Orthodontic force analysis method and digital model optimization method for an orthodontic appliance

Abstract

The application provides an orthodontic force analysis method and an orthodontic appliance digital model optimization method. The orthodontic force analysis method comprises the following steps: obtaining a dynamic dental arch digital model of a dental arch to be corrected, the dynamic dental arch digital model being generated based on an actual occlusal relationship of upper and lower jaws; generating an orthodontic appliance digital model based on the dynamic dental arch digital model; simulating a wearing process of the orthodontic appliance by using the dynamic dental arch digital model and the orthodontic appliance digital model, and obtaining a distribution of the orthodontic force based on the simulation. The orthodontic force analysis method and the orthodontic appliance digital model optimization method can more accurately obtain the distribution of the orthodontic force exerted by the orthodontic appliance on the dental arch to be corrected and optimize the orthodontic appliance digital model.

Description

Technical Field

[0001] This application belongs to the field of orthodontic technology, specifically relating to orthodontic force analysis methods and digital model optimization methods for orthodontic appliances. Background Technology

[0002] With the advancement of technology and the development of the times, people are paying increasing attention to oral aesthetics and health, and orthodontic treatment has become widely popular. Orthodontics is a general term for treatment methods that correct deformities in various parts of the oral cavity, such as teeth, bones, and muscles. Examples include orthodontic treatment for misaligned teeth, arch expansion for crowded teeth, and bite guidance training for malocclusion. Because many patients often have multiple types of oral deformities requiring combined correction, orthodontic appliances capable of performing multiple types of orthodontic treatment simultaneously have emerged in recent years. These include bite guidance appliances for children in the mixed dentition stage who simultaneously have problems such as narrow dental arches, misaligned erupting teeth, and malocclusion caused by poor oral habits, as well as products such as invisible braces with attachments to guide the bite.

[0003] The aforementioned orthodontic appliances used for orthodontic treatment are generally designed and manufactured using digital methods. To ensure orthodontic effectiveness, an evaluation of the orthodontic effect is usually required during the design phase. In recent years, with the improvement of the accuracy of digital modeling and the development of digital simulation technology, various methods have been proposed for designing orthodontic appliances using digital technology and verifying their orthodontic effects through simulation. For example, patent 201810163484.X proposes a method for designing and manufacturing a shell-shaped orthodontic appliance for aligning teeth. It uses a digital model of the teeth to design a digital model of the shell-shaped orthodontic appliance and obtains the force situation of the teeth after wearing the shell-shaped orthodontic appliance through finite element simulation. Another example is patent 201380007617.X, which determines one or more forces applied to the teeth by virtually placing dental instruments on a set of virtual teeth.

[0004] However, the above methods are not suitable for simulating the orthodontic effects of appliances with combined orthodontic functions. The main reasons are as follows: First, these methods are generally based on force-torque theory, using linear finite element methods to calculate the corrective forces and resulting displacements on teeth from the shell-shaped appliance (invisible aligner). However, simulating the corrective effects of appliances such as occlusal guiding appliances requires incorporating the jawbone into the biomechanical simulation analysis. This allows for a more accurate determination of the forces between the orthodontic appliance and human tissues such as teeth, gums, alveolar bone, and maxillae, as well as the impact on soft tissues like muscles. Such biomechanical models involve complex nonlinear interactions; therefore, simply using linear finite element methods for simulation cannot reflect the complex biomechanical processes involved in orthodontics. The methods described above generally simulate the force exerted on teeth by shell-shaped clear aligners made of resin materials. These aligners are relatively rigid and typically act solely on the maxillary or mandibular dentition. Therefore, it is generally only necessary to consider the force exerted after the aligner is stably fitted into the dentition. However, for bite-inducing aligners made of soft silicone materials, different occlusal relationships and occlusal forces will cause different changes in the aligner during the dynamic wearing process of biting the upper and lower teeth into the aligner, resulting in different distributions of orthodontic force on the oral tissues. Therefore, performing only static simulations after the aligner is fitted will lead to significant errors in the simulation results, thus affecting the evaluation of orthodontic effects. Summary of the Invention

[0005] To address the problems and deficiencies in the prior art, the purpose of this application is to provide a method for accurately acquiring and analyzing various types of orthodontic forces exerted by the orthodontic appliance on different tissues in the oral cavity, and a method for optimizing the digital model of the orthodontic appliance based on the acquired orthodontic forces.

[0006] One aspect of this application provides an orthodontic force analysis method for analyzing the distribution of orthodontic forces applied by an orthodontic appliance to the teeth to be treated, comprising the following steps:

[0007] S1: Obtain a dynamic digital model of the dentition to be treated, which is generated based on the actual occlusal relationship between the upper and lower jaws;

[0008] S2: Generate a digital model of the orthodontic appliance based on the dynamic digital model of the jaw;

[0009] S3: The wearing process of the orthodontic appliance is simulated using the dynamic dental digital model and the orthodontic appliance digital model, and the distribution of the orthodontic force is obtained based on the simulation.

[0010] Furthermore, the orthodontic force includes at least one of the following corrective forces: corrective force on at least one tooth, corrective force on the maxilla and / or mandible, and traction force on the condyle.

[0011] Furthermore, the actual occlusal relationship includes: the relative positional relationship of the upper and lower jaws in a non-occlusal state, the relative positional relationship of the upper and lower jaws in an occlusal state, and the motion parameters of the condyle during the occlusal process.

[0012] Furthermore, the motion parameters of the condyle during occlusion include the inclination angle and / or the motion trajectory curve of the condyle during occlusion.

[0013] Further, step S3 includes the following steps:

[0014] S31: Set the finite element constitutive parameters for the dynamic digital model of the jaw and the digital model of the orthodontic appliance;

[0015] S32: Set finite element calculation parameters;

[0016] S33: Set the initial values ​​for the wearing parameters;

[0017] S34: Based on the initial values ​​of the finite element calculation parameters and the wearing parameters, the wearing process is simulated using the finite element calculation method to determine the wearing parameters and the distribution of the orthodontic force at any time during the wearing process.

[0018] Furthermore, the finite element constitutive parameters include at least one of the following parameters: material parameters, element parameters, and model type.

[0019] Preferably, the wearing parameters include: the shape of the digital model of the orthodontic appliance, the shape of the dynamic dental digital model, the relative positional relationship between the digital model of the orthodontic appliance and the dynamic dental digital model during the wearing process, the motion parameters of the condyle during the wearing process, and the biting force of the upper and lower jaws during the wearing process.

[0020] Preferably, the motion parameters of the condyle during the wearing process include the tilt angle and / or the motion trajectory curve of the condyle during the wearing process.

[0021] Preferably, the biting force of the upper and lower jaws during the wearing process is obtained by sensors set on the dynamic digital model of the jaw.

[0022] Preferably, the simulation ends when the biting force of the upper and lower jaws during the wearing process exceeds the average value of the maximum biting force limit of a human in a waking state.

[0023] Preferably, the finite element calculation method uses a nonlinear calculation method.

[0024] Preferably, the finite element calculation parameters include: the contact conditions and boundary conditions between the digital model of the orthodontic appliance and the dynamic digital model of the jaw.

[0025] Preferably, the boundary condition includes the loading speed.

[0026] Preferably, the loading speed is 0.001 m / s to 3 m / s; the finite element calculation parameters also include damping parameters.

[0027] Preferably, the distribution of orthodontic forces includes the magnitude and direction of orthodontic forces acting on at least one part of the dynamic digital dental model.

[0028] Preferably, the orthodontic force analysis method further includes the step of displaying the simulation process and the distribution of orthodontic force on a display device.

[0029] Preferably, the orthodontic appliance is used to align teeth, adjust the dental arch shape of the maxilla and / or mandible, and adjust the occlusal relationship between the maxilla and mandible.

[0030] Preferably, the actual occlusal relationship is obtained by measuring the teeth to be treated using an articulator.

[0031] Another aspect of this application provides a method for optimizing a digital model of an orthodontic appliance, comprising the following steps:

[0032] Step 1: Based on the above orthodontic force analysis method, determine the distribution of orthodontic force generated by the orthodontic appliance manufactured based on the current digital model of the appliance after it is worn on the upper and lower jaws;

[0033] Step 2: Optimize the current digital model of the orthodontic appliance based on the distribution of orthodontic forces to obtain the optimized digital model of the orthodontic appliance.

[0034] The orthodontic force analysis method and the orthodontic appliance digital model optimization method provided in the embodiments of this application have at least the following beneficial effects:

[0035] (1) The technical solution of this application uses a dynamic digital model of the jaw to simulate the wearing process of the orthodontic appliance. The dynamic digital model of the jaw is established according to the actual occlusal relationship, and the different occlusal processes of the upper and lower jaws, such as opening and closing movements, protrusion and retraction movements, and lateral occlusal movements, are abstracted into parameters such as condylar movement trajectories. This makes the relative movement of the upper and lower jaws realistically reproduced when simulating the wearing process of the orthodontic appliance, thereby improving the credibility of the finite element simulation results.

[0036] (2) The technical solution of this application changes the static and linear finite element calculation method used in the existing simulation method of orthodontic appliance treatment effect. It uses a dynamic and nonlinear finite element calculation method to calculate the distribution of orthodontic force at any time during the wearing process. Through this method, the changes of alignment force, arch expansion force, and traction force applied to different parts of the teeth and jaws during the wearing process of the appliance, as well as the changes in the shape of the appliance, can be dynamically obtained. Based on the above information, richer data support can be provided for judging the treatment effect of the appliance and further optimizing the design of the appliance.

[0037] (3) By setting forced loading conditions such as forced loading speed and correspondingly increasing parameters such as mass damping, the oscillation problem of the model structure caused by high-speed motion is avoided while improving the efficiency of finite element calculation, thus achieving a balance between calculation effect and calculation accuracy. Attached Figure Description

[0038] Figure 1 A three-dimensional diagram of an existing shell-shaped orthodontic appliance;

[0039] Figure 2A A three-dimensional view of an existing bite-inducing orthodontic appliance;

[0040] Figure 2B Rear view of an existing bite-inducing orthodontic appliance;

[0041] Figure 2C A top view of an existing bite-inducing orthodontic appliance;

[0042] Figure 2D for Figure 2C CC-direction sectional view of the bite guidance appliance in the middle;

[0043] Figure 2E for Figure 2C A DD-direction sectional view of the bite-guiding orthodontic appliance in the middle;

[0044] Figure 3 A schematic diagram of the upper and lower jaws connected by the temporomandibular joint;

[0045] Figure 4A This is a schematic diagram illustrating the movement patterns of the mandible relative to the maxilla.

[0046] Figure 4B This is a diagram illustrating the opening and closing of the lower jaw relative to the upper jaw.

[0047] Figure 4C A schematic diagram showing the protrusion and retraction of the mandible relative to the maxilla;

[0048] Figure 4D This is a schematic diagram of the mandible sliding laterally relative to the maxilla;

[0049] Figure 5 The curve showing the change of biting force over time during the biting process of a specific upper and lower jaw;

[0050] Figure 6 This is a flowchart of the orthodontic force analysis method according to an embodiment of this application;

[0051] Figures 7A to 7C This is a schematic diagram of a dynamic digital model of the jawbone during an opening process according to a specific embodiment of this application;

[0052] Figure 8 This is a flowchart illustrating the creation of a dynamic digital model of the jaw according to a specific embodiment of this application;

[0053] Figure 9 This is a schematic diagram illustrating a specific implementation method for obtaining the actual occlusal relationship using an articulator;

[0054] Figure 10 This is a schematic diagram illustrating a specific implementation method for obtaining the actual occlusal relationship using a lateral cephalometric radiograph.

[0055] Figure 11 This is a flowchart of step S3 according to an embodiment of this application;

[0056] Figure 12 This is a schematic diagram illustrating the setting of boundary conditions according to a specific embodiment of this application;

[0057] Figures 13A to 13D The finite element simulation results of the appliance and changes in dentition and jaw morphology at different stages of a specific wearing process are shown respectively;

[0058] Figure 14A , Figure 14B The different wearing effects produced by setting different initial values ​​for the motion parameters of the condyle during the wearing process, obtained through finite element simulation, are shown respectively.

[0059] Figures 15A to 15C The results of finite element simulation show the distribution of orthodontic forces on the teeth and jawbone at different stages of a specific wearing process.

[0060] Figure 16 The results are finite element simulations of the traction forces experienced by the condyle at different stages of a specific wearing process.

[0061] Figure 17 A comparison of structural oscillations in digital models of the orthodontic appliance before and after adding mass damping, obtained through finite element simulation.

[0062] Figure 18 The stress-strain curves of different materials used in the orthodontic appliance are obtained through finite element simulation. Detailed Implementation

[0063] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings.

[0064] Furthermore, for ease of understanding, various components on the drawings have been enlarged or reduced, but this is not intended to limit the scope of protection of this application.

[0065] Singular forms of words also include plural meanings, and vice versa.

[0066] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, in the description of this application, in order to distinguish different units, the terms "first," "second," etc. are used in this specification, but these are not limited by the manufacturing order, nor should they be construed as indicating or implying relative importance. Their names may differ in the detailed description and claims of this application.

[0067] The vocabulary used in this specification is for illustrative purposes and is not intended to limit the scope of this application. It should also be noted that, unless otherwise expressly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection via an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of these terms in this application.

[0068] To better illustrate the technical solution of this application, we first explain the corrective mechanism of orthodontic appliances used in oral orthodontics.

[0069] Figure 1 This image shows a shell-shaped orthodontic appliance (or invisible aligner) for aligning teeth, primarily used to correct misalignment issues such as labial inclination, lingual inclination, and rotation of teeth. Figure 1As shown, the shell-shaped orthodontic appliance 100 has multiple shells 101 for accommodating teeth. The inner wall of each shell 101 forms a cavity 102 with the same shape as the crown portion of the corresponding tooth. The multiple shells are arranged according to the ideal position of their respective teeth to form a U-shaped alveolar groove. The shell-shaped orthodontic appliance 100 is generally made of resin material with a certain degree of hardness and elasticity. When it is worn on the dentition that needs correction, due to the difference between the position of some (or all) teeth and the ideal position, some / or all of the shells deform and generate a rebound force to return to their initial shape. This rebound force acts on the misaligned teeth, causing the teeth to gradually move towards the ideal position, thereby achieving the effect of correcting malocclusion. In actual orthodontic treatment, in order to avoid excessive deformation of the shell-shaped appliance, which would result in excessive orthodontic force applied to the teeth or excessively fast tooth movement, causing various discomforts, pains, or even risks such as bone fractures, it is generally necessary to divide the entire orthodontic cycle into multiple stages and manufacture shell-shaped appliances corresponding to each stage, so as to realize the movement of the dentition from the initial alignment state to the ideal alignment state step by step.

[0070] Clearly, calculating and simulating the forces acting on teeth after the aforementioned shell-shaped orthodontic appliance is fitted into the dentition allows for advance analysis and evaluation of its orthodontic effect, or further optimization of its shape and structure. Currently, various calculation and simulation methods are available. For example, theoretical calculations of the movement of the dentition under the action of the shell-shaped appliance can be obtained based on the biomechanical properties of oral tissues; alternatively, finite element simulation can be used to establish separate finite element models of the shell-shaped appliance and the dentition, assembling them together, and then using finite element calculations to obtain the forces and movements of the teeth.

[0071] However, for some patients, the oral problems they face and their causes can be diverse and complex. For example, children in the mixed dentition stage may simultaneously have problems such as malocclusion of primary teeth, malocclusion of permanent teeth, crowding, and malocclusion of the upper and lower jaws. The causes of these problems include, but are not limited to, misaligned tooth eruption, insufficient dental arch width due to delayed development of the jawbone, and incorrect muscle positioning and force application habits caused by poor oral habits. Obviously, shell-shaped orthodontic appliances, which are simply used to align teeth, cannot be applied to such complex orthodontic procedures.

[0072] In recent years, orthodontic treatment methods and products based on the concept of occlusion guidance have become known to those skilled in the art and have been applied in orthodontic procedures for children. Occlusion guidance utilizes the plasticity of early tooth and jawbone development, and through the application of gentle forces in multiple directions, it can achieve operations such as interdental space treatment and micro-movement, partial grinding of deciduous teeth, expansion of dental arch, and adjustment of the occlusal relationship between the upper and lower jaws. This can block the development of various oral deformities and restore all oral tissues to their normal developmental track, thereby achieving overall coordination and balance between the function and aesthetics of the skull, jaw, teeth, and face.

[0073] Figures 2A to 2C A perspective view, a rear view, and a top view of an existing orthodontic appliance with bite guidance function are shown. Figure 2D , Figure 2E These are sectional views along the CC and DD directions, respectively. For example... Figures 2A to 2E As shown, the orthodontic appliance 200 includes a generally U-shaped outer wall 210 and an inner wall 220, and an occlusal pad 230 connecting the inner wall 210 and the outer wall 220. Further, the outer wall 210 can be subdivided into an upper outer wall 211 and a lower outer wall 212, and the inner wall 220 can be subdivided into an upper inner wall 221 and a lower inner wall 222. The inner surface of the upper outer wall 211, the inner surface of the upper inner wall 221, and the upper surface of the occlusal pad 230 form an upper alveolar 240 for accommodating the maxillary dentition. The inner surface of the lower outer wall 212, the inner surface of the lower inner wall 222, and the lower surface of the occlusal pad 230 form a lower alveolar 250 for accommodating the mandibular dentition.

[0074] The occlusion guiding appliance 200 is designed to apply alignment forces to guide tooth alignment, apply arch-expanding forces to the maxilla and mandible to expand the dental arch, and apply traction to the temporomandibular joint and surrounding muscles to adjust the occlusal relationship of the maxilla and mandible. Specifically, such as Figures 2C to 2E As shown, the labial and lingual inner surfaces of the alveolar bone are designed to match the crown surfaces of the aligned teeth, thereby guiding the teeth to make minute movements to align; it extends along the mesiodistal direction according to the desired dental arch curve (e.g., Figure 2C (as shown by the dotted line in the image); at the same time, by adjusting parameters such as the thickness and tilt angle of the occlusal pad at different locations, the relative positional relationship between the upper and lower alveoli is set according to the desired maxillary occlusal relationship for orthodontic treatment.

[0075] Occlusal guiding appliances are generally made of soft medical-grade silicone and other materials. They are easily deformed under force and have less resilience compared to resin materials, thus allowing for gentler application of force to the gums, jawbone, and soft tissues in different parts of the oral cavity.

[0076] Similar to shell-type orthodontic appliances, after designing the digital model of the aforementioned occlusal guiding orthodontic appliance, the distribution of orthodontic force after wearing it can be analyzed using finite element simulation to evaluate its expected orthodontic effect or further optimize the design. However, existing finite element simulation methods used for shell-type orthodontic appliances are not suitable for simulating and calculating the orthodontic force distribution of the aforementioned occlusal guiding orthodontic appliances. This is because the complexity of simulating the orthodontic force distribution generated by occlusal guiding orthodontic appliances is far greater than that of shell-type orthodontic appliances.

[0077] (1) Most existing finite element simulation methods for the orthodontic effect of shell-shaped orthodontic appliances focus on calculating the orthodontic force on the teeth after wearing. The reason is that the finite element model of the teeth is generally set as a rigid body, while the finite element model of the shell-shaped orthodontic appliance is generally set as an elastic body with a large elastic modulus. After the appliance is assembled, it undergoes overall deformation. Moreover, the relative positional relationship between the dentition and the shell-shaped orthodontic appliance is independent of the wearing process. Therefore, the process of assembling the appliance into the dentition is generally simplified to an ideal situation. For example, during the assembly process, all degrees of freedom of the orthodontic appliance model at selected nodes and all degrees of freedom of the orthodontic appliance model in other selected nodes except for the wearing direction are restricted. Alternatively, several nodes are randomly selected at each tooth shape of the orthodontic appliance model and set as rigid connections.

[0078] After assembly is completed in the above ideal and simplified manner, linear calculation methods are generally used to perform finite element simulation on the static integrated finite element model after assembly.

[0079] (2) Unlike shell-shaped orthodontic appliances, the wearing process of bite-inducing orthodontic appliances and the orthodontic forces applied to different parts and tissues of the oral cavity are more complex. Different bite processes will lead to different orthodontic force distributions after wearing.

[0080] Figure 3 A schematic diagram of the maxilla and mandible connected by the temporomandibular joint is shown. Figures 4A to 4C It illustrates various movements of the mandible. For example... Figure 3 and Figures 4A to 4D As shown, the maxillary portion 310 (generally, the maxillary portion 310 includes the maxilla and the maxillary dentition contained therein, and also includes soft tissues such as the gingiva and periodontal ligament, not shown in the figure) and the mandibular portion 320 (generally, the mandibular portion 320 includes the mandible and the mandibular dentition contained therein, and also includes soft tissues such as the gingiva and periodontal ligament, not shown in the figure) are connected by the temporomandibular joint. The temporomandibular joint includes an articular disc, a joint capsule, and a condyle 330 located therein that can rotate and translate. When the mandibular portion 320 is subjected to force by different muscle groups such as the masseter, temporalis, medial pterygoid, and lateral pterygoid muscles, it performs various movements relative to the maxillary portion 310 (such as... Figures 4A to 4DWhen the mandibular portion 320 moves relative to the maxillary portion 310 (such as opening, closing, protruding, retracting, and lateral shifting), the condyle 330 is simultaneously pulled to rotate and translate accordingly, thus forming a specific motion trajectory or motion curve.

[0081] Figure 5 This illustrates a curve showing the change in occlusal force over time during the specific process of upper and lower jaw occlusion, such as... Figure 5 As shown, in daily life, normal chewing force is between 10-25 kg, and the conscious biting force is between 25-75 kg. Within this conscious biting force range, excessive force on the teeth causes pain in the periodontal ligament. The brain, through nerve control, immediately reduces the force of the biting muscles, thus preventing damage to the teeth, gums, and periodontal ligament. It is precisely because the periodontal ligament has this protective physiological regulatory function that it avoids the damage that might occur when biting. However, bruxism (teeth grinding) is an involuntary bite, and the body cannot effectively regulate muscle force. Therefore, the biting force during bruxism can reach over 100 kg, greater than the conscious biting force during the day.

[0082] Considering the connection between the upper and lower jaws and their different movement patterns and applied occlusal forces during various occlusal processes, as well as the relatively soft material properties of the occlusal guiding appliance, the wearing state (including the position and depth of the jawbone and dentition entering the alveolar bone, and the deformation of various parts of the appliance) achieved by different occlusal processes (including but not limited to different condylar movement trajectories and different occlusal forces applied by various muscle groups) when wearing the occlusal guiding appliance varies significantly. These differences will in turn lead to significant differences in the distribution of various orthodontic forces applied by the occlusal guiding appliance to the dentition, jawbone, condyle, and other parts, and further produce different orthodontic effects.

[0083] As can be seen from the above analysis, in order to accurately simulate the distribution of orthodontic forces generated by occlusal induction appliances and similar appliances acting on various tissues in the oral cavity, it is necessary to improve the existing finite element simulation methods in many aspects, such as model type, simulation process and parameters, so that the calculation results are more consistent with the actual wearing and treatment situation.

[0084] To achieve the above objectives, one aspect of the embodiments of this application provides an orthodontic force analysis method. Figure 6 A flowchart of an orthodontic force analysis method according to an embodiment of this application is shown, such as... Figure 6 As shown, the above orthodontic force analysis method includes the following steps:

[0085] S1: Obtain a dynamic digital model of the dentition to be treated, which is generated based on the actual occlusal relationship between the upper and lower jaws;

[0086] S2: Generate a digital model of the orthodontic appliance based on the dynamic digital model of the jaw;

[0087] S3: The wearing process of the orthodontic appliance is simulated using the dynamic dental digital model and the orthodontic appliance digital model, and the distribution of the orthodontic force is obtained based on the simulation.

[0088] The specific implementation methods of steps S1 to S3 are described below with reference to the accompanying drawings.

[0089] Step S1 is used to obtain a dynamic digital model of the dentition of a patient who will undergo orthodontic treatment.

[0090] Existing technologies offer various methods for creating digital models of the jaw, employing techniques such as optical scanning, X-ray / ultrasound imaging, CT scanning, or MRI to acquire three-dimensional digital models encompassing teeth, periodontal tissues, and the jawbone. The data format and integration level of these digital models can be adjusted according to specific application requirements. For example, when only the external structure of the jaw needs to be displayed, triangular facets can be used to form the contours of teeth, periodontal tissues, and the jawbone. When finite element simulation of orthodontic treatment is required, each of these parts needs to be solidified and assigned different parameters to form finite element models of teeth, gingiva, periodontal ligament, and jawbone. Furthermore, separate digital models of the maxilla and mandible can be created for tooth arrangement in the maxillary and mandibular dentitions, respectively, or for simulating the treatment effect of shell-type orthodontic appliances. Alternatively, a three-dimensional registration technique can be used to place the maxillary and mandibular digital models according to their actual positional relationships in three-dimensional space, thus forming an "integrated" digital model of the jaw.

[0091] However, the "integrated" digital dental models in the aforementioned prior art often present a fixed positional relationship between the maxilla and mandible. They only reflect the relative positional relationship between the maxilla and mandible at the moment the dental model is scanned and photographed, and cannot reproduce the various occlusal processes of the mandible relative to the maxilla. In contrast, in the embodiments of this application, the digital dental model established in step S1 is a dynamic digital dental model that can accurately reproduce the occlusal process of the maxilla and mandible.

[0092] Figures 7A to 7C The diagram illustrates a dynamic dental model reproducing the opening process according to some specific embodiments of this application, such as... Figures 7A to 7CAs shown, the dynamic digital dental model 400 includes a maxillary model 410 and a mandibular model 420. In some specific embodiments, the maxillary model 410 and the mandibular model 420 can be further subdivided according to different parts into multiple maxillary tooth models 411, maxillary gingival models 412, multiple mandibular tooth models 421, mandibular gingival models 422, and models of parts such as the maxillary bone, mandibular bone, maxillary periodontal ligament, and mandibular periodontal ligament located within the gingiva (not shown).

[0093] In some embodiments, the dynamic dental digital model 400 also includes an upper abutment model 413 and a lower abutment model 423 adapted to the tooling fixture to facilitate assembly, manufacturing, and other needs in subsequent orthodontic procedures.

[0094] In some embodiments, the digital models of the different parts can be assigned corresponding materials to form finite element models that can be used for simulation. Obviously, when performing finite element simulation of orthodontic forces on the jawbone, the upper abutment model and the lower abutment model do not need to be converted into finite element models, nor do they need to participate in the finite element simulation.

[0095] It should be emphasized that, in the embodiments of this application, the movement of the mandibular portion relative to the maxillary portion constituting the dynamic dental digital model is limited by the actual occlusal relationship between the upper and lower jaws. That is, the dynamic dental digital model is generated based on the actual occlusal relationship between the upper and lower jaws, and its movement process follows the limitations of the actual occlusal relationship between the upper and lower jaws without wearing any dental instruments.

[0096] Specifically, in some embodiments of this application, the actual occlusal relationship of the upper and lower jaws includes the relative positional relationship of the upper and lower jaws in a non-occlusal state, the relative positional relationship of the upper and lower jaws in an occlusal state, and the motion parameters of the condyle during the occlusal process.

[0097] like Figure 3 As shown, the temporomandibular joint, as the link connecting the upper and lower jaws, can perform complex and flexible movements under the control of multiple muscle groups in the oral cavity to achieve various types of occlusion. During the above-mentioned various types of occlusion, the actual occlusal relationship of the upper and lower jaws can be characterized by the relative positional relationship of the upper and lower jaws in the occlusal state (i.e., the closed state), the relative positional relationship of the upper and lower jaws in the non-occlusal state (i.e., different open states), and the movement parameters of the condyle in various types of occlusion.

[0098] The condyles, also known as condylar processes or articular processes, are the two projections at the end of the mandibular ramus of the mandible, located in the glenoid fossa of the temporomandibular joint. During various types of biting relative to the maxilla, the condyles, when pulled, can perform large-angle, wide-range rotational and translational movements. Recording the motion parameters of these movements allows for accurate acquisition of the actual occlusal relationship between the maxilla and mandible. In some specific embodiments of this application, the movement of the condyles can be simplified to a linear rotational and translational movement, i.e., the motion parameter of the condyles during biting is the inclination angle of the condyle's motion trajectory during biting (the inclination angle can be the angle between the straight line of the condyle's motion trajectory and the horizontal plane or a specific measurement marker line of the maxilla); in other specific embodiments of this application, the motion parameter of the condyles during biting can also be the curve of the condyle's motion trajectory during biting.

[0099] Still with Figures 7A to 7C Taking the dynamic digital model of the jaw 400 as an example to reproduce the opening process, in the figure, point AX (labeled as 430) is the equivalent position point of the condyle. As the relative positional relationship between the mandibular model 420 and the maxillary model 410 gradually changes from an occlusal state to a non-occlusal state, it drives point AX 430 to translate along the dotted line in the figure (which forms a fixed angle with the horizontal line OP), and at the same time rotates around point AX 430, thereby completing the opening process.

[0100] The above examples illustrate the actual occlusal relationship followed by the dynamic digital model of the jaw when reproducing the opening process. Obviously, when reproducing other types of occlusal processes, the dynamic digital model of the jaw follows the corresponding actual occlusal relationship.

[0101] Figure 8 A flowchart illustrating the creation of a dynamic digital model of the jaw according to a specific embodiment of this application is shown, such as... Figure 8 As shown, a three-dimensional scan of a plaster model of the jaw can be performed first to establish digital models of the maxilla and mandible, as well as an overall digital model of the jaw. Then, multiple pairs of positioning markers are marked on each of the digital models, and three-dimensional registration technology is used to register the maxilla and mandible, obtaining the relative positional relationship of the maxilla and mandible in the occlusal state (steps S11 to S14). Based on this, the relative positional relationship of the maxilla and mandible in the non-occlusal state and the corresponding condylar motion parameters are further obtained to determine the motion trajectory of the mandible in various types of occlusion processes. This trajectory is then bound to the mandibular digital model, thus obtaining a dynamic digital model of the jaw based on the actual occlusal relationship (steps S15 to S17).

[0102] In some optional embodiments of this application, an articulator can be used to measure the relative positional relationship between the upper and lower jaws in occlusal and various non-occlusal states. Figure 9A schematic diagram illustrating the use of a jawbone frame to measure the relative positional relationship between the upper and lower jaws is shown, as follows: Figure 9 As shown, the jaw frame 500 can measure and record the position and posture data of the upper and lower jaws under different occlusal states, as well as the corresponding temporomandibular joint motion data (the condyle can be located through measurement point 530 in the figure). Furthermore, the measurement data from multiple locations can be fitted to obtain the motion parameters of the condyle during the above-mentioned occlusal process.

[0103] In some other optional embodiments of this application, the above data can also be obtained based on measurement methods such as X-ray films. Figure 10 A specific lateral cephalometric radiograph is shown. Multiple measurement landmarks can be manually or automatically marked on the radiograph to obtain various measurement landmark lines. By performing the above processing on lateral cephalometric radiographs under various occlusal states, information on the actual occlusal relationship can also be obtained based on the changes in the measurement landmarks and occlusal measurement landmark lines.

[0104] After obtaining the above-mentioned actual occlusal relationship, it is necessary to use the above-mentioned actual occlusal relationship to bind the upper and lower jaws. In some specific embodiments of this application, the movement trajectory of the mandible relative to the maxilla is obtained based on the above-mentioned actual occlusal relationship, and then the above-mentioned movement trajectory is bound to the mandibular digital model, thereby obtaining a dynamic dental digital model generated based on the actual occlusal relationship.

[0105] In some specific embodiments of this application, the actual occlusal relationship described above may be non-visual, such as the positional information of the mandible relative to the maxilla at multiple moments during the occlusal process represented by a series of three-dimensional coordinates and posture data, or the movement trajectory information of the mandible during the occlusal process represented by an analytical three-dimensional spatial curve.

[0106] In other specific embodiments of this application, to more clearly demonstrate various occlusal processes, the aforementioned actual occlusal relationships can also be visualized, such as... Figures 7A to 7C The dynamic digital model of the jaw shows the condyle as an equivalent AX point, and the actual occlusal relationship is converted into motion parameters such as the condyle's movement trajectory tilt angle / or movement trajectory curve during the actual occlusal process for visualization.

[0107] The process of establishing a dynamic dental digital model has been described in detail above with reference to the accompanying drawings and specific embodiments. After obtaining the dynamic dental digital model, in step S2, a digital model of the orthodontic appliance is designed and generated based on the dynamic dental digital model. Unlike shell-shaped orthodontic appliances used only for aligning teeth, this appliance can be used to align teeth, adjust the dental arch morphology of the maxilla and / or mandible, and adjust the occlusal relationship between the maxilla and mandible.

[0108] For example, in some preferred embodiments, the orthodontic appliance may be the bite-inducing appliance described above, which, after being worn by biting the upper and lower jaws, can apply different types of orthodontic forces to different parts and tissues in the oral cavity. The orthodontic forces include at least one of the following forces: orthodontic force on at least one tooth, orthodontic force on the maxilla and / or mandible, and traction force on the condyle.

[0109] For example, in some other preferred embodiments, the orthodontic appliance can be an orthodontic system consisting of two shell-shaped appliances worn on the maxilla and mandible, an arched reinforcing structure on the palatal side of the shell-shaped appliances, and a pair of attachments on the occlusal, labial, buccal, or lingual sides of the two shell-shaped appliances. Similar to occlusal guiding appliances, this orthodontic system can also apply different types of orthodontic forces to different parts and tissues in the oral cavity, including the orthodontic force applied to the teeth by its shell-shaped cavity, the arch-expanding force applied to the jawbone by its arched reinforcing structure, and the traction force applied to the condyle by the pair of attachments that traction the maxilla and mandible.

[0110] The digital model of the aforementioned orthodontic appliance can be digitally modeled manually or automatically / semi-automatically by experienced modelers based on the doctor's diagnosis and prescription of the patient's dynamic dental digital model. A typical orthodontic prescription generally includes the expected goals of the orthodontic procedure (e.g., the morphology or parameters of the aligned dentition, the expected width of the dental arch after expansion, the adjusted occlusal relationship of the upper and lower jaws, etc.), the range of orthodontic forces to be applied to various parts of the dental jaw to achieve the above goals, the duration of the orthodontic procedure, the duration of daily appliance wear during orthodontic treatment, and the range of additional bite training forces required. After obtaining the above prescription, experienced modelers can adjust the dynamic dental digital model to form the target dental model expected to be achieved during the orthodontic procedure. Furthermore, based on the target dental model and combined with the required orthodontic force information and treatment period information, an orthodontic appliance digital model or a set of progressively changing treatment period digital models can be designed. The above-mentioned method for designing digital models of orthodontic appliances based on the patient's dental and jaw models and the doctor's prescription is known to those skilled in the art and will not be described in detail here.

[0111] After obtaining the dynamic dental digital model and the orthodontic appliance digital model through steps S1 and S2 respectively, step S3 is used to simulate the process of wearing the orthodontic appliance to obtain the distribution of orthodontic forces acting on different parts and tissues of the dental jaw during the wearing process. In some preferred embodiments of this application, the distribution of orthodontic forces obtained based on the simulation includes the magnitude and direction of the orthodontic force acting on at least one part of the dynamic dental digital model, as well as the changes in the orthodontic force during the wearing process.

[0112] As analyzed above, existing methods for simulating the orthodontic effects of shell-shaped orthodontic appliances often only employ idealized and simplified treatments for the wearing / fitting process, without simulating the different wearing results caused by variations in wearing angle, speed, and applied occlusal force. For shell-shaped orthodontic appliances used solely for maxillary or mandibular tooth alignment, this simplification is reasonable and does not affect the subsequent simulation accuracy. However, for softer orthodontic appliances such as bite-inducing appliances that act on both the maxilla and mandible simultaneously, the lack of a more detailed analysis of the wearing process will significantly increase the simulation error of the orthodontic effect after the appliance is worn.

[0113] Figure 11 For the implementation process of step S3 according to some specific embodiments of this application, such as Figure 11 As shown, step S3 further includes the following steps:

[0114] S31: Set the finite element constitutive parameters for the dynamic digital model of the jaw and the digital model of the orthodontic appliance;

[0115] S32: Set finite element calculation parameters;

[0116] S33: Set the initial values ​​for the wearing parameters;

[0117] S34: Based on the initial values ​​of the finite element calculation parameters and the wearing parameters, the wearing process is simulated using the finite element calculation method to determine the wearing parameters and the distribution of the orthodontic force at any time during the wearing process.

[0118] The finite element constitutive parameters set in step S31 may include material parameters, element parameters, and model type of the dynamic dental digital model and the orthodontic appliance digital model. In some embodiments of this application, the maxillary and mandibular models of the dynamic dental digital model can be further subdivided into models of multiple teeth, soft tissue (gingiva and periodontal ligament) models, and jawbone models, and finite element constitutive parameters are set for each of them. The above-described process of pre-assigning finite element constitutive parameters to the digital model is known to those skilled in the art. Tables 1 and 2 below list the preferred value ranges of some finite element constitutive parameters of the dynamic dental digital model and the orthodontic appliance digital model according to some specific embodiments of this application.

[0119] Table 1. Optimal ranges of some finite element constitutive parameters for the dynamic digital dental model.

[0120]

[0121]

[0122] Table 2. Preferred ranges of some finite element constitutive parameters for the orthodontic appliance.

[0123]

[0124] Table 2 shows the range of constitutive parameters for a digital model of an occlusion-inducing orthodontic appliance made of liquid silicone. As mentioned above, the appliance can also be an orthodontic system consisting of a pair of shell-shaped appliances that fit the upper and lower jaws, an arched reinforcing structure connected to the palate of the appliance, and attachments for traction of the bite. The shell-shaped appliances are generally made of resin films by hot pressing. The arched reinforcing structure can be made of metal materials such as medical steel, cobalt-chromium-molybdenum-tungsten, and titanium alloy, or a polymer material with better elasticity than the shell-shaped appliances. The attachments can be made integrally with the shell-shaped appliances using the same material. Obviously, corresponding constitutive parameters can be assigned to the above different structures respectively.

[0125] Step S32 is used to set the finite element calculation parameters. Specifically, the finite element calculation parameters include the contact conditions and boundary conditions between the digital model of the orthodontic appliance and the dynamic digital model of the jaw.

[0126] In some specific embodiments of this application, contact conditions can be set according to the finite element model type of different parts. For example, the contact conditions between the teeth and the occlusion guiding appliance can be set as surface-to-surface or line-to-line contact between a rigid body and a deformable body; or the contact conditions between the gingiva and the occlusion guiding appliance can be set as surface-to-surface or line-to-line contact between deformable bodies. Those skilled in the art can flexibly set the contact conditions according to the constitutive parameters of the jaw model and the appliance model.

[0127] Step S32 is also used to set boundary conditions, such as in some preferred embodiments of this application. Figure 12 As shown, the digital model 600 of the orthodontic appliance can be fixed, fixing five translational / rotational degrees of freedom of the maxillary model 410 of the dynamic dental digital model while releasing only its translational degree of freedom along the Z-axis (vertical direction); fixing four translational / rotational degrees of freedom of the mandibular model 420 of the dynamic dental digital model while releasing its translational degree of freedom along the Z-axis (vertical direction) and its translational degree of freedom along the X-axis (horizontal direction). Under this boundary condition, the maxillary model 410 of the dynamic dental digital model will enter the orthodontic appliance vertically downwards, while the mandibular model 420 will enter the orthodontic appliance with translational movement in the XZ plane without rotation.

[0128] Those skilled in the art can flexibly set boundary conditions according to the actual wearing situation. For example, in some other preferred embodiments of this application, the degrees of freedom of the mandibular model 420 can be further released, such as increasing the degree of freedom of the mandibular model 420 to rotate around the Y-axis with the condyle as the center. The above settings enable the dynamic dental digital model to more accurately reproduce different occlusal processes such as opening and closing the mouth and mandibular protrusion and retraction during finite element simulation.

[0129] In some other preferred embodiments of this application, the degrees of freedom of the mandibular model 420 can be further released, such as increasing the degree of freedom of translation of the mandibular model 420 along the Y-axis. The above settings enable the dynamic dental digital model to more accurately reproduce the lateral occlusion process in the finite element simulation process.

[0130] However, it is understood that releasing the aforementioned multiple degrees of freedom does not mean that the maxillary and mandibular models can move relative to each other without restraint to the extent that they exceed the limits of temporomandibular joint movement or the biomechanical constraints imposed on various parts of the oral cavity. To avoid the aforementioned problems, in the embodiments of this application, the initial values ​​of the wearing parameters can be set in step S33 to further constrain the relative movement of the maxillary model, mandibular model, and orthodontic appliance digital model.

[0131] Specifically, in some preferred embodiments of this application, the wearing parameters include the morphology of the digital model of the orthodontic appliance, the morphology of the dynamic dental digital model, the relative positional relationship between the digital model of the orthodontic appliance and the dynamic dental digital model during wearing, the movement parameters of the condyle during wearing, and the occlusal force of the maxilla and mandible during wearing. The following provides a detailed description of each wearing parameter:

[0132] The morphology of the digital model of the orthodontic appliance and the morphology of the dynamic digital model of the dentition: During the simulation of wearing the orthodontic appliance, the initial values ​​of the morphology of the digital model of the orthodontic appliance and the dynamic digital model of the dentition are their respective three-dimensional morphologies in a relaxed state without stress; as the simulation of wearing the appliance progresses, the various parts of the digital model of the dentition undergo different degrees of strain according to the different properties of the materials assigned to them, and correspondingly generate different degrees of stress. Figures 13A to 13D The morphological changes of the digital model 600 of the orthodontic appliance and the maxillary model 410 and mandibular model 420 of the dynamic dental digital model are shown at different stages of a specific wearing process. In particular, for occlusal induction appliances such as those made of liquid silicone, the morphological changes will significantly affect the final wearing position and the orthodontic force on the teeth and jaws at that position.

[0133] The relative positional relationship between the digital model of the orthodontic appliance and the dynamic digital model of the jaw during the wearing process: The generation of the dynamic digital model of the jaw in step S1 has already introduced the relative positional relationship between the maxilla and mandible in a non-occlusal state and in an occlusal state. These relative positional relationships reflect different occlusal processes when the orthodontic appliance is not worn. Similarly, during the simulation of the jaw wearing the orthodontic appliance, the relative positional relationship between the digital model of the orthodontic appliance and the dynamic digital model of the jaw is constantly changing. Obviously, its initial value can be set as follows: First, the maxillary and mandibular models are positioned according to the relative positional relationship between the maxilla and mandible in a non-occlusal state, and then the digital model of the orthodontic appliance is set between the maxillary and mandibular models.

[0134] Condylar motion parameters during wearing: The condylar motion parameters during wearing (in some embodiments of this application, the condylar motion parameters during wearing include the condylar motion trajectory tilt angle and / or motion trajectory curve during wearing) also have a similar correspondence with the condylar motion parameters during occlusion. That is, the initial value of the condylar motion parameters during wearing can be set to be the same as the condylar motion parameters during occlusion, so that the condylar moves along the same angle or path as the occlusion process without wearing the orthodontic appliance before the upper and lower jaws come into contact with the appliance, and then changes in motion angle and path occur after the upper and lower jaws begin to contact the appliance. Figure 14A , Figure 14B The figures illustrate the different wearing effects resulting from setting different initial values ​​for the motion parameters of the condyle 430 during the wearing process. As can be seen from the figures, when different initial values ​​for the motion parameters are set, the positions of the maxillary dentition included in the maxillary model 410 and the mandibular dentition included in the mandibular model 420 entering the upper alveolar bone 640 and lower alveolar bone 650 of the digital model 600 of the orthodontic appliance differ significantly, further resulting in significantly different force distributions between the maxillary model 410 and the mandibular model 420.

[0135] Occlusal force of the upper and lower jaws during wearing: As analyzed above, the magnitude of occlusal force generated by the upper and lower jaws during different occlusal processes varies. Similarly, using different forces during occlusion while wearing the orthodontic appliance will result in different final appliance placement positions. Specifically, a reasonable range of occlusal force can be set according to the prescription provided by the doctor. For example, for an occlusal induction appliance primarily used for daytime muscle training, the occlusal force during wearing can be set within the muscle training occlusal force range; while for appliances that need to be worn during sleep at night, since multiple unconscious occlusal processes may occur during sleep, setting the occlusal force within the nocturnal bruxism occlusal force range is also acceptable.

[0136] In some preferred embodiments of this application, the biting force of the upper and lower jaws during wear can be acquired by sensors mounted on a dynamic digital dental model. These sensors are virtual sensors capable of simulating real force sensors and are typically placed on multiple teeth. On the surface or the contact surface where occlusion occurs, when a force is applied to the maxillary and mandibular models of the dynamic digital dental model to make them enter the digital model of the orthodontic appliance, the aforementioned sensors can obtain occlusal force information and further adjust the applied force accordingly based on whether it is within an acceptable range.

[0137] After initializing the constitutive parameters, finite element parameters, and wearing parameters of the model through steps S31 to S33, step S34 simulates the wearing process using the finite element method to determine the wearing parameters and the distribution of the orthodontic force at any given moment during the wearing process. In embodiments of this application, the orthodontic force applied by the appliance to various parts of the dentition includes the orthodontic force on at least one tooth, the orthodontic force on the maxilla and / or mandible, and the traction force on the condyle. Correspondingly, the distribution of the orthodontic force specifically includes the magnitude and direction of the orthodontic force on at least one part of the dynamic digital dentition model. In some preferred embodiments of this application, the above-mentioned simulation process and the distribution of the orthodontic force are displayed on a display device, specifically, a desktop or laptop computer screen, a smart tablet, or a smartphone, etc.

[0138] Figures 15A to 15C The simulation results show the distribution of orthodontic forces on the maxillary model 410 of the dynamic digital model of the dentition at different stages of a specific wearing process. Multiple black arrows of different lengths indicate the magnitude and direction of the orthodontic forces on different parts. Similarly, the distribution of orthodontic forces on the mandibular part can also be obtained through finite element simulation. Figure 16 The results of finite element simulations of the traction forces experienced by the condyle at different stages of a specific wearing process are shown.

[0139] In addition, in some embodiments of this application, finite element simulation can not only obtain the magnitude and direction of the orthodontic force on different parts of the dynamic digital model of the teeth and jaws, but also further obtain the torque exerted by the orthodontic appliance on the teeth, jaws and other parts. For example, based on the orthodontic force on a tooth model and combined with the position of the impedance center obtained by measurement or theoretical calculation, the torque applied to the tooth model can be easily determined.

[0140] In some preferred embodiments of this application, the boundary conditions of the finite element calculation parameters set in step S32 also include loading conditions. Specifically, the loading condition can be a loading speed, for example, the loading speed can be set to 0.001 m / s to 3 m / s. By setting the above loading speed conditions, the process of wearing an orthodontic appliance at different occlusal speeds can be simulated. At the same time, appropriately increasing the loading speed can improve the calculation efficiency of simulating the orthodontic appliance wearing process.

[0141] The aforementioned loading speed can also be replaced by other loading conditions that can achieve the same effect. For example, in some embodiments of this application, the loading conditions can be loading displacement, loading rotation, loading force, muscle force, and other loading conditions that can be equivalent to a loading speed of 0.001 m / s to 3 m / s.

[0142] Most existing methods for finite element simulation of the orthodontic effects of orthodontic appliances only perform static analysis of the interaction between teeth and orthodontic appliances, and the finite element calculation methods used are linear calculation methods. In the embodiments of this application, the finite element calculation method uses a nonlinear calculation method to perform dynamic analysis of the process of the appliance being worn onto the jawbone.

[0143] It should be noted that setting loading conditions such as loading speed may cause structural oscillations in the digital model of the orthodontic appliance, resulting in unreasonable changes in the shape of the appliance. Therefore, in some preferred embodiments of this application, the finite element calculation parameters set in step S32 also include damping parameters. Specifically, the damping parameters can be mass damping or other equivalent parameters, and the effective time range of the damping parameters is between 1 and 1000 times the time step of the finite element model. Figure 17 The figure shows a comparison of structural oscillations in the digital model of the orthodontic appliance before and after adding mass damping in a specific embodiment. As can be seen from the figure, adding mass damping can significantly reduce the error in the calculation results caused by structural oscillations.

[0144] The termination condition for the finite element calculation performed in step S33 can be set based on the occlusal force information obtained by the force sensors set on the dynamic dental digital model. For example, in some preferred embodiments of this application, the simulation ends when the occlusal force of the upper and lower jaws during the wearing process is greater than the average value of the maximum occlusal force limit in a human awake state. In other preferred embodiments of this application, other simulation termination conditions can also be set based on the wearing period of the orthodontic appliance provided in the orthodontic plan. For example, the simulation can also end when the occlusal force is greater than the maximum occlusal force during human chewing (or the maximum occlusal force in an unconscious state).

[0145] Furthermore, when setting the termination conditions for finite element analysis (FEM), the changes in wearing parameters during the wearing process can be taken into consideration whether they exceed the limits of human biomechanics or the material limitations of the orthodontic appliance. For example, in some preferred embodiments, the FEM should terminate if the condyle's movement trajectory during wearing exceeds the permissible range of motion of the temporomandibular joint, or if the traction force it experiences exceeds its maximum tolerance. Similarly, the FEM should terminate when the force, torque, or movement of at least one tooth during wearing exceeds its maximum tolerance. Figure 18 The stress-deformation curves and corresponding deformation limits of different orthodontic appliance materials are shown. If the shape of the orthodontic appliance changes beyond the deformation limit of the material used during wear, phenomena such as appliance breakage will occur, and finite element calculations should be stopped at this time.

[0146] The orthodontic force analysis method provided in the embodiments of this application has been described in detail above. In some specific embodiments, those skilled in the art can develop an orthodontic force analysis system based on the above-described orthodontic force analysis method. Specifically, the above-described orthodontic force analysis system may include a memory and a processor, wherein the memory stores a computer program that can run on the processor, and when the processor executes the computer program, it can implement the steps in the above-described orthodontic force analysis method. The specific implementation methods for programming the computer program based on the above-described orthodontic force analysis method with specific steps and the development of the corresponding orthodontic force analysis system are well known to those skilled in the art.

[0147] Another aspect of this application provides a method for optimizing a digital model of an orthodontic appliance, including the following steps:

[0148] Step 1: Based on the above orthodontic force analysis method, determine the distribution of orthodontic force generated by the orthodontic appliance manufactured based on the current digital model of the appliance after it is worn on the upper and lower jaws;

[0149] Step 2: Optimize the current digital model of the orthodontic appliance based on the distribution of orthodontic forces to obtain the optimized digital model of the orthodontic appliance.

[0150] Specifically, in some embodiments, experienced modelers can compare the distribution of orthodontic forces generated at various locations of the jaw after the orthodontic appliance is worn, obtained from finite element simulation, with the expected orthodontic forces in the prescription issued by the dentist. Based on the differences, the morphology, structure, and materials of the digital model of the orthodontic appliance are optimized. The optimized digital model of the orthodontic appliance is then subjected to a new finite element simulation of the wearing process to ensure that the distribution of orthodontic forces generated after the appliance is worn on the patient's jaw matches the expected orthodontic forces. The method of optimizing the digital model of the orthodontic appliance based on the results of finite element simulation is known to those skilled in the art and will not be elaborated upon here.

[0151] Similar to the orthodontic force analysis system described above, in some specific embodiments, those skilled in the art can also develop an orthodontic digital model optimization system based on the aforementioned orthodontic digital model optimization method. Specifically, the aforementioned orthodontic digital model optimization system may include a memory and a processor, wherein the memory stores a computer program that can run on the processor, and when the processor executes the computer program, it can implement the steps in the aforementioned orthodontic digital model optimization method.

[0152] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. An orthodontic force analysis method for analyzing the distribution of orthodontic forces applied by an orthodontic appliance to the teeth to be orthodontized, wherein the orthodontic appliance is designed to traction the temporomandibular joint and nearby muscles to adjust the occlusal relationship of the maxilla and mandible, comprising a U-shaped outer wall and inner wall, and an occlusal pad connecting the inner wall and the outer wall, wherein the inner surface of the upper part of the outer wall, the inner surface of the upper part of the inner wall, and the upper surface of the occlusal pad form an upper alveolar ridge accommodating the maxillary dentition, and the inner surface of the lower part of the outer wall, the inner surface of the lower part of the inner wall, and the lower surface of the occlusal pad form a lower alveolar ridge accommodating the mandibular dentition, characterized in that, Includes the following steps: S1: Obtain a dynamic digital model of the dentition to be treated. The dynamic digital model is generated based on the actual occlusal relationship of the upper and lower jaws and can reproduce the occlusal process of the upper and lower jaws. The actual occlusal relationship includes the movement parameters of the condyle during the occlusal process, specifically including the inclination angle and / or movement trajectory curve of the condyle during the occlusal process. S2: Generate a digital model of the orthodontic appliance based on the dynamic digital model of the jaw; S3: Using the dynamic dental digital model and the orthodontic appliance digital model, the wearing process of the orthodontic appliance is simulated by the finite element method. Based on the simulation, the wearing parameters and the distribution of the orthodontic force at any time during the wearing process are obtained. The wearing parameters include the movement parameters of the condyle during the wearing process, specifically including the tilt angle and / or movement trajectory curve of the condyle during the wearing process. The orthodontic force includes the traction force on the condyle.

2. The orthodontic force analysis method according to claim 1, characterized in that, The orthodontic force also includes at least one of the following corrective forces: Orthodontic force on at least one tooth, orthodontic force on the maxilla and / or mandible.

3. The orthodontic force analysis method according to claim 1, characterized in that, The actual bite relationship also includes: The relative positional relationship between the upper and lower jaws in a non-occlusal state and the relative positional relationship between the upper and lower jaws in an occlusal state.

4. The orthodontic force analysis method according to claim 1, characterized in that, The dynamic dental digital model and the orthodontic appliance digital model are digital finite element models. Step S3 further includes the following steps: S31: Set the finite element constitutive parameters for the dynamic digital model of the jaw and the digital model of the orthodontic appliance; S32: Set finite element calculation parameters; S33: Set the initial values ​​for the wearing parameters; S34: Based on the initial values ​​of the finite element calculation parameters and the wearing parameters, the wearing process is simulated using the finite element calculation method to determine the wearing parameters and the distribution of the orthodontic force at any time during the wearing process.

5. The orthodontic force analysis method according to claim 4, characterized in that, The finite element constitutive parameters include at least one of the following parameters: Material parameters, element parameters, and model type.

6. The orthodontic force analysis method according to claim 4, characterized in that, The wearing parameters also include: The morphology of the digital model of the orthodontic appliance, the morphology of the digital model of the dynamic jaw, the relative positional relationship between the digital model of the orthodontic appliance and the digital model of the dynamic jaw during the wearing process, and the biting force of the upper and lower jaws during the wearing process.

7. The orthodontic force analysis method according to claim 6, characterized in that: The biting force of the upper and lower jaws during the wearing process is obtained by sensors set on the dynamic digital model of the jaw.

8. The orthodontic force analysis method according to claim 6, characterized in that: The simulation ends when the biting force of the upper and lower jaws during the wearing process exceeds the average value of the maximum biting force limit of a human in a waking state.

9. The orthodontic force analysis method according to claim 4, characterized in that: The finite element method described uses a nonlinear calculation method.

10. The orthodontic force analysis method according to claim 9, characterized in that, The finite element calculation parameters include: Contact and boundary conditions between the digital model of the orthodontic appliance and the dynamic digital model of the jaw.

11. The orthodontic force analysis method according to claim 10, characterized in that: The boundary conditions include the loading speed.

12. The orthodontic force analysis method according to claim 11, characterized in that: The loading speed is 0.001 m / s to 3 m / s; The finite element calculation parameters also include damping parameters.

13. The orthodontic force analysis method according to claim 1, characterized in that: The distribution of orthodontic forces includes the magnitude and direction of orthodontic forces acting on at least one part of the dynamic digital model of the jaw.

14. The orthodontic force analysis method according to claim 1, characterized in that: It also includes the step of displaying the simulation process and the distribution of orthodontic forces on a display device.

15. The orthodontic force analysis method according to claim 1, characterized in that: The orthodontic appliance is used to align teeth, adjust the dental arch shape of the maxilla and / or mandible, and adjust the occlusal relationship between the maxilla and mandible.

16. The orthodontic force analysis method according to claim 1, characterized in that: The actual occlusal relationship is obtained by measuring the teeth to be treated using an articulator.

17. A method for optimizing a digital model of an orthodontic appliance, characterized in that, Includes the following steps: Step 1: Determine the distribution of orthodontic forces generated by the orthodontic appliance manufactured based on the current digital model of the appliance after it is worn on the upper and lower jaws, based on the orthodontic force analysis method according to any one of claims 1 to 16. Step 2: Optimize the current digital model of the orthodontic appliance based on the distribution of orthodontic forces to obtain the optimized digital model of the orthodontic appliance.

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