3D Printed Mouthpiece with Deformation Simulation

Abstract

In particular, a method for manufacturing a mouthpiece by ejecting droplets of a first droplet material and a second droplet material in a 3D printing process is disclosed. The method includes the steps of obtaining dental data of a user and an input mouthpiece model. A simulation is performed to determine the deformation of the input mouthpiece model in response to an applied force. Based on this deformation, the input mouthpiece model is adapted to a working mouthpiece model by replacing at least part of the material of the input mouthpiece model with a replacement material. Finally, a mouthpiece is manufactured based on the optimized working mouthpiece model.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a mouthpiece. In particular, it relates to a method of manufacturing by the layer-by-layer deposition of individual droplets from an ejection head, and more particularly, by ejecting droplets of a first droplet material and a second droplet material. This method includes steps of obtaining dental data of a user including a 3D dental model of a virtual upper jaw and / or a virtual lower jaw similar to the upper jaw and / or the lower jaw of the user's oral cavity, obtaining an input mouthpiece model, performing a simulation in which the input mouthpiece model is placed on at least one of the virtual upper jaw and the virtual lower jaw, adapting the input mouthpiece model to a working mouthpiece model, and manufacturing a mouthpiece based on the working mouthpiece model.

Background Art

[0002] US10188485B2 discloses a dental appliance that can protect teeth from clenching and grinding. This dental appliance includes a cover frame having tooth recesses formed in the longitudinal direction. The cover frame has a layer structure including a first cover layer made of a hard material and a second cover layer made of a soft material provided inside the first cover layer. A core frame made of a hard material is provided in the tooth recess, and it has a tooth contact surface with a shape in which the ends of a plurality of teeth are engraved.

[0003] This dental appliance has a configuration excellent in durability and wearing comfort. Thereby, teeth can be protected from strong biting force during clenching or grinding. This dental appliance includes a mouthpiece that can be worn on teeth to protect the teeth from external impacts applied to the face by a punch or a ball during practice of combat sports or ball games. This mouthpiece can be customized for personal use.

[0004] W02012 / 140021 discloses a method for manufacturing an orthodontic appliance in a customized manner including a step of simulation.

[0005] This orthodontic appliance can have multiple embodiments. In some embodiments, the orthodontic appliance is selected from the group consisting of braces, brackets, sprints, fixed appliances, archwires, aligners, and shells. In some embodiments, the virtual orthodontic appliance is configured such that the manufactured orthodontic appliance does not interfere with the patient's tooth clenching. In some embodiments, the virtual orthodontic appliance is configured such that the manufactured orthodontic appliance can be comfortably worn by the patient. In some embodiments, the effect of the orthodontic appliance is to provide a set of tooth protection, such as when the orthodontic appliance includes a mouthguard. The orthodontic appliance may include a tooth protection device.

[0006] In this method, a virtual orthodontic appliance is generated that includes a first portion configured to be disposed in a first section of a virtual 3D tooth model of the patient's teeth. The virtual 3D tooth model includes a virtual upper jaw and a virtual lower jaw that are respectively similar to the patient's upper and lower jaws of the mouth. In this method, an initial shape of the virtual orthodontic appliance is provided. The initial virtual orthodontic appliance can be provided by selecting from a pre-defined set of virtual orthodontic appliances in a library. A target virtual dynamic occlusion for a set of teeth is determined. Virtual dynamic occlusion is performed using the virtual orthodontic appliance disposed in anatomically correct positions in the 3D model, and the virtual orthodontic appliance is adjusted based on the results of the virtual dynamic occlusion.

[0007] In some embodiments, the method includes defining a target contact distribution between a portion of a virtual orthodontic appliance and a section of a virtual 3D tooth model. When an orthodontic appliance manufactured from the virtual orthodontic appliance is placed on a patient's teeth, the portion of the orthodontic appliance corresponding to the target contact distribution contacts the patient's teeth. An effect threshold may be related to the measurement of the contact distribution on one or more surfaces of the teeth, such as the occlusal surfaces of the teeth during occlusion, if the orthodontic appliance is manufactured from the current form of the virtual model. The effect threshold may include a two-dimensional mapping of the contact distribution on all of these occlusal surfaces or selected teeth in a first section of the virtual 3D tooth model. The virtual orthodontic appliance may be adjusted, for example, if the results of a virtual dynamic occlusion indicate that the current contact distribution differs from the target contact distribution by more than a contact threshold.

[0008] In some embodiments, the effect of an orthodontic appliance on a patient is estimated from the distribution of impact points measured using virtual dynamic occlusion. Impact points may appear, for example, at the collision between a portion of the virtual orthodontic appliance and a section of the virtual 3D tooth model. In some embodiments, the method includes adjusting the virtual orthodontic appliance based on the estimated effect of the orthodontic appliance.

[0009] The orthodontic appliance may be manufactured from the virtual orthodontic appliance using different techniques. This technique may include the forming of metal parts such as wax and casting, 3D printing, milling, cables and plates. This technique may be implemented alone or in combination. The manufacture of the orthodontic appliance may include a two-material process in which different parts of the orthodontic appliance are manufactured from different materials.

[0010] In some embodiments, the properties of the material(s) used in the manufacture of the orthodontic appliance are considered when generating the virtual orthodontic appliance. Material properties may be included in the generation of the virtual orthodontic appliance. By using a flexible material on the tooth contact surface of the manufactured orthodontic appliance, some undercuts at the bottom of the teeth may be tolerated. Thereby, for example, the retainer can be more securely fixed to the patient's teeth.

[0011] In some embodiments, the virtual orthodontic appliance is adjusted by an additive process or a subtractive process in which material is virtually added to or removed from the virtual orthodontic appliance, such as being virtually added to or removed from the modified surface of the first and / or second portion of the virtual orthodontic appliance.

[0012] A drawback of this method for manufacturing an orthodontic appliance is that the final product of the manufactured mouthpiece may have poor quality. In particular, it is desirable to obtain an appropriate method for adapting the input mouthpiece model to the working mouthpiece model in order to improve the quality of the manufactured mouthpiece.

[0013] It should be noted that any discussion of the documents, acts, materials, devices, articles, etc. included in this specification with respect to the above prior art is for the purpose of providing the context of the present invention, and it is not to be recognized that such matters constitute a part of the prior art or are common general knowledge in the technical field related to the present invention prior to the priority date of each claim of this application.

Summary of the Invention

[0014] A general object of the present invention is to at least partially remove the above drawbacks and / or provide a usable alternative. More specifically, an object of the present invention is to provide a method for manufacturing a mouthpiece based on an improved working mouthpiece model.

[0015] According to the present invention, this object is achieved by the method for manufacturing a mouthpiece according to claim 1. In particular, this method is configured to manufacture a mouthpiece by 3D printing. More specifically, the mouthpiece is manufactured by the laminated deposition of individual droplets from an ejection head, more specifically, by ejecting droplets of at least a first droplet material and a second droplet material that are different from each other, thereby making it possible to manufacture a mouthpiece from a combination of soft and hard materials.

[0016] In the steps of this method, the dental data of the user is acquired. The dental data enables the manufacture of a customized mouthpiece. The dental data includes 3D tooth models of a virtual upper jaw and / or a virtual lower jaw that are similar to the user's upper and / or lower jaws. The dental data may be acquired in several ways, for example, by scanning the oral cavity using a scanning device. Intraoral scanners for obtaining an individual's oral information are widely known.

[0017] In the steps of this method, an input mouthpiece model is obtained. The input mouthpiece model may be obtained from a library file that defines the preset shape of the mouthpiece to be manufactured. The input mouthpiece model may represent any type of mouthpiece, for example, an occlusal splint or a mandibular advancement device including upper and lower splints. The mouthpiece to be manufactured may be configured to cover only the teeth of the lower or upper jaw or a part of the user's teeth. The mouthpiece may be provided as a mouthguard for any type of purpose, for example, for tooth repositioning, for treating teeth grinding, or for protection during sports activities.

[0018] In the steps of this method, a simulation is performed in which the input mouthpiece model is placed on at least one of the virtual upper jaw and / or the virtual lower jaw. In this simulation, the deformation of the input mouthpiece model in response to the applied force is determined. The applied force may be a biting force or an external impact force, for example, a force generated by teeth grinding or a force generated in combat sports.

[0019] Specifically, in this method, the biting force is simulated to obtain the deformation of the input mouthpiece model. The input of the biting force obtained by this method may be a standardized biting force recognized in the literature for a specific group of users or a specific treatment. Preferably, the input of the biting force in the simulation is individualized for a specific user. The input of the biting force includes measured data and may be uploaded as the input of the biting force to perform the simulation for individual users.

[0020] The deformation of the input mouse piece model provides information regarding the stress that occurs at specific locations of the mouse piece. This deformation provides information on how the input mouse piece model should be adapted to the working mouse piece model, which forms the basis for 3D printing the mouse piece. Preferably, the simulated deformation of the mouse piece is presented to the operator by means of a color map. The different colors within the map visualize where possible adaptations of the input mouse piece model are desirable. The operator may inspect the presented deformation and determine how to adapt the input mouse piece model in order to obtain an appropriate working mouse piece model. In one embodiment, the method may include control electronics programmed to adapt the input mouse piece model based on the determined deformation. Based on software rules, the input mouse piece model may be adapted and possibly re-simulated to obtain a working mouse piece model that provides an acceptable deformation when the mouse piece is subjected to the applied forces.

[0021] In a step of this method, the input mouse piece model is adapted to the working mouse piece model by replacing at least a portion of the material of the input mouse piece model with a replacement material. After performing at least one adaptation, based on the working mouse piece model, the mouse piece can be manufactured, particularly by 3D printing.

[0022] The method according to the invention is beneficial in that the simulation of the deformation of the mouse piece as a result of the forces applied during use can timely reveal undesirable deformations of the mouse piece. Small local plastic deformations are such undesirable deformations. Undesirable deformations can affect the wearing feeling of the mouse piece. In more severe cases, the simulated deformation of the mouse piece can become so large that the mouse piece loses its function during use. In extreme situations, the deformation may even cause local cracks in the mouse piece.

[0023] By performing a simulation, undesirable deformations are detected at an early stage before actually manufacturing the mouthpiece. If unacceptable deformations are revealed by the simulation, the input mouthpiece model is adapted by locally replacing the material with a replacement material in order to reduce or increase the occurring deformations. The replacement material replaces the previously defined material within the input mouthpiece model, which locally hardens or softens the mouthpiece to change the occurring deformations to an acceptable ratio.

[0024] Preferably, the step of simulating the deformation and adaptation of the input mouthpiece model is repeatedly performed until a final working mouthpiece model that serves as a basis for 3D printing the mouthpiece is obtained. In a preferred iterative process, the simulation is performed multiple times on the modified input mouthpiece model containing the replacement material in order to evaluate the modified deformation.

[0025] Preferably, the input mouthpiece model is initially composed of a single material. Before performing the first simulation, the input mouthpiece model, i.e., the basic input mouthpiece model, contains a single material, particularly a soft printing material. The simulation starts with the input mouthpiece model of a single material. Preferably, the single material of the input mouthpiece model is softer than the replacement material. After the steps of simulation and adaptation, the input mouthpiece model is adapted and locally contains at least one part of the replacement material.

[0026] In one embodiment of the method according to the invention, the replacement material has a composition containing only a hard printing material. The hard printing material may be configured to replace the material part of the input mouthpiece model that undergoes the maximum deformation. The operator may specify the area or volume of the replacement material and the material to be replaced. In the part of the maximum deformation, the highest stress occurs. By replacing with a hard material, the amount of deformation is reduced. Thereby, the conformity and functionality of the mouthpiece to the upper or lower jaw can be improved. Tooth protection can be improved and tooth grinding can be prevented.

[0027] Soft or hard materials for 3D printing are typically defined by a given bending strength. Typically, soft printing materials have a bending strength in the range of at least 1.0 MPa to a maximum of 10 MPa, particularly substantially about 2.0 MPa. Typically, hard materials have a bending strength in the range of at least 60 MPa, particularly at least 80 MPa.

[0028] In one embodiment of the method according to the invention, the replacement material may be a mixture of a hard printing material and a soft printing material. The replacement material may be a mixture of a plurality of printing materials having at least a certain amount of hard printing material and a certain amount of soft printing material. The replacement material has a certain mixing ratio of the hard printing material and the soft printing material. The mixture is suitable for replacing a part of the material that undergoes an intermediate value of stress. The intermediate value of stress is between the maximum and minimum stresses corresponding to the simulated maximum and minimum deformations.

[0029] In one embodiment of the method according to the invention, the mixing ratio of the mixture of the hard printing material and the soft printing material for predicting the simulated deformation may be determined by an empirical process. For the printing process, the mixing ratio may be established so as to be applicable when a specific deformation is determined in the simulation step. Thereby, the mixing ratio of the mixture may be defined so as to appropriately predict the occurring deformation.

[0030] In one embodiment of the method according to the present invention, the mixing ratio of the mixture of the hard printing material and the soft printing material is proportional to a specific deformation. In this method, a linear dependence is assumed between the simulated deformation and the mixing ratio of the replacement material for compatibility. Preferably, the volume ratio of the mixture is linearly related to the degree of deformation. For compatibility, the mixture may not include the hard material for the part with the minimum deformation and may not include the soft material for the part with the maximum deformation. The mixture includes a proportional amount of the hard and soft printing materials for the deformation between the minimum and maximum deformations. Preferably, the mouthpiece is manufactured by a 3D printer including an ejection head for ejecting droplets of the first droplet material and the second droplet material. Preferably, one of the first and second droplet materials defines the hard material, and the other of the first and second droplet materials defines the soft material.

[0031] In one embodiment of the method according to the present invention, the simulated deformation is divided into at least three ranges, for example, including the ranges of high, low, and intermediate deformations.

[0032] Preferably, the input mouthpiece model is meshed. The meshed input mouthpiece model may be divided into slices, and each slice includes a matrix of pixels.

[0033] In one embodiment of the method according to the present invention, the method has a step of specifying a replacement material for the surface voxels and a step of specifying a replacement material for the internal voxels. Preferably, in the steps of the method, local deformation is first determined at the surface voxels of the input mouthpiece model, particularly at the tooth contact surface, to simulate the deformation at the contact surface before determining the deformation in the internal voxels.

[0034] In one embodiment of the method according to the invention, the simulation provides only the deformation in the surface voxels. Based on the surface deformation, the material properties of the part with a specific depth may be defined. In the adaptation software, an algorithm for defining the internal material properties based on the surface deformation may be defined. To define the internal material properties, at least two input parameters may be used, and the at least two input parameters include the penetration depth and the gradient of the transition between materials.

[0035] In an embodiment of the method according to the invention, the deformation of the input mouthpiece model is defined by the deformation model. In one step, at least one deformed part is assigned. The position of the deformed part with a specific deformation, for example low, high, or intermediate deformation, is determined. Preferably, a partial depth is additionally defined for the specific deformed part to define the volume of the deformed part to be adapted. The deformed part is at least partially replaced by a replacement material corresponding to the determined amount of deformation in this step of the method. Preferably, the input mouthpiece model is divided into slices, where, in particular, after the simulation, the droplet material is defined in the working mouthpiece model within a separate bitmap for the specific slice. Furthermore, the invention relates to a 3D printer comprising a control electronic device programmed to execute the method according to the invention.

[0036] Furthermore, the invention relates to a computer program product comprising a computer-readable medium having computer-readable code embodied therein, the computer-readable code being configured such that when executed by a suitable computer or processor, the computer or processor is caused to execute the method according to the invention.

[0037] Furthermore, the invention relates to a mouthpiece obtained by the method according to the invention.

[0038] In one embodiment of the mouthpiece according to the present invention, the mouthpiece has a local patch of replacement material. This local patch is configured to compensate for unacceptable deformations. The local patch is defined by the volume of at least one voxel. In particular, the local patch is up to 0.3 cm 3 , in particular up to 0.1 cm 3 in volume.

[0039] In one embodiment of the mouthpiece according to the present invention, the local patch is placed at a customer-specific location in order to obtain a customized mouthpiece. The use of the method according to the present invention is particularly beneficial for customizing user-specific mouthpieces such as an individual's missing teeth. By compensating for these user specificities, a mouthpiece is provided that has at least one local patch of replacement material at at least one customer-specific location.

[0040] In one embodiment of the mouthpiece according to the present invention, the local patch of replacement material is placed under the surface layer of the mouthpiece. Next, the local patch is fully embedded in the mouthpiece. The local patch is applied at a specific depth within the mouthpiece, for example a depth of 3 mm. Here, the local patch functions to compensate for otherwise unacceptable deformations.

Brief Description of the Drawings

[0041] The present invention will be described in more detail with reference to the accompanying drawings. The drawings illustrate actual embodiments according to the present invention and should not be construed as limiting the scope of the present invention. Specific features may be considered separately from the illustrated embodiments and may be considered in a broader context as features common to all embodiments within the scope of the appended claims as well as the illustrated embodiments.

Figure 1

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Figure 5

Mode for Carrying Out the Invention

[0042] Figure 1 shows a graphical representation of an embodiment of a method according to the present invention for manufacturing a mouthpiece.

[0043] In the first step of this method, dental data is acquired. The dental data of the user includes a 3D tooth model of the virtual upper jaw and / or virtual lower jaw. The dental data may be acquired by a scanning process using a scanning tool.

[0044] In one step of the method, an input mouthpiece model is obtained. The input mouthpiece model is preferably obtained from a library. Preferably, the input mouthpiece model is defined by a single material.

[0045] In the first step of this method, a simulation is performed. In the simulation, the input mouthpiece model is placed on at least one of the virtual upper jaw and the virtual lower jaw. The input mouthpiece model may represent, for example, a night guard mouthpiece worn on the user's upper jaw. In the simulation, a virtual articulator can be used to determine the deformation of the input mouthpiece model in response to the applied force. Preferably, such a simulated applied force represents the biting force of an individual user. Thereby, a deformation model is obtained.

[0046] An example of such a deformation model 2 is shown in FIG. 2. The deformation model is shown as a color map. Here, different colors are indicated by hatching. Each color represents a specific deformation 21, 22, 23 at a specific position of the input mouthpiece model 20. The color map of the deformation model visualizes for the operator the positions where the input mouthpiece model may need to be adapted in order to obtain a suitable working mouthpiece model that can be used for the manufacture of the mouthpiece. In a more advanced way of performing this method, the control electronics may be programmed to adapt the input mouthpiece model based on predetermined programmed rules. The control electronics may include an algorithm for adapting the input mouthpiece model that presents specific deformations in response to the applied force. Here in FIG. 2, the color map of the deformation model 2 shows the portions that undergo high deformation 23, low deformation 21, and intermediate deformation 22. First, the input mouthpiece model may be composed of a single material. The initially obtained deformation model 2 may show the portions of the input mouthpiece model that are replaced by the replacement material in the first step of adaptation. Preferably, the steps of simulation and adaptation of the input mouthpiece model are repeatedly executed until a final working mouthpiece model is obtained that serves as a basis for manufacturing the mouthpiece.

[0047] In a step of this method, a working mouthpiece model 3 is obtained. The working mouthpiece model 3 may be visualized with simulation software. FIGS. 3 and 4 show an example of such a working mouthpiece model 3, which here is similar to an occlusal splint. FIG. 4 is a cross-sectional view along the arrow in FIG. 3. The working mouthpiece model has a tooth contact surface 31, an inner side surface 32, an outer side surface 32, and an occlusal surface 33. The tooth contact surface refers to a part of the occlusal splint that faces one or more teeth of the user during use. Here, the tooth contact surface includes both a soft material and a hard material, and the occlusal surface includes only the hard material.

[0048] The portion of the deformation model determined to undergo intermediate deformation may be defined in the working mouthpiece model by the volume of material providing intermediate hardness. The mouthpiece is preferably manufactured by 3D printing, more preferably by the layer-by-layer deposition of individual droplets from an ejection head. In particular, the method for manufacturing a mouthpiece according to the present invention can manufacture a mouthpiece by a 3D printing process in which droplets of a plurality of materials or droplets of different materials are ejected from an ejection head.

[0049] Preferably, in the printing process, a first droplet material and a second droplet material are ejected. The first droplet material and the second droplet material can be combined in the printing process to obtain a volume of material corresponding to the volume of material in the working mouthpiece model. One of the first and second droplet materials is defined as a soft material and the other is defined as a hard material.

[0050] The different droplet materials may be specified for different physical properties. The first droplet material may be selected with respect to a predetermined elasticity defined by, for example, Young's modulus, and the second droplet material may be selected with respect to another elasticity defined by a different Young's modulus. The volume of material may include a certain amount of droplets including the first and second droplet materials that result in an intermediate elasticity defined by the included droplets of the first and second materials. As shown in FIG. 5, in this method, an assumption that the simulated deformation of the input mouthpiece model is proportional to the elasticity of a certain volume of material may be incorporated into the method. This assumption may be incorporated into the control electronics of a 3D printer for performing the method. The maximum deformation corresponds to a volume of material consisting entirely of the soft droplet material, and the minimum deformation corresponds to a volume of material consisting entirely of the hard droplet material. The intermediate deformation corresponds to the ratio of the first and second droplet materials.

[0051] Having described the present invention in detail, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention as claimed below. All such changes and modifications are intended to be included within the scope of this disclosure and the claims.

[0052] Furthermore, it should be noted that any features of the method according to the invention described in the embodiments and / or in the dependent claims are considered to be patentable per se without depending on the other features presented. In particular, any means presented in the dependent claims are also considered to be patentable without depending on the independent claims.

[0053] Accordingly, the present invention provides, in particular, a method and a 3D printer for carrying out a method for manufacturing a mouthpiece by ejecting droplets of a first droplet material and a second droplet material in a 3D printing process. The method includes the steps of obtaining dental data of a user and an input mouthpiece model. A simulation is performed to determine the deformation of the input mouthpiece model in response to an applied force. Based on this deformation, the input mouthpiece model is adapted to a working mouthpiece model by replacing at least a part of the material of the input mouthpiece model with a replacement material. Finally, a mouthpiece is manufactured based on the optimized working mouthpiece model.

Claims

1. A method for manufacturing a mouthpiece, in particular by the layer-by-layer deposition of individual droplets from an injection head, more particularly by injecting droplets of a first droplet material and a second droplet material, the method comprising: obtaining dental data of the user including a 3D dental model of a virtual upper jaw and / or a virtual lower jaw similar to the upper jaw and / or the lower jaw of the user's oral cavity; obtaining an input mouthpiece model defining a preset shape of the mouthpiece to be manufactured; performing a simulation in which the input mouthpiece model is placed on at least one of the virtual upper jaw and the virtual lower jaw, and determining the deformation of the input mouthpiece model in response to an applied force; adapting the input mouthpiece model to a working mouthpiece model by replacing at least a part of the material of the input mouthpiece model with a replacement material; and manufacturing the mouthpiece based on the working mouthpiece model, in particular by 3D printing. A method comprising the above.

2. The method according to claim 1, wherein the steps of simulating the deformation and adapting the input mouthpiece model are repeatedly performed until a final working mouthpiece model serving as a basis for manufacturing the mouthpiece is obtained.

3. The method according to claim 1 or 2, wherein the input mouthpiece model is initially defined by a single material, in particular a material softer than the replacement material.

4. The method according to any one of claims 1 to 3, wherein the material of the input mouthpiece model is defined by a soft printing material having a predetermined bending strength, in particular in the range of at least 1.0 MPa to a maximum of 10 MPa, particularly substantially about 2.0 MPa, at an initial stage before the first simulation.

5. The method according to any one of claims 1 to 3, wherein the composition of the replacement material comprises only a hard printing material having a predetermined bending strength, in particular at least 60 MPa, more particularly 80 MPa.

6. The method according to any one of claims 1 to 5, wherein the replacement material is a mixture having at least a certain amount of hard printing material and a certain amount of soft printing material.

7. The amount of the hard material in the mixture of the replacement material is a predetermined deformation ε between a determined minimum deformation ε ｍｉｎ and a determined maximum deformation ε ｍａｘ and is proportional to the predetermined deformation ε ｘ between them. The composition does not contain hard material in the portion of the minimum deformation ε ｍｉｎ and does not contain soft material in the portion of the maximum deformation ε ｍａｘ The method according to claim 6.

8. The deformation ε of the mouthpiece is simulated by applying a biting force, and in particular, the biting force is individualized for a specific user so as to obtain a customized mouthpiece, according to the method of any one of claims 1 to 7.

9. A method according to any one of claims 1 to 8, comprising the step of specifying a replacement material for a surface voxel and the step of specifying a replacement material for an internal voxel.

10. The method according to claim 9, wherein a replacement material is specified for the surface voxel before a replacement material is specified for the internal voxel.

11. The method according to claim 9 or 10, wherein in the simulation step, only surface deformation is determined, and then, based on the obtained surface deformation, a replacement material for the internal voxel is determined.

12. The method according to any one of claims 1 to 11, wherein the simulated deformation of the input mouthpiece model is defined by a deformation model to which at least one deformed part is assigned.

13. The depth of the deformed part is determined, and in particular, the input mouthpiece model is divided into slices, and in particular, after performing the simulation, in a different bitmap for a specific slice, the droplet material in the working mouthpiece model is defined, according to the method of claim 12.

14. A mouthpiece obtained by the method according to any one of claims 1 to 13.

15. The mouthpiece has a local patch of replacement material configured to compensate for unacceptable deformation, and in particular, the local patch has a maximum of 0.3 cm ３ , in particular a maximum of 0.1 cm ３ in volume, the mouthpiece according to claim 14.

16. The mouthpiece according to claim 15, wherein the local patch of the replacement material is arranged at a customer-specific position in order to obtain a customized mouthpiece.

17. The mouthpiece according to claim 16, wherein the local patch is arranged at the position of a missing tooth of a specific customer.

18. The mouthpiece according to claim 16 or 17, wherein the local patch of the replacement material is arranged under the surface layer of the mouthpiece.

19. A 3D printer comprising a control electronic device programmed to perform the method according to any one of claims 1 to 18.

20. A computer program product comprising a computer-readable medium, the computer-readable medium having computer-readable code embodied therein, the computer-readable code being configured to cause a suitable computer or processor to execute the method according to any one of claims 1 to 13 when executed by the computer or processor.

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