Method for manufacturing a dental prosthesis

Abstract

To provide a method for manufacturing a dental prosthesis that determines the combination of materials for a dental prosthesis that is equivalent to the appearance of a required natural tooth.SOLUTION: A method for manufacturing a dental prosthesis comprises the steps of: rendering a first digital tooth model having the combination of first materials (S101); determining a first difference between the target dataset and the first actual dataset (S102); rendering a second digital tooth model on the basis of the combination of second materials for creating the second actual dataset that reproduces the optical characteristic of a second digital tooth model (S103); determining a second difference between the target dataset and the second actual dataset (S104); and manufacturing a dental prosthesis on the basis of the first digital tooth model when the first difference is smaller than the second difference, and manufacturing the dental prosthesis on the basis of the second digital tooth model when the second difference is smaller than the first difference (S105).SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Dental prostheses can be made from a number of different materials to replicate the appearance of natural teeth as closely as possible. However, selecting the right material can be complex and can produce less-than-optimal results. It is often unclear how the optical properties of a dental prosthesis are achieved by the prosthesis material. Therefore, it is difficult to manufacture a new dental prosthesis with the desired optical properties. Summary of the Invention [Problem to be solved by the invention]

[0003] The technical problem of the present invention is therefore to determine a combination of materials for a dental prosthesis that corresponds to the desired appearance of natural teeth. [Means for solving the problem]

[0004] The above technical problem is solved by the subject matter of the independent claims. Technically preferred embodiments are the subject matter of the dependent claims, the description and the accompanying drawings.

[0005] According to a first aspect, the aforementioned technical problem is solved by a method for manufacturing a dental prosthesis, comprising the steps of: rendering a first digital tooth model with a first raw material combination to create a first actual data set that replicates optical properties of a first digital tooth model; determining a first difference between a target data set and the first actual data set; rendering a second digital tooth model with a second raw material combination to create a second actual data set that replicates optical properties of a second digital tooth model; determining a second difference between the target data set and the second actual data set; manufacturing a dental prosthesis based on the first digital tooth model if the first difference is smaller than the second difference, and manufacturing a dental prosthesis based on the second digital tooth model if the second difference is smaller than the first difference.

[0006] According to this method, by varying the allocation of different prosthesis materials to the internal architecture of a tooth model for the dental prosthesis to be manufactured, the appearance of the resulting dental prosthesis can be calculated in advance. By comparing the optical appearance of each actual data set with a fixed target data set, the optimal result can be determined from among multiple combinations. The target data set can be predetermined based on the adjacent teeth. In this way, the combination and allocation of materials for manufacturing the dental prosthesis can be determined. In this case, the external shape and internal architecture of the dental prosthesis can be specified in advance.

[0007] According to a technically preferred embodiment of the method, the first digital tooth model and the second digital tooth model represent the same spatial geometry, which achieves technical advantages, e.g., that the method can be performed with greater accuracy.

[0008] According to another technically preferred 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, thereby achieving technical advantages such as the rendering steps being performed concurrently and thus allowing for faster execution of the method.

[0009] According to another technically preferred embodiment of the method, the rendering of the first digital tooth model is performed in parallel with the rendering of the second digital tooth model, thereby also achieving technical advantages, e.g., rendering steps can be performed concurrently and thus the method can be performed faster.

[0010] According to another technically preferred embodiment of the method, the first and / or second difference is calculated based on a Euclidean distance between the target data set and the actual data set or based on a spectral distance between the target data set and the actual data set, thereby achieving a technical advantage, for example, that the difference can be calculated with high accuracy.

[0011] According to another technically preferred embodiment of the method, the combination of the first and / or second material comprises at least two different prosthesis materials, thereby achieving technical advantages, for example, in that a dental prosthesis having as natural an appearance as possible is obtained.

[0012] According to another technically preferred embodiment of the method, the spatial structure of the first and / or second digital tooth model is preset, thereby achieving the technical advantage that, for example, the structure of the digital tooth model is kept constant and only the raw material combination is changed, thereby reducing the calculation time of the method.

[0013] According to another technically preferred embodiment of the method, the rendering is performed based on color values, reflection values, transmission values ​​and / or absorption values ​​of the corresponding prosthesis raw material, thereby achieving the technical advantage that, for example, a highly accurate rendering is performed and the appearance of the subsequent dental prosthesis is faithfully reproduced to its natural appearance.

[0014] According to another technically preferred embodiment of the method, the optical properties of the cement layer, the composite layer, the adhesive layer and / or the color impression of the preparation are additionally taken into account during rendering, thereby achieving, for example, a naturalistic appearance during rendering and achieving the technical advantage that consideration is given to both the materials for the subsequent fixing of the dental prosthesis and for the preparation.

[0015] According to another technically preferred embodiment of the method, a predetermined number of prosthesis raw materials are predefined and the method is repeated for all possible raw material combinations, whereby the rendering steps can be performed in parallel, thereby achieving technical advantages, for example, in that the dental prosthesis can be fitted as precisely as possible.

[0016] According to another technically preferred embodiment of the method, a raw material combination is selected for production that has the smallest difference between the target data set and the corresponding actual data set, thereby achieving technical advantages, for example, in that an optimal result is achieved with a given prosthesis raw material.

[0017] According to another technically preferred embodiment of the method, the digital tooth model has a predefined outer shape and a predefined inner structure, whereby technical advantages are achieved, e.g., improved calculation basis.

[0018] According to another technically preferred embodiment of the method, the target data set is acquired on the basis of natural teeth, thereby achieving the technical advantage that, for example, the dental prosthesis can be adapted to the natural teeth.

[0019] According to another technically preferred embodiment of the method, the target data set reproduces the optical properties and / or geometry of natural teeth, thereby achieving technical advantages, e.g., further improving the reproduction fidelity of the dental prosthesis.

[0020] According to a second aspect, the aforementioned technical problem is solved by a computerized device for manufacturing a dental prosthesis using a manufacturing device suitable for carrying out the method according to the first aspect, thereby achieving the same technical advantages as the method according to the first aspect.

[0021] According to a third aspect, the above-mentioned technical problem is solved by a computer program comprising instructions for operating a computer device according to the second aspect to perform the method steps according to the first aspect, thereby achieving the same technical advantages as the method according to the first aspect.

[0022] Various embodiments of the present invention are illustrated in the accompanying drawings and will be described in more detail in the following description. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram illustrating a digital tooth model. [Figure 2] FIG. 1 is an illustration showing a comparison between a target dataset and an actual dataset. [Figure 3] FIG. 10 is an illustration showing the calculation of the discrepancy between the target data set and the actual data set. [Figure 4] FIG. 1 is a block diagram of a method for manufacturing a dental prosthesis. DETAILED DESCRIPTION OF THE INVENTION

[0024] FIG. 1 shows digital tooth models 200-1 and 200-2 for a dental prosthesis 100. The digital tooth models 200-1 and 200-2 predefine the external shape and internal spatial structure of the future dental prosthesis 100. The external shape can be created in a CAD program. The internal spatial structure can be calculated or imported from a database, e.g., derived from the structure of a natural tooth or calculated from the external shape of the dental prosthesis 100 or a natural tooth. For a given external shape of the dental prosthesis 100, the tooth models 200-1 and 200-2 allow the internal layer structure to be determined, and specific prosthesis raw materials 201 and 203 with given optical material parameters can be assigned to each individual layer. The appearance of the same residual tooth 207 or the same preparation of the tooth to be treated is assumed for the tooth models.

[0025] The first tooth model 200-1 represents the dental prosthesis 100, which is formed, for example, from layers of different prosthesis materials 201-1, 201-2, and 201-3. The prosthesis material 201-1 is used for the outer layer, the prosthesis material 201-2 is used for the middle layer, and the prosthesis material 201-3 is used for the inner layer, which may be a bonding layer 209.

[0026] The second tooth model 200-2 also reproduces the same dental prosthesis 100 formed in layers from different prosthesis materials 203-1, 203-2, and 203-3. Of course, the prosthesis material 203-1 is used for the outer layers, the prosthesis material 203-2 is used for the central layer, and the prosthesis material 203-3 is used for the inner layer. Here again, the inner layer may be a bonding layer 209 containing a bonding agent 203-3. Therefore, the combination of materials for the first tooth model 200-1 is different from the combination of materials for the second tooth model 200-2.

[0027] The optical and physical properties, such as color values, dispersion values, reflection values, transmission values, and / or absorption values, of each assigned prosthesis material 201-1, . . . , 201-3, 203-1, . . . , 203-3 are known.

[0028] Rendering (light simulation method) using ray tracing allows for the calculation of the color and translucency of a dental prosthesis based on the previously created tooth model 200. In this way, the appearance and visual impression of a subsequent biomimetic dental prosthesis, such as a bridge, crown, partial bridge, inlay, onlay, or veneer, can be calculated from the tooth model 200.

[0029] The rendering is performed using a physically correct simulation of the interaction of light with the dental prosthesis 100 and the prosthesis materials used, where known optical parameters of the individual prosthesis materials are used to create a computer-aided appearance of the dental prosthesis 100.

[0030] Therefore, it is possible to additionally take into account existing natural tooth material, e.g., residual teeth, on which the dental prosthesis 100 is to be attached. During rendering, an optical impression of the resulting dental prosthesis 100 is calculated for a given internal structure and selected prosthesis material. For rendering, calculation of reflection, transmission, and absorption values ​​for at least three wavelengths in the visible range can be performed computer-assisted.

[0031] For the manufacturing method, a target data set is first determined. This can be obtained by optical measurement and evaluation of the adjacent teeth. For this purpose, an electronic camera or a 3D scanner can be used, which can measure the color values, reflection values, transmission values, and / or absorption values, as well as the spatial shape or image of the natural teeth. Based on this data, a dental prosthesis 100 with properties as identical as possible is designed, and a spatial tooth model 200 is designed.

[0032] The target data set then functions to compare the appearance of the rendered dental prosthesis 100 while varying the prosthesis material assigned to the internal architecture until the best approximation to the target data set is found.

[0033] Ideally, for comparison purposes, the dental prosthesis 100 is rendered from the same viewing angle or perspective as when the target data set based on natural teeth was acquired. To improve the results, renderings can also be performed from different viewing angles. Renderings can be performed for any and all viewing angles and any selectable ambient conditions, such as a given lighting environment, taking into account the shape and optical properties of neighboring teeth, the position of the dental prosthesis 100 in the oral cavity, or the remaining teeth to be created. The rendering can also take into account other influencing factors, such as known optical data of the bonding layer 209 (cement, composite, and / or adhesive).

[0034] Thus, rendering the digital tooth models 200-1 and 200-2 provides a real data set that reproduces the optical properties of the digital tooth models 200-1 and 200-2.

[0035] Figure 2 shows the difference ΔE between the target dataset and the actual dataset DS-I (DS-I-1, DS-I-2). S,I The target data set DS-S is acquired by, for example, an electronic camera 101.

[0036] The digitally generated tooth model 200 contains data about the spatial geometry of the dental prosthesis 100, the prosthesis materials assigned to form the dental prosthesis 100, and the areas where those prosthesis materials are placed. The optical and physical properties of the prosthesis materials required for rendering are known in the rendering software and can be retrieved from a parameter table to which new materials are constantly added.

[0037] The actual data set DS-I is obtained by performing a rendering of the digital tooth model 200 with the selected material combination, taking into account the spatial geometry of the dental prosthesis 100 and the optical and physical properties of the various prosthesis materials that may be present, including bonding materials and residual teeth or preparations, if necessary.

[0038] The propagation of light within the tooth model 200 can be described by Maxwell's equations. The rendering uses, for example, the radiative transfer equation (RTE), whereby the propagation medium is described by an absorption coefficient, a scattering coefficient, a refractive index, and a scattering phase function.

[0039] The digital tooth model 200 contains data regarding the spatial geometry and internal architecture of the dental prosthesis 100, as well as the absorption coefficients, scattering coefficients, refractive indices, and scattering phase functions of each of the prosthesis materials 201 and 203 of the architecture. The scattering phase function can be numerically solved to any required accuracy by Monte Carlo simulation (ray tracing) using the above-mentioned parameters during rendering based on the tooth model 200, in which a large number of photons propagate on random paths through the tooth model 200.

[0040] As a result, a real data set DS-I for the appearance of the dental prosthesis 100 can be calculated by rendering, taking into account the raw materials used and the external and internal architecture of the tooth model 200. This calculated real data set DS-I can then be compared with a target data set DS-S obtained on the basis of the adjacent teeth. To simplify the comparison, it can be performed on two-dimensional derivatives (two-dimensional images). However, three-dimensional methods can also generally be used. The difference ΔE between the real data set DS-I and the target data set DS-S S,I A numerical value is calculated as a measure of

[0041] Figure 3 shows the difference ΔE between the target dataset DS-S and the real dataset DS-I. S,IThe calculation of is shown schematically. For example, dataset DS-S contains a representation of a tooth in a given projection, whereas dataset DS-I rendered from tooth model 200 contains a representation of tooth model 200 in the same projection. Images from both target dataset DS-S and actual dataset DS-I are scaled to the same size and placed side by side.

[0042] The Euclidean difference ΔE between the target data set DS-S and the real data set DS-I S,I (ΔE1 S,I ,ΔE2 S,I ) represents the difference in color values ​​of pixels along the comparison line 205, e.g., Lab(L * a * b * ) color space, by accumulating. The comparison line 205 can be arbitrarily shifted by simultaneously moving each half of the tooth. However, in general, the comparison line 205 can have other trajectories. The comparison can be performed at the pixel level as a minimum resolution.

[0043]

number

[0044] The greater the difference in color change along the comparison line 205, the greater the numerical difference ΔE S,I When the target data set DS-S and the actual data set DS-I are perfectly color matched, the difference ΔE S,I However, in general, other methods, such as those based on spectral information, can be used to calculate the difference ΔE S,I It can also be used to calculate

[0045] 4 shows a block diagram of a method for manufacturing the dental prosthesis 100. In a first step S101, a first digital tooth model 200-1 having a first raw material combination is rendered to create a first actual data set DS-I-1 that reproduces the optical properties of the first digital tooth model 200-1. In step S102, a first difference ΔE1 between the target data set DS-S and the first actual data set DS-I-1 is calculated. S,I The first actual data set DS-I-1 is compared with the target data set DS-S to obtain

[0046] Then, in step S103, the second digital tooth model 200-2 is rendered with a second raw material combination to create a second actual data set DS-I-2 that replicates the optical properties of the second digital tooth model 200-2. In step S104, a second difference ΔE2 between the target data set DS-S and the second actual data set DS-I-2 is calculated. S,I Similarly, the second actual data set DS-I-2 is compared with the target data set DS-S to obtain

[0047] In step S105, the first difference ΔE1 S,I is the second difference ΔE2 S,I Manufacture the dental prosthesis 100 based on the first digital tooth model 200-1 if the second difference ΔE2 S,I is the first difference ΔE1 S,I If it is smaller, the dental prosthesis 100 is manufactured based on the second digital tooth model 200-2.

[0048] This method allows rendering of all possible material combinations for a given geometrical shape of the entire system. By calculating all possible material combinations, it is possible to find the best combination that best approximates the target data set DS-S and best mimics the appearance of natural teeth, for example. This method performs an objective target-actual comparison and achieves a computer-assisted optimal allocation (best match) of prosthetic materials to the corresponding spatial regions of the dental prosthesis 100.

[0049] Therefore, the internal structure of the tooth models 200-1 and 200-2 remains the same, and the variations in the combination of selected raw materials are calculated for each layer, after which the best combination is found.

[0050] The rendering of the digital tooth models 200-1 and 200-2 can be performed in parallel or simultaneously on different processors, thereby achieving optimal results in a short time. By rendering different possible material allocation patterns in parallel, a rapid detection of an optically patient-specific dental prosthesis 100 is achieved, eliminating the need for repetitive calculations.

[0051] Parallel calculation and simulation of all possible material combinations for a tooth model 200 with a given external shape and internal architecture, followed by comparison of the resulting actual and target data sets, can be used to find the optimal material combination.

[0052] Additionally, within this method, it is also possible to calculate tooth models 200-1 and 200-2 with virtual prosthesis raw materials that have previously been assigned given optical properties. From this, it is also possible to find a suitable raw material combination. After that, the dental prosthesis 100 can be manufactured using real prosthesis raw materials with properties similar to those of the virtual prosthesis raw materials 201 and 203. In this way, the desired overall impression of the prosthesis 100 can be achieved.

[0053] This method allows the optimal selection and allocation of prosthetic materials 201 and 203 for producing a multi-layered prosthesis 100 to be determined prior to fabrication of the prosthesis 100, while simultaneously establishing optimal aesthetics for the prosthesis 100. By rendering with the physical and optical parameters of the actual prosthetic materials, the dental prosthesis 100 can then be manufactured with the optimal material combination.

[0054] Once the material combination is determined, the dental prosthesis 100 can be manufactured using the corresponding prosthesis material combination by 3D printing or other suitable method. A computer system can be used to perform the calculation steps and then manufacture the dental prosthesis 100 using a manufacturing device. To this end, the computer system executes a computer program containing instructions that operate to cause the computer system to perform the necessary method steps. The computer system includes a processor and digital memory, and the digital memory stores data sets and a computer program that executes the method steps and appropriately controls the manufacturing device. The manufacturing device can be, for example, a 3D printer that prints the dental prosthesis 100 using various prosthesis materials. However, other manufacturing devices that are generally capable of manufacturing dental prostheses using various prosthesis materials can also be used.

[0055] All of the features described and illustrated in relation to individual embodiments of the invention can also be the subject of the invention in various combinations, whereby simultaneous advantageous results are achieved.

[0056] All method steps may be performed using apparatus suitable for performing each method step. All functions performed by the feature of interest may be method steps in this method.

[0057] The scope of protection of the present invention is defined by the appended claims and is not limited by the features described or shown in the description. [Explanation of symbols]

[0058] 100 Dental Prostheses 101 Electronic Camera 200 tooth model 201 Prosthetic materials 203 Prosthetic Materials 205 Comparison Line 207 Remaining teeth 209 Connecting layer DS-I real dataset DS-S target dataset

Claims

1. Rendering a first digital tooth model (200-1) having a first raw material combination to create a first real data set (DS-I-1) that reproduces the optical properties of the first digital tooth model (200-1) (S101); The first difference (ΔE1 Ｓ，Ｉ ) is determined (S102), Rendering the second digital tooth model (200-2) with the second raw material combination to create a second real data set (DS-I-2) that replicates the optical properties of the second digital tooth model (200-2) (S103); Rendering (S101) of a first digital tooth model (200-1) having a first raw material combination, where the first digital tooth model (200-1) and the second digital tooth model (200-2) reproduce the same spatial geometry, is performed by a first processor, rendering (S103) of a second digital tooth model (200-2) having a second raw material combination, is performed by a second processor, and a second difference (ΔE2 Ｓ，Ｉ ) is determined (S104), The first difference (ΔE Ｓ，Ｉ ) is the second difference (ΔE2 Ｓ，Ｉ ), and manufacturing a dental prosthesis (100) based on the first digital tooth model (200-1) when the second difference (ΔE2 Ｓ，Ｉ ) is the first difference (ΔE1 Ｓ，Ｉ ), manufacturing (S105) a dental prosthesis (100) based on the second digital tooth model (200-2), if the difference between the target data set (DS-S) and each actual data set is smaller than the predetermined number of prosthesis raw materials defined in advance, and this method is repeated for all possible combinations of raw materials to select for manufacturing a combination of raw materials that has the smallest difference between the target data set (DS-S) and each actual data set.

2. The first and / or second difference (ΔE Ｓ，Ｉ , ΔE2 Ｓ，Ｉ 2. The method of claim 1, wherein the DS-S is calculated based on the Euclidean distance between the target data set (DS-S) and the actual data set (DS-I), or based on the spectral distance between the target data set (DS-S) and the actual data set (DS-I).

3. 3. The method according to claim 1 or 2, wherein the combination of first and / or second materials comprises at least two different prosthetic materials (201-1, ..., 201-3, 203-1, ..., 203-3).

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

5. A method according to any one of claims 1 to 4, wherein rendering (S101, S103) is performed based on the color values, reflectance values, transmittance values, and / or absorption values ​​of each prosthetic material.

6. 6. The method according to claim 1, further comprising taking into account the optical properties of the cement layer, the composite layer, the adhesive layer and / or the color impression of the preparation during rendering (S101, S103).

7. A method according to any one of claims 1 to 6, wherein the digital tooth model has a predefined outer shape and a predefined internal structure.

8. A method described in any one of claims 1 to 7, wherein the target data set (DS-S) is obtained based on natural teeth.

9. The method of claim 8, wherein the target data set (DS-S) reproduces the optical properties and / or geometry of a natural tooth.

10. A computerized apparatus for manufacturing a dental prosthesis (100) using a manufacturing device suitable for carrying out the method according to any one of claims 1 to 9.

11. A computer program comprising instructions for operating a computer device according to claim 10 to perform the method steps of any one of claims 1 to 9.

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