A method for generating a tooth preparation grinding path

Abstract

The application discloses a kind of generation methods of dental preparation grinding path, it is related to dental prosthetic field, including obtaining to-be-ground tooth point cloud model, preparation body point cloud model;To-be-ground tooth point cloud model is aligned with preparation body point cloud model;Preparation body point cloud model is inflated, and preparation body point cloud model after inflation is obtained;Based on preparation body point cloud model after inflation and to-be-ground tooth point cloud model, extract path reference area, denoising;Path reference area is divided into closed loop area, open loop area;Closed loop area grinding path is generated;Open loop area grinding path is generated;Open loop area grinding path is added after closed loop area grinding path, and dental preparation grinding path is obtained.The application is used to solve the problem that the grinding path planning for dental preparation in the prior art depends on the subjective experience of the attending physician, lacks automated and standardized path planning method, to achieve the purpose of providing a standardized path generation method for automated dental preparation operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of dental prosthetics, in particular to a method for generating a tooth preparation grinding path. BACKGROUND

[0002] In the field of dental prosthetics, tooth preparation is a core step to create an accurate space and form for a restoration (such as a full crown, inlay, veneer, etc.). The goal is to safely and efficiently remove an appropriate amount of tooth structure on the affected tooth to form a preparation body with specific geometric requirements (such as a specified axial wall convergence, clear edge shoulder, and smooth continuous surface).

[0003] Traditional tooth preparation is mostly completed by hand by the doctor, relying heavily on the doctor's experience and skills, and has problems such as excessive subjectivity, large precision fluctuations, low efficiency, insufficient standardization, easy damage to adjacent teeth or dental pulp, and strong patient discomfort. With the development of digital oral technology, dental robots and automated grinding in the field of tooth preparation have been proposed to achieve more accurate and efficient operations.

[0004] For tooth preparation, the grinding path directly determines the preparation effect of the preparation body. However, in the prior art, standardized path planning for tooth preparation cannot be carried out, and it still relies heavily on the subjective experience of the attending physician, which seriously hinders the automation and standardization of tooth preparation, and limits the clinical application of automated tooth preparation technology. SUMMARY

[0005] The present application provides a method for generating a tooth preparation grinding path to solve the problem of relying on the subjective experience of the attending physician for grinding path planning of tooth preparation in the prior art, lack of automated and standardized path planning method, and achieve the purpose of providing a standardized path generation method for automated tooth preparation.

[0006] The present application is achieved by the following technical solutions:

[0007] A method for generating a tooth preparation grinding path, comprising the following steps:

[0008] Obtain a tooth point cloud model to be ground and a preparation body point cloud model; align the tooth point cloud model to be ground and the preparation body point cloud model in the same coordinate system;

[0009] Inflate the preparation body point cloud model by a distance r to obtain an inflated preparation body point cloud model; wherein r is the radius of the bur used for tooth preparation;

[0010] Based on the inflated preparation body point cloud model and the tooth point cloud model to be ground, extract a path reference area and denoise;

[0011] Divide the path reference area into a closed loop area and an open loop area;

[0012] Generate a closed loop area grinding path;

[0013] Generate an open loop area grinding path;

[0014] Add the open loop area grinding path after the closed loop area grinding path to obtain a tooth preparation grinding path.

[0015] The prior art for the tooth preparation grinding path planning relies on the subjective experience of the attending physician for manual operation, and lacks an automatic and standardized path planning method, which also restricts the use of robots or other automatic devices for tooth automatic preparation. In order to overcome the above problems, the present application provides a tooth preparation grinding path generation method.

[0016] The method first acquires a to-be-ground tooth point cloud model and a preparation body point cloud model. For the automatic operation of tooth preparation, the purpose is to generate a grinding path between the two models, and to grind the to-be-ground tooth point cloud model into the preparation body point cloud model through the grinding path. Therefore, the present application first aligns the to-be-ground tooth point cloud model and the preparation body point cloud model in the same coordinate system, then inflates the preparation body point cloud model by a distance of a burr radius, and then places the to-be-ground tooth point cloud model and the inflated preparation body point cloud model in the same Cartesian coordinate system, and extracts a path reference area based on the inflated preparation body point cloud model. Then, the path reference area is denoised, and the path reference area is divided into a closed loop area and an open loop area, and then the grinding paths of the closed loop area and the open loop area are respectively generated by calculation, and finally the grinding path of the open loop area is written after the grinding path of the closed loop area, and a complete tooth preparation grinding path is obtained.

[0017] Those skilled in the art should understand that the closed loop area grinding path in the present application refers to a closed path connected at the beginning and the end, and the open loop area grinding path refers to an open path not connected at the beginning and the end. In addition, the acquisition and alignment of point cloud data in the present application can be realized by using the prior art, and will not be described in detail here.

[0018] In the present application, the purpose of inflating the preparation body point cloud model by a distance r is to compensate for the size of the grinding tool; the burr is a special instrument for the department of stomatology, and existing tungsten steel burrs or diamond burrs can be used.

[0019] The application creatively provides a standardized and normalized grinding path generation method for tooth preparation, overcomes the technical problems of excessive subjectivity, large precision fluctuation, low efficiency, insufficient standardization, and easy damage to adjacent teeth or dental pulp caused by the path planning relying on subjective experience of the attending doctor in the prior art, and the generated grinding path can be directly used to guide dental medical robots, dental automated grinding equipment, and the like to carry out tooth preparation, which not only reduces the tooth preparation pressure of the dentist, but also is beneficial to the clinical application and development of automated tooth preparation technology.

[0020] Further, the method for inflating the preparation body point cloud model by a distance r comprises the following steps:

[0021] calculating unit normal vectors of all minimum grid units in the preparation body point cloud model;

[0022] calculating unit normal vectors of all points in the preparation body point cloud model based on the unit normal vectors of all minimum grid units;

[0023] moving all points in the preparation body point cloud model by a distance r along the direction of the unit normal vector of the point.

[0024] Under the premise that the inflation distance is determined as r, the core difficulty of inflating the preparation body point cloud model lies in determining the inflation direction. Therefore, the unit normal vector of each point is taken as the inflation direction in the present application to ensure the consistency of the shape before and after inflation. However, some points in the preparation body point cloud model may be shared by multiple minimum grid units, and therefore the unit normal vectors of all minimum grid units in the preparation body point cloud model need to be calculated first to ensure accurate inflation of the preparation body point cloud model.

[0025] Further, the method for extracting the path reference region comprises the following steps:

[0026] projecting all points on the contour line of the inflated preparation body point cloud model by a first specified distance along the direction of the unit normal vector of the point to obtain a plurality of projected points;

[0027] determining the nearest point on the preparation body point cloud model to each projected point as a preliminary screening point;

[0028] judging the directionality of each preliminary screening point and the point on the contour line of the preparation body point cloud model corresponding to the preliminary screening point;

[0029] if the preliminary screening point is located in the positive direction of the unit normal vector of the point on the contour line of the preparation body point cloud model, retaining the point on the contour line of the preparation body point cloud model corresponding to the preliminary screening point as a tooth to be ground;

[0030] if the preliminary screening point is located in the negative direction of the unit normal vector of the point on the contour line of the preparation body point cloud model, eliminating the preliminary screening point;

[0031] Connecting all the points to be ground, a path reference area is obtained.

[0032] The present scheme clearly defines the detailed method of extracting the path reference area. The method first projects the point cloud on the expanded preparation body point cloud model outward by a first specified distance to obtain a plurality of projected points. Then, for each projected point, the nearest point on the tooth point cloud model is found, and these points are defined as preliminary screening points. It is not difficult to understand that each preliminary screening point is a point on the tooth point cloud model. After that, the directionality of each preliminary screening point and the point on the contour line of the corresponding preparation body point cloud model is judged. If the point cloud on the contour of the expanded preparation body point cloud model is defined as the original point, then this process can be understood as judging the directionality of the preliminary screening point compared to the corresponding original point. If the preliminary screening point is located in the direction of the unit normal vector of the corresponding original point, the original point is retained and defined as a point to be ground. If the preliminary screening point is located in the opposite direction of the unit normal vector of the corresponding original point, the preliminary screening point is excluded. Finally, connecting all the retained points to be ground, the path reference area is obtained.

[0033] The present scheme creatively provides a detailed method of extracting the path reference area, which provides a more reliable logic for the generation of the tooth preparation grinding path, and is conducive to the automation and coding development of the grinding path generation process. The first specified distance can be adaptively set according to the actual working condition to ensure that all the projected points are located outside the expanded preparation body point cloud model and the tooth point cloud model.

[0034] Further, the first specified distance is greater than r.

[0035] Further, the same coordinate system is a three-dimensional space coordinate system, wherein the Z-axis is parallel to the direction of the line connecting the crown to the root. The present scheme clearly defines that the Z-axis direction of the three-dimensional coordinate system extends vertically, which is convenient for subsequent division of closed-loop area and open-loop area and generation of respective grinding paths.

[0036] Further, the method of dividing the path reference area into closed-loop area and open-loop area comprises:

[0037] Extracting the edge line of the path reference area;

[0038] Passing through the lowest point on the edge line, a plane perpendicular to the Z-axis is made, which is defined as the first plane;

[0039] Moving the first plane upward along the Z-axis by a second specified distance to obtain a second plane;

[0040] Taking the path reference area below the second plane as the closed-loop area and the path reference area above the second plane as the open-loop area.

[0041] The second plane is obtained based on a second specified distance, and the second specified distance can be adaptively set according to actual working conditions, so as to ensure that the grinding path in the closed loop region can form a complete closed path.

[0042] For the edge line of the path reference region in the present solution, it can be understood that the path reference region obtained in the present application is a semi-closed region with an opening, and the edge line is the contour line connected at the beginning and end along the edge of the opening.

[0043] In addition, due to the difference in shape and structure of different teeth to be ground, the number of open loop regions may be more than one, and at this time, the grinding path of each open loop region needs to be generated respectively.

[0044] Further, the method for generating the grinding path of the closed loop region comprises:

[0045] From the lowest point to the highest point of the closed loop region, every interval third specified distance is used to intercept the closed loop region with a third plane perpendicular to the Z axis, to obtain a plurality of intersection points of the external contour of the closed loop region and the third plane, defined as first contour points;

[0046] Remove the repeated first contour points;

[0047] Process the remaining first contour points so that the distance between two adjacent first contour points is between a fourth specified distance and a fifth specified distance;

[0048] Calculate the center point coordinates of each layer of first contour points along the Z axis direction;

[0049] Calculate the polar coordinate angle of each layer of first contour points relative to the center point, and arrange all first contour points in each layer in descending order of polar coordinate angle and sequentially connect the lines to obtain the closed grinding path of each layer along the Z axis direction;

[0050] Determine the interlayer transfer path between two adjacent layers of closed grinding paths;

[0051] Add an infeed path at the starting point of the closed grinding path of the lowermost layer, and add an outfeed path at the starting point of the closed grinding path of the uppermost layer.

[0052] In the scheme, the method for processing the remaining first contour points can be realized by interpolation and rejection; that is, interpolation processing is performed on two adjacent first contour points with too large spacing to ensure the accuracy of the grinding path; and rejection processing is performed on two adjacent first contour points with too small spacing to ensure the continuity and smoothness of the grinding path. The calculation in the scheme and the subsequent steps is carried out along the Z-axis direction, and "each layer" is the division by the "third specified distance". The third plane intercepts the closed loop region at different heights once, that is, the first contour points of a layer are formed. The processing of generating the open loop region grinding path in the following is the same.

[0053] Further, the method for determining the interlayer transfer path between the closed grinding paths of adjacent two layers comprises:

[0054] respectively determining the points with the maximum polar coordinate angle relative to the center point in the first contour points of adjacent two layers;

[0055] drawing a straight line from the first contour point with the maximum polar coordinate angle in the lower layer closed grinding path to the first contour point with the maximum polar coordinate angle in the upper layer closed grinding path to obtain the interlayer transfer path between the closed grinding paths of adjacent two layers.

[0056] Since the closed grinding path of each layer is a closed curve, an interlayer transfer path needs to be set between adjacent two layers. In the scheme, the polar coordinates of all first contour points are calculated with the center point of each layer as the polar coordinate origin, and the first contour point with the maximum polar coordinate angle is found out; then the first contour points with the maximum polar coordinate angle of adjacent two layers are connected by a straight line to obtain the interlayer transfer path.

[0057] Further, the method for generating the open loop region grinding path comprises:

[0058] every interval third specified distance, a fourth plane perpendicular to the Z-axis is used to intercept the open loop region from the lowest point to the highest point of the open loop region to obtain a plurality of intersection points of the external contour of the open loop region and the fourth plane, which are defined as second contour points;

[0059] removing duplicate second contour points;

[0060] processing the remaining second contour points so that the distance between adjacent two second contour points is between a fourth specified distance and a fifth specified distance;

[0061] along the Z-axis direction, the layer positions of the second contour points are divided into odd layers and even layers from bottom to top;

[0062] sorting the second contour points and obtaining the open grinding path of each layer:

[0063] For the second profile points in the odd layers, arrange in ascending order of X coordinate values and connect in turn;

[0064] For the second profile points in the even layers, arrange in descending order of X coordinate values and connect in turn;

[0065] Determine the interlayer transfer path between the open grinding paths of the adjacent two layers;

[0066] Add the infeed path at the starting point of the open grinding path of the lowermost layer, and add the retraction path at the starting point of the open grinding path of the uppermost layer.

[0067] Further, the method for determining the interlayer transfer path between the open grinding paths of the adjacent two layers comprises:

[0068] In the adjacent two layers of open grinding paths, determine whether the open grinding path in the lower layer belongs to the odd layer or the even layer:

[0069] If it belongs to the odd layer, connect the two second profile points with the maximum X coordinate values in the adjacent two layers of open grinding paths;

[0070] If it belongs to the even layer, connect the two second profile points with the minimum X coordinate values in the adjacent two layers of open grinding paths.

[0071] Through the scheme, continuous paths can be formed between the open grinding paths of each layer in turn, and the work can be completed by one infeed.

[0072] Compared with the prior art, the present application has at least the following advantages and beneficial effects:

[0073] 1. The generation method of the tooth preparation grinding path provides a standardized and normalized grinding path generation method for tooth preparation work, and overcomes the technical problems of excessive subjectivity, large precision fluctuation, low efficiency, insufficient standardization, and easy damage to adjacent teeth or dental pulp caused by relying on the subjective experience of the attending physician to plan the path in the prior art.

[0074] 2. The generation method of the tooth preparation grinding path can be directly used to guide the tooth preparation work of dental medical robots, dental automatic grinding equipment, etc., which not only reduces the tooth preparation pressure of dental doctors, but also is beneficial to the clinical application and development of automatic tooth preparation technology.

[0075] 3. The generation method of the tooth preparation grinding path provides a detailed method for extracting the path reference area, provides a more reliable logic for the generation of the tooth preparation grinding path, and is beneficial to the automation development of the grinding path generation process.

[0076] 4. The tooth preparation grinding path generation method can significantly reduce the risk of damaging adjacent teeth or dental pulp by dividing the path reference area into closed loop areas and open loop areas.

[0077] 5. The tooth preparation grinding path generation method adopts different grinding path generation methods and interlayer transfer path generation methods for closed loop areas and open loop areas, ensuring the continuity and stability of the grinding operation. BRIEF DESCRIPTION OF DRAWINGS

[0078] The drawings described herein are used to provide further understanding of the embodiments of the present application, form a part of the present application, and do not constitute a limitation of the embodiments of the present application. In the drawings:

[0079] Figure 1 is a flowchart of the embodiments of the present application;

[0080] Figure 2 is a schematic diagram of the tooth point cloud model to be ground and the preparation body point cloud model in the embodiments of the present application;

[0081] Figure 3 is a schematic diagram of the tooth point cloud model to be ground and the preparation body point cloud model after alignment in the embodiments of the present application;

[0082] Figure 4 is a schematic diagram of the preparation body point cloud model before and after inflation in the embodiments of the present application;

[0083] Figure 5 is a process diagram of extracting the path reference area in the embodiments of the present application;

[0084] Figure 6 is a schematic diagram of the original data of the extracted path reference area in the embodiments of the present application;

[0085] Figure 7 is a schematic diagram of the processed path reference area in the embodiments of the present application;

[0086] Figure 8 is a schematic diagram of the segmented path reference area in the embodiments of the present application;

[0087] Figure 9 is a schematic diagram of the complete tooth preparation grinding path obtained in the embodiments of the present application. DETAILED DESCRIPTION

[0088] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with embodiments and drawings, the illustrative embodiments and the description thereof are only used to explain the present application, and do not limit the present application. In the description of the present application, it should be understood that the orientations or positional relationships indicated by terms such as 'front', 'back', 'left', 'right', 'up', 'down','vertical', 'horizontal', 'high', 'low', 'inner', 'outer' and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the protection scope of the present application.

[0089] Embodiment 1

[0090] As shown in a method for generating a tooth preparation grinding path, comprising the following steps: Figure 1

[0091] Step S1, obtaining a to-be-ground tooth point cloud model and a preparation body point cloud model; aligning the to-be-ground tooth point cloud model and the preparation body point cloud model in the same coordinate system. The coordinate system is a Cartesian coordinate system, preferably a three-dimensional space coordinate system, wherein the Z axis is parallel to the direction of the connecting line from the tooth crown to the tooth root.

[0092] Step S2, inflating the preparation body point cloud model by a distance r to obtain an inflated preparation body point cloud model; wherein r is the radius of a bur used for tooth preparation.

[0093] The specific method for inflating the preparation body point cloud model by a distance r includes:

[0094] S201, calculating the unit normal vector of all minimum grid elements in the preparation body point cloud model; the minimum grid element in the present embodiment is a triangular patch. For any triangular patch, its unit normal vector is calculated by the following formula:

[0095] ;

[0096] In the formula, n is the unit normal vector of the triangular patch; , is the vector of any two non-repeating edges of the triangular patch.

[0097] S202, based on the unit normal vectors of all minimum grid elements, calculating the unit normal vector of all points in the preparation body point cloud model. For any point, its unit normal vector is calculated by the following formula:

[0098] ;

[0099] ​​In the formula: is the unit normal vector of the point; represents the unit normal vector of the i-th triangular facet sharing the point, i = 1, 2, …, n; n represents the total number of triangular facets sharing the point.

[0100] S203, moving all points in the preparation point cloud model in the direction of the unit normal vector of the point by a distance r.

[0101] Step S3, based on the expanded preparation point cloud model and the to-be-ground tooth point cloud model, extracting a path reference area and denoising. Specifically, it includes:

[0102] S301, projecting all points on the contour line of the expanded preparation point cloud model by a first specified distance in the direction of the unit normal vector of the point to obtain a plurality of projected points.

[0103] In this embodiment, the first specified distance is greater than r, and is preferably 5mm.

[0104] S302, determining the nearest point on the to-be-ground tooth point cloud model to each projected point using a KD tree search algorithm, and defining it as a primary screening point.

[0105] S303, judging the directionality of each primary screening point and the point on the contour line of the corresponding preparation point cloud model:

[0106] If a primary screening point is located in the positive direction of the unit normal vector of the point on the contour line of the corresponding preparation point cloud model, the point on the contour line of the corresponding preparation point cloud model corresponding to the primary screening point is retained and defined as a to-be-ground point.

[0107] If a primary screening point is located in the negative direction of the unit normal vector of the point on the contour line of the corresponding preparation point cloud model, the primary screening point is removed.

[0108] All to-be-ground points are sequentially connected to obtain a path reference area.

[0109] S303, denoising: removing small surfaces that obviously deviate from the main body area in the path reference area, and smoothing the boundary of the path reference area.

[0110] Step S4, dividing the path reference area into closed loop areas and open loop areas by the following method:

[0111] S401, extracting the edge line of the path reference area.

[0112] S402, passing through the lowest point on the edge line, a plane perpendicular to the Z-axis is made, which is defined as the first plane.

[0113] S403, moving the first plane along the Z-axis by a second specified distance to obtain a second plane.

[0114] S404, dividing the path reference area by the second plane: taking the path reference area below the second plane as a closed-loop area, and taking the path reference area above the second plane as an open-loop area.

[0115] Step S5, generating a closed-loop area grinding path. The specific process is as follows:

[0116] S501, from the lowest point to the highest point of the closed-loop area, every interval third specified distance, the closed-loop area is intercepted by the third plane perpendicular to the Z axis, and a plurality of intersection points of the outer contour of the closed-loop area and the third plane are obtained, which are defined as first contour points.

[0117] S502, removing repeated first contour points.

[0118] S502, processing the remaining first contour points so that the distance between adjacent two first contour points is between the fourth specified distance and the fifth specified distance; the specific processing method in this embodiment is as follows:

[0119] judging the distance between adjacent first contour points, if the distance between two points is greater than the fifth specified distance, then performing the interpolation point operation through the interpolation algorithm; if the distance between two points is less than the fourth specified distance, then removing one of the points; and further ensuring that the distance between adjacent two first contour points is between the fourth specified distance and the fifth specified distance.

[0120] S503, calculating the center point coordinates (x c , y c , z c ) of each layer of first contour points along the Z axis direction:

[0121] ;

[0122] wherein: z t is the Z axis coordinate value of the third plane for interception; n p represents the total number of first contour points in the layer; x1, x2, … x np represent the X axis coordinates of each first contour point in the layer respectively; y1, y2, … y np represent the Y axis coordinates of each first contour point in the layer respectively.

[0123] S504, calculating the polar coordinate angle of each layer of first contour points relative to the center point, and arranging all first contour points in each layer in descending order of polar coordinate angle and sequentially connecting the lines to obtain a closed grinding path along the Z axis direction of each layer;

[0124] wherein, the specific calculation formula of the polar coordinate angle is as follows:

[0125] ;

[0126] Wherein: a is the polar coordinate angle; x t , y t are the X-axis coordinate and Y-axis coordinate of the first contour point respectively; x c , y c are the X-axis coordinate and Y-axis coordinate of the center point respectively.

[0127] S505, determine the interlayer transfer path between the adjacent two layers of closed grinding paths; the specific method is:

[0128] Determine the point with the maximum polar coordinate angle relative to the center point in the first contour points of the adjacent two layers respectively;

[0129] From the first contour point with the maximum polar coordinate angle in the lower layer closed grinding path, draw a straight line to connect to the first contour point with the maximum polar coordinate angle in the upper layer closed grinding path, to obtain the interlayer transfer path between the adjacent two layers of closed grinding paths.

[0130] S506, add the infeed path at the starting point of the lowest layer of closed grinding path, and add the retract path at the starting point of the uppermost layer of closed grinding path.

[0131] Step S6, generate the open loop area grinding path. The specific process is:

[0132] S601, from the lowest point to the highest point of the open loop area, every interval third specified distance, use the fourth plane perpendicular to the Z-axis to intercept the open loop area, to obtain the intersection points of the external contour of the open loop area and the fourth plane, defined as the second contour point.

[0133] S602, remove the repeated second contour points.

[0134] S603, process the remaining second contour points, so that the distance between the adjacent two second contour points is between the fourth specified distance and the fifth specified distance.

[0135] The specific processing method in this embodiment is:

[0136] Judge the distance between the adjacent second contour points, if the distance between the two points is greater than the fifth specified distance, then perform the interpolation point operation through the interpolation algorithm; if the distance between the two points is less than the fourth specified distance, then remove one of the points; and further ensure that the distance between the adjacent two second contour points is between the fourth specified distance and the fifth specified distance.

[0137] S604, along the Z-axis direction, from bottom to top, divide the layer position of each second contour point into odd layers and even layers.

[0138] S605, sort the second contour points in each layer, and connect the second contour points in each layer with straight lines based on the sorting result to obtain an open grinding path of each layer. The open grinding path of each layer is a line with both ends open. Wherein:

[0139] For the second contour points in the odd layer, arrange them in ascending order of X coordinate values and connect them in turn;

[0140] For the second contour points in the even layer, arrange them in descending order of X coordinate values and connect them in turn.

[0141] S606, determine the interlayer transfer path between the open grinding paths of the adjacent two layers; the specific method is:

[0142] In the open grinding paths of the adjacent two layers, judge whether the open grinding path in the lower layer belongs to the odd layer or the even layer:

[0143] If it belongs to the odd layer, connect the two second contour points with the maximum X coordinate values in the open grinding paths of the adjacent two layers, respectively;

[0144] If it belongs to the even layer, connect the two second contour points with the minimum X coordinate values in the open grinding paths of the adjacent two layers, respectively.

[0145] S607, add an infeed path at the starting point of the open grinding path of the lowermost layer, and add an outfeed path at the starting point of the open grinding path of the uppermost layer.

[0146] Step S7, add the open-loop area grinding path after the closed-loop area grinding path to obtain a complete tooth preparation grinding path.

[0147] In this embodiment, the third specified distance < the fourth specified distance < the second specified distance < the fifth specified distance is satisfied.

[0148] Preferably, the second specified distance = 0.2mm, the third specified distance = 0.1mm, the fourth specified distance = 0.15mm, and the fifth specified distance = 0.3mm.

[0149] The tooth preparation grinding path obtained in this embodiment can be used to control the action of a dental robot or an automatic grinding device, and can provide a smooth, high-quality and non-interfering tooth preparation grinding path for automated tooth preparation, thereby solving the problem of difficult path planning for automated tooth preparation and facilitating the application of automated tooth preparation to clinical use and reducing the tooth preparation pressure of dentists.

[0150] Embodiment 2:

[0151] A method for generating a tooth preparation grinding path, based on embodiment 1, this embodiment takes the patient's front teeth as an example to illustrate the present application.

[0152] This embodiment obtains the following through an oral scanner: Figure 2 The point cloud model of the tooth to be ground and the point cloud model of the preparatory body shown are in Figure 2 In the image, the left image shows the point cloud model of the tooth to be ground, and the right image shows the point cloud model of the preparatory body.

[0153] The two models aligned using mesh model processing software are as follows: Figure 3 As shown.

[0154] In this embodiment, the operation of the dilated pre-volume point cloud model was completed in MATLAB software. The diagrams before and after dilation are shown below. Figure 4 As shown.

[0155] Then, the path baseline region extraction operation is performed to... Figure 5 Let's take an example to illustrate:

[0156] Figure 5 The image shows points on the outline of the pre-expanded point cloud model, points C and F. The corresponding probe points are points A and D, and the initial screening points are points B and E. Among them:

[0157] The initial screening point B is located in the negative direction of the normal vector of point C on the outline of the preliminary point cloud model, so the initial screening point B is removed.

[0158] The initial screening point E is located in the positive direction of the normal vector of point F on the contour line of the preparatory body point cloud model. Therefore, the point on the contour line of the preparatory body point cloud model corresponding to the initial screening point E is retained, that is, point F is retained and point F is used as a grinding point.

[0159] The original data of the path reference area extracted in this embodiment is as follows: Figure 6 As shown, there are some small regions that are clearly detached from the main area, and their boundaries are irregularly jagged. Therefore, after denoising, the result is as follows: Figure 7 The processed path reference area is shown. Figure 7 For example, the edge line of the path reference area is... Figure 7 The edge profile of the top open end, in Figure 7 The image is indicated by a yellow line.

[0160] It should be noted that: in Figure 4 and Figure 6 In the diagram, the horizontal axis is the Y-axis, the vertical axis is the Z-axis, and the unit is mm. Figure 7 The two images on the left and right show the baseline area of ​​the path from different perspectives.

[0161] Next, the path reference region is divided into closed-loop and open-loop regions, such as... Figure 8 As shown; Figure 8The red line in the diagram represents the second plane. This embodiment, after segmentation, yields two open-loop regions (i.e.,...). Figure 8 (The upper right and middle images), the closed loop area is... Figure 8 The image is shown on the lower right side of the middle page.

[0162] Finally, the closed-loop and open-loop grinding paths are generated separately, and then merged to obtain the complete tooth preparation grinding path. This process can be referenced. Figure 9 As shown; it is not difficult to understand, Figure 9 The upper left and middle images show the grinding paths for the two open-loop regions, respectively. Figure 9 The lower left image shows the grinding path for the closed-loop region; by adding the two open-loop region grinding paths sequentially after the closed-loop region grinding path, the following can be obtained: Figure 9 The tooth preparation and grinding path is shown on the right side. Furthermore, those skilled in the art should understand that... Figure 9 The straight lines in the middle indicate the tool entry path and / or tool retraction path.

[0163] It should be noted that there are two open-loop grinding paths in this embodiment. The order of their operation is not required, as long as all open-loop grinding paths are placed after the closed-loop grinding paths. In other words, during tooth preparation, the tool moves along the closed-loop grinding path first and then along each open-loop grinding path in sequence.

[0164] Example 3:

[0165] A system for generating tooth preparation grinding paths, used to execute the generation method in Example 1, the system comprising:

[0166] Point cloud acquisition module: used to acquire the point cloud model of the tooth to be ground and the point cloud model of the preparatory body;

[0167] Point cloud processing module: used to align the point cloud model of the tooth to be ground with the point cloud model of the preparatory body in the same coordinate system;

[0168] Point cloud inflation module: used to inflate the preparatory volume point cloud model by a distance r to obtain the inflated preparatory volume point cloud model;

[0169] Path reference region extraction module: used to extract the path reference region and remove noise;

[0170] Segmentation module: used to divide the path reference region into closed-loop region and open-loop region;

[0171] First path generation module: used to generate grinding paths for closed-loop regions;

[0172] Second path generation module: used to generate grinding paths in the open-loop region;

[0173] Path merging module: Used to add the open-loop region grinding path after the closed-loop region grinding path, and output the complete tooth preparation grinding path.

[0174] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0175] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

Claims

1. A method of generating an abrading path for tooth preparation, characterized by, The method comprises the following steps: obtaining a to-be-ground tooth point cloud model and a preparation body point cloud model; aligning the to-be-ground tooth point cloud model and the preparation body point cloud model in the same coordinate system; inflating the preparation body point cloud model by a distance r to obtain an inflated preparation body point cloud model; wherein r is the radius of a tool used for tooth preparation; extracting a path reference region based on the inflated preparation body point cloud model and the to-be-ground tooth point cloud model, and denoising; dividing the path reference region into a closed loop region and an open loop region; generating a closed loop region grinding path; generating an open loop region grinding path; adding the open loop region grinding path after the closed loop region grinding path to obtain a tooth preparation grinding path.

2. The method of claim 1, wherein, The method for inflating the preparation body point cloud model by a distance r comprises: calculating the unit normal vector of all minimum grid units in the preparation body point cloud model; calculating the unit normal vector of all points in the preparation body point cloud model based on the unit normal vector of all minimum grid units; moving all points in the preparation body point cloud model in the direction of their own unit normal vector by a distance r.

3. The method of claim 1, wherein, The method for extracting the path reference region comprises: projecting all points on the contour line of the inflated preparation body point cloud model by a first specified distance in the direction of their own unit normal vector to obtain a plurality of projected points; determining the point on the to-be-ground tooth point cloud model closest to each projected point as a preliminary screening point; judging the directionality of each preliminary screening point and the point on the contour line of the preparation body point cloud model corresponding to the preliminary screening point; if the preliminary screening point is located in the positive direction of the unit normal vector of the point on the contour line of the preparation body point cloud model, retaining the point on the contour line of the preparation body point cloud model corresponding to the preliminary screening point as a to-be-ground point; if the preliminary screening point is located in the negative direction of the unit normal vector of the point on the contour line of the preparation body point cloud model, eliminating the preliminary screening point; connecting all to-be-ground points to obtain a path reference region.

4. The method of claim 3, wherein, The first specified distance is greater than r.

5. The method of claim 1, wherein, The same coordinate system is a three-dimensional space coordinate system, wherein the Z-axis is parallel to the direction of the line connecting the crown to the root.

6. The method of claim 5, wherein, The method for dividing the path reference region into a closed loop region and an open loop region comprises: extracting the edge line of the path reference region; drawing a plane perpendicular to the Z-axis through the lowest point on the edge line, and defining the plane as a first plane; moving the first plane upward along the Z-axis by a second specified distance to obtain a second plane; taking the path reference region below the second plane as the closed loop region and taking the path reference region above the second plane as the open loop region.

7. The method of claim 5, wherein, The method for generating a closed loop region grinding path comprises: from the lowest point to the highest point of the closed loop region, every interval of a third specified distance is used to intercept the closed loop region with a third plane perpendicular to the Z-axis to obtain a plurality of intersection points between the outer contour of the closed loop region and the third plane, and the intersection points are defined as first contour points; removing duplicate first contour points; processing the remaining first contour points so that the distance between adjacent two first contour points is between a fourth specified distance and a fifth specified distance; calculating the center point coordinates of each layer of first contour points in the direction of the Z-axis; Calculate the polar coordinate angle of each first contour point relative to the center point of the layer, and arrange all first contour points in each layer in descending order of polar coordinate angle and sequentially connect them to obtain a closed grinding path in each layer along the Z-axis direction; Determine the interlayer transfer path between the closed grinding paths of adjacent two layers; Add an infeed path at the starting point of the closed grinding path of the lowermost layer, and add an outfeed path at the starting point of the closed grinding path of the uppermost layer.

8. The method of claim 7, wherein, The method for determining the interlayer transfer path between the closed grinding paths of adjacent two layers comprises: Determine the first contour point with the maximum polar coordinate angle relative to the center point in the first contour points of adjacent two layers, respectively; Draw a straight line from the first contour point with the maximum polar coordinate angle in the closed grinding path of the lower layer to the first contour point with the maximum polar coordinate angle in the closed grinding path of the upper layer to obtain the interlayer transfer path between the closed grinding paths of adjacent two layers.

9. The method of claim 5, wherein, The method for generating the open-loop region grinding path comprises: From the lowest point to the highest point of the open-loop region, every third specified distance is intercepted by a fourth plane perpendicular to the Z-axis to obtain a plurality of intersection points between the outer contour of the open-loop region and the fourth plane, which are defined as second contour points; Remove duplicate second contour points; Process the remaining second contour points so that the distance between adjacent two second contour points is between the fourth specified distance and the fifth specified distance; In the Z-axis direction, divide the layer position of each second contour point into odd layers and even layers from bottom to top; Sort the second contour points and obtain the open grinding path of each layer: For the second contour points in the odd layers, arrange them in ascending order of X coordinate values and sequentially connect them; For the second contour points in the even layers, arrange them in descending order of X coordinate values and sequentially connect them; Determine the interlayer transfer path between the open grinding paths of adjacent two layers; Add an infeed path at the starting point of the open grinding path of the lowermost layer, and add an outfeed path at the starting point of the open grinding path of the uppermost layer.

10. The method of claim 9, wherein, The method for determining the interlayer transfer path between the open grinding paths of adjacent two layers comprises: In the open grinding paths of adjacent two layers, determine whether the open grinding path on the lower side belongs to the odd layers or the even layers: If it belongs to the odd layers, connect the two second contour points with the maximum X coordinate values in the open grinding paths of adjacent two layers; If it belongs to the even layers, connect the two second contour points with the minimum X coordinate values in the open grinding paths of adjacent two layers.

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