Method and device for determining target position of mandibular angle osteotomy surface and storage medium

Abstract

The invention relates to a method and device for determining the target position of a mandible angle osteotomy surface and a storage medium, and the method comprises the steps: obtaining a mandible model, carrying out the division of a hierarchical bounding box, determining the center and direction of the mandible model, and obtaining the pose information of the mandible model in a space; according to the pose information of the mandible model, determining the position of the mandible ramus so as to construct an occlusal surface; based on the occlusal surface, determining an intersection point of the occlusal surface and the mandibular external oblique line and an intersection point of the occlusal surface and the mandibular ramus; further determining a projection point of the second molar point on the lower edge of the mandible, a posterior lower point of a mandibular angle, the most vertex of a condylar process and a chin protrusion point; and iteratively obtaining an optimal osteotomy surface according to each determined feature point of the mandible model, and calculating corresponding key anatomical parameters. Compared with the prior art, the method is beneficial to the automatic generation and planning of the operation direction, saves the time of a doctor, and is excellent in algorithm robustness and generalization ability.

Description

Technical Field

[0001] The present invention relates to the technical field of data processing, and in particular to a method, a device and a storage medium for determining a target position of a mandibular angle osteotomy surface. Background Art

[0002] With the development of personalized plastic surgery technology, mandibular angle osteotomy has gradually become popular among patients with mandibular angle hypertrophy. The goal of this surgery is to remove the more prominent part of the mandibular angle in a limited manner according to the patient's personal facial conditions to achieve a smooth curved facial contour.

[0003] This operation is difficult to perform and has high surgical risks. This is mainly because there are many important nerves and blood vessels around the mandible, including the facial artery, maxillary artery, alveolar artery, mandibular nerve, inferior alveolar nerve (IAN), mental nerve, facial nerve, etc. Improper operation will cause complications such as neurovascular injury, chewing dysfunction, and mandibular fracture. Traditional manual operation, surgical guides, and surgical navigation are commonly used methods for mandibular angle osteotomy in clinical practice. In recent years, the application of technologies such as augmented reality and surgical robots in maxillofacial surgery has become increasingly popular in academia and clinic.

[0004] Regardless of which of the above surgical methods is used, the formulation of a preoperative surgical planning plan and the measurement of the patient's personalized anatomical parameters are prerequisites for achieving accurate and quantitative mandibular angle osteotomy. The process first uses the patient's preoperative CT image data to perform image segmentation and three-dimensional reconstruction of the mandible, and then the surgeon sets the osteotomy plane based on previous clinical experience. Due to the high degree of patient personalization and the large differences in doctors' clinical experience, the design of the surgical planning plan requires repeated adjustments and evaluations, resulting in low efficiency in preoperative planning. According to relevant reports, the average surgical planning time for doctors to complete a mandibular angle osteotomy is more than 40 minutes. At the same time, because different doctors rely heavily on experience in the preoperative planning process, it brings great difficulties to the standardization and promotion of surgery.

[0005] In summary, among the existing solutions, manual or semi-manual methods require doctors to have sufficient experience, which increases the learning cost; and steps such as identifying landmarks are time-consuming and labor-intensive, which complicates the process and prolongs the preoperative preparation time; and there are differences in the anatomical feature points selected by different doctors, and the osteotomy plans finally generated are also inconsistent, and standardized plan planning cannot be achieved.

[0006] The method of using AI for automatic planning requires a large number of representative data sets to train the model, which requires doctors to spend a lot of time collecting and annotating data. In addition, the robustness and generalization ability of such methods also need to be further improved. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method, device and storage medium for determining the target position of the mandibular angle osteotomy surface, improve the robustness and generalization ability, and facilitate the automatic generation and planning of surgical direction.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] A method for determining a target position of a mandibular angle osteotomy surface comprises the following steps:

[0010] Obtain the mandibular model, divide it into hierarchical bounding boxes, determine the center and direction of the mandibular model, and obtain the position information of the mandibular model in space;

[0011] According to the posture information of the mandibular model, the mandibular bone is cut at fixed intervals starting from the most anterior position of the mandibular bone, and the position of the mandibular ascending ramus is determined according to the change of the highest point of the contour obtained by cutting, so as to construct the occlusal surface;

[0012] The mandibular model is cut based on the occlusal plane to obtain the two largest connected domains, thereby determining the intersection of the occlusal plane with the mandibular external oblique line and the intersection of the occlusal plane with the mandibular ascending ramus;

[0013] According to the cut plane, the lowest point of the cross-sectional contour in the plane forward of the mandibular ramus is taken as the projection point of the second molar point on the lower edge of the mandible;

[0014] According to the distribution of the mandibular inferior surface and the posterior surface of the mandibular ramus in the mandibular model, the posterior inferior point of the mandibular angle is determined;

[0015] The highest point of the entire mandibular model was taken as the apex of the condyle, and the most anterior point of the entire mandibular model was taken as the chin bulge.

[0016] According to the determined characteristic points of the mandibular model, the optimal osteotomy surface is iteratively obtained and the corresponding key anatomical parameters are calculated.

[0017] Furthermore, the process of determining the center and direction of the mandibular model is specifically as follows:

[0018] Performing two-level bounding box division on the mandibular model, dividing the mandibular model into four parts: left mandibular ramus, right mandibular ramus, left half mandibular body and right half mandibular body;

[0019] According to the bounding boxes of the left and right half mandibular bodies, the normal vectors of the long axes are cross-multiplied to obtain the downward direction of the mandibular model; the normal vectors of the long axes are added to obtain the forward direction of the mandibular model; the downward and forward directions of the mandibular model are cross-multiplied to obtain the left direction of the mandibular model.

[0020] Furthermore, the process of constructing the occlusal surface is specifically as follows: according to the determined position of the mandibular ascending ramus, the two uppermost points in the cutting plane at the first distance in front of the position of the mandibular ascending ramus are used as the upper edge points of the left and right first molars, and the uppermost point of the incisor is taken in combination to construct the occlusal surface.

[0021] Furthermore, in the two largest connected domains obtained based on the occlusal plane cutting, the nearest point in the forward direction of the mandibular model is searched as the intersection point of the occlusal plane and the mandibular external oblique line; the farthest point in the forward direction of the mandibular model is searched as the intersection point of the occlusal plane and the mandibular ascending ramus.

[0022] Furthermore, the process of determining the projection point of the second molar point on the lower edge of the mandible includes:

[0023] Select a plane at the second distance forward from the position of the mandibular ramus, and select the lowest point in the cross-sectional profile of the plane as the projection point of the second molar point on the lower edge of the mandible.

[0024] Furthermore, the process of determining the posterior lower point of the mandibular angle comprises the following steps:

[0025] The mandibular inferior surface and the posterior surface of the mandibular ramus are determined in the mandibular model, and the intersection line between the mandibular inferior surface and the posterior surface of the mandibular ramus is selected as the auxiliary line. The point closest to the auxiliary line is selected in the mandibular model as the posterior-inferior point of the mandibular angle.

[0026] Furthermore, the process of determining the lower edge surface of the mandible is specifically as follows: iteratively calculating the points in the mandibular model where the angle between the normal vector and the gravity direction of the mandibular model is less than a first threshold, forming a directed bounding box, and using the gravity direction of the directed bounding box as the new gravity direction, reconstructing the directed bounding box until the gravity direction or the directed bounding box no longer changes, and constructing the lower edge surface of the mandible based on the points of the directed bounding box at this time.

[0027] Furthermore, the process of obtaining the optimal osteotomy surface includes:

[0028] The intersection of the occlusal surface and the mandibular external oblique line, as well as the projection point of the second molar point on the lower edge of the mandible, constitute the osteotomy auxiliary straight line and the initial osteotomy surface. With the osteotomy auxiliary straight line as the axis, the normal vector of the osteotomy surface is rotated until the normal vector of the osteotomy surface corresponding to the minimum contour area intercepted by the osteotomy surface in the mandibular model is found; the distance between the osteotomy surface and the neural canal in the mandibular model at this time is calculated. If it is not greater than the set distance threshold, the origin of the current osteotomy surface is moved in the opposite direction of the normal vector until the distance to the neural canal is equal to the distance threshold; if it is greater than the preset distance threshold, the osteotomy surface at this time is used as the optimal osteotomy surface.

[0029] The present invention also provides a device for determining the target position of the mandibular angle osteotomy surface, comprising a memory and a processor, wherein the memory stores a computer program, and the processor calls the computer program to execute the steps of the above method.

[0030] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and the computer program is executed by a processor to perform the above method.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The method provided by the present invention realizes fully automatic detection of mandibular anatomical feature points, and successively determines the occlusal surface of the mandibular model, the intersection of the occlusal surface and the mandibular external oblique line, the projection point of the second molar point on the lower edge of the mandible and other features, and realizes step-by-step analysis and calculation. The algorithm has excellent robustness and generalization ability. In addition, a mandibular osteotomy plane optimization method is established to obtain key anatomical measurement parameters, which is conducive to the automatic generation and planning of surgical directions and saves doctors' time.

[0033] (2) The algorithm of the present invention has less error than manual determination by doctors and the results are reliable.

[0034] (3) The present invention proposes a set of standard procedures for mandibular osteotomy plans, which is conducive to coordinating the habits of different doctors. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic flow chart of a method for determining a target position of a mandibular angle osteotomy surface provided in an embodiment of the present invention;

[0036] Figure 2 A simplified schematic diagram of a method for determining a target position of a mandibular angle osteotomy surface provided in an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of a process for determining the center and direction of a mandibular model provided in an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of a process of determining the occlusal surface provided in an embodiment of the present invention;

[0039] Figure 5 A schematic diagram of a process for determining a trailing edge surface provided in an embodiment of the present invention;

[0040] Figure 6 The figure is a schematic diagram of a flow chart for determining an osteotomy surface provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0044] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0045] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0046] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0047] Example 1

[0048] like Figure 1 and Figure 2 As shown, this embodiment provides a method for determining the target position of the mandibular angle osteotomy surface, comprising the following steps:

[0049] S1: Obtain the mandibular model, divide it into hierarchical bounding boxes, determine the center and direction of the mandibular model, and obtain the position information of the mandibular model in space;

[0050] Optionally, the process of determining the center and orientation of the mandibular model is as follows:

[0051] The mandibular model was divided into four parts: the left mandibular ramus, the right mandibular ramus, the left half mandibular body and the right half mandibular body by two-level bounding box division.

[0052] According to the bounding boxes of the left and right half mandibular bodies, the normal vectors of the long axes are cross-multiplied to obtain the downward direction of the mandibular model; the normal vectors of the long axes are added to obtain the forward direction of the mandibular model; the downward and forward directions of the mandibular model are cross-multiplied to obtain the left direction of the mandibular model.

[0053] In this embodiment, specifically: Figure 3 As shown, the directed bounding box OBB of the entire mandible is calculated MB And get its center O MB . The hierarchical bounding box (HBB) can divide the space into a series of bounding boxes and organize them in a tree structure; here we set the basis for dividing the tree structure to be to find a plane so that the volumes on both sides of the face are equal. If we calculate the hierarchical bounding box for the mandible, the morphology of the mandible is rather special, and its overall morphological structure is close to "a semicircle plus two upward 'branches'". Due to the symmetry of the mandibular structure, the initial mean dividing plane will be close to the midline of the face; if we continue to calculate the second-order hierarchical bounding box, due to the anatomical characteristics of the mandible (the mandibular ramus is close to the mandibular body in width, and the mandibular body is nearly twice the length of the mandibular ramus), the mean dividing plane will be roughly located at the intersection of the mandibular ascending ramus and the mandibular body. Therefore, by calculating the second-order hierarchical bounding box for the mandible, the mandible can be divided into four parts: the left and right mandibular ascending ramus and the left and right half mandibular bodies, such as Figure 1 After obtaining the bounding boxes of the left and right hemimandibular bodies, the downward direction of the mandible can be obtained by cross-producting the normal vectors of the long axes of the three axes: The forward direction can be found by adding the two major axis normal vectors: The final left direction can be obtained by cross-producting the downward direction and the forward direction: At this point, the position information of the mandible in space has been determined.

[0054] S2: Based on the posture information of the mandibular model, the mandibular bone is cut at fixed intervals starting from the most anterior position of the mandibular bone, and the position of the mandibular ramus is determined according to the change of the highest point of the cut contour, thereby constructing the occlusal surface;

[0055] The process of constructing the occlusal surface can be as follows: based on the determined position of the mandibular ramus, the two uppermost points in the cutting plane at the first distance in front of the position of the mandibular ramus are used as the upper edge points of the left and right first molars, and the uppermost point of the incisor is combined to construct the occlusal surface.

[0056] The construction process of the occlusal surface can also be: Two sections were made at a certain distance in front of the mandibular ramus, and the mandible was cut separately. The middle part of the two sections was taken, the directed bounding box was calculated, and the upper surface of the bounding box was iterated so that the plane was exactly tangent to the incisor.

[0057] In this embodiment, Figure 4 As shown in the figure, after obtaining the position information of the mandible in space, from the most front part of the mandible (i.e. The mandible is cut with a series of planes at fixed intervals starting from the most anterior position in the direction of the mandible. The normal vectors of these sections are The position of the mandibular ramus is determined by the change of the highest point of the contour obtained by cutting. After the position of the mandibular ramus is determined, the normal vector When making a cross section, the two uppermost points of the cross section are the upper edge points of the left and right first molars; another uppermost point of the incisor is taken; the plane formed by the three points is the occlusal surface (OP).

[0058] S3: Cut the mandibular model based on the occlusal plane to obtain the two largest connected domains, thereby determining the intersection of the occlusal plane with the mandibular external oblique line and the intersection of the occlusal plane with the mandibular ascending ramus;

[0059] Specifically, in the two largest connected domains obtained based on the occlusal plane cutting, the nearest point in the forward direction of the mandibular model is searched as the intersection point of the occlusal plane and the mandibular external oblique line; the farthest point in the forward direction of the mandibular model is searched as the intersection point of the occlusal plane and the mandibular ascending ramus.

[0060] In this embodiment, specifically, after determining the position of the occlusal surface, the mandibular model is cut with the occlusal surface, and two largest connected domains are obtained from the cut contour to filter the cut area of ​​the occlusal surface and the tooth part. The two contour boundaries are recorded as C Left and C Right . Get C Left and C Right The distance inside the contour point The nearest point can be obtained Left and O Right Similarly, by obtaining the farthest point, we can get and A 2Right .

[0061] S4: According to the cut plane, the lowest point of the cross-sectional contour in the plane forward of the mandibular ramus is taken as the projection point of the second molar point on the lower edge of the mandible;

[0062] The process of determining the projection point of the second molar point on the lower edge of the mandible specifically includes:

[0063] Select a plane at the second distance forward from the position of the mandibular ramus, and select the lowest point in the cross-sectional profile of the plane as the projection point of the second molar point on the lower edge of the mandible.

[0064] In this embodiment, the position of the mandibular ramus obtained in step S2 is moved forward a certain distance. Make a cross section with the normal vector as the center point, and take the lowest point of the cross section as E. Left and E Right .

[0065] S5: According to the distribution of the mandibular inferior surface and the posterior surface of the mandibular ramus in the mandibular model, determine the posterior inferior point of the mandibular angle;

[0066] Optionally, the process of determining the posterior inferior point of the mandibular angle includes the following steps:

[0067] The mandibular inferior surface and the posterior surface of the mandibular ramus are determined in the mandibular model, and the intersection line between the mandibular inferior surface and the posterior surface of the mandibular ramus is selected as the auxiliary line. The point closest to the auxiliary line is selected in the mandibular model as the posterior-inferior point of the mandibular angle.

[0068] The specific process of determining the lower edge surface of the mandible is: iteratively calculate the points in the mandibular model where the angle between the normal vector and the gravity direction of the mandibular model is less than the first threshold, form a directed bounding box, and use the gravity direction of the directed bounding box as the new gravity direction, and reconstruct the directed bounding box until the gravity direction or the directed bounding box no longer changes. The lower edge surface of the mandible is constructed based on the points of the directed bounding box at this time.

[0069] The process of confirming the posterior edge of the mandibular ramus is similar.

[0070] In this embodiment, in order to determine the position of the lower posterior point Go of the mandibular angle, an auxiliary line l needs to be constructed. MA , l MA S is the lower edge of the mandible down and the posterior edge of the mandibular ramus S back and Go is the intersection line from l to l in the preoperatively reconstructed three-dimensional model of the mandible. MA The nearest point. Go = argminD is (m i ,l MA ).in, represents the distance function, m i ∈M. At this point, the lower and posterior points Go of the left and right mandibular angles can be obtained.Left and Go Right . Lower edge surface S down The method is roughly as follows: Figure 5 As shown, the normal vector of the mandible is iterated and the gravity direction The angle between them is less than the threshold T NV The directed bounding box OBB formed by the points M , and OBB M The gravity direction is taken as the new gravity direction until the gravity direction or OBB M No longer changes. Trailing edge surface S back The same principle applies to the method of seeking the truth.

[0071] S6: The highest point in the entire mandibular model was taken as the apex of the condyle (Co), and the most anterior point in the entire mandibular model was taken as the chin bulge (Me);

[0072] S7: iteratively obtain the optimal osteotomy surface according to each characteristic point of the determined mandibular model;

[0073] The process of obtaining the best osteotomy surface includes:

[0074] The intersection of the occlusal surface and the mandibular external oblique line, as well as the projection point of the second molar point on the lower edge of the mandible, constitute the osteotomy auxiliary straight line and the initial osteotomy surface. With the osteotomy auxiliary straight line as the axis, the normal vector of the osteotomy surface is rotated until the normal vector of the osteotomy surface corresponding to the minimum contour area intercepted by the osteotomy surface in the mandibular model is found; the distance between the osteotomy surface and the neural canal in the mandibular model at this time is calculated. If it is not greater than the set distance threshold, the origin of the current osteotomy surface is moved in the opposite direction of the normal vector until the distance to the neural canal is equal to the distance threshold; if it is greater than the preset distance threshold, the osteotomy surface at this time is used as the optimal osteotomy surface.

[0075] The specific process of this embodiment is as follows: Figure 6 As shown, the osteotomy surface must pass through points A2 and E. A straight line l is formed through points A2 and E. A2E , with l A2E The normal vector of the osteotomy surface is rotated by the axis, and the normal vector that can minimize the area of ​​the contour obtained by the osteotomy surface cutting the mandible is the normal vector of the final osteotomy surface. The distance D from the osteotomy surface to the neural canal is calculated. If D < 5mm, the origin of the osteotomy surface is moved in the opposite direction of the normal vector until D = 5mm; if D > 5mm, no operation is performed.

[0076] S8: Calculate the corresponding key anatomical parameters.

[0077] This embodiment specifically calculates the distances of Co-Go, Co-A2, Go-Go, and A2-A2, and the angles of Co-Go-Me and Co-A2-Me.

[0078] This embodiment also provides a device for determining the target position of the mandibular angle osteotomy surface, including a memory and a processor, wherein the memory stores a computer program, and the processor calls the computer program to execute the steps of the above-mentioned method for determining the target position of the mandibular angle osteotomy surface.

[0079] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. The computer program is executed by a processor to implement the above-mentioned method for determining the target position of the mandibular angle osteotomy surface.

[0080] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for determining a target position of a mandibular angle osteotomy surface, characterized in that: The following steps are involved: Obtain the mandibular model, divide it into hierarchical bounding boxes, determine the center and direction of the mandibular model, and obtain the position information of the mandibular model in space; According to the posture information of the mandibular model, the mandibular bone is cut at fixed intervals starting from the most anterior position of the mandibular bone, and the position of the mandibular ascending ramus is determined according to the change of the highest point of the contour obtained by cutting, so as to construct the occlusal surface; The mandibular model is cut based on the occlusal plane to obtain the two largest connected domains, thereby determining the intersection of the occlusal plane with the mandibular external oblique line and the intersection of the occlusal plane with the mandibular ascending ramus; According to the cut plane, the lowest point of the cross-sectional contour in the plane forward of the mandibular ramus is taken as the projection point of the second molar point on the lower edge of the mandible; According to the distribution of the mandibular inferior surface and the posterior surface of the mandibular ramus in the mandibular model, the posterior inferior point of the mandibular angle is determined; The highest point of the entire mandibular model was taken as the apex of the condyle, and the most anterior point of the entire mandibular model was taken as the chin bulge. According to the determined characteristic points of the mandibular model, the optimal osteotomy surface is iteratively obtained and the corresponding key anatomical parameters are calculated.

2. A method for determining a target position of a mandibular angle osteotomy surface according to claim 1, characterized in that: The process of determining the center and direction of the mandibular model is specifically as follows: Performing two-level bounding box division on the mandibular model, dividing the mandibular model into four parts: left mandibular ramus, right mandibular ramus, left half mandibular body and right half mandibular body; According to the bounding boxes of the left and right half mandibular bodies, the normal vectors of the long axes are cross-multiplied to obtain the downward direction of the mandibular model; the normal vectors of the long axes are added to obtain the forward direction of the mandibular model; the downward and forward directions of the mandibular model are cross-multiplied to obtain the left direction of the mandibular model.

3. A method for determining a target position of a mandibular angle osteotomy surface according to claim 1, characterized in that: The specific process of constructing the occlusal surface is as follows: according to the determined position of the mandibular ascending ramus, the two uppermost points in the cutting plane at the first distance in front of the position of the mandibular ascending ramus are used as the upper edge points of the left and right first molars, and the uppermost point of the incisor is combined to construct the occlusal surface.

4. A method for determining a target position of a mandibular angle osteotomy surface according to claim 1, characterized in that: In the two largest connected domains obtained based on the occlusal plane cutting, searching for the nearest point in the forward direction of the mandibular model as the intersection point of the occlusal plane and the mandibular external oblique line; The farthest point in the forward direction of the mandibular model is searched as the intersection point of the occlusal surface and the mandibular ascending ramus.

5. The method for determining the target position of the mandibular angle osteotomy surface according to claim 1, characterized in that: The process of determining the projection point of the second molar point on the lower edge of the mandible includes: Select a plane at the second distance forward from the position of the mandibular ramus, and select the lowest point in the cross-sectional profile of the plane as the projection point of the second molar point on the lower edge of the mandible.

6. A method for determining a target position of a mandibular angle osteotomy surface according to claim 1, characterized in that: The process of determining the posterior lower point of the mandibular angle comprises the following steps: The mandibular inferior surface and the posterior surface of the mandibular ramus are determined in the mandibular model, and the intersection line between the mandibular inferior surface and the posterior surface of the mandibular ramus is selected as the auxiliary line. The point closest to the auxiliary line is selected in the mandibular model as the posterior-inferior point of the mandibular angle.

7. A method for determining a target position of a mandibular angle osteotomy surface according to claim 6, characterized in that: The process of determining the lower edge surface of the mandible is specifically as follows: iteratively calculate the points in the mandibular model where the angle between the normal vector and the gravity direction of the mandibular model is less than a first threshold, forming a directed bounding box, and using the gravity direction of the directed bounding box as the new gravity direction, reconstructing the directed bounding box until the gravity direction or the directed bounding box no longer changes, and constructing the lower edge surface of the mandible based on the points of the directed bounding box at this time.

8. The method for determining the target position of the mandibular angle osteotomy surface according to claim 1, characterized in that: The process of obtaining the optimal osteotomy surface includes: The intersection of the occlusal surface and the mandibular external oblique line, as well as the projection point of the second molar point on the lower edge of the mandible, constitute the osteotomy auxiliary straight line and the initial osteotomy surface. With the osteotomy auxiliary straight line as the axis, the normal vector of the osteotomy surface is rotated until the normal vector of the osteotomy surface corresponding to the minimum contour area intercepted by the osteotomy surface in the mandibular model is found; the distance between the osteotomy surface and the neural canal in the mandibular model at this time is calculated. If it is not greater than the set distance threshold, the origin of the current osteotomy surface is moved in the opposite direction of the normal vector until the distance to the neural canal is equal to the distance threshold; if it is greater than the preset distance threshold, the osteotomy surface at this time is used as the optimal osteotomy surface.

9. A device for determining the target position of the mandibular angle osteotomy surface, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and the processor calls the computer program to execute the steps of any one of the methods according to claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is used by a processor to execute the method according to any one of claims 1 to 8.

Images