Dynamic simulation method and system for tooth movement process based on Type model

Abstract

The invention relates to a dynamic simulation method and system for a tooth movement process based on a Type model, and the method comprises the steps: carrying out the data collection of an artificial tooth and a fixed appliance through three-dimensional scanning, and obtaining the three-dimensional data of a tooth jaw structure; performing overlap analysis on the crown root model according to the three-dimensional data to obtain a digital dental model containing periodontal tissues; performing material attribute assignment on an anatomical structure in the digital tooth jaw model according to preset material parameters to obtain a biomechanical tooth jaw model; and performing time recursion iteration on the biomechanical tooth jaw model through finite element analysis to obtain four-dimensional dynamic simulation data for simulating a tooth movement process, so as to provide visual orthodontic process teaching demonstration based on the four-dimensional dynamic simulation data. According to the invention, the dynamic visual simulation of the tooth movement process is realized, the feedback of the Type Dont system can be quantified, and the teaching interactivity is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of orthodontic technology, and in particular to a dynamic simulation method and system for tooth movement process based on a Typodont model. BACKGROUND

[0002] A Typodont model is an important tool for orthodontic teaching. In order to help orthodontic beginners to intuitively understand the principles of correction mechanics and improve the operation precision, the traditional Typodont training adopts the method of bonding brackets on the model, placing the arch wire, and using water bath heating wax type to simulate the movement of teeth under the action of the elastic arch wire, so as to provide preclinical skill training for medical students, thereby improving their understanding of biomechanics and operation precision.

[0003] For the existing Typodont model, the Typodont before and after the experiment is digitally processed by combining three-dimensional scanning and reverse engineering technology, and the tooth model is superimposed and matched in the software to establish a three-dimensional model of the dentition with tooth roots. Subsequently, taking the rigid base of the model as the reference, the initial model and the end model are overlapped in the Geomagic software, the displacement of each landmark point is marked and measured, the three-dimensional movement of the teeth is quantitatively analyzed, and reference is provided for clinical application.

[0004] However, the three-dimensional model of the dentition obtained by the above method can only present the static results of two time nodes, and cannot reflect the dynamic changes of the teeth during the correction process, nor can it simulate the real environment in the mouth such as the periodontal membrane. SUMMARY

[0005] The present application provides a dynamic simulation method and system for tooth movement process based on a Typodont model to solve the defects of the prior art.

[0006] The present application provides a dynamic simulation method for tooth movement process based on a Typodont model, comprising: S1: acquiring data of artificial teeth and fixed orthodontic appliances by three-dimensional scanning to obtain three-dimensional data of the dental arch structure; S2: performing overlap analysis on the crown-root model according to the three-dimensional data to obtain a digitalized dental arch model containing periodontal tissue; S3: assigning material properties to the anatomical structures in the digitalized dental arch model according to the preset material parameters to obtain a biomechanical dental arch model; S4: performing time recursion iteration on the biomechanical dental arch model by finite element analysis to obtain four-dimensional dynamic simulation data simulating the tooth movement process, and providing visual orthodontic process teaching demonstration based on the four-dimensional dynamic simulation data.

[0007] The application provides a dynamic simulation method of tooth movement based on a Typodont model, wherein the three-dimensional data in step S1 is collected by a first collection method or a second collection method.

[0008] The application provides a dynamic simulation method of tooth movement based on a Typodont model, and the first collection method further comprises the following steps. S111: scanning artificial teeth by a three-dimensional scanner to obtain a tooth STL model; S112: placing the artificial teeth in a standard wax ridge to perform full dentition scanning to obtain three-dimensional data of complete dentition; S113: collecting original digital files of different types of brackets and arch wires to obtain three-dimensional structure data of fixed appliances.

[0009] The application provides a dynamic simulation method of tooth movement based on a Typodont model, and the second collection method further comprises the following steps. S121: scanning a subject by a cone beam CT to obtain original tomographic data containing soft and hard tissue information; S122: scanning dentition of the subject by an intraoral scanner to obtain surface information of a digitalized dental model; S123: scanning different specifications of appliances by a three-dimensional scanner to obtain three-dimensional data of straight wire bracket, edgewise bracket and arch wires of different sizes.

[0010] The application provides a dynamic simulation method of tooth movement based on a Typodont model, and step S2 further comprises the following steps. S21: aligning tooth models at different stages at a crown by Geomagic software to obtain a three-dimensional spatial position relationship of the crown; S22: establishing a spatial position of a tooth root structure according to the three-dimensional spatial position relationship to obtain a tooth model; S23: adding periodontal tissue structure data to the tooth model to obtain a digitalized dental model containing a periodontal membrane, a gum and a maxillofacial bone.

[0011] The application provides a dynamic simulation method of tooth movement based on a Typodont model, and step S3 specifically comprises the following steps. linear elasticity and isotropic material properties are assigned to alveolar bone and teeth to obtain a first mechanical property model of hard tissue; homogeneous material properties are assigned to a gum and a periodontal membrane to obtain a second mechanical property model of soft tissue; The material attribute of different specifications of brackets and arch wires is assigned to obtain a third mechanical property model of the appliance.

[0012] According to the dynamic simulation method of the tooth movement process based on the Typodont model, the elastic modulus of the periodontal membrane is assigned as 0.5-1.5 MPa, and the Poisson ratio is assigned as 0.45. According to the dynamic simulation method of the tooth movement process based on the Typodont model, the elastic modulus of the periodontal membrane is assigned as 0.5-1.5 MPa, and the Poisson ratio is assigned as 0.45. According to the dynamic simulation method of the tooth movement process based on the Typodont model, the elastic modulus of the periodontal membrane is assigned as 0.5-1.5 MPa, and the Poisson ratio is assigned as 0.45. According to the dynamic simulation method of the tooth movement process based on the Typodont model, the elastic modulus of the periodontal membrane is assigned as 0.5-1.5 MPa, and the Poisson ratio is assigned as 0.45. According to the dynamic simulation method of the tooth movement process based on the Typodont model, the elastic modulus of the periodontal membrane is assigned as 0.5-1.5 MPa, and the Poisson ratio is assigned as 0.45.

[0013] According to the dynamic simulation method of the tooth movement process based on the Typodont model, the elastic modulus of the periodontal membrane is assigned as 0.5-1.5 MPa, and the Poisson ratio is assigned as 0.45. S41: setting a fixed constraint condition of the upper and lower jaws to obtain a model reference; S42: obtaining a model force transmission mechanism by setting a fixed contact between the teeth and the bracket and a sliding contact with a gap between the bracket and the arch wire; S43: obtaining load distribution data of multiple parts of the dentition by simulating the process of the arch wire recovering from the initial bending state to the straight state; S44: establishing a dynamic simulation model based on the model reference, the model force transmission mechanism and the load distribution data; S45: simulating the teeth to be simulated through the dynamic simulation model, and outputting four-dimensional dynamic simulation data of the simulated tooth movement process.

[0014] According to the dynamic simulation method of the tooth movement process based on the Typodont model, the elastic modulus of the periodontal membrane is assigned as 0.5-1.5 MPa, and the Poisson ratio is assigned as 0.45. S441: obtaining tooth movement data by applying orthodontic force through elastic deformation of the arch wire and calculating initial displacement of the teeth under stress; S442: updating the geometry of the alveolar bone according to the tooth movement data to obtain simulation results of bone resorption and reconstruction; S443: synchronously adjusting the geometry of the periodontal membrane by maintaining the constraint condition of the constant periodontal membrane gap to obtain an updated simulation model; S444: cyclically updating the updated simulation model to obtain a dynamic simulation model.

[0015] The application also provides a dynamic simulation system of a tooth movement process based on a Typodont model, comprising: A scanning module is used for collecting data of artificial teeth and fixed appliances through three-dimensional scanning to obtain three-dimensional data of the dental arch structure. an analysis module configured to perform superimposition analysis on the crown-root model according to the three-dimensional data to obtain a digitized dental model containing periodontal tissue; an assignment module configured to assign material properties to anatomical structures in the digitized dental model according to preset material parameters to obtain a biomechanical dental model; a simulation module configured to perform time-propagation iteration on the biomechanical dental model through finite element analysis to obtain four-dimensional dynamic simulation data simulating tooth movement, and to provide visual orthodontic process teaching demonstration based on the four-dimensional dynamic simulation data.

[0016] The dynamic simulation method and system for tooth movement based on the Typodont model provided by the present application constructs a high-precision three-dimensional dental model through digital technology, breaks through the limitations of traditional Typodont physical models, and significantly improves the efficiency and quality of teaching training. Compared with the tedious process of repeatedly heating and cooling required by traditional models, the present application can instantly present the application effect of the appliance, greatly shortening the training period and improving the learning efficiency. Secondly, the present application introduces a simulation system based on real biomechanical parameters, accurately assigns material properties to tissues such as teeth, periodontal membrane and alveolar bone, and constructs a simulation platform that is closer to the real oral environment, making up for the huge gap between traditional wax barrier thermoplasticity and real alveolar bone physiological reconstruction, and making the simulation results more clinically valuable. Thirdly, the present application realizes four-dimensional dynamic simulation of tooth movement through finite element analysis, not only can observe the static results at different time points, but also can dynamically display the continuous changes of tooth movement in the whole treatment process, and the visualization of the whole process greatly enhances the understanding depth of the learners on the orthodontic biomechanical principles, which helps to form a systematic diagnosis and treatment thinking. In addition, the present application can accurately simulate the complex real environment in the mouth, including occlusal force, gum elasticity and periodontal membrane fiber, etc., so that the learners can fully consider the influence of various biomechanical factors on the treatment effect, and avoid the cognitive bias caused by the excessive simplification of traditional models. The present application also establishes a real-time biological feedback mechanism, and the learners can intuitively monitor the changes of the correction force, which helps to accurately control the size and direction of the force, avoids the formation of excessive force and other bad operation habits, reduces the risk of complications such as root resorption and bone windowing in clinical practice, and makes the simulation results more accurate and reliable, providing an objective and quantitative basis for teaching evaluation.

[0017] The present application realizes the standardization and normalization of the teaching process through digital technology, provides a unified operation standard and evaluation system for orthodontic teaching, greatly promotes the overall improvement of teaching quality, at the same time provides a safe and efficient skill training platform for orthodontic beginners, shortens the clinical learning curve, and lays a solid foundation for the teaching of orthodontic profession. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0019] Figure 1 A flowchart of a dynamic simulation method of tooth movement process based on a Typodont model provided by the present application; Figure 2 A structural schematic diagram of a dynamic simulation system of tooth movement process based on a Typodont model provided by the present application. DETAILED DESCRIPTION

[0020] In order to make the objects, technical solutions and advantages of the present application clearer, the following will combine the drawings in the present application to clearly and completely describe the technical solutions in the present application. Obviously, the described embodiments are some embodiments of the present application, not all the embodiments, and they should not be understood as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application. In the description of the present application, it should be understood that the terms used are only for the purpose of description, and should not be understood as indicating or implying relative importance.

[0021] In order to better understand the present application, the following will first explain and describe the research background of the present application in detail.

[0022] Orthodontics is a discipline with both theoretical depth and practical height, and its core is to realize the functional reconstruction of the dental and maxillofacial system through precise biomechanical regulation, and dynamically optimize the treatment process relying on real-time biological feedback mechanism. Fixed orthodontic treatment is the most common orthodontic treatment method. In fixed orthodontic treatment, the position of the bracket, the shape and angle of the arch wire directly determine the movement path of the teeth.

[0023] However, since the fixed appliance will produce a complex force system after activation, the movement path of the teeth is difficult to accurately predict, especially for inexperienced doctors, the long-term clinical operation effect is difficult to grasp, and improper operation may also lead to unexpected tooth movement, and even increase the risk of root resorption, bone fenestration and bone cracking.

[0024] To help orthodontic beginners intuitively understand the principles of treatment mechanics and improve their operation accuracy, traditional Typodont training uses the method of bonding brackets on the model, placing arch wires, and using water bath heating wax to simulate the movement of teeth under the action of elastic arch wires, providing pre-clinical skill training for medical students, thereby improving their understanding of biomechanics and operation accuracy.

[0025] Typodont model is an important tool for orthodontic teaching, which is composed of resin teeth, wax dam and fixed base, and can simulate the structure of dental arch system to provide a highly simulated operation environment for pre-clinical skill training. The teaching process includes three stages: first, install the appliance, such as bracket bonding and arch wire insertion; second, soften the wax dam in the temperature-controlled water bath to simulate the plasticity of alveolar bone and allow tooth movement; finally, observe the tooth displacement after the model is cooled and fixed.

[0026] Typodont has many teaching advantages: it provides a simulated operation environment, highly restores clinical orthodontic operation, allows students to practice basic skills such as bracket bonding and arch wire bending without patient pressure, and reduces the risk of clinical training; it can simulate tooth extraction space closure, expansion treatment and other special cases to help students develop systematic diagnostic and treatment thinking.

[0027] However, the traditional Typodont still has limitations: the operation process is long, the training period is limited; the material properties are different from the real tissue, the thermoplasticity of the wax dam cannot accurately simulate the physiological reconstruction of the alveolar bone, the tooth movement process is simplified, and the biological feedback such as muscle strength and cortical bone anchorage is ignored; it cannot simulate the real environment in the mouth (occlusion force, gum and periodontal membrane fibers, etc.), and it is difficult to reflect the actual biomechanical response in clinical practice; it lacks dynamic feedback mechanism, students cannot monitor the changes of the treatment force in real time, it is difficult to accurately control the force, and even form the habit of overloading; there is no uniform standard for heating time and force application method, if there is no guidance, students may operate mechanically and ignore the thinking of biomechanical principles.

[0028] Existing researches use three-dimensional scanning and reverse engineering technology to digitize the Typodont before and after the experiment, and superimpose the matching tooth model in the software to establish a three-dimensional model of the dental arch with tooth roots. Then, taking the rigid base of the model as the reference, the initial model and the end model are overlapped in Geomagic software, the displacement of each landmark point is marked and measured, and the three-dimensional movement of the teeth is quantitatively analyzed, thereby providing a reference for clinical application. However, this method still has limitations, it can only present the static results of two time nodes, cannot reflect the dynamic changes of teeth during the treatment, and cannot simulate the real environment in the mouth such as periodontal membrane.

[0029] Therefore, the present application provides a dynamic simulation method and system for tooth movement process based on Typodont model.

[0030] Embodiments of the present application will be described below with reference to the accompanying drawings.

[0031] In the present embodiment, the present application provides a dynamic simulation method and system for tooth movement process based on Typodont model, which is used for orthodontic teaching and training to provide visual orthodontic treatment process teaching demonstration for students and doctors.

[0032] It should be noted that the dynamic simulation method and system for tooth movement process based on Typodont model provided by the present application are not limited to specific application fields. The method can truly reproduce the dynamic process of tooth movement by establishing an accurate three-dimensional digital dental model and biomechanical simulation, and has wide application value. It can be applied to the teaching and training of orthodontics to provide students and clinicians with intuitive visual teaching tools, and can also be used for the prediction and optimization of clinical treatment plans, the design verification of orthodontic appliances, the data analysis of scientific experiments, and many other fields. The technical means of the present application is universal and should not be understood as being limited to teaching purposes. Its application scope covers but is not limited to medical education, clinical practice, scientific research and related industrial design.

[0033] As shown in Figure 1 The present application provides a dynamic simulation method for tooth movement process based on Typodont model, comprising: S1: acquiring three-dimensional data of dental arch structure by three-dimensional scanning of artificial teeth and fixed appliances.

[0034] Among them, the three-dimensional data in step S1 is collected by a first collection method or a second collection method.

[0035] Further, the step S1 of the present application first acquires three-dimensional data of dental arch structure by three-dimensional scanning of artificial teeth and fixed appliances, which can be realized by two collection methods, the first collection method and the second collection method. The first collection method is suitable for laboratory standardized environment, and the second collection method is based on clinical patient data and obtains real oral structure information through medical imaging means.

[0036] Among them, the first collection method further comprises: S111: scanning artificial teeth by a three-dimensional scanner to obtain a tooth STL model.

[0037] Further, the STL (Stereolithography) model is a triangular facet mesh model, which represents the object surface shape by triangular patching. In the specific scanning process, the three-dimensional scanner emits structured light or laser, and the reflected signal is received by the CCD sensor to calculate the three-dimensional coordinate point cloud data of the object surface. The obtained point cloud data is processed by noise reduction, filtering and mesh reconstruction, and converted into a triangular mesh model with a clear topological structure. Finally, a high-precision STL model composed of multiple triangular facets is obtained after mesh reconstruction, and each triangular facet is defined by three vertex coordinates and a normal vector to accurately describe the geometric morphology of the tooth surface.

[0038] S112: The artificial tooth is placed in the standard occlusal wax dam for full dentition scanning to obtain three-dimensional data of the complete dentition.

[0039] Further, the standard occlusal wax dam is a basic structure simulating the relationship between the alveolar bone and the occlusion, which is made of special silicone rubber or wax material. The principle of full dentition scanning is the same as that of single tooth scanning, but it requires a larger scanning range and more complex data splicing. The scanning system performs spatial registration on the multiple scanning data through a feature point matching algorithm to generate a complete dentition model in a unified coordinate system. During the process, the accurate position relationship of each tooth and the overall morphological characteristics of the dentition are recorded to provide a basic data framework for subsequent simulation.

[0040] S113: Obtain three-dimensional structure data of fixed appliances by collecting original digitized files of different types of brackets and arch wires.

[0041] In step S113, three-dimensional structure data of fixed appliances is obtained by collecting original digitized files of different types of brackets and arch wires. Orthodontic brackets include straight wire brackets, edgewise brackets and other types, and arch wires have different materials and cross-sectional sizes. The three-dimensional data of these appliances can be collected by high-precision industrial scanners. The collected data includes accurate geometric parameters of the appliances, such as bracket groove size, incidence angle, and torsion angle.

[0042] The second acquisition method further includes: S121: Scan the subject by cone beam CT to obtain original tomographic data containing soft and hard tissue information.

[0043] Cone beam CT (Cone Beam Computed Tomography, CBCT) is a special CT scanning technology that uses a cone-shaped X-ray beam and a two-dimensional detector array to acquire complete three-dimensional data of the patient's head through a single rotation. During CBCT scanning, the X-ray source and detector rotate around the patient's head by about 180-360 degrees, and hundreds of two-dimensional projection images are collected.

[0044] The original projection data is reconstructed into voxel data by a back projection algorithm, each voxel representing the tissue density value in a tiny cube in space. The advantage of CBCT scanning is that the radiation dose is low, and three-dimensional information of hard tissues such as teeth and alveolar bone can be obtained at the same time, providing complete anatomical structure data for subsequent modeling, that is, the contours of teeth and bones can be extracted through gray threshold segmentation.

[0045] S122: scanning the dentition of the subject by the intraoral scanner to obtain surface information of the digital dental model.

[0046] The intraoral scanner can directly perform three-dimensional scanning in the patient's mouth. During scanning, the operator places the scanning head in the patient's mouth and slowly moves along the dentition. The scanning system real-time acquires and splices three-dimensional data. The acquired data is processed by an automatic registration algorithm, and a complete maxillary and mandibular dentition model and occlusion relationship record can be formed. The final obtained surface information has higher surface detail resolution and can accurately reflect the crown morphology and occlusal contact relationship.

[0047] S123: scanning different specifications of the appliance by the three-dimensional scanner to obtain three-dimensional data including straight wire bracket, square wire bracket and different sizes of arch wire.

[0048] The three-dimensional data collected in step S123 of the present application is similar to the first acquisition method, and the purpose is to obtain accurate geometric data of the appliance, which provides a basis for subsequent mechanical simulation. The difference is that in the second acquisition method, specific models of appliances matching clinical treatment need to be scanned to ensure the consistency of the simulation results and the actual treatment effect.

[0049] S2: performing overlap analysis on the crown-root model according to the three-dimensional data to obtain a digital dental model containing periodontal tissue.

[0050] Wherein, step S2 further comprises: S21: aligning the tooth models at the crown part at different stages by Geomagic software to obtain the three-dimensional spatial positional relationship of the crown part.

[0051] In step S21, the crown three-dimensional data obtained in step S1 is first imported into the reverse engineering software Geomagic software, and automatic coarse registration is performed through a global best-fit algorithm (Global Best-Fit Registration), and then fine registration is performed through an iterative closest point algorithm (Iterative Closest Point, ICP). The core principle of the ICP algorithm is to iteratively find the best rigid transformation between two point cloud data sets to minimize the sum of squared Euclidean distances between them. In each iteration, the algorithm first finds the point correspondence between the two point clouds, then calculates the best rigid transformation, updates the position of the source point cloud, and repeats the process until convergence. The alignment accuracy is measured using the root mean square error (RMSE).

[0052] It should be noted that the names of commercial software such as Geomagic software mentioned in the embodiments of the present application are only examples of technical implementation schemes and do not constitute a limitation on the technical solutions of the present application, nor do they have any copyright problems. The core technology of the present application lies in the tooth movement dynamic simulation method based on the Typodont model itself, rather than the use of specific software tools.

[0053] In actual implementation, those skilled in the art can certainly select other equivalent reverse engineering software or three-dimensional modeling software according to specific needs to achieve the same technical effect, such as other products of 3D Systems Company, open source software MeshLab, CloudCompare, or self-developed special software, etc. Therefore, the technical solutions described in the present application have universality and portability, and are not dependent on any specific commercial software. The selection of software tools should not be understood as a limitation on the protection scope of the present application.

[0054] S22: Establishing the spatial position of the tooth root structure according to the three-dimensional spatial position relationship to obtain a dental model.

[0055] Since the tooth root information cannot be obtained by intraoral scanning or conventional dental model scanning, the tooth root information in the CBCT data is integrated with the crown scanning data in step S22, and specifically, a feature point-based registration method is used. First, the complete tooth structure (including the crown and the tooth root) is segmented in the CBCT data, and then the crown in the CBCT is registered with the high-precision crown scanning data aligned in advance by taking the crown part as a reference area. The registration uses a matching algorithm based on surface curvature and anatomical feature points, and the transformation matrix between the two sets of data is calculated through the spatial correspondence of the anatomical landmark points such as the tooth neck line, the highest point of the crown edge, the tooth tip, and the fossa, so as to convert the tooth root data in the CBCT to a unified coordinate system. Since the resolution of the CBCT data is lower than that of the intraoral scanning data, the data fusion of the crown transition zone is also included in step S22. Specifically, the B-spline interpolation method is used to smooth the data splicing boundary of the tooth neck part to ensure the continuity and fidelity of the crown-root transition.

[0056] S23: Adding periodontal tissue structure data to the dental model to obtain a digitized dental arch model including the periodontal membrane, the gum, and the upper and lower jaws.

[0057] Further, in the obtained digitized dental arch model, the periodontal membrane is a fibrous tissue connecting the tooth and the alveolar bone, the width is about 0.25 mm, the gum is a mucous membrane tissue covering the surface of the alveolar bone, and the upper and lower jaws are bony structures supporting the teeth. The models of these tissues are constructed based on CBCT data segmentation and anatomical rules.

[0058] Specifically, first, the bone tissue structure is extracted from the CBCT data by threshold segmentation, and the region growing algorithm and morphological operation are used to optimize the segmentation result to obtain the three-dimensional model of the upper and lower jaws. For the periodontal membrane, since its thickness is lower than the resolution of the CBCT, a computer-aided design method is used to create a uniform-thickness periodontal membrane model by offsetting the tooth root surface by 0.25 mm. The offset operation uses the normal vector extrapolation algorithm to extrapolate a specified distance along the normal vector direction of each vertex of the tooth root surface to generate a new surface model. For the gum tissue, the gum model is constructed by a surface reconstruction algorithm in combination with the soft tissue contour in the CBCT and anatomical rules to ensure a natural transition with the crown and the alveolar bone. In the data processing process, Laplace smoothing algorithm is used to optimize all tissue surfaces to reduce the influence of noise and maintain the authenticity of the anatomical structure. Laplace smoothing is an iterative smoothing algorithm based on mesh topology, which realizes surface smoothing by moving each vertex to the geometric center of its adjacent vertices while maintaining the overall shape unchanged.

[0059] S3: Assigning material attributes to the anatomical structures in the digitized dental arch model according to preset material parameters to obtain a biomechanical dental arch model.

[0060] Specifically, step S3 includes: The alveolar bone and the tooth are linearly elastic and isotropic material properties, and a first mechanical property model of hard tissue is obtained; the gingival and periodontal membrane are homogeneous material properties, and a second mechanical property model of soft tissue is obtained; the brackets and arch wires of different specifications are material properties, and a third mechanical property model of the appliance is obtained.

[0061] Specifically, the material property assignment of the present application is divided into three main parts: firstly, the alveolar bone and the tooth are linearly elastic and isotropic material properties, and a first mechanical property model of hard tissue is obtained, linear elasticity refers to the proportional relationship between strain and stress within a certain stress range, and isotropy means that the mechanical properties of the material in each direction are the same; secondly, the gingival and periodontal membrane are homogeneous material properties, and a second mechanical property model of soft tissue is obtained, homogeneous material refers to the uniform distribution of physical properties on a macroscopic scale, and although the microstructure of soft tissue is complex, it can be simplified as homogeneous material in mechanical simulation; finally, the brackets and arch wires of different specifications are material properties, and a third mechanical property model of the appliance is obtained.

[0062] Among them, the elastic modulus of the periodontal membrane is assigned as 0.68 MPa, and the Poisson's ratio is assigned as 0.45; the elastic modulus of the bone cortex is assigned as 13700 MPa, and the Poisson's ratio is assigned as 0.30; the elastic modulus of the cancellous bone is assigned as 1370 MPa, and the Poisson's ratio is assigned as 0.30; the elastic modulus of the tooth is assigned as 20300 MPa, and the Poisson's ratio is assigned as 0.30.

[0063] Further, the periodontal membrane is connective tissue connecting the tooth root and the alveolar bone, and the elastic modulus is assigned as 0.68 MPa, and the Poisson's ratio is assigned as 0.45, and the Poisson's ratio close to 0.5 indicates that it is close to incompressibility, reflecting the characteristics that the volume of the periodontal membrane hardly changes when stressed; the bone cortex is the dense bone on the outer layer of the alveolar bone, and the elastic modulus is assigned as 13700 MPa, and the Poisson's ratio is assigned as 0.30; the cancellous bone is the porous bone structure inside the alveolar bone, and the elastic modulus is assigned as 1370 MPa, and the Poisson's ratio is assigned as 0.30; the elastic modulus of the tooth body is assigned as 20300 MPa, and the Poisson's ratio is assigned as 0.30, and after the parameter assignment is completed, the data processing system enters these material parameters into the material library of the finite element analysis software to form a material parameter matrix, and the material parameters of each tissue are shown in Table 1.

[0064] Table 1 Material parameters of each tissue in material property assignment

[0065] ​​​​S4: The biomechanical dental model is iteratively analyzed over time using finite element analysis to obtain four-dimensional dynamic simulation data simulating the tooth movement process, and a visual orthodontic teaching demonstration is provided based on the four-dimensional dynamic simulation data.

[0066] The finite element analysis described above is a numerical calculation method that discretizes a complex physical system into a finite number of elements for analysis. Specifically, in the digital Typodont system of this invention, time-recursive iteration refers to the step-by-step calculation of the changes in various physical parameters during tooth movement in the time dimension. The purpose is to combine the three-dimensional spatial model with the time dimension to form a four-dimensional dynamic simulation, making the orthodontic treatment process visible. The final four-dimensional dynamic simulation data contains a complete set of information on the changes in spatial coordinates over time, recording the evolution of parameters such as tooth position and periodontal tissue stress distribution over time.

[0067] Step S4 further includes: S41: Set the fixed constraints for the maxilla and mandible to obtain the model reference.

[0068] Furthermore, the fixed constraint condition refers to setting the degrees of freedom of a specific region to zero in the finite element analysis, so that these regions remain stationary during the calculation. For the maxilla and mandible, this invention selects the temporomandibular joint region and the skull base connection site as fixed points. Specifically, firstly, for each constrained node, its displacement vector is set to 0, thereby establishing a spatial reference coordinate system for the entire model. Subsequently, the constraint conditions are transformed into linear equations and added to the global stiffness matrix. The obtained model reference refers to the spatial reference system established through the fixed constraint conditions, providing a fixed reference for subsequent calculations of relative tooth displacements.

[0069] S42: By setting the fixed contact between the teeth and the bracket and the sliding contact with gap between the bracket and the archwire, the force transmission mechanism of the model is obtained.

[0070] Contact conditions define the interaction between different components in finite element analysis. Fixed contact means that the two surfaces are completely bonded together, which is achieved in numerical calculations through shared nodes or multi-point constraint equations. In this invention, when setting fixed contact between teeth and brackets, the corresponding nodes of the two surfaces are rigidly connected by a program setting, so that they move as a whole. Frictional contact with gap is more complex, allowing relative movement between the bracket and archwire, but preventing them from penetrating each other.

[0071] In the calculation process, a contact detection algorithm is used to continuously search for potential contact point pairs, a penalty function method is used to impose contact constraints, the penalty function method simulates contact stiffness by adding virtual springs, aiming to improve numerical stability, the model force transmission mechanism refers to the mechanical transmission path constructed through these contact conditions, the orthodontic force is transmitted from the archwire to the bracket, and then from the bracket to the tooth, and finally acts on the periodontal tissue.

[0072] S43: Obtain the load distribution data borne by the plurality of parts of the dentition by simulating the process of restoring the archwire from the initial curved state to the straight state.

[0073] Further, the simulation of the archwire from the initial curved state to the straight state in step S43 is the core calculation of realizing the generation of orthodontic force. At the data processing level, first, the initial shape (curved state inconsistent with tooth arrangement) and the target shape (ideal straight state) of the archwire are defined, and then the deformation process between the initial shape and the target shape is discretized into a plurality of calculation sub-steps, and the elastic recovery force of the archwire is solved in each sub-step.

[0074] Specifically, in the calculation process of the load distribution data borne by the plurality of parts of the dentition, the displacement and stress state of each node of the archwire are tracked by setting a program, and the force and torque acting on the bracket are calculated by a contact algorithm. The final load distribution data is a complete mechanical state description, including the three-dimensional force vector and torque vector borne by each tooth position, and the obtained data records the distribution of orthodontic force in the entire dentition.

[0075] S44: Establish a dynamic simulation model based on the model benchmark reference, the model force transmission mechanism and the load distribution data.

[0076] The dynamic simulation model is a bridge connecting static mechanics analysis and time evolution, and the process of establishing the model is to convert the stress state calculated in the foregoing into a dynamic process changing with time. It should be noted that for the model of the present application, a biological feedback mechanism is realized in the model, that is, how the periodontal tissue responds to mechanical stimulation.

[0077] Wherein, step S44 further comprises: S441: Apply orthodontic force through elastic deformation of the archwire and calculate the initial displacement of the tooth under stress to obtain tooth movement data.

[0078] Further, in step S441, the corresponding force and moment are first applied to the tooth model according to the load distribution data calculated in step S43, and then the global stiffness matrix and node force vector are constructed, the displacement vector is obtained by solving the linear equation set, and the nonlinear characteristics of the periodontal membrane are considered in the calculation process, and the mechanical behavior is described by using piecewise linear approximation or hyperelastic model, and finally the tooth movement data obtained includes the translation displacement vector and rotation angle vector of each tooth position, which describes the instantaneous response of the tooth under the action of the initial orthodontic force.

[0079] S442: Update the alveolar bone geometry according to the tooth movement data to obtain the simulation results of bone resorption and remodeling.

[0080] Bone remodeling is a key biological process in orthodontic treatment, which determines the long-term behavior of tooth movement. Specifically, in step S442, the stress distribution of the periodontal membrane after tooth movement is first calculated, and the strain energy density method or the principal stress method is used to quantify the mechanical stimulation, and then according to the mechanical adaptability theory of Frost, the stress value of the periodontal membrane is substituted into the bone remodeling rate equation: that is, when the compressive stress exceeds the threshold value, bone resorption is triggered, and when the tensile stress exceeds the threshold value, bone formation is promoted. Subsequently, the geometry is updated by modifying the grid node coordinates, the bone surface nodes are moved inward in the compression area (simulate bone resorption), and the nodes are moved outward in the tension area (simulate bone formation), and the movement amount is proportional to the stress size and time step, and finally the bone resorption and remodeling simulation results are the updated alveolar bone grid model, which reflects the morphological changes of the bone tissue within a certain period of time.

[0081] S443: Synchronously adjust the geometry of the periodontal membrane by maintaining the constraint condition of the constant periodontal membrane gap to obtain an updated simulation model.

[0082] In step S443, the positions of the tooth root surface and the bone surface after updating are first determined, and then the geometry model of the periodontal membrane is reconstructed. The specific algorithm is that for each node of the tooth root surface, the normal vector is calculated, and the corresponding point on the outer surface of the periodontal membrane is determined by extending a predetermined distance along the direction. For complex areas (such as tooth root bifurcation), local coordinate transformation and interpolation algorithm are used to ensure uniform thickness of the periodontal membrane. The updated periodontal membrane model needs to be re-divided into grids and ensure that the element quality meets the numerical calculation requirements. The final updated simulation model includes the positions of the moved teeth, the morphologies of the remodeled alveolar bone, and the reconstructed periodontal membrane structure, which provides the initial conditions for the next round of iteration calculation.

[0083] S444: Update the updated simulation model in a loop to obtain a dynamic simulation model.

[0084] In step S444, the entire iteration process is managed by setting loop control parameters (such as the total number of iterations, convergence conditions, etc.), each iteration takes the output result of the previous step as the input condition of the next step, forming a closed-loop feedback system, and in each loop, a complete mechanical analysis-biological response-geometry update process is performed. The final dynamic model obtained after updating can save the complete model state at each key time point, including geometry information, mechanical parameters and displacement data, and can reflect the entire time evolution process of tooth movement.

[0085] S45: simulate the to-be-simulated tooth through the dynamic simulation model, and output four-dimensional dynamic simulation data of a simulated tooth movement process.

[0086] The output four-dimensional dynamic simulation data is a multi-dimensional data set containing complete information of spatial three-dimensional coordinates and time dimension, and the specific data structure includes: a time sequence geometry file (recording grid coordinates at each time step), a mechanical parameter file (recording stress-strain distribution), a displacement file (recording tooth movement trajectory), and a biological response file (recording bone remodeling amount). The four-dimensional dynamic simulation data not only shows the final result, but also reveals the mechanical state change in the entire process.

[0087] As shown in Figure 2 The application further provides a dynamic simulation system of a tooth movement process based on a Typodont model, comprising: A scanning module 100: configured to acquire data of artificial teeth and fixed appliances through three-dimensional scanning, and obtain three-dimensional data of a dental arch structure; An analysis module 200: configured to perform overlap analysis on a crown-root model according to the three-dimensional data, and obtain a digitized dental arch model containing periodontal tissue; An assignment module 300: configured to assign material properties to anatomical structures in the digitized dental arch model according to preset material parameters, and obtain a biomechanical dental arch model; A simulation module 400: configured to perform time recursion iteration on the biomechanical dental arch model through finite element analysis, obtain four-dimensional dynamic simulation data of a simulated tooth movement process, and provide visual orthodontic process teaching demonstration based on the four-dimensional dynamic simulation data.

[0088] The device embodiments described above are only schematic, wherein the units shown as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the embodiment scheme. Those skilled in the art can understand and implement without creative labor.

[0089] Those skilled in the art can clearly understand from the above description of the embodiments that the embodiments can be realized by means of software on the necessary general hardware platform, and of course, can also be realized by hardware. Based on such understanding, the above technical solutions, essentially or in terms of contribution to the prior art, can be embodied in the form of a software product. The computer software product can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, and the like, and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0090] The application realizes dynamic visual simulation and intelligent scoring of tooth movement by developing a high-precision three-dimensional dental model based on oral scanning data and forming a digital Typodont system, covering virtual bracket positioning, arch wire design, dynamic visual simulation of tooth movement, and simulation of complex intraoral conditions (such as periodontal conditions and occlusal force), to improve teaching interactivity and operation standardization, assist teaching and orthodontic beginner skill training, and break through the limitations of traditional Typodont feedback lag and difficulty in quantification.

[0091] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of dynamic simulation of tooth movement process based on Typodont model, characterized in that, The method comprises the following steps: S1: collecting data of artificial teeth and fixed appliances by three-dimensional scanning to obtain three-dimensional data of dental arch structure; S2: performing superimposition analysis on the crown and root model according to the three-dimensional data to obtain a digital dental arch model containing periodontal tissue; S3: assigning material properties to the anatomical structures in the digital dental arch model according to preset material parameters to obtain a biomechanical dental arch model; S4: performing time recursion iteration on the biomechanical dental arch model by finite element analysis to obtain four-dimensional dynamic simulation data simulating the tooth movement process, and providing visual orthodontic process teaching demonstration based on the four-dimensional dynamic simulation data.

2. The dynamic simulation method of tooth movement process based on Typodont model according to claim 1, wherein, The three-dimensional data in step S1 is collected by a first collection method or a second collection method.

3. The dynamic simulation method of tooth movement process based on Typodont model according to claim 2, characterized in that, The first collection method further comprises: S111: scanning artificial teeth by a three-dimensional scanner to obtain a tooth STL model; S112: placing artificial teeth in a standard occlusal wax ridge for full dentition scanning to obtain three-dimensional data of complete dentition; S113: collecting original digital files of different types of brackets and arch wires to obtain three-dimensional structure data of fixed appliances.

4. The dynamic simulation method of tooth movement process based on Typodont model according to claim 2, wherein, The second collection method further comprises: S121: scanning the subject by cone beam CT to obtain original tomographic data containing soft and hard tissue information; S122: scanning the dentition of the subject by an intraoral scanner to obtain surface information of the digital dental arch model; S123: scanning different specifications of appliances by a three-dimensional scanner to obtain three-dimensional data including straight wire bracket, edgewise bracket and different sizes of arch wire.

5. The dynamic simulation method of tooth movement process based on Typodont model according to claim 1, wherein, Step S2 further comprises: S21: aligning tooth models at different stages in the crown part by Geomagic software to obtain the three-dimensional spatial positional relationship of the crown part; S22: establishing the spatial position of the tooth root structure according to the three-dimensional spatial positional relationship to obtain a tooth model; S23: adding periodontal tissue structure data to the tooth model to obtain a digital dental arch model including periodontal membrane, gingiva and maxilla and mandible.

6. The dynamic simulation method of tooth movement process based on Typodont model according to claim 1, wherein, Step S3 specifically comprises: linear elastic and isotropic material property assignment is performed on the alveolar bone and teeth to obtain a first mechanical property model of hard tissue; homogeneous material property assignment is performed on the gingiva and periodontal membrane to obtain a second mechanical property model of soft tissue; material property assignment is performed on different specifications of brackets and arch wires to obtain a third mechanical property model of appliances.

7. The dynamic simulation method of tooth movement process based on Typodont model according to claim 6, wherein, The elastic modulus of the periodontal ligament is assigned a value of MPa, Poisson's ratio assigned a value of 0.45; elastic modulus of cortical bone assigned a value of MPa, Poisson's ratio assigned a value of 0.30; elastic modulus of cancellous bone assigned a value of MPa, Poisson's ratio assigned a value of 0.30; the elastic modulus of the tooth assigned a value of MPa, with a Poisson's ratio of 0.

30.

8. The dynamic simulation method of tooth movement process based on Typodont model according to claim 1, wherein, Step S4 further comprises: S41: setting fixed constraint conditions for the maxilla and mandible to obtain a model reference; S42: setting fixed contact between the teeth and brackets and gap sliding contact between the brackets and arch wires to obtain a model force transmission mechanism; S43: simulating the process of restoring the arch wire from the initial curved state to the straight state to obtain load distribution data of multiple parts of the dentition; S44: establishing a dynamic simulation model based on the model reference, the model force transmission mechanism and the load distribution data; S45: simulating the teeth to be simulated by the dynamic simulation model to output four-dimensional dynamic simulation data of the simulated tooth movement process.

9. The dynamic simulation method of tooth movement process based on Typodont model according to claim 8, wherein, Step S44 further comprises: S441: apply orthodontic force by elastic deformation of the archwire and calculate the initial displacement of the teeth under stress to obtain tooth movement data; S442: update the alveolar bone geometry according to the tooth movement data to obtain simulation results of bone resorption and reconstruction; S443: adjust the periodontal membrane geometry synchronously by maintaining the constraint condition of constant periodontal membrane space to obtain an updated simulation model; S444: cyclically update the updated simulation model to obtain a dynamic simulation model.

10. A dynamic simulation system of tooth movement process based on Typodont model, characterized in that, It comprises: a scanning module for data acquisition of artificial teeth and fixed appliances through three-dimensional scanning to obtain three-dimensional data of the dental arch structure; an analysis module for superimposition analysis of the crown-root model according to the three-dimensional data to obtain a digitized dental arch model containing periodontal tissue; an assignment module for material attribute assignment of the anatomical structure in the digitized dental arch model according to preset material parameters to obtain a biomechanical dental arch model; a simulation module for time-propagating iteration of the biomechanical dental arch model through finite element analysis to obtain four-dimensional dynamic simulation data simulating the tooth movement process, and to provide visual orthodontic process teaching demonstration based on the four-dimensional dynamic simulation data.

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