Full-mouth automatic tooth arrangement method and system based on occlusal plane feature points

Abstract

The invention relates to the technical field of oral medicine, in particular to a full-mouth automatic tooth arrangement method and system based on occlusal plane feature points. Further obtaining the coordinates of the center of mass of each tooth, the first limiting distance of each tooth, the feature points of the # imgabs0 # surface of each tooth and the set allowable movement direction; matching the upper and lower jaw teeth; aligning the z-axis of the coordinates of the centroid point of each tooth pair, and performing coarse registration on the tooth pair according to the first limiting distance and the allowed moving direction; according to the point cloud data of the two teeth in the tooth pair, finishing fine registration of the upper and lower jaw teeth by constructing a target function; and according to the alveolar ridge crest line and the minimum distance between two adjacent teeth in the same jaw, constructing an objective function to optimize tooth arrangement. According to the invention, the teeth are optimally arranged while the perfect meshing of the teeth is preferably met, so that the attractive and tidy degree of the tooth arrangement result is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oral medicine, and in particular to a full-mouth automatic teeth arrangement method and system based on occlusal plane feature points. Background Art

[0002] In the process of making full dentures, obtaining artificial dentition that meets the patient's oral characteristics is one of the key steps to a successful restoration. Good artificial dentition can effectively restore the patient's chewing function, reshape the facial shape, and enhance the patient's confidence.

[0003] At present, the following three methods are mainly used for full-mouth automatic tooth arrangement:

[0004] Method 1 is specifically as follows: 1) establish a three-dimensional database of standard teeth features; 2) extract patient oral feature information; 3) arrange teeth. This tooth arrangement method for making full dentures establishes a mutual constraint relationship between the oral cavity and artificial teeth, thereby achieving automatic tooth arrangement and obtaining dentition that meets the oral characteristics of different patients. The arranged dentition can be appropriately adjusted according to the needs of the patient to meet the patient's gender, age, etc., effectively meeting the clinical needs of full dentures.

[0005] Method 2 is specifically as follows: virtually complete the original dentition image to obtain a complete dentition image; perform tooth arrangement processing on the complete dentition image according to preset tooth arrangement rules to obtain an initial tooth arrangement result; and adjust the initial tooth arrangement result according to preset adjustment requirements to obtain an adjusted tooth arrangement result.

[0006] Method three is specifically as follows: obtaining a three-dimensional model of a triangular mesh of teeth for tooth arrangement; inputting the triangular mesh model of teeth into a pre-trained deep learning model to obtain the predicted tooth position of the tooth arrangement result. The deep learning model includes a first feature encoder that uses the triangular mesh three-dimensional model of teeth as input to obtain tooth shape features, a second feature encoder that uses the dentition point cloud as input to obtain dentition global features, and a feature decoder and mapper that obtains a predicted tooth arrangement result based on the tooth shape features and the dentition global features.

[0007] Method 4 is specifically as follows: adjusting the settings through manual experience, and different people may have different designs for a dental model. This method of tooth arrangement based on manual experience is inefficient and has large manual operation errors.

[0008] The above four methods cannot solve the problem of misengagement of the first, second, third and fourth model teeth (mainly located on the innermost four teeth on the left and right sides of the upper and lower jaws, four pairs on each side, a total of eight pairs) in the upper and lower jaws, which ultimately leads to inappropriate chewing function, uneven tooth wear, unstable occlusion, and affects the function of the temporomandibular joint. Therefore, the aesthetics and comfort of dental correction need to be further improved. Summary of the invention

[0009] The present invention aims to solve the problems of incorrect meshing of the first, second, third and fourth model teeth in the upper and lower jaws and unsightly tooth arrangement, and proposes a full-mouth automatic tooth arrangement method and system based on occlusal plane feature points to achieve automatic full-mouth tooth arrangement, while giving priority to perfect meshing of teeth, and optimizing the arrangement of teeth, thereby improving the aesthetic and neatness of the tooth arrangement results.

[0010] To achieve the above purpose, the technical solution adopted is:

[0011] A full-mouth automatic tooth arrangement method based on occlusal plane feature points, comprising:

[0012] Get dental model information, scan the upper and lower jaw dental models and automatically arrange the teeth, and further get the coordinates of the center of mass of each tooth, the first limit distance of each tooth, and the The characteristic points of the surface and the set directions in which movement is allowed;

[0013] Pairing the upper and lower teeth to obtain tooth pairs; aligning the z-axis of the centroid coordinates of each tooth pair, and roughly aligning the tooth pairs according to the first limit distance and the direction of allowed movement;

[0014] According to the point cloud data of the two teeth in the tooth pair, the objective function is constructed to perform iterative registration so that the tooth pair has the highest meshing degree and the greatest fit, thus completing the fine registration of the upper and lower teeth.

[0015] After completing the fine registration of the tooth pair, an objective function is constructed based on the alveolar crest line and the minimum distance between two adjacent teeth in the same jaw to optimize the tooth arrangement.

[0016] According to the full-mouth automatic tooth arrangement method based on occlusal plane feature points of the present invention, further, obtaining the coordinates of the center of mass of each tooth includes: first, obtaining the center of mass of each tooth based on an existing tooth database; and then establishing the position coordinates of each tooth in space based on the arranged upper and lower jaw tooth models.

[0017] According to the full-mouth automatic tooth arrangement method based on occlusal plane feature points of the present invention, further, the first limiting distance calculation process of each tooth in the x direction and the y direction is as follows:

[0018] For a tooth in the lower jaw, Face up, The direction of the surface is the z-axis direction, and the point cloud data is projected onto the occlusal plane to obtain a two-dimensional projection; first, the minimum and maximum values ​​of all points on the x-axis / y-axis are calculated, and the width in the x-direction / y-direction is calculated. This width is the maximum width of the tooth in the x-direction / y-direction, and half of this width value is used as the first limit distance of the tooth in the x-direction / y-direction; the calculation of the first limit distances of the remaining teeth in the mandible and the teeth in the maxilla is the same as the above calculation process.

[0019] According to the full-mouth automatic tooth arrangement method based on occlusal plane feature points of the present invention, further, each tooth is obtained The calculation process of the feature points of the surface is:

[0020] For the point cloud data of a tooth in the upper jaw, first divide the tooth into three equal parts in the z-axis direction and take The point cloud data at one-third of the tooth is obtained Point cloud data at one-third of the way;

[0021] Then use the PCA method to calculate the tooth The curvature values ​​of all points at one-third of the distance are selected, and the points with curvature values ​​greater than the set curvature threshold are screened out, and the distances from the screened points to the occlusal plane are calculated;

[0022] The point with the maximum distance among all the points filtered out is taken as the tooth The valley point on the surface, the point with the minimum distance is taken as the tooth The peak point on the surface;

[0023] The tooth The valley point and peak point of the tooth Feature points of the face; all teeth in the upper jaw The feature points of the surface are obtained by performing the same operation as above;

[0024] For mandibular teeth The calculation of the feature points of the surface is based on the occlusal plane extending a fixed distance to the mandibular direction for interception. The subsequent operation steps are the same as those for calculating the maxillary central teeth. The feature points of the faces are the same.

[0025] According to the full-mouth automatic tooth arrangement method based on occlusal plane feature points of the present invention, further, the upper and lower teeth are paired to obtain a tooth pair including: according to the centroid position of each tooth, the tooth with the closest centroid position is calculated, and the tooth is paired into a tooth pair, which represents two teeth in the upper and lower jaws that are meshed correspondingly.

[0026] According to the full-mouth automatic tooth arrangement method based on occlusal plane feature points of the present invention, further, the process of coarsely aligning the tooth pairs is: first, aligning the z-axis of the centroid coordinates of each tooth pair, and then moving the teeth in the upper and lower jaws of the tooth pair according to the allowed movement directions set in the upper and lower jaws, respectively, and the moving distance is less than the set first limit distance.

[0027] According to the full-mouth automatic tooth arrangement method based on the occlusal plane feature points of the present invention, further, by constructing an objective function to perform iterative registration so that the meshing degree of the tooth pair is the highest and the fitting degree is the greatest, the following contents are included:

[0028] According to the teeth obtained Point cloud data at one-third of the distance to calculate the fit of the current tooth pair A1: Align one tooth with two teeth The point cloud data of the contact area at one-third of the teeth is converted into a three-dimensional network model using a triangular mesh reconstruction algorithm. For each triangle, its area is calculated, and the areas of all triangles in the contact area are added together to obtain the contact degree A1. The larger the A1 value, the closer the teeth are to each other. The higher the contact between the surfaces;

[0029] According to the teeth obtained Point cloud data at one-third of the tooth pair to calculate the meshing degree of the current tooth pair A2: Calculate the maxillary teeth in the current tooth pair The peak feature points in the face feature points and the mandibular teeth The distance between the low and middle feature points of the face feature points and the calculation of the mandibular teeth The peak feature points in the face feature points and the maxillary teeth The distance between the low and middle feature points of the feature points of the surface is the sum of the two distances as the meshing degree A2 of the current tooth pair. The smaller the A2 value, the closer the two teeth are. The greater the degree of meshing of the faces;

[0030] For a tooth pair, construct the objective function J1:

[0031]

[0032] Among them, w1 and w2 are the weights of the parameters respectively; when J1 reaches the maximum value, the degree of meshing and fitting of the tooth pair is the highest.

[0033] According to the full-mouth automatic tooth arrangement method based on the occlusal plane feature points of the present invention, further, constructing an objective function based on the alveolar ridge top line and the minimum distance between two adjacent teeth in the same jaw includes:

[0034] First, move the teeth of the upper and lower jaws along the z-axis upward and downward respectively. The surface is in contact with the occlusal plane;

[0035] Then, by constructing the objective function J2, the position coordinates of each tooth in space are adjusted by iterative movement on the top line of the maxillary / mandibular alveolar ridge, so that the deviation between the tooth and the top line of the alveolar ridge is minimized and the consistency of the distance between two adjacent teeth in the same jaw is maximized. When the value of the objective function J2 reaches the minimum, the optimized tooth arrangement is completed.

[0036] According to the full-mouth automatic tooth arrangement method based on the occlusal plane feature points of the present invention, further, the deviation degree B1 between the tooth and the alveolar ridge top line is calculated: the maxillary alveolar ridge top line is projected onto the occlusal plane, the z-axis coordinate of the centroid point of each tooth in the maxilla is projected onto the occlusal plane, and the sum of the position coordinates of the centroid point of each tooth projected onto the occlusal plane and the shortest distance of the alveolar ridge top line projected onto the occlusal plane is calculated, which is recorded as B1. The larger the value, the more the position coordinates of the centroid point of the tooth in the maxillary teeth deviate from the maxillary alveolar ridge top line;

[0037] Calculate the consistency B2 of the distance between two adjacent teeth in the same jaw: Calculate the distance between the centroids of two adjacent teeth after the z-axis coordinates of the centroids of each tooth in the maxillary teeth are projected onto the occlusal plane, and further calculate the variance of the distance between the centroids of two adjacent teeth, recorded as B2. The larger the value, the greater the difference in the distance between the two adjacent teeth in the maxillary teeth, and the poorer the consistency of the maxillary tooth arrangement;

[0038] The calculation of the deviation between the teeth and the dental ridge line and the consistency of the distance between two adjacent teeth in the mandibular teeth is consistent with the calculation of the deviation between the teeth and the dental ridge line and the consistency of the distance between two adjacent teeth in the maxillary teeth, and they are recorded as B3 and B4 respectively;

[0039] The objective function J2 is constructed as follows:

[0040] J2=w3(B1+B2)+w4(B3+B4)

[0041] Among them, w3 and w4 are the weights of the parameters respectively.

[0042] Furthermore, the present invention also provides a full-mouth automatic tooth arrangement system based on occlusal plane feature points, which is used to implement the full-mouth automatic tooth arrangement method based on occlusal plane feature points as described above, and the system comprises:

[0043] The automatic tooth arrangement module is used to obtain dental model information, scan the upper and lower jaw dental models and automatically arrange the teeth, and further obtain the coordinates of the centroid of each tooth, the first limit distance of each tooth, and the The characteristic points of the surface and the set directions in which movement is allowed;

[0044] A coarse registration module is used to match the upper and lower teeth to obtain tooth pairs; align the z-axis coordinates of the centroid point of each tooth pair, and coarsely register the tooth pairs according to the first limit distance and the direction of allowed movement;

[0045] The fine registration module is used to perform iterative registration based on the point cloud data of the two teeth in the tooth pair by constructing an objective function to achieve the highest meshing degree and the greatest fit of the tooth pair, thus completing the fine registration of the upper and lower teeth;

[0046] The tooth arrangement optimization module is used to construct an objective function based on the alveolar ridge top line and the minimum distance between two adjacent teeth in the same jaw after completing the fine alignment of the tooth pair to optimize the tooth arrangement.

[0047] The beneficial effects achieved by adopting the above technical solution are:

[0048] 1. Improve efficiency: The present invention reduces the time of manual operation and improves work efficiency by automating tooth arrangement and registration. The automated tooth arrangement function can automatically generate an ideal tooth arrangement by processing the dental model data using computer software. This allows dentists to handle complex tooth arrangement problems with higher accuracy and efficiency, allowing more patients to receive timely treatment.

[0049] 2. Enhanced accuracy: By calculating the center of mass of the tooth, the first limit distance, and the tooth The characteristic points of the surface ensure the accuracy of tooth arrangement and registration, which helps to improve the accuracy of tooth correction and reduce errors.

[0050] 3. Improve patient comfort: First, the coarse alignment of the teeth is performed to ensure accurate matching of the upper and lower teeth; then the fine alignment process is iteratively adjusted to optimize the occlusal relationship of the upper and lower teeth. Accurate tooth alignment can improve the comfort of the bite and reduce the discomfort that may occur during tooth correction.

[0051] 4. Data-driven decision-making: Utilize information from existing dental databases for analysis and decision-making, making the process of tooth alignment and registration more scientific and data-driven, thereby providing personalized treatment plans.

[0052] 5. Reduce errors and conflicts: During the fine registration process, by constructing the objective function and making iterative adjustments, the maximum fit between the upper and lower teeth is ensured, reducing conflicts between teeth and penetration.

[0053] 6. Improve the aesthetics of the upper and lower jaw tooth arrangement models: Further optimize the tooth arrangement after fine alignment to ensure the aesthetics of the tooth model, so that the final tooth arrangement meets the functional requirements and is aesthetically pleasing. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention, wherein the drawings are only used to illustrate some embodiments of the present invention, but not to limit all embodiments of the present invention thereto.

[0055] Figure 1 is a schematic flow chart of a full-mouth automatic tooth arrangement method based on occlusal plane feature points according to an embodiment of the present invention;

[0056] Figure 2 Schematic diagram of a maxillary dental model and a mandibular dental model according to an embodiment of the present invention;

[0057] Figure 3 is a schematic diagram of a single tooth according to an embodiment of the present invention;

[0058] Figure 4 is a schematic diagram of arranged upper and lower jaw teeth according to an embodiment of the present invention;

[0059] Figure 5 is a coordinate diagram of the position of the centroid of each tooth in space according to an embodiment of the present invention;

[0060] Figure 6 The embodiment of the present invention is Schematic diagram of point cloud data at one-third of the distance;

[0061] Figure 7 is a diagram showing the position relationship between a tooth in the upper jaw and the occlusal plane according to an embodiment of the present invention;

[0062] Figure 8 is a schematic diagram of the alveolar crest line according to an embodiment of the present invention; DETAILED DESCRIPTION

[0063] The following will be combined with the drawings of specific embodiments of the present invention to clearly and completely describe the exemplary scheme of the embodiment of the present invention. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field.

[0064] like Figure 1 As shown, this embodiment discloses a full-mouth automatic tooth arrangement method based on occlusal plane feature points, which includes the following contents:

[0065] Step S1, obtain dental model information, scan the upper and lower jaw dental models and automatically arrange the teeth, and further obtain the centroid coordinates of each tooth, the first limit distance of each tooth, and the The characteristic points of the surface and the set directions in which movement is allowed.

[0066] (1) Automatic tooth arrangement of upper and lower jaws: The dentist obtains the patient's oral scan data (such as CT scan, oral impression, etc.) to obtain the maxillary and mandibular dental molds (such as Figure 2 The dental model data is imported into the computer software. The software is based on the existing dental database (the dental database refers to the established finished single teeth, such as Figure 3 As shown in the figure), the dental model data is further imported to automatically identify and analyze the position, size and shape of each tooth, and then automatically arrange the teeth according to the ideal position of each tooth in the dentition, so as to automatically obtain the arranged upper and lower jaw teeth. Figure 4 shown.

[0067] (2) Based on the existing tooth database, calculate the position coordinates of the center of mass of each tooth in space, calculate the first limit distance, limit movement direction and each tooth Feature points of a surface.

[0068] ①Define the positional relationship between each tooth and the spatial coordinate system

[0069] The method for obtaining the position coordinates of the centroid of each tooth in space has the following process: firstly, the centroid of each tooth is directly obtained according to the existing tooth database, then the tooth models of the upper and lower jaws arranged in step (1) in step S1 are obtained, and finally the position coordinates of each tooth in space are established. Figure 5 The blue in the middle is the z-axis pointing upward, the red is the x-axis, and the green is the y-axis. The x-axis and y-axis are on the horizontal plane. It should be noted that Figure 5 It is 3D triangular mesh data, not point cloud data, and is only used to understand the coordinates of the teeth.

[0070] ②Get the first limit distance

[0071] The calculation process of the first limit distance of each tooth in the x-direction and y-direction is as follows:

[0072] Take the y direction as an example (the x direction can refer to the calculation process of the y direction); for a tooth in the lower jaw, Face up, The direction of the plane is the z-axis direction, that is, the positive direction of the z-axis, and the point cloud data is projected onto the occlusal plane. Ignore the z-axis coordinates and only keep the x- and y-axis coordinates. In this way, a two-dimensional projection of the three-dimensional point cloud data of the tooth on the horizontal plane can be obtained. In the projected two-dimensional point cloud, first calculate the minimum and maximum values ​​of all points on the y-axis, and calculate the width in the y direction. This width is the maximum width of the tooth in the y direction, and half of the width value is used as the first limit distance of the tooth in the y direction. The calculation of the first limit distance of the remaining teeth in the mandible and the teeth in the maxilla is the same as the above calculation process.

[0073] ③Get the direction in which movement is allowed

[0074] Through the existing tooth database, each tooth including the minimum distance between teeth and the allowed movement direction can be directly obtained. This information can be obtained by accessing the existing tooth database.

[0075] ④Get each tooth Feature points of the face

[0076] For one tooth in the upper jaw The calculation process of the feature points of the surface is:

[0077] For the point cloud data of a tooth in the upper jaw, first divide the tooth into three equal parts in the z-axis direction and take The point cloud data at one-third of the tooth is obtained. Point cloud data at one third.

[0078] Then use the PCA method to calculate the tooth The curvature values ​​of all points at one-third of the occlusal plane are calculated by setting a curvature threshold, filtering out points whose curvature values ​​are greater than the set curvature threshold, and calculating the distance from the filtered points to the occlusal plane, such as Figure 7 shown.

[0079] The point with the maximum distance among all the points filtered out is taken as the tooth The valley point on the surface, the point with the minimum distance is taken as the tooth The peak point on the surface.

[0080] The tooth The valley point and peak point of the tooth Feature points of the face, all teeth in the upper jaw The feature points of the surface are obtained by performing the same operation as above.

[0081] Of course, you can also adjust the settings to divide a tooth into several equal parts according to the actual situation on site. If you divide the tooth into four parts, that is, cut Point cloud at one quarter, while ensuring that the selected The point cloud at one quarter of the tooth All feature points on the surface are included.

[0082] For mandibular teeth The calculation of the feature points of the surface is based on the occlusal plane extending a fixed distance to the mandibular direction for interception. The subsequent operation steps are the same as those for calculating the maxillary central teeth. The feature points of the faces are the same.

[0083] Among them, the setting of the fixed extension distance of the upper and lower jaws can be adjusted and set by experience; the setting of the curvature threshold of the upper and lower jaws can also be adjusted and set by experience.

[0084] At this point, we have obtained the teeth arranged in the upper and lower jaws, the coordinates of the center of mass of each tooth, the first limit distance of each tooth, the limit movement direction and each tooth. Feature points of a surface.

[0085] Step S2, pairing the upper and lower teeth to obtain tooth pairs; aligning the z-axis of the centroid coordinates of each tooth pair, and roughly aligning the tooth pairs according to the first limit distance and the direction of allowed movement.

[0086] (1) Pair the upper and lower teeth into tooth pairs.

[0087] Since the three-dimensional models of the upper and lower jaws in the oral cavity have been registered when the oral cavity model is scanned using a three-dimensional imaging device, that is, the alignment of the upper and lower jaw models has been completed, the scanned upper and lower jaw models have restored the real oral state, and the tooth arrangement of the upper and lower jaws has been completed in step (1) of step S1, and the teeth of the upper and lower jaws can be directly obtained to complete the tooth arrangement of the upper and lower jaws. Then, the teeth arranged in the upper and lower jaws need to be paired into tooth pairs, which represent two teeth corresponding to the upper and lower jaws that are meshed.

[0088] The pairing process for a tooth pair is as follows: according to the centroid position of each tooth, the tooth with the closest centroid position is calculated and paired into a tooth pair.

[0089] Exemplarily, firstly, the distance between the position coordinates of the center of mass of a tooth in the upper jaw and the position coordinates of the center of mass of all teeth in the lower jaw is calculated, and the tooth with the smallest distance value to the teeth in the lower jaw is taken as a tooth pair, thus completing the tooth pairing.

[0090] (2) Rough alignment of teeth

[0091] After the teeth in the upper and lower jaws are matched into a tooth pair, for a tooth pair, there is the following rough matching process: first, the center of mass points of the teeth in the upper and lower jaws are moved to the same z-axis, and then according to the allowed movement directions set in the upper and lower jaw teeth, the teeth in the upper and lower jaws of the tooth pair are moved respectively, and the moving distance must be less than the set first limit distance.

[0092] For example, if the allowed direction of movement of the teeth in the upper jaw in a tooth pair is toward the inside of the oral cavity, and the allowed direction of movement of the teeth in the lower jaw is toward the outside of the oral cavity, the tooth pair on the same z-axis moves in the xy plane according to the allowed directions of movement.

[0093] At this point, the rough alignment of the upper and lower jaw teeth is completed, and the upper and lower jaw tooth models after rough alignment are obtained.

[0094] Step S3: Based on the point cloud data of the two teeth in the tooth pair, an objective function is constructed to perform iterative registration so that the tooth pair has the highest meshing degree and the greatest fit, thereby completing the fine registration of the upper and lower teeth.

[0095] (1) Calculate the characteristic parameters of the tooth pair

[0096] Fine alignment is performed based on the roughly aligned teeth, by continuously moving one tooth to center the two teeth in the xyz directions, so that the teeth are centered on the maxillary teeth. The peak feature points in the face feature points and the mandibular teeth Among the feature points of the face, the distance between the valley feature points is the closest, and the mandibular teeth The peak feature points in the face feature points and the maxillary teeth The distance between the valley feature points of the face is the closest, and the teeth of the upper and lower jaws are The face fit is the greatest, and the upper and lower teeth in the tooth pair fit best, completing the fine alignment. The fine alignment process is as follows:

[0097] ① According to step (2) in step S1, two teeth in the center of the tooth can be obtained. Point cloud data at one third.

[0098] ②According to the teeth obtained Point cloud data at one-third of the distance to calculate the degree of fit of the current tooth pair , the calculation process is as follows:

[0099] For two teeth in a tooth pair The point cloud data at one-third of the maxillary teeth was obtained by the nearest neighbor search algorithm KD tree algorithm. For each point in the point cloud at one-third, find its position on the mandibular teeth By setting the point cloud distance threshold, when two teeth The point pairs whose closest points in the point cloud data at one-third of the distance are smaller than the distance threshold are considered to be the contact area. The setting of the point cloud distance threshold can be adjusted and set by experience.

[0100] Align one tooth to two teeth The point cloud data of the contact area at one-third of the teeth is converted into a three-dimensional network model using a triangular mesh reconstruction algorithm (such as Poisson reconstruction or marching cube algorithm). The purpose of meshing is to convert the point cloud data into a set of connected triangles that form a surface. For each triangle, its area is calculated, and the areas of all triangles in the contact area are added together to obtain the contact degree A1. The size of the A1 value reflects the degree of contact. The larger the value, the closer the teeth are to each other. The higher the contact degree of the surface, the better the contact degree. The expression of contact degree A1 is as follows:

[0101]

[0102] in, are the two side vectors of the triangle, Represents the area of ​​a triangle, i represents the area of ​​the i-th triangle, and n is the total number of triangles in the contact area.

[0103] ③According to the teeth obtained The point cloud data at one-third of the tooth is used to calculate the meshing degree A2 of the current tooth pair. The calculation process is as follows:

[0104] Calculate the current tooth alignment of the maxillary teeth The peak feature points in the face feature points and the mandibular teeth The distance between the low and middle feature points of the face feature points and the calculation of the mandibular teeth The peak feature points in the face feature points and the maxillary teeth The distance between the low and middle feature points of the feature points of the surface is the sum of the two distances as the meshing degree A2 of the current tooth pair. The value of A2 reflects the meshing degree. The smaller the value, the closer the two teeth are. The greater the degree of meshing of the faces.

[0105] (2) Construct the objective function and iteratively adjust to complete the fine registration

[0106] For a tooth pair, construct the objective function J1, and according to the first limit distance, the limit movement direction, and the position coordinates of the center of mass of the upper and lower teeth, continuously move and adjust the relative position of the upper and lower teeth in the xyz direction in a tooth pair, and move and adjust the meshing effect of the tooth pair by continuous calculation. When the objective function reaches the maximum value, the meshing degree of the tooth pair is the highest and the fit is the greatest, and the fine alignment of the tooth pair is completed at this time. And in the process of moving in the xyz direction, the teeth in the tooth pair are continuously detected for collision to avoid incorrect contact of the tooth pair after fine alignment. Construct the objective function J1 as follows:

[0107]

[0108] Among them, w1 and w2 are the weights of the parameters respectively.

[0109] Exemplarily, for a tooth pair after rough alignment, according to the set limiting direction, the first limiting distance and the coordinate position of the centroid of the two teeth in the current tooth pair in the tooth pair. For the maxillary teeth, randomly select a direction and a distance in the three directions of xyz to move the maxillary teeth in a certain step length, calculate the value of the objective function J1, randomly select a direction and a distance again to move in a certain step length, and calculate the value of the objective function J1 again. If the J1 value after the current movement is less than the J1 value after the previous movement, move in the direction selected in the current time in the opposite direction by a certain step length or randomly select a direction in the other two directions to move. During the movement, collision detection is performed in real time. When a collision is detected, the current movement is not executed, and the direction selected in the current time is moved in the opposite direction by a certain step length or randomly selects a direction in the other two directions to move. When the value of the objective function J1 reaches the maximum value or is greater than a certain threshold value set, the iterative movement is completed. At this time, the meshing degree of the tooth pair is the highest and the fitting degree is the largest, and the fine alignment of the tooth pair is completed.

[0110] Step S4: After completing the fine registration of the tooth pair, an objective function is constructed according to the alveolar ridge top line and the minimum distance between two adjacent teeth in the same jaw to optimize the tooth arrangement.

[0111] The objective function is used to optimize the distance between the upper and lower teeth to maximize the consistency of the arrangement, thereby achieving a neat and beautiful tooth arrangement. The main goal of this method is to improve the consistency and inefficiency that may exist in the manual tooth arrangement process by iteratively adjusting the distance between teeth.

[0112] (1) First, move the teeth of the upper and lower jaws upward and downward along the z-axis respectively. The surface is in contact with the occlusal plane.

[0113] For example, for the maxilla, the distance between the occlusal plane and the centroid of each tooth in the maxilla is detected, and the centroid of each tooth is combined with the The distance from the farthest point on the facial surface is to move the teeth in the upper jaw upward in the mouth so that the teeth in the upper jaw The farthest point of the facial surface is in contact with the occlusal plane, and the teeth in the mandible are moved downward in the mouth by the above operation.

[0114] (2) Optimize tooth arrangement

[0115] Then, by constructing the objective function J2, the position coordinates of each tooth in space are adjusted by iterative movement on the maxillary (or mandibular) alveolar ridge top line, so that the deviation between the tooth and the alveolar ridge top line is minimized and the consistency of the distance between two adjacent teeth in the same jaw is maximized. When the value of the objective function J2 reaches the minimum, the optimized tooth arrangement is completed. It should be noted that in the process of optimizing the tooth arrangement, the relative distance between each tooth pair remains unchanged. Figure 8 This is a schematic diagram of the alveolar crest line. The curve formed by the brown line and the blue ball is the alveolar crest line, also known as the tooth ridge line. Figure 8 It is 3D triangular mesh data, which is only used to understand the top line of the alveolar ridge, not point cloud data.

[0116] ① Calculate the degree of deviation between the tooth and the alveolar ridge top line

[0117] Project the maxillary alveolar ridge top line onto the occlusal plane, project the z-axis coordinates of the centroid of each tooth in the maxilla (the xy-axis values ​​remain unchanged) onto the occlusal plane, calculate the sum of the position coordinates of the centroid of each tooth projected onto the occlusal plane and the shortest distance of the alveolar ridge top line projected onto the occlusal plane, and record it as B1. The larger the value, the more the position coordinates of the centroid of the teeth in the maxillary teeth deviate from the maxillary alveolar ridge top line. This further indicates that the maxillary tooth arrangement effect is worse. The expression of B1 is as follows:

[0118]

[0119] Where, d k It indicates the shortest distance between the position coordinates of the center of mass of the kth tooth projected onto the occlusal plane and the top line of the alveolar ridge projected onto the occlusal plane among all the teeth; m indicates that there are m teeth in the current mouth.

[0120] ②Calculate the consistency of the distance between two adjacent teeth in the same jaw

[0121] The distance between the centroids of two adjacent teeth after the z-axis coordinate of the centroid of each tooth in the maxillary teeth is projected onto the occlusal plane is calculated, and the variance of the distance between the centroids of two adjacent teeth is further calculated, which is recorded as B2. The larger the value, the greater the difference in the distance between the two adjacent teeth in the maxillary teeth, and the poorer the consistency of the maxillary tooth arrangement.

[0122] Based on the distance between each tooth, the formula for B2 is as follows:

[0123]

[0124] Where, X j represents the distance between the centroids of the jth two adjacent teeth; represents the mean of all distances; N represents that there are N pairs of adjacent teeth.

[0125] The calculation of the degree of deviation between the teeth and the dental ridge line and the consistency of the distance between two adjacent teeth in the mandibular teeth is consistent with the calculation of the degree of deviation between the teeth and the dental ridge line and the consistency of the distance between two adjacent teeth in the maxillary teeth, and are recorded as B3 and B4 respectively.

[0126] The objective function J2 is constructed as follows:

[0127] J2=w3(B1+B2)+w4(B3+B4)

[0128] Among them, w3 and w4 are the weights of the parameters respectively.

[0129] Exemplarily, for the oral cavity and tooth model that has been finely aligned, while keeping the relative positions of the upper and lower teeth in each tooth pair unchanged. First, randomly select a tooth in the upper jaw, randomly select a direction on the xy axis of the tooth and move it according to a certain step length, calculate the value of the objective function J2, randomly select a tooth in the upper jaw again, randomly select a direction on the xy axis of the tooth and move it according to a certain step length, and calculate the value of the objective function J2 again. If the current J2 value is larger than the previous J2 value, move in the opposite direction of the current selected movement direction, or randomly select another tooth and randomly select a direction to move with a certain step length. When the value of the objective function J2 reaches the minimum value or is less than a certain set threshold, the iterative movement is completed. At this time, the deviation between the tooth and the dental ridge is minimized, and the consistency of the distance between two adjacent teeth in the same jaw is maximized. The tooth arrangement optimization is completed.

[0130] Arrange the maxillary teeth according to standard rules so that in the full-mouth tooth arrangement, the meshing of each pair of teeth is prioritized while also satisfying the aesthetics of the upper and lower jaw tooth arrangement models.

[0131] At this point, the automatic tooth arrangement is completed.

[0132] Corresponding to the above method, this embodiment also discloses a full-mouth automatic tooth arrangement system based on occlusal plane feature points, comprising:

[0133] The automatic tooth arrangement module is used to obtain dental model information, scan the upper and lower jaw dental models and automatically arrange the teeth, and further obtain the coordinates of the centroid of each tooth, the first limit distance of each tooth, and the The characteristic points of the surface and the set directions in which movement is allowed.

[0134] The coarse registration module is used to match the upper and lower teeth to obtain tooth pairs; align the z-axis coordinates of the centroid point of each tooth pair, and coarsely align the tooth pairs according to the first limit distance and the direction of allowed movement.

[0135] The fine registration module is used to perform iterative registration based on the point cloud data of the two teeth in the tooth pair by constructing an objective function to achieve the highest degree of meshing and fit of the tooth pair, thereby completing the fine registration of the upper and lower teeth.

[0136] The tooth arrangement optimization module is used to construct an objective function based on the alveolar ridge top line and the minimum distance between two adjacent teeth in the same jaw after completing the fine alignment of the tooth pair to optimize the tooth arrangement.

[0137] Unless otherwise specifically stated, the relative steps, numerical expressions and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0138] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0139] The units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person of ordinary skill in the art may use different methods to implement the described functions for each specific application, but such implementation is not considered to be beyond the scope of the present invention.

[0140] Those skilled in the art will appreciate that all or part of the steps in the above method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, a disk or an optical disk. Optionally, all or part of the steps in the above embodiment can also be implemented using one or more integrated circuits, and accordingly, each module / unit in the above embodiment can be implemented in the form of hardware or in the form of software function modules. The present invention is not limited to any specific form of combination of hardware and software.

[0141] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A full-mouth automatic tooth arrangement method based on occlusal plane feature points, characterized in that: Include: Get dental model information, scan the upper and lower jaw dental models and automatically arrange the teeth, and further get the coordinates of the center of mass of each tooth, the first limit distance of each tooth, and the The characteristic points of the surface and the set directions in which movement is allowed; Pairing the upper and lower teeth to obtain tooth pairs; aligning the z-axis of the centroid coordinates of each tooth pair, and roughly aligning the tooth pairs according to the first limit distance and the direction of allowed movement; According to the point cloud data of the two teeth in the tooth pair, the objective function is constructed to perform iterative registration so that the tooth pair has the highest meshing degree and the greatest fit, thus completing the fine registration of the upper and lower teeth. After completing the fine registration of the tooth pair, an objective function is constructed based on the alveolar crest line and the minimum distance between two adjacent teeth in the same jaw to optimize the tooth arrangement.

2. The full-mouth automatic tooth arrangement method based on occlusal plane feature points according to claim 1, characterized in that: Obtaining the coordinates of the centroid of each tooth includes: firstly obtaining the centroid of each tooth according to an existing tooth database; and then establishing the position coordinates of each tooth in space according to the arranged upper and lower jaw tooth models.

3. The full-mouth automatic tooth arrangement method based on occlusal plane feature points according to claim 2, characterized in that: The calculation process of the first limit distance of each tooth in the x-direction and y-direction is as follows: For a tooth in the lower jaw, Face up, The direction of the surface is the z-axis direction, and the point cloud data is projected onto the occlusal plane to obtain a two-dimensional projection; first, the minimum and maximum values ​​of all points on the x-axis / y-axis are calculated, and the width in the x-direction / y-direction is calculated. This width is the maximum width of the tooth in the x-direction / y-direction, and half of this width value is used as the first limit distance of the tooth in the x-direction / y-direction; the calculation of the first limit distances of the remaining teeth in the mandible and the teeth in the maxilla is the same as the above calculation process.

4. The full-mouth automatic tooth arrangement method based on occlusal plane feature points according to claim 2, characterized in that: Get every tooth The calculation process of the feature points of the surface is: For the point cloud data of a tooth in the upper jaw, first divide the tooth into three equal parts in the z-axis direction and take The point cloud data at one-third of the tooth is obtained Point cloud data at one-third of the way; Then use the PCA method to calculate the tooth The curvature values ​​of all points at one-third of the distance are selected, and the points with curvature values ​​greater than the set curvature threshold are screened out, and the distances from the screened points to the occlusal plane are calculated; The point with the maximum distance among all the points filtered out is taken as the tooth The valley point on the surface, the point with the minimum distance is taken as the tooth The peak point on the surface; The tooth The valley point and peak point of the tooth Feature points of the face; all teeth in the upper jaw The feature points of the surface are obtained by performing the same operation as above; For mandibular teeth The calculation of the feature points of the surface is based on the occlusal plane extending a fixed distance to the mandibular direction for interception. The subsequent operation steps are the same as those for calculating the maxillary central teeth. The feature points of the faces are the same.

5. The full-mouth automatic tooth arrangement method based on occlusal plane feature points according to claim 1, characterized in that: Pairing the upper and lower teeth to obtain a tooth pair includes: calculating the tooth closest to the center of mass of each tooth according to the center of mass of the tooth, and pairing them into a tooth pair, which represents two teeth in the upper and lower jaws that mesh correspondingly.

6. The full-mouth automatic tooth arrangement method based on occlusal plane feature points according to claim 1, characterized in that: The process of coarse alignment of tooth pairs is as follows: first align the z-axis coordinates of the centroid of each tooth pair, and then move the teeth in the upper and lower jaws of the tooth pair according to the allowed movement directions set in the upper and lower jaw teeth, and the moving distance is less than the set first limit distance.

7. The full-mouth automatic tooth arrangement method based on occlusal plane feature points according to claim 4, characterized in that: By constructing an objective function for iterative registration, the tooth pair is aligned to the highest degree of meshing and the greatest degree of fit, including the following: According to the teeth obtained Point cloud data at one-third of the distance to calculate the fit of the current tooth pair A1: Align one tooth to the center of two teeth The point cloud data of the contact area at one-third of the teeth is converted into a three-dimensional network model using a triangular mesh reconstruction algorithm. For each triangle, its area is calculated, and the areas of all triangles in the contact area are added together to obtain the contact degree A1. The larger the A1 value, the closer the teeth are to each other. The higher the contact between the surfaces; According to the teeth obtained Point cloud data at one-third of the tooth pair to calculate the degree of meshing of the current tooth pair : Calculate the maxillary teeth in the current tooth alignment The peak feature points in the face feature points and the mandibular teeth The distance between the low and middle feature points of the face feature points and the calculation of the mandibular teeth The peak feature points in the face feature points and the maxillary teeth The distance between the valley feature points of the surface feature points, and the sum of the two distances is used as the meshing degree of the current tooth pair , The smaller the value, the more teeth The greater the degree of meshing of the faces; For a tooth pair, construct the objective function J1: Among them, w1 and w2 are the weights of the parameters respectively; when J1 reaches the maximum value, the degree of meshing and fitting of the tooth pair is the highest.

8. The full-mouth automatic tooth arrangement method based on occlusal plane feature points according to claim 2, characterized in that: The objective function is constructed based on the alveolar ridge top line and the minimum distance between two adjacent teeth in the same jaw, including: First, move the teeth of the upper and lower jaws along the z-axis upward and downward respectively. The surface is in contact with the occlusal plane; Then, by constructing the objective function J2, the position coordinates of each tooth in space are adjusted by iterative movement on the top line of the maxillary / mandibular alveolar ridge, so that the deviation between the tooth and the top line of the alveolar ridge is minimized and the consistency of the distance between two adjacent teeth in the same jaw is maximized. When the value of the objective function J2 reaches the minimum, the optimized tooth arrangement is completed.

9. The full-mouth automatic tooth arrangement method based on occlusal plane feature points according to claim 8, characterized in that: Calculate the degree of deviation B1 between the teeth and the alveolar ridge top line: project the maxillary alveolar ridge top line onto the occlusal plane, project the z-axis coordinate of the centroid of each tooth in the maxilla onto the occlusal plane, calculate the sum of the position coordinates of the centroid of each tooth projected onto the occlusal plane and the shortest distance of the alveolar ridge top line projected onto the occlusal plane, and record it as B1. The larger the value, the more the position coordinates of the centroid of the teeth in the maxillary teeth deviate from the maxillary alveolar ridge top line; Calculate the consistency B2 of the distance between two adjacent teeth in the same jaw: Calculate the distance between the centroids of two adjacent teeth after the z-axis coordinates of the centroids of each tooth in the maxillary teeth are projected onto the occlusal plane, and further calculate the variance of the distance between the centroids of two adjacent teeth, recorded as B2. The larger the value, the greater the difference in the distance between the two adjacent teeth in the maxillary teeth, and the poorer the consistency of the maxillary tooth arrangement; The calculation of the deviation between the teeth and the dental ridge line and the consistency of the distance between two adjacent teeth in the mandibular teeth is consistent with the calculation of the deviation between the teeth and the dental ridge line and the consistency of the distance between two adjacent teeth in the maxillary teeth, and they are recorded as B3 and B4 respectively; The objective function J2 is constructed as follows: J2=w3(B1+B2)+w4(B3+B4) Among them, w3 and w4 are the weights of the parameters respectively.

10. A full-mouth automatic tooth arrangement system based on occlusal plane feature points, characterized in that: The system is used to implement the full-mouth automatic tooth arrangement method based on occlusal plane feature points as described in any one of claims 1 to 9, comprising: The automatic tooth arrangement module is used to obtain dental model information, scan the upper and lower jaw dental models and automatically arrange the teeth, and further obtain the coordinates of the centroid of each tooth, the first limit distance of each tooth, and the The characteristic points of the surface and the set directions in which movement is allowed; A coarse registration module is used to match the upper and lower teeth to obtain tooth pairs; align the z-axis coordinates of the centroid point of each tooth pair, and coarsely register the tooth pairs according to the first limit distance and the direction of allowed movement; The fine registration module is used to perform iterative registration based on the point cloud data of the two teeth in the tooth pair by constructing an objective function to achieve the highest meshing degree and the greatest fit of the tooth pair, thus completing the fine registration of the upper and lower teeth; The tooth arrangement optimization module is used to construct an objective function based on the alveolar ridge top line and the minimum distance between two adjacent teeth in the same jaw after completing the fine alignment of the tooth pair to optimize the tooth arrangement.

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