METHOD FOR PRODUCING A DENTAL RESTORATION

Description

[0001] The present invention relates to a method for producing a dental restoration and a manufacturing device for producing a dental restoration.

[0002] In the digital fabrication of crowns and bridges, standard load cases are assumed for these crowns and bridges. This either limits the number of bridge units or oversizes these components in terms of wall thickness. This results in the mechanical properties of the materials used being many times higher than the actual loads.

[0003] The document US 2015 / 320525 A1 relates to methods for producing dental prostheses in which a powder of a dental material is selectively melted to produce a three-dimensional dental prosthesis with a desired physical geometry and one or more functionally graded mechanical properties.

[0004] US 2007 / 015110 A1 relates to methods and materials used to manufacture dental prostheses. An insert molding process can be used to place a metal or fiber reinforcement insert or element into a prosthetic component.

[0005] It is the technical object of the present invention to improve the production of dental restorations.

[0006] This technical problem is solved by the subject matter according to the independent claims. Technically advantageous embodiments are the subject matter of the dependent claims, the description, and the drawings.

[0007] According to a first aspect of the invention, the technical problem is solved by a method for producing a dental restoration, comprising the steps of determining a first spatial region of the dental restoration that is exposed to a higher load than a second spatial region of the dental restoration; and producing the dental restoration in the first spatial region with a different production material than in the second spatial region, wherein the production material is doped differently in the first spatial region than in the second spatial region.

[0008] This provides the technical advantage, for example, that a sintering process can be carried out without sintering distortion, and the manufacturing material exhibits varying strength values. In addition to the sintering properties, the mechanical properties, optical properties, and aging resistance can also be adjusted through doping. This process allows for optimal utilization of material properties and a broader range of indications. Stress peaks within the dental restoration can be absorbed by appropriate material adaptation. The dental restoration can therefore be manufactured using less material.

[0009] In a technically advantageous embodiment of the method, the first spatial region is determined by the internal voltage in this spatial region being above a predetermined value. This achieves, for example, the technical advantage that the first spatial region can be easily defined.

[0010] In another technically advantageous embodiment of the method, the load is calculated using a finite element method. This achieves the technical advantage, for example, that the load within the dental restoration can be calculated with high accuracy.

[0011] In another technically advantageous embodiment of the method, predetermined forces are applied to the dental restoration for the finite element method. For example, the calculations can be based on worst-case scenarios, in which the maximum expected forces act at the most unfavorable points of the dental restoration. This achieves the technical advantage, for example, that the dental restoration can be calculated with high strength (biaxial strength, fracture toughness).

[0012] In a further technically advantageous embodiment of the method, the manufacturing material for the first and / or second spatial region is selected based on a calculated load. This achieves, for example, the technical advantage of achieving different strengths for the spatial regions and adapting them to the load.

[0013] The following values are commonly used as suitable strength values (flexural strength + fracture toughness) for differently yttrium-doped zirconium dioxide materials: material 3Y-TZP 4Y-TZP 5Y-TZP Biaxial flexural strength [MPa] 1000 ± 200(*) 750 ± 100(*) 600 ± 50(*) Fracture toughness [MPa√m] 5.00 ± 0.25 3.75 ± 0.25 2.40 ± 0.25

[0014] In a further technically advantageous embodiment of the method, a manufacturing material with a higher strength is used in the first spatial region than in the second spatial region. This achieves the technical advantage, for example, of being able to reduce the wall thickness in these regions.

[0015] In another technically advantageous embodiment of the method, the dental restoration is manufactured using a three-dimensional printing process. This achieves the technical advantage that the dental restoration can be manufactured efficiently.

[0016] In another technically advantageous embodiment of the method, the three-dimensional printing process uses free-jet material deposition. This achieves the technical advantage, for example, that the production materials can be easily arranged in the respective spatial areas.

[0017] According to a second aspect of the invention, the technical problem is solved by a manufacturing device for producing a dental restoration, comprising a determining device for determining a first spatial region of the dental restoration that is exposed to a higher load than a second spatial region of the dental restoration; and a manufacturing device for producing the dental restoration in the first spatial region with a different manufacturing material than in the second spatial region, wherein the manufacturing device is designed to dope the manufacturing material differently in the first spatial region than in the second spatial region. This also achieves the technical advantage, for example, that a sintering process can be carried out without sintering distortion. The manufacturing device achieves the same technical advantages as the method according to the first aspect.

[0018] In a technically advantageous embodiment of the manufacturing device, the determining device is configured to determine the first spatial region by determining that the internal voltage in this spatial region is above a predetermined value. This also achieves the technical advantage, for example, that the first spatial region can be easily defined.

[0019] In a further technically advantageous embodiment of the manufacturing device, the determination device is designed to calculate the load using a finite element method. This also achieves the technical advantage, for example, that the load can be calculated with high accuracy.

[0020] In a further technically advantageous embodiment of the manufacturing device, the manufacturing device is configured to select the manufacturing material for the first and / or second spatial region based on a calculated load. This also achieves the technical advantage, for example, of simplifying the production of the dental restoration.

[0021] In a technically advantageous embodiment of the manufacturing device, the manufacturing device comprises a 3D printer. This also achieves the technical advantage, for example, that the production of the dental restoration can be carried out efficiently.

[0022] Embodiments of the invention are illustrated in the drawings and are described in more detail below.

[0023] They show: Fig. 1 shows a schematic view for producing a dental restoration; Fig. 2 shows a schematic view of a manufacturing device for producing a dental restoration; and Fig. 3 shows a block diagram of a method for producing the dental restoration.

[0024] Fig. 1 shows a schematic view for the production of a dental restoration 100. The dental restoration 100 is, for example, a crown, a bridge, a partial or full denture.

[0025] To better utilize the mechanical properties of the manufacturing materials 107-1 and 107-2, predefined load cases for the dental restoration 100 are first simulated using FEM (finite element method) software. The FEM software can calculate internal force curves and stresses based on a three-dimensional model of the dental restoration 100 in order to determine weak points in the dental restoration 100. To facilitate identification of under- or over-stressed spatial regions (subvolumes), these can be marked with specific colors. For example, in this way, spatial regions 101-1 within the dental restoration 100 can be determined in which an internal stress exceeds a predefined value.

[0026] For this purpose, the dental restoration 100 can be subjected to targeted forces that may occur during use. These forces act on the weakest points of the dental restoration 100. If the dental restoration 100 is a bridge, for example, the maximum force occurring is applied to the center of the bridge. The FEM software then calculates how the stresses are distributed within the bridge. In this way, spatial regions 101-1 can be determined where the stresses are particularly high.

[0027] However, forces that actually occur can also be determined based on a real bite situation using a pressure mat. The pressure mat measures the forces that occur when the teeth clench. The determined forces can then be used by the FEM software for the dental restoration 100 to calculate the internal stress distribution within the dental restoration 100 under real-life conditions.

[0028] The FEM software is also capable of providing recommendations for material adjustments, as it knows the mechanical properties of the various available manufacturing materials 107-1 and 107-2. Since the under- and / or over-determined spatial areas 101-1 and 101-2 in the dental restoration 100 are known through the FEM analysis, appropriate corrective measures can be taken. This minimizes the probability of component failure and provides a load guarantee for the customer. Furthermore, the software enables a plausibility check of the manufacturing materials 107-1 and 107-2 used.

[0029] Fig. 2shows a schematic view of a manufacturing device 200 for manufacturing the dental restoration 100. The manufacturing device 200 comprises a determining device 103 for determining a first spatial region 101-1 of the dental restoration 100 that is subjected to a higher load than a second spatial region 101-2 of the dental restoration 100.

[0030] The determination device 103 comprises, for example, a processor and a memory on which FEM software is executed. The determination device 103 is formed, for example, by a computer.

[0031] The FEM software running on the determination device 103 uses a digital model of the dental restoration 100 to calculate those spatial regions in which higher mechanical loads occur than in other spatial regions. In this way, the digital model of the dental restoration 100 can be divided into different spatial regions 101-1 or 101-2. Three or more spatial regions with different mechanical loads can also be defined within the dental restoration 100. A separate manufacturing material can be used for each of these spatial regions.

[0032] Subsequently, the determination device 103 sends control data to a manufacturing device 105, which is used to manufacture the dental restoration. Depending on the calculated loads, the determination device 103 can automatically assign the respective manufacturing materials 107-1 and 107-2 to different spatial areas 101-1 and 101-2. This can be done because the determination device 103 knows the properties of the available manufacturing materials.

[0033] The manufacturing device 105 uses a different manufacturing material 107-1 in the first spatial region 101-1 than in the second spatial region 101-2. This manufacturing material 107-1 may have a higher strength than the other manufacturing material 107-2.

[0034] The manufacturing device 103 uses, for example, an additive manufacturing process in which a raw material is selectively deposited in the form of droplets in layers, such as polyjet modeling and multijet modeling. The manufacturing device 105 includes, for example, a first container 109-1 for the first manufacturing material 101-1 and a second container 109-2 for the second manufacturing material 107-2. The control signals from the determining device cause the manufacturing device 105 to automatically use the assigned manufacturing material 107-1 or 107-2 when printing the respective spatial region 101-1 and 101-2.

[0035] The manufacturing device 200 can reduce the isotropy of the load distribution within the dental restoration 100. A different, such as a stronger, manufacturing material 107-1 can be used for a more highly stressed or loaded spatial area 101-1, such as zirconia with 3 weight percent yttria (3YTZP) instead of zirconia with 5 weight percent yttria (5YTZP).

[0036] If the same manufacturing material 107 were used for both spatial areas 101-1 and 101-2, this would require a thickening of the dental restoration 100, which is often undesirable for aesthetic and haptic reasons. The manufacturing device 200 enables a reduction in wall thickness in underloaded subvolumes for improved aesthetics.

[0037] This selective adjustment of the material allocation can be carried out within the framework of an additive multi-material manufacturing process in which a selective material deposition takes place freely in three-dimensional space, such as in a free-jet material deposition in poly or multi-jet modeling.

[0038] In 3D inkjet printing, for example, manufacturing materials 107-1 and 107-2 with a viscosity greater than 15 mPas, preferably greater than 150 mPas, and most preferably greater than 200 mPas can be jetted at a suitable processing temperature. Through the selective material application of material jetting, the smallest spatial regions 101-1, down to a size of a single voxel, can be constructed using different manufacturing materials 107-1 and 107-2.

[0039] If a user either changes the design of the dental restoration 100 or assigns other manufacturing materials 107-1 and 107-2 with different mechanical properties, this change can be made visible to the user. If the design and the manufacturing materials 107-1 and 107-2 are satisfactory, the user can start the print job for the dental restoration 100. This will then be automatically constructed with the respective manufacturing materials 107-1 and 107-2 in the respective spatial areas 101-1 and 101-2.

[0040] Fig. 3shows a block diagram of a method for manufacturing the dental restoration 100. In step S101, a first spatial region 101-1 of the dental restoration 100 is determined, which is subjected to a higher load than a second spatial region 101-2 of the dental restoration 100. In step S102, the dental restoration 100 is manufactured in the first spatial region 101-1 using a different manufacturing material 107-1 than in the second spatial region 101-2. The method can be applied to all spatial regions 101-1 and 101-2 of the dental restoration 100.

[0041] When processing zirconium oxide slurries, the sintering properties can be locally modified within a spatial area by selectively doping the material layer differently in the green compact stage. This leads to different strength ranges during the sintering process when using different manufacturing materials 107-1 and 107-2 in the final dental restoration 100. Selective doping is achieved, for example, by jetting an infiltration fluid into a previously applied and dried material layer. In addition to the sintering properties, the mechanical properties, optical properties, and aging resistance can also be adjusted through doping.

[0042] The method can identify spatial areas 101 in the dental restoration 100 that are either over-determined or should be enhanced.

[0043] Accordingly, other manufacturing materials 107-1 and 107-2 with different mechanical properties can be selectively and locally assigned. This allows crowns or bridges made of final manufacturing materials 107-1 and 107-2 (composite or ceramic) to be adapted to the individual load cases.

[0044] The scope of indications can be expanded, and the resulting loads can be quantified and visualized. The dental technician can be assisted in modeling the dental restoration by displaying spatial areas 101 where the wall thicknesses can be reduced or should be increased. By assigning different manufacturing materials 107-1 and 107-2 with different mechanical properties to the respective spatial areas 101, load peaks can be absorbed without additionally increasing the wall thickness.

[0045] All features explained and shown in connection with individual embodiments of the invention can be provided in different combinations in the subject matter according to the invention in order to simultaneously realize their advantageous effects.

[0046] All method steps can be implemented by devices suitable for performing the respective method step. All functions performed by physical features can be a method step of a method.

[0047] The scope of the present invention is given by the claims and is not limited by the features explained in the description or shown in the figures. LIST OF REFERENCE SYMBOLS

[0048] 100Dental Restoration 101Spatial Area 103Determination Device 105Fabrication Device 107Fabrication Material 109Container

Claims

1. A non-therapeutic method of producing a dental restoration (100), comprising the steps of: - determining (S101) a first spatial region (101-1) of the dental restoration (100) that is subject to a higher mechanical load than a second spatial region (101-2) of the dental restoration (100); and - producing (S102) the dental restoration (100) in the first spatial region (101-1) with a different production material (107-1) than in the second spatial region (101-2); characterized in that the production material (107-1) in the first spatial region (101-1) is doped differently than in the second spatial region (101-2).

2. The method according to claim 1, wherein the first spatial region (101-1) is determined by the internal stress in this spatial region (101-1) being above a predetermined value.

3. The method according to claim 2, wherein the load is calculated using a finite element method.

4. The method according to claim 3, wherein predetermined forces are applied to the dental restoration (100) for the finite element method.

5. The method according to any one of the preceding claims, wherein the production material (107-1, 107-2) for the first and / or second spatial region (101-1, 101-2) is selected based on a calculated load.

6. The method according to any one of the preceding claims, wherein in the first spatial region (101-1) a production material (107-1) having a higher strength than in the second spatial region is used.

7. The method according to any one of the preceding claims, wherein the production of the dental restoration (100) is performed by means of a three-dimensional printing process.

8. The method according to claim 7, wherein the three-dimensional printing process uses free-jet material deposition.

9. A production device (200) for producing a dental restoration (100), comprising: - a determination device (103) for determining a first spatial region (101-1) of the dental restoration (100) which is subject to a higher mechanical load than a second spatial region (101-2) of the dental restoration (100); and - a production apparatus (105) for producing the dental restoration (100) in the first spatial region (107-1) with a different production material (107-1) than in the second spatial region (101-2), characterized in that the production apparatus (105) is configured to dope the production material (107-1) in the first spatial region (101-1) differently than in the second spatial region (101-2).

10. The production device (200) according to claim 9, wherein the determination device (103) is configured to determine the first spatial region (101-1) by the internal stress being above a predetermined value in this spatial region (101-1).

11. The production device (200) according to claim 10, wherein the determination device (103) is configured to calculate the load using a finite element method.

12. The production device (200) according to any one of claims 9 to 11, wherein the production apparatus (105) is configured to select the production material (107-1, 107-2) for the first and / or second spatial region (101-1, 101-2) based on a calculated load.

13. The production device (200) according to any one of claims 9 to 12, wherein the production apparatus (105) comprises a 3D printer.