MANUFACTURING PROCESS FOR A DENTAL OBJECT

Description

[0001] The present invention relates to a manufacturing method for a dental object and a manufacturing system for manufacturing a dental object.

[0002] In common digital workflows, dental restorations are created in CAD software and saved in a 3D CAD file format. Depending on the CAD software used and the subsequent workflow, so-called metadata containing additional information may be generated and saved along with the 3D CAD file. However, an orientation adjustment may be necessary for the production of a dental object.

[0003] Metadata can be helpful for controlling or optimizing ablation processes, such as assigning milling strategies for a specific restoration type. In three-dimensional printing processes that require support structures, such as stereolithography, VAT polymerization, 3D DLP printing, or selective laser sintering of metals, certain surfaces of dental restorations should be free of support structures to positively influence precision and surface quality.

[0004] However, metadata has the disadvantage that it is already generated in the CAD software and is a proprietary data format. In this case, the CAM software used must be able to import and interpret the associated proprietary metadata. Since these metadata formats are not universal, a separate interface must be programmed for each proprietary metadata format. If no metadata is available for an object, the CAM software cannot determine which indication it is during import.

[0005] The document US 10,856,957 B2 relates to a method for producing a three-dimensional digital model of a prosthesis base for manufacture using a light-based three-dimensional printing device, comprising positioning a virtual reference model next to a virtual build platform surface provided by software.

[0006] The document US 2006 / 008774 A1 relates to a method for producing a dental prosthesis from a blank by creating a processing plan for processing equipment and to a device for producing a dental prosthesis.

[0007] The technical object of the invention is to orient a digital dental object in such a way that it can subsequently be efficiently manufactured in a manufacturing process. This technical object is achieved by the subject matter according to the independent claims. Technically advantageous embodiments are the subject matter of the dependent claims, the description, and the drawings.

[0008] According to a first aspect, the technical problem is solved by a manufacturing method for a dental object, comprising the steps of generating a digital dental object in a coordinate system that describes a shape of the dental object to be manufactured; rotating the spatial orientation of the digital dental object in the coordinate system based on a digital reference object in the coordinate system, wherein the orientation of the digital dental object in the coordinate system is rotated until a spatial deviation between the digital dental object and the digital reference object falls below a predetermined value; and manufacturing the dental object based on the digital dental object with the rotated spatial orientation. The manufacturing method achieves an automatically optimized, production-specific orientation of dental indications for the digital manufacturing process.The deviation value can be determined from a spatial overlap area of the two objects. This provides the technical advantage, for example, of allowing the digital dental object and the digital reference object to be approximated in an iterative process.

[0009] In a technically advantageous embodiment of the manufacturing method, a size of the digital reference object is adapted to a size of the digital dental object and / or a size of the digital dental object is adapted to a size of the digital reference object. The sizes of the digital reference object and the digital dental object are adapted to each other by uniform scaling so that they are as similar as possible. This achieves, for example, the technical advantage of achieving a higher degree of correspondence or overlap between the digital dental object and the digital reference object.

[0010] In a further technically advantageous embodiment of the manufacturing method, a position of the digital dental object in the coordinate system is shifted based on a digital reference object in the coordinate system. This also achieves the technical advantage, for example, of achieving a greater correspondence or overlap between the digital dental object and the digital reference object.

[0011] In a further technically advantageous embodiment of the manufacturing method, the position of the digital dental object is shifted in the coordinate system until the spatial deviation between the digital dental object and the digital reference object falls below a predetermined value. This also achieves the technical advantage, for example, that the digital dental object and the digital reference object can be brought closer to each other in an iterative process.

[0012] In another technically advantageous embodiment of the manufacturing method, the dental object is manufactured using an additive manufacturing process. This achieves the technical advantage, for example, that the dental object can be easily manufactured in any desired shape.

[0013] In a further technically advantageous embodiment of the manufacturing method, a digital support structure based on the orientation of the reference object is added to the digital dental object with the rotated spatial orientation. The support structure can be added independently of the reference object. This achieves the technical advantage, for example, that the digital support structure is automatically added at a designated and suitable location. This can improve and accelerate the production of the dental object. This also achieves the technical advantage, for example, that the support structure can be automatically arranged on designated and suitable surfaces.

[0014] In another technically advantageous embodiment of the manufacturing method, the dental object is manufactured using a subtractive manufacturing process. This also achieves the technical advantage that the dental object can be manufactured in a simple manner.

[0015] In a further technically advantageous embodiment of the manufacturing method, a digital support structure based on the orientation of the reference object is added to the digital dental object with the rotated spatial orientation. This achieves the technical advantage, for example, that support bars for holding a milled dental object are automatically arranged only at suitable locations on the dental object. This achieves the technical advantage, for example, that the support structure can be automatically arranged on designated and suitable surfaces.

[0016] In another technically advantageous embodiment of the manufacturing method, the digital reference object can be retrieved from a database containing multiple digital reference objects. A different reference object can be retrieved for different manufacturing processes, such as 3D printing, a pressing process, a casting process, or post-treatment. In this case, the manufacturing process is first selected, and the reference object for the manufacturing process is retrieved from the database. This provides the technical advantage, for example, of achieving optimal orientation of the dental object depending on the manufacturing process.

[0017] In another technically advantageous embodiment of the manufacturing method, the digital dental object includes data about an indication. This provides the technical advantage, for example, of being able to select a suitable reference object depending on the indication.

[0018] In a further technically advantageous embodiment of the manufacturing method, the digital reference object can be retrieved from a database based on the data about the indication or can be assigned. The digital reference object can also be manually selected or determined. This achieves the technical advantage, for example, that different reference objects for different indications can be retrieved and / or assigned to the digital dental object.

[0019] According to a second aspect, the technical problem is solved by a manufacturing system for producing a dental object, comprising a computer program comprising instructions that, when executed by a computer, cause the computer to carry out the method according to the first aspect. This achieves the same technical advantages as the method according to the first aspect.

[0020] Embodiments of the invention are illustrated in the drawings and are described in more detail below.

[0021] They show: Fig. 1 shows a schematic view of the manufacturing process for a dental object; Fig. 2 shows a dental object with support or holding structures; and Fig. 3 shows a block diagram of a manufacturing process for a dental object.

[0022] Fig. 1 shows a schematic view of the manufacturing process for a real dental object 100-2 based on a digital dental object 100-1. The real dental object 100-2 is, for example, a crown, a bridge, a veneer, an abutment, an inlay, an onlay, a splint, or a partial or full denture. In general, the dental object 100-2 can be any object in the dental field that is to be manufactured using a three-dimensional manufacturing process, such as a 3D printing process or milling process.

[0023] First, the CAD software creates a digital dental object 100-1 in a coordinate system that describes a shape of the dental object 100-2 to be manufactured. The digital dental object 100-1 is initially oriented in an arbitrary orientation in the coordinate system. The digital dental object 100-1 serves a specific indication. The shape of the digital dental object 100-1 is specified, for example, by a set of triangles or coordinates that define the surface of the digital dental object 100-1. The digital dental object 100-1 can be stored in a data set.

[0024] A database 107 comprises a plurality of digital reference objects 100-R, each of which is assigned, for example, an indication and a manufacturing method.

[0025] The reference object 100-R specifies a reference shape with a specific reference position and orientation within the coordinate system. The shape of the digital dental object 100-R, for example, is also specified by a set of triangles or coordinates that define the surface of the reference object 100-R. The digital reference object 100-R can also be stored in a data set.

[0026] In addition to the indication, the following information can be stored in database 107 for the reference object 100-R: Description of the orientation of the reference object 100-R using dental terminology; which surfaces 109-1 may be occupied by support or holding structures 103 or 105 (support requirement); and which surfaces 109-2 may not be occupied by support or holding structures 103 or 105 (support prohibition).

[0027] The surfaces 109-1 and 109-2, which describe commands and prohibitions for a support or holding structure on the reference object 100-R, can be transferred to the digital dental object 100-1.

[0028] A digital reference object 100-R of an indication corresponding to the indication of the digital dental object 100-1 is loaded from the database 107. If the indication of the digital dental object 100-1 is, for example, an inlay, the digital reference object 100-R for an inlay is loaded from the database 107.

[0029] If both the digital dental object 100-1 and the reference object 100-R are loaded, the digital dental object 100-1 is scaled to a similar size as the reference object 100-R, or vice versa. Alternatively, the dental object 100-1 and the reference object 100-R can be scaled to a common, similar size. The aspect ratio should not change. Various rotation or translation operations are then performed on the digital dental object 100-1, such as rotating the digital dental object 100-1 around a Y-axis. During a translation, the centers of mass of the digital dental object 101-1 and the reference object 101-R can be superimposed. The scaling, rotation, and translation serve the purpose of achieving maximum overlap between the digital dental object 100-1 and the reference object 100-R.

[0030] An overlap can be calculated by adjusting the Jaccard coefficient of the digital dental object 101-1 and the reference object 101-R. To calculate the overlap, the spatial intersection between the digital dental object 100-1 and the reference object 100-R can be calculated.

[0031] For this purpose, the scaling and rotation or translation operations can be repeated iteratively until a spatial deviation between the digital dental object 100-1 and the digital reference object 100-R falls below a predetermined value. The deviation can be calculated as a volume-based coverage ratio. The coverage ratio can be a ratio-scaled number between 0 and 1, which can be viewed as a percentage.

[0032] For the calculation, the digital dental object 100-1 and the reference object 100-R are transformed into a voxel representation. All empty voxels within both objects are then filled. The number of voxels occupied by both objects is divided by the total number of filled voxels. This corresponds to a calculation of the Jaccard coefficient of two sets, also known as intersection over union (IoU). The calculated value, between 0 and 1, indicates the extent to which the two three-dimensional objects match. This value can be maximized by translating and rotating the objects.

[0033] The superposition and iterative alignment are performed using the best-fit method. The digital dental object 100-1 is scaled and transformed rotationally and translationally until maximum overlap with the reference object 100-R is achieved. This allows the orientation and position of the digital dental object 100-1 to be determined that is adapted to the orientation and position of the reference object 100-R in the coordinate system.

[0034] The thus transformed digital dental object 100-1 is saved in the coordinate system of the reference object 100-R. The digital dental object 100-1 is then saved in this new orientation and position in the coordinate system and made available for subsequent processing steps in the CAM software for production preparation. After the production-specific data preparation, the real dental object 100-2 is then manufactured.

[0035] The manufacturing system 200 is, for example, a 3D printer. In general, the manufacturing system 200 is any system suitable for manufacturing the dental object. The manufacturing system 200 includes, for example, a computer with a digital memory and a processor for executing a computer program that implements individual steps of the manufacturing method.

[0036] The coordinate system of the reference object 100-R is ideally identical to the coordinate system for the manufacturing system 200, such as the coordinate system of a 3D printer's build space. In 3D DLP printing, a stereolithography manufacturing process, the dental object 100-2 is built layer by layer from bottom to top (bottom up).

[0037] The common coordinate system with the X and Y axes spans the build platform, and the Z axis points away from the build platform. In this coordinate system, the aligned digital dental object 100-1 is prepared in the CAM software for further build job preparation. Preparation includes, among other things, data repair, the creation of support or holding structures 103 or 105, nesting, and / or slicing.

[0038] Overall, the automatic and production-specific orientation of the digital dental object 100-1 is achieved by overlaying, adjusting, comparing, and transforming the digital dental object 100-1 with the reference object 100-R of a suitable indication. The selection or determination of the dental indication can also be performed manually.

[0039] The optimized alignment of the digital dental object 100-1 based on the reference object 100-R enables the dental object 100-1 to be manufactured as quickly as possible, the requirements and prohibitions for holding or supporting structures are complied with as best as possible, it requires as few holding or supporting structures 103 or 105 as possible, and indication-relevant surfaces of the dental object 100-2 do not have to be reworked.

[0040] CAM software allows dental technology expertise to be implemented into optimal digital manufacturing processes. The CAM software provides optimal orientation of dental objects 100-1 for the respective manufacturing process, such as additive or subtractive manufacturing. This allows for consideration of production time, resulting quality in terms of fit and surface quality, and minimal rework effort for the user.

[0041] These results can in turn be fed back into the database 107, such as a look-up table, so that a new three-dimensional reference object 100-R is stored in the coordinate system by experts in an optimal position and orientation for the manufacturing process.

[0042] Fig. 2 shows a dental object 101-1 with support or holding structures 103 and 105. The dental workflow can be further improved using the CAM software by defining rules for generating support or holding structures 103 or 105 for the dental object 101-1. These support or holding structures 103 or 105 can be dependent on an indication, i.e., they can be indication-specific. If the indication of the imported dental object 101-1 is known to the CAD or CAM software, optimization measures can be implemented in the further workflow using a corresponding data set. The reference object 100-R for a specific indication is already oriented and positioned in such a way that it takes the dental work process into account or optimally supports it, and the do's and don'ts for holding or supporting structures 103 or 105 are adhered to as closely as possible.For example, a crown is oriented so that the occlusal surface and the cavity face to the side, and the thickest wall thickness faces the build platform. In this case, the occlusal surface and the cavity are considered forbidden surfaces, and the outer surface with the thickest wall thickness is considered the permitted surface for creating the support structure(s).

[0043] The support structures 103 support the finished dental object 100-2 on the build platform during 3D printing to ensure successful printing. The holding structures 105 hold the finished dental object 100-2 in position within a blank during and after a milling process.

[0044] For example, the reference object 100-R may contain surfaces 109-1 that are to be occupied by support or holder structures 103 or 105 (support or holding structure requirement) or surfaces 109-2 that may not be occupied by support or holder structures 103 or 105 (support or holding structure prohibition). Using dental technology expertise and knowledge of the respective manufacturing process (subtractive or additive), the reference object 100-R is oriented and positioned accordingly so that it takes the requirements and prohibitions for support or holding structures 103 or 105 into account as far as possible. Due to the adapted, automatic orientation of the digital dental object 101-1 according to the specifications of the reference object 100-R, these requirements and prohibitions are also indirectly taken into account for the digital dental object 101-1 through the new orientation.

[0045] This results in similar, indication- and production-specific support or holding structures 103 or 105 for the dental object 101-1. The parameters to be used for the support or holding structures 103 and 105 can also be stored in the reference object 100-R, such as a characteristic (thickness, contact area) and / or density / number of the support or holding structures 103 and 105.

[0046] A CAM software can then automatically generate the required support or holding structures 103 or 105 according to its rules / algorithms on the basis of the specified parameters, so that the construction order can be manufactured as quickly and stably as possible with as few support or holding structures 103 or 105 as possible.

[0047] Fig. 3shows a block diagram of a manufacturing method for a dental object 100-2. The manufacturing method comprises the step of generating S101 a digital dental object 100-1 in a coordinate system that describes a shape of the dental object 100-2 to be manufactured. The digital dental object 100-1 can be generated, for example, using a CAD (computer-aided design) process. In this CAD process, the shape and appearance of the digital dental object 100-1 are specified. The digital dental object 100-1 forms the basis for producing a real dental object 100-1.

[0048] In 3D modeling, the digital dental object 100-1 is created and saved in a three-dimensional form. This allows for a realistic representation. The digital dental object 100-1 can be saved and transferred as a data set, for example, as a file in STL format.

[0049] In step S102, the spatial orientation of the digital dental object 100-1 in the coordinate system is reoriented and / or positioned based on a digital reference object 100-R in the coordinate system. For this purpose, for example, the digital reference object 100-R, which has a defined orientation in the coordinate system, is loaded into a memory together with the digital dental object 100-1. The digital dental object 100-1 and the reference object 100-R are first brought to a similar size by uniform scaling. Then, for example, the orientation of the digital dental object 100-R in the coordinate system is rotated or the position of the digital dental object 100-1 in the coordinate system is shifted until a spatial deviation between the digital dental object 100-1 and the digital reference object 100-R becomes minimal or falls below a predetermined value.

[0050] In step S103, the real dental object 100-2 is manufactured on the basis of the digital dental object 100-1 with the rotated spatial orientation in a suitable manufacturing process.

[0051] Depending on the indication and a selected manufacturing process, the digital dental object 101-1 can be oriented, for example, in a blank, such as during milling, or in a build space, such as during 3D printing. The orientation is performed in such a way that the holding or support structures 103 or 105 automatically generated in the CAM software do not distort critical surfaces for the shape and function of the real dental object, a stable manufacturing process is guaranteed, and rework for the dental technician or dentist is minimized.

[0052] The assignment of an indication to the digital dental object 101-1 can already be done automatically by the CAD software and, for example, be included in the file name, or can be subsequently identified by the user in the CAM software and assigned to the digital dental object 101-1.

[0053] All features explained and shown in connection with individual embodiments of the invention can be provided in different combinations in the subject matter according to the invention in order to simultaneously realize their advantageous effects.

[0054] All method steps can be implemented by devices suitable for performing the respective method step. All functions performed by physical features can be a method step of a method.

[0055] The scope of the present invention is given by the claims and is not limited by the features explained in the description or shown in the figures. LIST OF REFERENCE SYMBOLS

[0056] 100-1 Digital dental object 100-2 Real dental object 100-R Digital reference object 103 Support structure 105 Holding structure 107 Database 109-1 Required area for support or holding structure 109-2 Forbidden area for support or holding structure 200 manufacturing system

Claims

1. A manufacturing method for a dental object (100-2), comprising the steps of: - generating (S101) a digital dental object (100-1) in a coordinate system that describes a shape of the dental object (100-2) to be manufactured; - rotating (S102) the spatial orientation of the digital dental object (100-1) in the coordinate system based on a digital reference object (100-R) in the coordinate system, wherein the orientation of the digital dental object (100-R) in the coordinate system is rotated until a spatial deviation between the digital dental object (100-1) and the digital reference object (100- R) is below a predetermined value; and - manufacturing (S103) the dental object (100-2) based on the digital dental object (100-1) with the rotated spatial orientation.

2. The manufacturing method according to claim 1, wherein a size of the digital reference object (100-R) is adapted to a size of the digital dental object (100-1) and / or a size of the digital dental object (100-1) is adapted to a size of the digital reference object (100-R).

3. The manufacturing method according to any one of the preceding claims, wherein a position of the digital dental object (100-1) in the coordinate system is shifted based on a digital reference object (100-R) in the coordinate system.

4. The manufacturing method according to any one of the preceding claims, wherein the position of the digital dental object (100-1) in the coordinate system is shifted until a spatial deviation between the digital dental object (100-1) and the digital reference object (100-R) is below a predetermined value.

5. The manufacturing method according to any one of the preceding claims, wherein the dental object (100-2) is manufactured by means of an additive manufacturing method.

6. The manufacturing method according to claim 5, wherein a digital support structure (103) is added to the digital dental object (100-1) with the rotated spatial orientation based on the orientation of the reference object (100-R).

7. The manufacturing method according to claim 6, wherein the reference object (100-R) specifies which areas can be provided with a support structure (103).

8. The manufacturing method according to any one of the preceding claims, wherein the dental object (100-2) is manufactured by means of a subtractive manufacturing method.

9. The manufacturing method according to claim 8, wherein a digital holding structure (105) is added to the digital dental object (100-1) with the rotated spatial orientation based on the orientation of the reference object (100-R).

10. The manufacturing method according to any one of the preceding claims, wherein the digital reference object (100-R) is retrievable from a database (107) comprising a plurality of digital reference objects (100-R).

11. The manufacturing method according to claim 9 or 10, wherein the reference object (100-R) specifies which areas can be provided with a holding structure (105).

12. The manufacturing method according to any one of the preceding claims, wherein the digital dental object (100-1) comprises data about an indication.

13. The manufacturing method according to claim 12, wherein the digital reference object (100-1) is retrievable or assignable from a database (107) based on the data about the indication.

14. A manufacturing system (200) for manufacturing a dental object, comprising a computer program, comprising instructions which, when the computer program is executed by a computer, cause it to execute the method according to any one of claims 1 to 13.