Dental appliance thickness estimation method, press film parameter estimation method, and storage medium

Abstract

The present application relates to the technical field of orthodontic digital design, and discloses a dental appliance thickness estimation method, a film pressing parameter estimation method and a storage medium, which comprises the following steps: a dental arch surface mesh model corresponding to a patient's dental arch is constructed, and a film surface mesh model corresponding to a to-be-pressed film patch is constructed and overlaid on the patient's dental arch; wherein the film surface mesh model has elastic properties between mesh nodes; given film pressing working condition information, the working condition information comprises film pressing pressure and film patch film pressing speed; according to the given elastic properties and the film pressing pressure, the stress of a target mesh node in the film surface mesh model is calculated; according to the film patch film pressing speed and the calculated stress of the target mesh node, the displacement of the target mesh node in the film surface mesh model is calculated; and according to the calculated displacement of the target mesh node, the appliance thickness of the target mesh node in the film surface mesh model after film pressing deformation is calculated.

Description

Technical Field

[0001] This invention relates to the field of orthodontic digital design technology, and in particular to a method for predicting the thickness of dental appliances, a method for predicting compression parameters, and a storage medium. Background Technology

[0002] Shell-shaped orthodontic appliances are a type of orthodontic device made of safe, elastic, transparent polymer material. They have the advantages of being completely invisible during the orthodontic process, aesthetically pleasing, easy to operate, and convenient for oral cleaning. Moreover, due to their transparent and aesthetically pleasing characteristics, the orthodontic process is completed almost imperceptibly to others, and they have gradually become the first choice for orthodontic patients.

[0003] In the manufacturing process, the most common technique is thermoforming, where a polymer sheet (film) is thermopressed onto a dental model representing the tooth layout and structure to form a negative mold. The excess material is then cut away to obtain a shell-shaped dental instrument. However, different patient jaw shapes exert varying degrees of stretching on the film, resulting in uneven appliance thickness and even film rupture.

[0004] Existing methods for addressing thickness inconsistencies, such as the molding method for shell-shaped orthodontic appliances disclosed in patent (application number CN202110218009.X), improve the thickness consistency of the finished appliance by adjusting the position of the dental model. However, while this is a solution, whether the thickness of the appliance obtained after position adjustment meets the requirements is generally estimated based on deformation, without considering the influence of process parameters during molding. Therefore, the actual thickness after molding still needs to be verified through simulation and other methods. Finite element simulation is commonly used in simulation methods, but building a finite element model that matches the vacuum hot molding environment is complex, costly, and slow. Furthermore, since shell-shaped orthodontic appliances are customized products, different finite element models need to be built for different patients when verifying the thickness of the shell-shaped appliance. This means that modeling, analyzing, and designing the appliance for each case is too slow and not conducive to widespread adoption.

[0005] Therefore, in view of the problems existing in the prior art, the present invention provides a technical solution to solve the technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method for predicting the thickness of dental orthodontic appliances, a method for predicting lamination parameters, and a storage medium. When predicting the thickness of the lamination after lamination, a simpler digital model can be used, which not only relates to the process parameters in lamination, but also makes the calculation simpler and faster. The thickness prediction results are accurate and reliable, and the evaluation speed is greatly improved.

[0007] To address the aforementioned technical problems, embodiments of the present invention provide a method for estimating the thickness of dental orthodontic appliances, used for vacuum thermoforming to manufacture dental orthodontic appliances. The method includes: constructing a dentinal surface mesh model corresponding to the patient's jaw and a membrane surface mesh model covering the patient's jaw corresponding to the membrane to be pressed; wherein, each node in the dentinal surface mesh model is a fixed node, and the mesh nodes in the membrane surface mesh model have elastic properties; providing pressing condition information, including pressing pressure and pressing speed; calculating the force on the target mesh node in the membrane surface mesh model based on the given elastic properties and the pressing pressure; calculating the displacement of the target mesh node in the membrane surface mesh model based on the pressing speed and the calculated force on the target mesh node; and calculating the appliance thickness at the location of the target mesh node after pressing deformation based on the calculated displacement of the target mesh node.

[0008] Compared to existing technologies, the embodiments of this invention construct surface mesh models of the patient's occlusal membrane, where the occlusal surface mesh has fixed nodes, and the nodes of the membrane surface mesh have elastic properties, respectively adapting to the actual state of the occlusal model and the membrane during the compression process. Then, the force on the membrane during compression, and the displacement of the mesh nodes after the membrane is subjected to force under elastic properties, can be calculated to determine the membrane's tension, thereby further determining the membrane's thickness. It is evident that using a mesh model combined with mechanical property calculations makes the estimation process consistent with the specific condition of the membrane after compression, thus not only speeding up the overall estimation but also obtaining a realistic and reliable thickness result that conforms to objective conditions. Because the model used is simple to build, the modeling cost is reduced, making the orthodontic appliance thickness estimation in this application more widely applicable.

[0009] Optionally, the elastic properties are characterized by the spring stiffness coefficient and the spring damping coefficient; the forces on the target mesh nodes in the diaphragm mesh model include: spring extension force, spring damping force, the mass gravity of the target mesh nodes in the diaphragm, and the pressure of the diaphragm. Since the diaphragm material has a certain elasticity, this application chooses to characterize the elastic properties between adjacent nodes in the diaphragm mesh using the characteristic parameters of the spring, simplifying the deformation of the diaphragm mesh between two adjacent nodes into spring deformation, making it easier to quantify the force and deformation calculation by using the spring characteristics as the estimated parameters.

[0010] Optionally, the step of calculating the displacement of the target grid node in the membrane surface grid model based on the membrane pressing speed and the calculated force on the target grid node includes: constructing a mechanical calculation model of the displacement and deformation rate of the target grid node after being subjected to force; and calculating the displacement of the target grid node after being subjected to force based on the mechanical calculation model according to the calculated force on the target grid node.

[0011] Optionally, the mechanical calculation model for the displacement and deformation velocity of the spring mass includes: constructing a first relationship between the force, displacement, and velocity of the target mesh node using Taylor expansion; constructing a second relationship between the displacement and velocity of the target mesh node based on the implicit Euler method; constructing a third relationship based on Newton's second law, which is the differential of the acceleration and velocity of the target mesh node after being subjected to force with respect to unit time; and solving the first relationship based on the second and third relationships to obtain the relationship between the resultant force and displacement of the target mesh node after being subjected to force.

[0012] Optionally, the step of calculating the displacement of the target mesh node after being subjected to force based on the calculated force and the mechanical calculation model includes: iteratively calculating the displacement of the target mesh node after being subjected to force based on the mechanical calculation model according to the change per unit time. Since elastic deformation does not change linearly with respect to time, further iterative calculation based on the change per unit time makes the calculated displacement more consistent with the actual change process.

[0013] Optionally, the step of iteratively calculating the displacement of the target mesh node under stress in the mechanical calculation model based on unit time variation includes: after each iteration, performing a collision check on the target mesh node and each node in the dental and maxillofacial mesh model; if a collision is detected, the collision is resolved. Since the dental and maxillofacial model and the diaphragm model may intersect during the calculation process, while in reality the positions of the diaphragm and the dental and maxillofacial structures do not overlap, performing a node collision check after each iteration and resolving the collision after detection makes the calculated displacement more consistent with reality and the prediction results more reliable and accurate.

[0014] Optionally, the collision check between the target mesh node and each node in the dental and maxillofacial mesh model includes: generating a ray from the target mesh node position before the iterative calculation to the new position after the iterative calculation; calculating the intersection of the ray with each facet in the dental and maxillofacial mesh model; and if a collision is detected, resolving the collision includes: if the ray intersects with any facet in the dental and maxillofacial mesh model, it is determined that a collision has been detected; when resolving the collision, updating the new position of the target mesh node after the iterative calculation to the intersection point.

[0015] Optionally, the spring stiffness coefficient and spring damping coefficient are determined based on the stiffness of the material used in the diaphragm to be estimated; and / or, the pressing pressure is determined based on the pressure value of the pressing machine and the vacuum pressure used in the vacuum hot pressing process to be estimated.

[0016] Optionally, the step of calculating the orthodontic thickness at the location of the target mesh node in the membrane mesh model after compression deformation based on the calculated displacement of the target mesh node includes: presetting an initial thickness h0 for each membrane panel in the membrane mesh model to form a membrane mesh unit; calculating the volume of the membrane mesh unit to be equal to h0*A0, where A0 is the initial area of ​​the membrane panel; calculating the mesh area Ai of the membrane panel where each target mesh node is located after deformation based on the displacement of all target mesh nodes in the membrane mesh model; and, based on the principle of constant membrane volume, calculating the thickness hi = h0*A0 / Ai of the membrane mesh unit where each membrane panel is located after deformation based on the initial thickness h0, the mesh areas A0 and Ai of the membrane panel where the target mesh node is located before and after compression deformation. Since the volume of the membrane is almost constant during deformation, the height of the triangular mesh is further limited. Based on the principle of constant volume, the corresponding change in height is calculated after the area changes, making the height calculation faster and simpler.

[0017] The embodiments of the present invention also provide a method for verifying compression membrane parameters, comprising: acquiring compression membrane operating condition information and membrane specifications; calculating the orthodontic appliance thickness at the location of the target mesh node of the membrane surface mesh model after compression deformation according to the above-mentioned dental appliance thickness estimation method; determining whether the orthodontic appliance thickness at the location of each target mesh node is greater than a first preset value, and whether the difference between the orthodontic appliance thicknesses at the locations of each target mesh node is less than a second preset value; determining that the verification has failed when the orthodontic appliance thickness at the location of each target mesh node is less than or equal to the first preset value, or the difference between the orthodontic appliance thicknesses at the locations of each target mesh node is greater than or equal to the second preset value, and providing feedback to adjust the compression membrane operating condition information and / or the membrane specifications.

[0018] In this embodiment, the thickness of the orthodontic appliance obtained after compression molding at the target position is estimated, and the compression molding parameters are further verified. The thicknesses at each position are compared, and the relationship between the thickness differences at different positions and the preset values ​​is compared. This verifies whether the thickness of the orthodontic appliance meets the requirements. If it does not meet the requirements, the parameter adjustment information is fed back. This allows for the verification of more suitable compression molding parameters through pre-simulated thickness, reducing simulation verification or physical verification, lowering costs, and accelerating the verification feedback speed.

[0019] Optionally, whether the difference in orthodontic thickness between the locations of each target grid node is less than a second preset value specifically refers to whether the difference in orthodontic thickness between the locations of each target grid node within a predetermined detection window is less than a second preset value. Further, the difference in orthodontic thickness between the locations of each target grid node within the predetermined area must be small to avoid sudden changes in thickness causing localized stress concentration in the orthodontic, and to prevent breakage of the orthodontic during removal or wearing.

[0020] Embodiments of the present invention also provide a computer-readable storage medium storing a computer program, characterized in that, when the computer program is executed by a processor, it implements the dental appliance thickness estimation method as described above; or, implements the pressure film parameter verification method as described above. Attached Figure Description

[0021] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0022] Figure 1 This is a flowchart of the method for estimating the thickness of dental appliances provided in the first embodiment of this application;

[0023] Figure 2 This is a schematic diagram of the diaphragm in the initial pressing state during the dental appliance thickness estimation method provided in the first embodiment of this application;

[0024] Figures 3-5 These are schematic diagrams showing the state of the diaphragm during the pressing process in the dental appliance thickness estimation method provided in the first embodiment of this application.

[0025] Figure 6 This is a schematic diagram of the diaphragm in the completed pressing state in the dental appliance thickness estimation method provided in the first embodiment of this application;

[0026] Figure 7 This is a flowchart of the collision test in the dental appliance thickness estimation method provided in the second embodiment of this application;

[0027] Figure 8 This is a flowchart of the pressure film parameter verification method provided in the third embodiment of this application;

[0028] Figure 9 This is a schematic diagram of the electronic device provided in the fourth embodiment of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the various embodiments of this invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this invention to facilitate a better understanding of this application. However, the technical solutions claimed in the claims of this application can be implemented even without these technical details and with various variations and modifications based on the following embodiments.

[0030] In embodiments of the present invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings. These terms are primarily for the purpose of better describing the present invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationships; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the present invention according to the specific circumstances.

[0031] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0032] The following details the implementation of the dental appliance thickness estimation method of this application. The following implementation details are provided for ease of understanding and are not necessary for implementing this solution.

[0033] First, it should be noted that the dental appliance thickness estimation method in this embodiment can be implemented through hardware or a combination of computer software and hardware. For hardware implementation, the dental appliance thickness estimation method can be implemented using one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, other electronic devices for implementing accessory design functions, or a selection and combination of the above devices.

[0034] The first embodiment of the present invention provides a method for estimating the thickness of dental orthodontic appliances, used for vacuum thermoforming of dental orthodontic appliances. The thickness estimation process can be as follows: Figure 1 As shown, it specifically includes:

[0035] Step 101: Construct the dentition surface mesh model corresponding to the patient's dentition and the membrane surface mesh model covering the diaphragm to be compressed on the patient's dentition.

[0036] Specifically, in the dental surface mesh model, each node is a fixed node, while in the membrane surface mesh model, the mesh nodes have elastic properties. It can be understood that, since the dental model is a printed solid in the hot-pressing process and will not deform during the process, a surface mesh model with fixed nodes is used. The membrane, however, is subjected to pressure adsorption during hot pressing, deforming and stretching to form a negative mold attached to the outside of the dental model. Since the membrane material is generally a high-molecular polymer, which has a certain degree of elasticity, a surface mesh model with elastic mesh nodes is used, allowing the membrane model to undergo elastic deformation.

[0037] In some embodiments, the geometry of the patient's dental model can be obtained by scanning with an intraoral scanner. A base structure can be added to the bottom of the dental model to make it easier to place the printed object more flat. Wax filling can also be added to the dental model at the required locations to reduce undercuts and facilitate the removal of the orthodontic appliance later.

[0038] In some embodiments, the elastic properties of the diaphragm mesh can be characterized by the properties of a spring, specifically by the spring stiffness coefficient and the spring damping coefficient. Regarding the geometry, the diaphragm mesh can have a given initial thickness, and its shape can be a square diaphragm, a circular diaphragm, or other shapes, which will not be listed here.

[0039] Step 102: Provide the molding condition information.

[0040] Specifically, the operating condition information includes: membrane pressing pressure and diaphragm pressing speed. In some embodiments, the membrane pressing pressure may be related to the vacuum pressure; for example, if a negative pressure membrane pressing device is used, the membrane pressing pressure can be equal to the negative of the vacuum pressure. Alternatively, it may be related to the membrane pressing equipment. In some embodiments, the diaphragm pressing speed is related to the membrane pressing equipment, and the relevant parameters of the membrane pressing equipment can be adjusted as needed according to the specifications of the membrane pressing equipment.

[0041] In some embodiments, the spring stiffness coefficient and spring damping coefficient can be determined based on the stiffness of the material used in the diaphragm to be estimated. In practical applications, the thickness of the material used in the diaphragm can be determined empirically or experimentally, which will not be elaborated further here.

[0042] Step 103: Calculate the force on the target mesh node in the membrane mesh model based on the given elastic properties and the membrane pressure.

[0043] Specifically, the forces acting on the target mesh nodes in the diaphragm mesh model include: spring extension force, spring damping force, the gravity of the target mesh nodes in the diaphragm, and the pressure exerted by the diaphragm. Since the diaphragm material has a certain degree of elasticity, this application chooses to characterize the elastic properties between adjacent nodes in the diaphragm mesh using spring characteristic parameters (such as spring stiffness coefficient and spring damping coefficient). This simplifies the deformation of the diaphragm mesh between two adjacent nodes to spring deformation, making it easier to quantify the force and deformation calculations by using spring characteristics as the predicted parameters.

[0044] In some embodiments, when calculating the forces acting on a node, the internal and external forces can be analyzed separately. Internal forces are determined by the properties of the material itself. For example, if the diaphragm is characterized using a spring-mass system, the forces acting inside the spring can be considered as spring extension force and spring damping force, which can be expressed by the following formulas:

[0045] Spring extension force: F s =-k s (|X ij |-r)X ij ;

[0046] Spring damping force: F d =-k d ·X(V ij ·X ij );

[0047] In the formula, k s X is the spring stiffness coefficient, r represents the rest length of the spring, and X is the spring stiffness coefficient. ij V represents the displacement difference between two nodes of the spring (i.e., two adjacent nodes in the diaphragm mesh). ij k represents the velocity difference between the two nodes of the spring. d X represents the spring damping coefficient, and X represents the die pressing speed.

[0048] Furthermore, the external forces acting on the diaphragm include gravity and vacuum negative pressure, which can be expressed as follows:

[0049] Gravity of a particle: Fg = -mg;

[0050] Pressure on membrane = vacuum negative pressure: F vac =-pAn;

[0051] Where p is the vacuum pressure value, and An represents the area of ​​the grid where the target grid node is located.

[0052] Therefore, the net force on the diaphragm is f = F. s +F d +Fg+F vac .

[0053] Step 104: Calculate the displacement of the target mesh node in the membrane surface mesh model based on the membrane pressing speed and the calculated force on the target mesh node.

[0054] In some embodiments, the specific steps include constructing a mechanical calculation model of the displacement and deformation velocity of the target mesh node after being subjected to force, and calculating the displacement of the target mesh node after being subjected to force based on the calculated force on the target mesh node and the mechanical calculation model. In some embodiments, the constructed mechanical calculation model of the displacement and deformation velocity relationship may further include:

[0055] The first relationship between the force, displacement, and velocity of the target mesh node is constructed using Taylor expansion.

[0056] The first relation includes:

[0057] f(x0+dx,v0+dv)=f0+df / dx*dx+df / dv*dv;

[0058] f0 = f(x0, v0));

[0059] Where x0 is the initial position of the target grid node and v0 is the initial velocity of the target grid node.

[0060] Based on the implicit Euler method, a second relationship between the displacement and velocity of the target mesh nodes is constructed; the second relationship is as follows:

[0061] dx = (v + dv) * dt;

[0062] Based on Newton's second law, a third relationship is constructed that represents the differential of the acceleration and velocity of the target mesh node after being subjected to force with respect to a unit of time; the third relationship is as follows:

[0063] dv=M^-1*f(x0+dx,v0+dv)*dt;

[0064] Where M is a matrix composed of the mass of each grid cell in the membrane surface grid.

[0065] Based on the second and third relational expressions, the first relational expression is solved to obtain the relationship between the resultant force and displacement of the target mesh node after it is subjected to force.

[0066] Specifically, substituting the second and third relations above into the Taylor expansion and solving for them yields:

[0067]

[0068] Where M is the matrix composed of the masses of each grid cell in the membrane surface grid, v tx represents the derivative of velocity v with respect to time t. i v represents the displacement of the i-th grid node. i This represents the velocity of the i-th grid node.

[0069] Next, based on the calculated forces acting on the target mesh nodes, the displacement of the target mesh nodes after being subjected to force is calculated using the mechanical calculation model. In some embodiments, this step further includes: iteratively calculating the displacement of the target mesh nodes after being subjected to force based on the mechanical calculation model according to the change per unit time. Since elastic deformation does not change linearly with respect to time, further iterative calculation based on the change per unit time makes the calculated displacement more consistent with the actual change process.

[0070] It can be understood that the form of a linear equation system can be obtained. By using some numerical solution methods for linear equation systems, such as the conjugate gradient method, the velocity variable dv to be solved can be obtained. Substituting the obtained dv into the relationship between velocity and displacement, the target mesh node position dx after each iteration can be obtained.

[0071] Step 105: Based on the calculated displacement of the target mesh node, calculate the orthodontic thickness at the location of the target mesh node after the membrane deformation.

[0072] Specifically, this step can be achieved by setting an initial thickness h0 for each membrane surface in the membrane mesh model as described in step 101, thus forming membrane mesh units. Specifically, when the membrane is of uniform thickness, the initial thickness of all membrane surfaces is h0. When the membrane is of non-uniform thickness, a base thickness can be given first, and then an expression can be formed based on the relationship between the thickness at each target location and the initial thickness.

[0073] The volume of the membrane mesh element is calculated to be h0*A0, where A0 is the initial area of ​​the membrane surface. Based on the displacement of all target mesh nodes in the membrane surface mesh model, the mesh area A of the membrane surface where each target mesh node is located after deformation is calculated. i Based on the principle of constant diaphragm volume, and according to the initial thickness h0, the grid area A0 and A of the diaphragm surface where the target grid node is located before and after the compression deformation. i The thickness of each diaphragm sheet after deformation is calculated as hi = h0 * A0 / A. i Since the volume of the diaphragm remains almost constant during deformation, the height of the triangular mesh is further limited. Based on the principle of constant volume, the height is calculated according to the change in area, making the height calculation faster and simpler.

[0074] In some embodiments, the grid area A iThe calculation process can be as follows:

[0075] Assume triangular facet F i (i = 1..N, where N represents the number of triangular facet elements) The three nodes are P i0 ,P i1 and P i2 Their coordinates are: P i0 =(x i0 ,y i0 ,z i0 ), P i1 =(x i1 ,y i1 ,z i1 ), P i2 =(x i2 ,y i2 ,z i2 ).

[0076] From P i0 Starting from this point, construct two edge vectors:

[0077] u i 10 =P i1 -P i0 =(x i1 -x i0 ,y i1 -y i0 ,z i1 -z i0 ),

[0078] v i 20 =P i1 -P i0 =(x i2 -x i0 ,y i2 -y i0 ,z i2 -z i0 ).

[0079] The cross product u of two edge vectors i 10 ×v i 20 The modulus is equal to u i 10 and v i 20 Let be the area of ​​the parallelogram with adjacent sides, therefore the area of ​​the triangular facet is half the area of ​​the parallelogram. The cross product formula can be written as:

[0080]

[0081] The magnitude of the cross product vector is:

[0082]

[0083] Let the edge vector u i 10 and v i 20 Substituting the coordinates, the formula for the area of ​​the triangular facet can be written as:

[0084] A i =1 / 2{[(y i1 -y i0 (z) i2 -z i0 )-(z i1 -z i0 )(y i2 -y i0 )] 2 +[(z i1 -z i0 (x) i2 -x i0 )-(x i1 -x i0 (z) i2 -z i0 )] 2 +[(x i1 -x i0 )(y i2 -y i0 )-(y i1 -y i0 (x) i2 -x i0 )] 2} 1 / 2

[0085] It is worth mentioning that in this implementation, the value of h0 does not need to be given, and the calculated result is h. i The proportional relationship between h0 and the diaphragm can be used to calculate the change between the thickness of the orthodontic appliance obtained by compression and the initial thickness of the diaphragm, or the value of h0 can be given to evaluate the estimated thickness of the orthodontic appliance after compression with a selected diaphragm specification.

[0086] It should be noted that, based on the above estimation process, the following diagram illustrates the changes in the diaphragm during the pressing process. Figures 2-6 The numbers represent the initial moment of the molding process, the molding process itself, and the final molding effect, respectively.

[0087] As can be seen, compared with the prior art, this embodiment constructs a surface mesh model of the patient's occlusal membrane, where the occlusal surface mesh has fixed nodes, and the nodes of the membrane surface mesh have elastic properties, respectively adapting to the actual state of the occlusal model and the membrane during the compression process. Then, the force on the membrane during compression and the displacement of the mesh nodes after the membrane is subjected to force under elastic properties are calculated to determine the membrane's tension, thereby further determining the membrane's thickness. It is evident that using a mesh model combined with mechanical property calculations makes the estimation process consistent with the specific situation of the membrane after compression, thus not only speeding up the overall estimation but also obtaining a realistic and reliable thickness result that conforms to objective conditions. Because the model used is simple to build, the modeling cost is reduced, making it easier to extend the orthodontic appliance thickness estimation in this application to more application scenarios. This embodiment further uses the characteristic parameters of a spring to characterize the elastic properties between adjacent nodes in the membrane mesh, simplifying the deformation of the membrane mesh between two adjacent nodes into spring deformation, making it easier to quantify the force and deformation calculations using spring characteristics as estimation parameters.

[0088] The second embodiment of this application provides a method for estimating the thickness of a dental appliance. Compared with the previous embodiment, the main improvement of this embodiment is that a collision inspection step after diaphragm deformation is added. After a collision is detected, the collision is removed, so that the calculated displacement is more in line with reality and the prediction result is more reliable and accurate.

[0089] Specifically, the process of iteratively calculating the displacement of the target mesh node under stress based on the mechanical calculation model, according to the change per unit time, further includes a collision check step, such as... Figure 7 As shown, the details are as follows:

[0090] Step 701: After each iteration of calculation, a collision check is performed between the target mesh node and each node in the dental and maxillofacial mesh model.

[0091] In some embodiments, the collision detection step may include: generating a ray from the target mesh node position before the iterative calculation to the new position after the iterative calculation; calculating the intersection of the ray with each facet in the dental and maxillofacial mesh model; if the ray intersects with any facet in the dental and maxillofacial mesh model, then a collision is detected.

[0092] Step 702: If a collision is detected, then the collision is resolved.

[0093] Specifically, when collision resolution is required, the new position of the target mesh node, calculated iteratively, is updated to the intersection point. In other words, the intersection point is used as the new position of the target mesh node.

[0094] As can be seen, in this embodiment, the dental model and the diaphragm model may intersect during the calculation process, while in reality the positions of the diaphragm and the dental model do not overlap. Therefore, a collision check is performed on the nodes after each iteration of the calculation, and the collision is resolved after a collision is detected, so that the calculated displacement is more consistent with reality and the prediction result is more reliable and accurate.

[0095] The third embodiment of this application provides a method for verifying pressure film parameters. The verification method in this embodiment is as follows: Figure 8 As shown, it specifically includes:

[0096] Step 801: Obtain membrane pressing condition information and membrane specifications.

[0097] Specifically, the diaphragm pressing condition information may include pressing pressure and diaphragm pressing speed, and the diaphragm specifications may include diaphragm material and orthodontic appliance thickness.

[0098] Step 802: Calculate the thickness of the orthodontic appliance at the location of the target mesh node after the membrane deformation using the above-mentioned method for estimating the thickness of the dental appliance.

[0099] Specifically, this step can be calculated using the dental appliance thickness estimation method in the first or second implementation method, and the specific process will not be described in detail.

[0100] Step 803: Determine whether the thickness of the orthodontic appliance at the location of each target grid node is greater than the first preset value, and whether the difference between the thicknesses of the orthodontic appliances at the locations of each target grid node is less than the second preset value.

[0101] Step 804: If the thickness of the orthodontic appliance at the location of each target grid node is less than or equal to the first preset value, or if the difference between the thicknesses of the orthodontic appliances at the locations of each target grid node is greater than or equal to the second preset value, the verification is determined to be a failure.

[0102] Specifically, during verification, it is necessary not only to determine the thickness of the diaphragm itself at each location, but also to assess the difference in thickness of the orthodontic appliance at different locations. Due to significant differences in appliance thickness, stress concentration may occur at relatively thinner locations, increasing the likelihood of breakage and hindering appliance wear. In some embodiments, based on the calculated thickness of the orthodontic appliance at each target grid node location, a thickness distribution map of the orthodontic appliance can be drawn. The maximum and minimum thickness values ​​on the orthodontic appliance are extracted, and the difference between the maximum and minimum thicknesses is compared. This difference value can then be compared with a second preset value. In some embodiments, the second preset value can be set to 0.2 mm, meaning that if the thickness range at each location among all target grid nodes on the orthodontic appliance is greater than 0.2 mm, the verification is considered a failure.

[0103] In some embodiments, the difference in orthodontic appliance thickness at the locations of each target grid node can be limited to the difference in orthodontic appliance thickness at the locations of each target grid node within a predetermined detection window. In other words, the difference in orthodontic appliance thickness between each target grid node needs to be small within a certain distance. It should be noted that the detection window can be preset to the size of a single tooth, the size of two teeth, or other sizes as needed; these will not be listed here.

[0104] Step 805: Feedback and adjustment of the membrane pressing condition information and / or the membrane specifications.

[0105] Specifically, the material and thickness of the diaphragm can be adjusted, or the lamination equipment can be modified. The specific adjustment method can be chosen based on experience. For example, if the overall thickness of the orthodontic appliance is too small, a thicker diaphragm can be selected to ensure that the manufactured appliance is not too thin and easily damaged.

[0106] As can be seen, this embodiment further verifies the pressing parameters by estimating the thickness of the orthodontic appliance at the target location after pressing. It compares the thickness at each location and the relationship between the thickness differences at different locations and preset values ​​to verify whether the thickness of the obtained orthodontic appliance meets the requirements. If it does not meet the requirements, feedback is provided to adjust the parameters. This allows for the verification of more suitable pressing parameters through pre-simulated thickness, reducing simulation or physical verification, lowering costs, and accelerating verification feedback. Furthermore, it limits the thickness difference of the orthodontic appliance at each target grid node location within a predetermined area to a small extent, avoiding sudden thickness changes that could cause localized stress concentration in the orthodontic appliance and prevent breakage during removal or wearing.

[0107] The fourth embodiment of this application relates to an electronic device, such as... Figure 9 As shown, it includes: at least one processor 1101; and a memory 1102 communicatively connected to the at least one processor 1101; wherein the memory 1102 stores instructions executable by the at least one processor 1101, the instructions being executed by the at least one processor 1101 to enable the at least one processor 1101 to perform the dental appliance thickness estimation method in the first or second embodiment described above, or to implement the pressure film parameter verification method in the third embodiment described above.

[0108] The memory and processor are connected via a bus, which can include any number of interconnecting buses and bridges, connecting various circuits of one or more processors and memories. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0109] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0110] Another embodiment of this application relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the method embodiments described above.

[0111] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0112] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. A method for estimating the thickness of a dental appliance, characterized in that, A method for estimating the thickness of dental orthodontic appliances used in vacuum thermoforming includes: A dentistry surface mesh model corresponding to the patient's dentition and a membrane surface mesh model corresponding to the membrane to be compressed are constructed respectively; wherein, each node in the dentistry surface mesh model is a fixed node, and the mesh nodes in the membrane surface mesh model have elastic properties; Given membrane pressing condition information, the condition information includes: membrane pressing pressure and membrane pressing speed; Based on the given elastic properties and the pressure applied to the membrane, calculate the force on the target mesh node in the membrane mesh model; Based on the membrane pressing speed and the calculated force on the target mesh node, the displacement of the target mesh node in the membrane surface mesh model is calculated. Based on the calculated displacement of the target mesh node, the thickness of the orthodontic device at the location of the target mesh node after the membrane deformation is calculated.

2. The method for estimating the thickness of dental appliances according to claim 1, characterized in that, The elastic properties are characterized by the spring stiffness coefficient and the spring damping coefficient. The forces acting on the target mesh nodes in the diaphragm mesh model include: spring extension force, spring damping force, the mass gravity of the target mesh nodes in the diaphragm, and the membrane pressure.

3. The method for estimating the thickness of dental appliances according to claim 2, characterized in that, The step of calculating the displacement of the target mesh nodes in the membrane surface mesh model based on the membrane pressing speed and the calculated force on the target mesh nodes includes: Construct a mechanical calculation model of the displacement and deformation rate of the target mesh node after being subjected to force; Based on the calculated forces acting on the target mesh nodes, the displacement of the target mesh nodes after being subjected to forces is calculated using the mechanical calculation model.

4. The method for estimating the thickness of dental appliances according to claim 3, characterized in that, The mechanical calculation model for the displacement and deformation velocity of the spring mass includes: The first relationship between the force, displacement, and velocity of the target mesh node is constructed using Taylor expansion. Based on the implicit Euler method, a second relationship between the displacement and velocity of the target mesh nodes is constructed; Based on Newton's second law, a third relationship is constructed that relates the acceleration and the velocity of the target mesh node after being subjected to force to the differential of the velocity per unit time. Based on the second and third relational expressions, the first relational expression is solved to obtain the relationship between the resultant force and displacement of the target mesh node after it is subjected to force.

5. The method for estimating the thickness of dental appliances according to claim 3, characterized in that, The step of calculating the displacement of the target mesh node after being subjected to force based on the calculated force on the target mesh node and the mechanical calculation model includes: Based on the change per unit time, the displacement of the target mesh node after being subjected to force is iteratively calculated using the mechanical calculation model.

6. The method for estimating the thickness of dental appliances according to claim 5, characterized in that, The step of iteratively calculating the displacement of the target mesh node after being subjected to force based on the mechanical calculation model according to the change per unit time includes: After each iteration of calculation, a collision check is performed between the target mesh node and each node in the dental and maxillofacial mesh model; If a collision is detected, the collision is resolved.

7. The method for estimating the thickness of dental appliances according to claim 6, characterized in that, The collision check between the target mesh node and each node in the dental and maxillofacial mesh model includes: A ray is generated from the target mesh node position before the iterative calculation to the new position after the iterative calculation. Calculate the intersection of the ray with each facet in the dental and maxillofacial mesh model; The step of resolving the collision if a collision is detected includes: If the ray intersects with any facet in the dental mesh model, it is determined that a collision has been detected. When resolving a collision, the new position of the target mesh node, calculated iteratively, is updated as the intersection point.

8. The method for estimating the thickness of dental appliances according to claim 2, characterized in that, The spring stiffness coefficient and spring damping coefficient are determined based on the stiffness of the material used in the diaphragm to be estimated; and / or, the pressing pressure is determined based on the pressure value of the pressing machine and the vacuum pressure used in the vacuum hot pressing process to be estimated.

9. The method for estimating the thickness of dental appliances according to any one of claims 1-8, characterized in that, The step of calculating the orthodontic thickness at the location of the target mesh node after compression deformation, based on the calculated displacement of the target mesh node, includes: An initial thickness h0 is preset for each membrane surface in the membrane surface mesh model to form a membrane mesh unit; The volume of the membrane mesh element is calculated to be equal to h0*A0, where A0 is the initial area of ​​the membrane surface; Based on the displacement of all target mesh nodes in the membrane surface mesh model, calculate the mesh area Ai of each target mesh node in the membrane surface after deformation; Based on the principle of constant diaphragm volume, the thickness hi of each diaphragm grid cell after deformation is calculated according to the initial thickness h0, the grid area A0 and Ai of the diaphragm surface where the target grid node is located before and after the compression deformation, which is the initial thickness h0, and the grid area A0 and Ai of the diaphragm surface where the target grid node is located.

10. A method for verifying compression molding parameters, characterized in that, include: Obtain information on membrane pressing conditions and membrane specifications; The method for estimating the thickness of a dental appliance according to any one of claims 1-9 calculates the thickness of the appliance at the location of the target mesh node after compression deformation using a membrane mesh model. Determine whether the thickness of the orthodontic appliance at each target grid node location is greater than a first preset value, and whether the difference between the thicknesses of the orthodontic appliances at each target grid node location is less than a second preset value; if the thickness of the orthodontic appliance at each target grid node location is less than or equal to the first preset value, or the difference between the thicknesses of the orthodontic appliances at each target grid node location is greater than or equal to the second preset value, it is determined as a verification failure, and feedback is given to adjust the pressure membrane condition information and / or the diaphragm specifications.

11. The method for verifying pressure film parameters according to claim 10, characterized in that, Whether the difference in the thickness of the orthodontic appliance at the location of each target grid node is less than the second preset value is specifically: whether the difference in the thickness of the orthodontic appliance at the location of each target grid node within the predetermined detection window is less than the second preset value.

12. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the method for estimating the thickness of a dental appliance as described in any one of claims 1 to 9; or, it implements the method for verifying the pressure film parameters as described in claim 10 or 11.

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