Method and system for designing a dental appliance

Abstract

One aspect of the present disclosure is to provide a computer-implemented method that can perform volumetric operations at faster speed and lower memory requirements. In one embodiment, this efficiency is achieved by representing a digital 3D volumetric space of digital 3D dental data only in part with subgrids. It advantageously avoids calculations performed in a partial region of the digital 3D volumetric space because execution time or memory requirements, or both, may be small. According to the invention, the operation is carried out on the sub-grid level instead of the single cell level, so that the efficiency can be further improved.

Description

Technical Field

[0001] The present disclosure relates to performing volumetric operations at faster speeds and with lower memory requirements. Specifically, the present disclosure relates to a method, system, and computer-readable medium for performing volumetric operations corresponding to digital 3D data in a digital 3D volume space, such as when digitally designing a dental appliance. Background Art

[0002] Volumetric operations on digital 3D data are used in many industrial fields and in different applications. For example, volumetric operations can be used to generate surfaces from point clouds representing 3D shapes or objects, to generate modified surfaces from existing surfaces by morphing, such as by copying, offsetting, smoothing, distorting, etc.

[0003] Volumetric operations such as the marching cubes algorithm provide a means of converting a signed distance field into a 3D polygonal mesh. The algorithm samples the signed distance field on a high-resolution grid and creates triangles within the grid cells. Since the spatial detail of the resulting 3D mesh is determined by the grid resolution, the marching cubes algorithm typically requires a lot of storage and processing time. Assuming that the mesh to be reconstructed is contained in a bounding box of feature length L, and the desired level of detail is d, the number of grid cells in one dimension is and the total number of grid cells is therefore In many applications, It may be on the order of 500 or more.

[0004] Variants of the marching cubes algorithm have been proposed to reduce processing time and storage requirements. For example, parallel computation is performed on a graphics processing unit (GPU) and an adaptive grid represented by an octree structure is used, where large grid cells are used in areas with fewer surface points and small grid cells are used in areas with a higher density of surface points. However, this variant can only create triangles at the leaf nodes of the tree structure. There is currently no reasonable extension of this principle to volume operations. Other proposed octree-based algorithms may include offset operations and involve tiling the volume of interest (e.g., a digital 3D model). However, even such algorithms require that the offset surface is represented by a narrow set of geometric primitives such as spheres and cylinders.

[0005] In the dental field, there are several treatment methods involving the design and construction of dental appliances, such as the restoration of a single tooth, part of a tooth, or all teeth on a jaw. Computer-aided design (CAD) of such appliances involves calculations that are preferably performed in a digital 3D volume space. At the same time, the spatial resolution of the grid provided by a dental 3D scanner is much smaller than the size of the teeth, especially the size of the jaw. Therefore, volumetric calculations for designing restorations and appliances in dental CAD are highly desirable, but the calculations known in the art are very computationally demanding.

[0006] What is desired is an alternative method for performing volumetric operations corresponding to digital 3D data in a digital 3D volume space, for example, in digitally designing dental appliances, which method can overcome at least some of the above-mentioned limitations. Summary of the invention

[0007] One aspect of the present disclosure is to provide a computer-implemented method that can perform volumetric operations at a faster speed and with lower memory requirements. In one embodiment, this efficiency is achieved by only partially representing the digital 3D volume space of the digital 3D dental data with sub-grids. This advantageously avoids calculations performed in partial areas of the digital 3D volume space because the execution time or memory requirements or both can be smaller. The present disclosure can further improve efficiency by performing operations at the sub-grid level rather than the individual cell level.

[0008] The disclosed method can be particularly suitable for deformation operations in digital 3D volume space, such as smoothing or occlusion operations, for example, digitally filling in the undercut area of ​​a tooth. This makes the disclosed method particularly suitable for computer-aided design of dental appliances, especially for dental appliances that are much larger than features on human teeth.

[0009] According to one aspect, a computer-implemented method for digitally designing a dental appliance is disclosed. The method includes: receiving digital 3D dental data in a digital 3D volume space; calculating at least two signed distances for each of a plurality of subgrids relative to the received digital 3D dental data, wherein each subgrid includes a plurality of cells; identifying a subgrid group from the plurality of subgrids, such that the identified subgrid group collectively corresponds to only a portion of a bounding box that includes the received digital 3D dental data. The identification of the subgrid group is based on the calculated at least two signed distances. Finally, digitally designing a dental appliance based on the identified subgrid group.

[0010] According to one aspect, a computer-implemented method for digitally designing a dental appliance is disclosed. The method includes: receiving digital 3D dental data in a digital 3D volume space; calculating at least two signed distances of each of a plurality of sub-grids relative to the received digital 3D dental data, each sub-grid including a plurality of cells; identifying a sub-grid group from the plurality of sub-grids based on the calculated at least two signed distances, such that the identified sub-grid group collectively corresponds only to the received digital 3D dental data; and digitally designing a dental appliance based on the identified sub-grid group.

[0011] According to one aspect, a computer-implemented method for digitally designing a dental appliance is disclosed. The method includes: receiving digital 3D dental data in a digital 3D volume space; calculating at least two signed distances for each of a plurality of sub-grids relative to the received digital 3D dental data, wherein each sub-grid includes a plurality of cells; ignoring a plurality of sub-grids of the plurality of sub-grids that do not include the 3D digital dental data based on the calculated at least two signed distances; and digitally designing a dental appliance based on a group of sub-grids of the plurality of sub-grids that do not form part of the ignored plurality of sub-grids.

[0012] According to one aspect, a computer-implemented method for digitally designing a dental appliance is disclosed. The method includes: receiving digital 3D dental data in a digital 3D volume space; calculating at least two signed distances for each of a plurality of sub-grids relative to the received digital 3D dental data, each sub-grid including a plurality of cells; ignoring a cluster of sub-grids from a sub-grid corresponding to a bounding box containing the 3D digital dental data based on the calculated at least two signed distances, such that the cluster of sub-grids does not contain the 3D digital dental data; and digitally designing a dental appliance based on a group of sub-grids in the plurality of sub-grids that do not form part of the ignored plurality of sub-grids.

[0013] According to one aspect, a computer-implemented method for digitally designing a dental appliance is disclosed. The method includes: receiving digital 3D dental data in a digital 3D volume space; calculating at least two signed distances of each of a plurality of sub-grids relative to the received digital 3D dental data; identifying a sub-grid group from the plurality of sub-grids based on the calculated at least two signed distances, such that the identified sub-grid group collectively corresponds to the received digital 3D dental data; and finally, digitally designing a dental appliance based on the identified group of sub-grids.

[0014] Dental appliances may include appliances configured to provide restorative treatment (such as a restoration), orthodontic treatment (such as a clear aligner), or preventive effects (such as a night guard). Thus, dental appliances may also include any of a splint, a retainer, a partial denture. The dental appliance may include a first surface, an outer surface, which is arranged to be adjacent to the facial surface of the teeth when the user wears the dental appliance. The dental appliance may include a second surface, an inner surface, which is arranged to be adjacent to the lingual surface of the teeth when the user wears the dental appliance.

[0015] In some examples, an identified submesh in the identified submesh group may include digital 3D dental data corresponding to both a first surface and a second surface of a dental appliance model, in which case it is important to assign the identified submesh to the correct surface, which may be the surface having the shortest signed distance to the identified submesh among the multiple submeshes.

[0016] The computer-implemented method may include assigning the identified sub-mesh group to a first surface or a second surface of the digital 3D dental data based on at least two signed distances. The at least two signed distances may include: a first signed distance determined between a first point of a sub-mesh in the identified sub-mesh group and the first surface; and a second signed distance determined between a second point of a sub-mesh in the identified sub-mesh group and the second surface. The shortest of the first signed distance and the second signed distance determines whether the identified sub-mesh is assigned to the first surface or the second surface of the digital 3D dental data.

[0017] The digital 3D dental data represents at least a portion of at least one tooth on a jaw. The digital 3D dental data of the patient's mouth may include one or more of surface 3D data obtained from an oral scanner and / or sub-surface 3D data such as obtained from a cone beam computed tomography (CBCT) scanner. The digital 3D dental data may be represented in a variety of ways, for example, as a point cloud or surface information represented in a 3D polygonal mesh or any other form suitable for calculating a signed distance associated with a sub-mesh.

[0018] Receiving the digital 3D dental data may include importing (usually in response to a user selection) the digital 3D dental data from a database. The digital 3D dental data may be acquired directly by optically scanning the patient's oral cavity. Optically scanning the patient's oral cavity may include directly scanning the patient's oral cavity using an oral scanner (such as the TRIOS oral scanner of 3Shape AS of Denmark) or a dental X-ray scanner. The above-mentioned dental scanners may use different imaging techniques, such as focused scanning, time-of-flight, stereo imaging, confocal scanning, triangulation, cone beam computed tomography (CBCT) technology. Alternatively, optically scanning the patient's oral cavity may also include indirectly scanning the patient's oral cavity by scanning a negative impression of the patient's teeth or a physical tooth model made based on a negative impression of the patient's teeth. The physical tooth model may be scanned using a desktop dental scanner (such as the E-series scanner of 3Shape AS of Denmark).

[0019] The digital 3D volume space can be understood as a grid, in which digital 3D dental data is received, and dental appliances are digitally designed. Multiple subgrids are defined in the digital 3D volume space so that the digital 3D volume space includes multiple subgrids. This can be achieved by dividing the digital 3D volume space into multiple subgrids, wherein the sizes of the multiple subgrids can be equal and have the same shape. Each subgrid in the multiple subgrids can include multiple cells, and the sizes of these cells can be equal. Cells of equal size can generally include the same shape and size. The digital 3D volume space is divided into subgrids or cells in each subgrid can be based on one or more predefined values, and the predefined values ​​are generally defined before receiving the digital 3D dental data in the digital 3D volume space. This division or shape and size of multiple subgrids and / or multiple cells can even be a function of the dental appliances to be digitally designed, that is, different predefined values ​​can be used for different dental appliances. Different values ​​can be automatically selected based on the instructions of the dental appliances imported into the digital 3D volume space.

[0020] Each sub-grid in the identified group of sub-grids may include a plurality of cells, wherein at least two signed cell distances are determined for each cell in the plurality of cells, and a cell group is identified based on the at least two signed cell distances, and wherein a volume operation is performed on each identified cell in the cell group.

[0021] How to determine the signed cell distance for each cell in the plurality of cells is similar to how to determine the signed distance for each subgrid in the plurality of subgrids. The identified group of cells may be based on cell selection criteria, similar to the selection of the identified subgrids.

[0022] The subgrids include a certain shape. In one embodiment, the shape is a cube shape. This can allow the use of algorithms such as the marching cubes algorithm. However, in another embodiment, the shape is a non-cubic shape, such as a cuboid, tetrahedron, or other shape, which may allow the use of a variant of the marching cubes algorithm. In some embodiments, all subgrids in the plurality of subgrids may have the same size and cells of the same size, i.e., the same number of cells in the corresponding dimensions. In some embodiments, the subgrids have the same number of cells in all three dimensions. In some such embodiments, the cells of such subgrids are cubes, so that the subgrids themselves are also cubes.

[0023] By applying multiple cells to the computer-implemented method, volumetric operations can be performed faster and with reduced memory requirements.

[0024] Each subgrid in the plurality of subgrids may include a shape having a plurality of corner points. Additionally, the identified subgrid group may include a plurality of edge points along one or more edges connecting a pair of corner points in the plurality of corner points. In another embodiment, each subgrid in the plurality of subgrids includes a plurality of edge points along one or more edges connecting a pair of corner points in the plurality of corner points. Typically, a plurality of edge points are evenly distributed along the edge of the subgrid. The number of corner points and / or edge points of each subgrid may be flexibly selected to best match the capabilities of a central processing unit (CPU) or a graphics processing unit (GPU) of a computer. Powers of 2 generally produce the highest computing performance. For example, a cubic subgrid with grid points of 8x8x8, or 16x16x16, etc. may be a good choice.

[0025] In one embodiment, each of the plurality of sub-meshes comprises a shape having a plurality of corner points or vertices. Additionally or alternatively, the selected group of sub-meshes comprises a plurality of edge points along one or more edges connecting a pair of corner points in the plurality of corner points. In another embodiment, the plurality of sub-meshes comprises a plurality of edge points along one or more edges connecting a pair of corner points in the plurality of corner points.

[0026] In different embodiments, the corner points and / or edge points may correspond to one or more cells contained in the sub-grid. In other words, the corner points and / or edge points of the sub-grid may coincide with the corner points of one or more cells contained in the sub-grid.

[0027] In one embodiment, a plurality of edge points are uniformly distributed along the edge of the sub-grid. This forms a first distance between a point and a first adjacent point, and a second distance between the point and a second adjacent point, wherein the point, the first adjacent point, and the second adjacent point are positioned along the edge. In another embodiment, a plurality of edge points are non-uniformly distributed along the edge of the sub-grid. This includes at least one adjacent point pair being positioned at a distance along an edge, which is different from another distance between another adjacent point pair positioned along the edge. In either embodiment, it is generally preferred that adjacent grids have overlapping corner points and / or edge points so as to achieve continuity and computational efficiency in the generation of the surface when applying the surface construction algorithm. Alternatively, non-overlapping corner points and / or edge points between adjacent grids can also be used for surface construction. However, further interpolation is required between the surfaces generated in each adjacent grid, thereby reducing the desired computational efficiency.

[0028] In one embodiment, the corner points of adjacent sub-grids of equal size share the same 3D coordinates, so that the edges between the corner points of adjacent sub-grids are coincident. If there is no such coincidence, additional interpolation calculations are required, resulting in a loss of computational efficiency.

[0029] Therefore, in one embodiment, a volume such as a digital 3D volume space is represented by multiple subgrids. Each subgrid includes cells, i.e., grid cells. The grid cells in all subgrids have uniform size and shape. No subgrid covers a portion of the volume that is not of interest. In other words, subgrids that are not of interest will be ignored from the volume, or subgrids of interest will be selected from the volume. Therefore, the volume covered by multiple subgrids is typically smaller than the volume covered by a single large grid with cells of uniform size, which is well known in the art of surface construction algorithms (such as the marching cube algorithm).

[0030] In one embodiment, the method includes placing sub-grids in the digital 3D volume space. Such placing may include selecting sub-grids, such as selecting a group of sub-grids, which at least partially (such as completely) cover the digital 3D dental data or are required to perform a volumetric operation. The sub-grids required to perform a volumetric operation may include sub-grids covering the digital 3D dental data in a state different from a state of the received digital 3D dental data, the different state being related to the volumetric operation.

[0031] In one embodiment, whether a sub-grid covers the digital 3D dental data can be determined by calculating the nearest signed distance between a grid point (e.g., a corner point or an edge point) of the sub-grid and the digital 3D dental data. Without loss of generality, it is assumed that a positive distance refers to a grid point that is outside the digital 3D dental data. Therefore, if all grid points along the edge of the sub-grid are positive, the sub-grid is outside the digital 3D dental data. By the above test, intrusion points that are smaller than the length of the grid cell may be ignored, but they are generally not of concern. If all signed distances of the grid are greater than any predefined parameter value (e.g., an expected offset), the candidate sub-grid will be outside the relevant space of the digital 3D volume space required to perform volumetric operations, and therefore there is no need to place such a sub-grid for the purpose of digitally designing dental appliances.

[0032] Each of the plurality of sub-grids may include a shape having at least a first point and at least a second point, and wherein a first signed distance is determined between the first point and the digital 3D dental data, and at least a second signed distance is determined between the at least second point and the digital 3D dental data. The at least two signed distances include the first signed distance and the second signed distance.

[0033] The shape typically includes a plurality of corner points or vertices and one or more edges connecting a pair of corner points among the plurality of corner points. The shape need not be understood as a visible object in the digital 3D volume space, but rather refers to parameters that allow a surface construction algorithm (such as a marching cube algorithm or a variant thereof) to be executed to generate a surface in the digital 3D volume space. Therefore, the shape and any aspect thereof may also be understood in conjunction with corner points and / or edge points, the values ​​of which may be calculated. In addition, corner points and edge points are identified by their corresponding 3D coordinates in the digital 3D volume space.

[0034] The first signed distance may be a minimum distance between the first point and the digital 3D dental data, and the second signed distance may be a minimum distance between the second point and the digital 3D dental data.The plurality of corner points and / or the plurality of edge points include the first point and at least the second point.

[0035] The first point and the at least second point may form part of either or both of the plurality of corner points and / or the plurality of edge points.

[0036] Calculating the signed distance may include using a signed distance function (SDF) that receives coordinates of a point (e.g., a corner point or an edge point) in the digital 3D volume space and returns the shortest distance between the point and the digital 3D dental data. The sign of the return value (i.e., the shortest distance) indicates whether the point is inside or outside the digital 3D dental data. The points for which the signed distance is calculated may include a first point, at least a second point, a corner point, and / or an edge point.

[0037] To illustrate the calculation of signed distance, let's take an example. Consider a sphere centered at the origin. The distance from a point inside the sphere to the origin will be less than the radius of the sphere, the distance from a point on the sphere to the origin will be equal to the radius, and the distance from a point outside the sphere to the origin will be greater than the radius. Therefore, the signed distance function of a sphere centered at the origin and with a radius of 1 is expressed as

[0038]

[0039] For a sub-mesh corner point located at (x=1, y=0, z=0) in the 3D volume space, f(1,0,0)=0 means that the sub-mesh corner point is located on the surface of the sphere. For a sub-mesh corner point located at (x=0, y=0, z=0.5) in the 3D volume space, f(0,0,0.5)=-0.5 means that the sub-mesh corner point is located inside the surface, 0.5 units away from the nearest point on the surface. For a sub-mesh corner point located at (x=0, y=3, z=0) in the 3D volume space, f(0,3,0)=2 means that the sub-mesh corner point is located outside the surface, 2 units away from the nearest point on the surface.

[0040] In one embodiment, calculating the signed distance may include determining the signed distance at a plurality of corner points. In another embodiment, calculating the signed distance may include determining the signed distance at a plurality of edge points located on at least one edge. In another embodiment, calculating the signed distance may include determining the signed distance at a plurality of edge points located on at least one edge and a plurality of corner points.

[0041] In one embodiment, the method may further include determining, based on the calculated signed distance, whether a corner point of the plurality of corner points and / or an edge point of the plurality of edge points is located on a first side or a second side of a surface contained in the digital 3D dental data, or is located on the surface. The method may further include identifying a sub-grid corresponding to the digital 3D dental data based on the position of the plurality of corner points and / or the plurality of edge points relative to the digital 3D dental data. This is possible because the sub-grid includes a plurality of corner points and / or a plurality of edge points for which the signed distance is calculated. If the corner points and / or edge points of the sub-grid are identified as being located within or on the surface of the digital 3D dental data, it is determined that the sub-grid corresponds to the digital 3D dental data.

[0042] In one embodiment, the method may further include determining, based on the calculated signed distance, whether the first point and / or at least the second point is located on a first side, on a second side, or on the surface defined by the digital 3D dental data. The method may further include identifying a sub-grid corresponding to the digital 3D dental data based on the position of the first point and at least the second point relative to the digital 3D dental data. This is possible because the sub-grid includes a first point and at least a second point, for which the signed distance is calculated. If the first point and at least the second point of the sub-grid are identified as being located on a first side, on a second side, or on the surface of the surface determined by the digital 3D dental data, it is determined that the sub-grid corresponds to the digital 3D dental data. If the sub-grid does not include information about the surface corresponding to the digital 3D dental data, the sub-grid does not correspond to the digital 3D dental data.

[0043] The calculated signed distance for each of the plurality of sub-grids may be determined between a first edge point of the plurality of edge points or a first corner point of the plurality of corner points and the digital 3D dental data, and between a second edge point of the plurality of edge points or a second corner point of the plurality of corner points and the digital 3D dental data.

[0044] The at least two calculated signed distances for each of the plurality of sub-grids may be determined between a first corner point of the plurality of corner points and the digital 3D dental data, and between a second corner point of the plurality of corner points and the digital 3D dental data. The digital 3D dental data of the sub-grid may include more than one surface, and in this example, it must be determined which surface is most relevant to the sub-grid.

[0045] Obviously, identifying or ignoring a candidate sub-mesh, i.e. checking a sub-mesh to determine whether it corresponds to a digital 3D dental model or a part of a digital 3D dental model, typically requires checking whether corresponding signed distances at one or more points (e.g. corner points and / or edge points of the candidate sub-mesh) are located on a first side of a surface defined by the digital 3D dental data, on a second side of the surface or on the surface. The first side is opposite to the second side.

[0046] Therefore, in order to identify a sub-mesh corresponding to the digital 3D dental model, a selection criterion may be determined.The selection criterion may include at least one point, such as a corner point and / or an edge point located in or on the surface of the digital 3D dental data.

[0047] The sub-grid group can be identified in different ways. The identification of the sub-grid group can include identifying the sub-grid when at least two signed distances at the first point and the second point meet the selection criteria. Alternatively, the identification of the sub-grid group can include identifying the sub-grid when at least two signed distances at the first corner point and at least the second corner point meet the selection criteria. Alternatively, the identification of the sub-grid group can include identifying the sub-grid when at least two signed distances at the first corner point or the first edge point and at least the second corner point or at least the second edge point meet the selection criteria. The selection criteria can include at least one positive signed distance and at least one negative signed distance. The first point and the at least second point having a positive signed criterion and a negative signed criterion, respectively, indicates that the sub-grid including the first point and the at least second point corresponds to the digital 3D dental data.

[0048] In one embodiment, identifying a sub-grid group includes identifying a sub-grid by causing at least two signed distances of two corner points to meet the selection criteria, respectively. Additionally or alternatively, identifying a sub-grid group includes identifying a sub-grid by causing at least two signed distances of two edge points to meet the selection criteria, respectively. In another embodiment, ignoring a sub-grid cluster includes ignoring a sub-grid in which at least two signed distances of two corner points do not meet the selection criteria. Additionally or alternatively, ignoring a sub-grid cluster also includes ignoring a sub-grid in which at least two signed distances of two edge points do not meet the selection criteria. The number of defined corner points and / or edge points may be more than two.

[0049] In one embodiment, the method further comprises generating a bounding box containing the digital 3D dental data. A bounding box represents a box with a certain measure (usually a minimum measure) within which all information of the digital 3D dental data is contained. Thus, the bounding box defines a closed volume and can also be represented by bounding coordinates that completely surround the digital 3D dental data. The bounding box of the digital 3D dental data can be used as a reference for placing sub-grids. Based on known techniques, the bounding box of digital 3D dental data (such as a 3D polygonal mesh) is easy to calculate.

[0050] In one embodiment, the method further comprises generating a bounding box including the digital 3D dental data, and at least a first group of sub-grids of the plurality of sub-grids located outside the bounding box. The first group of sub-grids may correspond to a new group of sub-grids associated with an extended surface of the first surface or the second surface. The extended surface may be determined by adding an offset value to the digital 3D dental data defining the first surface or the second surface. In another embodiment, the method further comprises generating a bounding box including the digital 3D dental data, and a second group of sub-grids of the plurality of sub-grids partially located inside the bounding box. The second group of sub-grids may correspond to the digital 3D dental data of the first surface or the second surface, i.e., without the extended surface. The first group of sub-grids and the second group of sub-grids may collectively represent a plurality of sub-grids.

[0051] In another embodiment, the digital design of the dental appliance may include performing a volumetric operation based on at least the identified sub-grid group. In one embodiment, the digital design of the dental appliance may include performing a volumetric operation based on the received digital 3D dental data of at least the identified sub-grid group. In one embodiment, the digital design of the dental appliance may include performing a volumetric operation based on at least the identified parameter value of at least the identified sub-grid group.

[0052] In another embodiment, digital design of the dental appliance may include performing a volumetric operation on the received digital 3D dental data and at least the identified sub-mesh group.

[0053] In one embodiment, the volumetric operation provides a surface of the dental appliance to be designed. The surface includes 3D dental appliance data that can be determined based on the volumetric operation of the received digital 3D dental data of the identified sub-mesh group.

[0054] The volumetric operation may provide at least a first surface and / or at least a second surface of the dental appliance.The surface may include 3D dental appliance data determined based on the received digital 3D dental data of the identified sub-mesh group.

[0055] The dental appliance includes a surface that may be curvilinear in shape. A volume may be partially surrounded by the surface, wherein the volume is configured to receive one or more teeth in whole or in part. The dental appliance may include an opening configured to receive one or more teeth, and the one or more teeth are disposed within the volume.

[0056] In order to improve the comfort of wearing dental appliances and make dental appliances easier to wear, an offset can be applied to the design of the dental appliances so that the volume along at least the face to tongue axis of the dental appliances is increased. The face to tongue axis extends between the face and tongue surface of one or more teeth. When the dental appliance is applied to one or more teeth, the increased volume will reduce the friction between the one or more teeth and the dental appliance. In order to obtain the desired effect by applying an offset, the computer-implemented method can also include calculating the extended signed distance of multiple extended sub-grids by adding an offset value to each of the signed distances calculated to the identified sub-grid group. The multiple extended sub-grids can include the digital 3D dental data of the extended identified sub-grid group, and the first volume operation is performed on the extended digital 3D dental data in the multiple extended sub-grids. In addition, the method may further include: determining an extended surface based on the first volume operation, and the extended surface includes extended digital 3D surface data corresponding to a plurality of extended sub-grids; and calculating a compressed signed distance of a plurality of compressed sub-grids by subtracting offset values ​​of the extended signed distances of the plurality of extended sub-grids, wherein the plurality of compressed sub-grids include compressed digital 3D surface data determined based on the extended digital 3D surface data. In addition, the method may further include: performing a second volume operation on the compressed digital 3D surface data in the plurality of compressed sub-grids; setting a compressed surface based on the second volume operation, and the compressed surface includes compressed digital 3D surface data corresponding to the plurality of compressed sub-grids; and setting a surface of the dental appliance based on the compressed surface.

[0057] The first surface and the second surface may include 3D dental appliance data determined based on the received digital 3D dental data of the identified sub-grid group. The dental appliance may include a first surface, i.e., an outer surface, which is close to the facial surface of the teeth when the user wears the dental appliance. The dental appliance may include a second surface, i.e., an inner surface, which is close to the lingual surface of the teeth when the user wears the dental appliance. The lingual surface is closest to the user's tongue. In order to improve wearing comfort and make wearing easier, an offset may be used when designing the dental appliance to increase the volume between the inner surface and the outer surface. Then, the computer-implemented method may include calculating the extended outer signed distance of multiple extended outer sub-grids by adding an outer offset value to each calculated signed distance of the identified sub-grid group. The multiple extended outer sub-grids include the digital 3D dental data of the extended identified sub-grid group. The method may further include calculating an extended inner signed distance of a plurality of extended inner sub-grids by adding an inner offset value to each calculated signed distance of the identified sub-grid group, wherein the plurality of extended inner sub-grids include the digital 3D dental data of the identified sub-grid group. In addition, the method may further include performing a first volumetric operation on the extended digital 3D dental data of the plurality of extended outer sub-grids and the plurality of extended inner sub-grids.

[0058] The method may further include determining an extended outer surface and an extended inner surface based on the first volume operation, wherein the extended outer surface includes extended digital 3D surface data corresponding to the plurality of extended outer sub-grids, and the extended inner surface includes extended digital 3D surface data corresponding to the plurality of extended inner sub-grids.

[0059] The extended outer surface and the extended inner surface can then be compressed to provide a smoothing effect of the extended surface, and the compressed surface can thus produce a dental appliance that best matches the user's teeth and has a smooth surface. The method can also include: calculating the compressed outer signed distances of multiple compressed outer sub-grids by subtracting the outer offset values ​​of the extended outer signed distances of the multiple extended outer sub-grids, wherein the multiple compressed outer sub-grids include compressed digital 3D surface data determined based on the extended outer surface; calculating the compressed inner signed distances of multiple compressed inner sub-grids by subtracting the inner offset values ​​of the extended inner signed distances of the multiple extended inner sub-grids, wherein the multiple compressed inner sub-grids include compressed digital 3D surface data determined based on the extended inner surface. Then, a second volume operation is performed on the compressed digital 3D tooth data of the multiple compressed outer sub-grids and the multiple compressed inner sub-grids. Based on the second volume operation, a compressed outer surface and a compressed inner surface are determined, and the compressed outer surface includes compressed digital 3D surface data corresponding to multiple compressed outer sub-grids, and the compressed inner surface includes compressed digital 3D surface data corresponding to multiple compressed inner sub-grids, and the outer surface and inner surface of the dental appliance are set based on the compressed outer surface and the compressed inner surface, respectively.

[0060] The first surface and the second surface include 3D dental appliance data determined based on the received digital 3D dental data of the identified sub-mesh group.

[0061] In another example, the computer-implemented method may include calculating an extended outer signed distance and an extended inner signed distance of a plurality of sub-meshes by adding an outer offset value and an inner offset value to each calculated signed distance of the identified sub-mesh group. In addition, the method may also include: determining an extended outer surface and an extended inner surface based on the first volume operation and the digital 3D dental data of the identified sub-mesh group, and the extended outer surface and the extended inner surface include the extended digital 3D surface data; and calculating a compressed outer signed distance and a compressed inner signed distance of the plurality of sub-meshes by subtracting the outer offset value and the inner offset value of the extended outer signed distance and the extended inner signed distance, respectively. Additionally, the method may also include: determining a compressed outer surface and a compressed inner surface based on the second volume operation and the extended digital 3D surface data of the extended outer surface and the extended inner surface, respectively; and setting an outer surface and an inner surface of the dental appliance based on the compressed outer surface and the compressed inner surface, respectively.

[0062] To improve the comfort of the dental appliance, the method may further include widening a portion of the dental appliance. The widening may include determining a widening reference point on the dental appliance by determining a maximum width of the dental appliance along a transverse axis extending from a front portion to a rear portion of the dental appliance, wherein the transverse axis is orthogonal to an insertion axis extending from an upper portion to a bottom portion of the dental appliance, and widening a portion of the dental appliance between the widening reference point and the bottom portion of the dental appliance along the transverse axis.

[0063] The widening may be provided to the width of a free space enclosed by the surface of the dental appliance.

[0064] The widening may be provided to the width of the free space between the first surface and the second surface of the dental appliance.

[0065] The sizes of the multiple sub-grids may be determined based on the type of dental appliance to be digitally designed or based on roughness measurements of the patient's teeth.Dental appliances are custom made to be worn by the patient.

[0066] The sizes of the multiple subgrids can be uniform. It is advantageous to define a uniform grid size because the edges created for adjacent grid cells by a surface construction algorithm (such as the marching cubes algorithm or its variants) can match, so the reconstructed surface will be continuous. This is not the case for methods in the art that use different grid cell sizes to speed up calculations or reduce memory requirements. Another advantage of a uniform grid size is that the location of a grid point can be simply represented by a triple of integer indices ijk. Another advantage is that no geometric primitives (such as shapes, boxes, planes, spheres) are required to represent the offset surface.

[0067] The identified plurality of sub-grids include cells having the same shape and the same size.

[0068] The computer-implemented method can be performed by a processor of a dental system. The dental system can include an oral scanner configured to provide digital 3D dental data to the processor. The dental system can include a computer-readable medium configured to store the digital 3D dental data before forwarding it to the processor. The oral scanner can communicate with the processor via a wired or wireless interface. The wireless interface can be based on WIFI and / or Bluetooth. The processor can be arranged in the oral scanner, or in a computer device outside the oral scanner. The computer device can be configured to communicate with a server or a cloud server to remotely store the designed dental appliances. The storage of the designed dental appliances can include the patient's 3D dental appliance data and the patient's personal information. Therefore, the designed dental information can be retrieved from any dental clinic that can access the server or cloud server. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Various aspects of the present disclosure may be best understood from the following detailed description in conjunction with the accompanying drawings. For the sake of clarity, the drawings are schematic and simplified, and only show details that can enhance the understanding of the claims, while omitting other details. In all drawings, the same or corresponding parts use the same reference numerals. The various features of each aspect may be combined with any or all features of the other aspects, respectively. These and other aspects, features and / or technical effects will be apparent from the examples described below and will be explained with reference to these examples:

[0070] Figure 1A , 1B and 1C show a 2D cross-sectional view of a 3D volume space including the dental object 100;

[0071] Figure 2A , 2B , 2C, 2D and 2E show different examples of how to determine at least two signed distances;

[0072] Figure 3A and 3B A bounding box including digital 3D dental data is shown;

[0073] Figure 4 An example of a digitally designed dental appliance is shown;

[0074] Figure 5A , 5B and 5C show an example of a method for smoothing the surface of a dental appliance;

[0075] Fig. 6A , 6B and 6C show an example of a method for designing a dental appliance; and

[0076] Fig. 7A and 7B A cross-sectional view of a widened dental appliance is shown. DETAILED DESCRIPTION

[0077] The detailed description provided below in conjunction with the accompanying drawings is intended as a description of various configurations. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it is apparent to those skilled in the art that these concepts may be implemented without these specific details. Several aspects of the devices, systems, media, programs, and methods are described by various blocks, functional units, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). Depending on the specific application, design limitations, or other reasons, these elements may be implemented using electronic hardware, computer programs, or any combination thereof.

[0078] Electronic hardware may include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. Computer programs should be broadly understood to mean instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or other terms.

[0079] The scanning for providing intraoral scan data may be performed by a dental scanning system, which may include an intraoral scanning device, such as the TRIOS series scanner of 3Shape A / S. The dental scanning system may include wireless functionality such as provided by a wireless network unit. The scanning device may employ scanning principles such as triangulation-based scanning, confocal scanning, focused scanning, ultrasonic scanning, X-ray scanning, stereoscopic vision, motion recovery structure, optical coherence tomography OCT, or any other scanning principle. In one embodiment, the scanning device operates as follows: a pattern is projected and a focal plane is translated along an optical axis of the scanning device, and a plurality of 2D images are captured at different focal plane positions, so that each series of captured 2D images corresponding to each focal plane forms a stack of 2D images. The acquired 2D images are also referred to herein as raw 2D images, where raw (raw) in this context means that the images have not been image processed. The focal plane position is preferably moved along the optical axis of the scanning system so that for a given viewing angle of the object, i.e., for a given arrangement of the scanning system relative to the object, the 2D images captured at a plurality of focal plane positions along the optical axis form a stack of the 2D images (also referred to herein as sub-scans). After moving the scanning device relative to the object or imaging the object at a different viewing angle, a new stack of 2D images may be captured for that viewing angle.The focal plane position may be changed by at least one focusing element, such as moving a focusing lens.

[0080] During the scanning process, the scanning device is usually moved and angled so that at least some of the sub-scan groups overlap at least partially so that they can be stitched in post-processing. The result of stitching is that the digital 3D representation of a surface is larger than the digital 3D representation that can be captured by a single sub-scan, that is, the digital 3D representation is larger than the field of view of the 3D scanning device. Stitching (also called stitching) works as follows: overlapping areas of 3D surfaces in different sub-scans are identified, and the sub-scans are converted to a common coordinate system so that the overlapping areas match, thereby finally generating a digital 3D model. For this purpose, an iterative nearest neighbor point (ICP) algorithm can be used. Another example of a scanning device is a triangulation scanner, in which a time-varying pattern is projected onto a dental object, and a series of images of different pattern configurations are acquired by one or more cameras positioned at a certain angle relative to the projector unit.

[0081] The scanning device includes one or more light projectors configured to generate an illumination pattern to be projected onto a three-dimensional dental object during scanning. The light projector preferably includes a light source, a mask having a spatial pattern, and one or more lenses (such as a collimating lens or a projection lens). The light source can be configured to generate light of a single wavelength or a combination of wavelengths (monochromatic or polychromatic). The wavelength combination can be generated by using a light source configured to generate light containing different wavelengths (such as white light). Alternatively, the light projector can include multiple light sources, such as LEDs, each of which generates light of different wavelengths (such as red light, green light, and blue light), which can be combined to form light containing different wavelengths. Therefore, the light generated by the light source can be defined by a wavelength that defines a specific color, or by a different wavelength range that defines a color combination (such as white light). In one embodiment, the scanning device includes a light source configured to excite a fluorescent material of a tooth to obtain fluorescent data of a dental object. Such a light source can be configured to generate a narrow range of wavelengths. In another embodiment, the light emitted by the light source is infrared (IR) light, which can penetrate dental tissue. The light projector can be a DLP projector using a micromirror array to produce a time-varying pattern, or a diffractive optical element (DOF), or a back-illuminated mask projector, in which the light source is placed behind a mask having a spatial pattern so that the light projected onto the surface of the dental object is patterned. The back-illuminated mask projector can include a collimating lens for collimating the light from the light source, the collimating lens being placed between the light source and the mask. The mask can have a checkerboard pattern so that the illumination pattern produced is a checkerboard pattern. Alternatively, the mask can also have other patterns, such as lines or dots.

[0082] The scanning device preferably further comprises an optical component for directing the light emitted by the light source to the surface of the dental object. The specific arrangement of the optical component depends on whether the scanning device is a focused scanning device, a scanning device using triangulation, or any other type of scanning device. The same applicant further describes a focused scanning device in EP 2 442 720 B1, the entire contents of which are incorporated herein.

[0083] Light reflected from a dental object in response to illumination of the dental object is directed to an image sensor using optical components of a scanning device. The image sensor is configured to generate a plurality of images based on incident light received from the illuminated dental object. The image sensor may be a high-speed image sensor, such as an image sensor configured to acquire images with an exposure time of less than 1 / 1000 seconds or a frame rate of more than 250 frames per second (fps). As an example, the image sensor may be a rolling shutter sensor (CCD) or a global shutter sensor (CMOS). The image sensor may be a monochrome sensor including a color filter array, such as a Bayer filter, and / or additional filters that may be configured to substantially remove one or more color components from the reflected light and retain only other unremoved components before converting the reflected light into an electrical signal. For example, such additional filters may be used to remove a portion of the white light spectrum, such as a blue component, and retain only red and green components in a signal generated in response to exciting a fluorescent material of a tooth.

[0084] The network unit may be configured to connect the dental scanning system to a network including a plurality of network elements, the plurality of network elements including at least one network element configured to receive the processed data. The network unit may include a wireless network unit or a wired network unit. The wireless network unit is configured to wirelessly connect the dental scanning system to a network including a plurality of network elements, the plurality of network elements including at least one network element configured to receive the processed data. The wired network unit is configured to establish a wired connection between the dental scanning system and a network including a plurality of network elements, the plurality of network elements including at least one network element configured to receive the processed data.

[0085] The dental scanning system preferably also includes a processor configured to generate intraoral scan data by processing a two-dimensional (2D) image acquired by the scanning device. The processor may be part of the scanning device. As an example, the processor may include a field programmable gate array (FPGA) and / or a processor of an advanced RISC machine (ARM) located on the scanning device. The scan data includes information related to a three-dimensional dental object. The scan data may include any of the following: a 2D image; a 3D point cloud, depth data, texture data, intensity data, color data, and / or various combinations thereof. As an example, the scan data may include one or more point clouds, wherein each point cloud includes a set of 3D points for describing a three-dimensional dental object. As another example, the scan data may include images, each image including image data, such as image data described by image coordinates and a timestamp (x, y, t), wherein the depth information may be inferred from the timestamp. The image sensor of the scanning device may acquire multiple original 2D images of the object in response to irradiating the dental object using one or more light projectors. Multiple original 2D images may also be referred to as stacks of 2D images herein. The 2D image can then be provided as an input to a processor that processes the 2D image to generate scan data. The processing of the 2D image can include a step of determining which portion of each 2D image is focused in order to infer / generate depth information from the image. The depth information can be used to generate a 3D point cloud, which includes a set of 3D points in space, for example, points described by Cartesian coordinates (x, y, z). The 3D point cloud can be generated by a processor or other processing unit. Each 2D / 3D point can also include a timestamp that indicates the recording time of the 2D / 3D point, i.e., which image in the stack of 2D images the point comes from. The timestamp is related to the z coordinate of the 3D point, i.e., the z coordinate can be inferred from the timestamp. Therefore, the output of the processor is scan data, and the scan data can include image data and / or depth data, for example, data described by image coordinates and timestamps (x, y, t) or alternatively described as (x, y, z). In addition to scan data, the scanning device can also be configured to transmit other types of data. Examples of data include 3D information, texture information such as infrared (IR) images, fluorescent images, reflectance color images, X-ray images, and / or various combinations thereof.

[0086] Figure 1A , 1B 1C show a 2D cross-sectional view within the 3D volume space 110. Thus, the cube is visualized as a square. Figure 1A and 1B It is also shown how the invention arranges a plurality of sub-grids 102. The 2D cross-sectional view shown is oriented orthogonally to the occlusal direction of the jaws as the 3D dental object 100. For simplicity, the "dental object" will be referred to as "object" hereinafter. Figure 1A In, at least two signed distances (104A, 104B) are calculated for each of the plurality of sub-grids 102 relative to the received digital 3D dental data, and in Figure 1B In the embodiment, a sub-grid group 106 of the plurality of sub-grids 106 is identified based on the calculated at least two signed distances (104A, 104B). Then, a dental appliance is digitally designed based on the identified sub-grid group 106. In this example, the plurality of sub-grids have the same size, including the same shape and the same size. Figure 1C , a design process 108 of a dental appliance is shown. Digital 3D dental data is represented by a 3D dental object 100, and among the plurality of sub-grids 102, a sub-grid group 106 is identified based on a selection criterion. A dental appliance 200 is then designed based on the sub-grid group. Design 108 includes smoothing the dental appliance 200, otherwise sharp edges applied to the surface of the object 100 will be transferred to the dental appliance, which will cause inconvenience to the user when wearing it. The smoothing process may include expanding the digital 3D dental data and then compressing the digital 3D dental data while maintaining the distance relationship between the points identified in each sub-grid that is part of the sub-grid group.

[0087] For the sake of brevity, a "dental object" will be referred to as an "object" hereinafter.

[0088] Figure 2A , 2B , 2C, 2D and 2E show how to determine at least two signed distances (104A, 104B) of a sub-grid in the digital 3D volume space 110 including the digital 3D dental data 100. FIG. 2A to FIG. 2C In FIG. 1 , a sub-grid 102 is shown, which includes at least two points, a first point 112A and at least a second point 112B, and in these examples, a signed distance to the surface is determined for each point ( 112A, 112B). Figure 2A In , two points (112A, 112B) are located on the same side of the surface 100 of the object 100, resulting in at least two signed distances (104A, 104B) being positive or negative. In this example, the sub-mesh does not include a part of the object 100, i.e., the digital 3D dental data 100. Figure 2B In , the sub-grid includes at least two signed distances (104A, 104B) with opposite signs, namely a positive signed distance and a negative signed distance. This indicates that the sub-grid 102 includes at least a portion of the object 100. Figure 2C In the example, at least two signed distances (104A, 104B) have the same sign, that is, positive or negative. Figure 2A Similar to the example shown in , sub-grid 102 does not include at least a portion of object 100. Figure 2A ,2B In 2C, the subgrid 102 of the plurality of subgrids includes a shape including at least a first point 112A and at least a second point 112B, and wherein a first signed distance 104A is determined between the first point 112A and the digital 3D dental data 100, and at least a second signed distance 104B is determined between at least the second point 112B and the digital 3D dental data 100, and wherein the at least two signed distances include the first signed distance 104A and the second signed distance 104B. The first signed distance 104A is a minimum distance between the first point 112A and the digital 3D dental data 100, and wherein the second signed distance 104B is a minimum distance between the second point 112B and the digital 3D dental data 100. Figure 2A , 2B In the example shown in FIG. 2C , the sub-grid 102 includes a plurality of corner points. Figure 2B 1 is a diagram showing a selection criterion for a sub-grid 102 that is part of a sub-grid group. In this example, the selection criterion specifies that at least two signed distances (104A, 104B) need to have different signs, such as positive and negative. In another example, a sub-grid 102 may include a plurality of edge points, or a combination of one or more corner points (112A, 112C, 112G, 112E) and one or more edge points (112B, 112D, 112F, 112H). This is shown in FIG. Figure 2D , where the sub-grid 102 includes at least two signed distances (104A, 104B) determined between a corner point 112E and the object 100 and between an edge point 112H and the object 100. Figure 2E In , more than two signed distances (104A, 104B, 104C, 104D) are determined. Figures 2A to 2E , subgrid 102 includes uniformly distributed points (112).

[0089] Figure 3A A bounding box 200 is shown, which includes the digital 3D dental data 100 and the plurality of sub-grids 102 in the digital 3D volume space 110. In this example, at least a first group of sub-grids 202 of the plurality of sub-grids are arranged outside the bounding box 200, while at least a second group of sub-grids 204 of the plurality of sub-grids are partially arranged inside the bounding box and are considered as part of the bounding box 200. The bounding box 200 includes a third group of sub-grids that are completely within the bounding box 200. Thereby, the number of sub-grids to be processed is reduced.

[0090] Figure 3BA subgrid 106 is shown as part of a subgrid group, the subgrid 106 including at least a portion of an object 200. In this example, the subgrid 106 is divided into a plurality of cells 206. For each cell in the plurality of cells 2, at least two signed cell distances are determined, and a cell group is identified based on the at least two signed cell distances, wherein a volume operation is performed on each identified cell in the cell group. In this specific example, the cells include the same shape and size.

[0091] Figure 4 An example of a digitally designed dental appliance 200 is shown. When the sub-grid group 106 is identified, a volume operation is performed on each sub-grid of the sub-grid group 106. Figure 3B As described in, by defining cells within each sub-grid in the identified sub-grid group 106, volumetric operations may be more efficient in terms of processing power. Thus, by introducing cells, the area or amount of digital 3D dental data to be volumetrically processed can be further reduced. In the design of the dental appliance 200, at least the first surface of the dental appliance 200 is designed based on volumetric operations. In the design of the dental appliance 200, at least the second surface of the dental appliance 200 is designed based on volumetric operations. The first surface may be the inner surface of the dental appliance 200, and the second surface may be the outer surface of the dental appliance 200. The inner surface may be closer to the tongue than the outer surface.

[0092] Figure 5A , 5B 5 and 5C show an example of a computer-implemented method for smoothing the surface of a dental appliance. Figure 5A The digital 3D dental data 100A is shown in the digital 3D volume space 110, and Figure 5B In , an offset is added to the signed distance of the identified sub-grid group 106, thereby extending the 3D digital dental data. Based on the volume operation of the extended 3D digital dental data 100B, at least an extended surface is determined. Figure 5B It can be seen that Figure 5A The expanded surface of the object 100B is smoother than the object 100A in the figure. In order to maintain a smooth surface when compressing the expanded surface to a size of a dental appliance suitable for the patient's teeth / mouth, the offset value is subtracted from the expanded signed distance to determine a compressed signed distance of the compressed identified sub-mesh group 106. The compressed sub-mesh group includes compressed digital 3D surface data 100C determined based on the expanded digital 3D surface data 100B, and based on a second volume operation of the compressed digital 3D surface data 100C, the surface of the dental appliance is determined, see Figure 5C .

[0093] Fig. 6A ,6B 6C show an example of a method 300 for designing a dental appliance 200. Fig. 6A 3, the process includes calculating 301 an extended signed distance for a plurality of extended sub-meshes by adding an offset value to each calculated signed distance for the identified group of sub-meshes. Determining 304 a compressed signed distance for each compressed sub-mesh in a plurality of compressed sub-meshes by subtracting the offset value of the extended signed distance for the plurality of extended sub-meshes, wherein the plurality of compressed sub-meshes include compressed digital 3D surface data determined based on the extended digital 3D surface data. Determining 308 a surface of the dental appliance based on a volume operation 307 including the plurality of compressed sub-meshes.

[0094] Figure 6B Another example of method 300 is shown. Fig. 6A The method described in is similar to that described in , but with additional steps. For example, after determining 301 an extended signed distance for a plurality of extended sub-grids, a first volume operation is performed 302 on the extended digital 3D dental data in the plurality of extended sub-grids. An extended surface is determined 303 based on the first volume operation, and the extended surface includes the extended digital 3D surface data corresponding to the plurality of extended sub-grids. A compressed signed distance is determined 304 for a plurality of compressed sub-grids by subtracting an offset value of the extended signed distance of the plurality of extended sub-grids. The plurality of compressed sub-grids include compressed digital 3D surface data determined based on the extended digital 3D surface data. A second volume operation is performed 305 on the compressed digital 3D surface data in the plurality of compressed sub-grids. A compressed surface is determined based on the second volume operation, and the compressed surface includes the compressed digital 3D surface data corresponding to the plurality of compressed sub-grids, and a surface of the dental appliance is set 306 based on the compressed surface.

[0095] Figure 6C Another example of method 300 is shown. The method comprises the following steps:

[0096] Calculating 309 extended outer signed distances for a plurality of extended outer sub-grids by adding an outer offset value to each calculated signed distance of the identified group of sub-grids, wherein the plurality of extended outer sub-grids comprises the digital 3D dental data of the extended identified group of sub-grids;

[0097] Calculating 309 an extended inner signed distance for a plurality of extended inner sub-grids by adding an inner offset value to each calculated signed distance of the identified group of sub-grids, wherein the plurality of extended inner sub-grids comprises the digital 3D dental data of the identified group of sub-grids;

[0098] · performing 310 a first volume operation on the expanded digital 3D dental data of the plurality of expanded outer sub-grids and the plurality of expanded inner sub-grids;

[0099] determining 311 an extended outer surface and an extended inner surface based on the first volume operation, wherein the extended outer surface comprises extended digital 3D surface data corresponding to the plurality of extended outer sub-meshes, and the extended inner surface comprises extended digital 3D surface data corresponding to the plurality of extended inner sub-meshes;

[0100] Calculating 312 compressed outer signed distances of a plurality of compressed outer sub-grids by subtracting outer offset values ​​of the expanded outer signed distances of the plurality of expanded outer sub-grids, wherein the plurality of compressed outer sub-grids include compressed digital 3D surface data determined based on the expanded outer surface;

[0101] Calculating 312 compressed inner signed distances of a plurality of compressed inner sub-meshes by subtracting inner offset values ​​of the expanded inner signed distances of the plurality of expanded inner sub-meshes, wherein the plurality of compressed inner sub-meshes include compressed digital 3D surface data determined based on the expanded inner surface;

[0102] · performing 313 a second volume operation on the compressed digital 3D tooth data of the plurality of compressed outer sub-grids and the plurality of compressed inner sub-grids;

[0103] determining 314 a compressed outer surface and a compressed inner surface based on the second volume operation, wherein the compressed outer surface includes compressed digital 3D surface data corresponding to the plurality of compressed outer sub-meshes and the compressed inner surface includes compressed digital 3D surface data corresponding to the plurality of compressed inner sub-meshes, and

[0104] - Based on the compressed outer surface and the compressed inner surface, respectively, an outer surface and an inner surface of the dental appliance are arranged 316 .

[0105] The sizes of the plurality of sub-grids are determined based on the type of dental appliance to be digitally designed.

[0106] The method for designing a dental appliance includes widening a portion of a dental appliance 600 to improve the comfort of wearing the dental appliance 600, see Fig. 7A and 7B . Fig. 7A and 7B A cross-sectional view of a dental appliance 600 is shown. Fig. 7AIn the present invention, a widening reference point 606 on the dental appliance 600 is determined by determining the maximum width of the dental appliance along a transverse axis 602 extending from the front to the back of the dental appliance 600, wherein the transverse axis is orthogonal to an insertion axis 604 extending from the upper portion 612 to the bottom 610 of the dental appliance 600, and a portion of the dental appliance 600 located between the widening reference point 600 and the bottom 610 of the dental appliance 600 is widened along the transverse axis 602.

[0107] The widening may be provided to the width of the free space 614 enclosed by the surface of the dental appliance 600 .

[0108] The widening may be provided to the width of the free space between the first surface 616 and the second surface 617 of the dental appliance 600 .

[0109] Figure 7B The final dental appliance 600 is shown after the widening has been applied.

[0110] Although some embodiments have been described and shown in detail, the present disclosure is not limited to these details, but can also be embodied in other ways within the scope of the subject matter defined by the appended claims. It is particularly understood that other embodiments can be adopted and the structure and function can be modified without departing from the scope of the present invention.

[0111] The benefits, other advantages and solutions to problems of the present invention have been described herein with respect to specific embodiments. However, these benefits, advantages, solutions to problems, and any components / units that may cause any benefit, advantage or solution to occur or become more obvious shall not be considered as key, essential or basic features or components / elements of any or all claims or the present invention. Therefore, the scope of the present invention shall be limited only by the appended claims, in which the singular components / units / elements mentioned do not mean "one and only one", unless expressly stated, but "one or more". Each claim may refer to any of the previous claims, and "any" is understood to mean "any one or more" in the previous claims.

[0112] In the detailed description and / or claims, structural features of the apparatus described above are intended to be combined with steps of the method when appropriately replaced with corresponding procedures.

[0113] When used, the singular forms "one", "an" and "the" are also intended to include the plural forms (i.e., have the meaning of "at least one"), unless otherwise expressly stated. It should be further understood that the terms "include", "comprise", "include" and / or "comprises" when used in this specification indicate the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or their groups. It should also be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to another element, but there may also be intermediate elements, unless otherwise expressly stated. In addition, "connected" or "coupled" as used herein may include wireless connections or couplings. When used in this article, the term "and / or" includes any and all combinations of one or more associated listed items. The steps of any disclosed method are not limited to the exact order described herein, unless otherwise expressly stated.

[0114] It should be understood that the "one embodiment" or "an embodiment" or "an aspect" or features included as "may" mentioned throughout this specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present disclosure. In addition, in one or more embodiments of the present disclosure, specific features, structures or characteristics may be appropriately combined. The foregoing description is intended to enable those skilled in the art to practice the various aspects described herein. Various modifications to these aspects are readily implementable by those skilled in the art, and the general principles defined herein may also be applied to other aspects.

[0115] The claims are not intended to be limited to the aspects shown herein, but are to be given the full scope consistent with the claim language, wherein an element referred to in the singular does not mean "one and only one" unless specifically stated, but rather means "one or more." "Some" means one or more unless specifically stated otherwise.

[0116] List of items

[0117] 1. A computer-implemented method for digitally designing a dental appliance, comprising:

[0118] Receiving digital 3D dental data (100) in a digital 3D volume space (110);

[0119] calculating at least two signed distances (104A, 104B) for each of a plurality of sub-grids (102) relative to the received digital 3D dental data;

[0120] Based on the calculated at least two signed distances (104A, 104B), identifying a sub-mesh group (106) from the plurality of sub-meshes (102), such that the identified sub-mesh group (106) collectively corresponds to the received digital 3D dental data (100); and

[0121] Based on the identified sub-mesh groups (106), the dental appliance is digitally designed (108).

[0122] 2. A computer-implemented method for digitally designing a dental appliance, comprising:

[0123] receiving digital 3D dental data in a digital 3D volume space;

[0124] Relative to the received digital 3D dental data, calculating at least two signed distances (104A, 104B) for each of the plurality of sub-grids (102),

[0125] identifying a sub-mesh group from the plurality of sub-meshes based on the calculated at least two signed distances, such that the identified sub-mesh group collectively corresponds to a portion of a bounding box containing the received digital 3D dental data; and

[0126] A dental appliance is digitally designed based on the identified sub-mesh groups.

[0127] 3. A computer-implemented method for digitally designing a dental appliance, comprising:

[0128] receiving digital 3D dental data in a digital 3D volume space;

[0129] calculating at least two signed distances (104A, 104B) for each of a plurality of sub-grids (102) relative to the received digital 3D dental data;

[0130] Based on the calculated at least two signed distances, ignoring a plurality of sub-grids of the plurality of sub-grids that do not contain 3D digital dental data;

[0131] A dental appliance is digitally designed based on a group of sub-meshes of the plurality of sub-meshes that do not form a portion of the ignored plurality of sub-meshes.

[0132] 4. A computer-implemented method for digitally designing a dental appliance, comprising:

[0133] receiving digital 3D dental data in a digital 3D volume space;

[0134] calculating at least two signed distances (104A, 104B) for each of a plurality of sub-grids (102) relative to the received digital 3D dental data,

[0135] Each subgrid includes a plurality of cells;

[0136] Based on the calculated at least two signed distances, omitting a sub-mesh cluster from a sub-mesh corresponding to a bounding box containing the 3D digital dental data, such that the sub-mesh cluster does not contain a volume of interest; and

[0137] A dental appliance is digitally designed based on a group of sub-meshes of the plurality of sub-meshes that do not form a portion of the ignored plurality of sub-meshes.

[0138] 5. The computer-implemented method according to any of the preceding items, further comprising defining a plurality of sub-grids in the digital 3D volume space, wherein the plurality of sub-grids are of equal size.

[0139] 6. The computer-implemented method of item 5, wherein the plurality of equally sized sub-grids comprise a same shape and a same size.

[0140] 7. A computer-implemented method according to any of the preceding items, further comprising assigning the identified sub-mesh group to a first surface or a second surface of the digital 3D dental data based on at least two signed distances, wherein the at least two signed distances include a first signed distance determined between a first point of a sub-mesh in the identified sub-mesh group and the first surface, and a second signed distance determined between a second point of a sub-mesh in the identified sub-mesh group and the second surface.

[0141] 8. The computer-implemented method of item 7, wherein the shortest signed distance of the first signed distance and the second signed distance determines whether the identified sub-mesh is assigned to the first surface or the second surface of the digital 3D digital dental data.

[0142] 9. A computer-implemented method according to any of the preceding items, wherein each sub-mesh of the plurality of sub-meshes comprises a shape comprising at least a first point and at least a second point, and wherein a first signed distance is determined between the first point and the digital 3D dental data and at least a second signed distance is determined between the at least second point and the digital 3D dental data, wherein the at least two signed distances comprise the first signed distance and the second signed distance.

[0143] 10. The computer-implemented method of clause 7, wherein the first signed distance is a minimum distance between the first point and the digital 3D dental data, and wherein the second signed distance is a minimum distance between the second point and the digital 3D dental data.

[0144] 11. The computer-implemented method of any preceding claim, wherein each sub-grid of the plurality of sub-grids comprises a shape having a plurality of corner points.

[0145] 12. The computer-implemented method of item 11, wherein each of the plurality of sub-grids comprises a plurality of edge points along one or more edges connecting a pair of corner points of the plurality of corner points.

[0146] 13. The computer-implemented method of items 7 and 12, wherein the plurality of corner points and / or the plurality of edge points include a first point and at least a second point.

[0147] 14. The computer-implemented method of item 13, wherein the plurality of edge points are evenly distributed along an edge of at least one of the plurality of sub-grids.

[0148] 15. A computer-implemented method according to item 11, wherein the calculated at least two signed distances of each of the multiple sub-grids are determined as between a first corner point of the multiple corner points and the digital 3D dental data and between a second corner point of the multiple corner points and the digital 3D dental data.

[0149] 16. A computer-implemented method according to item 12, wherein the calculated signed distance of each of the multiple sub-grids is determined as between a first edge point of a plurality of edge points or a first corner point of a plurality of corner points and the digital 3D dental data and between a second edge point of the plurality of edge points or a second corner point of the plurality of corner points and the digital 3D dental data.

[0150] 17. The computer-implemented method of clause 7, wherein identifying the group of sub-grids comprises identifying the sub-grids when at least two signed distances determined at the first point and at least the second point both satisfy a selection criterion.

[0151] 18. A computer-implemented method according to any one of items 11 to 16, wherein identifying the sub-grid group includes identifying the sub-grid when at least two signed distances determined at the first corner point and at least the second corner point both meet a selection criterion.

[0152] 19. A computer-implemented method according to any one of items 11 to 16, wherein identifying a sub-grid group includes identifying a sub-grid when at least two signed distances determined at a first corner point or a first edge point and at least a second corner point or at least a second edge point both meet a selection criterion.

[0153] 20. The computer-implemented method of any one of items 17 to 19, wherein the selection criteria comprises: the at least two signed distances comprise at least one positive signed distance and at least one negative signed distance.

[0154] 21. The computer-implemented method of any preceding claim, further comprising generating a bounding box comprising the digital 3D dental data and at least a first group of sub-grids of the plurality of sub-grids located outside the bounding box.

[0155] 22. The computer-implemented method of any preceding claim, further comprising generating a bounding box comprising a second group of sub-grids of the plurality of sub-grids, the second group of sub-grids comprising sub-grids at least partially located inside the bounding box.

[0156] 23. The computer-implemented method of any preceding claim, wherein digital design of the dental appliance comprises performing volumetric operations based at least on the identified sub-mesh groups.

[0157] 24. The computer-implemented method of any one of items 1 to 22, wherein the digital design of the dental appliance comprises performing a volumetric operation based on the received digital 3D dental data of at least the identified sub-mesh group.

[0158] 25. The computer-implemented method of any one of claims 1 to 22, wherein the digital design of the dental appliance comprises performing volumetric operations based on defined parameter values.

[0159] 26. A computer-implemented method according to any of the preceding items, wherein each sub-grid in the identified sub-grid group includes a plurality of cells, wherein at least two signed cell distances are determined for each cell in the plurality of cells, and a cell group is identified based on the at least two signed cell distances, and wherein a volume operation is performed for each identified cell in the cell group.

[0160] 27. The computer-implemented method of any one of items 23 to 26, further comprising positioning at least a first surface of the dental appliance based on a volumetric calculation.

[0161] 28. The computer-implemented method of any one of items 23 to 27, further comprising positioning at least a second surface of the dental appliance based on a volumetric calculation.

[0162] 29. The computer-implemented method of any one of clauses 1 to 26, further comprising:

[0163] Calculating an extended signed distance of a plurality of extended sub-meshes by adding an offset value to each calculated signed distance of the identified group of sub-meshes, wherein the plurality of extended sub-meshes comprises the digital 3D dental data of the identified group of sub-meshes that have been extended;

[0164] · performing a first volumetric operation on the extended digital 3D dental data in the plurality of extended sub-grids;

[0165] determining an extended surface based on the first volume operation, and the extended surface includes extended digital 3D surface data corresponding to the plurality of extended sub-meshes;

[0166] Calculating compressed signed distances of a plurality of compressed sub-meshes by subtracting offset values ​​of the expanded signed distances of the plurality of expanded sub-meshes, wherein the plurality of compressed sub-meshes include compressed digital 3D surface data determined based on the expanded digital 3D surface data;

[0167] performing a second volumetric operation on the compressed digital 3D surface data in the plurality of compressed sub-grids;

[0168] · providing a compressed surface based on the second volume operation, and the compressed surface comprises compressed digital 3D surface data corresponding to the plurality of compressed sub-meshes; and

[0169] • Setting the surface of the dental appliance based on the compression surface.

[0170] 30. The computer-implemented method of any one of clauses 1 to 26, further comprising:

[0171] Calculating extended outer signed distances of a plurality of extended outer sub-grids by adding an outer offset value to each calculated signed distance of the identified group of sub-grids, wherein the plurality of extended outer sub-grids comprises the digital 3D dental data of the extended identified group of sub-grids;

[0172] Calculating extended inner signed distances of a plurality of extended inner sub-grids by adding an inner offset value to each calculated signed distance of the identified group of sub-grids, wherein the plurality of extended inner sub-grids comprises the digital 3D dental data of the identified group of sub-grids;

[0173] performing a first volumetric operation on the expanded digital 3D dental data of the plurality of expanded outer sub-grids and the plurality of expanded inner sub-grids;

[0174] determining an extended outer surface and an extended inner surface based on the first volume operation, wherein the extended outer surface includes extended digital 3D surface data corresponding to the plurality of extended outer sub-meshes, and the extended inner surface includes extended digital 3D surface data corresponding to the plurality of extended inner sub-meshes;

[0175] Calculating compressed outer signed distances of a plurality of compressed outer sub-meshes by subtracting outer offset values ​​of the expanded outer signed distances of the plurality of expanded outer sub-meshes, wherein the plurality of compressed outer sub-meshes comprise compressed digital 3D surface data determined based on the expanded outer surface;

[0176] Calculating compressed inner signed distances of a plurality of compressed inner sub-meshes by subtracting inner offset values ​​of the expanded inner signed distances of the plurality of expanded inner sub-meshes, wherein the plurality of compressed inner sub-meshes include compressed digital 3D surface data determined based on the expanded inner surface;

[0177] performing a second volumetric operation on the compressed digital 3D dental data of the plurality of compressed outer sub-meshes and the plurality of compressed inner sub-meshes;

[0178] determining a compressed outer surface and a compressed inner surface based on the second volume operation, wherein the compressed outer surface comprises compressed digital 3D surface data corresponding to the plurality of compressed outer sub-meshes and the compressed inner surface comprises compressed digital 3D surface data corresponding to the plurality of compressed inner sub-meshes; and

[0179] Based on the compressed outer surface and the compressed inner surface, the outer surface and the inner surface of the dental appliance are arranged respectively.

[0180] 31. The computer-implemented method of any one of clauses 1 to 26, further comprising:

[0181] Calculating an extended outer signed distance and an extended inner signed distance for the plurality of sub-grids by adding the outer offset value and the inner offset value to each calculated signed distance for the identified group of sub-grids, respectively;

[0182] determining an extended outer surface and an extended inner surface based on the first volume operation and the digital 3D dental data of the identified sub-mesh group, wherein the extended outer surface and the extended inner surface comprise the extended digital 3D surface data;

[0183] Calculating compressed outer signed distances and compressed inner signed distances of the plurality of sub-grids by subtracting the outer offset value and the inner offset value from the extended outer signed distance and the extended inner signed distance, respectively;

[0184] determining a compressed outer surface and a compressed inner surface based on the second volume operation and the extended digital 3D surface data of the extended outer surface and the extended inner surface, respectively;

[0185] Based on the compressed outer surface and the compressed inner surface, the outer surface and the inner surface of the dental appliance are arranged respectively.

[0186] 33. The computer-implemented method of any preceding claim, wherein the size of the plurality of sub-meshes is determined based on the type of dental appliance to be digitally designed.

[0187] 34. The computer-implemented method of any preceding claim, further comprising widening a portion of the dental appliance to improve comfort in wearing the dental appliance.

[0188] 35. The computer-implemented method of clause 34, wherein the widening comprises:

[0189] Determining a widening reference point on the dental appliance by determining the maximum width of the dental appliance along a transverse axis extending from the front to the back of the dental appliance, wherein the transverse axis is orthogonal to an insertion axis extending from the top to the bottom of the dental appliance; and

[0190] • Widening the portion of the dental appliance along the transverse axis between the widening reference point and the base of the dental appliance.

[0191] 36. The computer-implemented method of item 34, wherein the widening is provided to the width of a free space enclosed by a surface of the dental appliance.

[0192] 37. The computer-implemented method of items 28 and 34, wherein the widening is provided to the width of a free space between the first surface and the second surface of the dental appliance.

[0193] 38. A computer-implemented method according to any of the preceding claims, wherein the identified plurality of sub-grids comprises cells having the same shape and the same size.

Claims

1. A computer-implemented method for digitally designing a dental appliance, comprising: receiving digital 3D dental data in a digital 3D volumetric space, wherein the digital 3D volume scan comprises a plurality of sub-meshes, and wherein the digital 3D dental data comprises a first surface and a second surface; calculating at least two signed distances for each of the plurality of sub-grids relative to the received digital 3D dental data, wherein the at least two signed distances include a first signed distance and a second signed distance, and the first signed distance is determined between a first point of a sub-grid in the identified group of sub-grids and the first surface, and the second signed distance is determined between a second point of a sub-grid in the identified group of sub-grids and the second surface; identifying a sub-mesh group from the plurality of sub-meshes based on the calculated at least two signed distances, such that the identified sub-mesh group collectively corresponds to the received digital 3D dental data; and The dental appliance is digitally designed based on the identified sub-mesh groups.

2. A computer-implemented method according to any one of the preceding claims, further comprising defining the plurality of sub-grids in the digital 3D volume space, wherein the plurality of sub-grids are of equal size.

3. The computer-implemented method of claim 2, wherein: The plurality of sub-grids of equal size include a same shape and a same size.

4. A computer-implemented method according to any one of the preceding claims, wherein: The shortest signed distance of the first signed distance and the second signed distance determines whether the identified sub-mesh is assigned to the first surface or the second surface of the digital 3D digital dental data.

5. A computer-implemented method according to any one of the preceding claims, wherein: The first signed distance is a minimum distance between the first point and the digital 3D dental data, and wherein the second signed distance is a minimum distance between the second point and the digital 3D dental data.

6. A computer-implemented method according to any one of the preceding claims, wherein: Each of the plurality of sub-grids comprises a shape having a plurality of corner points, and wherein each of the plurality of sub-grids comprises a plurality of edge points along one or more edges connecting a pair of corner points among the plurality of corner points, and wherein the plurality of corner points and / or the plurality of edge points comprises a first point and at least a second point.

7. The computer-implemented method of claim 6, wherein: The plurality of edge points are evenly distributed along an edge of at least one sub-grid among the plurality of sub-grids.

8. The computer-implemented method of claim 6, wherein: The calculated at least two signed distances of each of the plurality of sub-grids are determined between a first corner point of the plurality of corner points and the digital 3D dental data, and between a second corner point of the plurality of corner points and the digital 3D dental data.

9. The computer-implemented method of claim 6, wherein: The calculated signed distance for each of the plurality of subgrids is determined between a first edge point among the plurality of edge points or a first corner point among the plurality of corner points and the digital 3D dental data, and between a second edge point among the plurality of edge points or a second corner point among the plurality of corner points and the digital 3D dental data.

10. A computer-implemented method according to any one of the preceding claims, wherein: Identifying the group of sub-grids includes identifying a sub-grid when at least two signed distances determined at the first point and at least a second point both satisfy a selection criterion.

11. A computer-implemented method according to any one of claims 6 to 9, wherein: Identifying the group of sub-meshes includes identifying a sub-mesh when at least two signed distances determined at the first corner point and at least a second corner point both satisfy a selection criterion.

12. A computer-implemented method according to any one of claims 6 to 9, wherein: Identifying the group of sub-meshes includes identifying a sub-mesh when at least two signed distances determined at a first corner point or a first edge point and at least a second corner point or at least a second edge point both satisfy a selection criterion.

13. The computer-implemented method of any one of claims 6 to 12, wherein the selection criteria comprises: The at least two signed distances include at least one positive signed distance and at least one negative signed distance.

14. A computer-implemented method according to any one of the preceding claims, the method comprising: A bounding box is determined including the digital 3D dental data and at least a first group of sub-grids among the plurality of sub-grids arranged outside the bounding box, wherein the first group of sub-grids corresponds to sub-grids related to an extended surface of the first surface or the second surface, wherein the extended surface is determined by adding an offset value to the digital 3D dental data defining the first surface or the second surface.

15. The computer-implemented method of claim 14, comprising: A second group of sub-meshes of the plurality of sub-meshes that are partially within the bounding box is determined, wherein the second group of sub-meshes corresponds to the digital 3D dental data of the first surface or the second surface.

16. A computer-implemented method according to any one of the preceding claims, wherein: The digital design of the dental appliance includes performing a volumetric operation based on the received digital 3D dental data of at least the identified sub-mesh group.

17. A computer-implemented method according to any one of the preceding claims, wherein: Each sub-grid in the identified sub-grid group includes a plurality of cells, and wherein at least two signed cell distances are determined for each cell in the plurality of cells, and a cell group is identified based on the at least two signed cell distances, and wherein a volume operation is performed for each identified cell in the cell group.

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