Method and electronic equipment for identifying tooth FA point, accessory pasting position and tooth torque angle

Abstract

The invention relates to the technical field of orthodontic digital design, and discloses a method and electronic equipment for identifying a tooth FA point and an accessory pasting position and confirming a tooth torque angle, and the method for identifying the tooth FA point comprises the following steps: obtaining a three-dimensional tooth jaw digital model which comprises a series of three-dimensional tooth digital models; constructing a first section of each three-dimensional tooth digital model, wherein the first section of the reference point of the pasting surface is a plane which passes through the tooth center and is perpendicular to the tooth mesial and distal axis of the reference point of the pasting surface; calculating the FACC axis of a certain three-dimensional tooth digital model; the method comprises the following steps: intersecting a reference point first cross section of a pasting surface with a reference point three-dimensional tooth digital model of the pasting surface to obtain an intersecting line; selecting one section of the dental crown part on the lip-cheek side surface on the datum point intersecting line of the pasting surface as the FACC axis of the tooth; and selecting the midpoint on the axis of the datum point FACC of the pasting surface as the tooth FA point. The calculation is simple and convenient, and the obtained position of the FA point is accurate, so that the reference data in the digital design is more accurate.

Description

Technical Field

[0001] This invention relates to the field of orthodontic digital design technology, and in particular to a method and electronic device for identifying the FA point of a tooth, the attachment position, and confirming the tooth torque angle. Background Technology

[0002] There are two main types of commonly used orthodontic appliances: fixed appliances that use brackets bonded to the tooth surface and archwires for correction, and invisible appliances made of safe, elastic, transparent polymer materials. With the rapid development of computer technology, the design of orthodontic appliances increasingly relies on computer technology. For example, in orthodontic treatment using shell-shaped braces, computers are used to identify tooth features and positions, such as determining the placement of brackets and other attachments at the FA points, or observing the alignment of teeth.

[0003] Currently, FA points are mainly identified by manual marking or by neural network models. However, manual methods are inefficient and inaccurate, affecting the accuracy of subsequent accessory placement. Neural network identification requires a large amount of data in the early stages, which is very costly and poses a high barrier to entry for small-scale orthodontic design companies. Summary of the Invention

[0004] The purpose of this invention is to provide a method and electronic device for identifying the FA point of a tooth, the attachment position, and confirming the tooth torque angle, which can reduce costs while ensuring the accuracy of FA point identification.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a method for identifying FA points of teeth, comprising: acquiring a three-dimensional digital model of the jaw, including a series of three-dimensional digital models of teeth; constructing a first cross section for each three-dimensional digital model of teeth, the first cross section being a plane passing through the center of the tooth and perpendicular to the mesial and distal axes of the tooth; calculating the FACC axis of a certain three-dimensional digital model of teeth; comprising: intersecting the first cross section with the three-dimensional digital model of teeth to obtain an intersection line; selecting a segment of the upper crown portion on the labial and buccal side of the intersection line as the FACC axis of the tooth; and selecting the midpoint on the FACC axis as the FA point of the tooth.

[0006] Compared with the prior art, the embodiments of the present invention utilize the geometric calculation of the digital model to obtain the FACC axis by taking the intersection of the first cross section and the three-dimensional tooth model. The first cross section is a plane passing through the center of the tooth and perpendicular to the mesial and distal axes of the tooth, thereby obtaining the position of the FA point. The calculation is simple and the obtained position of the FA point is accurate, so that the reference data in digital design is more accurate.

[0007] Optionally, the step of intersecting the first cross section with the three-dimensional digital tooth model to obtain the intersection line includes: calculating the intersection point of the first cross section and the three-dimensional digital tooth model using an explicit calculation method or an implicit calculation method; collecting all intersection points to form an intersection point set, and using the intersection point set to represent the intersection line.

[0008] Optionally, an explicit calculation method is used to calculate the intersection points of the first cross section and the three-dimensional digital tooth model, including: establishing a first plane equation for the first cross section; calculating the function values ​​of each vertex in the three-dimensional digital tooth model using the first plane equation; selecting triangular facets in the three-dimensional digital tooth model that intersect with the first cross section based on the calculation results; wherein the selected triangular facets satisfy that the product of at least two of the function values ​​of their three vertices is less than or equal to 0; calculating two intersection points between each selected triangular facet and the first cross section; the set of all intersection points includes: the set of all intersection points between the selected triangular facets and the first cross section. Since the sign of the function value of each vertex coordinate in the first plane equation is used to characterize the relative positional relationship between the vertex and the plane after the explicit calculation method calculates the function value of each vertex coordinate, only simple function calculation is needed to confirm the relative positional relationship between the vertex and the plane, making the confirmation of the positional relationship not only accurate but also simple and fast.

[0009] Optionally, the intersection line obtained by the intersection of the first cross section and the three-dimensional tooth digital model is calculated using an implicit computation method, including: calculating the signed distance from each vertex in the three-dimensional tooth digital model to the first cross section; filtering the mesh edges that intersect with the first cross section based on the signed distances corresponding to each vertex; wherein the filtered mesh edges satisfy that the product of the signed distances of their two vertices is less than or equal to 0; calculating the intersection point of the filtered mesh edge with the first cross section; the set of all intersection points includes: set all the intersection points of the filtered mesh edges with the first cross section.

[0010] Optionally, in calculating the symbolic distance D from each vertex in the three-dimensional tooth digital model to the first cross section, the formula for calculating the symbolic distance D includes:

[0011] D = (PO)·v;

[0012] Where P is any vertex, O is the center point or centroid of the tooth, and v is the mesial-distal axis of the tooth.

[0013] The formula for calculating the intersection point p between the selected mesh edges and the first cross-section includes:

[0014]

[0015] Where D1 and D2 are the signed distances between two vertices of the grid edge, and P1 and P2 are the two vertices of the grid edge.

[0016] Optionally, selecting a segment of the crown portion on the labial / buccal side of the intersection line as the FACC axis of the tooth includes: identifying the incisal midpoint of the tooth; identifying the buccal point from the gingival line of the tooth; and extracting a portion from the intersection line whose height is between the incisal midpoint and the buccal point of the gingival line, as the FACC axis. In this embodiment, the incisal midpoint and the buccal point of the gingival line are used as the upper and lower boundaries for extracting the crown portion, which is simple to calculate and highly versatile.

[0017] Optionally, the midpoint of the incisal edge includes: when the tooth is an incisor, the midpoint of the incisal edge is the midpoint of the incisal edge; when the tooth is a canine, the midpoint of the incisal edge is the cusp point; when the tooth is a premolar, the midpoint of the incisal edge is the buccal cusp point; and when the tooth is a molar, the midpoint of the incisal edge is the midpoint of the buccal cusp.

[0018] Optionally, extracting the portion of the height between the midpoint of the incisal edge and the buccal point of the gingival line from the intersection line includes: defining a first vector from the center point of the tooth to the midpoint of the incisal edge, and a second vector from the starting point to the buccal point of the gingival line; calculating the angle TL between the first vector and the second vector around the mesiodistal axis; selecting a first class of points from the intersection line, wherein the first class of points satisfies: defining a vector V from the starting point to the first class of points, and the angle between the first vector and the vector V around the mesiodistal axis is between 0 and TL; and selecting all first class of points that meet the conditions to form a FACC point set, which represents the FACC axis.

[0019] Optionally, selecting the midpoint on the FACC axis as the FA point of the tooth includes: accumulating the distances between all adjacent points in the FACC point set to obtain the length of the FACC axis, and taking half the length of the FACC axis to obtain the FA point.

[0020] Optionally, constructing a first section of a three-dimensional digital tooth model includes: establishing a local coordinate system for the tooth, including the labiolingual axis and the root-coronal axis of the tooth; and forming the first section using the labiolingual axis and the root-coronal axis. In this embodiment, the data is determined from the local coordinate system of the tooth. Since establishing a local coordinate system is a necessary operation in three-dimensional tooth modeling, directly using data from the local coordinate system helps reduce additional computational load.

[0021] Optionally, establishing the local coordinate system includes: establishing a standard tooth model corresponding to each tooth position number, with each standard tooth model marked with three axes, including the labiolingual axis and the root-crown axis; transforming the standard tooth model using a rigid registration method to align it with the tooth model whose coordinate system needs to be established, and obtaining a registration transformation mapping matrix; wherein, the rigid registration is a registration method that only includes translation and rotation; after applying the registration transformation mapping matrix to the three axes on the standard tooth model, the model is transformed to the three axes on the new tooth model. Establishing the local coordinate system using the three axes of the standard tooth model is more convenient because the standard tooth model and its three axes are existing data, and a simple mapping transformation can be performed directly to obtain the local coordinate system of each tooth.

[0022] An embodiment of the present invention also provides a method for identifying the attachment position, comprising: identifying the FA point of the tooth to which the attachment is to be added based on the above-described method for identifying the FA point of a tooth, and using the FA point as a reference point for the attachment surface.

[0023] In this embodiment, the identified FA point is used as the reference point when attaching the attachment, so that the attachment can accurately apply force to the FA point of the tooth when applying force, thereby improving the force application efficiency of the attachment.

[0024] The embodiments of the present invention also provide a method for confirming the tooth torque angle, comprising: identifying the FACC axis and the FA point of the tooth based on the above-described method for identifying the FA point of the tooth; calculating the tangential vector of the FACC axis at the FA point, projecting this tangential vector into a first cross section to obtain a projection vector; and calculating the angle between the projection vector and the occlusal direction as the torque angle of the tooth.

[0025] In this embodiment, the identified FA point is used to calculate the tooth torque angle. Since the FA point is on the tooth surface, the FACC axis is more explicit than the tooth long axis used in existing tooth torque angle calculations, so it is more direct and accurate in expressing the tooth torque direction.

[0026] Furthermore, embodiments of the present invention also provide an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the above-described method for identifying tooth FA points, or the above-described method for identifying attachment positions, or the above-described method for confirming tooth torque angles. Attached Figure Description

[0027] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0028] Figure 1 This is a flowchart of the method for identifying tooth FA points provided in the first embodiment of this application;

[0029] Figure 2 This is a flowchart of the process of constructing a first cross section in the method for identifying tooth FA points provided in the first embodiment of this application;

[0030] Figure 3 This is a schematic diagram of the method for identifying tooth FA points provided in the first embodiment of this application, which filters points on the intersection line that belong to the FACC axis;

[0031] Figure 4 This is a flowchart illustrating the implicit calculation method used in the method for identifying tooth FA points provided in the second embodiment of this application to calculate the intersection point of the intersection line between the first cross section and the three-dimensional tooth digital model.

[0032] Figure 5 This is a schematic diagram showing the relationship between intersection points and surfaces in the method for identifying tooth FA points provided in the second embodiment of this application;

[0033] Figure 6 This is a schematic diagram of an electronic device provided in the fifth embodiment of this application. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the various embodiments of this invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this invention to facilitate a better understanding of this application. However, the technical solutions claimed in the claims of this application can be implemented even without these technical details and with various variations and modifications based on the following embodiments.

[0035] In embodiments of the present invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings. These terms are primarily for the purpose of better describing the present invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationships; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the present invention according to the specific circumstances.

[0036] The terms "horizontal plane," "coronal plane," and "sagittal plane" mentioned in the various embodiments of this application refer to terms in biomedical anatomy: a horizontal plane (also called a "transverse plane") is a cross-section perpendicular to the vertical axis that divides the human body into upper and lower parts; a coronal plane is a cross-section that longitudinally cuts the human body into anterior and posterior parts along the left and right directions; a sagittal plane is a cross-section that divides the human body into left and right parts, and the left and right cross-sections are called sagittal planes, while cross-sections that are equal on the left and right are called median sagittal planes.

[0037] The inventors of this application discovered in their research on digital design for orthodontic treatment that, in order to utilize computers to identify tooth features and positions, such as confirming the location of FA points for bracket placement, current methods primarily rely on manual marking or neural network models for FA point identification. However, manual methods are inefficient and inaccurate; neural network identification requires a large amount of initial data, resulting in high costs. Therefore, the inventors of this application propose a method for identifying tooth FA points, comprising: acquiring a three-dimensional digital model of the jaw, including a series of three-dimensional digital tooth models; constructing a first cross-section for each three-dimensional digital tooth model, the first cross-section being a plane passing through the center of the tooth and perpendicular to the mesial and distal axes of the tooth; calculating the FACC axis of a certain three-dimensional digital tooth model; including: intersecting the first cross-section with the three-dimensional digital tooth model to obtain an intersection line; selecting a segment of the upper crown portion on the labial and buccal side of the intersection line as the FACC axis of that tooth; and selecting the midpoint of the FACC axis as the FA point of that tooth. By utilizing the geometric calculations of the digital model, the FACC axis is obtained by taking the intersection line of the first cross section and the three-dimensional tooth model. The first cross section is a plane passing through the center of the tooth and perpendicular to the mesial and distal axes of the tooth, thereby obtaining the position of the FA point. The calculation is simple and the obtained position of the FA point is accurate, so that the reference data in digital design is more accurate.

[0038] The following details the implementation of the method for identifying tooth FA points in this application. The following content is only for the convenience of understanding and is not necessary for implementing this solution.

[0039] First, it should be noted that the method for identifying tooth FA points in this embodiment can be implemented through hardware or a combination of computer software and hardware. For hardware implementation, the method for identifying tooth FA points can be implemented through one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, other electronic devices for implementing the function of identifying tooth FA points, or a selection and combination of the above devices.

[0040] The specific process of the method for identifying tooth FA points provided in the first embodiment of the present invention can be as follows: Figure 1 As shown, it specifically includes:

[0041] Step 101: Obtain a three-dimensional digital model of the teeth and jaws.

[0042] Specifically, the acquired three-dimensional dental digital model can be a three-dimensional digital model corresponding to the initial tooth layout, or a three-dimensional digital model corresponding to the current tooth layout when the target tooth layout needs to be reconfirmed during orthodontic treatment, or other three-dimensional dental digital models that need to identify the FA points of teeth. The source of the model is determined as needed and is not limited here.

[0043] In some embodiments, the three-dimensional digital model of the jaw can be obtained by scanning the patient's teeth with an oral scanning device, or by obtaining a plaster model of the teeth through an impression and then scanning to obtain the three-dimensional digital model of the jaw. These methods will not be listed here.

[0044] Specifically, the acquired 3D dental digital model can be a dental mesh model after incisor classification, in which each tooth is an independent model. That is, the acquired 3D dental digital model includes a series of 3D tooth digital models, each marked with a tooth position number for easy subsequent use. In some embodiments, the initial tooth layout is a single jaw row, such as a single mandibular jaw.

[0045] Step 102: Construct the first section of each three-dimensional digital tooth model.

[0046] Specifically, the first cross-section is a plane passing through the center of the tooth and perpendicular to the mesial-distal axis of the tooth. In practical applications, the process of constructing the first cross-section can be as follows: Figure 2 As shown, it specifically includes:

[0047] Step 201: Establish the local coordinate system of the tooth, which includes the labial-lingual axis and the root-crown axis of the tooth.

[0048] Specifically, there are several ways to establish a local coordinate system. For example, one method is to establish the labial-lingual axis, root-crown axis, and mesiodistal axis of the tooth, each centered at the tooth's center point. Other methods include: establishing a standard tooth model corresponding to each tooth position number, with each model labeled with its three axes, including the labial-lingual and root-crown axes; transforming the standard tooth model using rigid registration to align it with the tooth model to be used in the coordinate system, obtaining a registration transformation mapping matrix; where rigid registration is a method involving only translation and rotation; and applying the registration transformation mapping matrix to the three axes of the standard tooth model to transform them onto the new tooth model. Using the three axes of the standard tooth model to establish the local coordinate system is more convenient because the standard tooth model and its axes are existing data; a simple mapping transformation can directly obtain the local coordinate system for each tooth, making calculations easier.

[0049] Step 202: The first cross section is formed by the lip-tongue axis and the root-crown axis.

[0050] After confirming the first section, continue calculating the FACC axis.

[0051] Step 103: Calculate the FACC axis of the three-dimensional digital tooth model.

[0052] Specifically, this includes: intersecting the first section of the three-dimensional digital tooth model of the FA point to be calculated with the three-dimensional digital tooth model to obtain the intersection line.

[0053] In this embodiment, an explicit calculation method is used to calculate the intersection point between the first cross section and the three-dimensional tooth digital model; all intersection points are collected to form an intersection point set, which is used to represent the intersection line.

[0054] In some embodiments, an explicit calculation method is used to calculate the intersection points of the first cross section and the three-dimensional digital tooth model, including: establishing a first plane equation for the first cross section; calculating the function values ​​of each vertex in the three-dimensional digital tooth model using the first plane equation; selecting triangular facets in the three-dimensional digital tooth model that intersect with the first cross section based on the calculation results; wherein the selected triangular facets satisfy the condition that the product of at least two of the function values ​​of their three vertices is less than or equal to 0; calculating two intersection points between each selected triangular facet and the first cross section; the set of all intersection points includes: the set of all intersection points between the selected triangular facets and the first cross section. Since the sign of the function value of each vertex coordinate in the first plane equation is used to characterize the relative positional relationship between the vertex and the plane after the explicit calculation method calculates the function value of each vertex coordinate, only simple function calculation is needed to confirm the relative positional relationship between the vertex and the plane, making the confirmation of the positional relationship not only accurate but also simple and fast.

[0055] Taking a triangular mesh model (V,F) as an example: V represents vertex geometry, and F represents facet geometry. The expression for the first plane equation can be ax + by + cz + d = 0, where x, y, and z are the three components of the spatial coordinates, and a, b, c, and d are constants representing the direction of the first plane. A corresponding function equation is set: f(x,y,z) = ax + by + cz + d. Substituting the three vertices v1, v2, and v3 of the triangular facet into the plane equation, if f(v1), f(v2), and f(v3) have the same sign, it means that points v1, v2, and v3 are on the same side of the plane, and the plane and triangle will not intersect; otherwise, they will intersect. If they intersect, there exists a line segment on the triangular facet that intersects the plane. Traversing all the triangular faces in the model, we check whether they intersect the plane and connect all the obtained line segments end-to-end to obtain a continuous line of intersection.

[0056] In this case, assuming that one side of the triangular facet intersects the plane, and the vertices of this side are located on both sides of the plane, and assuming that there are two vertices, v1 and v2, and f(v1) and f(v2) have opposite signs, the relationship between the line segment v1v2 and the intersection point p of the plane can be expressed as the following expression (1):

[0057] p=λ*v1+(1-λ)*v2; (1)

[0058] Where λ represents the proportion of point p on line segment v1v2, and v1 and v2 are the coordinates of two preset vertices;

[0059] Substitute expression (1) into the plane equation (ax+by+cz+d=0) to solve for λ, and then obtain the position of the intersection point p according to expression (1). If the triangular facet intersects the plane, then the three sides intersect the plane to obtain two intersection points. Collect all the intersection points to obtain the intersection point set {p}, and connect the intersection points to obtain the intersection line segment.

[0060] Step 104: Select a segment of the upper crown portion on the labial / buccal side of the intersection line as the FACC axis of the tooth.

[0061] Specifically, this step may include identifying the midpoint of the incisal edge of the tooth; identifying the buccal point from the gingival line of the tooth; and extracting the portion between the midpoint of the incisal edge and the buccal point of the gingival line from the intersection line as the FACC axis. In this embodiment, the midpoint of the incisal edge and the buccal point of the gingival line are used as the upper and lower boundaries for extracting the crown portion, which is simple to calculate and highly versatile. It should be noted that in this embodiment, the midpoint of the incisal edge can be identified using different methods for different types of teeth, specifically including: when the tooth is an incisor, the midpoint of the incisal edge is the midpoint of the incisal edge; when the tooth is a canine, the midpoint of the incisal edge is the cusp; when the tooth is a premolar, the midpoint of the incisal edge is the buccal cusp; and when the tooth is a molar, the midpoint of the incisal edge is the midpoint of the buccal cusp.

[0062] In some embodiments, a segment of the crown portion on the labial / buccal side of the intersection line can be selected by using the upper and lower boundaries of the crown. In practical applications, other methods can also be used to confirm the upper and lower boundaries, specifically including: defining a first vector from the center point of the tooth to the midpoint of the incisal edge, and a second vector from the starting point to the buccal point on the gingival line; calculating the angle TL between the first vector and the second vector around the mesiodistal axis; selecting a first type of points from the intersection line, wherein the first type of points satisfy: defining a vector V from the starting point to the first type of points, and the angle between the first vector and the vector V around the mesiodistal axis is between 0 and TL; and selecting all first type of points that meet the conditions to form a FACC point set, which represents the FACC axis. Figure 3For example, take the point Pgum on the buccal segment of the gingival line that is closest to the first cross-section. The vector v1 is obtained by connecting the centroid (or centroid point) O of the tooth to Pgum. The vector from the centroid of the tooth to the midpoint of the incisal edge is denoted as v2. The angle TL is the angle of rotation from v2 to v1 around the mesial-distal axis of the tooth. For any point in the point set {p}, the vector v is the vector from the centroid of the tooth to that point. The angle theta is the angle of rotation from v2 to v around the mesial-distal axis of the tooth. If theta ∈ [0, TL], then the point is stored in {p_facc}; otherwise, it is not stored. The resulting point set {p_facc} is the tooth facc point set.

[0063] Step 105: Select the midpoint on the FACC axis as the FA point of the tooth.

[0064] Specifically, the distances between all adjacent points in the FACC point set are summed to obtain the length of the FACC axis, and the FA point is obtained by taking half the length of the FACC axis.

[0065] As can be seen, this embodiment utilizes geometric calculations of the digital model to obtain the FACC axis by taking the intersection of the first cross-section and the three-dimensional tooth model. The first cross-section is a plane passing through the center of the tooth and perpendicular to its mesial and distal axes, thus obtaining the position of the FA point. This method is simple to calculate and the obtained FA point position is accurate, ensuring more accurate baseline data in digital design. Furthermore, this embodiment limits the confirmation to the local coordinate system of the tooth. Since establishing a local coordinate system is a necessary operation when modeling a tooth in three dimensions, directly using data from the local coordinate system helps reduce additional computational load.

[0066] The second embodiment of this application provides a method for identifying the FA point of a tooth. The main difference between this embodiment and the previous embodiment is that the first embodiment uses an explicit calculation method to calculate the intersection of the first cross section and the digital model, while this embodiment uses an implicit calculation method, providing a more flexible calculation method.

[0067] Specifically, the intersection points of the intersection line between the first cross section and the three-dimensional tooth digital model are calculated using an implicit calculation method, such as... Figure 4 As shown, it specifically includes:

[0068] Step 401: Calculate the symbolic distance from each vertex in the three-dimensional tooth digital model to the first cross section.

[0069] Specifically, the formula for calculating the symbolic distance D includes:

[0070] D = (PO)·v;

[0071] Where P is any vertex, O is the center point or centroid of the tooth, and v is the mesial-distal axis of the tooth.

[0072] Step 402: Based on the sign distances of each vertex, filter the mesh edges that intersect with the first cross section; wherein the filtered mesh edges are those whose product of the sign distances of their two vertices is less than or equal to 0.

[0073] Step 403: Calculate the intersection points of the selected mesh edges and the first cross section.

[0074] Specifically, in this step, the formula for calculating the intersection point p includes:

[0075]

[0076] Where D1 and D2 are the signed distances between two vertices of the grid edge, and P1 and P2 are the two vertices of the grid edge.

[0077] It should be noted that after calculating the intersection points of the mesh edges and the first cross section, the set of all intersection points specifically includes all the selected mesh edges and the first cross section, thus obtaining all the intersection points of the first cross section and the digital model.

[0078] It should be noted that, to obtain an ordered set of intersection points {p}, the following methods can be used (e.g. Figure 5 As shown):

[0079] 1) First adopt Figure 4 The intersection point of the first cross section and the three-dimensional tooth digital model is found in the intersection line. The first intersection point p1 of the first cross section and the mesh is found and stored in {p}. The index number of the mesh edge is eInd1, corresponding to the face fInd1.

[0080] 2) Find the indices eInd2_1 and eInd2_2 of the triangle containing this side;

[0081] 3) Adopt Figure 4 The method in the text finds the edge eInd2 that intersects the plane in edges eInd2_1 and eInd2_2, and its intersection point (the second intersection point p2);

[0082] 4) Find the other face fInd2 adjacent to edge eInd2;

[0083] 5) Determine whether fInd2 and fInd1 are the same face;

[0084] 6) If fInd2 and fInd1 are not the same face, then store the intersection point p2 in {p}.

[0085] 7) Repeat steps 2)-4) on face fInd2; otherwise, terminate the loop and return {p}.

[0086] As can be seen, the method for identifying tooth FA points in this embodiment calculates the intersection point of the first cross section and the three-dimensional tooth digital model using an implicit calculation method. Combined with the first embodiment, it can be understood that different calculation methods can be flexibly adopted in practical applications, facilitating the expansion of application scenarios. Furthermore, the {p} obtained in this embodiment is a set of points arranged clockwise or counterclockwise, which facilitates direct connection of the points to the intersection line later, ensuring accuracy.

[0087] The third embodiment of this application provides a method for identifying the attachment placement location, comprising: identifying the FA point of the tooth to which the attachment is to be added based on the above-described method for identifying tooth FA points, and using the FA point as a reference point for the attachment's bonding surface. In this embodiment, the identified FA point is used as a reference point for attachment bonding, which facilitates accurate application of force to the FA point of the tooth when the attachment is applied, thereby improving the force application efficiency of the attachment.

[0088] The fourth embodiment of this application provides a method for confirming the tooth torque angle, comprising: identifying the FACC axis and the FA point of the tooth based on the above-described method for identifying the FA point of the tooth; calculating the tangential vector of the FACC axis at the FA point, projecting this tangential vector into a first cross section to obtain a projection vector; and calculating the angle between the projection vector and the occlusal direction as the torque angle of the tooth. In this embodiment, the identified FA point is used to calculate the tooth torque angle. Since the FA point is on the tooth surface, the FACC axis is more explicit than the tooth long axis used in existing methods for calculating the tooth torque angle, thus providing a more direct and accurate representation of the tooth torque direction.

[0089] Furthermore, it can be understood that during subsequent tooth arrangement, the FA point can also be used to control the tooth torque. Specifically, the buccal-lingual distance between the FA point of each tooth and the midpoint of the incisal edge is calculated to obtain the buccal-lingual distance set; the buccal-lingual distance set is smoothed using Laplacian to obtain the target buccal-lingual distance set; for each tooth, the tooth is rotated around the mesial-distal axis so that the buccal-lingual distance between the FA point and the midpoint of the incisal edge is equal to the target buccal-lingual distance.

[0090] In practical applications, the FACC axis can also be used to control tooth axial tilt. Specifically, since the FACC axis is more intuitive than the long axis in clinical practice, the angle between the projection line of the FACC axis on the sagittal plane and the occlusal direction is calculated to obtain the tooth axial tilt angle. The control process will not be elaborated here.

[0091] It is worth mentioning that the examples above in this application are merely illustrative for ease of understanding and do not constitute a limitation on the technical solutions of this invention.

[0092] The steps of the various methods described above are only for clarity. In practice, they can be combined into one step or some steps can be split into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this patent. Adding insignificant modifications or introducing insignificant designs to the algorithm or process, but without changing the core design of the algorithm and process, are also within the scope of protection of this patent.

[0093] The fifth embodiment of this application relates to an electronic device, such as... Figure 6 As shown, it includes: at least one processor 601; and a memory 602 communicatively connected to the at least one processor 601; wherein the memory 602 stores instructions executable by the at least one processor 601, the instructions being executed by the at least one processor 601 to enable the at least one processor 601 to perform the method for identifying tooth FA points in the first or second embodiment described above, or the method for identifying attachment placement in the third embodiment described above, or the method for confirming tooth torque angle in the fourth embodiment described above.

[0094] The memory and processor are connected via a bus, which can include any number of interconnecting buses and bridges, connecting various circuits of one or more processors and memories. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0095] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0096] Another embodiment of this application relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the method for identifying FA points of teeth in the above-described partial embodiments, or the digital modeling method for dental orthodontic models in the above-described partial embodiments.

[0097] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0098] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. A method of identifying a dental FA point, characterized by, The method comprises the following steps: acquiring a three-dimensional dental model, which comprises a series of three-dimensional tooth models; constructing a first cross section of each three-dimensional tooth model, the first cross section being a plane passing through the center of the tooth and being perpendicular to the mesial-distal axis of the tooth; calculating the FACC axis of a three-dimensional tooth model; which comprises: intersecting the first cross section with the three-dimensional tooth model to obtain an intersection line; selecting a segment of the intersection line on the crown part of the labial-buccal surface as the FACC axis of the tooth; selecting the midpoint of the FACC axis as the FA point of the tooth.

2. The method of identifying a dental FA point according to claim 1, wherein, The step of intersecting the first cross section with the three-dimensional tooth model to obtain an intersection line comprises: calculating the intersection points of the first cross section and the three-dimensional tooth model by using an explicit calculation method or an implicit calculation method; collecting all the intersection points to form an intersection point set, and taking the intersection point set as the representation of the intersection line.

3. The method of identifying a dental FA point according to claim 2, wherein, The step of calculating the intersection points of the first cross section and the three-dimensional tooth model by using an explicit calculation method comprises: establishing a first plane equation of the first cross section; calculating the function values of each vertex in the three-dimensional tooth model by using the first plane equation; selecting the triangular facets of the three-dimensional tooth model that intersect with the first cross section according to the calculation results, wherein the selected triangular facets satisfy that the product of at least two of the function values of the three vertices is less than or equal to 0; calculating two intersection points of each selected triangular facet and the first cross section; the step of collecting all the intersection points comprises: collecting the intersection points of all the selected triangular facets and the first cross section.

4. The method of identifying a dental FA point according to claim 2, wherein, The step of calculating the intersection line of the first cross section and the three-dimensional tooth model by using an implicit calculation method comprises: calculating the signed distances of each vertex in the three-dimensional tooth model to the first cross section; selecting the grid edges that intersect with the first cross section according to the signed distances of the vertices, wherein the selected grid edges satisfy that the product of the signed distances of the two vertices is less than or equal to 0; calculating the intersection points of the selected grid edges and the first cross section; the step of collecting all the intersection points comprises: collecting the intersection points of all the selected grid edges and the first cross section.

5. The method of identifying a dental FA point according to claim 4, wherein, In the step of calculating the signed distances of each vertex in the three-dimensional tooth model to the first cross section, the calculation formula of the signed distance D comprises: D = (P-O)·v; wherein P is any vertex, O is the center point or the gravity center point of the tooth, and v is the mesial-distal axis of the tooth. In the step of calculating the intersection points of the selected grid edges and the first cross section, the calculation formula of the intersection point p comprises: wherein D1 and D2 are the signed distances of the two vertices of the grid edge, and P1 and P2 are the two vertices of the grid edge.

6. The method of identifying a dental FA point according to any one of claims 1-5, wherein, The step of selecting a segment of the intersection line on the crown part of the labial-buccal surface as the FACC axis of the tooth comprises: confirming the midpoint of the incisal edge of the tooth; confirming the buccal point from the gum line of the tooth; cutting out a part from the intersection line, the height of the part being between the midpoint of the incisal edge and the buccal point of the gum line, as the FACC axis.

7. The method of identifying a dental FA point according to claim 6, wherein, The incisal edge midpoint includes: when the tooth is an incisor, the incisal edge midpoint is the midpoint of the incisal edge; when the tooth is a canine, the incisal edge midpoint is the tooth tip point; when the tooth is a premolar, the incisal edge midpoint is the buccal tip point; and when the tooth is a molar, the incisal edge midpoint is the midpoint of the buccal tip.

8. The method of identifying a dental FA point of claim 6, wherein, A portion with a height between the incisal edge midpoint and the buccal side point of the gum line is cut from the intersection line, including: A first vector from the center point of the tooth to the incisal edge midpoint and a second vector from the center point of the tooth to the buccal side point of the gum line are defined, and an included angle TL of the first vector rotating around the mesiodistal axis to the second vector is calculated; First type points are screened from the intersection line, the first type points satisfying: a vector V from the center point to the first type point is defined, and an included angle between the first vector and the vector V rotating around the mesiodistal axis is between 0-TL; All first type points satisfying the condition are collected to form a FACC point set, and the FACC point set is used to represent the FACC axis.

9. The method of identifying a dental FA point according to claim 8, wherein, A midpoint on the FACC axis is selected as the FA point of the tooth, including: the length of the FACC axis is obtained by accumulating the distances between all adjacent points in the FACC point set, and the FA point is obtained by taking half of the length of the FACC axis.

10. The method of identifying a dental FA point according to any one of claims 1-5, wherein, A first cross section of a three-dimensional tooth digital model is constructed, including: A local coordinate system of the tooth is established, including a labial-lingual axis and a root-crown axis of the tooth; The first cross section is formed by the labial-lingual axis and the root-crown axis.

11. The method of identifying a dental FA point according to claim 10, wherein, The local coordinate system is established, including: Standard tooth models corresponding to each tooth number are established, and each standard tooth model is marked with three axes of the tooth, including a labial-lingual axis and a root-crown axis of the tooth; A rigid registration method is used to transform the standard tooth model to align it with the tooth model to be built, and a registration transformation mapping matrix is obtained; wherein the rigid registration is a registration method including only translation and rotation; After the three axes on the standard tooth model are subjected to the registration transformation mapping matrix, the three axes are converted to the three axes on the new tooth model.

12. An attachment position recognition method characterized by, Including: The FA point of the tooth to which the accessory is to be added is identified based on the method for identifying the FA point of the tooth according to any one of claims 1-11, and the FA point is used as a reference point of a pasting surface of the accessory.

13. A method of identifying a tooth torque angle, characterized by, Including: The FACC axis and the FA point of the tooth are identified based on the method for identifying the FA point of the tooth according to any one of claims 1-11; A tangent vector of the FACC axis at the FA point is calculated, the tangent vector is projected into a first cross section to obtain a projection vector, and an included angle between the projection vector and a bite direction is calculated as a torque angle of the tooth. Including:

14. An electronic device, comprising: At least one processor; And A memory connected in communication with the at least one processor; wherein ​ The memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the method of identifying a FA point of a tooth as claimed in any one of claims 1 to 11, or the method of identifying an attachment paste position as claimed in claim 12, or the method of confirming a torque angle of a tooth as claimed in claim 13.

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