Optimization of superstructures or mesiostructures in dental prostheses

Abstract

Method for creating a geometry of a mesiostructure for a dental prosthesis, wherein the method comprises the following steps: Receiving initial 3D data, which define a 3D construction space for a mesiostructure, Receiving second 3D data, which define possible positions for fixing the mesiostructure, Receiving third-party 3D data that defines possible positions or areas for fixing the dental prosthesis to the mesiostructure, and Creating an optimized geometry of the mesiostructure using an optimization procedure, whereby, starting from the 3D construction space, the possible positions for attaching the mesiostructure and the possible positions or areas for fixing the dental prosthesis to the mesiostructure, the geometry of the mesiostructure is optimized using the physical laws, the geometry of the mesiostructure is optimized by removing areas from the 3D design space that do not contribute to the load bearing or only contribute minimally.

Description

[0001] The invention relates to a method and a system for creating a geometry of a mesioconstruction for a dental prosthesis, and a method for producing a mesioconstruction for a dental prosthesis.

[0002] Furthermore, the invention relates to a computer-readable medium with computer-executable program code instructions for carrying out such a method, as well as to a computer program with program code means for carrying out such a method when the program is executed on a computer.

[0003] Furthermore, the invention relates to a superstructure or mesiostructure which is produced using the data generated by the method according to the invention.

[0004] Different types of dentures are known in the state of the art.

[0005] For example, a distinction is made between removable dentures and fixed dentures.

[0006] Both types of dentures can be attached to existing, crowned teeth and / or implants. In many cases, especially with dentures that require a large number of abutments (tooth stumps, dental implants, or post abutments) and / or are intended to replace a large number of missing teeth, it is not possible or practical to attach the denture directly to the abutments. In these cases, a mesiostructure, or sometimes called a superstructure, is attached to the abutments, and the denture itself is fixed to the mesiostructure.

[0007] Usually, after the preparation of the pillars (tooth stumps, dental implants, or post abutments), an “impression” of the situation in the mouth in the area of ​​the dental prosthesis to be made is taken, e.g. by means of a corresponding negative impression, which is converted in a dental laboratory into a positive model, e.g. a plaster model, which corresponds exactly to the situation in the mouth.

[0008] Alternatively, the interior of the mouth can also be “measured” using a 3D surface scan, preferably using an intra-oral scanner.

[0009] A CAD designer, such as a dental technician, then creates, usually with considerable effort, a computer model of a suitable mesiostructure for the dental prosthesis. This can be done manually, for example, using a CAD program. The number and arrangement of additional required attachment points, in particular implants, are determined, taking into account existing attachment options for the mesiostructure, such as remaining teeth or existing implants. When dimensioning the mesiostructure and defining the (additional) required implants, the dental technician usually relies on his or her knowledge and experience or on the empirical values ​​of other dental technicians. However, the respective individual biomechanical properties of the jaw are hardly taken into account, or at least not sufficiently taken into account, and in most cases the statics of the mesiostructure are not calculated precisely.

[0010] This can in particular result in implants being placed which do not bear any load, i.e. implants which are subjected to almost no or only very low forces when chewing with a denture in place, and are therefore actually considered superfluous.

[0011] In addition, the dental technician often makes the mesiostructures or parts of them larger than physically necessary to ensure that the mesiostructure is sufficiently stable. This leads to additional costs and can also have adverse aesthetic effects.

[0012] US 2015 / 0320520 A1 discloses a method for creating a mesiostructure geometry for a dental prosthesis. The geometry of the mesiostructure is created using prefabricated structural shapes, such as cylinders, circles, ellipses, squares, or polygons, stored in a data storage device. Subsequently, a mechanical design analysis is performed for the created geometry, taking into account the material to be used.

[0013] The invention is based, among other things, on the object of providing a novel method and a novel system for creating the geometry of a mesiostructure for dental prostheses. It achieves this and other objects through the subject matter of the independent claims. Advantageous further developments are specified in the subclaims.

[0014] Advantageously, a method for creating a geometry of a mesioconstruction for a dental prosthesis is provided, the method comprising the following steps: receiving first 3D data which define a 3D construction space for a mesioconstruction, Receiving second 3D data that defines possible positions for fixing the mesioconstruction, Receiving third 3D data that defines possible positions or areas for fixing the denture to the mesiostructure, and Creating an optimized geometry of the mesioconstruction by means of an optimization process, whereby, starting from the 3D construction space, the possible positions for attaching the mesioconstruction and the possible positions or areas for fixing the dental prosthesis to the mesioconstruction, the geometry of the mesioconstruction is optimized using the laws of physics, in particular the laws of mechanics.

[0015] A topology optimization method can expediently be used as the optimization method, wherein the optimized geometry of the mesiostructure can advantageously be calculated with a computer with the aid of the topology optimization method.

[0016] Optimization methods allow geometries to be optimized with regard to defined target variables. In doing so, specifications, in particular objective functions and constraints, which will be explained in more detail later, can be defined that should be taken into account during the optimization. One such optimization method is topology optimization. In this case, a design space, a loading scenario, e.g. one or more loads, one or more load collectives or one or more displacements, and, if applicable, possible fixed points that are part of the optimized mesiostructure are specified. A single load can be a static biting force or displacement, while a load collective describes a series of loads, forces or displacements that arise during a chewing cycle or are intended to represent a chewing cycle.

[0017] It is assumed that either the force or load introduction occurs via the possible positions for fixing the mesioconstruction and the force dissipation or load dissipation occurs via the possible positions or areas for fixing the denture to the mesioconstruction, or that the force or load introduction occurs via the possible positions or areas for fixing the denture to the mesioconstruction and the force dissipation or load dissipation occurs via the possible positions for fixing the mesioconstruction.

[0018] To create a biomechanically optimized geometry of the mesioconstruction using topology optimization, a three-dimensional construction space is specified, which expediently defines the maximum spatial extent of the mesioconstruction. The treating dentist or oral surgeon ideally specifies the 3D construction space, taking practical and aesthetic aspects into account. Theoretically, the entire oral cavity could initially be considered as the construction space, but the prosthesis should still be suitably positioned, the tongue should have sufficient space and freedom of movement, and the mesioconstruction should normally be invisible. Consequently, it is advisable for the dentist / oral surgeon to specify the largest possible 3D construction space as a starting point for optimization, while still meeting the aforementioned criteria.

[0019] Alternatively, an initial shape for a mesio construction can be specified as a 3D construction space.

[0020] The geometry of the mesiostructure is advantageously optimized by removing areas that contribute little or nothing to load absorption or load transfer from the 3D design space. The areas that contribute little or nothing to load absorption or load transfer are determined by simulating the forces and / or displacements acting on individual areas of the mesiostructure. A load absorption that is less than a certain limit is referred to as "insignificant load absorption" or "insignificant contribution to load absorption," whereby the limit can be defined in advance or specified by the user.

[0021] In this way, starting from the given 3D construction space, the geometry of the mesio construction is successively optimized in several iterations in which the areas that do not or only insignificantly contribute to the load bearing are removed from the remaining 3D construction space.

[0022] Furthermore, possible positions for fixing the mesioconstruction are defined to optimize the mesioconstruction.

[0023] The possible positions for fixing the mesioconstruction may include possible positions for one or more implants and / or, in the event that the patient still has at least one tooth of his or her own that, after appropriate preparation, is suitable for fixing the mesioconstruction, the position of the existing tooth(s) that is / are used to fix the mesioconstruction.

[0024] The possible position(s) for the insertion of one or more implants to secure the mesiostructure are preferably specified by the treating dentist or oral surgeon. The dentist / oral surgeon determines the possible position(s) for the insertion of one or more implants based on suitable examinations of the bone structure of the upper and / or lower jaw or on existing findings, ensuring reliable fixation of the mesiostructure and thus a good fit of the attached prosthesis, even under load.

[0025] The dentist or oral surgeon will also specify the position(s) of the remaining tooth(s) that, after appropriate preparation, are suitable for attaching the mesiostructure. If necessary, they will re-determine the current positions of the existing tooth(s) to achieve the greatest possible precision. If one or more additional implants are required to attach the mesiostructure, to which the prosthesis is to be fixed, the dentist or oral surgeon will specify one or more possible positions for these, as described above.

[0026] In addition, in order to optimize the mesioconstruction, possible positions or areas are defined which are suitable for fixing the denture to the mesioconstruction.

[0027] The positions or areas where the denture can be attached depend on the type and quality, i.e., the individual design, of the denture and the type of mesioconstruction, e.g., bar, attachment, or special design. The positions or areas where the denture can be attached are also preferably specified by the treating dentist / oral surgeon or prosthodontist.

[0028] If the respective mesioconstruction is designed in such a way that the position of the fixation points or fixation areas for the prosthesis is variable, i.e. not fixed, the arrangement of these fixation points or fixation areas for the prosthesis can also be biomechanically optimized.

[0029] In a preferred embodiment of the invention, the number of possible positions for implants is greater than the number of implants required for fixing the mesioconstruction, so that when optimizing the geometry of the mesioconstruction, those positions for implants can be determined from the total number of possible positions for implants which are best suited for fixing the mesioconstruction. In this way, the arrangement of the implants for fixing the mesioconstruction is also biomechanically optimized by determining a suitable subset of positions for implants from the total number of possible positions for implants. In this way, for example, a possible position for an implant which does not bear any or no significant load can be removed, and on the other hand, excessive loading of an individual implant orExcessive load bearing on a single implant should be avoided. A load bearing that is less than a certain limit is referred to as "no significant load bearing," whereby the limit can be defined in advance or set by the user.

[0030] Advantageously, at least one of the following objectives can be specified for optimising the geometry of the mesiostructure for a loading scenario: minimising the compliance of the mesiostructure; Minimizing displacement at a point or area; Minimizing the reaction force at the possible positions for fixing the mesioconstruction; minimizing the volume of the mesioconstruction and / or minimizing the weight of the mesioconstruction.

[0031] Advantageously, at least one predetermined condition can be taken into account when optimising the geometry of the mesiostructure, wherein the at least one predetermined condition includes at least one of the following conditions: permissible maximum reaction force at the possible positions for fixing the mesiostructure; permissible maximum reaction force at the possible positions or areas for fixing the denture to the mesiostructure; maximum permissible volume of the mesioconstruction; maximum permissible weight of the mesiostructure; permissible maximum compliance of the mesiostructure; and / or permissible maximum stresses.

[0032] Additionally, at least one fixed point of the mesiostructure geometry can be specified as an additional condition. If at least one fixed point is specified, this fixed point is necessarily included in the optimized mesiostructure geometry.

[0033] The optimization of the geometry of the mesioconstruction can be individualized by specifying an expected maximum load of the entire mesioconstruction or, more precisely, an expected maximum load scenario with regard to the chewing or biting force of the person for whom the mesioconstruction and denture are being made.

[0034] For example, the mesioconstruction can be made smaller or less powerful for a person with a relatively low maximum bite force, which is particularly advantageous for individuals with a small oral cavity. Conversely, for a person with a high maximum bite force, the mesioconstruction can be made stronger or larger, thus preventing overloading of individual sections of the mesioconstruction and thus preventing deformation or even breakage of the mesioconstruction.

[0035] If different materials are available for the mesiostructure, their properties can be taken into account when optimizing the geometry of the mesiostructure by adapting the permissible maximum load of individual sections of the mesiostructure to the respective material.

[0036] Furthermore, overloading of individual implants can be avoided by specifying a permissible maximum reaction force at the possible positions for fixing the mesiostructure, for example, a permissible maximum load for an individual implant. Here, too, by specifying an expected maximum load for the entire mesiostructure, or more precisely, an expected maximum total load capacity across the possible positions for fixing the denture, the optimization of the mesiostructure can be individualized with respect to the biting force of the person for whom the mesiostructure and denture are being made.

[0037] The maximum volume or maximum weight of the mesioconstruction, permissible maximum stresses, and / or a permissible maximum compliance of the mesioconstruction can also be specified as additional conditions. For example, the permissible maximum compliance can be specified as a maximum of 1 mm in a defined point or area (e.g., the location of the fixation of the prosthesis and mesioconstruction).

[0038] If different materials are available for the mesiostructure, these can also be taken into account when optimizing the geometry of the mesiostructure by adapting the maximum weight, the permissible maximum stresses and / or the permissible maximum compliance of the mesiostructure to the respective material.

[0039] By specifying a combination of various additional, material-dependent conditions, such as the permissible maximum load for individual sections of the mesiostructure, the maximum weight of the mesiostructure, the permissible stresses, and / or the permissible maximum compliance of the mesiostructure, the corresponding combination of conditions adapted to the respective material can be specified or tested for each available material. Thus, when optimizing the geometry of the mesiostructure, the material to be used can also be "optimized," i.e., the material most suitable for the individual specifications of the mesiostructure can be determined.

[0040] Advantageously, the above-mentioned objectives (objective functions) and conditions (constraints) can be combined in a suitable manner, ie meaningfully.

[0041] Thus, compliance can be minimized for a given load scenario and a given volume reduction (e.g., 70%), or the volume or mass can be minimized for a permissible maximum stress (and derived from this, the service life) and / or for a permissible maximum reaction force (e.g., 30N) on the implants.

[0042] The expected maximum load scenario for each person can be determined or estimated using individual measurements, a preliminary calculation, e.g. using FEM, or with the help of specialist literature.

[0043] Furthermore, manufacturing-related constraints on the geometry and / or structure of the mesiostructure may also be specified for optimization. For example, if the mesiostructure is to be milled, the geometry of the mesiostructure should be such that it can be milled, for example, it should not have any closed cavities.

[0044] When optimizing the geometry of the mesiostructure, areas that contribute little or nothing to load bearing are advantageously removed from the 3D design space. During the optimization process, the mechanical loads are simulated, for example, using the finite element method (FEM), to determine those areas of the mesiostructure that contribute little or nothing to load bearing. Thus, in an iterative process, the geometry of the mesiostructure is successively improved, starting with the 3D design space, until a biomechanically optimized geometry for the mesiostructure is achieved.

[0045] In a further preferred embodiment, the mesiostructure can be part of a one-piece construction comprising the mesiostructure and a dental prosthesis. Thus, in a one-piece design of the mesiostructure and dental prosthesis, the geometry of the part corresponding to the mesiostructure can be optimized using the method according to the invention.

[0046] According to a further aspect of the invention, a method for producing a mesioconstruction for a dental prosthesis is provided, the method comprising the following steps: Creating a geometry of a mesioconstruction for a dental prosthesis according to the method defined and explained in the previous paragraphs for creating a geometry of a mesioconstruction for a dental prosthesis and Manufacturing the mesioconstruction for a dental prosthesis based on the created geometry of the mesioconstruction for a dental prosthesis using a manufacturing process, e.g. using a generative / additive manufacturing process or milling.

[0047] The mesioconstruction can be made of a metal or metal alloy, a plastic or a ceramic.

[0048] Cobalt, chromium, molybdenum, titanium, or alloys of these metals with another metal, especially molybdenum, can advantageously be used. Zirconium oxide or even plastics, which are oral-compatible and non-toxic, can also be used.

[0049] For the production or manufacturing of the mesiostructure based on the previously created geometry of the mesiostructure for a dental prosthesis, a suitable manufacturing or production process can be selected depending on the desired material for the mesiostructure. These can be generative manufacturing processes, also known as additive manufacturing processes or 3D printing, such as sintering, laser sintering, selective laser melting, or electron beam melting for metals and metal alloys, and stereolithography or fused deposition modeling for plastics. Mesiostructures made of metal or metal alloys can also be milled, whereby the manufacturing-related limitations of milling are advantageously already taken into account when creating the geometry of the mesiostructure.

[0050] Compared to other manufacturing processes, such as milling, additive manufacturing processes have the advantage that almost any geometry can be manufactured with these processes and therefore no manufacturing-related restrictions need to be taken into account when creating or optimizing the geometry of the mesio construction.

[0051] According to a further aspect of the invention, a mesioconstruction is provided which has been manufactured using the method for manufacturing a mesioconstruction described above.

[0052] According to a further aspect of the invention, a device or a system is provided which is configured to carry out the method defined and explained in one of the preceding paragraphs for creating a geometry of a mesioconstruction and / or for producing a mesioconstruction.

[0053] According to a further aspect of the invention, a computer-readable medium is provided with computer-executable program code instructions for carrying out the method defined and explained in one of the preceding paragraphs for creating a geometry of a mesioconstruction and / or for producing a mesioconstruction.

[0054] According to a further aspect of the invention, a computer program is provided with program code means for carrying out the method defined and explained in one of the preceding paragraphs for creating a geometry of a mesio construction and / or for producing a mesio construction.

[0055] The invention is explained in more detail below with reference to several exemplary embodiments and the accompanying drawings. The drawing shows: Fig. 1 a first example of a mesioconstruction; and Fig. 2 a second example of a mesioconstruction.

[0056] First, the use of the terms “supraconstruction” and “mesioconstruction” should be explained in more detail.

[0057] The term "superstructure" usually refers to all parts that are placed or attached to the implants or abutments. A "mesiostructure" refers to an intermediate element, such as bars, attachments, or special designs, that is placed between the implants and the prosthesis or denture. Thus, the term "superstructure" includes both the mesiostructure and the prosthesis. However, this distinction is not always strictly applied, so that sometimes only the intermediate element, such as a bar or attachment, is referred to as a "superstructure." There is also no exact equivalent in English for the German term "mesiostructure." The English term "superstructure" can therefore also refer to the intermediate element, in particular the bar or attachment. Fig. 1 and Fig. 2 show various examples of mesioconstructions.

[0058] Optimization methods allow geometries to be optimized with regard to defined target parameters. Additional conditions can be defined that should be taken into account during the optimization. One such optimization method is topology optimization. In this case, a design space, a load effect and possible fixed points are specified. Based on this, a computer calculates a geometry while taking objective functions and constraints into account. The geometry is designed in such a way that, for example, with the smallest possible volume (or weight) or other objectives or objective functions while observing at least one constraint (e.g. maximum permissible stress), the best geometric structure is created, in the sense that the load is ideally distributed. For this purpose, all areas that do not contribute, or only contribute insignificantly, to load absorption are removed, whereby this is done while observing the constraint (e.g. a specified stress value is not exceeded).Alternatively, compliance could be minimized as an objective function, with a volume reduction of, for example, 70% (constraint condition) being specified.

[0059] This procedure will now be used for the construction of mesioconstructions, which are generally used to attach dentures to the jaw.

[0060] Topology optimization is intended to completely redesign the existing process. The dentist specifies possible positions for the implants. Based on the oral cavity and the denture, a possible design space (construction space) for the superstructure is then defined. Additional information includes the position(s) and magnitude of the force introduction. Using this information, the computer then calculates the optimal geometry of the superstructure using topology optimization and other methods such as the finite element method, so that, for example, minimal weight is achieved with maximum rigidity or a defined service life.

[0061] This results in a biomechanically optimized form of the superstructure and, if necessary, further information, such as which implant(s) is / are not required, since no load is introduced via it / these.

[0062] A further effect is that a CAD designer (e.g. dental technician) is not required or only required to a limited extent, since the previously manual drawing of the superstructure is largely taken over by a computer algorithm in the special CAD programs.

[0063] Apart from the defined installation space, the automatically calculated superstructure is hardly subject to any geometric constraints when it is manufactured using 3D manufacturing processes, which can produce almost any geometry.

[0064] When dimensioning the mesiostructure and defining the (additional) required implants, the dental technician typically relies on his or her knowledge and experience, or on the experience of other dental technicians. However, the individual biomechanical properties of the jaw are rarely, or at least insufficiently, taken into account, and the statics of the mesiostructure are often not precisely calculated.

[0065] The method according to the invention is particularly helpful when creating the geometry of a mesioconstruction for an "abnormal" jaw, i.e., a jaw in which bone areas are missing, e.g., due to tumor resection. In such a case, the implants required for the mesioconstruction can only be anchored in the bone at specific locations, which may lead to poor load distribution and necessitate a special geometry of the mesioconstruction, a so-called "special design." An example of such a special design is shown in Fig. 2.

[0066] Manually creating the geometry of such a special design for a mesioconstruction using a CAD program without taking into account the biomechanical properties of the jaw and the statics of the mesioconstruction can easily lead to a very unfavorable load distribution or load transfer.

[0067] Furthermore, there is a risk that when manually creating the geometry of such a special design for a mesioconstruction using a CAD program without taking into account the biomechanical properties of the jaw and the statics of the mesioconstruction, implants are planned and placed which do not bear any load, i.e. implants which are subject to almost no or only very low forces when chewing with a denture in place, and thus the insertion of these implants would not have been necessary for fixing the mesioconstruction.

[0068] Furthermore, especially in these special cases, the dental technician often makes the mesiostructures or parts of them larger than physically necessary to ensure that the mesiostructure is sufficiently stable. This leads to additional costs and can also have adverse aesthetic effects.

[0069] Therefore, the method according to the invention is particularly helpful in creating the geometry of a mesioconstruction for an “abnormal” jaw that requires a special design.

[0070] The method according to the invention will be explained in more detail below.

[0071] A simulation based on a finite element method (FEM) is carried out on a computer using a simulation software program, such as ANSYS (computer program product), stored on its storage device or any other storage device.

[0072] A FEM mesh can be created, for example, using an FEM simulation software program stored on a storage device of the computer or on any other storage device of a separate computer, or a corresponding FEM meshing software.

[0073] For example, mechanical stresses that occur during later real use of the mesioconstruction (ie when chewing with the prosthesis inserted) can be simulated.

[0074] Starting from a 3D design space that defines the maximum spatial extent of the mesiostructure, the simulation described above is performed iteratively, with areas that contribute little or nothing to load absorption being removed at each iteration. More specifically, each element of the geometry to be optimized is assigned a pseudodensity with a value between 0 and 1, which describes whether the respective element is necessary in the design space (pseudodensity 1) or can be neglected (pseudodensity 0).

[0075] The treating dentist or oral surgeon ideally specifies the 3D construction space, taking practical and aesthetic aspects into account. For example, the prosthesis should still be suitable for positioning, the tongue should have sufficient space and freedom of movement, and the mesiostructure should normally be invisible. Therefore, the dentist / oral surgeon should specify the largest possible 3D construction space, while still meeting the aforementioned criteria, as a starting point for optimization.

[0076] The step-by-step biomechanical optimization of the mesiostructure geometry is advantageously performed automatically with the help of the topology optimization program. In each iteration, the remaining 3D build space is further reduced or adjusted according to the specifications, i.e., objective function(s) and constraint(s), until a biomechanically optimized geometry is achieved in the final iteration.

[0077] After optimization, pseudodensities with values ​​between 0 and 1 are assigned to the build space. Typically, the majority of the values ​​are close to 0 or 1. However, values ​​in between are also possible. The distribution of the pseudodensity values ​​depends on the specific optimization.

[0078] The optimized geometry is now exported, with only those parts of the geometry whose pseudodensity lies within a specific range (e.g., 0.8 to 1) defined by a user or a specific logic being exported. Thus, the user or logic determines how much material is actually exported and thus the appearance of the optimized geometry.

[0079] The exported topology-optimized geometry is then smoothed.

[0080] Alternatively, an additional optimization method, such as shape optimization, could be used to reduce stress during post-processing of the optimized geometry. In contrast to topology optimization, shape optimization deforms (morphs) the surface in a defined area to further reduce stress peaks.

[0081] For the optimization of the mesioconstruction, possible positions for fixing the mesioconstruction are defined, which are excluded from the optimization, i.e. are in any case part of the optimized geometry of the mesioconstruction.

[0082] The possible positions for fixing the mesioconstruction may include possible positions for one or more implants and / or, in the event that the patient still has at least one of his or her own teeth that, after appropriate preparation, is suitable for fixing the mesioconstruction, the position of the existing tooth(s) that will be used to fix the mesioconstruction.

[0083] The possible positions for inserting implants to secure the mesiostructure are preferably specified by the treating dentist or oral surgeon. They will determine these based on appropriate examinations of the bone structure of the upper and / or lower jaw or on existing findings, ensuring reliable fixation of the mesiostructure and thus a good fit of the attached prosthesis, even under load.

[0084] The dentist or oral surgeon will also specify the position(s) of the remaining tooth(s) that, after appropriate preparation, are suitable for attaching the mesiostructure. If necessary, they can re-determine the current positions of the existing tooth(s) to achieve the greatest possible precision. If one or more additional implants are required to secure the mesiostructure, to which the prosthesis is to be fixed, the dentist / oral surgeon will specify one or more possible positions for these, as described above.

[0085] In addition, in order to optimize the mesioconstruction, possible positions or areas are defined which are suitable for fixing the denture to the mesioconstruction.

[0086] The positions or areas where the denture can be attached depend on the type and quality, i.e., the individual design, of the denture and the type of mesioconstruction, e.g., bar, attachment, or special design. The positions or areas where the denture can be attached are also preferably specified by the treating dentist / oral surgeon or prosthodontist.

[0087] If the respective mesioconstruction is designed in such a way that the position of the fixation points or fixation areas for the prosthesis is variable, i.e. not fixed, the arrangement of these fixation points or fixation areas for the prosthesis can also be biomechanically optimized.

[0088] In a preferred embodiment of the invention, the number of possible positions for implants is greater than the number of implants required for fixing the mesioconstruction, so that when optimizing the geometry of the mesioconstruction, those positions for implants can be determined from the total number of possible positions for implants which are best suited for fixing the mesioconstruction. Thus, the arrangement of the implants for fixing the mesioconstruction is also biomechanically optimized by determining a suitable subset of positions for implants from the total number of possible positions for implants. In this way, for example, possible positions for implants at which no or no significant load is absorbed can be removed, and on the other hand, excessive loading of an individual implant or excessive load absorption on an individual implant can be avoided.

[0089] For this purpose, the area of ​​the mesiostructure that comes into contact with the corresponding implant is considered, i.e., the area through which the force is directly introduced / absorbed between the implant and the mesiostructure. If no (significant) load is absorbed in a specific area of ​​the mesiostructure, then no (significant) load is absorbed by the corresponding implant that comes into contact with that specific area of ​​the mesiostructure either.

[0090] Advantageously, at least one of the following objectives or objective functions can be specified for the optimization of the geometry of the mesioconstruction: The volume or mass of the mesiostructure can be minimized, for example, by removing areas that do not or only slightly contribute to load absorption or load transfer.

[0091] The compliance of the mesiostructure can be minimized, and this can be done for any load scenario, e.g., for a single specified load or for a load collective. The load scenario used is based on the biting force (or chewing force) of the person for whom the mesiostructure and denture are being fabricated.

[0092] Thus, the geometry of the mesioconstruction can be individually optimized for a static bite force of a specific person, as well as for several load cases that, for example, represent a chewing cycle of a specific person.

[0093] Furthermore, the displacement at a specific point or region of the mesiostructure, which can be arbitrarily defined, can be minimized according to an objective function and / or constraint function.

[0094] The reaction force at the possible positions for fixing the mesioconstruction, e.g. at all implants or even at a single implant, can also be minimized.

[0095] When optimizing the geometry of the mesiostructure, at least one given condition, often referred to as a constraint, can be taken into account.

[0096] For example, at least one fixed point of the mesio-construction geometry can be specified as an additional condition. If at least one fixed point is specified, this at least one fixed point is necessarily included in the optimized mesio-construction geometry.

[0097] A permissible maximum load for individual sections of the mesiostructure can also be specified.

[0098] The optimization of the geometry of the mesioconstruction can be individualized by specifying an expected maximum load of the entire mesioconstruction or, more precisely, an expected maximum total load absorption across the possible positions for fixing the denture, with regard to a load scenario of the person for whom the mesioconstruction and denture is being made.

[0099] For example, the mesioconstruction can be made smaller or less powerful for a person with a relatively low maximum bite force, which is particularly advantageous for individuals with a small oral cavity. Conversely, for a person with a high maximum bite force, the mesioconstruction can be made stronger or larger, thus preventing overloading of individual sections of the mesioconstruction and thus preventing deformation or even breakage of the mesioconstruction.

[0100] If different materials are available for the mesiostructure, their properties can be taken into account when optimizing the geometry of the mesiostructure by adapting the permissible maximum load of individual sections of the mesiostructure to the respective material.

[0101] Furthermore, overloading of individual implants can be avoided by specifying a permissible maximum reaction force at the possible positions for fixing the mesiostructure, for example, a permissible maximum load for an individual implant. Here, too, by specifying an expected maximum load for the entire mesiostructure, or more precisely, an expected maximum total load capacity across the possible positions for fixing the denture, the optimization of the mesiostructure can be individualized with respect to a loading scenario specific to the person for whom the mesiostructure and denture are being fabricated.

[0102] If, even after optimizing the geometry of the mesiostructure, increased loading of a particular implant cannot be avoided, the implant can be adjusted accordingly. In particular, the length or diameter of the implant can be increased.

[0103] The permissible maximum volume or the permissible maximum weight of the mesiostructure, permissible maximum stresses and / or a permissible maximum compliance of the mesiostructure can also be specified as additional conditions.

[0104] If different materials are available for the mesiostructure, these can also be taken into account when optimizing the geometry of the mesiostructure by adapting the maximum weight, the permissible maximum stresses and / or the permissible maximum compliance of the mesiostructure to the respective material.

[0105] By specifying a combination of various additional, material-dependent conditions, such as the permissible maximum load for individual sections of the mesiostructure, the permissible maximum weight of the mesiostructure, the permissible maximum stresses, and / or the permissible maximum resilience of the mesiostructure, the corresponding combination of conditions adapted to the respective material can be specified or tested for each available material. Thus, when optimizing the geometry of the mesiostructure, the material to be used can also be "optimized," i.e., the material most suitable for the individual specifications of the mesiostructure can be determined.

[0106] Advantageously, the above-mentioned objectives (objective functions) and conditions (constraints) can be combined in a suitable or meaningful way.

[0107] Thus, compliance can be minimized for a given load or load spectrum and a given volume reduction (e.g. 70%), or the volume or mass can be minimized for a permissible maximum stress (and derived from this the service life) and / or for a permissible maximum reaction force (e.g. 30N) on the implants.

[0108] The expected maximum load scenario for each person can be determined or estimated using individual measurements, a preliminary calculation, e.g. using FEM, or with the help of specialist literature.

[0109] In a further preferred embodiment, the mesiostructure can be part of a one-piece construction comprising the mesiostructure and a dental prosthesis. Thus, in a one-piece design of the mesiostructure and dental prosthesis, the geometry of the part corresponding to the mesiostructure can be optimized using the method according to the invention.

[0110] After optimization, pseudodensities with values ​​between 0 and 1 are assigned to the build space. Typically, the majority of the values ​​are close to 0 or 1. However, values ​​in between are also possible. The distribution of the pseudodensity values ​​depends on the specific optimization.

[0111] The optimized geometry is now exported, with only those parts of the geometry whose pseudodensity lies within a specific range (e.g., 0.8 to 1) defined by a user or a specific logic being exported. Thus, the user or logic determines how much material is actually exported and thus the appearance of the optimized geometry.

[0112] The exported topology-optimized geometry is smoothed and, if necessary, further processed by a dental technician, for example, whereby the dental technician also has the option of changing the position of the fixation points for implants and dentures if necessary.

[0113] Alternatively, an additional optimization method, such as shape optimization, could be used to reduce stress during post-processing of the optimized geometry. In contrast to topology optimization, shape optimization deforms (morphs) the surface in a defined area to further reduce stress peaks.

[0114] The smoothed and, if necessary, post-processed data is then converted into a suitable geometry format, e.g. an STL file or CAD file.

[0115] On this basis, a CAM (Computer-Aided Manufacturing) file can be generated if required.

[0116] Based on the generated data, e.g. STL, CAD, CAM data or any other file format required by the respective device for manufacturing, the mesiostructure can be manufactured using a suitable manufacturing process, e.g. 3D printing or an additive manufacturing process or milling.

[0117] The mesioconstruction can be conveniently made of a metal or a metal alloy or a plastic.

[0118] Cobalt, chromium, molybdenum, titanium, or alloys of these metals with another metal, especially molybdenum, can advantageously be used. Zirconium oxide or even plastics, which are oral-compatible and non-toxic, can also be used.

[0119] For the production or manufacturing of the mesiostructure based on the previously created geometry of the mesiostructure for a dental prosthesis, a suitable manufacturing or production process can be selected depending on the desired material for the mesiostructure. Generative manufacturing processes, also known as additive manufacturing or 3D printing, such as sintering, laser sintering, selective laser melting, or electron beam melting for metals and metal alloys, and stereolithography or fused deposition modeling for plastics, can be used. Mesiostructures made of metal or metal alloys can also be milled, whereby the manufacturing-related limitations of milling are advantageously already taken into account when creating the geometry of the mesiostructure.

[0120] Compared to other manufacturing processes, such as milling, additive manufacturing processes have the advantage that almost any geometry can be manufactured using these processes and therefore no manufacturing-related restrictions need to be taken into account when creating or optimizing the geometry of the mesio construction.

Claims

[1] Method for creating a geometry of a mesioconstruction for a dental prosthesis, the method comprising the following steps: Receiving initial 3D data that defines a 3D construction space for a mesio construction, Receiving second 3D data that defines possible positions for fixing the mesioconstruction, Receiving third 3D data that defines possible positions or areas for fixing the denture to the mesiostructure, and Creating an optimized geometry of the mesioconstruction using an optimization process, whereby, starting from the 3D construction space, the possible positions for attaching the mesioconstruction and the possible positions or areas for fixing the dental prosthesis to the mesioconstruction, the geometry of the mesioconstruction is optimized using the laws of physics, The geometry of the mesiostructure is optimized by removing areas that do not or only insignificantly contribute to load bearing from the 3D construction space. [2] The method of claim 1, wherein the optimization method includes a topology optimization method. [3] Method according to claim 2, wherein the optimized geometry of the mesiostructure is calculated with a computer using a topology optimization method. [4] Method according to one of the preceding claims, wherein the 3D construction space defines the maximum spatial extent of the mesioconstruction. [5] Method according to one of claims 1 to 3, wherein the 3D construction space is a starting shape for a mesio construction. [6] Method according to claim 1, wherein the areas which do not contribute or only contribute insignificantly to load absorption are determined by simulating the forces and / or displacements acting on individual areas of the mesiostructure. [7] Method according to one of the preceding claims, wherein the possible positions for fixing the mesioconstruction include possible positions of implants and / or positions of existing teeth. [8] Method according to claim 7, wherein the number of possible positions of implants is greater than the number of implants required for fixing the mesioconstruction [9] Method according to claim 8, wherein the geometry of the mesioconstruction is optimized by removing possible positions of implants at which no or no significant load bearing takes place. [10] Method according to one of the preceding claims, wherein at least one of the following objectives is specified for the optimization of the geometry of the mesioconstruction: Minimizing the volume of the mesioconstruction; Minimizing the weight of the mesiostructure; Minimizing the flexibility of the mesiostructure; Minimizing displacement at a point or area; and / or minimizing reaction forces at the possible positions for fixing the mesioconstruction. [11] Method according to one of the preceding claims, wherein at least one predetermined condition is taken into account in the optimization of the geometry of the mesiostructure, wherein the at least one predetermined condition includes at least one of the following conditions: one or more fixed points of the geometry of the mesioconstruction; permissible maximum load of individual sections of the mesiostructure; permissible maximum reaction force at the possible positions for fixing the mesioconstruction; permissible maximum reaction force at the possible positions or areas for fixing the denture to the mesiostructure; maximum permissible volume of the mesioconstruction; maximum permissible weight of the mesiostructure; permissible maximum flexibility of the mesiostructure; permissible maximum voltages and / or manufacturing-related restrictions on the geometry and / or structure of the mesioconstruction. [12] Method according to claims 10 and 11, wherein a suitable combination of the objectives for the optimization and the conditions for the optimization is selected for the optimization of the geometry of the mesiostructure. [13] Method according to one of the preceding claims, wherein the mesioconstruction is part of a one-piece construction comprising the mesioconstruction and a dental prosthesis. [14] A method for producing a mesioconstruction for a dental prosthesis, the method comprising the following steps: Creating a geometry of a mesioconstruction for a dental prosthesis according to the method according to one of the preceding claims and Manufacturing the mesiostructure for a dental prosthesis based on the created geometry of the mesiostructure for a dental prosthesis using a generative manufacturing process or by milling. [15] Mesioconstruction produced using the method according to claim 14. [16] System designed and arranged to carry out the method according to any one of claims 1-14. [17] A computer-readable medium comprising computer-executable program code instructions for carrying out a method according to any one of claims 1-14. [18] A computer program comprising program code means for performing a method according to any one of claims 1-14 when the program is executed on a computer.

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