Dental implantation positioning guide plate deviation analysis method based on digital simulation

Abstract

The invention relates to the technical field of tooth implantation tools, in particular to a tooth implantation positioning guide plate deviation analysis method based on digital simulation, and the method comprises the following steps: obtaining a guide plate scanning model, an oral cavity STL model and an alveolar bone model of a patient to be detected; determining an oral cavity contact error factor corresponding to each guide plate triangular patch, and screening out a contact triangular patch; according to the distance and direction deviation condition between the contact triangular patch and the alveolar bone model and the oral cavity contact error factor corresponding to the contact triangular patch, determining target supporting strength corresponding to the contact triangular patch; acquiring a guide hole axis and a guide plate fitting error; the local supporting degree of the contact triangular patch in the preset direction is determined; and determining the target guide plate deviation according to the guide plate fitting error and all local support degrees. The guide plate deviation is quantified relatively objectively by combining the guide plate fitting error and the supporting conditions of the guide plate in different areas, so that the reasonability of guide plate deviation analysis is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dental implant tools, and particularly relates to a dental implant positioning guide plate deviation analysis method based on digital simulation. BACKGROUND

[0002] With the continuous development of digital dentistry technology, dental implant surgery gradually introduces three-dimensional scanning, CBCT (Cone Beam Computed Tomography) scanning imaging, and 3D printing and other digital methods, and by means of designing personalized patient dental implant guides, preoperative plan design can be assisted to achieve. The implant guide plate is a key guarantee for positioning accuracy in surgery, and the structure design and fitting stability of the implant guide plate will directly affect the accuracy of the implant position and the safety of the surgery. In order to improve the controllability and success rate of the implant surgery, the deviation analysis of the digital guide plate is crucial.

[0003] The dental implant guide plate is usually designed according to the patient's dental cone beam CBCT data and intraoral scanning model. The purpose of the guide plate is to fix the guide hole of the region to be implanted to assist the doctor in the operation of the dental implant, including drilling, etc., so whether the guide plate is accurately fitted with the patient's oral structure is the basis for ensuring the accuracy of the dental implant. Therefore, at present, when the deviation of the dental implant positioning guide plate is analyzed, the method usually adopted is to determine whether the guide plate deviation is fitted by scanning the model and the designed guide plate model, at this time, the guide plate deviation is represented by the guide plate fitting error.

[0004] However, in actual clinical application, the support strength of the guide plate often differs in different regions, for example, the support effect of the guide plate in different bone density tissues and mucosa is often different, such as in soft tissue or edentulous area, the support strength is often weak, and the local deformation or warping of the guide plate is more likely to occur, thereby affecting the rationality of the guide hole. As can be seen, the guide plate deviation is not only affected by the fitting condition, but also affected by the support strength. Therefore, if only the fitting of the scanned model and the designed guide plate model is considered when analyzing the guide plate deviation, the rationality of the guide plate deviation analysis may be poor due to the single consideration factor. SUMMARY

[0005] In order to solve the technical problem that the rationality of the guide plate deviation analysis is poor, the present application provides a dental implant positioning guide plate deviation analysis method based on digital simulation.

[0006] In a first aspect, the present application provides a dental implant positioning guide plate deviation analysis method based on digital simulation, which comprises:

[0007] obtain a guide plate scan model, an oral cavity STL model and an alveolar bone model of a patient to be detected, and determine each triangular facet of the guide plate scan model as a guide plate triangular facet, wherein the guide plate scan model is registered with the oral cavity STL model and the alveolar bone model respectively;

[0008] According to the distance deviation between each guide plate triangular facet and the oral cavity STL model, determine the corresponding oral cavity contact error factor of each guide plate triangular facet, and based on the oral cavity contact error factor, screen out contact triangular facets from all guide plate triangular facets;

[0009] According to the distance and direction deviation between each contact triangular facet and the alveolar bone model, and the corresponding oral cavity contact error factor of each contact triangular facet, determine the corresponding target support strength of each contact triangular facet;

[0010] Obtain the guide hole axis and the guide plate fitting error, and set a preset number of preset directions according to the plane perpendicular to the guide hole axis;

[0011] According to the projection of the target support strength of each contact triangular facet in each preset direction, determine the local support degree of each contact triangular facet in each preset direction;

[0012] According to the guide plate fitting error and the local support degree of all contact triangular facets in all preset directions, determine the target guide plate deviation.

[0013] In combination with the above first aspect, in a possible implementation manner, the determination of the corresponding oral cavity contact error factor of each guide plate triangular facet according to the distance deviation between each guide plate triangular facet and the oral cavity STL model comprises:

[0014] The nearest point error between each guide plate triangular facet and the oral cavity STL model is determined as the corresponding oral cavity contact error factor of each guide plate triangular facet.

[0015] In combination with the above first aspect, in a possible implementation manner, the screening of the contact triangular facets from all guide plate triangular facets based on the oral cavity contact error factor comprises:

[0016] According to the difference between the corresponding oral cavity contact error factors of each two guide plate triangular facets, and the minimum distance between each two guide plate triangular facets, determine the target distance metric between each two guide plate triangular facets;

[0017] According to the target distance metric between different guide plate triangular facets, cluster all guide plate triangular facets to obtain a target cluster;

[0018] The mean of the oral contact error factors corresponding to all guide plate triangular facets in each target cluster is determined as the oral contact representative error corresponding to each target cluster;

[0019] Each guide plate triangular facet in the target cluster corresponding to the minimum oral contact representative error is determined as a contact triangular facet.

[0020] In combination with the first aspect, in a possible implementation manner, the target support strength corresponding to each contact triangular facet is determined according to the distance and directional deviation between each contact triangular facet and the alveolar bone model, and the oral contact error factor corresponding to each contact triangular facet, and includes:

[0021] The nearest point error between each contact triangular facet and the alveolar bone model is determined as the dental contact error factor corresponding to each contact triangular facet;

[0022] The triangular facet closest to the contact triangular facet is selected from all triangular facets of the alveolar bone model as the reference triangular facet corresponding to the contact triangular facet;

[0023] The target support strength corresponding to each contact triangular facet is determined according to the included angle between the normal direction of each contact triangular facet and the reference triangular facet corresponding to the contact triangular facet, and the dental contact error factor and the oral contact error factor corresponding to each contact triangular facet.

[0024] In combination with the first aspect, in a possible implementation manner, the guide hole axis and the guide plate fitting error are obtained, and the method includes:

[0025] The circular edge detection algorithm is used to extract at least three horizontal section centers of gravity from the inner wall of the guide hole of the guide plate scan model, and linear fitting is performed on all the extracted centers of gravity to obtain the guide hole axis;

[0026] The region planned for implantation in the alveolar bone model is determined as a target region, and bone surface contour points are extracted from the target region;

[0027] The alveolar bone axis is constructed according to the extracted bone surface contour points;

[0028] The minimum distance between the guide hole axis and the alveolar bone axis is determined as the guide plate fitting error.

[0029] In combination with the first aspect, in a possible implementation manner, the preset number of preset directions are set according to the plane perpendicular to the guide hole axis, and the method includes:

[0030] The plane perpendicular to the guide hole axis is determined as a target plane;

[0031] Taking an arbitrary point on the target plane as a target vertex, a target number of rays in different extension directions are made from the target vertex, and the rays are recorded as target rays, where the target number is equal to half of the preset number;

[0032] The extension direction of each target ray and the opposite direction thereof are determined as preset directions.

[0033] In combination with the first aspect, in a possible implementation manner, the determining, according to the projection of the target support strength corresponding to each contact triangular facet in each preset direction, of the local support degree of each contact triangular facet in each preset direction, includes:

[0034] An angle between the direction of the normal of each contact triangular facet and each preset direction is determined as a target angle between each contact triangular facet and each preset direction;

[0035] A cosine value of the target angle between each contact triangular facet and each preset direction is determined as a target cosine between each contact triangular facet and each preset direction;

[0036] An absolute value of a product of the target support strength corresponding to each contact triangular facet and the target cosine between the target support strength and each preset direction is determined as the local support degree of each contact triangular facet in each preset direction.

[0037] In combination with the first aspect, in a possible implementation manner, the determining of the target guide plate deviation according to the guide plate fitting error and the local support degrees of all contact triangular facets in all preset directions includes:

[0038] Each two preset directions opposite to each other constitute a preset direction group;

[0039] According to a difference between the local support degrees of each contact triangular facet in two preset directions in each preset direction group and a minimum distance between each contact triangular facet and the guide hole axis, a local difference factor of each contact triangular facet in each preset direction group is determined;

[0040] According to the local difference factors of all contact triangular facets in a same preset direction group, a local guide hole risk factor in the preset direction group is determined;

[0041] A maximum value in the local guide hole risk factors in all preset direction groups is normalized to obtain a target guide hole risk factor;

[0042] The target guide hole risk factor and the guide plate fitting error are used to determine the target guide plate deviation.

[0043] In a possible implementation manner of the first aspect, the local drilling risk factor in the preset direction group is determined according to local difference factors of all the contact triangular facets in the same preset direction group.

[0044] The accumulated value of the local difference factors of all the contact triangular facets in the same preset direction group is determined as the local drilling risk factor in the preset direction group.

[0045] In a possible implementation manner of the first aspect, the target guide plate deviation is determined according to the target drilling risk factor and the guide plate fitting error.

[0046] The sum of the constant 1 and the target drilling risk factor is determined as a target correction factor.

[0047] The product of the target correction factor and the guide plate fitting error is determined as the target guide plate deviation.

[0048] In a possible implementation manner of the first aspect, the target guide plate deviation is determined according to the target drilling risk factor and the guide plate fitting error.

[0049] The guide plate scanning model, the oral cavity STL model and the alveolar bone model of the patient to be detected are obtained, and each triangular facet of the guide plate scanning model is determined as a guide plate triangular facet.

[0050] The oral cavity contact error factor corresponding to each guide plate triangular facet is determined according to the distance deviation between each guide plate triangular facet and the oral cavity STL model, and the contact triangular facet is selected from all the guide plate triangular facets based on the oral cavity contact error factor.

[0051] The target support strength corresponding to each contact triangular facet is determined according to the distance and direction deviation between each contact triangular facet and the alveolar bone model and the oral cavity contact error factor corresponding to each contact triangular facet.

[0052] The guide hole axis and the guide plate fitting error are obtained, and a preset number of preset directions are set according to the plane perpendicular to the guide hole axis.

[0053] The local support degree of each contact triangular facet in each preset direction is determined according to the projection of the target support strength corresponding to each contact triangular facet in each preset direction.

[0054] The target guide plate deviation is determined according to the guide plate fitting error and the local support degree of all the contact triangular facets in all the preset directions.

[0055] In a third aspect, a server is provided, comprising a memory and a processor. The memory is configured to store executable program code, and the processor is configured to invoke and run the executable program code from the memory, so that the device executes the method in the first aspect or any possible implementation manner of the first aspect.

[0056] In a fourth aspect, a computer program product is provided, comprising computer program code, which, when running on a computer, causes the computer to execute the method in the first aspect or any possible implementation manner of the first aspect.

[0057] In a fifth aspect, a computer-readable storage medium is provided, which stores computer program code, which, when running on a computer, causes the computer to execute the method in the first aspect or any possible implementation manner of the first aspect.

[0058] The present application has the following beneficial effects:

[0059] The digital simulation-based dental implant positioning guide plate deviation analysis method provided by the present application quantifies the guide plate deviation relatively objectively by combining the guide plate fitting error and the support condition of the guide plate in different regions, solves the technical problem of poor rationality of guide plate deviation analysis, and improves the rationality of guide plate deviation analysis. Specifically, in the guide plate deviation analysis, in addition to considering the guide plate fitting error, the present application also considers a plurality of factors related to the guide plate support condition, such as the distance deviation condition between the guide plate triangular facet and the oral cavity STL model, the distance and direction deviation condition between the contact triangular facet and the alveolar bone model, thereby quantifying the target support strength corresponding to the contact triangular facet, quantifying the local support degree of each contact triangular facet in each preset direction, and finally combining the guide plate fitting error and all local support degrees to quantify the target guide plate deviation relatively objectively, thereby improving the rationality of guide plate deviation analysis. BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art and the advantages thereof, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0061] Figure 1 A flowchart of a digital simulation-based dental implant positioning guide plate deviation analysis method of the present application;

[0062] Figure 2A component structure schematic diagram of a dental implant positioning guide plate deviation analysis system based on digital simulation according to the present application is shown in the figure.

[0063] Figure 3 A structure schematic diagram of a computer device according to the present application is shown in the figure. DETAILED DESCRIPTION

[0064] In order to further illustrate the technical means and effects taken by the present application to achieve the predetermined purposes, the specific implementation, structure, features and effects of the technical solutions proposed according to the present application are described in detail below in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0065] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0066] Reference Figure 1 The figure shows the flow of some embodiments of a dental implant positioning guide plate deviation analysis method based on digital simulation according to the present application. The dental implant positioning guide plate deviation analysis method based on digital simulation includes the following steps:

[0067] Step S1, obtain the guide plate scanning model, oral cavity STL model and alveolar bone model of the patient to be detected, and determine each triangular facet of the guide plate scanning model as a guide plate triangular facet.

[0068] The patient to be detected can be a patient to be implanted with a tooth. The guide plate scanning model can be a three-dimensional model of the guide plate, and the method for obtaining the guide plate scanning model can be: scanning and reconstructing the physical guide plate obtained by 3D printing by using a desktop high-precision structured light scanner, obtaining a real three-dimensional surface model of the guide plate, and displaying the three-dimensional surface model in a three-dimensional STL (Stereolithography File) format. The three-dimensional STL model obtained at this time is the guide plate scanning model. The oral STL model can be a three-dimensional model including tooth surfaces, gum soft tissues, and mucosa regions, and the method for obtaining the oral STL model can be: scanning the oral cavity of the patient to be detected by using CBCT (Cone Beam Computed Tomography), and displaying the three-dimensional model obtained at this time in a three-dimensional STL format. The three-dimensional STL model obtained at this time is the oral STL model. The alveolar bone model can be a reconstructed three-dimensional hard tissue model including tooth structures and alveolar bone contours in the oral cavity, and the method for obtaining the alveolar bone model can be: scanning the teeth and alveolar bone in the oral cavity of the patient to be detected by using CBCT, and displaying the three-dimensional model obtained at this time in a three-dimensional STL format. The three-dimensional STL model obtained at this time is the alveolar bone model.

[0069] The guide plate scanning model is registered with the oral STL model. The guide plate scanning model is registered with the alveolar bone model. Different three-dimensional models can be registered by using an ICP (Iterative Closest Point) algorithm. The three-dimensional STL model is a commonly used three-dimensional model, and the essence thereof is to describe the geometric shape of the surface of an object by using a set of triangular meshes. That is, when an STL file format stores a model, the surface of the model is divided into a plurality of triangular meshes, and the three vertex coordinates and the triangular normal vector components of each triangular mesh are marked to determine the positive direction of each triangular mesh.

[0070] It should be noted that first, preoperative oral structure data and a physical scanning model of the postoperative guide plate can be obtained. The preoperative data mainly includes CBCT (Cone Beam Computed Tomography) scanning of the patient and the results of intraoral three-dimensional surface scanning. The CBCT data can provide high-precision volume information, and can clearly show the alveolar bone structure, the tooth root direction, and the nerve canal distribution. The intraoral scanning can obtain a three-dimensional model of the tooth surface, the gum soft tissue, and the mucosa region, so as to perform subsequent guide plate design and analysis of the fitting error.

[0071] According to the results of cone beam CT (CBCT) scanning, a three-dimensional hard tissue model of the patient's oral cavity can be reconstructed, mainly including tooth structure and alveolar bone profile. Since CBCT has high accuracy in hard tissue imaging, it can be used as an important reference for analyzing the fitting area of the guide plate. After registering the guide plate scanning model with the CBCT reconstruction model, the contact area between the inner surface of the guide plate and the tooth body can be identified.

[0072] Secondly, after completing the preoperative planning, the doctor or technician uses digital implant software (such as Simplant) to design a personalized guide plate based on the registration results of the oral scanning model and CBCT. The guide plate design involves the fitting support area of the tooth or mucosa, the position and direction of the guide hole, and then exports it as a three-dimensional STL file.

[0073] Next, with the help of high-precision 3D printing equipment, the guide plate is printed into a solid object. After printing, to evaluate the actual deformation and manufacturing precision of the guide plate, the solid guide plate is scanned and reconstructed. With the help of a desktop high-precision structured light scanner, the real three-dimensional surface model of the guide plate is obtained. Based on the obtained guide plate model, it serves as the basic data source for subsequent error analysis, support stability, and guide hole direction evaluation.

[0074] To evaluate the fitting accuracy of the guide plate in the preoperative model, it is often necessary to locally register the guide plate scanning model with the preoperative oral scanning model. The registration algorithm can be ICP matching.

[0075] Step S2, according to the distance deviation between each guide plate triangular facet and the oral cavity STL model, determine the corresponding oral contact error factor of each guide plate triangular facet, and based on the oral contact error factor, screen out the contact triangular facet from all guide plate triangular facets.

[0076] As an example, this step can include the following steps:

[0077] First, determine the nearest point error between each guide plate triangular facet and the oral cavity STL model as the corresponding oral contact error factor of each guide plate triangular facet.

[0078] Wherein, the oral contact error factors corresponding to different guide plate triangular facets can represent the distance deviation between different positions on the guide plate fitting surface and the oral cavity surface.

[0079] It should be noted that since multiple triangular facets on the surface of the guide plate do not contact the oral cavity structure, subsequent triangular facets are distinguished by different oral contact error factors.

[0080] Second, according to the difference between the oral contact error factors corresponding to each two guide plate triangular facets, and the minimum distance between each two guide plate triangular facets, determine the target distance metric between each two guide plate triangular facets.

[0081] For example, the formula corresponding to the target distance metric between different guide plate triangular facets can be:

[0082] D ij = norm(d ij ) + norm(|A i -A j |);

[0083] where D ij is the target distance metric between the ith guide plate triangular facet and the jth guide plate triangular facet. i and j are the serial numbers of different guide plate triangular facets. norm() is a normalization function. d ij is the minimum distance between the ith guide plate triangular facet and the jth guide plate triangular facet. || is an absolute value function. A i is the oral contact error factor corresponding to the ith guide plate triangular facet. A j is the oral contact error factor corresponding to the jth guide plate triangular facet.

[0084] It should be noted that when D ij is smaller, it often means that the distance between the ith guide plate triangular facet and the jth guide plate triangular facet is closer, and the oral contact errors corresponding to the ith guide plate triangular facet and the jth guide plate triangular facet are closer; it often means that the ith guide plate triangular facet and the jth guide plate triangular facet can be divided into the same cluster.

[0085] Thirdly, according to the target distance metric between different guide plate triangular facets, all guide plate triangular facets are clustered to obtain target clusters.

[0086] For example, according to the target distance metric between different guide plate triangular facets, all guide plate triangular facets can be clustered by DBSCAN (Density-Based Spatial Clustering of Applications with Noise) algorithm, and the obtained clustering cluster is recorded as the target cluster.

[0087] Fourthly, the mean value of the oral contact error factors corresponding to all guide plate triangular facets in each target cluster is determined as the oral contact representative error corresponding to each target cluster.

[0088] Fifthly, each guide plate triangular facet in the target cluster corresponding to the minimum oral contact representative error is determined as the contact triangular facet.

[0089] It should be noted that the smaller the oral cavity contact error corresponding to the target cluster, the more likely the guide plate triangular facet in the target cluster represents the contact surface between the guide plate and the oral structure. And the smaller the oral cavity contact error factor corresponding to the contact triangular facet, the better the support effect of the contact triangular facet in the normal direction thereof.

[0090] Step S3, determining the target support strength corresponding to each contact triangular facet according to the distance and directional deviation between each contact triangular facet and the alveolar bone model, and the oral cavity contact error factor corresponding to each contact triangular facet.

[0091] It should be noted that when the actual guide plate is in contact with the inner surface of the oral cavity, for the multiple surfaces of the guide plate that have a support effect, for the area that fits the teeth, since the hard tissue support condition of the residual teeth during implantation is relatively good, the deformation of the guide plate in the corresponding area is small, that is, the support strength of the area where the small triangular facet is located is high. And for the area where the guide plate contacts the soft tissue, such as the edentulous area and the area where the mill is located, even if the fitting degree is good, the support is weak and easy to deform. Therefore, considering the fitting effect of the guide plate with different areas, the support strength of different triangular facets can be calculated.

[0092] As an example, the present step can include the following steps:

[0093] Firstly, the nearest point error between each contact triangular facet and the alveolar bone model is determined as the tooth contact error factor corresponding to each contact triangular facet.

[0094] It should be noted that the larger the tooth contact error factor, the more likely the corresponding guide plate position does not have direct contact with the hard part such as teeth.

[0095] Secondly, the triangular facet closest to the contact triangular facet is selected from all the triangular facets of the alveolar bone model as the reference triangular facet corresponding to the contact triangular facet.

[0096] Thirdly, the target support strength corresponding to each contact triangular facet is determined according to the included angle between the normal direction of each contact triangular facet and the normal direction of the reference triangular facet corresponding thereto, and the tooth contact error factor and the oral cavity contact error factor corresponding to each contact triangular facet.

[0097] Wherein, the normal is a unit vector perpendicular to the triangular facet. The normal direction is usually determined by the arrangement order of the vertices (right-hand rule). The included angle between the normal directions of different triangular facets can be in the range of [0°, 180°].

[0098] For example, the formula for determining the target support strength corresponding to the contact triangular facet can be:

[0099]

[0100] wherein R a is the target support strength corresponding to the a-th contact triangle facet. a is the serial number of the contact triangle facet. norm() is the normalization function. B a is the tooth contact error factor corresponding to the a-th contact triangle facet. A a is the oral cavity contact representative error corresponding to the a-th contact triangle facet. cos() is the cosine function. θ a is the included angle between the direction of the normal of the a-th contact triangle facet and the direction of the normal of the reference triangle facet corresponding to the a-th contact triangle facet. The normal of a triangle facet is a directed vector, and the direction is often determined by the vertex order (right-hand rule). The included angle between the normal directions of different triangle facets often ranges from 0° to 180°.

[0101] It should be noted that norm(-B a ) can represent the correction amount of the support strength, and when B a is larger, the support strength of the corresponding triangle facet tissue position is relatively smaller. 1-cos(θ a ) can represent the fit degree of the guide plate and the inner contact area of the oral cavity, and when θ a is larger, that is, θ a tends to 180°, at this time, the outer surfaces of the two surfaces are relatively parallel, and higher fit often corresponds to better support strength. A a can represent the distance deviation of the corresponding guide plate position and the oral cavity surface, and the smaller the value, the better the fit degree of the corresponding guide plate position and the oral cavity surface. Therefore, when R a is larger, it often indicates that the a-th contact triangle facet corresponds to better support strength.

[0102] Step S4, obtaining the guide hole axis and the guide plate fit error, and setting a preset number of preset directions according to the plane perpendicular to the guide hole axis.

[0103] wherein the preset number can be a preset number, which can be 8.

[0104] It should be noted that after the local modeling of the guide plate support strength is completed, the fit accuracy between the guide hole direction and the alveolar bone axis can be further analyzed. This accuracy is directly related to the bone entry direction, initial stability, and the ability to avoid important anatomical structures (such as nerve canal, maxillary sinus) during the in- operation implantation of the implant. Therefore, whether the guide hole axis is consistent with the bone axis of the target alveolar bone region is a key indicator for evaluating the safety and effectiveness of the guide plate, so it is crucial to quantify the guide plate fit error.

[0105] As an example, the present step can include the following steps:

[0106] Firstly, using a circular edge detection algorithm, the center of at least three horizontal sections of the inner wall of the guide hole of the guide plate scanning model is extracted, and a straight line fitting is performed on all the extracted centers to obtain the guide hole axis.

[0107] The guide hole axis, also known as the guide hole center axis straight line, represents the direction of the center axis of the guide hole. The circular edge detection algorithm can be Hough circle transformation or contour fitting.

[0108] It should be noted that in the guide plate scanning model, the guide hole region is usually a hollow cylindrical structure. By intercepting multiple horizontal sections of the inner wall of the guide hole, the center coordinates of each layer can be extracted using a circular edge detection algorithm. Fitting these centers to a straight line can represent the direction of the center axis of the guide hole, and the guide hole center axis straight line, also known as the guide hole axis, is obtained.

[0109] Secondly, the region planned for implantation in the above alveolar bone model is determined as the target region, and the bone surface contour points are extracted from the target region.

[0110] The bone surface contour points can be alveolar bone contour points, which can be obtained by neural network or threshold segmentation. The target region is the region where the patient needs to implant a tooth.

[0111] Thirdly, the alveolar bone axis is constructed according to the extracted bone surface contour points.

[0112] For example, the method of constructing the alveolar bone axis can be: based on the extracted bone surface contour points, the local principal axis direction can be fitted using principal component analysis (PCA), or the axial direction can be extracted using a spline curve on the crest surface, to represent the natural growth direction of the alveolar bone, thereby obtaining the alveolar bone axis.

[0113] Fourthly, the minimum distance between the above guide hole axis and the above alveolar bone axis is determined as the guide plate fitting error.

[0114] It should be noted that the guide plate fitting error can represent the fitting error between the guide plate and the bone axis of the alveolar bone region. In the above analysis of the fitting error, the fitting degree between the guide plate and the oral model is quantified as a distance error, and the stability between the guide plate and the implantation area is preliminarily judged by this method. When the fitting error is relatively small, it means that the guide plate can be well fitted with the tooth or gum surface in this region, which helps to improve the positioning accuracy and operational safety.

[0115] Fifthly, the plane perpendicular to the above guide hole axis is determined as the target plane.

[0116] Step 6, taking any point on the target plane as a target vertex, and making target number of rays in different directions from the target vertex, denoted as target rays.

[0117] The target number can be equal to half of the preset number.

[0118] For example, if the preset number is 8, the target number is 4, and from the target vertex, a ray in the direction of 0°, a ray in the direction of 45°, a ray in the direction of 90°, and a ray in the direction of 135° can be made, and these four rays are collectively referred to as target rays.

[0119] Step 7, determining the extension direction of each target ray and its opposite direction as a preset direction.

[0120] The direction opposite to the direction of 0° can be the direction of 180°; the direction opposite to the direction of 45° can be the direction of 225°; the direction opposite to the direction of 90° can be the direction of 270°; and the direction opposite to the direction of 135° can be the direction of 315°.

[0121] Step S5, determining the local support degree of each contact triangular facet in each preset direction according to the projection of the target support strength corresponding to each contact triangular facet in each preset direction.

[0122] It should be noted that in the traditional design of the guide plate, since the guide plate is generally taken as the main fitting reference point of the tooth surface or the mucosa surface, if the support strength of some areas is not enough, it may cause the guide plate to move slightly or warp during the operation, so that the actual direction of the guide hole deviates from the preoperative planning direction. Small fitting error does not mean that the support effect of this area is good. During the guide hole operation, the doctor may apply pressure at multiple inclined angles of the guide hole axial direction, such as implant insertion, drilling adjustment, etc. If the support strength in these non-axial directions is insufficient, even if the fitting error is very small, it may also cause the guide plate to deform or locally warp, resulting in actual deviation of the guide hole direction, affecting the reliability of subsequent operations.

[0123] Therefore, in the risk assessment of the guide hole direction, the support strength in multiple directions perpendicular to the guide hole axial direction can be combined to quantify the risk of the guide hole. When the support strength in multiple directions is large, the stability of the corresponding guide hole is usually good, otherwise, deviation in a certain direction may occur during the operation, resulting in an increase in the fitting error.

[0124] As an example, the present step can include the following steps:

[0125] Firstly, an included angle between a normal direction of each contact triangular facet and each preset direction is determined as a target included angle between each contact triangular facet and each preset direction.

[0126] The target included angle can be in a range of [0°, 180°].

[0127] Secondly, a cosine value of the target included angle between each contact triangular facet and each preset direction is determined as a target cosine between each contact triangular facet and each preset direction.

[0128] Thirdly, an absolute value of a product of the target support strength corresponding to each contact triangular facet and the target cosine between the contact triangular facet and each preset direction is determined as a local support degree of each contact triangular facet in each preset direction.

[0129] For example, a formula for determining the local support degree of the contact triangular facet in the preset direction can be:

[0130] G ab = |R a × cos(θ ab )|;

[0131] wherein G ab is the local support degree of the a-th contact triangular facet in the b-th preset direction. a is a serial number of the contact triangular facet. b is a serial number of the preset direction. || is an absolute value function. R a is the target support strength corresponding to the a-th contact triangular facet. cos() is a cosine function. θ ab is the target included angle between the a-th contact triangular facet and the b-th preset direction, that is, an included angle between a normal direction of the a-th contact triangular facet and the b-th preset direction. cos(θ ab ) is the target cosine between the a-th contact triangular facet and the b-th preset direction.

[0132] It should be noted that G ab can represent a support condition of the a-th contact triangular facet in the b-th preset direction.

[0133] Step S6, determining a target guide deviation according to the guide fitting error and the local support degrees of all contact triangular facets in all preset directions.

[0134] As an example, this step can include the following steps:

[0135] Firstly, each two preset directions opposite to each other form a preset direction group.

[0136] For example, if there are a total of 8 preset directions, and these 8 preset directions are 0°, 45°, 90°, 135°, 180°, 225°, 270° and 315°, then 4 preset direction groups can be formed, and these 4 preset direction groups can be {0°, 180°}, {45°, 225°}, {90°, 270°} and {135°, 315°} respectively.

[0137] The second step is to determine the local difference factor of each contact triangular facet in each preset direction group based on the difference between the local support levels of each contact triangular facet in two preset directions in each preset direction group, and the minimum distance between each contact triangular facet and the aforementioned guide hole axis.

[0138] For example, the formula for determining the local difference factor of a contact triangular facet under a preset orientation group can be:

[0139]

[0140] Among them, S a,t Q is the local difference factor of the a-th contact triangular facet in the t-th preset orientation group. a is the index of the contact triangular facet. t is the index of the preset orientation group. a It is the minimum distance between the a-th contact triangular facet and the guide hole axis. γ is a pre-set factor greater than 0, mainly used to prevent the denominator from being 0; it can be 0.0001. || is the absolute value function. G a,t,1 G represents the degree of local support of the a-th contact triangular facet in the first preset direction of the t-th preset direction group. a,t,2 It represents the degree of local support of the a-th contact triangular facet in the second preset direction of the t-th preset direction group.

[0141] It should be noted that, Can be used as |G a,t,1 -G a,t,2 | weight. When |G a,t,1 -G a,t,2 A larger | value often indicates different levels of support in opposite directions, suggesting a greater likelihood of deviation and thus increased fitting error. Therefore, when S a,t The larger the value, the more likely the a-th contact triangular facet is to deviate in the t-th preset direction group, thus leading to an increase in the bonding error.

[0142] The third step is to determine the local guide hole risk factor under the preset direction group based on the local difference factor of all contact triangular facets under the same preset direction group.

[0143] For example, the accumulated value of the local difference factors of all the contact triangular facets under the same preset direction group can be determined as the local pilot hole risk factor under the preset direction group.

[0144] For example, the formula corresponding to the local pilot hole risk factor under the preset direction group can be:

[0145]

[0146] wherein, S t is the local pilot hole risk factor under the tth preset direction group. t is the serial number of the preset direction group. a is the serial number of the contact triangular facet. N is the number of the contact triangular facets. S a,t is the local difference factor of the ath contact triangular facet under the tth preset direction group.

[0147] It should be noted that, the larger S a,t is, the more likely the deviation of the ath contact triangular facet under the tth preset direction group occurs, thereby leading to the increase of the fitting error. Therefore, the larger S t is, the more likely the deviation of different contact triangular facets under the tth preset direction group occurs, thereby leading to the increase of the fitting error.

[0148] The fourth step is to normalize the maximum value in the local pilot hole risk factors under all the preset direction groups to obtain a target pilot hole risk factor.

[0149] The fifth step of determining the target guide plate deviation according to the target pilot hole risk factor and the guide plate fitting error can include the following sub-steps:

[0150] The first sub-step is to determine the sum value of the constant 1 and the target pilot hole risk factor as a target correction factor.

[0151] The second sub-step is to determine the product of the target correction factor and the guide plate fitting error as the target guide plate deviation.

[0152] For example, the formula corresponding to the target guide plate deviation can be:

[0153] F = (1 + S) x L;

[0154] wherein, F is the target guide plate deviation. S is the target pilot hole risk factor. 1 + S is the target correction factor. L is the guide plate fitting error.

[0155] It should be noted that, the larger S is, the more likely the deviation of different contact triangular facets under different preset direction groups occurs, thereby leading to the increase of the fitting error. Therefore, F can represent the final guide plate deviation, that is, the improved fitting error, and the smaller the value of F is, the better the guide plate design is.

[0156] Optionally, according to the size of the improved fitting error, a fitting error threshold value can be set, wherein the fitting error threshold value can be selected according to clinical experience or historical error size, and the recommended value is 0.05 mm. For the drill hole area whose fitting error exceeds the set threshold value, the corresponding preset direction can be marked in the model to assist in improving the structure of the guide plate. The specific improvement suggestions can include: increasing the contact area along the weak support direction around the drill hole, optimizing the fitting curved surface, or strengthening the local material thickness, etc., wherein the weak support direction can be the preset direction marked in the front. These structure improvement suggestions are helpful to improve the stability and controllability of the guide plate in actual operation, and reduce the probability of intraoperative guiding deviation.

[0157] Reference Figure 2 Based on the same inventive concept as the above method embodiments, the present application provides a digital simulation-based dental implant positioning guide plate deviation analysis system, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the above computer program is executed by the processor, the steps of a digital simulation-based dental implant positioning guide plate deviation analysis method are implemented, which can specifically include:

[0158] The acquisition and determination module 201 is configured to acquire the guide plate scanning model, the oral cavity STL model and the alveolar bone model of the patient to be detected, and determine each triangular facet of the guide plate scanning model as a guide plate triangular facet.

[0159] The determination and screening module 202 is configured to determine the oral contact error factor corresponding to each guide plate triangular facet according to the distance deviation between each guide plate triangular facet and the oral cavity STL model, and screen out the contact triangular facets from all guide plate triangular facets based on the oral contact error factor.

[0160] The target support strength determination module 203 is configured to determine the target support strength corresponding to each contact triangular facet according to the distance and direction deviation between each contact triangular facet and the alveolar bone model, and the oral contact error factor corresponding to each contact triangular facet.

[0161] The acquisition and setting module 204 is configured to acquire the drill hole axis and the guide plate fitting error, and set a preset number of preset directions according to the plane perpendicular to the drill hole axis.

[0162] The local support degree determination module 205 is configured to determine the local support degree of each contact triangular facet in each preset direction according to the projection of the target support strength corresponding to each contact triangular facet in each preset direction.

[0163] The target guide plate deviation determination module 206 is configured to determine the target guide plate deviation according to the guide plate fitting error and the local support degree of all contact triangular facets in all preset directions.

[0164] Figure 3 is a structural schematic diagram of a computer device provided by an embodiment of the present application. As shown in the example, Figure 3 the computer device 300 includes a memory 301, a processor 302, and a computer program 303 stored in the memory 301 and running on the processor 302, wherein the processor 302 executes the computer program 303, so that the computer device can execute any one of the above-mentioned digital simulation-based dental implant positioning guide plate deviation analysis methods.

[0165] Based on the same inventive concept as the above method embodiments, the present application provides a server, including a memory and a processor. The memory is used to store executable program code, and the processor is used to call and run the executable program code from the memory, so that the device executes any one of the above-mentioned digital simulation-based dental implant positioning guide plate deviation analysis methods.

[0166] Based on the same inventive concept as the above method embodiments, the present application provides a computer program product, which includes computer program code. When the computer program code runs on a computer, it makes the computer execute any one of the above-mentioned digital simulation-based dental implant positioning guide plate deviation analysis methods.

[0167] Based on the same inventive concept as the above method embodiments, the present application provides a computer-readable storage medium, which stores computer program code. When the computer program code runs on a computer, it makes the computer execute any one of the above-mentioned digital simulation-based dental implant positioning guide plate deviation analysis methods.

[0168] In summary, the present application realizes the comprehensive analysis of the high-precision three-dimensional fitting error and the deviation of the guide hole direction by reconstructing the preoperative model with the CBCT and the oral scanning data, combining the entity scanning results of the initial guide plate model. Firstly, according to the entity scanning results of the guide plate, the support strength of multiple triangular facets on the surface of the guide plate model is obtained in combination with the error size between different regions and the oral model, which is helpful to identify the regions with good structure fitting and prone to deformation; then, according to the deviation size between the obtained guide hole axis and the alveolar bone axis, the preliminary fitting error is obtained to find the potential risk of the implant direction deviation in advance; and considering that there is a great risk in the case of insufficient support and small initial deviation, the deviation of the guide hole in different directions of the guide plate is predicted by considering the difference of the support strength perpendicular to the guide hole axis, and then the fitting error is improved, and the quantitative guidance for the guide plate structure optimization is provided through the fitting error size.

[0169] The above examples are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method for analyzing deviations of dental implant positioning guides based on digital simulation, characterized in that, Includes the following steps: The guide plate scanning model, oral STL model and alveolar bone model of the patient to be tested were obtained, and each triangular facet of the guide plate scanning model was identified as a guide plate triangular facet. The guide plate scanning model was registered with the oral STL model and alveolar bone model respectively. Based on the distance deviation between each guide triangular facet and the oral STL model, the oral contact error factor corresponding to each guide triangular facet is determined, and based on the oral contact error factor, the contact triangular facets are selected from all guide triangular facets. Based on the distance and directional deviation between each contact triangle and the alveolar bone model, and the oral contact error factor corresponding to each contact triangle, the target support strength corresponding to each contact triangle is determined. Obtain the fit error between the guide hole axis and the guide plate, and set a preset number of preset directions based on the plane perpendicular to the guide hole axis; Based on the projection of the target support strength corresponding to each contact triangle in each preset direction, determine the local support degree of each contact triangle in each preset direction. The target guide plate deviation is determined based on the guide plate fitting error and the degree of local support of all contact triangular facets in all preset directions.

2. The method for analyzing deviations of dental implant positioning guides based on digital simulation according to claim 1, characterized in that, The step of determining the oral contact error factor for each guide triangular facet based on the distance deviation between each guide triangular facet and the oral STL model includes: The closest point error between each guide triangular facet and the oral STL model is determined as the oral contact error factor for each guide triangular facet.

3. The method for analyzing deviations of dental implant positioning guides based on digital simulation according to claim 1, characterized in that, The process of selecting contact triangular facets from all guide triangular facets based on the oral cavity contact error factor includes: Based on the difference between the oral contact error factors corresponding to each pair of guide triangular facets and the minimum distance between each pair of guide triangular facets, the target distance metric between each pair of guide triangular facets is determined. Based on the target distance metric between different guide plate triangular facets, all guide plate triangular facets are clustered to obtain target clusters; The mean value of the oral contact error factor corresponding to all guide triangular facets within each target cluster is determined as the oral contact representative error for each target cluster. Each guide triangular facet within the target cluster with the smallest corresponding oral contact representative error is identified as a contact triangular facet.

4. The method for analyzing deviations of dental implant positioning guides based on digital simulation according to claim 1, characterized in that, The determination of the target support strength for each contact triangle, based on the distance and directional deviation between each contact triangle and the alveolar bone model, and the oral contact error factor corresponding to each contact triangle, includes: The closest point error between each contact triangle and the alveolar bone model is determined as the tooth contact error factor for each contact triangle. From all the triangular facets of the alveolar bone model, select the triangular facet closest to the contacting triangular facet and use it as the reference triangular facet corresponding to that contacting triangular facet. The target support strength for each contact triangle is determined based on the angle between the normal direction of each contact triangle and its corresponding reference triangle, as well as the tooth contact error factor and oral contact error factor for each contact triangle.

5. The method for analyzing deviations of dental implant positioning guides based on digital simulation according to claim 1, characterized in that, The acquisition of the guide hole axis and guide plate fitting error includes: Using a circular edge detection algorithm, at least three horizontal cross-section centers are extracted from the inner wall of the guide hole in the guide plate scanning model, and straight line fitting is performed on all the extracted center points to obtain the guide hole axis. The area in the alveolar bone model where implantation is planned is identified as the target area, and bone surface contour points are extracted from the target area. Based on the extracted bone surface contour points, construct the alveolar bone axis; The minimum distance between the guide hole axis and the alveolar bone axis is defined as the guide plate fitting error.

6. The method for analyzing deviations of dental implant positioning guides based on digital simulation according to claim 1, characterized in that, The step of setting a preset number of preset directions according to the plane perpendicular to the guide hole axis includes: The plane perpendicular to the axis of the guide hole is defined as the target plane; Taking any point on the target plane as the target vertex, starting from the target vertex, draw rays with different extension directions of the target number, denoted as target rays, where the target number is equal to half of the preset number; The direction of extension of each target ray and its opposite direction are determined as preset directions.

7. The method for analyzing deviations of dental implant positioning guides based on digital simulation according to claim 1, characterized in that, The step of determining the local support level of each contact triangular facet in each preset direction based on the projection of the target support strength corresponding to each contact triangular facet in each preset direction includes: The angle between the direction of the normal of each contact triangle and each preset direction is determined as the target angle between each contact triangle and each preset direction. The cosine of the target angle between each contact triangle and each preset direction is determined as the target cosine between each contact triangle and each preset direction. The absolute value of the product of the target support strength corresponding to each contact triangle and the target cosine between each preset direction is determined as the local support level of each contact triangle in each preset direction.

8. The method for analyzing deviations of dental implant positioning guides based on digital simulation according to claim 1, characterized in that, The determination of the target guide plate deviation based on the guide plate fitting error and the local support degree of all contact triangular facets in all preset directions includes: Each pair of preset directions that are opposite to each other forms a preset direction group; Based on the difference between the degree of local support of each contact triangular facet in two preset directions in each preset direction group, and the minimum distance between each contact triangular facet and the axis of the guide hole, the local difference factor of each contact triangular facet in each preset direction group is determined. Based on the local difference factor of all contact triangular facets under the same preset direction group, determine the local guide hole risk factor under that preset direction group; The maximum value of the local guide hole risk factor under all preset direction groups is normalized to obtain the target guide hole risk factor. The target guide plate deviation is determined based on the target guide hole risk factor and the guide plate fitting error.

9. The method for analyzing deviations of dental implant positioning guides based on digital simulation according to claim 8, characterized in that, The step of determining the local via risk factor under the preset direction group based on the local difference factor of all contact triangular facets under the same preset direction group includes: The sum of the local difference factors of all contact triangular facets under the same preset direction group is determined as the local guide hole risk factor under that preset direction group.

10. The method for analyzing deviations of dental implant positioning guides based on digital simulation according to claim 8, characterized in that, The step of determining the target guide plate deviation based on the target guide hole risk factor and the guide plate fitting error includes: The sum of constant 1 and the target guide hole risk factor is determined as the target correction factor; The product of the target correction factor and the guide plate fitting error is determined as the target guide plate deviation.

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