Simulation device, program, and simulation method

Abstract

To provide a simulation device having a load for calculation processing lighter than conventional techniques to enable accurate simulation, a program for simulation, and a simulation method.SOLUTION: A simulation device 1 for using an aligner to predict tooth movement in performing orthodontic treatment of teeth of a patient is provided with a movement calculation part 13 for calculating an arrangement state of a prescribed tooth on the basis of teeth information of the patient and aligner information, the movement calculation part 13 calculates the arrangement state on the basis of orthodontic force of the aligner and the magnitude of a load generated by a peripheral tissue of the prescribed tooth, and the movement calculation part 13 calculates the magnitude of the load by using an attenuation model that attenuates according to a prescribed characteristic as time passes and calculates the arrangement state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a simulation device, a program, and a simulation method for orthodontic treatment using aligners. [Background technology]

[0002] In recent years, orthodontic treatment using aligners has become common. In this orthodontic treatment, patients wear aligners, which are individually tailored to their individual needs, according to a pre-set plan, to straighten their teeth. An aligner is a mouthpiece-shaped orthodontic appliance made from a material with a certain degree of elasticity. When worn by a patient, the aligner is designed so that the portions of the aligner that correspond to the teeth requiring correction (the teeth to be corrected) are stretched at a certain rate. Therefore, when a patient wears the aligner, a force is applied to the teeth to be corrected, causing the stretched portions of the aligner to return to their original position. This force straightens the teeth.

[0003] Because there is a limit to the distance that a single aligner can move teeth, multiple aligners are used in actual orthodontic treatment. That is, orthodontic treatment is performed by having the patient wear multiple pre-made aligners in a predetermined order.

[0004] Aligners are generally made from soft materials, so patients experience less discomfort than with traditional orthodontic treatments using brackets and wires.Also, because aligners are made from transparent resins, they are said to be more aesthetically pleasing than traditional orthodontic treatments using brackets and wires.

[0005] On the other hand, if the aligner design is inappropriate, the teeth to be orthodontic treated may move to a position different from the ideal position or may be tilted more than ideally. Furthermore, because orthodontic treatment takes a long time to complete, it is difficult to determine whether the aligner design is appropriate before starting orthodontic treatment. For this reason, as shown in Patent Document 1, for example, computer simulations are performed to confirm the effects of orthodontic treatment in advance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4827375 Summary of the Invention [Problem to be solved by the invention]

[0007] The technology described in Patent Document 1 requires complex calculations such as finite element analysis to analyze the interaction of forces acting between orthodontic appliances and teeth, which requires a CPU with high computing power and also requires a huge amount of time to perform the necessary calculations.

[0008] On the other hand, in order to improve processing speed, simulations based on simple theories are also performed. For example, simulations are performed using simple calculations, assuming that the teeth to be orthodontic treated move translationally due to an external force. However, while such simulations can improve processing speed, the results may be inaccurate. In other words, there is a possibility that the analysis process may not properly reflect the actual movement of the teeth during orthodontic treatment.

[0009] The present disclosure discloses an example of an orthodontic treatment simulation device, program, and simulation method that reduces the load for calculation processing and enables accurate analysis processing compared to conventional techniques that use calculation processing such as complex finite element analysis. [Means for solving the problem]

[0010] To achieve the above object, the present disclosure provides the following means. The simulation device disclosed herein predicts the movement of a patient's teeth when undergoing orthodontic treatment using aligners. The simulation device disclosed herein includes a movement calculation unit that calculates a positional state indicating the position and posture of a specific tooth after orthodontic treatment based on the patient's tooth information and aligner information. The tooth information includes at least information regarding the shape of each of the patient's teeth, information indicating the arrangement of the patient's teeth before orthodontic treatment, and information regarding the tissues surrounding the patient's teeth. The aligner information includes at least information regarding the shape and physical properties of the aligner. The movement calculation unit then calculates the positional state based on the orthodontic force applied to the specific tooth by the aligner and the magnitude of the load generated by the tissues surrounding the specific tooth when the orthodontic force is applied to the specific tooth. In this case, the movement calculation unit calculates the positional state using an attenuation model in which the magnitude of the load attenuates over time according to a predetermined characteristic.

[0011] The above configuration enables accurate simulations that take into account the characteristics of the tissues surrounding the teeth. In other words, the simulation device of the present disclosure can accurately predict the movement of specified teeth due to orthodontic treatment and the alignment of teeth after orthodontic treatment, taking into account the characteristics of the tissues surrounding the teeth, without performing complex calculations as in conventional techniques.

[0012] In the above disclosure, the damping model is preferably a mathematical model based on the creep phenomenon of a specific material, which allows accurate prediction of the tooth alignment after orthodontic treatment by calculating the magnitude of the load taking into account the characteristics of the actual surrounding tissue without complex calculations.

[0013] In the above disclosure, the movement calculation unit preferably calculates the positioning state based on the tooth information and the aligner information using a simplified model in which the aligner, the patient's teeth, and the surrounding tissues of the teeth are each represented by a plurality of beam elements having a beam-like shape. Each of the beam elements constituting this simplified model preferably corresponds to a portion of the aligner, the teeth, or the surrounding tissues of the teeth, and the movement calculation unit preferably calculates the positioning state assuming that each beam element has bending stiffness and torsional stiffness corresponding to the physical properties of the corresponding portion.

[0014] This configuration allows the aligner, teeth, and surrounding tissues to be represented by simple models, reducing the computational load required for analysis processing when performing simulations that take into account the interactions between them. In other words, accurate simulations that reflect the characteristics of each part can be performed at improved processing speed.

[0015] In the above disclosure, when a tooth has an attachment used for orthodontic treatment, it is preferable that the movement calculation unit calculates the positioning state by setting the torsional stiffness of the beam element corresponding to the part of the aligner related to the tooth on which the attachment is attached to a value greater than when no attachment is attached to the tooth to be orthodontic treatment.

[0016] With the above configuration, a simulation that appropriately reflects the characteristics when an attachment is provided on a specific tooth can be performed without performing any additional processes.

[0017] Furthermore, the present disclosure also includes a program for operating an electronic computing device (computer) as the above-mentioned simulation device, and a simulation method for performing similar processing. [Effects of the Invention]

[0018] The simulation device, program, and simulation method disclosed herein can perform accurate simulations that reflect the characteristics of each part, at processing speeds faster than conventional techniques. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a block diagram illustrating a simulation device according to the present disclosure. [Figure 2] FIG. 2 is a block diagram illustrating functions of the simulation device of the present disclosure. [Figure 3] Figure 3(a) is a schematic diagram illustrating the forces acting on the teeth, and Figure 3(b) is a schematic diagram illustrating the teeth and aligners. [Figure 4] FIG. 1 is a diagram illustrating an example of a mathematical model (corrective force calculation model) showing the relationship between corrective force and the amount of change in the aligner. [Figure 5] FIG. 1 is a diagram illustrating an example of a mathematical model (attenuation model) showing how the load applied to the tissues surrounding a tooth changes over time. [Figure 6] FIG. 1 is a diagram illustrating an example of a simple model. [Figure 7] FIG. 10 is a flow diagram illustrating an example of a processing flow. [Figure 8] FIG. 1 is a diagram (STL image) for explaining an example of the arrangement of teeth before orthodontic treatment. [Figure 9] FIG. 1 is a diagram illustrating a predetermined ideal tooth arrangement. [Figure 10] FIG. 1 is a diagram illustrating an example of a simple model. [Figure 11] FIG. 10 is a diagram illustrating an example of a three-dimensional image showing the result after the analysis process. DETAILED DESCRIPTION OF THE INVENTION

[0020] The simulation device 1 of the present disclosure will be described mainly with reference to FIGS. 1 to 7. In the following description, the front-rear, left-right, and up-down directions will refer to the directions shown in the drawings unless otherwise specified. The oral cavity side of the patient's teeth will be referred to as the inside, and the opposite side (labial side or cheek side) (oral vestibule side) will be referred to as the outside. The outward-facing surface of the patient's teeth will also be referred to as the outer surface or vestibular surface, and the oral cavity side of the patient's teeth will also be referred to as the inner surface or oral surface. The surface of the teeth that comes into contact with the opposing tooth when the teeth are occluded (the surface on which food is chewed) will also be referred to as the occlusal surface.

[0021] 1. Description of the configuration First, the configuration of the simulation device 1 will be described. The simulation device 1 is a general-purpose computer (electronic computing device) on which dedicated software (program) is installed. The simulation device 1 mainly comprises a computer main body 10, an input device 3, and a display / output device 4 (see FIG. 1). The simulation device 1 may further comprise additional components different from those described above.

[0022] The computer main body 10 includes components typically found in general-purpose computers and server devices, such as a CPU 5, memory 6 such as RAM and ROM, and an interface unit 7. Examples of the interface unit 7 include a communication interface and an input / output device interface. The computer main body 10 also includes a storage unit 2, which is a general-purpose storage device such as a hard disk or SSD. The storage unit 2 may be built into the computer main body 10 or may be external. Alternatively, the storage unit 2 may be a storage device accessible to a network to which the computer main body 10 is connected, or a storage device included in another computer or server device connected to the same network. The storage unit 2 may also be a combination of multiple storage devices. The configuration of the computer main body 10 is not limited to the above, as long as it can implement the functions described below.

[0023] The input device 3 is a device such as a mouse or keyboard that is operated by a user. The display / output device 4 is an output device that outputs in response to an output signal from the computer main body 10. Examples of the display / output device 4 include a display device such as an LCD display, a printer, etc., but are not particularly limited thereto.

[0024] The simulation device 1 reads out a dedicated program installed in the memory unit 2 etc., and operates in cooperation with hardware such as the CPU 5, memory 6, and interface unit 7, thereby realizing the functions of each unit, the details of which will be described below.

[0025] More specifically, the simulation device 1 realizes the functions of the information acquisition unit 11, array calculation unit 12, movement calculation unit 13, and display signal output unit 14 by the cooperation of a dedicated program and hardware constituting a computer. In other words, the simulation device 1 includes the information acquisition unit 11, array calculation unit 12, movement calculation unit 13, and display signal output unit 14 (see FIG. 2). The functions of each unit will be described in detail later. The simulation device 1 may also be configured from dedicated hardware that has the functions of each unit described below.

[0026] The information acquisition unit 11 has a function of acquiring information on tooth morphology, information on the morphology of the surrounding tissues, information on the characteristics of the tissues, etc. from three-dimensional information of the patient acquired by an X-ray CT device, etc. Hereinafter, information including at least information on the patient's teeth and surrounding tissues acquired by the information acquisition unit 11 will also be referred to as "tooth information."

[0027] The tooth information includes at least information about the shape of each of the patient's teeth and information indicating the patient's tooth alignment (tooth arrangement) before orthodontic treatment. For example, it includes at least information about the three-dimensional shape of the crown and root of each tooth in the patient's upper and lower dentition, information about the position and posture (inclination) of each tooth, and information indicating the arrangement of each tooth.

[0028] The tooth information also includes information about the tissues surrounding the teeth. The tissues surrounding the teeth include the gums, alveolar bone, and periodontal ligament. In the following description, the tissues surrounding the patient's teeth will also be referred to as "tissues surrounding the teeth" or simply "surrounding tissues."

[0029] Information about the tissues surrounding the teeth includes, for example, information indicating the shape of the alveolar bone and the distance between the alveolar bone and the corresponding tooth (thickness of tissues such as the periodontal ligament). Information about the tissues surrounding the teeth also includes information indicating their characteristics. An example of information indicating the characteristics of the surrounding tissues is the patient's bone density, but information indicating other physical or physiological characteristics of the tissues surrounding the teeth may also be included.

[0030] If a specific tooth has an attachment, the tooth information also includes information about the attachment, such as the position of the tooth on which the attachment is attached and the shape of the attachment. Details of tooth attachments will be described later.

[0031] The information acquisition unit 11 acquires information obtained by converting three-dimensional information about the morphology of teeth and their surrounding tissues, which is included in the acquired tooth information, into versatile data in a predetermined format. An example of this versatile data is STL data. The information acquisition unit 11 may also acquire information converted into data in other formats. Hereinafter, the data converted by the information acquisition unit 11 will also be referred to as "STL information." The tooth information acquired by the information acquisition unit 11 and the converted STL information are stored in the memory unit 2. The information acquisition unit 11 may also have a function to convert information acquired by an X-ray CT scanner or the like into versatile data such as STL information. Furthermore, the information acquisition unit 11 also has a function to acquire information about the patient and information about the aligner based on information input by the user using the input device 3 or the like. Examples of patient information include information about the patient's bone density and information about the patient's age. Examples of aligner information include information about the aligner's material (quality).

[0032] The array calculation unit 12, the movement calculation unit 13, and the display signal output unit 14 are parts that mainly perform analysis processing for simulation and output processing of the results. The array calculation unit 12 functions as a preprocessor for the analysis processing.

[0033] The arrangement calculation unit 12 has a function to generate three-dimensional information showing the ideal state of tooth alignment after orthodontic treatment according to the operation by the user. Specifically, it has a function to create three-dimensional information (information showing the ideal tooth alignment) showing the state in which the patient's teeth are aligned in the ideal state, which is set by the user operating the input device 3 or the like.

[0034] Furthermore, the array calculation unit 12 has a function to generate information about the aligners used in orthodontic treatment. The information about the aligners includes information about the dimensions of the aligners required for analysis processing. This information about the dimensions of the aligners includes at least the dimensions of each part of the aligner and information about the deformation rate of the aligners when orthodontic treatment is performed.

[0035] Specifically, the array calculation unit 12 has a function to calculate information about the dimensions of each part of the aligner corresponding to the patient's teeth based on information about the morphology of the teeth and other information included in the patient's tooth information and information indicating the ideal tooth alignment state set by the user. The array calculation unit 12 also has a function to calculate, as one piece of information about the aligner dimensions, the degree to which the aligner needs to be deformed (stretched) from its original state in order to move the teeth to be corrected to the ideal positions set by the user. As described above, in orthodontic treatment using aligners, when the patient wears the aligner, the parts of the aligner corresponding to the teeth to be corrected are stretched (deformed), and the force of these parts trying to return to their original state causes tooth correction. In other words, the movement distance (orthodontic movement distance) required to move the teeth to be corrected to the ideal positions corresponds to the amount of deformation (stretched length) of the aligner for orthodontic treatment. For this reason, the arrangement calculation unit 12 calculates the distance of movement (orthodontic movement distance) required to move the teeth to the ideal position based on information indicating the ideal tooth arrangement state set by the user and information indicating the tooth arrangement state before orthodontic treatment.Then, the calculated orthodontic movement distance is stored in the memory unit 2 as the amount of deformation of the aligner during orthodontic treatment.

[0036] Because the distance that a single aligner can move the teeth to be corrected is limited, multiple aligners are used in actual orthodontic treatment. In other words, the amount of deformation of an aligner during orthodontic treatment is the sum of the deformations (stretched lengths) of each aligner used in orthodontic treatment. In other words, the orthodontic movement distance is equivalent to the sum of the deformations (stretched lengths) of each aligner used in orthodontic treatment.

[0037] The array calculation unit 12 also has a function to calculate the number of aligners required for orthodontic treatment. As mentioned above, the distance that a single aligner can move a tooth to be orthodontic treated is limited. Therefore, the array calculation unit 12 has a function to calculate the number of aligners required for orthodontic treatment based on the distance required to move the tooth to its ideal position and the distance that a single aligner can move the tooth to be orthodontic treated.

[0038] Furthermore, the array calculation unit 12 has the function of calculating the force that the teeth to be orthodontic treated will receive from the aligners during orthodontic treatment. Hereinafter, the force that the patient's teeth receive from the aligners, in other words, the force that the aligners exert on a specific tooth, will also be referred to as the "orthodontic force." The array calculation unit 12 calculates the magnitude of the orthodontic force using an orthodontic force calculation model, the details of which will be described later, based on information about the dimensions and physical properties of the aligners.

[0039] Information about the physical properties of the aligner is information that indicates the physical characteristics of the material that makes up the aligner, including, for example, the bending rigidity and torsional rigidity of the material that makes up the aligner.

[0040] In the following description, the information about the aligners described above will also be referred to as "aligner information." That is, information about the aligners used in a patient's orthodontic treatment, such as information about the aligner's dimensions and physical properties, will also be collectively referred to as "aligner information."

[0041] Furthermore, the array calculation unit 12 has the function of creating a simplified model in which the patient's teeth, surrounding tissues, and aligners are represented in shapes simpler than their actual shapes. Specifically, the array calculation unit 12 has the function of creating a simplified model in which the teeth, surrounding tissues, and aligners are represented by multiple beam elements, each with a beam-like shape, based on the tooth information and aligner information. The simplified model will be described in detail later.

[0042] The movement calculation unit 13 analyzes the forces acting on specific teeth of a patient during orthodontic treatment using aligners and calculates the movement of the teeth due to the aligner-based orthodontic treatment. In other words, the movement calculation unit 13 analyzes the forces acting on each of the patient's teeth affected by the attached aligner and calculates the movement of each tooth. Referring to FIG. 3(a), when a patient generally wears an aligner 26, the crown portion 20a to which the aligner 26 is attached receives an orthodontic force F from the aligner 26 in a direction that causes the stretched portion of the aligner 26 to return to its original position. Meanwhile, the root portion 20b is surrounded by surrounding tissues, such as the gums 23, periodontal ligament 24, and alveolar bone 25. Therefore, when the orthodontic force F is applied to the root portion 20b, the root portion 20b receives a force (load R) from the surrounding tissues in a direction opposite to the direction of the orthodontic force F (see FIG. 3(a)).

[0043] It is known that the magnitude of the load R (resistance) that a tooth receives from its surrounding tissues decreases over time when a force is applied in a predetermined direction. The movement calculation unit 13 has a function to calculate the magnitude of this load R using a damping model that decreases over time according to a predetermined characteristic. The damping model will be described in detail later.

[0044] The movement calculation unit 13 also has a function to calculate the position and posture (inclination) of each tooth after orthodontic treatment using the simple model created by the arrangement calculation unit 12, the orthodontic force from the aligner, and the attenuation model. Hereinafter, the state indicating the position and posture of a specific tooth will also be referred to as the "arrangement state." The movement calculation unit 13 also has a function to create information indicating the tooth alignment (tooth arrangement state) at that time based on the calculated arrangement state of each tooth.

[0045] The display signal output unit 14 performs post-processing in the analysis process and has the function of generating a three-dimensional image based on the STL information converted by the information acquisition unit 11 and the analysis results calculated by the movement calculation unit 13. Hereinafter, an image generated based on the STL information will also be referred to as an "STL image." That is, the display signal output unit 14 has the function of generating three-dimensional image information showing the arrangement of each tooth based on the STL information stored in the memory unit 2 and the analysis results performed by the movement calculation unit 13. The three-dimensional image information generated by the display signal output unit 14 is output to the display / output device 4. Hereinafter, a three-dimensional image showing the state of the patient's teeth before orthodontic treatment will also be referred to as a "three-dimensional image before orthodontic treatment." Furthermore, a three-dimensional image showing the state of ideal teeth alignment set according to user operations will also be referred to as a "three-dimensional image of ideal teeth alignment."

[0046] The memory unit 2 is a section that stores information required for the simulation. A dedicated program for performing the simulation is stored in the memory unit 2. The memory unit 2 also stores patient tooth information, STL information, information regarding the ideal arrangement of the patient's teeth set by the user, information calculated by the movement calculation unit 13, and the like.

[0047] The storage unit 2 also stores information about the physical properties of aligners. Specifically, information about the physical properties of materials commonly used to form aligners is stored, linked to information indicating the name and type of the material. The storage unit 2 also stores information about an orthodontic force calculation model and an attenuation model, which will be described in detail later.

[0048] 2. Orthodontic force calculation model Because aligners are made of elastic material, when they are stretched or otherwise deformed, a force is generated that tries to return them to their original state. The magnitude of this force varies depending on the degree of deformation of the aligner. In other words, aligners have the characteristic that when the degree of deformation is large, a large force (corrective force) is generated, and as the degree of deformation decreases, the magnitude of this force decreases. Here, the degree of deformation is information (amount of change) that indicates how much the shape of the aligner has deformed from its original state.

[0049] The simulation device 1 calculates the orthodontic force based on the above-mentioned aligner characteristics. Specifically, as shown in FIG. 4, the simulation device 1 calculates the magnitude of the orthodontic force generated when the aligner is worn using an orthodontic force calculation model, which is a mathematical model that represents the relationship between the aligner's deformation rate (amount of change) and the orthodontic force (the force that attempts to return to its original state from the deformed state). Based on the aligner information and tooth information, the simulation device 1 calculates the aligner's deformation rate when a specific aligner is worn on a patient. Then, based on the calculated deformation rate, the simulation device 1 refers to the corresponding orthodontic force calculation model and calculates the orthodontic force.

[0050] Because the relationship between the aligner's deformation rate (amount of change) and the orthodontic force varies depending on the aligner's material, the memory unit 2 stores multiple orthodontic force calculation models corresponding to the aligner's material (see Figure 4). Figure 4 shows three orthodontic force calculation models M1, M2, and M3, each with different characteristics depending on the aligner's material. That is, one of the orthodontic force calculation models M1, M2, or M3 is selected based on information about the aligner's material entered by the patient, and the orthodontic force is calculated. Note that Figure 4 is merely an example, and the number of orthodontic force calculation models and their characteristics are not limited to those shown in Figure 4.

[0051] 3. Attenuation model As mentioned above, when an orthodontic force is applied to a tooth, the magnitude of the load R (resistance) that the tooth receives from the surrounding tissues is known to decrease (decay) over time according to a specific characteristic. This is said to be because the tissue on the side of the alveolar bone surrounding the root that receives the orthodontic force (tissue in area P surrounded by the dashed line in Figure 3(a)) dies due to the pressure caused by the reaction force of the load R received by the tooth, while the tissue on the opposite side (tissue in area Q surrounded by the dashed line in Figure 3(a)) grows. For this reason, it is known that the magnitude of the load (resistance) that a tooth receives from the surrounding tissues when an orthodontic force is applied generally decreases (decays) according to the same characteristic (tendency) for any patient.

[0052] The simulation device 1 calculates the magnitude of the load (resistance) at a predetermined time using a damping model (see FIG. 5), which is a mathematical model that represents the decrease in load according to a predetermined characteristic over time. The predetermined characteristic is the characteristic shown in FIG. 5, in which the magnitude of the load decreases at a large rate over an initial period, then the rate of decrease gradually becomes gentler, and then decreases more gradually. The movement calculation unit 13 performs processing to refer to the damping model based on the time that has passed since the aligner was attached, and calculates the magnitude of the load (resistance) that the tooth receiving the orthodontic force experiences from the surrounding tissues.

[0053] This attenuation model is a mathematical model created by focusing on the results of physical experiments using multiple clinical models and the analytical data, which showed that the characteristics of the surrounding tissues when an orthodontic force is applied to a patient's teeth are similar to the creep characteristics of a specific material. In other words, this attenuation model is a mathematical model created by focusing on the fact that the characteristics based on physiological phenomena that occur in the surrounding tissues, such as the alveolar bone, when an orthodontic force is applied to a patient's teeth have characteristics similar to the creep characteristics of a physical phenomenon. Here, the "specific material" refers to any material that exhibits creep characteristics similar to the characteristics based on physiological phenomena that occur in the surrounding tissues, and it may be a material different from or the same as the material contained in the composition of the tissues surrounding the patient's teeth.

[0054] The attenuation model is created based on the results of physical experiments using clinical models that reflect the characteristics of actual tissues and the analysis data, so that it has the same characteristics as the phenomena that occur in actual surrounding tissues such as alveolar bone. The clinical model used in this physical experiment is a model created based on multiple clinical data (dental information) obtained from multiple patients and subjects, and reflects the physical characteristics of human teeth and their surrounding tissues. It has been confirmed that the attenuation model can obtain results that are very similar to the results of physical experiments using clinical models.

[0055] It is known that the magnitude of the load (resistance) a tooth receives from surrounding tissues when an orthodontic force is applied, and the attenuation characteristics of that load (resistance), vary depending on the condition of the surrounding tissues. For example, it is known that the characteristics of the load (resistance) received from surrounding tissues vary depending on the patient's bone density, age, and other factors. For this reason, the memory unit 2 stores multiple attenuation models corresponding to patient information such as the patient's age and bone density. Figure 5 shows three attenuation models m1, m2, and m3 with different characteristics corresponding to the patient's bone density. That is, attenuation models m1, m2, and m3 are selected based on patient information such as bone density input by the user, and the magnitude of the load (resistance) received from surrounding tissues is calculated. It is noted that Figure 5 is an example, and the number of attenuation models and their characteristics are not limited to those shown in Figure 5.

[0056] 4. About the simple model The simplified model used in the analysis process will be described below. The simplified model used in the simulation device 1 of the present disclosure is a model in which the patient's teeth, their surrounding tissues, and the aligner are represented by multiple beam elements with a beam-like shape. The array calculation unit 12 divides the patient's teeth, surrounding tissues, aligner, and other parts according to predetermined conditions and generates beam elements corresponding to each divided part. Specifically, the array calculation unit 12 generates beam elements corresponding to the divided parts based on tooth information and aligner information. The array calculation unit 12 then generates a simplified model in which each divided part is replaced with the generated beam elements. In other words, the array calculation unit 12 generates a simplified model that reflects information about the dimensions of each part of the actual teeth, surrounding tissues, and aligner, as well as information about the physical properties of each part.

[0057] Hereinafter, the simplified model will be described in detail, mainly with reference to Figures 3(b) and 6. Figure 3(b) shows two adjacent teeth 30, 40 on the patient's maxillary side, tissue 60 surrounding the teeth 30, 40, and an aligner portion 50P, which is a part of an aligner 50 used in orthodontic treatment. To specifically describe the aligner portion 50P, the aligner portion 50P is a portion of the aligner 50 that covers approximately half of each of the outer surface, inner surface, and occlusal surface of the tooth 30 (approximately half of the area on the tooth 40 side), as well as approximately half of each of the outer surface, inner surface, and occlusal surface of the tooth 40 (approximately half of the area on the tooth 30 side). The shaded area in Figure 3(b) is the aligner portion 50P.

[0058] Hereinafter, the approximately half area of ​​each of the two adjacent teeth as described above will be collectively referred to as the "section between the two teeth." For example, the portion of tooth 30 facing tooth 40 and the portion of tooth 40 facing tooth 30, whose occlusal surfaces are covered by aligner part 50P, will be collectively referred to as the "section between teeth 30 and 40."

[0059] Figure 6 shows the simplified model 100 corresponding to Figure 3(b). In Figure 6, the positive direction of the X-axis corresponds to the direction outward from the patient's oral cavity, and the negative direction of the X-axis corresponds to the direction inward.

[0060] In the simplified model 100, the tooth 30 is represented by a beam portion 30A in which beam elements 31a and 31b are linearly connected at node 33. Beam element 31a is the portion indicated by the two-dot chain line connecting node 32 and node 33 in FIG. 6, and beam element 31b is the portion indicated by the two-dot chain line connecting node 33 and node 34. Beam element 31a corresponds to the crown portion of the tooth 30, and beam element 31b corresponds to the root portion of the tooth 30. Similarly, the tooth 40 is represented by a beam portion 40A in which beam elements 41a and 41b are linearly connected at node 43. Beam element 41a is the portion indicated by the two-dot chain line connecting node 42 and node 43, and beam element 41b is the portion indicated by the two-dot chain line connecting node 43 and node 44.

[0061] In the simplified model 100, the aligner part 50P covering the section between the teeth 30 and 40 is represented by four beam elements 51f, 51r, 52f, and 52r. Beam elements 51f and 52f correspond to the portions located on the outer surfaces of the teeth 30 and 40. Beam elements 51r and 52r correspond to the portions located on the inner surfaces of the teeth 30 and 40. Beam elements 51f and 51r correspond to the portions located on the occlusal surface side of the section between the teeth 30 and 40, and beam elements 52f and 52r correspond to the portions located on the gum side of the section between the teeth 30 and 40.

[0062] The number of beam elements representing the aligner portion 50P may be any number other than four, as long as it is two or more. For example, it may be represented by two or three beam elements, or by five or more beam elements.

[0063] In the simplified model 100, node 32 corresponds to the portion of the occlusal surface of tooth 30 that protrudes most inwardly or outwardly from the root. Node 35 corresponds to the portion of the inner or outer surface of tooth 30 that protrudes most inwardly or outwardly. The same is true for nodes 42 and 45. Furthermore, beam elements 53f to 56f and beam elements 53r to 56r represent the crown portions of tooth 30, respectively.

[0064] In the simplified model 100, node 33 corresponds to the boundary between the crown and gum of tooth 30. Node 34 corresponds to the end of the root of tooth 30 that is far from the occlusal surface. Nodes 43 and 44 also correspond to the respective parts of tooth 40.

[0065] In the simplified model 100, surrounding tissue 60 such as alveolar bone that surrounds the periphery of the root portion of tooth 30 is represented by beam elements 36x, 36y, 36z and beam elements 37x, 37y, 37z. Beam elements 36x, 36y, 36z correspond to the tissue of surrounding tissue 60 of tooth 30 that is closer to the crown portion of tooth 30. Beam elements 37x, 37y, 37z correspond to the tissue of surrounding tissue 60 of tooth 30 that is farther from the crown portion of tooth 30. Similarly, surrounding tissue 60 that surrounds the periphery of the root portion of tooth 40 is represented by beam elements 46x, 46y, 46z and beam elements 47x, 47y, 47z.

[0066] Beam elements 36x, 36y, and 36z extend in the same directions as the X, Y, and Z axes of the reference coordinate system of the simplified model. That is, beam element 36x extends in the same direction as the X axis, beam element 36y extends in the same direction as the Y axis, and beam element 36z extends in the same direction as the Z axis. That is, beam element 36x represents the characteristics of the tissue 60 surrounding tooth 30 in the X axis direction, beam element 36y represents the characteristics of the tissue 60 surrounding tooth 30 in the Y axis direction, and beam element 36z represents the characteristics of the tissue 60 surrounding tooth 30 in the Z axis direction. The same applies to beam elements 37x to 37z, beam elements 46x to 46z, and beam elements 47x to 47z. Hereinafter, beam elements 36x to 36z will also be collectively referred to as beam portion 36. Similarly, beam elements 37x to 37z, beam elements 46x to 46z, and beam elements 47x to 47z are also referred to as beam portion 37, beam portion 46, and beam portion 47. In this way, by representing surrounding tissue 60 with a plurality of beam elements extending in the same directions as the X, Y, and Z axes of the reference coordinates of the simple model, a model is obtained in which the characteristics of surrounding tissue 60 are appropriately reflected.

[0067] The array calculation unit 12 expresses the length of each beam element as a length corresponding to the actual length of the corresponding portion, in principle. For example, in the simplified model 100, beam element 31a and beam element 31b are expressed as lengths corresponding to the actual lengths of the crown and root of tooth 30, respectively. On the other hand, the length of the beam element may be optimized (modified) so that the actual characteristics of the corresponding portion are accurately reflected and appropriate analysis is performed. Furthermore, the length of the beam element representing the surrounding tissue 60 is set according to the characteristics of the surrounding tissue 60. For example, the lengths of beam elements 36x, 36y, 36z and beam elements 37x, 37y, 37z are each set to a length that appropriately expresses the components of the reference axis directions (X, Y, and Z directions) of the load generated when an orthodontic force is applied to tooth 30.

[0068] In the simplified model 100, each beam element is set with a characteristic corresponding to the physical properties of the corresponding portion. These characteristics include bending rigidity and torsional rigidity corresponding to the physical properties of the corresponding portion. For example, beam elements 51f-52r representing the aligner portion 50P are set with a characteristic corresponding to the physical properties of the portion of the aligner portion 50P to which each beam element corresponds. To explain using an example, beam element 51f is set with a characteristic such as bending rigidity or torsional rigidity corresponding to the physical properties of the portion of the aligner portion 50P that covers the occlusal side of the outer surfaces of teeth 30 and 40. Similarly, beam elements 51r, 52f, and 52r are set with a characteristic such as bending rigidity or torsional rigidity corresponding to the physical properties of the portion of the aligner portion 50P to which each beam element corresponds.

[0069] Similarly, characteristics corresponding to the physical properties of the corresponding portions are set for the other beam elements. That is, because beam elements 31a, 31b, 41a, 41b and beam elements 53f-56r correspond to teeth 30, 40, which are rigid bodies, the characteristics of rigid bodies are set for each of them. Furthermore, beam elements 36x-37z and beam elements 46x-47z reflect characteristics estimated from the characteristics of surrounding tissue 60, such as the shape of the alveolar bone, the distance between teeth 30, 40 and alveolar bone (such as the thickness of the periodontal ligament), and bone density. That is, the component in the reference axis direction of the characteristics of surrounding tissue 60 obtained based on tooth information is assigned to the corresponding beam element and set.

[0070] <When attachments are attached to specific teeth> If the patient's teeth have attachments for fixing the aligners, the array calculation unit 12 sets the torsional stiffness of the beam elements corresponding to the portions of the aligner associated with the teeth with the attachments to a value greater than that when the attachments are not present. Here, the portions of the aligner associated with the teeth with the attachments refer to the portions of the aligner that are mechanically affected by the presence of the attachments. For example, the portions of the aligner that cover the space between the tooth with the attachment and the adjacent tooth, or the portions of the aligner within a certain distance from the tooth with the attachment.

[0071] If a patient's teeth have attachments, the corresponding portions of the aligner fit into the attachments and are fixed in place, making the aligner less likely to slip or twist. Therefore, when a patient's teeth have attachments, the array calculation unit 12 assumes that an aligner that is less prone to twisting than normal is attached to that portion, and sets the torsional stiffness of the beam element corresponding to the portion of the aligner associated with that tooth to a larger value. In other words, the array calculation unit 12 performs processing to set the torsional stiffness of that beam element to a larger value than when no attachments are attached. By performing this processing, the array calculation unit 12 can easily reflect the characteristics of the attachments in the simplified model.

[0072] 5.Analysis processing using a simple model (simulation) The following describes the analytical process performed by the movement calculation unit 13 using the simplified model. As described above, the movement calculation unit 13 analyzes the forces applied to each of the patient's teeth during orthodontic treatment using aligners and calculates the movement of the patient's teeth during the orthodontic treatment period. When performing this process, the movement calculation unit 13 applies the orthodontic force calculation model and attenuation model described above to the simplified model to perform the analytical process. Specifically, with reference to FIG. 6 , the movement calculation unit 13 applies the orthodontic force calculation model to each beam element corresponding to the aligner portion 50P of the simplified model 100, and calculates the force generated by each beam element based on the deformation rate generated in each portion of the aligner portion 50P to perform the analytical process. For example, the movement calculation unit 13 applies the orthodontic force calculation model to beam element 51f of the simplified model 100 and calculates the orthodontic force generated in that portion based on the deformation rate of the corresponding portion of the aligner portion 50P. Similarly, the correction force calculation model is applied to the beam elements 51r, 52f, and 52r corresponding to the other parts of the aligner part 50P to calculate the correction force generated by each part.

[0073] Furthermore, the movement calculation unit 13 performs analysis processing by applying a damping model to each of the beam elements constituting the beam portions 36, 37, 46, and 47 corresponding to the surrounding tissue 60 of the simple model 100, and calculating the magnitude of the load generated by each beam element. For example, the movement calculation unit 13 applies a damping model to the beam elements 36x, 36y, and 36z corresponding to the surrounding tissue 60 on the crown side of the tooth 30, and calculates the magnitude of the load generated by the beam elements 36x, 36y, and 36z.

[0074] Then, the movement calculation unit 13 calculates the state of the simple model 100 after a predetermined time has elapsed based on the angles formed by each beam element, the length of each beam element, their rotational moments, and the characteristics set for each beam element (bending rigidity and torsional rigidity).

[0075] 6. Processing flow 7 to 11, the flow of processing by the simulation device 1 will be described. That is, the simulation method will be described using the simulation device 1. Hereinafter, the aligner used in orthodontic treatment will be referred to as aligner 80.

[0076] First, the information acquisition unit 11 acquires the patient's tooth information (S100) (tooth information acquisition step). The information acquisition unit 11 may acquire the tooth information from data output from an X-ray CT scanner or the like in accordance with standards such as DICOM. Alternatively, the information acquisition unit 11 may acquire the tooth information from information acquired by the computer main body 10 through direct communication with an X-ray CT scanner or the like. The three-dimensional information of the patient used to acquire the tooth information is not limited to information from the X-ray CT scanner, and may be information from a device other than the X-ray CT scanner that acquires three-dimensional information using light other than X-rays. The information acquisition unit 11 stores the acquired tooth information in the memory unit 2.

[0077] The information acquisition unit 11 acquires information about the patient, for example, by displaying an input screen on the display / output device 4 and prompting the user to input information. For example, the information acquired includes information about the patient's bone density and information about the patient's age, which are necessary for the analysis process. The information about the patient's bones may be calculated by the information acquisition unit 11 or another part of the computer main body 10 based on image information acquired from an X-ray CT device or the like. Alternatively, bone density information may be obtained based on the patient's age by referring to a table stored in the memory unit 2 in which standard bone densities are linked to ages. The information acquisition unit 11 stores the acquired information about the patient in the memory unit 2 as part of the tooth information.

[0078] The information acquisition unit 11 also acquires information about the material of the aligner used in orthodontic treatment by requesting the user to input the information. The information acquisition unit 11 stores the acquired information about the material of the aligner in the storage unit 2 as part of the aligner information.

[0079] Furthermore, the information acquiring unit 11 reads out the tooth information stored in the storage unit 2 and converts it into STL information (S110). The information acquiring unit 11 stores the converted STL information in the storage unit 2.

[0080] Next, a process for setting the ideal state of teeth alignment after orthodontic treatment is performed in accordance with the user's operation. Specifically, the display signal output unit 14 displays a three-dimensional image before orthodontic treatment on the display / output device 4 based on the STL information (S120) (see FIG. 8). FIG. 8 shows an STL image of teeth 71 to 76, which are the patient's maxillary teeth before orthodontic treatment. Note that FIG. 8 does not show the surrounding tissues surrounding the roots of each of the teeth 71 to 76.

[0081] While checking the three-dimensional image before orthodontic treatment displayed on the display / output device 4, the user operates the input device 3, such as a mouse, to set the position and posture of the teeth to be corrected. The arrangement calculation unit 12 creates information indicating the ideal state of tooth alignment set according to the user's operation (S130). The display signal output unit 14 creates a three-dimensional image indicating the ideal tooth alignment based on the created information and displays it on the display / output device 4 (see FIG. 9). FIG. 9 illustrates an example of a three-dimensional image of the ideal arrangement set by the user. Teeth 71i to 76i in FIG. 9 correspond to teeth 71 to 76 in FIG. 8, respectively. In FIG. 8, tooth 73 is the tooth to be corrected, and FIG. 9 illustrates an ideal arrangement state in which tooth 73 in FIG. 8 has been moved to the gap between tooth 72 and tooth 74.

[0082] The three-dimensional image of the ideal position set by the user may be displayed superimposed (overlaid) on the three-dimensional image before orthodontic treatment, or may be displayed in a different area from the three-dimensional image before orthodontic treatment.

[0083] When the user sets the ideal state of tooth alignment, the arrangement calculation unit 12 creates aligner information for the aligner 80 to be used in the orthodontic treatment of the patient.

[0084] Specifically, the array calculation unit 12 generates information about the dimensions of each part of the aligner 80, which is required to create a simple model, based on the tooth information. The array calculation unit 12 also generates aligner information that indicates the deformation rate (deformation amount) of the aligner 80 when orthodontic treatment is performed, based on information indicating the ideal tooth arrangement state set by the user and information indicating the tooth arrangement state before orthodontic treatment.

[0085] The array calculation unit 12 calculates the total magnitude of the orthodontic force applied to the teeth to be orthodontic treated by the aligner 80 used in the orthodontic treatment during the orthodontic treatment. Specifically, the array calculation unit 12 calculates the magnitude of the orthodontic force applied to the teeth during the orthodontic treatment by the aligner 80 used in the orthodontic treatment based on the orthodontic movement distance and information about the physical properties of the material of the aligner 80.

[0086] The array calculation unit 12 generates aligner information by linking information about the dimensions of the aligner 80 with information about the material (raw material) of the aligner 80. The array calculation unit 12 stores the aligner information and information about the calculated magnitude of the total orthodontic force in the storage unit 2.

[0087] Next, an analysis process is performed when the aligner is attached (movement calculation step). First, the aligner information is read (S150) (aligner information read / update step). Specifically, the array calculation unit 12 reads the aligner information of the aligner 80 by referring to the storage unit 2. The array calculation unit 12 also reads the STL information of the teeth before orthodontic treatment.

[0088] The array calculation unit 12 generates a simplified model 200 based on the read aligner information, tooth STL information, and tooth information (see FIG. 10). Specifically, the simplified model 200 is generated in which the patient's teeth 71-76, the tissues surrounding each of the teeth 71-76, and each portion of the aligner 80 are replaced with beam elements having corresponding lengths (S160) (simple model generation step). In FIG. 10, the tooth 71 is represented by a beam portion 71A in which beam element 71a and beam element 71b are linearly connected. Similarly, the teeth 72-76 are represented by beam portions 72A-76A. In FIG. 10, the beam portions 71A-76A are represented by thick, two-dot chain lines.

[0089] Of aligner 80 used in orthodontic treatment, the portion covering the section between teeth 71 and 72 is represented by beam section 81A, which is composed of four beam elements 811f, 811r, 812f, and 812r. Furthermore, the portion of aligner 80 covering the section between teeth 72 and 73 is represented by beam section 82A, which is also composed of four beam elements. Similarly, the portions of aligner 80 covering the sections between teeth 73 and 74, between teeth 74 and 75, and between teeth 75 and 76 are represented by beam sections 83A, 84A, and 85A. In FIG. 10, beam sections 83A, 84A, and 85A are represented by thick dashed lines.

[0090] The tissue surrounding tooth 71 is represented by beam portions 61a and 61b, each composed of three beam elements extending in the same direction as the X, Y, and Z axes. Similarly, the tissue surrounding teeth 72 to 76 are represented by beam portions 62a to 66b. In Fig. 10, beam portions 61a to 66b are indicated by thin solid lines.

[0091] Next, the movement calculation unit 13 applies the orthodontic force calculation model to each beam element constituting the beam portions 81A to 85A corresponding to the aligner 80 to calculate the orthodontic forces acting on the beam portions 81A to 85A (orthodontic force calculation step) (S170). The movement calculation unit 13 selects an orthodontic force calculation model corresponding to the material (material quality) of the aligner 80 input by the user, and calculates each orthodontic force. The movement calculation unit 13 associates the calculated orthodontic forces with the corresponding beam elements, respectively, and stores them in the memory unit 2 as orthodontic force data.

[0092] Based on the tooth information and the attenuation model, the movement calculation unit 13 sets characteristics corresponding to the surrounding tissues to each beam element corresponding to the tissues around the tooth (physical property parameter setting step) (S180). Taking the tissues around the tooth 71 as an example, the movement calculation unit 13 assigns the load characteristics of the surrounding tissues to each beam element constituting the beam portions 61a and 61b according to their directions based on the attenuation model. Similarly, for the tissues around the other teeth 72 to 76, the movement calculation unit 13 assigns corresponding characteristics to each beam element constituting the beam portions 62a to 66b based on the tooth information and the attenuation model. The movement calculation unit 13 selects an attenuation model according to patient information (such as bone density and age) input by the user and sets it to the beam elements corresponding to the surrounding tissues.

[0093] The movement calculation unit 13 sets bending stiffness and torsional stiffness according to the physical properties of the corresponding portion of the corresponding aligner 80 for each beam element constituting the beam portions 81A to 85A based on the aligner information.

[0094] The movement calculation unit 13 calculates the magnitude and direction of the forces and loads acting on each part of the simple model 200, and also calculates the changes over time of each (simulation step) (S190). Based on the calculation results, the movement calculation unit 13 changes information about the position and posture of each beam element after a certain period of time has elapsed. That is, the movement calculation unit 13 calculates the arrangement state of the beam portions 71A to 76A after a certain period of time has elapsed.

[0095] When a predetermined time has passed and it is determined that correction by aligner 80 has been completed, movement calculation unit 13 stores the information of simple model 200 at that time in memory unit 2. Display signal output unit 14 generates a three-dimensional image showing the arrangement of teeth 71-76 based on the information of simple model 200 analyzed by movement calculation unit 13, and displays it on display / output device 4 as a three-dimensional image showing the simulation results after correction (S200) (see FIG. 11).

[0096] FIG. 11 shows three-dimensional images of teeth 71s to 76s, which are the results of the simulation. Teeth 71s to 76s in FIG. 11 correspond to teeth 71 to 76 in FIG. 8, respectively. The three-dimensional image showing the simulation results may be superimposed on the three-dimensional image of the ideal teeth alignment so that the difference from the three-dimensional image of the ideal teeth alignment set by the user can be seen. Alternatively, it may be displayed in a different area from the three-dimensional image of the ideal teeth alignment. Alternatively, it may be superimposed on the three-dimensional image before orthodontic treatment so that the condition before orthodontic treatment can be compared. Alternatively, it may be displayed in a different area from the three-dimensional image before the ideal orthodontic treatment.

[0097] 7.Explanation of the effect In the simulation device 1 configured as described above, the movement calculation unit 13 performs processing to calculate the positional state of each tooth based on tooth information and aligner information. Therefore, analysis processing is performed based on the condition of the patient's teeth and surrounding tissues, and the characteristics of the aligners used in orthodontic treatment. In other words, the effects of orthodontic treatment can be predicted taking into account the patient's condition and the characteristics of the aligners. Furthermore, the movement calculation unit 13 calculates the magnitude of the load that the patient's teeth receive from the surrounding tissues during orthodontic treatment using a damping model. Because this damping model is a simple mathematical model, it does not require complex computational processing compared to conventional simulations. In other words, the simulation using the simulation device 1 of the present disclosure requires less computational power than conventional techniques. Therefore, accurate analysis processing that appropriately reflects the characteristics of the tissues surrounding the patient's teeth can be performed without the complex analytical processing required by conventional simulation devices. In other words, tooth movement during orthodontic treatment using aligners and the post-orthodontic tooth alignment can be accurately predicted without complex analytical processing. The dedicated program for the simulation device 1 and the simulation method using the simulation device 1 also have similar effects.

[0098] This damping model is a mathematical model based on the creep phenomenon of a specific material, which allows for accurate analysis that appropriately reflects the characteristics of surrounding tissues in actual orthodontic treatment, without the need for complex calculations.

[0099] Furthermore, in the simulation device 1 of the present disclosure, analysis processing is performed using a simplified model in which the teeth, the tissues surrounding the teeth, and the aligner are each represented by a plurality of beam elements, each of which has bending and torsional properties set according to the physical properties of the corresponding part.

[0100] This allows for the analysis of the forces acting on the teeth, surrounding tissues, and each part of the aligner, as well as their movements, during orthodontic treatment, through simple calculations.In other words, accurate analysis can be performed at a faster processing speed than conventional simulations, taking into account the morphological and physical characteristics of each part.

[0101] As shown in the above embodiment, for example, by representing a patient's teeth with two beam elements corresponding to the crown and root, respectively, the clinical characteristics of the teeth can be reflected in the simplified model. Furthermore, the aligner can be divided into regions where each aligner is placed, and the aligner can be represented using beam elements corresponding to each region. This allows for a simplified model that takes into account the size (area) of each region and the differences in forces acting on each region during orthodontic treatment.

[0102] In other words, by performing analysis using the simplified model constructed as described above, it is possible to perform an accurate simulation that takes into account the different characteristics of the teeth, the tissues surrounding the teeth, and each part of the aligner, as well as the size of each part and the differences in the forces acting on each part.

[0103] Furthermore, if a specific tooth has an attachment, the torsional stiffness of the beam element corresponding to the aligner associated with that tooth is set to a value greater than when no attachment is provided. In other words, the analysis is performed assuming that the part of the aligner associated with the tooth with the attachment has a greater torsional stiffness than normal. Therefore, no additional processing is required due to the presence of an attachment, and the analysis can be performed using the same process as in the normal case (when no attachment is provided).

[0104] The technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure. Furthermore, the present disclosure is not limited to the above-described embodiments as long as it conforms to the spirit of the disclosure described in the above-described embodiments. Therefore, the present disclosure may be a configuration in which at least two of the above-described embodiments are combined, or a configuration in which any of the components illustrated or described with reference numerals in the above-described embodiments is eliminated. [Explanation of symbols]

[0105] 1...simulation device 2...storage unit 3...input device 4...Display / output device 5...CPU 6...Memory 7...Interface section 10...Computer main body 11...Information acquisition unit 12...Array calculation unit 13...Movement calculation unit 14...Display signal output unit 20, 100, 200... Simple model 30, 40, 71-76... Teeth 50...Aligner 50P...Aligner part 60...Surrounding tissue 30A, 40A, 71A~76A, 81A~85A, 91~95...beam part

Claims

1. A simulation device for predicting the movement of a patient's teeth when orthodontic treatment is performed on the patient's teeth using aligners, comprising: a movement calculation unit that calculates an arrangement state indicating the arrangement position and posture of a predetermined tooth after orthodontic treatment based on tooth information including at least information on the shape of each of the patient's teeth, information indicating the arrangement state of the patient's teeth before the orthodontic treatment, information on the tissues surrounding the patient's teeth, and aligner information including at least information on the shape and physical properties of the aligner; the movement calculation unit calculates the positioning state based on the orthodontic force applied to the predetermined tooth by the aligner and the magnitude of the load generated by the tissue surrounding the predetermined tooth when the orthodontic force is applied to the predetermined tooth; the movement calculation unit calculates the magnitude of the load using an attenuation model in which the load attenuates over time in accordance with predetermined characteristics, thereby calculating the placement state; Simulation device.

2. the damping model is a mathematical model based on the creep phenomenon of a given material; The simulation device according to claim 1 .

3. The movement calculation unit performs the following based on the tooth information and the aligner information: The positioning state is calculated using a simplified model in which the aligner, the patient's teeth, and the tissues surrounding the teeth are each represented using a plurality of beam elements having a beam-like shape, each of the beam elements constituting the simplified model corresponds to a part of either the aligner, the tooth, or the tissue surrounding the tooth; the movement calculation unit calculates the arrangement state assuming that each of the beam elements has bending rigidity and torsional rigidity corresponding to physical properties of the corresponding part.

3. The simulation device according to claim 1.

4. The movement calculation unit When the tooth is provided with an attachment used for the orthodontic treatment, the torsional stiffness of the beam element corresponding to the portion of the aligner related to the tooth with the attachment is set to a value greater than when the tooth is not provided with the attachment, and the positioning state is calculated. The simulation device according to claim 3 .

5. A program for operating an electronic computing device as a simulation device for predicting the movement of a patient's teeth when orthodontic treatment of the patient's teeth is performed using aligners, the program comprising: The electronic computing device, a movement calculation unit that calculates an arrangement state indicating the arrangement position and posture of a predetermined tooth after orthodontic treatment based on tooth information including at least information on the shape of each of the patient's teeth, information indicating the arrangement state of the patient's teeth before the orthodontic treatment, information on the tissues surrounding the patient's teeth, and aligner information including at least information on the shape and physical properties of the aligner; the movement calculation unit calculates the positioning state based on the orthodontic force applied to the predetermined tooth by the aligner and the magnitude of the load generated by the tissue surrounding the predetermined tooth when the orthodontic force is applied to the predetermined tooth; the movement calculation unit calculates the magnitude of the load using an attenuation model in which the load attenuates over time in accordance with predetermined characteristics, thereby calculating the placement state; A program that operates as a simulation device.

6. 1. A simulation method for predicting tooth movement of a patient when orthodontic treatment of the patient's teeth using aligners is performed using an electronic computing device, comprising: a movement calculation step in which an electronic computing device calculates an arrangement state indicating the arrangement position and posture of a predetermined tooth after orthodontic treatment based on tooth information including at least information on the shape of each of the patient's teeth, information indicating the arrangement state of the patient's teeth before the orthodontic treatment, information on the tissues surrounding the patient's teeth, and aligner information including at least information on the shape and physical properties of the aligner; The movement calculation step is a step of calculating the positioning state based on the orthodontic force applied to the predetermined tooth by the aligner and the magnitude of the load generated by the tissue surrounding the predetermined tooth when the orthodontic force is applied to the predetermined tooth, In the movement calculation step, the magnitude of the load is calculated using a damping model that damps the load over time according to predetermined characteristics, and the placement state is calculated. Simulation method.

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