CN118097032A

CN118097032A - Base supplementing method, medium and equipment for dental crown three-dimensional model

Info

Publication number: CN118097032A
Application number: CN202410489916.1A
Authority: CN
Inventors: 黄炜; 王康; 甘博城
Original assignee: Fuzhou Hailijia Oral Technology Co ltd
Current assignee: Fuzhou Hailijia Oral Technology Co ltd
Priority date: 2024-04-23
Filing date: 2024-04-23
Publication date: 2024-05-28

Abstract

The invention provides a base complement method, medium and equipment of a dental crown three-dimensional model, wherein the method obtains a second dental crown three-dimensional model by carrying out smoothing treatment on the edge of a first dental crown three-dimensional model; then, reading a first adjacent point list of a crown three-dimensional model corresponding to the current single tooth, and searching a second adjacent point which is closest to each first adjacent point in the first adjacent point list in the edge of the second crown three-dimensional model to obtain a second adjacent point list; and then taking all second adjacent points recorded in the second adjacent point list as references, and adopting a plurality of patches with preset shapes to complement the second dental crown three-dimensional model to obtain a third dental crown three-dimensional model. When the dental crown base is generated, the distribution condition of the edge adjacent points of the original dental crown model and the adjacent dental crown model is considered, and the dental crown three-dimensional model is subjected to a certain degree of complementation based on the adjacent points and then is regenerated into the base, so that the completed base can better reflect the original tooth structure.

Description

Base supplementing method, medium and equipment for dental crown three-dimensional model

Technical Field

The invention relates to the field of tooth image processing, in particular to a base filling method, medium and equipment of a dental crown three-dimensional model.

Background

With the continuous development of digital oral technology, an oral auxiliary diagnosis and treatment system based on three-dimensional digital technology is increasingly dependent on accurately establishing a three-dimensional digital model of dental jaw and dental crown of a patient. Limited by the influence of the error of the existing three-dimensional dental crown model balancing algorithm, the edge of the processed independent dental crown model often has a concave area, and if the edge is directly used for vertical projection to generate a dental crown model base, the generated base is also concave, and the quality of dental braces generated based on the dental crown model is directly influenced. And an overlapping edge area often exists between the original dental crown model and the adjacent dental crown model, and the base is generated by the edge of a certain dental crown model alone, so that the structure of the original dental crown model cannot be reflected well, and the quality of the dental floss is further affected.

Disclosure of Invention

Therefore, a technical scheme of cavity filling of a three-dimensional model of a dental crown is needed to be provided, and the technical scheme is used for solving the problems that the existing method for filling the base of the three-dimensional model of the dental crown has concave base, the original structure of the teeth of a patient cannot be well reflected after the base is filled.

In order to solve the problems, the application provides the following scheme:

in a first aspect, the present application provides a method for supplementing a base of a three-dimensional model of a dental crown, the three-dimensional model of a dental crown being formed by stitching a plurality of patches of preset shape, the method comprising the steps of:

S1: obtaining a crown three-dimensional model corresponding to a single tooth from an original dental jaw three-dimensional model, and removing non-manifold geometric elements of the crown three-dimensional model corresponding to the single tooth to obtain a first crown three-dimensional model, wherein the non-manifold geometric elements comprise non-manifold vertexes, non-manifold edges or non-manifold surfaces in the surface piece;

S2: smoothing the edge of the first dental crown three-dimensional model to obtain a second dental crown three-dimensional model;

S3: reading a first adjacent point list of a crown three-dimensional model corresponding to a current single tooth, wherein a plurality of first adjacent points are recorded in the first adjacent point list, the first adjacent points are edge points where intersection exists between the crown three-dimensional model corresponding to the current single tooth and a crown three-dimensional model corresponding to an adjacent tooth in an original dental three-dimensional model, and searching for second adjacent points closest to each first adjacent point in the edge of the second crown three-dimensional model to obtain a second adjacent point list;

S4: taking all second adjacent points recorded in the second adjacent point list as references, and adopting a plurality of patches with preset shapes to complement the second dental crown three-dimensional model to obtain a third dental crown three-dimensional model;

S5: calculating the center point coordinates of the bottom edge of the third dental crown three-dimensional model, moving the center point coordinates of the bottom edge along the dental axis direction of the third dental crown three-dimensional model by a first preset distance to obtain a first center point, and sequentially connecting the bottom edge point of the third dental crown three-dimensional model with the first center point to form a closed fourth dental crown three-dimensional model;

S6: and creating a plane perpendicular to the dental axis direction of the third dental crown three-dimensional model, and transversely cutting the fourth dental crown three-dimensional model by adopting the plane to obtain a fifth dental crown three-dimensional model with the full base.

Further, the first list of adjacencies is obtained according to the following way:

S21: judging whether a certain dental crown three-dimensional model in the original dental jaw three-dimensional model is adjacent to the dental crown three-dimensional model or not;

if the adjacent dental crown three-dimensional model does not exist, directly skipping the current dental crown three-dimensional model, and executing the step S21 again aiming at the next dental crown three-dimensional model;

If the adjacent dental crown three-dimensional model exists, further judging whether an adjacent point exists between the current dental crown three-dimensional model and the adjacent dental crown three-dimensional model, if the adjacent point does not exist, skipping the current dental crown three-dimensional model, executing the step S21 again for the next dental crown three-dimensional model, and if the adjacent point exists, recording the coordinate position of the current adjacent point;

obtaining a first adjacent point list corresponding to the current dental crown three-dimensional model according to the coordinate positions of all the recorded adjacent points;

Whether or not there is an abutment point between the current crown three-dimensional model and the abutment crown three-dimensional model is determined according to the following manner:

extracting edge points of the current dental crown three-dimensional model and edge points corresponding to adjacent dental crown three-dimensional models;

Constructing a k-d tree for the edge points of the current dental crown three-dimensional model, traversing and calculating one by one whether edge points with the distance within a first preset distance error range from the edge points of the adjacent dental crown three-dimensional model exist or not, if so, indicating that the adjacent points exist between the current dental crown three-dimensional model and the adjacent dental crown three-dimensional model, otherwise, indicating that the adjacent points do not exist between the current dental crown three-dimensional model and the adjacent dental crown three-dimensional model.

Further, naming each crown three-dimensional model file in the original dental jaw three-dimensional model according to whether the crown three-dimensional model file is continuously named or not;

the step S1 comprises the following steps:

Acquiring a first file name of a current dental crown three-dimensional model;

acquiring a second file name of the dental crown three-dimensional model positioned on the left side of the current dental crown three-dimensional model and/or acquiring a third file name of the dental crown three-dimensional model positioned on the right side of the current dental crown three-dimensional model;

Determining whether the first file name and the second file name are continuous or not, and/or determining whether the first file name and the third file name are continuous or not.

Further, step S4 includes:

Sequentially calculating the included angle of two adjacent sides corresponding to each second adjacent point, finding out the second adjacent point with the smallest included angle, and determining the number of patches with preset shapes to be added;

Updating edge point information of the second dental crown three-dimensional model with the corresponding number of patches, finding out an edge point with the minimum next included angle based on the edge point information of the current second dental crown three-dimensional model, and determining the number of patches with preset shapes to be added based on the newly found edge point with the minimum next included angle; repeating the steps until the boundary repair of the second dental crown three-dimensional model is completed, and obtaining a third dental crown three-dimensional model.

Further, the preset-shape dough sheet is a triangular dough sheet;

The determining the number of preset shaped patches to be added includes:

calculating the distance s between two adjacent edge points of the second adjacent point with the minimum current included angle or the edge point with the minimum included angle, wherein if the distance s is smaller than 2 times of the average side length of the closed triangle, the number of triangular patches required to be increased is 1, and if the distance s is larger than 2 times of the average side length of the closed triangle, the number of triangular patches required to be increased is 2;

the closed triangle is a triangle formed by the second adjacent point with the minimum current included angle and two adjacent edge points, or a triangle formed by the edge point with the minimum current included angle and two adjacent edge points.

Further, the step of transversely cutting the fourth dental crown three-dimensional model by using the plane to obtain a fifth dental crown three-dimensional model with a full base comprises the following steps:

Performing ellipse fitting on the cut cross section edge points, and fitting the cross section into an ellipse shape to obtain a fifth dental crown three-dimensional model;

the elliptical fitting of the cut cross-sectional edge points comprises the following steps:

calculating the center points of all edge points of the cut cross section, carrying out centering treatment on all edge points of the cross section, calculating covariance matrixes of the edge points after the centering treatment, and solving eigenvalues and eigenvectors of the covariance matrixes to determine major axes and minor axes of ellipses;

sequencing the characteristic values, taking the first two main components to carry out two-dimensional projection, carrying out ellipse fitting on a two-dimensional plane, and converting the fitted ellipse back to elliptical point coordinates in a three-dimensional space according to parameters of the fitted ellipse on the two-dimensional plane;

and aligning the coordinates of the elliptic points with the edge points of the cross section after the original cutting, and sequentially replacing the edge points of the cross section after the original cutting with the coordinates of the elliptic points.

Further, before the edge of the first dental crown three-dimensional model is smoothed, the method further comprises the following steps:

judging whether each facial piece in the first dental crown three-dimensional model is a raised edge facial piece or not in sequence, and if so, removing the raised edge facial piece from the first dental crown three-dimensional model;

the edge-warped dough sheet is determined according to the following mode:

Calculating normal vectors corresponding to all patches in the first dental crown three-dimensional model, sequentially judging whether the included angle between the normal vector corresponding to each patch and the normal vector mean value of all surrounding patches corresponding to each patch exceeds a preset included angle, if so, further judging whether the Digerstros distance between a preset coordinate point in the current patch and a preset coordinate point in a patch which is nearest to and is positioned at the edge position of the first dental crown three-dimensional model is smaller than the preset distance, and if so, determining the current patch as the edge-warped patch;

Or the edge-warped dough sheet is determined according to the following mode:

Judging whether the Dijiestra distance between a preset coordinate point in the current facial mask and a facial mask which is closest to the preset coordinate point and is positioned at the edge position of the first dental crown three-dimensional model is smaller than the preset distance, if so, calculating normal vectors of the current facial mask and all surrounding facial masks connected with the current facial mask, and judging whether the included angle of the normal vector average value of the current facial mask and all surrounding facial masks connected with the current facial mask exceeds the preset included angle, if so, determining the current facial mask as the edge-warped facial mask.

Further, the method further comprises:

S7: judging whether a cavity area exists in the fifth dental crown three-dimensional model, if so, determining cavity filling information according to the coordinate position of the cavity area, extracting the cavity filling information from the original dental jaw three-dimensional model, and combining the cavity filling information with the fifth dental crown three-dimensional model to obtain a sixth dental crown three-dimensional model.

The determining the cavity filling information according to the coordinate position of the cavity area, and extracting the cavity filling information from the original dental three-dimensional model comprises the following steps:

S71: converting the three-dimensional coordinates of the edge points of the cavity area into two-dimensional plane coordinates, and sequentially connecting the two-dimensional plane coordinates corresponding to all the edge points in the fifth dental crown three-dimensional model to obtain a polygonal area;

S72: traversing the two-dimensional coordinates of the central points corresponding to the patches in the original dental three-dimensional model one by one, judging whether the two-dimensional coordinates of the central points corresponding to the patches in the original dental three-dimensional model are positioned in the polygonal area, and if so, recording the two-dimensional coordinates of the central points corresponding to the patches and the three-dimensional coordinates of the vertexes corresponding to the patches;

S73: after traversing, obtaining the recorded vertex three-dimensional coordinates corresponding to all the patches, and extracting the corresponding patches from the original dental three-dimensional model as the cavity complement information according to the recorded vertex three-dimensional coordinates.

In a second aspect, the present application provides a computer readable storage medium having stored thereon a computer program which when executed by a processor implements a method for base replenishment of a three-dimensional model of a dental crown according to the first aspect of the present application.

In a third aspect, the present application provides an electronic device, on which a computer program is stored, including a processor and a storage medium, the storage medium having stored thereon a computer program which, when executed by the processor, implements a method for base replenishment of a dental crown three-dimensional model according to the first aspect of the present application.

Different from the prior art, the invention provides a base supplementing method, medium and equipment of a three-dimensional model of a dental crown, wherein the method obtains a second three-dimensional model of the dental crown by carrying out smoothing treatment on the edge of a first three-dimensional model of the dental crown; then, reading a first adjacent point list of a crown three-dimensional model corresponding to the current single tooth, and searching a second adjacent point which is closest to each first adjacent point in the first adjacent point list in the edge of the second crown three-dimensional model to obtain a second adjacent point list; and then taking all second adjacent points recorded in the second adjacent point list as references, and adopting a plurality of patches with preset shapes to complement the second dental crown three-dimensional model to obtain a third dental crown three-dimensional model. When the dental crown base is generated, the distribution condition of the edge adjacent points of the original dental crown model and the adjacent dental crown model is considered, and the dental crown three-dimensional model is restored to the base after being complemented to a certain extent based on the adjacent points, so that the complemented base can better reflect the original tooth structure, and the quality of the dental crown three-dimensional model after the base is complemented is improved.

Drawings

FIG. 1 is a flow chart of a method for supplementing the base of a three-dimensional model of a dental crown according to a first embodiment of the present invention;

FIG. 2 is a flow chart of a method for base replenishment of a three-dimensional model of a dental crown according to a second embodiment of the present invention;

FIG. 3 is a flow chart of a method for supplementing the base of a three-dimensional model of a dental crown according to a third embodiment of the present invention;

FIG. 4 is a flow chart of a method for base replenishment of a three-dimensional model of a dental crown according to a fourth embodiment of the present invention;

FIG. 5 is a flowchart of a method for supplementing the base of a three-dimensional model of a dental crown according to a fifth embodiment of the present invention;

FIG. 6 is a flowchart of a method for supplementing the base of a three-dimensional model of a dental crown according to a sixth embodiment of the present invention;

FIG. 7 is a flowchart of a method for supplementing the base of a three-dimensional model of a dental crown according to a seventh embodiment of the present invention;

FIG. 8 is a schematic diagram of an electronic device according to an embodiment of the present invention;

FIG. 9 is a comparison of an original three-dimensional model of a dental crown and a first three-dimensional model of a dental crown obtained after removal of non-manifold geometric elements in accordance with an embodiment of the present invention;

FIG. 10 is a schematic view of a second three-dimensional model of a dental crown according to an embodiment of the present invention;

FIG. 11 is a partial detail view of the distribution of abutment points of adjacent crown three-dimensional models in an original dental three-dimensional model according to an embodiment of the present invention;

FIG. 12 is a partial detail view of the edge of a second crown three-dimensional model according to an embodiment of the present invention;

FIG. 13 is a partial detail view of a second distribution of adjacencies according to an embodiment of the present invention;

FIG. 14 is a partial detail view of a third dental crown three-dimensional model according to an embodiment of the present invention;

FIG. 15 is a schematic diagram of the complementation of the minimum angle method according to an embodiment of the present invention;

FIG. 16 is a schematic view of a first center point location and a closed fourth crown three-dimensional model according to an embodiment of the present invention;

FIG. 17 is a schematic view of a fifth three-dimensional model of a dental crown according to an embodiment of the present invention;

FIG. 18 is a schematic view of a fifth three-dimensional model of a crown obtained after ellipse fitting according to an embodiment of the present invention;

FIG. 19 is a schematic view of an original dental three-dimensional model and a complete dental crown three-dimensional model contained therein according to an embodiment of the present invention;

fig. 20 is a schematic diagram of hole completion information according to an embodiment of the present invention;

FIG. 21 is a schematic diagram of determining hole completion information according to an embodiment of the present invention;

Reference numerals: 10. an electronic device; 101. a processor; 102. a storage medium.

Detailed Description

In order to describe the possible application scenarios, technical principles, practical embodiments, and the like of the present application in detail, the following description is made with reference to the specific embodiments and the accompanying drawings. The embodiments described herein are only for more clearly illustrating the technical aspects of the present application, and thus are only exemplary and not intended to limit the scope of the present application.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of the phrase "in various places in the specification are not necessarily all referring to the same embodiment, nor are they particularly limited to independence or relevance from other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment may be combined in any manner to form a corresponding implementable technical solution.

Unless defined otherwise, technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains; the use of related terms herein is for the purpose of describing particular embodiments only and is not intended to limit the application.

In the description of the present application, the term "and/or" is a representation for describing a logical relationship between objects, which means that three relationships may exist, for example a and/or B, representing: there are three cases, a, B, and both a and B. In addition, the character "/" herein generally indicates that the front-to-back associated object is an "or" logical relationship.

In the present application, terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual number, order, or sequence of such entities or operations.

Without further limitation, the use of the terms "comprising," "including," "having," or other like terms in this specification is intended to cover a non-exclusive inclusion, such that a process, method, or article of manufacture that comprises a list of elements does not include additional elements but may include other elements not expressly listed or inherent to such process, method, or article of manufacture.

As in the understanding of "review guidelines," the expressions "greater than", "less than", "exceeding" and the like are understood to exclude this number in the present application; the expressions "above", "below", "within" and the like are understood to include this number. Furthermore, in the description of embodiments of the present application, the meaning of "a plurality of" is two or more (including two), and similarly, the expression "a plurality of" is also to be understood as such, for example, "a plurality of" and the like, unless specifically defined otherwise.

In a first aspect, as shown in fig. 1, the present application provides a method for supplementing a base of a three-dimensional model of a dental crown, the three-dimensional model of a dental crown being formed by splicing a plurality of patches of preset shapes, the method comprising the steps of:

In step S1, a non-manifold vertex refers to a vertex whose configuration of the edge or face connected to the vertex does not conform to the local euclidean properties of the manifold. Non-manifold vertices are typically found in several situations: (1) the connection of edges exceeds two faces: in a typical 2-manifold grid, each edge should be shared by exactly two faces. If an edge is shared by three or more faces, both endpoints of the edge are non-manifold vertices. (2) isolated vertices: if a vertex is not part of any edge or face, it is also considered non-manifold because it does not meet the local continuity requirements of the manifold. (3) vertices connecting different elements: a vertex is also considered non-manifold if it connects to both a closed surface and an open boundary. One example is where two separate surfaces are connected by a common vertex.

Non-manifold sides refer to those sides that connect more than two faces. In a standard manifold grid, each edge should be shared by exactly two faces. The presence of non-manifold edges breaks the simple continuity of the mesh, resulting in a complex topology on that edge. For example: an edge is non-manifold if it is shared by three or more faces. For example, a side which is present in a closed loop but is not completely surrounded by two faces is also regarded as non-manifold.

Non-manifold surfaces are those surfaces that do not form a simple continuous structure in the mold. This typically involves a way of connecting the faces such that the set of faces cannot be mapped smoothly into a two-dimensional plane or three-dimensional space within the local vicinity of any point. Non-manifold facets may occur where multiple independent lattice structures intersect without clear demarcation. A face may also be considered non-manifold, for example, if the boundary of the face contains non-manifold edges, or the vertices of the face contain non-manifold vertices. For another example, if a collection of facets are interspersed or connected in a complex manner in space, a continuous surface cannot be defined, and the facets are also considered non-manifold.

Specifically, non-manifold geometric elements (including non-manifold vertex, edge, surface, etc. information) of the three-dimensional model of the crown may be found using an algorithm (Visual and Computer Graphics Library) from an open source vcg library, and removed from the three-dimensional model of the crown corresponding to a single tooth after the finding.

The steps of removing and calculating the non-manifold vertexes, edges and faces are as follows: each triangular surface patch in the crown three-dimensional model corresponding to the single tooth is traversed circularly, for each vertex on each triangular surface patch, the number of the shared surfaces of each vertex is counted, if the number of the shared surfaces exceeds two, the current vertex is a non-manifold vertex, and the current vertex and the edge corresponding to the vertex are deleted; and circulating each triangular patch in the crown three-dimensional model corresponding to the single tooth, checking whether three sides of each triangular patch are manifold, if one side is not manifold, indicating that the current triangular patch is a non-manifold patch, and deleting the current triangular patch from the crown three-dimensional model corresponding to the single tooth. The original crown three-dimensional model (containing non-popular geometric elements) and the first crown three-dimensional model obtained after removal of non-manifold geometric elements are shown in fig. 9.

In step S2, the smoothing algorithm may be selected from a laplace smoothing algorithm, a curvature-based smoothing algorithm, taubin smoothing algorithm, and an HC laplace smoothing algorithm. Preferably, the smoothing algorithm is a laplace smoothing algorithm. The Laplace smoothing algorithm firstly takes a certain vertex in the triangular mesh as a center, acquires a first-order neighborhood structure formed by the vertex, an adjacent vertex and an edge, then moves the vertex to the average position of the adjacent vertex, and sequentially traverses all the vertices until all the vertices move to the corresponding average positions. By performing smoothing treatment on all the patches at the edge positions of the first dental crown three-dimensional model and iterating for a plurality of times, the edge of the obtained second dental crown three-dimensional model can be smoother, a better denoising effect is presented, and the obtained second dental crown three-dimensional model is shown in fig. 10.

In step S3, in the original dental three-dimensional model, there may or may not be an abutment point between the dental crown three-dimensional model and its neighboring dental crown three-dimensional model, and when there is an abutment point, the side edges of two teeth are indicated to be close together, and only after identifying the portion of the abutment point, the corresponding area is complemented, so that the subsequently generated base can more fully reflect the original structure of the teeth. The method comprises the steps of firstly reading a first adjacent point list of a currently processed dental crown three-dimensional model in an original dental jaw three-dimensional model, then calculating a second adjacent point list according to the first adjacent point list (each original first adjacent point can find a second adjacent point corresponding to the edge position of the second dental crown three-dimensional model obtained by smoothing the first adjacent point), and then completing the dental crown three-dimensional model based on the second adjacent point. The distribution of the first abutment points in the original adjacent crown three-dimensional model and its partial detail view are shown in fig. 11, the edge of the second crown three-dimensional model and its partial detail view are shown in fig. 12, and the distribution of the second abutment points on the second crown three-dimensional model and its partial detail view are shown in fig. 13.

In step S4, after the position distribution of all the second neighboring points is determined, the second crown three-dimensional model may be completed with the positions of all the second neighboring points as edges and the patches with the preset shapes as units, so as to obtain a third crown three-dimensional model. The three-dimensional model of the crown obtained after the abutment surface is completed is shown in fig. 14.

In step S5, the tooth axis direction corresponding to each tooth may be a preset direction, and may be determined, for example, by the following manner: calculating the center point positions corresponding to all edge points at the bottom of the dental crown model, connecting the center point positions with the top points of the lowest tooth root part of the current dental crown model, and taking the direction of connecting lines of the center point positions and the top points as the tooth axis direction corresponding to the current dental crown model. The first preset distance can be set according to actual needs, and only the fact that after the center point of the bottom edge moves by the first preset distance, the connecting line of the bottom edge point and the moved center point can be compared with the same point is guaranteed. A schematic diagram of the first center point position and the closed fourth crown three-dimensional model is shown in fig. 16, and in fig. 16, a point O is the position of the first center point.

In step S6, the shape of the cut plane may be circular, elliptical, rectangular or other custom shape. The distance between the cutting position and the lowest edge point of the bottom of the three-dimensional model of the dental crown is preferably within a preset height range, so that the overall height of the fifth three-dimensional model of the dental crown corresponding to each tooth is almost the same, and the overall uniformity and the aesthetic degree of the three-dimensional model of the dental crown are improved. The fifth crown three-dimensional model obtained after the base is completed is shown in fig. 17.

According to the scheme, when the base corresponding to the dental crown three-dimensional model is generated, the distribution condition of the edge adjacent points of the original dental crown model and the adjacent dental crown model is considered, the corresponding second adjacent point list is generated based on the first adjacent point list, and then the base is generated after the dental crown three-dimensional model is complemented to a certain extent according to the distribution of the second adjacent points, so that the complemented base can better reflect the original tooth structure, and the quality of the dental crown three-dimensional model after the base is complemented is improved.

As shown in fig. 2, in some embodiments, the first list of adjacencies is derived according to the following:

If the judgment result of the step S21 is yes, the step S22 is entered to judge whether an adjacent point exists between the current dental crown three-dimensional model and the adjacent dental crown three-dimensional model;

If the judgment result of the step S21 is no, the step S23 is entered to skip the current three-dimensional model of the dental crown, and the step S23 may be entered to the step S21 after the step S23 is again judged for the next three-dimensional model of the dental crown;

If the judgment result of the step S22 is yes, the step S24 is entered to record the coordinate positions of the current neighboring points, the step S24 may be followed by the step S25 to judge whether the three-dimensional model of the dental crown is completely traversed, and if the step S25 is yes, the step S26 is entered to obtain a first neighboring point list corresponding to the current three-dimensional model of the dental crown according to the coordinate positions of all the recorded neighboring points; if the judgment result of the step S25 is no, the step S27 is entered to acquire the next three-dimensional model of the dental crown, and the step S21 can be executed again after the step S27;

if the result of the determination in step S22 is no, the process proceeds to step S23, where the current three-dimensional model of the dental crown is skipped, and the determination is performed again for the next three-dimensional model of the dental crown, and step S21 may be performed after step S23.

By the scheme, whether corresponding adjacent points exist in each dental crown three-dimensional model in the original dental jaw three-dimensional model or not can be combed in advance, if so, the adjacent points are corresponding, and the adjacent points and corresponding dental crown three-dimensional model identifications (such as numbers, file names and the like) are mapped and stored, so that the subsequent calling is convenient.

As shown in fig. 3, in some embodiments, whether there is an abutment point between the current crown three-dimensional model and the abutment crown three-dimensional model is determined according to the following manner:

Firstly, step S301 is carried out to extract edge points of a current dental crown three-dimensional model and edge points corresponding to adjacent dental crown three-dimensional models;

Step S302 is carried out, wherein a k-d tree is constructed for the edge points of the current dental crown three-dimensional model, and whether edge points with the distance within a first preset distance error range from the edge points of the current dental crown three-dimensional model exist in the edge points of the adjacent dental crown three-dimensional model or not is calculated in a traversing mode one by one;

If so, the step S303 is carried out, and an adjacent point exists between the current dental crown three-dimensional model and the adjacent dental crown three-dimensional model, otherwise, the step S304 is carried out, and no adjacent point exists between the current dental crown three-dimensional model and the adjacent dental crown three-dimensional model.

In this embodiment, a K-D Tree (K-Dimension Tree) is a data structure for organizing points in a K-dimensional space. It is particularly suitable for multidimensional searches and nearest neighbor searches. The k-d tree forms a nested axis pair Ji Chao rectangle by recursively partitioning the space along alternating axes. The basic working principle of the k-d tree is as follows:

In constructing a K-d tree, one starts with a set of points in a K-dimensional space. During construction, the space is recursively divided along alternating axes. Each step selects a dimension (axis) in which points are divided into two subsets according to their position. Segmentation continues until each subset contains only a small number of points, or a specified depth is reached.

After construction is complete, various types of searches may be performed, including: nearest neighbor searches (given a query point, find the closest point to the query point in the tree), range searches (find all points within a specified distance (radius) from the given query point), k nearest neighbor searches (find k closest points to the query point), and so on.

In this embodiment, the magnitude of the first preset distance error range may be set according to actual needs, for example, the range may be set to [0,1] mm.

By the scheme, whether the adjacent point exists between the current dental crown three-dimensional model and the adjacent dental crown three-dimensional model can be judged, and the adjacent point and the current dental crown three-dimensional model are mapped and stored so as to facilitate subsequent call processing calculation and restore the original structure of the tooth better.

As shown in fig. 4, in some embodiments, each crown three-dimensional model file in the original dental three-dimensional model is named according to whether it is continuous; the step S1 comprises the following steps:

Firstly, step S401 is carried out to acquire a first file name of a current dental crown three-dimensional model;

Step S402 is then entered to obtain a second file name of the three-dimensional model of the dental crown located on the left side of the current three-dimensional model of the dental crown, and/or to obtain a third file name of the three-dimensional model of the dental crown located on the right side of the current three-dimensional model of the dental crown;

Step S403 is then performed to determine whether the first file name and the second file name are consecutive, and/or whether the first file name and the third file name are consecutive.

In short, each crown three-dimensional model file can be named according to a set rule in advance, and then whether the current crown three-dimensional model is adjacent to the crown three-dimensional model on the left or the right can be deduced based on whether the names of the crown three-dimensional model files are continuous, so that the calculation is simplified.

As shown in fig. 5, in some embodiments, step S4 includes:

Firstly, step S501 is carried out, the included angle of two adjacent sides corresponding to each second adjacent point is calculated in sequence, the second adjacent point with the smallest included angle is found, and the number of patches with preset shapes which need to be increased is determined;

step S502 is then entered to update the edge point information of the second crown three-dimensional model with the corresponding number of patches, find out the edge point with the minimum next included angle based on the edge point information of the current second crown three-dimensional model, and determine the number of patches with preset shapes to be added based on the newly found edge point with the minimum next included angle;

and then, the step S503 is carried out to repeat the step S502 until the boundary repair of the second dental crown three-dimensional model is completed, and a third dental crown three-dimensional model is obtained.

Preferably, the preset-shaped dough sheet is a triangular dough sheet; the determining the number of preset shaped patches to be added includes:

As shown in fig. 15, when traversing edge points each time, the included angle of two adjacent edges corresponding to each edge point can be confirmed, the edge point with the smallest included angle can be found, and the number of triangular patches required to be increased is determined to be complemented. For example, in fig. 15 (a), the angle adb is the smallest angle, and the triangular patches can be completed by connecting the point a and the point b, and the distance between the points ab is relatively long, so that the triangular patches can be completed by adding 2 triangular patches, specifically adding the triangular patches ade and the triangular patches bde. After the first completion, the vertex of the triangular face piece at the edge of the three-dimensional model of the dental crown has become abc, and if the calculated angle abc is the smallest included angle, the triangular face piece can be completed through the connection point a and the point c, and because the distance between ac is relatively long, the triangular face pieces can be completed through adding 2 triangular face pieces, in particular adding the triangular face pieces abf and the triangular face pieces fbc. In this way, after the step S502 is continuously performed for several times, the boundary repairing of the second dental crown three-dimensional model can be implemented, and the third dental crown three-dimensional model is obtained.

In some embodiments, said using the plane to transversely cut the fourth crown three-dimensional model to obtain a base-completed fifth crown three-dimensional model comprises: and performing ellipse fitting on the cut cross section edge points, and fitting the cross section into an ellipse shape to obtain a fifth dental crown three-dimensional model.

As shown in fig. 6, the elliptical fitting of the cut cross-sectional edge points includes:

Firstly, entering a step S601 to calculate the center points of all edge points of the cut cross section, carrying out centering treatment on all edge points of the cross section, calculating covariance matrixes of the edge points after the centering treatment, and solving eigenvalues and eigenvectors of the covariance matrixes so as to determine the major axis and the minor axis of an ellipse;

Step S602 is then carried out to sort the characteristic values, two-dimensional projection is carried out on the first two principal components, ellipse fitting is carried out on a two-dimensional plane, and the fitted ellipse is converted back to ellipse point coordinates in a three-dimensional space according to parameters of the fitted ellipse on the two-dimensional plane;

And then, step S603 is performed to align the coordinates of the elliptical points with the edge points of the cross section after the original cutting, and sequentially replace the edge points of the cross section after the original cutting with the coordinates of the elliptical points.

In other embodiments, when optimizing the cut three-dimensional model of the crown, in addition to elliptical fitting of the cross-sectional edge points, smoothing and thinning of the side edges of the base may be included, so that the surface of the base is smoother, and the optimized three-dimensional model of the fifth crown is shown in fig. 18.

In some embodiments, before smoothing the edge of the first crown three-dimensional model, the method further comprises the steps of: and sequentially judging whether each facial piece in the first dental crown three-dimensional model is a raised edge facial piece, and if so, removing the raised edge facial piece from the first dental crown three-dimensional model.

The edge-warped dough sheet is determined according to the following mode:

Or the edge-warped dough sheet is determined according to the following mode:

In short, by removing the edge-warped surface patches and then performing smoothing treatment, the edge of the dental crown three-dimensional model can be smoother, and the influence of noise surface patches is reduced. Judging the edge-warped surface piece mainly considers two factors, namely, the included angle between the normal vector of the current surface piece and the normal vector average value of the peripheral surface piece, if the included angle between the normal vector average value of the peripheral surface piece exceeds the preset included angle, the current surface piece is tilted compared with the peripheral surface piece, and the second factor is the Di Jie Tesla distance between the edge surface pieces closest to the current surface piece, if the distance is larger, the current surface piece is likely to be positioned in the middle part of the dental crown three-dimensional model rather than at the edge position, and the surface piece is kept for avoiding the normal surface piece from being wrongly removed. The two considered judging orders are not limited, and the dijkstra distance can be judged after the normal vector included angle is judged, or the normal vector included angle can be judged after the dijkstra distance is judged.

The normal vector of each patch may be the average value of the normal vectors of the vertices included in each patch, and taking a patch as a triangular patch as an example, the normal vector corresponding to a certain patch is the average value of three normal vectors of the vertices. The peripheral panels corresponding to a certain panel may be all panels having a common vertex with the certain panel, or may be all panels having a common side with the panel. The normal vector of the vertex is calculated as follows: and fitting a plane by using all vertexes around a certain vertex, and then taking the normal vector of the fitted plane as the normal vector corresponding to the vertex. In order to facilitate subsequent invocation of the normal vector of each patch, after the normal vector of each patch is calculated each time, the normal vector of each patch and the center point coordinate of the patch can be mapped and stored, so that the normal vector corresponding to each patch can be conveniently indexed to participate in calculation.

Dijkstra distance, also known as Dijkstra's algorithm, is an algorithm for finding the shortest path from a starting point to a target node in a weighted graph. And starting from the initial node, gradually expanding and searching outwards, selecting the neighbor node with the smallest weight on the current path each time, and updating the shortest distance from the initial point to each node. By iterating this process until the shortest path to the target node is found. As used herein, dijkstra distance refers to a distance between a preset coordinate point of a certain facial patch and a preset coordinate point in a facial patch located closest to and at an edge position of the first crown three-dimensional model.

In this embodiment, the preset coordinate point of the patch may be a certain vertex or center point of the patch, or may be any point preset in the patch area. The size of the preset included angle and the size of the preset distance can be set according to actual needs.

According to the scheme, the difference between the normal vector values of the triangular face piece with the tilted edge and the normal triangular face piece around is considered, and the Di Jie Tesla distance is added to carry out constraint, so that the triangular tilted edge at the edge of the three-dimensional model of the dental crown can be accurately removed, meanwhile, the triangular face piece in the middle of the three-dimensional model of the dental crown is prevented from being removed by mistake, and the denoising effect is improved.

In some embodiments, the method further comprises: s7: judging whether a cavity area exists in the fifth dental crown three-dimensional model, if so, determining cavity filling information according to the coordinate position of the cavity area, extracting the cavity filling information from the original dental jaw three-dimensional model, and combining the cavity filling information with the fifth dental crown three-dimensional model to obtain a sixth dental crown three-dimensional model.

As shown in fig. 7, the determining the hole filling information according to the coordinate position of the hole area, and extracting the hole filling information from the original dental three-dimensional model includes:

As shown in fig. 19, fig. 19 (a) on the left is a schematic view of an original dental three-dimensional model, fig. 19 (b) on the right is a schematic view of a complete dental crown three-dimensional model, and it is easy to see that the original dental three-dimensional model includes a complete dental crown three-dimensional model of a plurality of teeth, and the dental crown three-dimensional model corresponding to each tooth does not have a cavity area, but in the process of cutting the dental crown three-dimensional model of a plurality of individual teeth from the dental jaw three-dimensional model and performing non-popular geometric elements on the dental crown three-dimensional model of an individual tooth, the algorithm is unlikely to be perfect, so that a cavity area still exists in a dental crown portion above the base of the finally obtained fifth dental crown three-dimensional model, and thus the cavity area needs to be completed.

As shown in fig. 20, fig. 20 (a) on the left is a schematic diagram of the position of a cavity area in an original dental three-dimensional model (denoted by A1) in a crown three-dimensional model of a certain tooth (for example, a crown three-dimensional model obtained by processing a tooth a in fig. 19 (a)), and fig. 20 (b) on the right is a schematic diagram of the distribution of center points corresponding to each of the patches in the original dental three-dimensional model. By traversing whether the two-dimensional coordinates of the center point corresponding to each patch in the original dental three-dimensional model are located in the polygonal region, the cavity completion information corresponding to the current cavity region can be found out from the original dental three-dimensional model, namely, the vertex coordinate positions of the patches in the original dental three-dimensional model of the cavity region are screened out, and the region (such as the B1 region in the fig. 20 (B)) surrounded by the vertices of the patches is extracted to complete the cavity region.

As shown in fig. 21, the present application determines whether the two-dimensional coordinates of the center point of a certain patch are located inside the polygonal area by using a ray method, which is specifically as follows: calculating the number N of intersection points of the ray and the boundary of the polygonal area by emitting a ray from the central point of a certain face piece, judging whether N is an odd number or an even number, and if the N is an odd number, indicating that the central point of the current face piece is positioned in the polygonal area; if N is even, it indicates that the center point of the current patch is located outside the polygonal area.

In a second aspect, the present invention also provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements a method for base replenishment of a three-dimensional model of a dental crown according to the first aspect of the present invention.

Wherein the computer readable storage medium may be volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory.

The non-volatile Memory may be a Read Only Memory (ROM), a programmable Read Only Memory (PROM, programmable Read Only Memory), an erasable programmable Read Only Memory (EPROM, erasable Programmable Read Only Memory), an electrically erasable programmable Read Only Memory (EEPROM, ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY), a magnetic random access Memory (FRAM, ferromagnetic random access Memory), a Flash Memory (Flash Memory), a magnetic surface Memory, an optical disk, or a compact disk Read Only (CD ROM, compact Disc Read Only Memory); the magnetic surface memory may be a disk memory or a tape memory.

The volatile memory may be a random access memory (RAM, random Access Memory) which acts as an external cache. By way of example, and not limitation, many forms of RAM are available, such as static random access memory (SRAM, static Random Access Memory), synchronous static random access memory (SSRAM, synchronous Static Random Access Memory), dynamic random access memory (DRAM, dynamic Random Access Memory), synchronous dynamic random access memory (SDRAM, synchronous Dynamic Random Access Memory), double data rate synchronous dynamic random access memory (ddr SDRAM, double Data Rate Synchronous Dynamic Random Access Memory), enhanced synchronous dynamic random access memory (ESDRAM, enhanced Synchronous Dynamic Random Access Memory), synchronous link dynamic random access memory (SLDRAM, syncLink Dynamic Random Access Memory), direct memory bus random access memory (DRRAM, direct Rambus Random Access Memory). The computer-readable storage media described in connection with the embodiments of the present invention are intended to comprise these and any other suitable types of memory.

As shown in fig. 8, in a third aspect, the present invention provides an electronic device 10, including a processor 101 and a storage medium 102, where a computer program is stored, the computer program, when executed by the processor, implements a method of supplementing a base of a three-dimensional model of a dental crown according to the first aspect of the present invention.

In some embodiments, the Processor may be implemented in software, hardware, firmware, or a combination thereof, and may use at least one of a Circuit, a single or multiple Application-specific integrated Circuit (ASIC), a digital signal Processor (DIGITAL SIGNAL Processor, DSP), a digital signal processing device (DIGITAL SIGNAL Processing Device, DSPD), a programmable logic device (Programmable Logic Device, PLD), a field programmable gate array (Field Programmable GATE ARRAY, FPGA), a central Processor (Central Processing Unit, CPU), a controller, a microcontroller, a microprocessor, so that the Processor may perform some or all of the steps in the method of supplementing the base of the dental crown three-dimensional model, or any combination of the steps therein, in various embodiments of the application.

Finally, it should be noted that, although the embodiments have been described in the text and the drawings, the scope of the application is not limited thereby. The technical scheme generated by replacing or modifying the equivalent structure or equivalent flow by utilizing the content recorded in the text and the drawings of the specification based on the essential idea of the application, and the technical scheme of the embodiment directly or indirectly implemented in other related technical fields are included in the patent protection scope of the application.

Claims

1. A method for supplementing a base of a three-dimensional model of a dental crown, wherein the three-dimensional model of a dental crown is formed by splicing a plurality of patches of preset shapes, the method comprising the steps of:

2. The method of base replenishment of a three-dimensional model of a dental crown according to claim 1, wherein the first list of abutment points is obtained according to the following manner:

3. The base filling method of a three-dimensional model of dental crowns according to claim 2, wherein each of the three-dimensional model files of dental crowns in the original three-dimensional model of dental jaw is named according to whether or not it is continuous;

the step S1 comprises the following steps:

Acquiring a first file name of a current dental crown three-dimensional model;

4. The method for filling the base of the three-dimensional model of dental crown according to claim 1, wherein the step S4 comprises:

5. The method for filling a base of a three-dimensional model of a dental crown of claim 4, wherein the pre-shaped face piece is a triangular face piece;

The determining the number of preset shaped patches to be added includes:

6. The method for filling a base into a three-dimensional model of a dental crown according to claim 1, wherein said transversely cutting the fourth three-dimensional model of a dental crown with the plane to obtain a fifth three-dimensional model of a dental crown with the base filling comprises:

7. The method for filling the base of the three-dimensional model of dental crowns according to claim 1, further comprising the steps of, before smoothing the edges of the first three-dimensional model of dental crowns:

the edge-warped dough sheet is determined according to the following mode:

Or the edge-warped dough sheet is determined according to the following mode:

8. The method for base replenishment of a three-dimensional model of a dental crown of claim 1, further comprising:

s7: judging whether a cavity area exists in the fifth dental crown three-dimensional model, if so, determining cavity filling information according to the coordinate position of the cavity area, extracting the cavity filling information from the original dental jaw three-dimensional model, and combining the cavity filling information with the fifth dental crown three-dimensional model to obtain a sixth dental crown three-dimensional model;

9. A computer-readable storage medium, on which a computer program is stored, characterized in that the program, when executed by a processor, implements a method for base replenishment of a three-dimensional model of a dental crown as claimed in any one of claims 1 to 8.

10. An electronic device having stored thereon a computer program comprising a processor and a storage medium having stored thereon a computer program which, when executed by the processor, implements a method for base replenishment of a dental crown three-dimensional model as defined in any one of claims 1 to 8.