Shell dental instrument manufacturing method

Abstract

An aspect of the present application provides a method of shell dental appliance fabrication, comprising: obtaining a three-dimensional digital model of a tooth; generating a non-parametric three-dimensional digital model of a shell dental appliance based on the three-dimensional digital model of the tooth; generating a parametric three-dimensional digital model of the shell dental appliance based on the non-parametric three-dimensional digital model of the shell dental appliance; modifying at least one geometric parameter of the parametric three-dimensional digital model of the shell dental appliance; generating a 3D printing digital file based on the modified parametric three-dimensional digital model of the shell dental appliance; and controlling a 3D printing device to fabricate the shell dental appliance using the 3D printing digital file.

Description

Technical Field

[0001] This application generally relates to methods for manufacturing shell-shaped dental instruments, and in particular to methods for manufacturing shell-shaped dental instruments based on 3D printing technology. Background Technology

[0002] Due to their aesthetic appeal, convenience, and ease of cleaning, shell-shaped dental instruments based on polymer materials (such as shell-shaped appliances and shell-shaped retainers) are becoming increasingly popular.

[0003] The traditional method for manufacturing shell-shaped dental instruments is based on thermoforming. However, the inherent limitations of this process restrict various aspects of shell-shaped dental instruments.

[0004] In view of the above, it is necessary to develop a new method for manufacturing shell-shaped dental instruments in order to get rid of the limitations of traditional processes on shell-shaped dental instruments in all aspects. Summary of the Invention

[0005] One aspect of this application provides a method for manufacturing a shell-shaped dental instrument, comprising: acquiring a three-dimensional digital model of a tooth; generating a non-parametric three-dimensional digital model of the shell-shaped dental instrument based on the three-dimensional digital model of the tooth; generating a parametric three-dimensional digital model of the shell-shaped dental instrument based on the non-parametric three-dimensional digital model of the shell-shaped dental instrument; modifying at least one geometric parameter of the parametric three-dimensional digital model of the shell-shaped dental instrument; generating a 3D printing digital file based on the modified parametric three-dimensional digital model of the shell-shaped dental instrument; and controlling a 3D printing device to manufacture the shell-shaped dental instrument using the 3D printing digital file.

[0006] In some embodiments, the shell-shaped dental instrument may be a shell-shaped orthodontic appliance used to reposition teeth from a first layout to a second layout.

[0007] In some implementations, a non-parametric 3D digital model expresses its geometric shape using only geometric data; a parametric 3D digital model expresses its geometric shape using both geometric data and parametric description.

[0008] In some implementations, the geometric parameters include thickness.

[0009] In some implementations, the parameterized three-dimensional digital model may be a parameterized shell element model.

[0010] In some embodiments, the method for manufacturing a shell-shaped dental instrument may further include: verifying a parametric three-dimensional digital model of the shell-shaped dental instrument, wherein modifications to the parametric three-dimensional digital model of the shell-shaped dental instrument are made based on the results of the verification.

[0011] In some implementations, the verification may be based on finite element analysis.

[0012] In some implementations, the non-parametric 3D digital model may be an STL model. Attached Figure Description

[0013] The above and other features of this application will become more fully clear through the following description and appended claims, in conjunction with the accompanying drawings. It should be understood that these drawings depict only a few embodiments of this application and should not be considered as limiting the scope of the application. The application will be described more clearly and in more detail through the use of the drawings.

[0014] Figure 1 This is a schematic flowchart illustrating a method for manufacturing a shell-shaped dental instrument according to one embodiment of this application;

[0015] Figure 1A This is a schematic flowchart illustrating the generation of a parametric 3D digital model of a shell-shaped dental instrument based on a 3D digital model of teeth, as described in one embodiment of this application.

[0016] Figure 2 A simplified numerical model of one embodiment of this application is illustrated schematically;

[0017] Figure 3 This illustration schematically demonstrates the relationship between the force value and cross-sectional area of ​​a shell-shaped orthodontic appliance in one embodiment of this application;

[0018] Figure 4 The cross-sectional profile of a shell-shaped orthodontic appliance in one embodiment of this application is schematically shown;

[0019] Figure 5 This illustration schematically demonstrates the relationship between the force value and the coverage area of ​​a shell-shaped orthodontic appliance in one embodiment of this application;

[0020] Figure 6A The diagram schematically illustrates the cross-sectional profile of a shell-shaped orthodontic appliance with an excessively large coverage area.

[0021] Figure 6B The cross-sectional profile of a shell-shaped orthodontic appliance with reduced coverage area is schematically shown in one embodiment of this application;

[0022] Figure 7 The cross-sectional profile of a shell-shaped orthodontic appliance capable of opening the bite is schematically shown in one embodiment of this application. Detailed Implementation

[0023] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof. In the drawings, similar symbols generally denote similar components unless the context otherwise requires. The illustrative embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments and variations may be employed without departing from the spirit or scope of the subject matter described herein. It should be readily understood that various different configurations, substitutions, combinations, and designs can be made to the various aspects of the present application generally described herein and illustrated in the drawings, all of which are clearly contemplated and form part of the present application.

[0024] In order to overcome the limitations of traditional hot-press molding processes on shell-shaped dental instruments, the inventors of this application have developed a method for manufacturing shell-shaped dental instruments based on 3D printing technology after extensive work.

[0025] Shell-shaped dental instruments are integral shells that form cavities to accommodate teeth, the geometry of which is essentially matched to the specific layout of the teeth.

[0026] In one embodiment, the shell-shaped dental instrument may be a shell-shaped orthodontic appliance whose geometry allows it to reposition teeth from a first layout to a second layout using the elasticity generated by deformation. In yet another embodiment, the shell-shaped dental instrument may be a shell-shaped retainer for holding teeth in their current layout.

[0027] Please refer to Figure 1 This is a schematic flowchart of a shell-shaped dental instrument manufacturing method 100 based on 3D printing technology in one embodiment of this application.

[0028] In 101, a parametric 3D digital model of a shell-shaped dental instrument is generated based on a 3D digital model of a tooth.

[0029] In one embodiment, the three-dimensional digital model of the tooth is a non-parametric three-dimensional digital model.

[0030] Non-parametric 3D digital models express geometric shapes using only geometric data and do not have parametric descriptions of geometric features. For example, non-parametric 3D digital models generally express geometric shapes using geometric data such as vertices, faces, and normals. Taking an STL (Stereolithography) file as an example, its geometric data includes the vertices of each triangular face and the coordinates of all vertices in the world coordinate system.

[0031] Parametric 3D digital models express geometric forms using both geometric data and parametric descriptions. Geometric parameters in a parametric 3D digital model can include both variable and invariant parameters. Examples of geometric parameters include thickness, curvature, radius, and positional relationships.

[0032] Modifications to the geometry of non-parametric 3D digital models can only be achieved by directly altering the geometric data. This lack of intuitive and precise control over geometric features (e.g., thickness, curvature, radius) makes targeted modifications to the geometry of a 3D digital model (e.g., obtaining specific thickness, curvature, radius) extremely difficult. In contrast, parametric 3D digital models contain not only geometric data but also parameters describing geometric features. Therefore, modifications to parametric 3D digital models can be made by changing the corresponding parameters, allowing for intuitive and precise control over the geometry of a 3D digital model.

[0033] Please refer to Figure 1A This is a schematic flowchart of 101 in one embodiment of this application.

[0034] In 1011, a three-dimensional digital model of the teeth is obtained.

[0035] In one embodiment, the shell-shaped dental instrument may be a shell-shaped orthodontic appliance, and the three-dimensional digital model of the teeth may be a three-dimensional digital model of the dentition (e.g., maxillary or mandibular dentition) in the target layout of the corresponding orthodontic step.

[0036] In another embodiment, the shell-shaped dental instrument may be a shell-shaped retainer, and the three-dimensional digital model of the tooth may be a three-dimensional digital model of the dentition (e.g., the maxillary or mandibular dentition) in a desired layout.

[0037] Orthodontic treatment using shell-shaped appliances typically involves dividing the treatment into multiple successive steps (e.g., 20 to 40 successive steps). Each step corresponds to a shell-shaped appliance used to reposition the teeth from the initial layout of that step to the target layout of that step.

[0038] In one embodiment, a shell-shaped orthodontic appliance can be fabricated based on a three-dimensional digital model of the dentition under the target layout of the corresponding orthodontic step.

[0039] In one embodiment, a series of target layouts for successive orthodontic steps can be generated based on a three-dimensional digital model of the dentition in its original layout prior to orthodontic treatment.

[0040] In one embodiment, a three-dimensional digital model of the dentition in its original layout can be obtained by directly scanning the patient's jaw. In another embodiment, a three-dimensional digital model of the dentition in its original layout can be obtained by scanning a physical model of the patient's jaw, such as a plaster cast. In yet another embodiment, a three-dimensional digital model of the dentition in its original layout can be obtained by scanning a bite impression of the patient's jaw.

[0041] In one embodiment, after obtaining a three-dimensional digital model of the dentition in its original layout, it can be segmented so that each tooth in the three-dimensional digital model is independent of the others, thereby enabling individual movement of each tooth.

[0042] In one embodiment, a series of successive intermediate layouts can be generated based on the original layout and the desired layout, i.e., the target layout of a series of successive corrective steps.

[0043] In one embodiment, a three-dimensional digital model of the dentition with a desired layout can be obtained based on a three-dimensional digital model of the dentition with a segmented original layout. In another embodiment, the three-dimensional digital model of the dentition with a segmented original layout can be manually manipulated to move each tooth to the desired position to obtain a three-dimensional digital model of the dentition with the desired layout. In yet another embodiment, a computer can be used to automatically move each tooth to the desired position based on a three-dimensional digital model of the dentition with a segmented original layout to obtain a three-dimensional digital model of the dentition with the desired layout.

[0044] In one embodiment, after obtaining the original layout and the desired layout, interpolation calculations can be performed based on the two to obtain a target layout for a series of successive corrective steps.

[0045] In another embodiment, the three-dimensional digital model of the dentition under the original layout can be manually manipulated to directly obtain the target layout of a series of successive orthodontic steps.

[0046] In another embodiment, a computer can be used to automatically generate a series of target layouts for successive orthodontic steps based on a three-dimensional digital model of the dentition under the original layout, using a specific method (e.g., spatial search method).

[0047] The most commonly used format for 3D digital models of teeth is the STL model (or STL file). The following descriptions of various embodiments of this application will use 3D digital models of teeth in STL format as examples. The STL file format is an interface protocol developed by 3DSYSTEMS in 1988, a 3D graphics file format used for rapid prototyping technology. An STL file consists of the definitions of multiple triangular facets. The definition of each triangular facet includes the 3D coordinates of each vertex of the triangle and the normal vector of the facet. An STL model is essentially a 3D shape enclosed by closed surfaces and does not have a defined thickness.

[0048] In 1013, a nonparametric 3D digital model of a shell-shaped dental instrument is generated based on a 3D digital model of a tooth.

[0049] In one embodiment, the three-dimensional digital model of a tooth can be a three-dimensional digital model of the jaw after removing the gingival portion and retaining only the crown portion.

[0050] In one embodiment, a three-dimensional digital model of the tooth can be wrapped to generate a first three-dimensional digital model that wraps the tooth. The portion of the surface of this first three-dimensional digital model corresponding to the crown is used as the inner surface of the three-dimensional digital model of the shell-shaped dental instrument. Then, based on the first three-dimensional digital model, a second three-dimensional digital model is obtained by expanding it outward along the normal direction by a predetermined distance (i.e., a predetermined thickness of the shell-shaped dental instrument). The portion of the surface of this second three-dimensional digital model corresponding to the crown is used as the outer surface of the three-dimensional digital model of the shell-shaped dental instrument. Next, the surfaces of the first and second three-dimensional digital models are combined to generate a third three-dimensional digital model, which serves as the three-dimensional digital model of the shell-shaped dental instrument. In one embodiment, the three-dimensional digital model of the shell-shaped dental instrument can be an STL model.

[0051] In 1015, the non-parametric 3D digital model of shell-shaped dental instruments is converted into a parametric 3D digital model.

[0052] In one embodiment, the parametric 3D digital model may be in IGES (Initial Graphics Exchange Specification) or STEP (Standard for the Exchange of Product Model Data) format.

[0053] In one embodiment, the parametric model of a shell-shaped dental instrument can be a parametric shell element model.

[0054] In finite element analysis, there are two commonly used models: solid element model and shell element model. For finite element analysis of thin-walled structures, the shell element model can converge to a stable solution relatively easily. Since shell-shaped dental instruments are also thin-walled structures, the shell element model in finite element analysis can be used as a reference when generating the parametric model of shell-shaped dental instruments. At the same time, thickness parameters can be assigned to them, which makes it easy to control the thickness of each part of the shell-shaped dental instrument.

[0055] In one embodiment, software such as Geomagic, HyperMesh, and 3-matic can be used to generate a parametric shell element model with thickness parameters in IGES or STEP format based on the STL model of the shell-shaped dental instrument.

[0056] In another embodiment, CAE software such as HyperMesh, LSTC, Abaqus, or Ansys can be used to directly edit the STL model of the shell-shaped dental instrument, change its data structure, and assign it parameters including thickness to obtain a parameterized shell element model.

[0057] In another embodiment, a parameterized shell unit model of a shell-shaped dental instrument can be directly generated based on the point cloud data of the STL model of the shell-shaped dental instrument.

[0058] In another embodiment, NURBS (Non-Uniform Rational B-Splines) curves and surfaces can also be used to describe the geometric features of shell-shaped dental instruments. In one embodiment, a three-dimensional model can be divided into several surfaces using NURBS curves, with multiple NURBS curves forming a single NURBS surface. Both NURBS curves and NURBS surfaces are functions, and the geometric features of the parametric three-dimensional digital model of the shell-shaped dental instrument can be altered by changing the parameters within the functions.

[0059] NURBS curves can be obtained based on point cloud fitting. A NURBS curve can serve as the common boundary of two adjacent NURBS surfaces to ensure the continuous splicing of each surface. For specific methods, please refer to "Research on NURBS Surface Reconstruction Based on Point Cloud Data" published by Zhao Jijun and Yu Chengliang in the Journal of Agricultural Machinery, Vol. 38, No. 4, 2007.

[0060] Based on the inspiration of this application, it is understood that, in addition to the parametric shell element model and NURBS curves and surfaces mentioned above, other applicable parametric three-dimensional digital models can also be used, which will not be listed here.

[0061] In 103, a parametric three-dimensional digital model of a shell-shaped dental instrument is examined.

[0062] In one embodiment, a computer can be used to determine whether the shell-shaped dental instrument it represents is qualified based on a parametric three-dimensional digital model of the shell-shaped dental instrument.

[0063] In one embodiment, for shell-type orthodontic appliances, one aspect of determining their qualification is whether they can reposition teeth from the initial layout of the corresponding orthodontic step to the target layout. Following the guidance of this application, it can be understood that the inspection of shell-type orthodontic appliances may also include, but is not limited to, the following: whether the shell-type orthodontic appliance is damaged during wear; whether the orthodontic force on the moving teeth is within an appropriate range during wear (different orthodontic movement designs and different tooth positions may require different appropriate orthodontic force ranges; if the orthodontic force is too small, it is difficult to move the moving teeth; if the orthodontic force is too large, it may damage periodontal tissues); whether the force on the anchorage teeth is reasonable during wear; whether the ratio of the translational force to the torque value on the moving teeth is within an appropriate range during wear; and whether the removal force of the appliance is excessive, etc.

[0064] In one embodiment, the parametric three-dimensional digital model of a shell-shaped dental appliance can be tested using finite element analysis. The following example illustrates this by testing whether the shell-shaped appliance can reposition the teeth from their initial layout to the target layout in the corresponding orthodontic step.

[0065] In one embodiment, finite element models of the shell-shaped dental instrument and the jaw can be generated first, based on the parametric 3D digital model of the shell-shaped dental instrument and the 3D digital model of the jaw. Then, in a finite element simulation environment, the finite element model of the shell-shaped dental instrument can be fitted onto the finite element model of the jaw. Based on the tooth layout and load borne when equilibrium is achieved, the qualification of the shell-shaped dental instrument represented by the parametric 3D digital model can be determined.

[0066] In one embodiment, when calculating the effect of a shell-shaped orthodontic appliance on tooth positioning based on finite element simulation, the osteoclast-bone biological process of the alveolar bone can be ignored to simplify the calculation.

[0067] In one embodiment, the tooth can be assumed to be absolutely rigid (i.e., without displacement), and the load on the tooth when it reaches mechanical static equilibrium can be calculated using static solution methods. Based on the calculated load, the displacement of the tooth in actual situation can be estimated, and the parametric three-dimensional digital model of the shell-shaped dental instrument can be verified based on this.

[0068] Because the periodontal ligament is an elastic body, teeth will shift due to the elastic deformation of the periodontal ligament when subjected to load. However, when the load is removed, the periodontal ligament will return to its original shape, and correspondingly, the tooth displacement will also change due to the restoration of the periodontal ligament. In another embodiment, in order to more accurately calculate the effect of the shell-shaped orthodontic appliance on tooth positioning, the influence of the elastic deformation and restoration of the periodontal ligament on the tooth positioning of the shell-shaped orthodontic appliance can be taken into account.

[0069] In another embodiment, to make the simulation results closer to reality, the osteoclastotic process of the alveolar bone can be simulated in finite element simulation. In one embodiment, the osteoclastotic process of the alveolar bone can be expressed by a function f(σ,t) that varies with time and stress distribution. In this case, the finite element model of the jaw can include finite element models of the crown, root, periodontal ligament, and alveolar bone (which can include cortical bone and cancellous bone).

[0070] For specific methods of verifying shell-shaped dental appliances using finite element analysis, please refer to Chinese Patent Application No. 201710130613.0, "Verification Method for the Manufacturing Process of Shell-Shaped Dental Instruments Based on Hot Press Film Molding Technology," filed by Wuxi Angel Medical Devices Technology Co., Ltd. on March 7, 2017, and Chinese Patent Application No. 201710130668.1, "Verification Method for the Manufacturing Process of Shell-Shaped Dental Instruments Based on Hot Press Film Molding Technology," filed on March 7, 2017, and filed in January 2017. The following patent applications were filed on January 26, 2017: Chinese Patent Application No. 201710057418.X, entitled "Inspection Method of Shell-shaped Dental Instruments Based on Computer Finite Element Analysis"; Chinese Patent Application No. 201710057403.3, entitled "Inspection Method of Accessories of Shell-shaped Dental Instruments Based on Computer Finite Element Analysis"; and Chinese Patent Application No. 201710286619.7, entitled "Inspection Method of Computer-Aided Dental Orthodontic Instruments".

[0071] In yet another embodiment, the parametric three-dimensional digital model of the shell-shaped dental instrument can be examined based on a simplified numerical model.

[0072] In one embodiment, to simplify calculations, the osteoclast-bone formation process of the alveolar bone during orthodontic treatment can be disregarded, and the tooth movement can be estimated based on the force exerted on the tooth under static mechanical equilibrium.

[0073] Please refer to Figure 2 The diagram illustrates a simplified numerical model in one embodiment of this application.

[0074] In this simplified numerical model, alveolar bone 201 (the portion of alveolar bone supporting the moving tooth), periodontal ligament 203 (the periodontal ligament covering the root of the moving tooth), moving tooth 205, shell-shaped orthodontic appliance 207, anchorage tooth 209, periodontal ligament 211 (the periodontal ligament covering the root of the anchorage tooth), and alveolar bone 213 (the portion of alveolar bone supporting the anchorage tooth) form an interacting chain.

[0075] In one embodiment, the shell-shaped appliance and periodontal ligament can be simplified into distinct springs. The parameters of each spring can be assigned based on root morphology, tooth movement design, tooth alignment, and the shape of the shell-shaped appliance. The assignment of spring parameters can be based on theoretical derivations from structural mechanics and continuity mechanics, or on a mechanics database, or on the aforementioned full-element simulation method (i.e., modeling materials, shapes, boundary conditions, etc., to reflect real-world conditions, and then performing simulations based on such a finite element model). In one embodiment, spring parameters may include tensile modulus and rotational modulus, representing the translational and rotational stiffness of the teeth, respectively. After assigning values ​​to the springs in the model, the displacement of the moving teeth under the action of the shell-shaped appliance can be calculated, allowing determination of whether the shell-shaped appliance meets the design requirements.

[0076] Based on the inspiration of this application, it is understood that, in addition to the finite element method and simplified numerical model described above, other methods such as the finite volume method, finite difference method, domain decomposition method, finite point method, and boundary element method can also be used to verify the three-dimensional digital model of shell-shaped dental instruments.

[0077] If the test results show that the shell-shaped dental instrument represented by the parametric 3D digital model is qualified, skip to 107; otherwise, skip to 105.

[0078] In 105, at least one geometric parameter of the parametric three-dimensional digital model of the shell-shaped dental instrument is modified based on the test results.

[0079] The inventors of this application have discovered that the force applied to the teeth by a shell-shaped orthodontic appliance is directly related to the cross-sectional shape and area of ​​the shell-shaped appliance. Please refer to... Figure 3 This illustration demonstrates, in one embodiment of this application, the relationship between the force exerted on the teeth by the shell-shaped orthodontic appliance in the mesiodistal and buccal-lingual directions and the cross-sectional area of ​​the shell-shaped appliance, without significant changes in the cross-sectional shape of the appliance. Curve 301 represents the relationship between the force exerted on the teeth by the shell-shaped appliance in the mesiodistal direction and the cross-sectional area of ​​the shell-shaped appliance, curve 303 represents the relationship between the force exerted on the teeth by the shell-shaped appliance in the buccal-lingual direction and the cross-sectional area of ​​the shell-shaped appliance, and interval 305 represents the ideal range of tooth force, which can be used to guide the modification of the parametric model of the shell-shaped orthodontic appliance. In one embodiment, curves 301 and 303 can be obtained through experiments or simulations using statistical methods.

[0080] In one embodiment, if the test results show that the orthodontic force on a certain tooth is too great or too small, it can be determined according to... Figure 3The curve shown adjusts the thickness of the corresponding part of the shell appliance (e.g., the part of the shell appliance that connects the tooth to the adjacent tooth) so that the orthodontic force on the tooth is in the more ideal range 305.

[0081] In one embodiment, the area on the parametric 3D digital model of the shell-shaped orthodontic appliance where the thickness needs to be adjusted can be manually selected, and the thickness parameter of the selected area can be modified. In one embodiment, the thickness parameter can be modified by directly inputting the thickness value to be increased or decreased; in another embodiment, the thickness parameter can also be modified by controlling the thickness gradient in the form of a function, making the thickness transition smoother.

[0082] The inventors of this application have discovered that the thickness of each part of a shell-shaped orthodontic appliance made based on the traditional hot-pressing film process is roughly the same. In this case, the teeth closer to the moving teeth bear greater anchorage force. This uneven distribution of anchorage may cause the anchoring teeth of adjacent moving teeth to bear excessive anchorage force or cause the moving teeth to not receive sufficient anchorage.

[0083] The inventors of this application have discovered that the force applied to a tooth by a shell-shaped orthodontic appliance is positively correlated with the thickness of the portion of the shell-shaped appliance corresponding to that tooth; the greater the thickness, the greater the force. To achieve a more rational anchorage distribution, protect anchoring teeth, and ensure orthodontic effectiveness, the thickness of the corresponding portion of the shell-shaped appliance's sidewall (covering the labial, buccal, and lingual sides of the tooth) can be adjusted to regulate the anchorage distribution.

[0084] Please refer to Figure 4 The diagram schematically illustrates the local thickness distribution of a shell-shaped orthodontic appliance in one embodiment of this application.

[0085] Tooth 401 is a movable tooth, and teeth 403, 405, and 407 are anchorage teeth. In one embodiment, to make the anchorage force borne by the anchorage teeth more balanced, the thickness of the shell-shaped orthodontic appliance can be gradually increased from the adjacent tooth 403 of the movable tooth 401 in a direction away from the movable tooth 401. This can make the anchorage force borne by the anchorage teeth 403, 405, and 407 more balanced.

[0086] As is known in the industry, different teeth can withstand different anchorage forces; for example, molars can withstand greater anchorage forces than anterior teeth. In one embodiment, the thickness of each part of the shell-shaped orthodontic appliance can be adjusted according to the anchorage capacity of different teeth, allocating greater anchorage forces to teeth with higher anchorage capacity, thereby making full and rational use of anchorage teeth.

[0087] In one embodiment, when the thickness of the parametric three-dimensional digital model of a shell-shaped dental instrument is locally adjusted, the inner surface can remain unchanged without modifying its inner surface (the surface that wraps the teeth), and the local thickness adjustment only changes the geometry of the outer surface.

[0088] The inventors of this application have discovered that, in cases of opening interdental spaces, the force exerted by a shell-shaped orthodontic appliance on the teeth is related to the area it covers. When the coverage area is too small, the shell-shaped appliance lacks sufficient points of force application, potentially resulting in insufficient force; conversely, when the coverage area is too large, the rigidity of the shell-shaped appliance at the interdental space may be insufficient, also potentially leading to insufficient force. Please refer to... Figure 5 The diagram illustrates curve 501, representing the relationship between the contact area of ​​the package and the force value, in one embodiment of this application.

[0089] Please refer to Figure 6A This illustration schematically demonstrates an example of insufficient stiffness of a shell-shaped orthodontic appliance in the interdental space due to an excessively large area covering the teeth. Because the shell-shaped appliance 601 enters the gap between teeth 603 and 605 too deeply, its area covering teeth 603 and 605 is too large, resulting in insufficient stiffness in the mesiodistal direction at the junction of teeth 603 and 605. Consequently, the force applied in the mesiodistal direction to open the gap between teeth 603 and 605 is too small. Figure 5 Within the range of 503 shown.

[0090] In one embodiment, the shape of the portion of the shell-shaped orthodontic appliance 601 connecting teeth 603 and 605 can be modified to reduce the curvature of this portion in the mesiodistal direction, making it more gradual and thus increasing its rigidity. (See also...) Figure 6B The diagram schematically shows the modified shell-shaped orthodontic appliance 601' that connects teeth 603 and 605.

[0091] In some orthodontic cases, it is necessary to open the posterior occlusion in order to facilitate the adjustment of tooth position.

[0092] In one embodiment, the testing criteria may include whether the shell appliance opens the bite to the desired degree. The parametric three-dimensional digital model of the shell appliance can be modified based on the test results, increasing the thickness of specific regions on the occlusal surface of the maxillary and / or mandibular shell appliance so that the shell appliance it represents can open the bite to the desired degree.

[0093] Please refer to Figure 7 The diagram schematically illustrates the cross-sectional profile of a shell-shaped orthodontic appliance in a buccal-lingual direction according to one embodiment of this application. To open the bite, the thickness of the occlusal surface of the maxillary shell-shaped appliance 701 corresponding to the posterior tooth 703 is increased to form an occlusal pad 705 there. Simultaneously, the thickness of the occlusal surface of the mandibular shell-shaped appliance 711 corresponding to the posterior tooth 713 is increased to form an occlusal pad 715 there. During occlusion, the occlusal pads 705 and 715 abut against each other, thereby opening the bite. In one embodiment, the occlusal pads 705 and 715 can be fitted with matching irregularities to reduce the likelihood of occlusal slippage.

[0094] After the modifications are completed, jump to step 103 to verify the parametric 3D digital model of the modified shell-shaped dental instrument. Repeat this process until a qualified parametric 3D digital model of the shell-shaped dental instrument is obtained.

[0095] In 107, 3D printing digital files are generated based on the parametric 3D digital model of the validated shell-shaped dental instrument.

[0096] Currently, the most commonly used 3D printing digital files are STL and STP formats. Although some manufacturers' 3D printing equipment supports formats such as OBJ, BREP, MAX, 3DM, 3DS, X_T, SKP, SLDPRT, PRT, ASM, F3D, FBX, RVT, and WIRE, these are relatively rare. The following example uses the conversion of a shell element model to an STL file for illustration.

[0097] In one embodiment, if the shell element is triangular, then the shell element model can be converted into an STL file by importing, converting, and exporting using preprocessing software of commercial CAE software such as HyperMesh, LSTC, Abaqus, and Ansys.

[0098] Once the parametric model is converted into an STL file, the surfaces and curves are replaced and transformed into a mesh, forming a series of triangular patches and point cloud data that represent the precise geometric meaning of the prototype.

[0099] In one embodiment, before using an STL file to control a 3D printing device to perform 3D printing, the device can be inspected and repaired to ensure that the triangular facets form a fully enclosed surface.

[0100] In 109, 3D printing digital files are used to control 3D printing equipment to create shell-shaped dental instruments.

[0101] Currently, 3D printing equipment suitable for manufacturing shell-shaped dental instruments includes Stereolithography Appearance (SLA) equipment (such as equipment provided by 3D Systems), Digital Light Processing (DLP) equipment (such as equipment provided by Envision TEC), and PolyJet equipment (such as equipment provided by Stratasys).

[0102] Once you have the 3D printing digital file, you can use it to control the 3D printing equipment to create shell-shaped dental instruments.

[0103] Although various aspects and embodiments of this application have been disclosed herein, other aspects and embodiments of this application will be apparent to those skilled in the art upon inspiration from this application. The various aspects and embodiments disclosed herein are for illustrative purposes only and not for limiting purposes. The scope and spirit of this application are determined solely by the appended claims.

[0104] Similarly, the diagrams may illustrate exemplary architectures or other configurations of the disclosed methods and systems, which aid in understanding the features and functions that may be included in the disclosed methods and systems. The claims are not limited to the exemplary architectures or configurations shown, and the desired features may be implemented using various alternative architectures and configurations. Furthermore, the order of the blocks given herein with respect to flowcharts, functional descriptions, and method claims should not be limited to various embodiments implemented in the same order to perform the said functions, unless explicitly indicated in the context.

[0105] Unless otherwise expressly stated, the terms and phrases used herein, and their variations thereof, should be interpreted as open-ended rather than restrictive. In some instances, the appearance of extended words and phrases such as “one or more,” “at least,” “but not limited to,” or other similar expressions should not be construed as an intention or necessity to indicate a narrower scope in examples where such extended expressions might not exist.

Claims

1. A method for manufacturing a shell-shaped dental instrument, comprising: Obtain a three-dimensional digital model of the teeth; A non-parametric three-dimensional digital model of a shell-shaped dental instrument is generated based on the three-dimensional digital model of the teeth. A parametric three-dimensional digital model of the shell-shaped dental instrument is generated based on the non-parametric three-dimensional digital model of the shell-shaped dental instrument. Modify the thickness parameters of a local region in the parametric three-dimensional digital model of the shell-shaped dental instrument; 3D printing digital files are generated based on the parametric 3D digital model of the modified shell-shaped dental instrument; and The aforementioned 3D printing digital file is used to control 3D printing equipment to produce shell-shaped dental instruments.

2. The method for manufacturing a shell-shaped dental instrument as described in claim 1, characterized in that, The shell-shaped dental instrument is a shell-shaped orthodontic appliance used to reposition teeth from a first layout to a second layout.

3. The method for manufacturing a shell-shaped dental instrument as described in claim 1, characterized in that, Non-parametric 3D digital models express geometric shapes using only geometric data; parametric 3D digital models express geometric shapes using both geometric data and parametric descriptions.

4. The method for manufacturing a shell-shaped dental instrument as described in claim 1, characterized in that, The parameterized three-dimensional digital model is a parameterized shell element model.

5. The method for manufacturing a shell-shaped dental instrument as described in claim 1, characterized in that, It also includes: verifying the parametric three-dimensional digital model of the shell-shaped dental instrument, wherein modifications to the parametric three-dimensional digital model of the shell-shaped dental instrument are made based on the results of the verification.

6. The method for manufacturing a shell-shaped dental instrument as described in claim 5, characterized in that, The test is based on finite element analysis.

7. The method for manufacturing a shell-shaped dental instrument as described in claim 1, characterized in that, The non-parametric 3D digital model is an STL model.

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