Dental model reconstruction and verification method, appliance verification method, and electronic device

Abstract

The embodiment of the application relates to the tooth orthodontic field, and discloses a dental arch model reconstruction and verification method, an appliance verification method and an electronic device. The dental arch model reconstruction method in the embodiment of the application comprises the following steps: determining a displacement vector of a tooth, a first displacement matrix and a first stress tensor of a periodontal ligament node of the tooth under the action of a target correction force according to a tooth model, a periodontal ligament model and a first constraint condition; the first constraint condition comprises that grid nodes on the boundary of the periodontal ligament node in contact with alveolar bone are set as fixed constraints, incomplete fixed constraints or spring constraints; determining a second displacement matrix and a second stress tensor of the periodontal ligament node under the action of the first stress tensor according to the periodontal ligament model after deformation via the first displacement matrix and a second constraint condition; the second constraint condition comprises that grid nodes on the boundary of the periodontal ligament node in contact with the tooth are set as fixed constraints. The displacement prediction of the tooth in the correction process is more accurate.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of orthodontic technology, and particularly to methods for reconstructing and verifying dental models, methods for verifying orthodontic appliances, and electronic devices. Background Technology

[0002] With the increasing demand for aesthetically pleasing teeth, orthodontic treatment has gained wider attention and is increasingly used in clinical practice. Orthodontic treatment typically involves wearing braces, gradually correcting teeth over a long period without disrupting daily life or social interactions.

[0003] For each orthodontic cycle, a corresponding orthodontic appliance exists. This means that the appliance is manufactured based on the current condition of the teeth at different treatment cycles. During some procedures, it's necessary to predict tooth displacement during treatment to reconstruct the jaw model and generate the corresponding appliance. Currently, the finite element method (FEM) is mostly used for short-term prediction of instantaneous tooth movement. However, due to the limited deformation of the computational mesh within the FEM framework during treatment, applying it to long-term movement calculations can lead to excessive mesh deformation and distortion, resulting in either inaccurate or uncalculated predicted displacements. Summary of the Invention

[0004] The purpose of this invention is to provide a method for reconstructing and verifying a dental model, a method for verifying orthodontic appliances, and an electronic device that can make long-term and effective predictions of tooth movement during orthodontic treatment.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a method for reconstructing a dental model, comprising the following steps: determining the displacement vector of the tooth under the action of the target orthodontic force, the first displacement matrix of the periodontal ligament nodes, and the first stress tensor based on a tooth model of the tooth to be treated, a periodontal ligament model, and a first constraint condition; wherein, the first constraint condition includes: the mesh nodes on the boundary of the periodontal ligament nodes that contact the alveolar bone are set as fixed constraints, incomplete fixed constraints, or spring constraints; determining the second displacement matrix and the second stress tensor of the periodontal ligament nodes under the action of the first stress tensor based on the periodontal ligament model deformed by the first displacement matrix and the second constraint condition; wherein, the second constraint condition includes: the mesh nodes on the boundary of the periodontal ligament nodes that contact the tooth are set as fixed constraints.

[0006] The present invention also provides a method for verifying orthodontic appliances, comprising: predicting the displacement vector of teeth in a case after each treatment cycle based on the above-described dental model reconstruction method; wherein, the target orthodontic force is the orthodontic force provided within the target treatment cycle; if the target treatment cycle is not the first treatment cycle within multiple consecutive treatment cycles, the tooth model and periodontal ligament model of the teeth to be treated are: the tooth model and periodontal ligament model after the teeth have moved in the previous treatment cycle of the predicted target treatment cycle; determining the preset total displacement vector of the teeth according to the initial tooth model of the case and the preset target tooth model; wherein, the target tooth model refers to the model corresponding to the expected alignment state of the teeth of the case after treatment with a set of orthodontic appliances; each orthodontic appliance in a set of orthodontic appliances is used for treatment within one treatment cycle; recording the predicted displacement vector of the teeth in the case after the last treatment cycle as the predicted total displacement vector of the teeth, calculating the vector difference between the predicted total displacement vector and the preset total displacement vector, and determining that a set of orthodontic appliances is qualified if the vector difference is within a first preset range; and determining that a set of orthodontic appliances is unqualified if the vector difference is not within the first preset range.

[0007] The present invention also provides a method for verifying the above-described dental model reconstruction method, comprising: predicting the displacement vector of the teeth of a case after each orthodontic cycle based on the above-described dental model reconstruction method; wherein the predicted displacement vector of the teeth of a case after each orthodontic cycle is denoted as the predicted displacement vector of the teeth after each orthodontic cycle; monitoring the actual displacement vector of the teeth of a case after each orthodontic cycle in clinical treatment; wherein the actual displacement vector of the teeth after each orthodontic cycle and the predicted displacement vector of the teeth after each orthodontic cycle correspond one-to-one; the actual displacement vector and the predicted displacement vector of the teeth after the corresponding orthodontic cycle are referred to as a set of displacement vectors; calculating the vector difference between the actual displacement vector and the predicted displacement vector in each set of displacement vectors; if the vector difference of n sets of displacement vectors is greater than or equal to a third preset range, the dental model reconstruction method is deemed to be verified as qualified; if the vector difference of n sets of displacement vectors is less than a third preset range, the dental model reconstruction method is deemed to be verified as unqualified; n is a positive integer and less than or equal to the total number of orthodontic cycles.

[0008] Embodiments of the present invention also provide an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the above-described dental model reconstruction method, or to perform the above-described orthodontic appliance verification method, or to perform the above-described method for verifying the dental model reconstruction method.

[0009] Embodiments of the present invention also provide a computer-readable storage medium, comprising: a computer program that, when executed by a processor, implements the above-described method for reconstructing a dental model, or is capable of implementing the above-described method for verifying an orthodontic appliance, or is capable of implementing the above-described method for verifying a dental model reconstruction.

[0010] In this embodiment, a tooth model after movement according to the target orthodontic force can be obtained. At the same time, the stress redistribution process during tooth movement is taken into account, namely the process of periodontal ligament deformation and stress change caused by alveolar bone remodeling. The tooth model after movement according to the target orthodontic force and the periodontal ligament model considering alveolar bone remodeling are used together to form a dentition mesh model under the action of the target orthodontic force. Compared with the tooth model and periodontal ligament model that only move according to the target orthodontic force, the addition of the influencing factor of alveolar bone remodeling is more consistent with the actual situation and the prediction accuracy of the tooth movement process is higher.

[0011] In addition, the tooth model includes a tooth mesh model; before determining the tooth displacement vector, the first displacement matrix of the periodontal ligament node, and the first stress tensor under the target orthodontic force based on the tooth model of the tooth to be treated, the periodontal ligament model, and the first constraint condition, the method further includes: selecting multiple pairs of mesh nodes from the tooth mesh model of the tooth to be treated corresponding to the target orthodontic cycle and the orthodontic appliance mesh model corresponding to the target orthodontic cycle; wherein each pair of mesh nodes includes one mesh node located on the tooth model and one mesh node located on the orthodontic appliance mesh model; applying different orthodontic forces to the multiple pairs of mesh nodes multiple times, with one orthodontic force applied to the multiple pairs of mesh nodes each time, and calculating the target values ​​corresponding to the multiple pairs of mesh nodes under different orthodontic forces according to the pre-constructed target function; the target function is constructed based on the displacement vector difference of each pair of mesh nodes; selecting the optimal target value from the target values ​​corresponding to the multiple pairs of mesh nodes under different orthodontic forces, and using the orthodontic force applied when the optimal target value is obtained as the target orthodontic force. That is, the target value under different corrective forces is obtained according to the objective function. This target value can represent the positional difference between grid node pairs. In this case, the appropriate target corrective force can be obtained by minimizing the objective function.

[0012] Furthermore, based on the tooth model, periodontal ligament model, and first constraint conditions of the tooth to be treated, the displacement vector of the tooth, the first displacement matrix of the periodontal ligament nodes, and the first stress tensor are determined under the target orthodontic force. This includes: determining the tooth displacement vector under the target orthodontic force using the finite element method based on the tooth model of the tooth to be treated; and determining the first displacement matrix and first stress tensor of the periodontal ligament nodes using the finite element method based on the periodontal ligament model, the first constraint conditions, and the tooth displacement vector. In other words, by using the finite element method under the first constraint conditions, the displacement vector of the tooth, the first displacement matrix of the periodontal ligament nodes, and the first stress tensor are calculated under the target orthodontic force, resulting in a tooth model and periodontal ligament model that do not consider the alveolar bone remodeling process.

[0013] Furthermore, based on the periodontal ligament model deformed by the first displacement matrix and the second constraint condition, the second displacement matrix and the second stress tensor of the periodontal ligament nodes under the action of the first stress tensor are determined. This includes: using the finite element analysis method, based on the periodontal ligament model deformed by the first displacement matrix and the second constraint condition, determining the second displacement matrix and the second stress tensor of the periodontal ligament nodes under the action of the first stress tensor. That is, considering the alveolar bone reconstruction process, the first constraint condition is replaced with the second constraint condition to obtain a tooth model and a periodontal ligament model considering the alveolar bone reconstruction process. Attached Figure Description

[0014] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0015] Figure 1 This is a schematic flowchart of a method for reconstructing a dental model according to one embodiment of this application;

[0016] Figure 2 This is a flowchart illustrating a method for verifying an orthodontic appliance according to one embodiment of this application.

[0017] Figure 3 This is a flowchart illustrating a method for verifying a dental model reconstruction method according to one embodiment of this application;

[0018] Figure 4 This is a schematic diagram of the structure of an electronic device provided according to one embodiment of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the various embodiments of the present invention to facilitate a better understanding of this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The division of the various embodiments below is for ease of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with and referenced by each other without contradiction.

[0020] The terms "first" and "second" used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a system, product, or device that includes a series of components or units is not limited to the listed components or units, but may optionally include unlisted components or units, or may optionally include other components or units inherent to such products or devices. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0021] One embodiment of the present invention relates to a method for reconstructing a dental model. The specific process is as follows: Figure 1 As shown.

[0022] Step 101: Based on the tooth model, periodontal ligament model, and first constraint conditions of the tooth to be treated, determine the displacement vector of the tooth under the action of the target orthodontic force, the first displacement matrix of the periodontal ligament node, and the first stress tensor; wherein, the first constraint conditions include: the mesh nodes on the boundary of the periodontal ligament node that are in contact with the alveolar bone are set as fixed constraints, incomplete fixed constraints, or spring constraints.

[0023] Step 102: Based on the periodontal ligament model deformed by the first displacement matrix and the second constraint condition, determine the second displacement matrix and the second stress tensor of the periodontal ligament node under the action of the first stress tensor; wherein, the second constraint condition includes: the mesh nodes on the boundary of the periodontal ligament node that are in contact with the tooth are set as fixed constraints.

[0024] In this embodiment, a tooth model that moves according to the target orthodontic force can be obtained. At the same time, the alveolar bone remodeling during the orthodontic force is taken into account. The tooth model that moves according to the target orthodontic force and the periodontal ligament model that takes into account the alveolar bone remodeling are used together to form a dentition mesh model under the target orthodontic force. Compared with the tooth model and periodontal ligament model that move only according to the target orthodontic force, the addition of the influencing factor of alveolar bone remodeling is more consistent with the actual situation and the prediction accuracy of the tooth movement process is higher.

[0025] The following is a detailed description of the implementation details of the dental model reconstruction method of this embodiment. The following content is only for the convenience of understanding and is not necessary for implementing this solution.

[0026] In step 101, based on the tooth model of the tooth to be treated, the periodontal ligament model, and the first constraint condition, the displacement vector of the tooth, the first displacement matrix of the periodontal ligament node, and the first stress tensor are determined under the action of the target orthodontic force. The first constraint condition includes setting the mesh nodes on the boundary of the periodontal ligament node that contacts the alveolar bone as fixed constraints, incomplete fixed constraints, or spring constraints. That is, in the periodontal ligament node, the first constraint condition is set for the mesh nodes on the boundary facing the alveolar bone. The periodontal ligament node is the mesh node on the periodontal ligament model. The first constraint condition includes fixed constraints, incomplete constraints, or spring constraints, etc. Incomplete constraints refer to some mesh nodes being set as fixed constraints and some mesh nodes not being set as fixed constraints. The fixed mesh nodes can be pre-set in terms of scale and position, or randomly selected. The selection of mesh nodes that need to be fixed can be set according to the actual situation, and this embodiment does not limit this. The displacement vector of the tooth, the first displacement matrix of the periodontal ligament node, and the first stress tensor of the periodontal ligament model and the tooth model in contact with the periodontal ligament model are calculated under this constraint condition after the application of the target orthodontic force.

[0027] In one example, the tooth model includes a tooth mesh model. Before determining the tooth displacement vector, the first displacement matrix of the periodontal ligament node, and the first stress tensor under the target orthodontic force based on the tooth model of the tooth to be treated, the periodontal ligament model, and the first constraint condition, the method further includes: selecting multiple pairs of mesh nodes from the tooth mesh model of the tooth to be treated corresponding to the target orthodontic cycle and the orthodontic appliance mesh model corresponding to the target orthodontic cycle; wherein each pair of mesh nodes includes one mesh node located on the tooth model and one mesh node located on the orthodontic appliance mesh model; applying different orthodontic forces to the multiple pairs of mesh nodes multiple times, with one orthodontic force applied to the multiple pairs of mesh nodes each time, and calculating the target values ​​corresponding to the multiple pairs of mesh nodes under different orthodontic forces according to a pre-constructed objective function; the objective function is constructed based on the displacement vector difference of each pair of mesh nodes; selecting the optimal target value from the target values ​​corresponding to the multiple pairs of mesh nodes under different orthodontic forces, and using the orthodontic force applied when the optimal target value is obtained as the target orthodontic force. That is, first, take the mesh nodes on the tooth model and the corresponding mesh nodes on the orthodontic appliance mesh model. Use the orthodontic force applied to the corresponding mesh nodes and the change in mesh nodes under the orthodontic force as parameters to calculate the optimal solution of the pre-constructed objective function, that is, the optimal target value. Take the orthodontic force corresponding to the optimal target value as the target orthodontic force. Among them, the "multiple pairs of mesh nodes" are pre-set multiple pairs of key points. For each pair of mesh nodes (key points), it can be a mesh node on the tooth mesh model and a mesh node on the orthodontic appliance mesh model that come into contact at the beginning of the target orthodontic cycle, or it can be a mesh node on the tooth model and a mesh node on the orthodontic appliance mesh model that come into contact after the end of the target orthodontic cycle.

[0028] Specifically, when the target orthodontic cycle is the period between step n and step n+1 in the orthodontic process, the mesh nodes on the appliance mesh model at step n+1 are bound to the corresponding mesh nodes on the tooth mesh model at step n, resulting in multiple pairs of bound mesh nodes. These multiple pairs of bound mesh nodes can be considered as a set of mesh node pairs. Here, a bound mesh node pair can represent the relationship between a mesh node on the tooth mesh model and a mesh node on the appliance mesh model that is in contact, about to contact, or will contact after the target orthodontic cycle ends; establishing The objective function is to optimize the shape difference between the tooth mesh model and the orthodontic appliance mesh model. The magnitude and direction of the contact force on the mesh nodes of the orthodontic appliance mesh model are used as independent variables. The direction of the contact force can be the three-axis direction in the global coordinate system. The parameter representing the shape difference between the tooth mesh model and the orthodontic appliance mesh model is used as the dependent variable. The objective function is optimized by minimizing the objective function. The calculated optimal solution (that is, the optimal objective value) is the target orthodontic force of the tooth mesh model. The optimal solution corresponds to the contact force on the mesh nodes of the orthodontic appliance mesh model that has the same magnitude but opposite direction. In the calculation of the objective function, multiple calculations can be performed, each using a different orthodontic force, to calculate the shape difference between the corresponding tooth mesh model and the appliance mesh model. Furthermore, when calculating the shape difference based on the orthodontic force in a single calculation—that is, when calculating the shape difference corresponding to a set of binding constraint mesh nodes—an orthodontic force needs to be applied to each pair of binding constraint mesh nodes in the chosen set. This orthodontic force includes the orthodontic force corresponding to each pair of binding constraint mesh nodes. For example, if there are 10 pairs of binding constraint mesh nodes in a set, then the orthodontic force includes the orthodontic force corresponding to each of the 10 pairs of mesh nodes. The orthodontic forces applied to each pair of mesh nodes can be the same or different.

[0029] In this context, the corrective force can be understood as the contact force on the orthodontic appliance mesh model, where the force is the same in magnitude but opposite in direction. When the contact force on the mesh nodes of the orthodontic appliance mesh model is taken as the independent variable, the tooth mesh model remains unchanged. The calculation optimizes the force on the mesh nodes of the orthodontic appliance, and then reverses this to obtain the force on the corresponding mesh nodes of the tooth mesh model. Therefore, if the magnitude and direction of the contact force on the mesh nodes of the tooth mesh model are directly used in the calculation process, instead of the magnitude and direction of the contact force on the mesh nodes of the orthodontic appliance mesh model, as the dependent variable of the objective function, after obtaining the optimal target value, it is not necessary to reverse the force corresponding to the optimal target value; the target corrective force of the tooth mesh model can be directly obtained.

[0030] In a specific implementation, the appliance mesh model at step n+1 refers to the appliance mesh model used to achieve the target position of the tooth moving from step n to step n+1. The corresponding mesh nodes on the tooth mesh model and the appliance mesh model are pre-selected key points that can be used to calibrate and calculate the differences between the tooth surface shape and the appliance surface shape. During the wearing process, the teeth and the appliance will try to keep in close contact, and correspondingly, the selected mesh nodes (key points) on the tooth mesh model and the appliance mesh model will also try to keep in contact. The sets of key points corresponding to the tooth mesh model and the appliance mesh model can describe the shape of the tooth and the appliance respectively, and the sum of the squares of the differences between all corresponding key points can describe the difference between the shape of the tooth and the shape of the appliance.

[0031] In one example, the objective function can be constructed based on the sum of the squares of the displacement vector differences between each pair of mesh nodes (each pair of key points) in a set of mesh node pairs. That is, the sum of the squares of the displacement vector differences is used as the dependent variable of the objective function. Alternatively, the square root of the sum of the squares of the displacement vector differences between each pair of key points, or the numerical summation of the displacement vector differences between each pair of key points, can also be used as the dependent variable of the objective function, i.e., as the target parameter to be optimized during the calculation process. In a specific implementation, the optimal objective value of the objective function is obtained under the constraint condition that the tooth mesh model and the orthodontic mesh model do not penetrate each other. Whether penetration has occurred can be determined by the vector difference between the mesh nodes in the tooth mesh model and the mesh nodes in the orthodontic mesh model. For example, taking the tooth mesh model as the reference, the vector value of the mesh node on the tooth mesh model pointing to the corresponding mesh node on the orthodontic mesh model is taken, and the direction of each point on the tooth mesh model pointing into the tooth mesh model is defined as the negative direction, and the direction pointing out of the tooth mesh model is defined as the positive direction. If the vector value points in the negative direction, it means that penetration has occurred between the tooth mesh model and the orthodontic mesh model; otherwise, penetration has not occurred. Alternatively, a similar judgment can be made based on the orthodontic mesh model. Calculating the objective function under constraints better reflects the actual situation and improves the practicality of parameter calculations.

[0032] In one example, the tooth model includes a tooth mesh model and a tooth constitutive model; the periodontal ligament model includes a periodontal ligament mesh model and a periodontal ligament constitutive model. The constitutive models of the tooth and periodontal ligament may include the material properties of the tooth and the periodontal ligament. Additionally, this embodiment may also include a constitutive model of an orthodontic appliance, such as the material properties of the appliance; and the appliance mesh model and the appliance constitutive model can form an appliance model.

[0033] Specifically, the dental mesh model can be a standardized dental mesh, a dental mesh obtained from an intraoral scan of the case, or a dental mesh model data reconstructed in 3D after a cone-beam CT (CBCT) scan of the case. The dental mesh model includes a crown mesh model and a root mesh model. One side of the root mesh model contacts the periodontal ligament mesh model, and the other side contacts the alveolar bone. The root mesh model can be a root mesh model reconstructed in 3D after a CBCT scan, or a root mesh model generated by an algorithm using crown and standardized root data. The orthodontic appliance mesh model is a mesh model designed in stages. The staged design of the orthodontic appliance can be based on the orthodontic staged tooth arrangement plan developed by the dentist for the case. The periodontal ligament mesh model can be an automatically generated mesh model based on root outer surface data using preset rules. In addition, the material properties of teeth include density, elastic modulus, and Poisson's ratio; the material properties of orthodontic appliances include density, elastic modulus, Poisson's ratio, yield strength, tensile strength, hardening parameters, and other calibration parameters related to the constitutive model of the appliance material; the material properties of the periodontal ligament include elastic modulus, Poisson's ratio, density, and other calibration parameters related to the constitutive model of the periodontal ligament material. The material properties of teeth can be obtained by consulting relevant medical manuals and literature, while the material properties of orthodontic appliances can be determined experimentally for different appliance products. The material properties of the periodontal ligament can also be obtained through experimental testing; and all of the above parameters can be manually input.

[0034] In addition, various boundary conditions can be set for each model according to the actual situation, so that the calculation results are more consistent with the actual situation and the effectiveness of the predicted movement results can be increased. For the tooth model, the contact boundary conditions between the tooth and the appliance, the contact boundary conditions between the root and the periodontal ligament, and the boundary conditions for the application of orthodontic force on the tooth can be set; for the appliance model, the boundary conditions for the contact force and displacement between the appliance and the tooth can be set; for the periodontal ligament model, the constraint boundary conditions for the contact between the outer surface of the periodontal ligament and the alveolar bone, and the contact boundary conditions between the periodontal ligament and the root can be set.

[0035] In one example, based on the tooth model, periodontal ligament model, and first constraint conditions of the tooth to be treated, the displacement vector of the tooth, the first displacement matrix of the periodontal ligament node, and the first stress tensor are determined under the target orthodontic force. This includes: determining the tooth displacement vector under the target orthodontic force using the finite element method based on the tooth model of the tooth to be treated; and determining the first displacement matrix and first stress tensor of the periodontal ligament node using the finite element method based on the periodontal ligament model, the first constraint conditions, and the tooth displacement vector. That is, the displacement vector of the tooth under the target orthodontic force is calculated, and the results include: the tooth displacement vector, the first displacement matrix of the periodontal ligament node, and the first stress tensor. The displacement vector of the tooth under the target orthodontic force refers to the calculation based on the finite element model established in this step, using the finite element method. This calculation process can be performed using static solutions, i.e., considering the static displacement solution under a single loading of the target orthodontic force. After obtaining the tooth displacement vector, based on the tooth displacement vector, the periodontal ligament model, and the aforementioned first constraint condition, the first displacement matrix and the first stress tensor of the periodontal ligament nodes are obtained through finite element analysis. The tooth displacement vector includes the displacement and rotation along the three axes in the tooth's global coordinate system; the stress tensor of the periodontal ligament nodes includes the six stress components of the periodontal ligament, namely the normal stress and shear stress along the three axes; the displacement matrix of the periodontal ligament nodes includes the displacement and rotation of all nodes on the periodontal ligament along the three axes.

[0036] In step 102, based on the periodontal ligament model deformed by the first displacement matrix and the second constraint condition, the second displacement matrix and the second stress tensor of the periodontal ligament nodes under the action of the first stress tensor are determined; wherein, the second constraint condition includes: the mesh nodes on the boundary of the periodontal ligament node in contact with the tooth are set as fixed constraints. That is, after applying the aforementioned target orthodontic force and obtaining the periodontal ligament model that changes under the action of the target orthodontic force, the second displacement matrix and the second stress tensor of the periodontal ligament nodes are further determined based on the changed periodontal ligament model, the second constraint condition, and the first stress tensor. This allows for the acquisition of a periodontal ligament model that considers alveolar bone remodeling.

[0037] In one example, based on the periodontal ligament model deformed by the first displacement matrix and the second constraint condition, the second displacement matrix and the second stress tensor of the periodontal ligament node under the action of the first stress tensor are determined. This includes: using the finite element analysis method, based on the periodontal ligament model deformed by the first displacement matrix and the second constraint condition, to determine the second displacement matrix and the second stress tensor of the periodontal ligament node under the action of the first stress tensor. That is, based on the changed periodontal ligament model obtained from the target orthodontic force and the second constraint condition, the first constraint condition is no longer considered, and the change state of the periodontal ligament under the first stress tensor is determined by referring to the finite element analysis method.

[0038] Specifically, after obtaining the periodontal ligament model based on the changes in the target orthodontic force, the constraints are redefined, that is, the first constraint is changed to the second constraint, allowing the stress in the periodontal ligament model to be released, resulting in springback deformation on the outer side of the periodontal ligament model (the boundary in contact with the alveolar bone). This solves the problem of excessive mesh deformation in long-term prediction and also describes the stress redistribution and deformation changes in the periodontal ligament model caused by alveolar bone remodeling. The calculated results include: the second stress tensor of the periodontal ligament nodes, the second displacement matrix of the periodontal ligament nodes, and, in this calculation, the tooth displacement vector remains unchanged with the first displacement vector.

[0039] In this step, redefining the constraints means that, in the calculation, the mesh nodes on the side of the tooth model and periodontal ligament nodes that are in contact with the tooth are defined as fixed constraints. That is, the relative movement between the tooth model and the periodontal ligament model is not considered, and the relative position between the mesh nodes on the tooth-facing side of the periodontal ligament model and the tooth model is assumed to remain unchanged. The constraints on the mesh nodes on the alveolar bone side of the periodontal ligament model are relaxed, that is, the first constraint is disregarded, and the periodontal ligament nodes in contact with the alveolar bone are allowed to undergo stress release and springback deformation. Since the stress of the periodontal ligament model will be redistributed and deformed after the alveolar bone is remodeled, this keeps the periodontal ligament model within a reasonable deformation range, so that the deformation is not too large and will damage the usability of the periodontal ligament model.

[0040] Furthermore, this step refers to calculating new parameters related to the periodontal ligament model based on the periodontal ligament model and the first stress tensor after redefining the constraints, according to the above calculation based on the periodontal ligament model and the change of the target orthodontic force. These parameters include the second stress tensor and the second displacement matrix of the periodontal ligament nodes. The obtained second stress tensor and second displacement matrix include the components described in the first stress tensor and the first displacement matrix, which will not be repeated here.

[0041] In one example, in the steps of determining the tooth displacement vector, the first displacement matrix of the periodontal ligament node, and the first stress tensor under the target orthodontic force based on the tooth model, periodontal ligament model, and first constraint conditions, the first strain tensor corresponding to the first stress tensor is also determined. Similarly, in the steps of determining the second displacement matrix and the second stress tensor of the periodontal ligament node under the first stress tensor based on the periodontal ligament model deformed by the first displacement matrix and the second constraint conditions, the second strain tensor corresponding to the second stress tensor is also determined. That is, after each stress tensor acquisition, the corresponding strain tensor can be calculated to demonstrate the characteristics of the periodontal ligament model. Specifically, after obtaining the first stress tensor, the first strain tensor can be calculated from it; after obtaining the second stress tensor, the second strain tensor can be obtained from it, and so on. The periodontal ligament strain tensor can include the six strain components of the periodontal ligament: normal strain and shear strain along the three axes.

[0042] In one example, the target orthodontic force is the force provided within the target treatment cycle. If the target treatment cycle is a non-first treatment cycle within multiple consecutive treatment cycles, the tooth model and periodontal ligament model of the tooth to be treated are: the tooth model and periodontal ligament model after tooth movement in the previous treatment cycle of the predicted target treatment cycle. For example, if the target treatment cycle is the treatment process between step i and step i+1, then the tooth model of the tooth to be treated is the tooth model after step i in the previous treatment cycle, and the periodontal ligament model of the tooth to be treated is the periodontal ligament model after step i in the previous treatment cycle. That is, multiple treatment cycles are allowed, and in each treatment cycle, the periodontal ligament model and tooth model obtained in the previous treatment cycle are used as initial values ​​for calculation, and the process is iterated sequentially. This implementation supports accurate prediction of the long-term tooth movement process.

[0043] Referring to the above execution steps, for example, after obtaining the second displacement matrix and the second stress tensor of the periodontal ligament node, the target orthodontic force in the next orthodontic cycle is calculated based on the tooth model that changes according to the target orthodontic force in this orthodontic cycle, the periodontal ligament model deformed according to the second displacement matrix, and the first constraint condition. Then, the new displacement vector of the tooth model, the third stress tensor of the periodontal ligament node, the third strain tensor of the periodontal ligament node, the third displacement matrix of the periodontal ligament node, and other parameters of the periodontal ligament node are obtained step by step under the target orthodontic force in the next orthodontic cycle.

[0044] In this embodiment, a tooth model that moves according to the target orthodontic force can be obtained. At the same time, the alveolar bone remodeling during the orthodontic force is taken into account. The tooth model that moves according to the target orthodontic force and the periodontal ligament model that takes into account the alveolar bone remodeling are used together to form a dentition mesh model under the target orthodontic force. Compared with the tooth model and periodontal ligament model that move only according to the target orthodontic force, the addition of the influencing factor of alveolar bone remodeling is more consistent with the actual situation and the prediction accuracy of the tooth movement process is higher.

[0045] The steps of the various methods described above are only for clarity. In practice, they can be combined into one step or some steps can be split into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this patent. Adding insignificant modifications or introducing insignificant designs to the algorithm or process, but without changing the core design of the algorithm and process, are also within the scope of protection of this patent.

[0046] One embodiment of this application relates to a method for verifying orthodontic appliances. The specific process is as follows: Figure 2 As shown, it includes:

[0047] Step 201: Based on the jaw model reconstruction method of the above-described method embodiment, predict the tooth displacement vector of the case after each treatment cycle; wherein, the target orthodontic force is the orthodontic force provided within the target treatment cycle; if the target treatment cycle is not the first treatment cycle within multiple consecutive treatment cycles, the tooth model and periodontal ligament model of the tooth to be treated are: the tooth model and periodontal ligament model after the tooth movement in the previous treatment cycle of the predicted target treatment cycle. That is, the tooth position after each treatment cycle is predicted for comparison with the actual situation to verify the accuracy of the prediction results; and multiple treatment cycles are allowed.

[0048] In one example, after predicting the tooth displacement vectors at the end of each treatment cycle, the process further includes: determining the intermediate step-by-step preset displacement vectors of the teeth based on the initial tooth model and the preset intermediate step-by-step tooth models of the case; wherein, each intermediate step-by-step tooth model corresponds one-to-one with each treatment cycle except the last treatment cycle; the predicted tooth displacement vectors at the end of each treatment cycle except the last treatment cycle are denoted as the intermediate step-by-step predicted displacement vectors of the teeth, and each intermediate step-by-step predicted displacement vector corresponds one-to-one with each intermediate step-by-step preset displacement vector, and the corresponding intermediate step-by-step predicted displacement vector and intermediate step-by-step preset displacement vector are called a set of displacement vectors; calculating the vector difference between the intermediate step-by-step predicted displacement vector and the intermediate step-by-step preset displacement vector in each set of displacement vectors; if the vector difference of the set of displacement vectors is within a second preset range, the orthodontic appliance corresponding to the set of displacement vectors is deemed to be qualified; if the vector difference of the set of displacement vectors is not within the second preset range, the orthodontic appliance corresponding to the set of displacement vectors is deemed to be unqualified. That is, there is an initial tooth model before the case undergoes orthodontic treatment, and intermediate step tooth models corresponding to the step-by-step treatment process described above; the displacement vector between the predicted tooth and the initial tooth model after each treatment cycle is denoted as the intermediate step predicted displacement vector, and the displacement vector between each intermediate step tooth model and the initial tooth model is denoted as the intermediate step preset displacement vector. If, after the end of a certain treatment cycle, the vector difference between the intermediate step predicted displacement vector and the intermediate step preset displacement vector corresponding to that treatment cycle is within a second preset range, then the orthodontic appliance corresponding to that treatment cycle is qualified; otherwise, it is judged as unqualified.

[0049] Since this step involves predicting the orthodontic appliances used in intermediate steps, including relevant parameters for each intermediate step of the orthodontic process, the verification process after the last orthodontic cycle is not considered in this step.

[0050] It can accurately determine the orthodontic appliance corresponding to each treatment cycle, further reducing deviations in the treatment process, ensuring the success rate of the treatment, and improving the user experience.

[0051] Step 202: Based on the initial tooth model and the preset target tooth model of the case, determine the preset total displacement vector of the teeth. The target tooth model refers to the model corresponding to the expected alignment of the teeth after treatment with a set of orthodontic appliances. Each appliance in a set of appliances is used for treatment within one treatment cycle. That is, without considering the above-mentioned treatment process, the preset total displacement vector is obtained by subtracting the relevant position points of the initial tooth model and the target tooth model before treatment, and can be compared with the predicted results after the treatment process.

[0052] Step 203: The predicted tooth displacement vector at the end of the last treatment cycle is recorded as the predicted total tooth displacement vector. The vector difference between the predicted total displacement vector and the preset total displacement vector is calculated. If the vector difference is within the first preset range, the orthodontic appliance is deemed to have passed verification; if the vector difference is not within the first preset range, the orthodontic appliance is deemed to have failed verification. In other words, the preset displacement vector when moving the initial tooth model to the target tooth model is compared with the predicted displacement vector at the end of all treatment cycles predicted in the above method embodiment. If the difference between the predicted displacement vector and the preset displacement vector is within an allowable range, such as within the first preset range, it means that the initial tooth model can be moved to the target tooth model according to the prediction result, and that the orthodontic appliance generated according to each predicted treatment cycle is qualified.

[0053] In this embodiment, the vector difference between the target tooth model and the initial tooth model is compared with the displacement vector of the predicted treatment cycle according to the above method embodiment. This determines whether the execution of the prediction process can achieve the target tooth model, thereby performing closed-loop correction on the prediction process to ensure that the effect of the orthodontic appliance generated according to the above method embodiment meets the expected effect, further improving the user experience. Specifically, the effect of one set of orthodontic appliances can be verified throughout the entire execution process based on the vector difference between the predicted total displacement vector and the preset total displacement vector, or the effect of the orthodontic appliance in each treatment cycle can be verified step by step.

[0054] One embodiment of this application relates to a method for validating a dental model reconstruction method. The specific process is as follows: Figure 3 As shown, it includes:

[0055] Step 301: Based on the above embodiment of the dental model reconstruction method, predict the displacement vector of the teeth in the case after each orthodontic cycle; wherein, the predicted displacement vector of the teeth in the case after each orthodontic cycle is denoted as the predicted displacement vector of the teeth after each orthodontic cycle; that is, obtain the predicted displacement vector of the corresponding teeth after each orthodontic cycle according to the above method embodiment.

[0056] Step 302: Monitor the actual displacement vector of the teeth after each treatment cycle in the clinical orthodontic treatment of the case; wherein, the actual displacement vector of the teeth after each treatment cycle corresponds one-to-one with the predicted displacement vector of the teeth after each treatment cycle; the actual displacement vector and predicted displacement vector of the teeth after the corresponding treatment cycle are called a set of displacement vectors; that is, obtain the actual displacement vector of the teeth corresponding to each of the aforementioned treatment cycles in the clinical experiment.

[0057] Step 303: Calculate the vector difference between the actual displacement vector and the predicted displacement vector in each group of displacement vectors. If the vector difference of n groups of displacement vectors is greater than or equal to the third preset range, the tooth and jaw model reconstruction method is deemed to be qualified. If the vector difference of less than n groups of displacement vectors is within the third preset range, the tooth and jaw model reconstruction method is deemed to be unqualified. n is a positive integer and less than or equal to the total number of treatment cycles. That is, the actual displacement vector in each treatment cycle of the acquired clinical data is used as the standard to determine whether the predicted displacement vector of the corresponding tooth after each treatment cycle is accurate. For example, whether the error value with the clinical data is within the third preset range. If it is within the third preset range, it is deemed accurate, that is, the prediction result of the tooth and jaw reconstruction method is accurate, and the tooth and jaw reconstruction method is qualified.

[0058] Specifically, since there are multiple sets of vector differences, the accuracy can be judged based on the number of sets of vector differences within the third preset range. If the number of sets of vector differences within the third preset range is greater than or equal to n, the tooth and jaw model reconstruction method is deemed to be qualified; if the number of sets of vector differences within the third preset range is less than n, it is deemed to be unqualified. n is a positive integer set according to the actual situation or preset by the system, and n does not exceed the total number of vector differences obtained, which is also not more than the total number of treatment cycles.

[0059] In this embodiment, the tooth displacement vectors at the end of each clinical orthodontic cycle are used as a standard to determine whether the predicted tooth displacement vectors during the implementation of the above-mentioned jaw model reconstruction method are accurate. This verifies the prediction results after the method is executed, ensures the effectiveness of the method, and improves the user experience. Specifically, the tooth displacement results in each orthodontic cycle during the method execution can be judged. A set of vector differences can be obtained for each cycle, and an unqualified threshold for the vector differences can be set, i.e., the number of unqualified sets allowed. If the number of sets exceeds this threshold, the jaw model reconstruction method is deemed unqualified.

[0060] One embodiment of the present invention relates to an electronic device, such as... Figure 4 As shown, it includes at least one processor 401; and a memory 402 communicatively connected to the at least one processor 401; wherein the memory 402 stores instructions that can be executed by the at least one processor 401, the instructions being executed by the at least one processor 401 to enable the at least one processor 401 to perform the above-described dental model reconstruction method, or to perform the above-described orthodontic appliance verification method, or to perform the above-described method for verifying the dental model reconstruction method.

[0061] The memory and processor are connected via a bus, which can include any number of interconnecting buses and bridges, connecting various circuits of one or more processors and memories. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0062] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0063] One embodiment of the present invention relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the above-described method for reconstructing a dental model, or is capable of implementing the above-described method for verifying an orthodontic appliance, or is capable of implementing the above-described method for verifying a dental model reconstruction.

[0064] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0065] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A method of dental cast reconstruction, characterized in that, The method comprises the following steps: According to the tooth model of the tooth to be treated, the displacement vector of the tooth under the action of the target treatment force is determined by using the finite element analysis method, and the first displacement matrix and the first stress tensor of the periodontal ligament node are determined by using the finite element analysis method according to the periodontal ligament model of the tooth to be treated, the first constraint condition and the displacement vector of the tooth; wherein the first constraint condition comprises: the grid nodes on the boundary of the periodontal ligament node in contact with the alveolar bone are set as fixed constraint, incomplete fixed constraint or spring constraint; According to the periodontal ligament model deformed via the first displacement matrix and the second constraint condition, the second displacement matrix and the second stress tensor of the periodontal ligament node under the action of the first stress tensor are determined; wherein the second constraint condition comprises: the grid nodes on the boundary of the periodontal ligament node in contact with the tooth are set as fixed constraint.

2. The dental cast reconstruction method according to claim 1, characterized in that, The tooth model comprises a tooth grid model; before the step of determining the displacement vector of the tooth under the action of the target treatment force according to the tooth model of the tooth to be treated by using the finite element analysis method, and determining the first displacement matrix and the first stress tensor of the periodontal ligament node by using the finite element analysis method according to the periodontal ligament model of the tooth to be treated, the first constraint condition and the displacement vector of the tooth, the method further comprises the following steps: A plurality of pairs of grid nodes are selected from the tooth grid model of the tooth to be treated corresponding to the target treatment period and the aligner grid model corresponding to the target treatment period; wherein each pair of grid nodes comprises one grid node located on the tooth model and one grid node located on the aligner grid model; Different treatment forces are applied to the plurality of pairs of grid nodes in multiple times, and each time a treatment force is applied to the plurality of pairs of grid nodes, and the target values corresponding to the plurality of pairs of grid nodes under different treatment forces are calculated according to a pre-constructed objective function; the objective function is constructed according to the displacement vector difference of each pair of grid nodes; The optimal target value is selected from the target values corresponding to the plurality of pairs of grid nodes under different treatment forces, and the treatment force applied when the optimal target value is obtained is taken as the target treatment force.

3. The dental cast reconstruction method according to claim 2, characterized in that, The objective function is specifically constructed according to the sum of squares of the displacement vector difference of each pair of grid nodes in a group of grid node pairs.

4. The dental cast reconstruction method of claim 1, wherein, The tooth model comprises a tooth grid model and a tooth constitutive model; the periodontal ligament model comprises a periodontal ligament grid model and a periodontal ligament constitutive model.

5. The dental cast reconstruction method according to claim 4, characterized in that, According to the periodontal ligament model deformed via the first displacement matrix and the second constraint condition, the second displacement matrix and the second stress tensor of the periodontal ligament node under the action of the first stress tensor are determined; wherein the second constraint condition comprises: the grid nodes on the boundary of the periodontal ligament node in contact with the tooth are set as fixed constraint. According to the periodontal ligament model deformed via the first displacement matrix and the second constraint condition, the second displacement matrix and the second stress tensor of the periodontal ligament node under the action of the first stress tensor are determined; wherein the second constraint condition comprises: the grid nodes on the boundary of the periodontal ligament node in contact with the tooth are set as fixed constraint.

6. The dental cast reconstruction method of claim 1, wherein, The target treatment force is a treatment force provided in a target treatment period; if the target treatment period is a non-first treatment period in a plurality of continuous treatment periods, the tooth model and the periodontal ligament model of the tooth to be treated are: a tooth model and a periodontal ligament model after tooth movement in a last treatment period of the target treatment period.

7. The dental model reconstruction method of claim 1, wherein, In the step of determining the first displacement matrix and the first stress tensor of the periodontal ligament node according to the periodontal ligament model, the first constraint condition and the displacement vector of the tooth under the action of the target treatment force by using the finite element analysis method, a first strain tensor corresponding to the first stress tensor is also determined. In the step of determining the second displacement matrix and the second stress tensor of the periodontal ligament node under the action of the first stress tensor according to the periodontal ligament model after deformation via the first displacement matrix and the second constraint condition, a second strain tensor corresponding to the second stress tensor is also determined.

8. A method of verifying an appliance, characterized by, The method comprises: Based on the dental model reconstruction method according to any one of claims 1 to 5 and 7, the displacement vector of the teeth of the case after the end of each treatment period is predicted; wherein the target treatment force is a treatment force provided in a target treatment period; if the target treatment period is a non-first treatment period in a plurality of continuous treatment periods, the tooth model and the periodontal ligament model of the tooth to be treated are: a tooth model and a periodontal ligament model after tooth movement in a last treatment period of the target treatment period; According to the initial tooth model of the case and the preset target tooth model, the preset total displacement vector of the teeth is determined; wherein the target tooth model refers to a model corresponding to the arrangement state of the teeth of the case after being treated by a set of appliances; each appliance in the set of appliances is used for treatment in a treatment period; The displacement vector of the teeth of the case after the end of the last treatment period is predicted as the predicted total displacement vector of the teeth, the vector difference between the predicted total displacement vector and the preset total displacement vector is calculated, if the vector difference is within a first preset range, it is determined that the set of appliances is verified to be qualified; if the vector difference is not within the first preset range, it is determined that the set of appliances is verified to be unqualified.

9. The method of claim 8, wherein, The displacement vector of the teeth of the case after the end of each treatment period further comprises: According to the initial tooth model of the case and the preset intermediate step-by-step tooth models, intermediate step-by-step preset displacement vectors of the teeth are determined; wherein each intermediate step-by-step tooth model corresponds to each of the treatment cycles except the last one; the predicted displacement vectors of the teeth at the end of each of the treatment cycles except the last one are recorded as intermediate step-by-step predicted displacement vectors of the teeth, which correspond to the intermediate step-by-step preset displacement vectors one by one, and the corresponding intermediate step-by-step predicted displacement vector and intermediate step-by-step preset displacement vector are referred to as a group of displacement vectors; The vector difference between the intermediate step-by-step predicted displacement vector and the intermediate step-by-step preset displacement vector in each group of displacement vectors is calculated; if the vector difference of the group of displacement vectors is within a second preset range, it is determined that the aligner corresponding to the group of displacement vectors is verified to be qualified, and if the vector difference of the group of displacement vectors is not within the second preset range, it is determined that the aligner corresponding to the group of displacement vectors is verified to be unqualified.

10. A method for verifying the method for dental cast reconstruction according to any one of claims 1 to 7, characterized in that, It comprises: Based on the dental model reconstruction method of any one of claims 1 to 7, the displacement vectors of the teeth at the end of each treatment cycle are predicted; wherein the predicted displacement vectors of the teeth at the end of each treatment cycle are recorded as the predicted displacement vectors of the teeth at the end of each treatment cycle; The actual displacement vectors of the teeth at the end of each treatment cycle in the clinical treatment of the case are monitored; wherein the actual displacement vectors of the teeth at the end of each treatment cycle correspond to the predicted displacement vectors of the teeth at the end of each treatment cycle one by one; the corresponding actual displacement vector and predicted displacement vector of the teeth at the end of each treatment cycle are referred to as a group of displacement vectors; The vector difference between the actual displacement vector and the predicted displacement vector in each group of displacement vectors is calculated; if the vector difference of more than or equal to n groups of displacement vectors is within a third preset range, it is determined that the dental model reconstruction method is verified to be qualified; if the vector difference of less than n groups of displacement vectors is within the third preset range, it is determined that the dental model reconstruction method is verified to be unqualified; n is a positive integer and less than or equal to the total number of treatment cycles.

11. An electronic device, comprising: It comprises: At least one processor; And The memory is in communication connection with the at least one processor; wherein The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the dental model reconstruction method of any one of claims 1 to 7, or to execute the aligner verification method of any one of claims 8 to 9, or to execute the method of verifying the dental model reconstruction method of claim 10.

12. A computer readable storage medium storing a computer program, wherein the computer program comprises program instructions configured to cause a processor to perform the method according to any one of claims 1 to 11. The computer program is executed by the processor to implement the dental model reconstruction method of any one of claims 1 to 7, or to implement the aligner verification method of any one of claims 8 to 9, or to implement the method of verifying the dental model reconstruction method of claim 10.

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