Dental orthodontic process simulation method and orthodontic scheme determination method

Abstract

The embodiment of the invention relates to the field of tooth orthodontics, and discloses a simulation method of a tooth orthodontic process and a determination method of an orthodontic scheme. The method comprises the following steps: S1, acquiring a dentition finite element mesh model, wherein the dentition finite element mesh model comprises finite element mesh models of teeth and periodontal ligament; s2, applying an orthodontic load to teeth in the dentition finite element model, and obtaining the initial movement amount of the teeth and the stress of the periodontal membrane; s3, obtaining a relation function between the alveolar bone unit reconstruction amount and the periodontal ligament stress, and calculating the alveolar bone reconstruction amount and reconstruction direction in unit time based on the relation function and the periodontal ligament stress obtained in the step S2; and S4, generating a simulated dentition model according to the initial movement amount, the alveolar bone reconstruction amount and the reconstruction direction. The actual orthodontic effect of the teeth can be obtained more comprehensively, so that the judgment on the orthodontic effect of tooth orthodontics is more accurate.

Description

Technical Field

[0001] This application relates to the field of orthodontic technology, and in particular to a method for simulating the orthodontic process and a method for determining the treatment plan. Background Technology

[0002] With the continuous development of society, orthodontics is being adopted by more and more people. Orthodontics is for the treatment of malocclusion or malalignment of teeth. It uses fixed orthodontic appliances composed of archwires, brackets, etc., or removable invisible orthodontic appliances to apply three-dimensional orthodontic forces and torques to the teeth, adjust the balance and coordination between facial bones, teeth and maxillofacial muscles, and improve facial appearance, straighten teeth and improve chewing efficiency after a period of treatment.

[0003] In existing virtual treatment design processes, engineers and clinicians typically design orthodontic plans and use virtual demonstrations to show patients the changes before and after treatment, thus helping them better understand the plan. However, due to the complexity of the oral environment, inappropriate orthodontic tools, or other reasons, there is often a discrepancy between the designed plan and the actual treatment results. The actual tooth movement cannot be accurately simulated, leading to less than ideal treatment outcomes and patient dissatisfaction.

[0004] Therefore, how to provide a method for accurately simulating the orthodontic process is an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a method for simulating the orthodontic process and determining the treatment plan that effectively solves the above-mentioned problems, thereby addressing the issue of insufficient accuracy in simulating the orthodontic process in the prior art.

[0006] To achieve the above objectives, embodiments of this application provide a method for simulating the orthodontic process, comprising:

[0007] Step S1: Obtain the finite element mesh model of the dental arch, wherein the finite element mesh model of the dental arch includes the finite element mesh models of teeth and periodontal ligament;

[0008] Step S2: Apply orthodontic load to the teeth in the finite element model of the dental arch to obtain the initial movement of the teeth and the stress of the periodontal ligament;

[0009] Step S3: Obtain the relationship function between alveolar bone unit reconstruction amount and periodontal ligament stress, and calculate the alveolar bone reconstruction amount and reconstruction direction per unit time based on the relationship function and the periodontal ligament stress obtained in step S2.

[0010] Step S4: Generate a simulated dental arch model based on the initial movement amount, the alveolar bone reconstruction amount, and the reconstruction direction.

[0011] Preferably, in the finite element mesh model of the dental arch, the nodes on the side of the tooth root adjacent to the periodontal ligament and the nodes on the side of the periodontal ligament adjacent to the tooth root are bound together.

[0012] Preferably, step S2 further includes: obtaining a finite element model of the dental arch after deformation under the instantaneous application of orthodontic load.

[0013] Preferably, step S4 includes: applying the alveolar bone reconstruction amount calculated in step S3 as a displacement loading condition to the periodontal ligament surface nodes in the deformed dentition finite element model obtained in step S2, and calculating the simulated dentition model according to the reconstruction direction.

[0014] Preferably, the periodontal ligament stress in the relationship function between the unit reconstruction amount of alveolar bone and the periodontal ligament stress is the periodontal ligament principal stress or the periodontal ligament hydrostatic pressure.

[0015] Preferably, the alveolar bone reconstruction amount per unit time is calculated based on the relationship function and the periodontal ligament stress obtained in step S2, including calculating the average hydrostatic pressure of the target periodontal ligament node according to the hydrostatic pressure of the target periodontal ligament node and its adjacent periodontal ligament nodes. When the average hydrostatic pressure is greater than a first preset threshold, the alveolar bone reconstruction amount is obtained by the first preset threshold and the average hydrostatic pressure.

[0016] Preferably, the alveolar bone reconstruction amount per unit time is calculated based on the functional relationship and the stress of the periodontal ligament, including: calculating the average principal stress of the target periodontal ligament node based on the principal stress of the target periodontal ligament node and its adjacent periodontal ligament nodes; when the average principal stress is greater than a second preset threshold, the alveolar bone reconstruction amount is obtained by the preset second preset threshold and the average principal stress.

[0017] Preferably, the method further includes: Step S5: Obtaining the treatment duration; determining the number of cycles based on the treatment duration and the unit time; repeating steps S1 to S4 according to the number of cycles, and using the dentition finite element model obtained in step S4 of the previous cycle as the dentition finite element model in step S1 of the new cycle; after the cycle ends, the final obtained dentition finite element model is used as the simulation result corresponding to the treatment duration. By replacing the simulation result after the treatment duration with simulations of multiple consecutive unit times, and the initial state of the simulation in each unit time is the result of the previous simulation, and predicting the state of the periodontal ligament and teeth based on the cycle of "initial periodontal ligament stress - alveolar bone reconstruction - periodontal ligament stress release", the method closely matches the actual orthodontic process and improves the accuracy of orthodontic result prediction.

[0018] Preferably, step S4 further includes periodontal ligament stress release on the generated simulated dental arch model.

[0019] Preferably, the periodontal ligament stress relief includes: applying boundary constraints to keep the teeth stationary, releasing the displacement constraints on the periodontal ligament, allowing the periodontal ligament to spring back to a stress-free state, and using this state as the initial state for the next cycle.

[0020] This application embodiment also provides a method for determining a treatment plan. The method generates a post-orthodontic dentition model according to any of the above-mentioned simulation methods based on the orthodontic process. It determines whether the difference between the tooth movement amount in the post-orthodontic dentition model and the designed target movement amount is within a threshold range. If it is not within the threshold range, the treatment plan is adjusted until the difference between the tooth movement amount in the post-orthodontic dentition model and the designed target movement amount is within the threshold range.

[0021] Preferably, when a shell-shaped orthodontic appliance is used, the adjustment of the orthodontic plan includes adjusting at least one of the following: the tooth stage position, attachment shape, attachment position, attachment posture, shell thickness, and selected material corresponding to the shell-shaped orthodontic appliance.

[0022] This application also provides an electronic device, including: 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 a simulation method of the orthodontic process described in any one of the above, or a method for determining a treatment plan as described in any one of the above.

[0023] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the simulation method for the orthodontic process described in any one of the above-described methods, or the method for determining the treatment plan described in any one of the above-described methods.

[0024] The simulation method for the orthodontic process in various embodiments of this invention obtains periodontal ligament stress through finite element analysis and obtains alveolar bone movement through a pre-set relationship function between the unit reconstruction amount of alveolar bone and periodontal ligament stress. Furthermore, the simulation process in this invention does not require the generation of an alveolar bone model. The alveolar bone reconstruction process during orthodontic treatment can be simulated by the movement of the lateral points of the periodontal ligament and the set relationship function. This simplifies the model simulation process while ensuring simulation accuracy. Moreover, the simulation of alveolar bone calculated using periodontal ligament stress can more accurately simulate tooth movement during orthodontic treatment, further enabling the design scheme to better fit the actual orthodontic process. Attached Figure Description

[0025] 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.

[0026] Figure 1 This is a schematic diagram of the wearing method for simulating the orthodontic process of occlusion adjustment in some embodiments of this application;

[0027] Figure 2 This is a schematic diagram of the finite element mesh model of the teeth row in some embodiments of this application;

[0028] Figure 3 This is a schematic diagram of the wearing method for simulating the orthodontic process of occlusion adjustment in other embodiments of this application;

[0029] Figure 4 This is a flowchart of alveolar bone reconstruction based on the amount of alveolar bone reconstruction according to an embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the finite element mesh model of teeth in some embodiments of this application;

[0031] Figure 6 This is a schematic diagram of the finite element mesh model of the teeth row in some embodiments of this application;

[0032] Figure 7 This is a schematic diagram of the finite element mesh model of teeth assembled with accessories in some embodiments of this application;

[0033] Figure 8This is a schematic diagram of the finite element mesh model of the shell-shaped orthodontic appliance in some embodiments of this application;

[0034] Figure 9 This is a schematic diagram of the assembly of a virtual bracket using a finite element mesh model of a tooth row in other embodiments of this application;

[0035] Figure 10 This is a schematic diagram of a simulation device for an orthodontic process according to another embodiment of the present invention;

[0036] Figure 11 This is a schematic diagram of an electronic device structure according to another embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of this application to enable readers to better understand 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 the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0038] One embodiment of the present invention relates to a simulation method for the orthodontic process, comprising: obtaining a finite element mesh model of the dentition, wherein the finite element mesh model of the dentition includes finite element mesh models of teeth and periodontal ligaments; applying orthodontic loads to the teeth in the finite element model of the dentition, obtaining the initial movement of the teeth and the stress of the periodontal ligament; obtaining a relationship function between the unit reconstruction amount of alveolar bone and the stress of the periodontal ligament, calculating the alveolar bone reconstruction amount and reconstruction direction per unit time based on the relationship function and the stress of the periodontal ligament obtained in the previous step; and generating a simulated dentition model based on the initial movement amount, the alveolar bone reconstruction amount, and the reconstruction direction. This provides a more comprehensive understanding of the actual orthodontic effect of the orthodontic appliance model, making the judgment of the orthodontic effect of the orthodontic appliance model more accurate. The following is a detailed description of the implementation details of the shell-shaped orthodontic appliance expression rate calculation method of this embodiment. The following content is only for the convenience of understanding and is not necessary for implementing this solution.

[0039] like Figure 1 As shown, in step S1, a finite element mesh model of the dental arch is obtained, wherein the finite element mesh model of the dental arch includes finite element mesh models of teeth and periodontal ligaments.

[0040] Specifically, when acquiring the finite element mesh model of the dental arch, the processor first acquires the finite element mesh model of the patient's dental arch based on the patient's dental information by generating it in real time or reading externally imported data. The finite element mesh model of the dental arch may contain finite element models of multiple teeth of the patient and finite element models of the periodontal ligament covering the teeth.

[0041] In one example, refer to Figure 2 As shown, tooth model data can be obtained by scanning the teeth using methods such as X-ray, CBCT, MRI, or laser scanning to obtain a tooth geometric model 1, which is then meshed. Alternatively, a standard digital tooth model can be used. The periodontal ligament model 2 can be obtained through MRI or by stretching the tooth to a certain thickness based on the geometric information of the gingival line and root in the tooth model, and then meshed.

[0042] Specifically, when creating a finite element model based on a patient's oral cavity scan data, the tooth model can be constructed using cone-beam computed tomography (CBCT) to obtain the CBCT results. Then, based on the CBCT results and a pre-defined reconstruction algorithm, a 3D reverse reconstruction is performed on the computer, generating a digital model of the patient's teeth. This digital model is then meshed to complete the construction of the tooth portion within the finite element model. Next, using a pre-defined stacking algorithm, the meshes on the meshed tooth surface are stacked along the outward normal direction to form a digital model of the periodontal ligament surrounding the teeth. This is followed by further meshing to complete the construction of the periodontal ligament portion within the finite element model. By performing CBCT on the teeth and then performing 3D reverse reconstruction based on the scan results, the accuracy of the resulting digital tooth model is ensured. Stacking along the outward normal direction further improves the accuracy of the acquired periodontal ligament digital model, thereby enhancing the fit between the finite element model and the patient's actual condition.

[0043] Furthermore, the material properties of the periodontal ligament in the finite element model are determined based on a viscoelastic constitutive model or a hyperelastic constitutive model. Specifically, the finite element model mainly includes three elements: a mesh model, material properties, and constraints and loading conditions. To ensure the consistency between the changes in the finite element model during simulation and the actual orthodontic process, appropriate material properties, constraints, and loading conditions need to be set for each mesh model in the finite element model. The material properties of the tooth mesh model can include the elastic modulus and Poisson's ratio of the tooth; the material properties of the periodontal ligament are determined based on a viscoelastic constitutive model or a hyperelastic constitutive model, so that the periodontal ligament mesh model can closely resemble the actual biological stress mechanism of the periodontal ligament. The elastic modulus and Poisson's ratio of the tooth, and the specific material properties of the periodontal ligament, can be calculated by inputting the constituent data into the corresponding model or obtained by consulting relevant literature resources, which will not be elaborated here.

[0044] To better reflect reality, the constraints on teeth can be set as follows: in the finite element mesh model of the dental arch, the nodes on the side of the tooth root adjacent to the periodontal ligament and the nodes on the side of the periodontal ligament adjacent to the tooth root are bound together; the constraints on the periodontal ligament can be set as follows: the outer surface of the periodontal ligament is fixed during the instantaneous phase of the application of orthodontic force, is subjected to the corresponding reconstruction displacement load during the alveolar bone reconstruction phase, and is in a free state during the periodontal ligament stress release phase.

[0045] In step S2, orthodontic loads are applied to the teeth in the finite element model of the dental arch to obtain the initial movement of the teeth and the stress of the periodontal ligament.

[0046] Specifically, the computer applies orthodontic forces to the tooth mesh model within the finite element model based on the pre-defined loading conditions used during finite element model construction or instructions input by the administrator. Since the tooth experiences a noticeable instantaneous movement—the initial movement—at the moment the orthodontic force is applied, the periodontal ligament outer nodes are constrained according to the constraint conditions while the orthodontic force is applied, and the stiffness matrix of each mesh model is obtained. Then, based on the material properties of each mesh model, the equilibrium differential equations of each mesh model are calculated using the finite element model to obtain the displacement of each node, thereby calculating the instantaneous displacement of the tooth under the orthodontic force and the stress of the periodontal ligament outer nodes under the orthodontic force. For example, a three-dimensional spatial coordinate system is established to obtain the instantaneous displacement of the tooth in this system, and several stress components of the periodontal ligament along different directions within the three-dimensional spatial coordinate system are obtained.

[0047] In step S3, the relationship function between the unit reconstruction amount of alveolar bone and the periodontal ligament stress is obtained. Based on the relationship function and the periodontal ligament stress obtained in step S2, the alveolar bone reconstruction amount and reconstruction direction per unit time are calculated. The alveolar bone reconstruction direction is determined by the displacement direction of the node.

[0048] Specifically, in the relationship function between alveolar bone remodeling volume and periodontal ligament stress, periodontal ligament stress can be either principal stress or hydrostatic pressure. Using either principal stress or hydrostatic pressure as the periodontal ligament stress makes it easier to calculate alveolar bone remodeling volume.

[0049] In one embodiment, when the periodontal ligament stress is hydrostatic pressure, obtaining the functional relationship between the alveolar bone unit reconstruction volume and the periodontal ligament stress includes: obtaining the hydrostatic pressure of each periodontal ligament node in the initial dentition model; calculating the average hydrostatic pressure of the target periodontal ligament node based on the hydrostatic pressure of the target periodontal ligament node and its adjacent periodontal ligament nodes; and when the average hydrostatic pressure is greater than a first preset threshold, obtaining the alveolar bone unit reconstruction volume using the first preset threshold, the average hydrostatic pressure, the number of reconstruction cycles, and the reconstruction cycle. This method allows for a more accurate calculation of the alveolar bone unit reconstruction volume from the hydrostatic pressure.

[0050] In one example, the instantaneous orthodontic load can first be calculated, including applying orthodontic forces to the teeth to constrain the outer nodes of the periodontal ligament, followed by calculating the instantaneous tooth movement and the stress on the periodontal ligament. The stress comprises six components in different directions: σ xx ,σ yy ,σ zz ,σ xy ,σ xz ,σ yz After obtaining the stresses in six directions, the hydrostatic pressure at the periodontal ligament node can be calculated using the following formula.

[0051]

[0052] Hydrostatic pressure reflects the blood supply within the periodontal ligament and can influence alveolar bone remodeling. Since each periodontal ligament node has adjacent units, to obtain accurate hydrostatic pressure at each node, it is necessary to calculate the average hydrostatic pressure at each node. Then, the hydrostatic pressure threshold within the periodontal ligament is introduced. Mean hydrostatic pressure at the nodes of the periodontal ligament Greater than During this process, alveolar bone remodeling occurs, meaning that the periodontal ligament nodes generate a new displacement Δd. The specific calculation of the new displacement generated by the periodontal ligament nodes is shown in the following formula.

[0053]

[0054] Where: a and b are parameters, which are obtained by calculating the hydrostatic pressure on the periodontal ligament of the tooth under different loads and fitting it with clinical data (such as least squares fitting). For example, if the unit time is one day, then the values ​​of a and b are obtained from one day of clinical data.

[0055] Specifically, besides hydrostatic pressure, alveolar bone remodeling volume can also be obtained through principal stress. When periodontal ligament stress is the principal stress, obtaining the functional relationship between alveolar bone remodeling volume per unit and periodontal ligament stress involves: obtaining the principal stress of each periodontal ligament node in the initial dentition model; calculating the average principal stress of the target periodontal ligament node based on its principal stress and that of its adjacent nodes; and when the average principal stress exceeds a second preset threshold, obtaining the alveolar bone remodeling volume per unit using the second preset threshold, average principal stress, number of remodeling cycles, and remodeling cycle. This method allows for a more accurate calculation of alveolar bone remodeling volume per unit from principal stress.

[0056] In one example, the principal stress takes into account the shear stress within the periodontal ligament. In a motion mode dominated by torsion, the principal stress better reflects the stress state within the periodontal ligament. The calculation of the principal stress can be found in classical mechanics textbooks, as detailed in the following formulas:

[0057]

[0058]

[0059]

[0060] Formula (1) is the formula for calculating the principal stress, and formulas (2) and (3) are the formulas for calculating the parameters in formula (1). The principal stress can be calculated using the above formulas. Where (i = 1, 2, 3 correspond to the three principal stresses, and e represents the principal stress at the node of the element), after obtaining the principal stress of the periodontal ligament node, the arithmetic mean of the principal stresses of the shared periodontal ligament nodes on adjacent elements needs to be calculated to obtain the average principal stress of the periodontal ligament node. Where m is the number of units sharing a node.

[0061] After obtaining the average principal stress of the aforementioned periodontal ligament nodes, a structure is constructed based on the principal stress threshold. The function relating the displacement to the mean principal stress is used as a reference.

[0062]

[0063] Where: a and b are parameters, which are obtained by calculating the average principal stress on the periodontal ligament of the tooth under different loads and fitting it with clinical data (such as least squares fitting). For example, if the unit time is one day, then the values ​​of a and b are obtained from one day of clinical data.

[0064] Based on the above formula, the displacement of the outer node of the periodontal ligament when the average principal stress is used as the criterion is Δd. i The direction of movement is consistent with the direction of the principal stresses, and the calculation of the three principal directions is as follows:

[0065]

[0066]

[0067]

[0068] in:

[0069] A i =τ xy τ yz -(σ y -σ i )τ zx

[0070] B i =τ xy τ zx -(σ x -σ i )τ yz

[0071]

[0072] The above formula allows for accurate calculation of the unit remodeling volume of alveolar bone from the principal stress.

[0073] In step S4, a simulated dental arch model is generated based on the initial movement amount, the alveolar bone reconstruction amount, and the reconstruction direction.

[0074] Specifically, in one implementation, the alveolar bone reconstruction amount calculated in step S3 is applied as a displacement loading condition to the periodontal ligament surface nodes in the deformed dentition finite element model obtained in step S2 using finite element analysis software. The simulated dentition model is then calculated based on the reconstruction direction. The finite element model is updated using parameters such as the alveolar bone reconstruction direction, the amount of alveolar bone reconstruction, and the initial displacement to obtain the simulation results of orthodontic treatment per unit time. This fully considers the influence of periodontal ligament stress, a biomechanical process, on orthodontic treatment, making the simulation results more consistent with reality and improving the effectiveness of orthodontic appliances designed based on the simulation results and the accuracy of treatment plans.

[0075] In this embodiment, a finite element model including teeth and periodontal ligament is constructed, and periodontal ligament stress is used as the stimulus condition for orthodontic movement. This ensures that the physiological characteristics and changes that may occur at various locations in the oral cavity under biomechanical mechanisms are fully considered during the orthodontic simulation process, thereby obtaining more accurate orthodontic simulation results. This makes the orthodontic simulation as close to reality as possible, improving the accuracy of the simulation results. It can also provide a scientific reference for the design and evaluation of orthodontic appliances and treatment plans.

[0076] The simulation method flow of the orthodontic process in another embodiment of this application can be referred to. Figure 3 The simulation method for the orthodontic process further includes: Step S5: Obtain the treatment duration, determine the number of cycles based on the treatment duration and the unit time; repeat steps S1 to S4 according to the number of cycles, and use the finite element model of the dentition obtained in step S4 of the previous cycle as the finite element model of the dentition in step S1 of the new cycle; Judgment step S6: When the number of cycles is less than the number of cycles, repeat steps S1 to S4 until the number of cycles equals the number of cycles, and the cycle ends. In step S7, the obtained finite element model of the dentition is used as the simulation result corresponding to the treatment duration, that is, the simulated dentition model generated in the last cycle is the final simulation result. By replacing the simulation result after the treatment duration with simulations of multiple consecutive unit times, and the initial state of the simulation in each unit time is the result of the previous simulation, and predicting the state of the periodontal ligament and teeth based on the cycle of "initial periodontal ligament stress - alveolar bone reconstruction - periodontal ligament stress release", the method closely matches the actual orthodontic process and improves the accuracy of the prediction of orthodontic results.

[0077] Specifically, after obtaining the amount of alveolar bone reconstructed per unit time, it is necessary to reconstruct the alveolar bone throughout the entire process, including: cyclically reconstructing the alveolar bone model within the treatment duration during each reconstruction cycle until the end of the reconstruction cycle; obtaining the simulation results corresponding to the treatment duration based on the final reconstructed alveolar bone model; and releasing periodontal ligament stress and obtaining the reconstructed alveolar bone model within each unit time after reconstruction. Cyclic reconstruction yields alveolar bone models for each reconstruction cycle, facilitating more precise adjustments to the treatment plan based on these models.

[0078] In one example, the specific cyclic reconstruction process is as follows: Figure 4 As shown. Each time, the calculated alveolar bone reconstruction per unit time is applied as a displacement load to the outer nodes of the periodontal ligament, and the deformed mesh model and stress results are calculated. In some embodiments, the generated simulated dentition model undergoes periodontal ligament stress release. Specifically, boundary constraints are applied to keep the teeth stationary, the displacement constraints on the periodontal ligament are released, allowing the periodontal ligament to spring back to a stress-free state, and this state is used as the initial state for the next cycle. Thus, the simulation of a single cycle (which can be one day or one week) of orthodontic treatment is completed. Finally, within the treatment duration, the single reconstruction process is repeated. For example, if the unit time of one cycle is one week and the treatment duration is two weeks, then two cycles of alveolar bone reconstruction are required within two weeks. The treatment duration and unit time in the above embodiments are only examples and are not intended to limit the scope of protection of this application.

[0079] The steps described above are for clarity only. In practice, they can be combined into one step or some steps can be broken down 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.

[0080] Another embodiment of the present invention relates to a method for determining a treatment plan. This method generates a post-orthodontic dentition model based on a simulation method of the orthodontic process. It then determines whether the difference between the tooth movement in the post-orthodontic dentition model and the designed target movement is within a threshold range. If the difference is not within the threshold range, the treatment plan is adjusted until the difference between the tooth movement in the post-orthodontic dentition model and the designed target movement is within the threshold range. Specifically, the inventors of this application determine, based on clinical experience and literature review, that if the tooth movement accounts for 50%-100% of the designed target movement, the treatment plan is considered to meet the condition.

[0081] In one implementation, when a shell-shaped orthodontic appliance is used, adjustments are made to the design of the shell-shaped appliance, including adjusting at least one of the following: the tooth stage position corresponding to the shell-shaped appliance, the shape of the attachments, the position of the attachments, the posture of the attachments, the shell thickness, and the selected material. By adjusting different parameters of the appliance, it can be made suitable for more orthodontic treatment programs, thus broadening its application range.

[0082] In one example, refer to Figure 5 As shown, maxillary tooth 11 (tooth 3) was selected as the target tooth for study. The tooth's geometric model is as follows: Figure 6 As shown, the treatment goal is to achieve a controlled distal movement of the target tooth of 0.15 mm, which is the designed movement amount. Periodontal ligament model 2 is obtained by selecting the portion below the gingival line of the above tooth model and stretching it 0.25 mm outwards. The tooth and periodontal ligament models are shown below. Figure 6 As shown.

[0083] In this embodiment, a shell-shaped orthodontic appliance is used for correction, and the correction scheme is as follows: Figure 7 As shown, a shell-shaped orthodontic appliance model 5 is used with two attachments on 11 teeth. Figure 8 As shown, it can be obtained through a target dental model or by scanning. The shell-shaped orthodontic appliance model can be a shell without thickness or a shell with thickness.

[0084] Orthodontic load was obtained by simulating the initial wearing of the shell-shaped appliance. The shell-shaped appliance model was placed on the corresponding periodontal ligament finite element model. The appliance, attachments, and teeth were modeled using linear elasticity, with elastic moduli of 900–1300 MPa, 700–1400 MPa, and 13000–20000 MPa, and Poisson's ratios of 0.25–0.35, respectively. The periodontal ligament was modeled using linear elasticity with an elastic modulus of 40–80 MPa and a Poisson's ratio of 0.45–0.49. The displacement of the outer nodes of the periodontal ligament was constrained. The initial wearing process was simulated through the interference fit between the appliance, teeth, and attachments. The new position, stress on the periodontal ligament, and initial displacement were calculated. Then, the new 11... The model of tooth #11 and periodontal ligament is used. The stress of the outer nodes of the periodontal ligament is incorporated into the relationship function between the unit reconstruction amount of alveolar bone and the periodontal ligament stress in step S3. For example, it could be the relationship function between the unit reconstruction amount of alveolar bone and the hydrostatic pressure of the periodontal ligament. The movement amount and direction of the outer nodes of the periodontal ligament are obtained as the displacement loading conditions in the second step. The new position and morphology of tooth #11 and periodontal ligament are calculated, that is, tooth #11 and periodontal ligament after alveolar bone reconstruction per unit time. The reconstructed tooth and periodontal ligament are then re-imported into the initial wearing simulation model to replace the original tooth #11 and periodontal ligament. The initial wearing and alveolar bone reconstruction simulation is repeated to obtain the position of tooth #11 after n unit times. Compared with the designed movement amount, if the percentage of tooth movement to the designed target movement amount is less than 50%, the designed movement amount of tooth #11 or the attachment usage type in the orthodontic plan is adjusted, and the simulation is repeated until the percentage of tooth movement to the designed target movement amount is between 50% and 100%. The current orthodontic plan is then confirmed as the correct one.

[0085] In another example, maxillary premolar 11 (tooth 3) is also used as the target tooth in the study. The treatment goal is to achieve a controlled distal movement of 0.15 mm, which is the designed movement amount. In this embodiment, reference is made to... Figure 9 As shown, fixed bracket 6 is used to orthodontically treat the teeth.

[0086] Orthodontic loads are applied to the designed positions of the brackets on the teeth. The teeth are modeled using a linear elastic modulus with elastic moduli of 900–1300 MPa, 700–1400 MPa, and 13000–20000 MPa, and Poisson's ratios ranging from 0.25 to 0.35. The periodontal ligament is modeled using a linear elastic modulus of 40–80 MPa and a Poisson's ratio of 0.45–0.49. The displacement of the outer nodes of the periodontal ligament is constrained. The new positions of the teeth and the stress and initial displacement of the periodontal ligament under orthodontic loads are calculated. Then, a new model of tooth number 11 and the periodontal ligament is extracted, and the stresses of the outer nodes of the periodontal ligament are transferred to the step... In step S3, the relationship function between the unit amount of alveolar bone reconstruction and the periodontal ligament stress (e.g., the relationship function between the unit amount of alveolar bone reconstruction and the hydrostatic pressure of the periodontal ligament) is used to obtain the movement amount and direction of the outer node of the periodontal ligament. This serves as the displacement loading condition in the second step. The new position and morphology of tooth 11 and the periodontal ligament are calculated, i.e., tooth 11 and the periodontal ligament after alveolar bone reconstruction per unit time. The reconstructed tooth and periodontal ligament are then re-imported into the initial wearing simulation model to replace the original tooth 11 and periodontal ligament. Repeating the initial wearing and alveolar bone reconstruction simulation yields the position of tooth 11 after n unit times. Compared with the designed movement amount, if the percentage of tooth movement to the designed target movement amount is less than 50%, the designed movement amount of tooth 11, the bracket position, or the orthodontic load in the treatment plan is adjusted. The simulation is repeated until the percentage of tooth movement to the designed target movement amount is between 50% and 100%, confirming the current treatment plan as the correct one.

[0087] It is not difficult to see that this embodiment is a device embodiment corresponding to the above method embodiment, and this embodiment can be implemented in conjunction with the above method embodiment. The relevant technical details mentioned in the above method embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the above method embodiment.

[0088] Another embodiment of the present invention relates to a simulation device for the orthodontic process, a schematic diagram of which is shown below. Figure 10 As shown, it includes: an acquisition module and a calculation module; the acquisition module obtains a finite element mesh model of the dental arch, the orthodontic load applied to the teeth in the finite element model of the dental arch, and the relationship function between the unit reconstruction amount of alveolar bone and the periodontal ligament stress; the calculation module is used to calculate the initial movement of the teeth and the periodontal ligament stress under the orthodontic load applied to the teeth in the finite element model of the dental arch, and uses the relationship function between the unit reconstruction amount of alveolar bone and the periodontal ligament stress and the periodontal ligament stress obtained in the previous step to calculate the alveolar bone reconstruction amount and reconstruction direction per unit time; finally, a simulated dental arch model is generated based on the initial movement amount, the alveolar bone reconstruction amount, and the reconstruction direction.

[0089] It is worth mentioning that all modules involved in this embodiment are logical modules. In practical applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. Furthermore, to highlight the innovative aspects of this invention, this embodiment does not introduce units that are not closely related to solving the technical problem proposed by this invention; however, this does not mean that other units are absent from this embodiment.

[0090] Another embodiment of the present invention relates to an electronic device, the schematic diagram of which is shown below. Figure 11 As shown, it includes: 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 a simulation method of the orthodontic process as described above, or a method for determining a treatment plan as described above.

[0091] 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.

[0092] 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.

[0093] Another 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 embodiments.

[0094] 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.

[0095] 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 for simulating the orthodontic process, characterized in that, include: Step S1: Obtain the finite element mesh model of the dental arch, wherein the finite element mesh model of the dental arch includes the finite element mesh models of teeth and periodontal ligament; Step S2: Apply orthodontic load to the teeth in the finite element model of the dental arch to obtain the initial movement of the teeth and the stress of the periodontal ligament; Step S3: Obtain the relationship function between alveolar bone unit reconstruction amount and periodontal ligament stress, and calculate the alveolar bone reconstruction amount and reconstruction direction per unit time based on the relationship function and the periodontal ligament stress obtained in step S2. Step S4: Generate a simulated dental arch model based on the initial movement amount, the alveolar bone reconstruction amount, and the reconstruction direction.

2. The method for simulating the orthodontic process according to claim 1, characterized in that, In the finite element mesh model of the dental arch, the nodes on the side of the tooth root adjacent to the periodontal ligament and the nodes on the side of the periodontal ligament adjacent to the tooth root are bound together.

3. The method for simulating the orthodontic process according to claim 1, characterized in that, Step S2 also includes: obtaining the finite element model of the dental arch after deformation under the instantaneous application of orthodontic load.

4. The method for simulating the orthodontic process according to claim 3, characterized in that, Step S4 includes: applying the alveolar bone reconstruction amount calculated in step S3 as a displacement loading condition to the periodontal ligament surface nodes in the deformed dentition finite element model obtained in step S2, and calculating the simulated dentition model according to the reconstruction direction.

5. The method for simulating the orthodontic process according to claim 1, characterized in that, The periodontal ligament stress in the relationship function between the unit reconstruction of alveolar bone and the periodontal ligament stress refers to the principal stress of the periodontal ligament or the hydrostatic pressure of the periodontal ligament.

6. The method for simulating the orthodontic process according to claim 5, characterized in that, Based on the aforementioned relationship function and the periodontal ligament stress obtained in step S2, the amount of alveolar bone remodeling per unit time is calculated. This includes calculating the average hydrostatic pressure of the target periodontal ligament node based on the hydrostatic pressure of the target periodontal ligament node and its adjacent periodontal ligament nodes, and when the average hydrostatic pressure is greater than a first preset threshold, the amount of alveolar bone reconstruction is obtained by using the first preset threshold and the average hydrostatic pressure.

7. The method for simulating the orthodontic process according to claim 5, characterized in that, The calculation of alveolar bone remodeling per unit time based on the functional relationship and the stress of the periodontal ligament includes calculating the average principal stress of the target periodontal ligament node based on the principal stress of the target periodontal ligament node and its adjacent periodontal ligament nodes. When the average principal stress is greater than the second preset threshold, the amount of alveolar bone reconstruction is obtained by the preset second preset threshold and the average principal stress.

8. The method for simulating the orthodontic process according to claim 1, characterized in that, It also includes: Step S5: Obtain the treatment duration, and determine the number of cycles based on the treatment duration and the unit time; The steps S1 to S4 are repeated according to the number of cycles, and the finite element model of the dental arch obtained in step S4 of the previous cycle is used as the finite element model of the dental arch in step S1 of the new cycle. After the loop ends, the final finite element model of the dental arch is used as the simulation result corresponding to the treatment duration.

9. The method for simulating the orthodontic process according to claim 8, characterized in that, Step S4 also includes periodontal ligament stress release on the generated simulated dental arch model.

10. The method for simulating the orthodontic process according to claim 9, characterized in that, The periodontal ligament stress relief includes: applying boundary constraints to keep the teeth stationary, releasing the displacement constraints on the periodontal ligament, allowing the periodontal ligament to spring back to a stress-free state, and using this state as the initial state for the next cycle.

11. A method for determining a treatment plan, characterized in that, The method based on the simulation process of orthodontic treatment according to any one of claims 1-10 generates a dental arch model after orthodontic treatment, determines whether the difference between the tooth movement amount in the dental arch model after orthodontic treatment and the designed target movement amount is within a threshold range, and adjusts the treatment plan until the difference between the tooth movement amount in the dental arch model after orthodontic treatment and the designed target movement amount is within the threshold range.

12. The method for determining the corrective treatment plan according to claim 11, characterized in that, When a shell-shaped appliance is used, the adjustment of the treatment plan includes adjusting at least one of the following: the tooth stage position, attachment shape, attachment position, attachment posture, shell thickness, and selected material corresponding to the shell-shaped appliance.

13. An electronic device, characterized in that, include: At least one processor; as well as, 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 a simulation method of the orthodontic process according to any one of claims 1 to 10, or a method for determining a treatment plan according to any one of claims 11-12.

14. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the simulation method of the orthodontic process according to any one of claims 1 to 10, or the method for determining the treatment plan according to any one of claims 11 to 12.

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