Method for manufacturing a dental prosthesis

Abstract

The present invention relates to a method for manufacturing a dental prosthesis, comprising the following steps: rendering (S101) a first digital dental model with a first material combination to generate a first actual data set representing the optical properties of the first digital dental model; determining (S102) a first deviation between a target data set and the first actual data set; rendering (S103) a second digital dental model based on a second material combination to generate a second actual data set representing the optical properties of the second digital dental model; determining (S104) a second deviation between the target data set and the second actual data set; and manufacturing (S105) a dental prosthesis based on the first digital dental model when the first deviation is less than the second deviation, and manufacturing a dental prosthesis based on the second digital dental model when the second deviation is less than the first deviation.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a dental prosthesis, a computer device for manufacturing a dental prosthesis, and a computer program. Background Art

[0002] Dental prostheses can be constructed from a variety of different materials to reproduce the appearance of natural teeth as faithfully as possible. However, choosing the appropriate materials is complex and can lead to suboptimal results. It is generally unclear how the optical properties of a dental prosthesis are achieved through the corresponding prosthetic materials. Therefore, it is difficult to manufacture new dental prostheses with the desired optical properties.

[0003] The technical task of the present invention is to determine a material combination for a dental prosthesis that corresponds to the desired natural appearance. Summary of the Invention

[0004] This technical task is solved by the subject matter of the independent claims. Technically advantageous embodiments are the subject matter of the dependent claims, the description, and the drawings.

[0005] According to a first aspect, this technical problem is solved by a method for manufacturing a dental prosthesis, the method comprising the steps of: rendering a first digital dental model with a first material combination to generate a first actual data set representing the optical properties of the first digital dental model; determining a first deviation between a target data set and the first actual data set; rendering a second digital dental model with a second material combination to generate a second actual data set representing the optical properties of the second digital dental model; determining a second deviation between the target data set and the second actual data set; and manufacturing a dental prosthesis based on the first digital dental model when the first deviation is less than the second deviation, and manufacturing a dental prosthesis based on the second digital dental model when the second deviation is less than the first deviation.

[0006] By varying the distribution of different prosthetic materials within the internal structure of the dental model, this method can be used to pre-calculate the appearance of the dental prosthesis to be produced. By comparing the optical appearance of the corresponding actual data set with a specified target data set, the best result can be determined from a large number of combinations. The target data set may already be pre-determined based on adjacent teeth. In this way, the material combination and distribution for manufacturing a dental prosthesis can be determined. The external shape and internal structure of the dental prosthesis can be specified.

[0007] In a technically advantageous embodiment of this method, the first digital dental model and the second digital dental model reproduce the same spatial geometry. This has technical advantages, for example, the process can be performed with higher accuracy.

[0008] In another technically advantageous embodiment of the method, the rendering of the first digital tooth model is performed by a first processor and the rendering of the second digital tooth model is performed by a second processor. This has technical advantages such as, for example, the rendering steps can be performed simultaneously and the method can be performed faster.

[0009] In another technically advantageous embodiment of the method, the rendering of the first digital tooth model and the rendering of the second digital tooth model are performed in parallel. This also has technical advantages such as, for example, the rendering steps can be performed simultaneously and the method can be performed faster.

[0010] In another technically advantageous embodiment of the method, the first and / or second deviation is calculated based on the Euclidean distance between the target data set and the actual data set or based on the spectral distance between the target data set and the actual data set. This also has technical advantages such as, for example, the deviation can be calculated with high precision.

[0011] In another technically advantageous embodiment of the method, the first and / or second material combination includes at least two different prosthetic materials. This also has technical advantages such as, for example, obtaining a tooth restoration with as natural an appearance as possible.

[0012] In another technically advantageous embodiment of the method, the spatial structure of the first and / or second digital tooth model is predefined. This has technical advantages such as, for example, the structure of the digital tooth model remains constant and only the material combination changes, which shortens the calculation time of the method.

[0013] In another technically advantageous embodiment of the method, the rendering is performed based on the color value, reflection value, transmission value, and / or absorption value of the respective prosthetic material. This has the following technical advantages such as, for example, performing highly accurate rendering, which faithfully reproduces the subsequent appearance of the tooth restoration.

[0014] In another technically advantageous embodiment of the method, the optical properties of the mucous layer, composite layer, adhesive layer, and / or the color impression of the preparation are also considered during rendering. This has the following technical advantages such as, for example, achieving a more realistic appearance during rendering and considering two materials subsequently used for bonding and preparing the tooth restoration.

[0015] In another technically advantageous embodiment of the method, the specific quantity of the prosthetic material is determined in advance and the method is repeated for all possible material combinations. The individual rendering steps can be performed in parallel. This has the following technical advantages such as, for example, the tooth restoration can be adapted as precisely as possible.

[0016] In a further technically advantageous embodiment of the method, the material combination selected for manufacturing is the material combination with the smallest deviation between the target data set and the corresponding actual data set. This has the following technical advantages, for example, optimal results are achieved for a given prosthetic material.

[0017] In a further technically advantageous embodiment of the method, the digital tooth model has a predetermined external shape and a predetermined internal structure. This has the following technical advantages, for example, improving the calculation basis.

[0018] In a further technically advantageous embodiment of the method, the target data set is obtained based on natural teeth. This has the following technical advantages, for example, the dental prosthesis can be adapted to the natural teeth.

[0019] In a further technically advantageous embodiment of the method, the target data set reproduces the optical properties and / or geometry of the natural teeth. This has the following technical advantages, for example, further improving the fidelity of the dental prosthesis.

[0020] According to a second aspect, the technical problem is solved by a computer device for manufacturing a dental prosthesis, the computer device comprising a manufacturing device adapted to execute the method according to the first aspect. Thus, the same technical advantages as those achieved by the method according to the first aspect are realized.

[0021] According to a third aspect, the technical problem is solved by a computer program comprising instructions for causing the computer device according to the second aspect to execute the method steps according to the first aspect. Thus, the same technical advantages as those achieved by the method according to the first aspect are realized.

[0022] Examples of embodiments of the present invention are shown in the drawings and described in more detail below. Description of the Drawings

[0023] The drawings show:

[0024] Figure 1 : A schematic diagram of a digital tooth model;

[0025] Figure 2 : A representation of the comparison between the target data set and the actual data set.

[0026] Figure 3 : A schematic diagram of calculating the deviation between the target data set and the actual data set.

[0027] Figure 4 : A block diagram of the method for producing a dental prosthesis. Detailed Description of the Embodiments

[0028] Figure 1A schematic diagram of digital dental models 200-1 and 200-2 of a dental prosthesis 100 is shown. The subsequent external shape and internal space structure of the dental prosthesis 100 are specified by the digital dental models 200-1 and 200-2. For this purpose, the external shape can be generated in a CAD program. The internal space structure can be calculated or obtained from a database, for example, derived from the structure of natural teeth, or calculated from the external shape of the dental prosthesis 100 or natural teeth. Given the predetermined external shape of the dental prosthesis 100, the internal layered structure can be defined by the dental models 200-1 and 200-2, and restorative materials 201 and 203 with their own predetermined optical material parameters can be assigned to each individual layer. For the dental models, the appearance of the same residual tooth 207 or the same preparation of the tooth to be treated is assumed.

[0029] For example, the first dental model 200-1 reproduces the dental prosthesis 100 constructed by layering different restorative materials 201-1, 201-2, and 201-3. In the outer layer, the restorative material 201-1 is used, in the middle layer, the restorative material 201-2 is used, and in the inner layer, the restorative material 201-3 is used. The inner layer can also be an adhesive layer 209.

[0030] The second dental model 200-2 reproduces the same dental prosthesis 100, which is also constructed by layering different restorative materials 203-1, 203-2, and 203-3. However, the outer layer uses the restorative material 203-1, the middle layer uses the restorative material 203-2, and the inner layer uses the restorative material 203-3. The inner layer can also be an adhesive layer 209 with the adhesive material 203-3. Thus, the material combination of the first dental model 200-1 is different from the material combination of the second dental model 200-2.

[0031] The optical and physical properties of the corresponding assigned restorative materials 201-1, ……, 201-3, 203-1, ……, and 203-3 are known, such as color values, scattering values, reflection values, transmission values, and / or absorption values.

[0032] By using ray tracing for rendering (a light simulation process), the color and translucency of the dental prosthesis can be calculated based on the previously created dental model 200. In this way, the subsequent appearance and optical impression of the biomimetic dental prosthesis can be calculated from the dental model 200, such as a dental bridge, dental crown, partial crown, inlay, onlay, or veneer crown.

[0033] The rendering is performed using a physically correct simulation of the interaction of light with the planned dental prosthesis 100 and the restorative materials used. The known optical parameters of the individual restorative materials are used to generate a computer-aided view of the dental prosthesis 100.

[0034] For this purpose, it is also possible to consider existing natural tooth materials, such as the residual tooth on which the dental prosthesis 100 is to be placed. During rendering, an optical impression of the subsequent dental prosthesis 100 is calculated for the specified internal structure and the selected prosthesis material. For the rendering, a computer-aided calculation of the reflection, transmission, and absorption values in the visible light range at at least three wavelengths can be performed.

[0035] For this manufacturing method, a target data set is first determined. The target data set can be obtained by optically capturing and evaluating adjacent teeth. For this purpose, an electronic camera or a 3D scanner can be used to determine the color values, reflection, transmission, and / or absorption values, as well as the spatial shape or image of the natural tooth. Based on this data, the dental prosthesis 100 is planned to have as similar characteristics as possible and a spatial tooth model 200 is planned.

[0036] The target data set is used to compare the rendered appearance of the dental prosthesis 100 under variations of the prosthesis material assigned to the internal structure until the best approximation of the target data set is found.

[0037] Ideally, for the comparison, the rendering of the dental prosthesis 100 is performed from the same observation angle or perspective from which the target data set was obtained based on the natural tooth. Rendering can also be performed from different observation angles to improve the result. Rendering can be performed for any observation angle and any selectable environmental situation, such as a predefined lighting situation, taking into account adjacent teeth, the position of the dental prosthesis 100 in the oral cavity, or the shape and optical properties of the residual tooth to be prepared. Other influencing conditions can also be considered during rendering, such as the known optical data of the adhesive layer 209 (cement, composite, and / or adhesive).

[0038] Thus, rendering the digital tooth models 200-1 and 200-2 produces an actual data set that reproduces the optical properties of the digital tooth models 200-1 and 200-2.

[0039] Figure 2 A schematic diagram showing the deviation ΔE between the target data set DS-S and the actual data sets DS-I (DS-I-1, DS-I-2) is shown. The target data set DS-S is obtained, for example, by the electronic camera 101. S,I The digitally generated tooth model 200 includes data on the spatial geometry of the dental prosthesis 100 and the relevant prosthesis material from which the dental prosthesis 100 is to be manufactured, as well as the region in which the prosthesis material is to be arranged. The optical and physical properties of the prosthesis material required for rendering are known in the rendering software. These can be obtained from a parameter table that is continuously supplemented with new materials.

[0040]

[0041] ​The actual data set DS-I is obtained by rendering the digital tooth model 200 with the selected material combinations. During the rendering, the spatial geometry of the dental prosthesis 100 and the optical and physical properties of the various prosthetic materials encountered - including the adhesive material and the residual tooth or preparation (if applicable) - are taken into account.

[0042] The propagation of light in the tooth model 200 can be described by Maxwell's equations. For example, the rendering uses the radiative transfer equation (RTE), where the propagation medium is described by an absorption coefficient, a scattering coefficient, a refractive index, and a scattering phase function.

[0043] The digital tooth model 200 includes data on the spatial geometry of the dental prosthesis 100 and the internal structure, as well as the absorption coefficient, scattering coefficient, refractive index, and scattering phase function of the corresponding prosthetic materials 201 and 203 of the structure. When rendering based on the tooth model 200 using the above parameters, the scattering phase function can be numerically solved with any desired accuracy in a Monte Carlo simulation, where multiple photons propagate along random paths through the tooth model 200.

[0044] Thus, the actual data set DS-I of the appearance of the dental prosthesis 100 can be calculated by rendering, taking into account the materials used, the external shape and internal structure of the tooth model 200. The calculated actual data set DS-I can then be compared with the target data set DS-S that has been obtained based on the adjacent teeth. To simplify this comparison, it can be performed in a two-dimensional derivation (two-dimensional image). However, three-dimensional methods can also generally be used. The calculated value is used as a measure of the deviation ΔE S,I between.

[0045] Figure 3 shows a schematic diagram for calculating the deviation ΔE S,I between the target data set DS-S and the actual data set DS-I. For example, the data set DS-S includes a representation of the tooth in a given viewing angle. In contrast, the data set DS-I that has been rendered from the tooth model 200 includes a representation of the tooth model 200 in the same viewing angle. The two images from the target data set DS-S and the actual data set DS-I are scaled to the same size and placed adjacent to each other.

[0046] The Euclidean deviation ΔE S,I (ΔE1 S,I , ΔE2 S,I) It can be calculated by summing the differences in pixel color values along the comparison line 205 (e.g., in the L*a*b* color space). These comparison lines 205 can be moved arbitrarily, for example, by moving halves of the tooth together. However, generally speaking, the comparison lines 205 can also have different routes. The comparison can be made at the pixel level as the minimum resolution.

[0047]

[0048] The greater the difference in the color gradient along the comparison line 205, the greater the numerical deviation ΔE S,I will be. If there is a perfect color match between the target data set DS-S and the actual data set DS-I, the deviation ΔE S,I is zero. However, generally speaking, other methods can be used to calculate the deviation ΔE S,I , for example, based on spectral information.

[0049] Figure 4 FIG. shows a block diagram of a method for manufacturing a dental prosthesis 100. In a first step S101, a first digital tooth model 200-1 is rendered with a first material combination to generate a first actual data set DS-I-1 representing the optical characteristics of the first digital tooth model 200-1. In step S102, the first actual data set DS-I-1 is compared with the target data set DS-S to obtain a first deviation ΔE1 between the target data set DS-S and the first actual data set DS-I-1 S,I .

[0050] In step S103, a second digital tooth model 200-2 is then rendered with a second material combination to generate a second actual data set DS-I-2 representing the optical characteristics of the second digital tooth model 200-2. In step S104, the second actual data set DS-I-2 is also compared with the target data set DS-S to obtain a second deviation ΔE2 between the target data set DS-S and the second actual data set DS-I-1 S,I .

[0051] In step S105, if the first deviation ΔE1 S,I is less than the second deviation ΔE2 S,I , the dental prosthesis 100 is manufactured based on the first digital tooth model 200-1, or if the second deviation ΔE2 S,I is less than the first deviation ΔE1 S,I , the dental prosthesis 100 is manufactured based on the second digital tooth model 200-1.

[0052] This method can be used to render all possible material combinations of an entire system given geometrically. If all possible material combinations are calculated, for example, the best combination that is closest to the DS-S target data set and can best mimic the natural appearance of teeth can be determined. An objective target / actual comparison is obtained through this process, and the best allocation of the prosthetic material to the corresponding spatial regions of the dental prosthesis 100 is achieved through computer support (best fit).

[0053] If the internal structures of the tooth models 200-1 and 200-2 remain the same, the changes in the selected material combinations are calculated for individual layers. Then the best combination is determined.

[0054] The rendering of the digital tooth models 200-1 and 200-2 can be performed in parallel or simultaneously on different processors, thus obtaining the best results in a short time. The parallel rendering of different possible variations of the material allocation solves the problem of quickly finding a suitable dental prosthesis 100 for the patient in terms of optics. In this case, iterative calculations are not required.

[0055] The parallel calculation and simulation of all possible material combinations of a tooth model 200 with a given external shape and internal structure, and the subsequent comparison of the obtained actual data set with the target data set, can be used to determine the best feasible material combination.

[0056] Furthermore, in this method, it is feasible to use virtual prosthetic materials pre-assigned with predetermined optical properties to calculate the tooth models 200-1 and 200-2. Appropriate material combinations can also be determined thereby. Subsequently, the dental prosthesis 100 can be produced using real prosthetic materials whose properties are close to those of the virtual prosthetic materials 201 and 203. In this way, the desired overall impression of the prosthesis 100 can also be achieved.

[0057] This method can be used to determine the best selection and allocation of the prosthetic materials 201 and 203 before manufacturing the prosthesis 100 to create a multi-layered prosthesis 100 while ensuring the best aesthetic effect of the prosthesis 100. By performing rendering using the physical and optical parameters of the existing prosthetic materials, the dental prosthesis 100 can subsequently be manufactured using the best material combination.

[0058] Once the combination of materials has been determined, the dental prosthesis 100 can be manufactured using a 3D printing process or other suitable process with the corresponding prosthetic materials. In this case, a computer device can be used to perform the calculation steps and then a manufacturing device can be used to manufacture the dental prosthesis 100. To this end, the computer device executes a computer program that includes instructions for causing the computer device to perform the required program steps. The computer device includes a processor and a digital memory that stores data sets, as well as a computer program that executes the program steps and appropriately controls the manufacturing device. The manufacturing device is, for example, a 3D printer that prints the dental prosthesis 100 with various prosthetic materials. However, in general, other manufacturing devices that are capable of manufacturing dental prostheses with different prosthetic materials can be used.

[0059] 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 to simultaneously achieve their beneficial effects.

[0060] All method steps can be implemented by a device suitable for performing the corresponding method steps. All functions performed by the target features can be method steps of a method.

[0061] The protection scope of the present invention is given by the claims and is not limited by the features described in the specification or shown in the drawings.

[0062] Reference list:

[0063] 100 Dental prosthesis

[0064] 101 Electronic camera

[0065] 200 Tooth model

[0066] 201 Prosthetic material

[0067] 203 Prosthetic material

[0068] 205 Comparison line

[0069] 207 Residual tooth

[0070] 209 Fixing layer

[0071] DS-I Actual data set

[0072] DS-S Target data set

Claims

1. A method for manufacturing a dental prosthesis (100), comprising the following steps: - Rendering (S101) a first digital dental model (200-1) with a first material combination to generate a first actual data set DS-I-1 representing the optical properties of the first digital dental model (200-1); - Determine (S102) a first deviation ΔE1 between the target data set DS-S and the first actual data set DS-I-1 S,I ; - Rendering (S103) a second digital dental model (200-2) with a second material combination to generate a second actual data set DS-I-2 representing the optical properties of the second digital dental model (200-2); - Determine (S104) a second deviation ΔE2 between the target data set DS-S and the second actual data set DS-I-2 S,I ; And - If the first deviation ΔE1 S,I is less than the second deviation ΔE2 S,I , then the dental prosthesis (100) is manufactured (S105) based on the first digital tooth model (200-1), and if the second deviation ΔE2 S,I is less than the first deviation ΔE1 S,I , then the dental prosthesis (100) is manufactured (S105) based on the second digital tooth model (200-2). wherein the first deviation ΔE1 S,I is calculated based on the Euclidean distance between the target data set DS-S and the first actual data set DS-I-1 or based on the spectral distance between the target data set DS-S and the first actual data set DS-I-1, and / or wherein the second deviation ΔE2 S,I is calculated based on the Euclidean distance between the target data set DS-S and the second actual data set DS-I-2 or based on the spectral distance between the target data set DS-S and the second actual data set DS-I-2.

2. The method according to claim 1, wherein the first digital dental model (200-1) and the second digital dental model (200-2) represent the same spatial geometry.

3. The method according to claim 1, wherein rendering (S101) the first digital dental model (200-1) with the first material combination is performed by a first processor, and rendering (S103) the second digital dental model (200-2) with the second material combination is performed by a second processor.

4. The method according to any one of claims 1-3, wherein the first material combination and / or the second material combination comprises at least two different prosthesis materials.

5. The method according to any one of claims 1-3, wherein the spatial structure of the first digital dental model (200-1) and / or the second digital dental model (200-2) is predetermined.

6. The method according to any one of claims 1-3, wherein rendering is performed based on the color value, reflection value, transmission value, and / or absorption value of the corresponding prosthesis material.

7. The method according to any one of claims 1-3, wherein during rendering, the rendering also takes into account the optical properties of the viscous layer, composite layer, adhesive layer, and / or the color impression of the preparation.

8. The method according to any one of claims 1-3, wherein the specific quantity of the prosthesis material is predetermined, and the method is repeated for all possible material combinations.

9. The method according to claim 8, wherein the selected material combination for manufacturing is the material combination having the minimum deviation between the target data set DS-S and the corresponding actual data set.

10. The method according to any one of claims 1 - 3, wherein, The digital dental model has a predetermined external shape and a predetermined internal structure.

11. The method according to any one of claims 1-3, wherein the target data set DS-S is obtained based on a natural tooth.

12. The method according to claim 11, wherein the target data set DS-S represents the optical properties and / or geometry of the natural tooth.

13. A computer device for manufacturing a dental prosthesis (100), comprising a manufacturing device adapted to execute the method according to any one of claims 1-12.

14. A computer program product, comprising instructions for causing the computer device according to claim 13 to execute the method steps according to any one of claims 1-12.

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