MANUFACTURING PROCESS FOR A DENTAL OBJECT

Description

[0001] The present invention relates to a manufacturing method for a dental object and a dendritic base structure for constructing a dental object by a three-dimensional printing method.

[0002] In three-dimensional printing processes, the object to be produced must be connected to the printer in a suitable manner. This connection usually takes place on the printer's build platform. The adhesion at the interface between the build platform and the object ensures the object's positional accuracy within the build space during the subsequent printing process.

[0003] However, in stereolithography, there are processes in which the object is subjected to forces during production, which are also transferred to the interface between the build platform and the object. For a fast and reliable process, these forces must be kept as low as possible. Current base structures are disadvantageous in ensuring the adhesion of the object to a build platform with regard to the fluid-specific process forces. A polymerized surface of a base structure simultaneously represents an adhesion-promoting surface but also a barrier to the free flow of material. Document US 2019 / 263070 A1 discloses a 3D printing process for a dental object on a lattice structure.

[0004] It is the technical object of the invention to ensure an efficient transmission of forces from a dental object to a build platform of a printer and to enable an efficient removal of uncured manufacturing material.

[0005] This technical problem is solved by subject matter according to independent claims 1 and 13. Technically advantageous embodiments of the invention are the subject matter of the dependent claims.

[0006] According to a first aspect, the technical problem is solved by a manufacturing method for a dental object, comprising the steps of generating a dendritic base structure on a build platform; and building the dental object on the dendritic base structure using a three-dimensional printing process. The dendritic base structure achieves the technical advantage that forces can be efficiently transferred from the dental object to the build platform and damage to the structures built thereon is prevented. The dendritic base structure ensures a connection between the build platform and other support structures, while achieving good adhesion, good material flow, and low process forces. After partial curing of the manufacturing material, uncured manufacturing material is located between the branches and twigs as well as the remaining structures of the base structure.This fabrication material should be removed during the subsequent manufacturing process. The open dendritic base structure provides the technical advantage that the uncured, liquid fabrication material can quickly drain from the interstices, accelerating the fabrication of the dental object. Good material flow is characterized by faster pressure equalization when separating and moving the build platform over the inflowing or extruding fabrication material along the polymerized structure.

[0007] In the manufacturing process, the dendritic base structure has a main structure from which branches extend outward. The branches can extend outward in a star shape. This achieves the technical advantage of achieving good force distribution in all directions, for example.

[0008] In a technically advantageous embodiment of the manufacturing process, the main structure of the dendritic base structure lies beneath the geometric center of the dental object. This achieves the technical advantage, for example, that forces from the dental object are evenly distributed across the base structure.

[0009] In a further technically advantageous embodiment of the manufacturing process, a branch of the dendritic base structure is formed with a smaller width than a branch of the dendritic base structure. This achieves the technical advantage, for example, of transmitting forces to outer regions with minimal material expenditure.

[0010] In another technically advantageous embodiment of the manufacturing process, support structures for the dental object are created on the base structure. This achieves the technical advantage, for example, of efficiently transferring forces from the dental object to the base structure.

[0011] In a further technically advantageous embodiment of the manufacturing method, at least one support structure is formed beyond the dendritic base structure. This achieves the technical advantage, for example, of being able to produce dental objects with a large span with minimal material expenditure.

[0012] In another technically advantageous embodiment of the manufacturing process, the dendritic base structure is mirror-symmetrical, rotationally symmetrical, or asymmetrical. An asymmetrical base structure can be optimally adapted to the dental object. Free-form dental objects generally result in asymmetrical base structures. This provides the technical advantage of achieving uniform force transmission, for example.

[0013] In another technically advantageous embodiment of the manufacturing process, the main structure of the dendritic base structure is arranged below the center of gravity of the dental object to be constructed. This achieves the technical advantage, for example, of allowing the dental object to be supported evenly.

[0014] In another technically advantageous embodiment of the manufacturing process, the center of gravity of the dental object is supported by a support structure on the main structure of the dendritic base structure. This achieves the technical advantage of further improving the stability of the structure.

[0015] In another technically advantageous embodiment of the manufacturing process, a dendritic support structure is constructed on the dendritic base structure. This achieves the technical advantage, for example, that the support structure can efficiently transfer forces to the base structure.

[0016] In another technically advantageous embodiment of the manufacturing process, the local width of the dendritic base structure is designed to withstand the locally occurring forces from the dental object. This achieves the technical advantage, for example, that the dendritic base structure can transfer forces to the build platform with minimal material usage.

[0017] In another technically advantageous embodiment of the manufacturing process, the dendritic base structure is constructed in layers. This achieves the technical advantage, for example, that the dendritic base structure can be easily manufactured to a desired thickness.

[0018] In a further technically advantageous embodiment of the manufacturing method, the height of the dendritic base structure increases toward the main structure of the dendritic base structure. The lowest parts of the base structure have a height corresponding to the number of cured layers. An increase in height from the outside to the inside can be, for example, 3 (branch) to 6 (branches) to 9 (main structure), or 3 (branch) to 10 (branch) to 20 (main structure). This achieves the technical advantage, for example, that the mechanical strength of the dendritic base structure is adapted to the forces occurring, and material flow is further facilitated.

[0019] In another technically advantageous embodiment of the manufacturing process, several dendritic base structures are created on the build platform. This achieves the technical advantage, for example, of being able to support the dental object over a large width or span.

[0020] According to a second aspect, the technical problem is solved by a dendritic base structure for constructing a dental object using a three-dimensional printing process. This achieves the same technical advantage as the manufacturing process according to the first aspect.

[0021] According to a third aspect which is not part of the invention, a dental object is produced by a manufacturing method according to the first aspect.

[0022] Exemplary embodiments of the description are illustrated in the drawings and are described in more detail below. They show: Fig. 1A and 1B: Top views of different dendritic base structures; Fig. 2A and 2B: Top views of different dendritic base structures; Fig. 3: A perspective view of a dental object that has been built on the base structure; Fig. 4: A cross-sectional view through a dental object during production; Fig. 5: Further cross-sectional views through an angled dental object during production; Fig. 6: A view of an annular dental object during production; and Fig. 7: A cross-sectional view through an angled dental object during production; Fig. 8: A cylindrical dental object with a dendritic base structure; and Fig. 9: Another cylindrical dental object with a dendritic base structure.

[0023] Fig. 1A und 1B show top views of different dendritic base structures 101. The dendritic base structures 101 are created by the first layers of a build order for a three-dimensional dental object 100 in a three-dimensional printing process. The dendritic base structures 101 can be created by a computer-aided calculation process with corresponding calculation rules on a build platform 103 of the printer.

[0024] A dendritic base structure 101 has a flat main structure 105, from which branches extend outward. The mutual distance between the branches can increase toward the outside. The width of the branches decreases toward the outside.

[0025] The dendritic base structure 101 can comprise branches 107 as extensions and twigs 109 as further extensions. A twig 109 branches off from a branch 107. This branch 109 can then, in turn, form a new branch for another branch. Fig. 1A shows a base structure 101 with branches 107 and twigs 109. Support structures 111-1, 111-2, and 111-3 with a geometry corresponding to the force-transmitting function are arranged on this base structure 101. The support structures 111-1, 111-2, and 111-3 support the dental object 100 on the base structure 101. To this end, they establish a mechanical connection between the base structure 101 and the dental object 100. The support structures 111-1, 111-2, and 111-3 can be attached to the dental object 100 with hemispherical or cylindrical structures (support heads).

[0026] Fig. 1B shows an embodiment with a geometrically reduced base structure 101. The extensions can connect the base of two or more support structures 111-1, 111-2 and 111-3 or bridge the shortest path to neighboring dendrites.

[0027] Fig. 2A und 2B show further views of different dendritic base structures 101. Fig. 2A shows a constriction 131 between two branches. The uncured production material can only flow through this constriction 131 with inhibited material flow. Fig. 2B shows an optimized base structure 101. Points 129-1, 129-2, and 129-3 are the center of base structure 101 at different times. Base structure 101 is selectively opened and follows a projection of the line of the layer-specific centroids. The multicenters of base structure 101 each have a suitable wall thickness.

[0028] Fig. 3 shows a perspective view of the dental object 100, which is constructed on the dendritic base structure 101. The dental object 100 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 can be any object in the dental field that is to be produced using a three-dimensional printing process.

[0029] During the production of the dental object 100, the dendritic base structure 101 is first built layer by layer on the flat build platform 103 of the printer. For example, with a number of ten layers with a height of 50 μm, a total dendritic base structure 101 with a height of 500 μm is created before a free flow of the liquid production material through the higher-level support structures 111 can take place.

[0030] The dendritic base structure 101 serves to transfer forces during production to the build platform 103. The dendritic base structure 101 adheres to the build platform 103 and supports the dental object 100 during the printing process. As an adhesive surface on the build platform 103, the dendritic base structure 101 is dimensioned precisely large enough to withstand the forces of the print job while discharging the liquid production material from the base structure 101 with minimal counterforces.

[0031] After the dendritic base structure 101 has been fabricated on the build platform 103, the columnar or post-shaped support structures 111 for the dental object 100 are fabricated layer by layer. Generally, the support structures 111 serve to further transmit force and stiffen the object. These follow the rules of process- and material-dependent construction options, such as a distance to span open spaces or to support spatial minima.

[0032] The support structures 111 support the dental object 100 to be produced on the dendritic base structure 101 and transfer forces occurring from the dental object 100 to the dendritic base structure 101. The support structures 111 connected to the base structure 101 are provided, for example, at locations to support local minima of the dental object 100. The dental object 100 is then produced layer by layer on the columnar support structures 111 using the printing process.

[0033] Fig. 4 shows a cross-sectional view through a dental object 100 during manufacturing. The angle of the center of gravity is perpendicular to the build platform 103. Due to the separation movement of the exposure plane 123 along the vertical axis 119 in the direction of the arrow, the dendritic base structure 101 is also symmetrical in this direction.

[0034] The entire structure, including the dendritic base structure 101, the support structures 111 and the dental object 100, is constructed using a stereolithography process in which the manufacturing material is cured layer by layer by projected light patterns in an exposure plane 123.

[0035] After each step of curing a layer 113, the exposure plane 123 is separated in a separating movement and shifted slightly so that liquid manufacturing material can again penetrate and be cured in the next layer 113 at the exposure plane 123. This creates a separation plane 115 in which the built-up dental object 100 separates from the exposure plane 123. In the first build phase, the separation forces are mainly dominated by the proximity of the build platform 103 to the exposure plane 123.

[0036] In the Fig. 4 The dental object 100 is built layer by layer from bottom to top. The exposure plane 123 is therefore located on top of the dental object 100 and is gradually shifted upwards (bottom-up). However, the process can also be performed in the opposite orientation, so that the dental object 100 is built layer by layer from top to bottom. In this case, the exposure plane 123 is located on the underside of the dental object 100 and is gradually shifted upwards (top-down).

[0037] The separation forces between the exposure plane 123 and the cured layer 113 are lower the smaller the exposure surface is and the easier it is for the liquid manufacturing material to flow freely. The same applies to the delivery process, where a small cross-sectional area generates a low counterforce. A favorable geometry of the dental object 100 creates lower flow resistance of the liquid manufacturing material, which is displaced to bring the specific surface into the intended position. Within the first layers 113, the separation forces correlate with the size of the full-surface build platform 103, which has no pressure-relieving channels or structures.

[0038] The dendritic base structure 101 does not have to connect all support structures 111 to the dental object 100. Individual support structures 111 can also be freely arranged next to the dendritic base structure 101 and connected to the build platform 103. These are completely surrounded by liquid manufacturing material if this is advantageous due to the geometric conditions of the dental object 100 to be manufactured.

[0039] The dendritic base structure 101, characterized by the wide spacing between the branches 107 and twigs 109, promotes sufficient flow of the uncured manufacturing material. After curing, uncured liquid manufacturing material remains between the branches 107 and twigs 109 and the remaining structures. This manufacturing material should be removed during the subsequent manufacturing process. The open dendritic base structure provides the technical advantage that the uncured, liquid manufacturing material can quickly flow out of the gaps. This improves the manufacturing process.

[0040] In addition, a short flow path of the liquid manufacturing material into the vicinity of the intended exposure area in the exposure plane 123 is achieved. The local width or height of the branches 107 and twigs 109 of the dendritic base structure 101 is designed for the locally expected forces, which vary depending on the separation position on the build platform 103 and in relation to other dental objects 100, the centers of gravity, or center of gravity shifts of the dental objects 100.

[0041] The dendritic base structure 101 has a main structure 105, such as a center, from which the star-shaped branches 107 extend outward. The number of branches 107 and twigs 109 of the base structure 101 depends on the supporting structure, which is based on the geometry of the dental object.

[0042] The main structure 105 of the dendritic base structure 101 can be located in the geometric center of the formed support structure 111. The lengths of the branches 107 and twigs 109 of the dendritic base structure 101 adapt accordingly in this case. This applies, for example, to dental objects 100 with a large span whose center of mass lies outside the dental object 100, such as ring-shaped or horseshoe-shaped dental objects 100.

[0043] Fig. 5 shows another cross-sectional view through an inclined dental object 100 during production in two orientations. Since the dental object 100 to be produced is not symmetrical in the vertical direction when projected onto the build platform 103, a shift in the center of gravity occurs with each additional layer 113 during the layer-by-layer production of the dental object 100.

[0044] The main structure 105 of the base structure 101 can follow this center of gravity shift, so that during the construction of the dental object 100, a corresponding adhesion surface or holding point exists on the build platform 103 for each newly created center of gravity in the vertical direction. The direction of the main structure 105 results from the sum of all centers of gravity of the respective individual layers.

[0045] In a first embodiment of the dental object (left), the main structure 105 of the dendritic base structure 101 extends horizontally. The length of the main structure 105 is calculated from the force vector acting at the interface under the given current separation conditions. If the force vector acting at the force application point changes during the separation process, this also changes the length of the main structure 105.

[0046] The force transmission between the dental object 100 and the dendritic base structure 101 is carried out by the support structures 111. The design of the support structures 111 follows the same rules, so that all support structures 111 are supported as individual objects against force attacks.

[0047] In a second embodiment of the dental object (right), the dental object 100 is constructed symmetrically in the vertical direction. In this case, the dental object 100 can be constructed on a dendritic base structure that extends below the dental object 100.

[0048] Fig. 6 shows another view of a ring-shaped dental object 100 with multiple dendritic base structures 101 during production. The dendritic base structures 101 are arranged along the lower ring surface of the dental object 100 and are formed in various embodiments of dendrite-like branches. The dendritic base structure 101 is divided into multiple base structures 101 for the geometry of the dental object 100.

[0049] The dental object 100 can be divided into a plurality of segments, for example, 360 segments, which result from a family of planes around the normal vector in the z-direction of the center of mass of the dental object 100. The main structures 105 result from the sum of all centers of gravity of the individual segments—comparable to the neutral fiber of the dental object 100. The secondary rays follow the center of gravity shift of the dental object or dental object segment. Such ring-shaped dental objects 100 have an interrupted main structure 105.

[0050] There may also be multiple main structures 105 if this represents the most effective connection for the dental object 100 to be manufactured, for example, in the case of a bone-shaped dental object 100 with a main structure 105 at each end. This can further increase the material flow, since the subdivision with multiple main structures 105 creates wider channels that facilitate the material flow.

[0051] Fig. 7 shows a cross-sectional view through an angled dental object 100 during production. The laterally offset construction creates a dental object 100 with a center of gravity that varies across its height. Even if an open structure with sufficient width is present, the height of a pressure equalization opening is only a fraction of the width in this early phase of the printing process.

[0052] Fig. 8 shows a cylindrical dental object 100 with a dendritic base structure 101 in a non-z-symmetric orientation. The angles α and β are the local angles of the object surface to the base plane. Line 125 represents the sum of all layer-specific area centroids. The times t 1 , t 2 , t 3 , and t 4 are consecutive times within the layered construction process. At time t 1 , t 2 , point 129-1 is the center of the base structure 101; at time t 2 < t < t 3 , point 129-2 is the center of the base structure 101; and at time t 3 , t 4 , point 129-3 is the center of the base structure 101.

[0053] The angle of inclination of the rotation axis of the dental object 100 is 45° to the build platform 103. The angle of inclination of a surface or partial surface relative to the plane of the build platform 103 determines whether the base structure 101 is self-supporting at the corresponding location or supported by a support structure 111. If, for example, the angle is below a self-supporting angle, support structures 111 are placed and connected to the build platform 103 via the base structure 101.

[0054] Layer information is used for additive manufacturing. Each individual layer has a centroid. During three-dimensional construction, the current centroid is located at any time t during the build process. The sum of all layer-specific centroids results in a line 125 within the dental object 100.

[0055] Depending on the dental object 100, the line 125 of the centroid can lie within the object, such as in the case of a cylinder. The line 125 can also lie partially outside the dental object 100, such as in the case of a cylindrical ring resting on the build platform 103. However, the line 125 can also lie completely within the dental object 100, such as in the case of a cylindrical ring resting on the build platform 103.

[0056] The base structure 101 comprises at least one main structure 105. Further branches 107 or twigs 109 are generated on an object-specific basis. The main structure 105 comprises an area of ​​the two-dimensional projection of the layer-specific surface centroid line onto the plane of the build platform 103. The branches 107 or twigs 109 support the main axes emanating from the base structure 101, taking into account the requirements for an adhesion surface and flow behavior.

[0057] Preferably, areas of the first or first object surfaces, ie local minima, are supported.

[0058] Fig. 9 shows a cylindrical dental object with a dendritic base structure 101 with a non-z-symmetric orientation. Line 127 represents the path of the resulting volume center of gravity through the layered structure.

[0059] The angle of inclination of the rotation axis of the dental object 100 differs from 45° to the build platform 103. The angle α of one side of the dental object 100 is below the self-support angle, and the angle β is above the self-support angle. Therefore, support structures 111 are created on the left side, while no support structures 111 are required on the right side. The resulting base structure 101 is oriented toward the projection of the line of the volume centers of gravity 127.

[0060] Similar to the course of line 125 of all surface centroids, line 127 of the volume centroid can also lie inside or outside the dental object 100. The surface centroid can always lie inside the dental object 100, and the volume centroid can always lie outside the dental object 100, for example, in the case of a spiral standing on the build platform 103. All geometric information can be used to generate an optimized base structure 101.

[0061] At time t 3 the projection of the area center of gravity may lie outside the base structure 101 ( Fig. 9 - right). The base structure 101 is extended by a distance a 2 - a to reduce the moment of force on the adhesion surface caused by the geometry-related center of gravity shift.

[0062] The scope of the present invention is given by the claims LIST OF REFERENCE SYMBOLS

[0063] 100Dental object 101Dendritic base structure 103Building platform 105Main structure 107Branch 109Twig 111Support structure 113Layers 115Parting plane 117Shear force 119Vertical axis 121Horizontal movement 123Exposure plane 125Line of centroids 127Line of volume centroids 129Point 131Bottleneck

Claims

1. A manufacturing method for a dental object (100), comprising the steps of: - creating a flat dendritic base structure (101) on a build platform (103), wherein the dendritic base structure (101) comprises a main structure (105) from which extensions (109, 107) extend outwards, wherein the widths of the extensions decrease towards the outside; and - building the dental object (100) on the dendritic base structure (101) by a three-dimensional printing process.

2. The manufacturing method according to claim 1, wherein the main structure (105) of the dendritic base structure (101) is located below the geometric center of the dental object (100).

3. The manufacturing method according to any one of the preceding claims, wherein a twig (109) of the dendritic base structure (101) is formed with a smaller width than a branch (107) of the dendritic base structure (101).

4. The manufacturing method according to any one of the preceding claims, wherein support structures (111) for the dental object (100) are created on the base structure (101) .

5. The manufacturing method according to any one of the preceding claims, wherein at least one support structure (111) is formed beyond the dendritic base structure (101) .

6. The manufacturing method according to any one of the preceding claims, wherein the dendritic base structure (101) is mirror symmetric, rotationally symmetric or asymmetric.

7. The manufacturing method according to any one of the preceding claims, wherein the main structure (105) of the dendritic base structure (101) is arranged below the center of gravity of the dental object (100) to be built.

8. The manufacturing method according to claim 7, wherein the center of gravity of the dental object (100) is supported by a support structure (111) on the main structure (105) of the dendritic base structure (101).

9. The manufacturing method according to any one of the preceding claims, wherein a dendritic support structure (111) is built on the dendritic base structure (101).

10. The manufacturing method according to any one of the preceding claims, wherein a local width of the dendritic base structure (101) is adapted to the locally occurring forces by the dental object (100).

11. The manufacturing method according to any one of the preceding claims, wherein the dendritic base structure (101) is built up in layers (113).

12. The manufacturing method according to any one of the preceding claims, wherein a height of the dendritic base structure (101) increases toward the main structure (105) of the dendritic base structure (101).

13. A flat dendritic base structure (101) for building a dental object (100) by a three-dimensional printing process, wherein the dendritic base structure (101) comprises a main structure (105) from which extensions (109, 107) extend outwards and wherein the widths of the extensions decrease towards the outside.