Tooth long axis determination method and device, electronic equipment and storage medium

Abstract

The invention discloses a tooth long axis determination method and device, electronic equipment and a storage medium, and the method comprises the steps: obtaining oral cavity cone beam CT data, and segmenting tooth enamel; selecting a plurality of discrete points of the tooth enamel at the glaze cementum boundary of the tooth enamel, and obtaining coordinates of the discrete points; determining a tooth center coordinate and a glazed cementum boundary reference plane according to the coordinate of each discrete point; and determining a tooth long axis based on the tooth body center coordinate and the glazed cementum boundary reference plane. According to the scheme, the long axis of the tooth can be determined, so that the inclination angle and distance information of the tooth relative to the alveolar bone is determined, and reference is provided for oral operations such as implant repair; meanwhile, a three-dimensional digital measurement tooth reference plane and a three-dimensional coordinate system which are high in repeatability and have clinical significance are provided for manual measurement of cone beam CT clinical indexes and AI automatic identification measurement, and a solid theoretical foundation is laid for clinical research in the field of oral medicine AI automation.

Description

Technical Field

[0001] The present invention relates to the technical field of oral medicine, and in particular to a method, device, electronic equipment and storage medium for determining a tooth long axis. Background Art

[0002] The long axis of a tooth is a geometric axis that passes through the tooth longitudinally (crown-root direction) and through the center of the tooth. It is used to describe the characteristics and relationships of teeth during tooth observation and measurement. For example, by determining the three-dimensional coordinate system of each tooth and the long axis of the tooth, the inclination angle and distance of the tooth relative to the alveolar bone can be obtained, providing a reference for oral surgery such as implant restorations and avoiding complications. However, inaccuracies in the long axis of the tooth affect the accuracy of precision oral surgery, especially automated surgery.

[0003] Furthermore, the current recognition and measurement of oral 3D cone-beam CT images lacks a clear and reliable reference system. Measuring techniques often rely on their own experience to qualitatively determine the long axis of the tooth in the 3D reconstructed image as the baseline for measurement. However, this method cannot accurately describe the long axis using mathematical language, suffers from poor repeatability, and makes it impossible to connect different teeth and tooth positions, or to convert or unify them. This has significantly hindered the development of AI-based automated recognition and measurement in dentistry. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a method and device for determining the long axis of a tooth that overcomes the above problems or at least partially solves the above problems.

[0005] According to one aspect of the present invention, a method for determining a tooth's long axis is provided, the method comprising:

[0006] Acquire oral cone-beam CT data and segment the enamel;

[0007] At the cementoenamel junction of the tooth enamel, selecting a plurality of discrete points of the tooth enamel and obtaining the coordinates of each of the discrete points;

[0008] Determine the tooth center coordinates and the cementoenamel junction reference plane according to the coordinates of each discrete point;

[0009] The long axis of the tooth is determined based on the tooth center coordinates and the cementoenamel junction reference plane.

[0010] In some embodiments, acquiring cone-beam CT data and segmenting tooth enamel includes:

[0011] Acquiring oral three-dimensional volume data, wherein the oral three-dimensional volume data is obtained from a cone-beam CT machine;

[0012] Performing three-dimensional reconstruction on the oral three-dimensional volume data to obtain cone-beam CT data;

[0013] The tooth enamel is segmented from the cone-beam CT data, the tooth enamel is binarized, and three-dimensional point cloud data of the segmented tooth enamel is constructed.

[0014] In some embodiments, selecting a plurality of discrete points on the tooth enamel and obtaining the coordinates of each of the discrete points includes:

[0015] At the cementoenamel junction, multiple evenly distributed discrete points are selected, and the three-dimensional coordinate value of each discrete point is obtained and recorded.

[0016] In some embodiments, determining the coordinates of the tooth center according to the coordinates of each discrete point includes:

[0017] The average value of the three-dimensional coordinates of each of the discrete points is calculated, and the coordinates of the tooth center are determined based on the average value.

[0018] In some embodiments, determining the cementoenamel junction reference plane according to the coordinates of each of the discrete points comprises:

[0019] The characteristics of the MP generalized inverse are used to solve the minimum least square solution from each discrete point to the cementoenamel junction reference plane, thereby determining the cementoenamel junction reference plane.

[0020] In some embodiments, utilizing the properties of the MP generalized inverse to solve the minimum least squares solution from each discrete point to the cementoenamel junction reference plane includes:

[0021] Constructing a reference plane equation in functional form and substituting the coordinates of each discrete point into it;

[0022] Obtaining the vector form of the reference plane equation AX=b;

[0023] Determine the MP generalized inverse A of matrix A + ;

[0024] Based on A + The properties of are used to obtain the minimum least squares solution of x, thereby obtaining the enamel-cementum junction reference plane.

[0025] In some embodiments, determining the long axis of the tooth based on the tooth center coordinates and the cementoenamel junction reference plane comprises:

[0026] Determine a perpendicular line passing through the tooth center coordinate and perpendicular to the cementoenamel junction reference plane, and the perpendicular line is the straight line where the long axis of the tooth is located.

[0027] According to another aspect of the present invention, a device for determining a tooth major axis is provided, the device comprising:

[0028] Data acquisition module, which acquires oral cone-beam CT data and segments tooth enamel;

[0029] a coordinate determination module adapted to select a plurality of discrete points of the tooth enamel at the cementoenamel junction of the tooth enamel and obtain the coordinates of each of the discrete points;

[0030] a plane determination module adapted to determine the coordinates of the tooth center and the cementoenamel junction reference plane according to the coordinates of each of the discrete points;

[0031] The tooth long axis determination module is adapted to determine the tooth long axis based on the tooth center coordinates and the cementoenamel junction reference plane.

[0032] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; and a memory arranged to store computer-executable instructions, wherein when the instructions are executed, the processor executes any one of the above-mentioned methods for determining the tooth long axis.

[0033] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores one or more programs, and when the one or more programs are executed by a processor, the method for determining the long axis of a tooth according to any one of the above items is implemented.

[0034] From the above, it can be seen that according to the above technical solution disclosed in the present invention, the long axis of the tooth can be determined, thereby determining the inclination angle and distance information of the tooth relative to the alveolar bone, providing a reference for oral surgery such as implant restoration; at the same time, it also provides a highly repeatable and clinically significant three-dimensional digital measurement tooth reference plane for manual measurement of cone beam CT clinical indicators and AI automated recognition measurement, and determines the three-dimensional coordinate system, laying a solid theoretical foundation for clinical research in the field of AI automation in oral medicine.

[0035] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0037] Figure 1 A schematic flow chart of a method for determining a tooth long axis according to an embodiment of the present invention is shown;

[0038] Figure 2 A schematic diagram showing the relationship between a spatial point, a tooth center, a reference plane, and a tooth long axis according to an embodiment of the present invention;

[0039] Figure 3 A schematic diagram showing the relationship between a spatial point P, a tooth center, and a tooth long axis according to another embodiment of the present invention;

[0040] Figure 4 A schematic structural diagram of a device for determining a tooth long axis according to an embodiment of the present invention is shown;

[0041] Figure 5 A schematic structural diagram of an electronic device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0042] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0043] The main technical concept of the present invention is that the long axis of the tooth is an imaginary axis that passes through the center of the tooth (crown-root direction) and is basically perpendicular to the cementoenamel junction, which also provides a way of thinking for determining the long axis of the tooth. First, the spatial position of the tooth is determined, the center of the tooth is found, and then an axis perpendicular to the cementoenamel junction is drawn through the center of the tooth, and this axis is the long axis of the tooth. Since the cementoenamel junction is not easy to describe quantitatively, it is difficult to use it as a bridge to accurately describe the long axis of the tooth. Therefore, an attempt is made to construct a unique reference plane with the minimum 2-norm with each point on the cementoenamel junction through the tooth sampling information, so as to accurately describe the position of the long axis of the tooth.

[0044] Specifically, Figure 1 The flowchart of a method for determining the long axis of a tooth according to an embodiment of the present invention is shown, and includes the following steps:

[0045] Step S110, acquiring oral cone-beam CT data and segmenting tooth enamel;

[0046] Step S120, selecting a plurality of discrete points of the enamel at the cementoenamel junction of the enamel, and obtaining the coordinates of each of the discrete points; wherein the cementoenamel junction is the boundary connecting the enamel and the cementum;

[0047] Step S130, determining the tooth center coordinates and the cementoenamel junction reference plane according to the coordinates of each discrete point;

[0048] Step S140: determining the long axis of the tooth based on the tooth center coordinates and the cementoenamel junction reference plane.

[0049] The method for determining the long axis of the tooth provided in the above embodiment can determine the angle and distance information of the tooth relative to the alveolar bone through the long axis of the tooth, provide a reference for oral surgery such as implant restoration, and improve the accuracy of the surgery; on the other hand, it also provides highly repeatable three-dimensional digital measurement reference planes and reference axes for manual measurement and AI automated recognition measurement of cone beam CT clinical indicators, determines the three-dimensional coordinate system of the tooth, and lays a solid theoretical foundation for clinical research in the field of AI automation in oral medicine.

[0050] It should be noted that, according to one embodiment of the present invention, the reference plane is obtained by sampling the tooth layer by layer, and obtaining n (n≥3) three-dimensional space points P ({P∈R 3}) is further determined based on the coordinates.

[0051] Determining the tooth three-dimensional coordinate system based on the tooth long axis and the cementoenamel junction reference plane includes:

[0052] 1. Determine the spatial rectangular coordinate system:

[0053] Origin O: Tooth center

[0054] Positive direction of x-axis: select point a farthest from the reference plane from the scattered points, project it onto the reference plane and record it as point a'. The vector is the positive direction of the x-axis;

[0055] Positive direction of y axis: Starting from the positive direction of x axis, the direction vector (j m , k m , -1) is the axis, rotate 90° counterclockwise;

[0056] Positive z-axis direction: parallel to the direction vector (j m , k m , -1).

[0057] 2. Determine the cylindrical coordinate system:

[0058] Origin O: Tooth center

[0059] Azimuth angle 0° ray direction: Select the point a farthest from the reference plane from the scattered points, project it onto the reference plane and record it as point a'. The vector is the direction of the ray with azimuth angle 0°;

[0060] Azimuth angle θ: the counterclockwise rotation angle starting from the 0° azimuth ray;

[0061] Positive z-axis direction: parallel to the direction vector (jm , k m , -1).

[0062] 3. Determine the spherical coordinate system:

[0063] Origin O: Tooth center

[0064] Azimuth angle 0° ray direction: Select the point a farthest from the reference plane from the scattered points, project it onto the reference plane and record it as point a'. The vector is the direction of the ray with azimuth angle 0°;

[0065] Azimuth The angle of rotation in counterclockwise direction from the azimuth angle 0°;

[0066] Elevation angle 0° ray direction: parallel to the direction vector (j m , k m , -1);

[0067] Elevation angle θ: The vertical clockwise rotation angle starting from the ray with an elevation angle of 0°.

[0068] In some embodiments, step S110 of acquiring cone-beam CT data and segmenting tooth enamel specifically includes:

[0069] Acquiring oral three-dimensional volume data, wherein the oral three-dimensional volume data is obtained from a cone-beam CT machine;

[0070] Performing three-dimensional reconstruction on the oral three-dimensional volume data to obtain cone-beam CT data;

[0071] The tooth enamel is segmented from the cone-beam CT data, the tooth enamel is binarized, and three-dimensional point cloud data of the segmented tooth enamel is constructed.

[0072] In some embodiments, selecting multiple discrete points of the tooth enamel in step S120 and obtaining the coordinates of each of the discrete points includes:

[0073] At the cementoenamel junction, multiple evenly distributed discrete points are selected, and the three-dimensional coordinate value of each discrete point is obtained and recorded.

[0074] In some embodiments, determining the tooth center coordinates according to the coordinates of each discrete point in step S130 includes:

[0075] The average value of the three-dimensional coordinates of each of the discrete points is calculated, and the coordinates of the tooth center are determined based on the average value.

[0076] In some embodiments, determining the cementoenamel junction reference plane according to the coordinates of each discrete point in step S130 includes:

[0077] The characteristics of the MP generalized inverse are used to solve the minimum least square solution from each discrete point to the cementoenamel junction reference plane, thereby determining the cementoenamel junction reference plane.

[0078] In some embodiments, using the characteristics of the MP generalized inverse, solving the minimum least squares solution from each discrete point to the cementoenamel junction reference plane includes:

[0079] Constructing a reference plane equation in functional form and substituting the coordinates of each discrete point into it;

[0080] Obtaining the vector form of the reference plane equation Ax=b, where A is a matrix and b is a constant vector;

[0081] Determine the MP generalized inverse A of matrix A + ;

[0082] Based on A + The properties of are used to obtain the minimum least squares solution of x, thereby obtaining the cementoenamel junction reference plane.

[0083] In some embodiments, determining the tooth long axis based on the tooth center coordinates and the cementoenamel junction reference plane in step S140 includes:

[0084] Determine a perpendicular line passing through the tooth center coordinate and perpendicular to the cementoenamel junction reference plane, and the perpendicular line is the straight line where the long axis of the tooth is located.

[0085] In a specific embodiment, a method for determining the long axis of a tooth based on three-dimensional digitization includes the following steps:

[0086] S1. Use cone beam CT machine to obtain three-dimensional volume data of oral patients;

[0087] S2, performing three-dimensional reconstruction on cone-beam CT data;

[0088] S3, select and segment the enamel;

[0089] S4, performing binarization processing on the segmented image to construct segmented enamel three-dimensional spatial point cloud data;

[0090] S5. Automatically or manually select n (n ≥ 3) evenly distributed discrete points at the cementoenamel junction, i.e., point P ({P∈R 3}), and record its coordinate values;

[0091] S6. Since the coordinates of the spatial point P are known, the tooth center can be directly calculated using formula (1) The coordinates of

[0092]

[0093] S7, take each point P in space i The 2-norm to plane α is minimized, and the reference plane can be uniquely determined.

[0094] Let the reference plane α be expressed as:

[0095] α:ax+by+cz+d=0 (2)

[0096] Where a, b, c, and d are unknown parameters, and c≠0.

[0097] Rewriting it into a function form, we get:

[0098]

[0099] make Then we have:

[0100] z=jx+ky+l (4)

[0101] It can be seen that the construction process of α has been transformed into the process of determining the unknown parameters j, k and l.

[0102] S8, each point P in space i Substituting the coordinate values ​​into formula (4), we have:

[0103]

[0104] Because P i Since they are not coplanar, the equations in (5) are obviously not valid.

[0105] Then rewrite (5) into vector form and find the plane expression with the minimum 2-norm, that is:

[0106] Ax=b (6)

[0107] The coefficient matrices A and b are:

[0108]

[0109] S9, using the special properties of the MP generalized inverse (Moore-Penrose Generalized Inverse), the unique determination of the P at each point in space i The reference plane α with the minimum 2-norm, the plane equation at this time is:

[0110] j m x+k m y-z+l m =0 (8)

[0111] S10, after the reference plane α is determined, pass through the tooth center Draw a perpendicular line L to α to get the long axis of the tooth. Figure 2 and Figure 3 shown.

[0112] Since the perpendicular line L⊥α, the two direction vectors are parallel, thus the parametric equation of the line is obtained:

[0113]

[0114] Where t is a parameter.

[0115] The special properties of the above MP generalized inverse are:

[0116] For any m×n matrix A, there exists a matrix X that satisfies the following conditions:

[0117] AXA=A

[0118] XAX=X

[0119] (AX) H =AX

[0120] (XA) H =XA

[0121] Among them, A H Represents the conjugate transpose of A. The matrix X that satisfies all the above four conditions is called the MP generalized inverse of matrix A, denoted by A + .

[0122] The only approximate solution is:

[0123] x m =A + b

[0124] Among them, x m =(j m , k m , l m ) T This is the minimum least squares solution to the equation.

[0125] In summary, compared with the existing technology, the above-mentioned three-dimensional digital tooth long axis determination method can determine the unique long axis of each tooth through mathematical methods based on cone-beam CT images, with high accuracy and reliability. It provides highly repeatable three-dimensional digital measurement reference planes and reference axes (i.e., three-dimensional coordinate systems) for manual measurement and AI automated recognition measurement of cone-beam CT clinical indicators, laying a solid theoretical foundation for clinical research in the field of AI automation in stomatology.

[0126] According to another aspect of the present invention, see Figure 4 As shown, a device for determining the long axis of a tooth is provided, and the device 400 includes:

[0127] The data acquisition module 410 acquires oral cone-beam CT data and segments the tooth enamel;

[0128] A coordinate determination module 420 is adapted to select a plurality of discrete points of the tooth enamel at the cementoenamel junction of the tooth enamel and obtain the coordinates of each of the discrete points;

[0129] A plane determination module 430 is adapted to determine the coordinates of the tooth center and the cementoenamel junction reference plane according to the coordinates of each discrete point;

[0130] The tooth long axis determination module 440 is adapted to determine the tooth long axis based on the tooth center coordinates and the cementoenamel junction reference plane.

[0131] The method for determining the long axis of the tooth provided in the above embodiment can determine the angle and distance information of the tooth relative to the alveolar bone through the long axis of the tooth, provide a reference for oral surgery such as implant restoration, and improve the accuracy of oral surgery; on the other hand, it also provides highly repeatable three-dimensional digital measurement reference planes and reference axes for manual measurement and AI automated recognition measurement of cone beam CT clinical indicators, thereby determining the three-dimensional coordinate system of the tooth, laying a solid theoretical foundation for clinical research in the field of AI automation in oral medicine.

[0132] In some embodiments, the data acquisition module 410 is specifically adapted to:

[0133] Acquiring oral three-dimensional volume data, wherein the oral three-dimensional volume data is obtained from a cone-beam CT machine;

[0134] Performing three-dimensional reconstruction on the oral three-dimensional volume data to obtain cone-beam CT data;

[0135] The tooth enamel is segmented from the cone-beam CT data, the tooth enamel is binarized, and three-dimensional point cloud data of the segmented tooth enamel is constructed.

[0136] In some embodiments, the coordinate determination module 420 is adapted to:

[0137] At the cementoenamel junction, multiple evenly distributed discrete points are selected, and the three-dimensional coordinate value of each discrete point is obtained and recorded.

[0138] In some embodiments, the plane determination module 430 is adapted to:

[0139] The average value of the three-dimensional coordinates of each of the discrete points is calculated, and the coordinates of the tooth center are determined based on the average value.

[0140] In some embodiments, determining the cementoenamel junction reference plane according to the coordinates of each discrete point in step S130 includes:

[0141] The characteristics of the MP generalized inverse are used to solve the minimum least square solution from each discrete point to the cementoenamel junction reference plane, thereby determining the cementoenamel junction reference plane.

[0142] In some embodiments, using the characteristics of the MP generalized inverse, solving the minimum least squares solution from each discrete point to the cementoenamel junction reference plane includes:

[0143] Constructing a reference plane equation in functional form and substituting the coordinates of each discrete point into it;

[0144] Obtaining the vector form of the reference plane equation Ax=b;

[0145] Determine the MP generalized inverse A of matrix A + ;

[0146] Based on A + The properties of are used to obtain the minimum least squares solution of x, thereby obtaining the enamel-cementum junction reference plane.

[0147] In some embodiments, the tooth long axis determination module 440 is adapted to:

[0148] Determine a perpendicular line passing through the tooth center coordinate and perpendicular to the cementoenamel junction reference plane, and the perpendicular line is the straight line where the long axis of the tooth is located.

[0149] It should be noted that the specific implementation of the above-mentioned device embodiments can refer to the specific implementation of the above-mentioned corresponding method embodiments, which will not be repeated here.

[0150] It should be noted that:

[0151] The algorithm and display provided herein are not inherently related to any particular computer, virtual device or other equipment. Various general-purpose devices can also be used together with the teachings based on this. According to the above description, it is obvious that the structure required for constructing this type of device. In addition, the present invention is not directed to any specific programming language. It should be understood that various programming languages ​​can be utilized to implement the content of the present invention described herein, and the above description of specific languages ​​is for the purpose of disclosing the best mode of the present invention.

[0152] In the description provided herein, numerous specific details are described. However, it is understood that embodiments of the present invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0153] Similarly, it should be understood that in order to streamline the invention and aid understanding of one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim.

[0154] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and in addition may be divided into multiple submodules or subunits or subcomponents. All features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed herein may be combined in any combination, except that at least some of such features and / or processes or units are mutually exclusive. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0155] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features and not other features included in other embodiments, the combination of features from different embodiments is intended to be within the scope of the invention and to form different embodiments.

[0156] The various component embodiments of the present invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art will appreciate that in practice, a microprocessor or digital signal processor (DSP) may be used to implement some or all of the functions of some or all of the components of the tooth long axis determination device according to an embodiment of the present invention. The present invention may also be implemented as an apparatus or device program (e.g., a computer program and computer program product) for executing part or all of the methods described herein. Such a program implementing the present invention may be stored on a computer-readable medium, or may be in the form of one or more signals. Such a signal may be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0157] An embodiment of the present invention provides a non-volatile computer storage medium storing at least one executable instruction. The computer executable instruction can execute the tooth long axis determination method in any of the above method embodiments.

[0158] Figure 5The schematic diagram of the structure of an electronic device embodiment of the present invention is shown. The specific embodiment of the present invention does not limit the specific implementation of the electronic device.

[0159] like Figure 5 As shown, the electronic device may include: a processor (processor) 502 , a communication interface (Communications Interface) 504 , a memory (memory) 506 , and a communication bus 508 .

[0160] Processor 502, communication interface 504, and memory 506 communicate with each other via communication bus 508. Communication interface 504 is used to communicate with other devices, such as client devices or other server network elements. Processor 502 is used to execute program 510, which may specifically perform the steps described in the embodiment of the tooth long axis determination method for an electronic device.

[0161] Specifically, the program 510 may include program codes, which include computer operation instructions.

[0162] Processor 502 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention. The one or more processors included in the onboard image processing board may be of the same type, such as one or more CPUs, or may be of different types, such as one or more CPUs and one or more ASICs.

[0163] The memory 506 is used to store the program 510. The memory 506 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0164] The program 510 can be specifically used to enable the processor 502 to perform operations corresponding to the above-mentioned embodiment of the method for determining the long axis of a tooth.

[0165] It should be noted that the above embodiments illustrate rather than limit the present application, and that a person skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbols placed between brackets should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present application may be implemented by means of hardware comprising several different elements and by means of appropriately programmed computers. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

Claims

1. A method for determining a tooth's long axis, the method comprising: Acquire oral cone-beam CT data and segment the enamel; At the cementoenamel junction of the tooth enamel, selecting a plurality of discrete points of the tooth enamel and obtaining the coordinates of each of the discrete points; Determine the tooth center coordinates and the cementoenamel junction reference plane according to the coordinates of each discrete point; The long axis of the tooth is determined based on the tooth center coordinates and the cementoenamel junction reference plane.

2. The method according to claim 1, characterized in that Acquiring cone-beam CT data and segmenting tooth enamel involves: Acquiring oral three-dimensional volume data, wherein the oral three-dimensional volume data is obtained from a cone-beam CT machine; Performing three-dimensional reconstruction on the oral three-dimensional volume data to obtain cone-beam CT data; The tooth enamel is segmented from the cone-beam CT data, the tooth enamel is binarized, and three-dimensional point cloud data of the segmented tooth enamel is constructed.

3. The method according to claim 1, characterized in that Selecting multiple discrete points of tooth enamel and obtaining coordinates of each of the discrete points includes: At the cementoenamel junction, multiple evenly distributed discrete points are selected, and the three-dimensional coordinate value of each discrete point is obtained and recorded.

4. The method according to any one of claims 1 to 3, characterized in that Determining the coordinates of the tooth center according to the coordinates of each discrete point includes: The average value of the three-dimensional coordinates of each of the discrete points is calculated, and the coordinates of the tooth center are determined based on the average value.

5. The method according to any one of claims 1 to 3, characterized in that Determining the cementoenamel junction reference plane according to the coordinates of each discrete point includes: The characteristics of the MP generalized inverse are used to solve the minimum least square solution from each discrete point to the cementoenamel junction reference plane, thereby determining the cementoenamel junction reference plane.

6. The method according to claim 5, characterized in that Using the characteristics of the MP generalized inverse, solving the minimum least squares solution from each discrete point to the cementoenamel junction reference plane includes: Constructing a reference plane equation in functional form and substituting the coordinates of each discrete point into it; Obtaining the vector form of the reference plane equation Ax=b; Determine the MP generalized inverse A of matrix A + ; Based on A + The properties of are used to obtain the minimum least squares solution of x, thereby obtaining the enamel-cementum junction reference plane.

7. The method according to any one of claims 1 to 3, characterized in that Determining the tooth long axis based on the tooth center coordinates and the cementoenamel junction reference plane includes: Determine a perpendicular line passing through the tooth center coordinate and perpendicular to the cementoenamel junction reference plane, and the perpendicular line is the straight line where the long axis of the tooth is located.

8. A device for determining a tooth's long axis, comprising: Data acquisition module, which acquires oral cone-beam CT data and segments tooth enamel; a coordinate determination module adapted to select a plurality of discrete points of the tooth enamel at the cementoenamel junction of the tooth enamel and obtain the coordinates of each of the discrete points; a plane determination module adapted to determine the coordinates of the tooth center and the cementoenamel junction reference plane according to the coordinates of each of the discrete points; The tooth long axis determination module is adapted to determine the tooth long axis based on the tooth center coordinates and the cementoenamel junction reference plane.

9. An electronic device comprising: processor; and a memory arranged to store computer-executable instructions, which, when executed, cause the processor to perform the tooth long axis determination method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores one or more programs, and when the one or more programs are executed by a processor, the method for determining a tooth long axis according to any one of claims 1 to 7 is implemented.

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