production apparatus 200 provides a reduced number of pre-colored and yttrium-doped pastes 109 to minimize the number of print heads 111 and still achieve aesthetic and functional results of the dental prosthesis 100.

[0041] The desired tooth color is composed and mixed by the pre-colored paste 109. A subtractive color system is used, which spans a limited dental color space (dental color gamut). Then, these pre-colored pastes 109 are created by color mixing, three-dimensional halftoning or dithering at various ratios in a specific dental color gamut that covers common tooth colors, but not all colors.

[0042] The 3D dithering algorithm executed by a dithering module is used to selectively apply pastes 109 of different colors in one layer. 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. 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 processing units (MPU), a dedicated circuit for implementing functions or 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).

[0043] During jittering, slurries 109 of different colors are selectively applied at a certain rate and in a two-dimensional printing pattern on a printing plane using an inkjet printing process. A 3D jittering algorithm also calculates the application of different two-dimensional jitter patterns in multiple layers 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 dithering in a specific dental color space (gamut) that covers common tooth colors but not all general colors.

[0044] Figure 4 A block diagram of a method for producing a dental prosthesis 100 by inkjet printing is shown. In step S101, a dentin core 101 of the dental prosthesis 100 is inkjet printed using a plurality of opaque ceramic slurries 109 having different colors from each other. In step S102, tooth enamel 103 of the dental prosthesis 100 is inkjet printed by means of a translucent ceramic slurry 109. Then, the thus constructed dental prosthesis 100 is sintered in a sintering furnace.

[0045] There are slurries 109 for constructing tooth enamel 103 of the incisal edge and slurries 109 for constructing the dentin core 101. The difference between these slurries 109 lies in the translucency of the materials, and the translucency of tooth enamel 103 is many times higher than that of the dentin core 101.

[0046] For example, the slurries 109 can be used in seven different basic color combinations, two of which are for tooth enamel 103, and an additional support material 110 is used for the support structure. The support material is made of organic components such as wax, paraffin, or carbon black slurry.

[0047] 1 White, highly translucent

[0048] (Incisal edge / area), higher Y doping content

[0049] 2 Yellow-brown, highly translucent

[0050] (Incisal edge / area), higher Y doping content

[0051] 3 White, opaque, high strength

[0052] (Dentin area)

[0053] 4 Pink, translucent, strong

[0054] (Dentin area, also applicable to incisal edge detailing)

[0055] 5 Grey, translucent, strong

[0056] (Dentin area, also applicable to the detailed treatment of the incisal edge)

[0057] 6 Yellow, translucent, strong

[0058] (Dentin area)

[0059] 7 Yellowish-brown, opaque, high strength

[0060] (Dentin area)

[0061] 8 Support material

[0062] In another embodiment, only a separate translucent slurry 109 and five different slurries 109 are provided to color the dentin core 101. This has the technical advantage that seven printheads 111 (including the support material 110) are sufficient.

[0063] 1 Incisal edge, highly translucent (8 - 9Y)

[0064] (Incisal edge / area)

[0065] 2 White, opaque, high strength

[0066] (Dentin area)

[0067] 3 Pink, translucent, strong

[0068] (Dentin area, also applicable to the detailed treatment of the incisal edge)

[0069] 4 Grey, translucent, strong

[0070] (Dentin area, also applicable to the detailed treatment of the incisal edge)

[0071] 5 Yellow, translucent, strong

[0072] (Dentin area, also applicable to the detailed treatment of the incisal edge)

[0073] 6 Yellowish-brown, opaque, high strength

[0074] (Dentin area)

[0075] 7 Support material

[0076] The dentin core 101 is responsible for the basic color matching and emits light through the tooth enamel 103 of the incisal edge. In extreme cases, the incisal edge is colorless and highly translucent. For this purpose, specific pre-colored and yttrium-doped slurries 109 are provided for coloring and for the tooth-specific core / shell construction (dentin / incisal edge).

[0077] In ZrO 2In the case of the paste 109, different yttrium-doped ceramic powders (3 mol% yttrium - 3Y-TZP, 4 mol% yttrium - 4Y-TZP, 5 mol% yttrium - 5Y-TZP) can also be used for different strengths. Yttrium doping also affects the degree of translucency. Different yttrium-doped ceramic powders have different properties.

[0078] 3Y-TZP = low translucency / high strength

[0079] 4Y-TZP = medium translucency / medium strength

[0080] 5Y-TZP = high translucency / low strength

[0081] However, if different pre-colored pastes 109 are used and all of these pre-colored pastes also have different translucencies and / or mechanical properties, then each of these pastes 109 will use a separate print head 111. For example, if a general four-color scheme is used to cover the entire color space and pastes with different translucencies or strengths are also used in three variants, then 12 print heads are required to contain 3 x 4 = 12 pastes 109. The production of these different pastes 109 is also complex.

[0082] The pre-colored pastes 109 with different yttrium contents should be adjusted to obtain a uniform sintering behavior. By adding sintering activators or sintering inhibitors in a targeted manner, the sintering behavior of each layer can be adjusted. Sintering activators are, for example, Zn 2+ or Mg 2+ ions, which can be added to the coloring solution in the form of soluble salts (such as Zn(NO 3 ) 2 *6H 2 O or Mg(NO 3 )*H 2 O). Sintering inhibitors are, for example, Al 3+ or Y 3+ , which can be added to the coloring solution in the form of soluble salts (such as Al(NO 3 ) 3 *9H 2 O or Y(NO 3 ) 3 *6H 2 O).

[0083] 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.

[0084] All method steps can be implemented by a device suitable for performing each method step. All functions performed by the features of the subject matter can be method steps of a method.

[0085] The protection scope of the present invention is given by the claims and is not limited to the features explained in the description or shown in the drawings.

[0086] List of reference numerals

[0087] 100 Dental prosthesis

[0088] 101 Dentin core

[0089] 103 Tooth enamel

[0090] 105 Tooth

[0091] 107 Receiving container

[0092] 109 Slurry

[0093] 110 Support material

[0094] 111 Print head

[0095] 115 Intermediate region

[0096] 200 Production device.

Claims

1. A method for producing a dental restoration by jet printing, comprising the following steps: - jet printing a dentin core of the dental restoration using a plurality of opaque ceramic slurries having mutually different colors; as well as - Using a translucent ceramic slurry to jet print the tooth enamel of the dental restoration.

2. The method according to claim 1, wherein: The yttrium content of the translucent ceramic slurry is higher than the yttrium content of one of the opaque ceramic slurries.

3. A method according to any one of the preceding claims, wherein: The dentin core of the dental restoration was additionally jet printed using a colored translucent slurry.

4. A method according to any one of the preceding claims, wherein: The different colors of slurry used for the dentin core form a color scheme with a limited color space.

5. A method according to any one of the preceding claims, wherein: Regions of the dental restoration having intermediate color values ​​and / or intermediate translucency values ​​are produced by mixing at least two slurries.

6. The method according to claim 5, wherein: The mixing is performed by generating a two-dimensional dithering pattern for the layers of the dental restoration.

7. The method according to claim 6, wherein: Different two-dimensional dithering patterns are used in successive layers of the dental restoration.

8. A method according to any one of the preceding claims, wherein: A print head is assigned to each slurry containing container.

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

10. The method according to any one of the preceding claims, wherein: The dental restoration is sintered in a sintering furnace.

11. A production device for producing a dental restoration by jet printing, comprising: - a plurality of receiving containers for receiving opaque ceramic slurries having dentin cores of different colors from each other; and - at least one containing container for containing a translucent ceramic slurry for tooth enamel.

12. The production device according to claim 11, wherein: The production device comprises one print head for each receiving container.

13. Production plant according to one of claims 10 to 12, wherein: The different color pastes of the dentin core form a color scheme with a limited color space.

14. Production plant according to one of claims 10 to 13, wherein: The production device comprises a dithering module for calculating an intermediate color value and / or an intermediate translucency value by mixing at least two slurries.

15. The production device according to claim 14, wherein: The dithering module is configured to use different two-dimensional dithering patterns in successive layers of the dental restoration.

16. Inkjet printing system, including: - a production device for producing dental restorations by inkjet printing; - at least one of a plurality of opaque ceramic slurries for printing dentin cores having colors different from each other; as well as -Translucent ceramic slurry for printing tooth enamel.

17. The jet printing system according to claim 16, wherein: At least one of the plurality of opaque ceramic slurries and / or the translucent ceramic slurry is stored in a container.

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

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