CN113134969A

CN113134969A - Method for manufacturing shell-shaped dental instrument

Info

Publication number: CN113134969A
Application number: CN202010067433.4A
Authority: CN
Inventors: 曾鹏
Original assignee: Shanghai Kuohong Information Technology Co ltd
Current assignee: Shanghai Kuohong Information Technology Co ltd
Priority date: 2020-01-20
Filing date: 2020-01-20
Publication date: 2021-07-20
Also published as: WO2021147335A1

Abstract

One aspect of the present application provides a shell-like dental instrument manufacturing method, comprising: acquiring a three-dimensional digital model of a tooth; generating a non-parametric three-dimensional digital model of a shell-like dental appliance based on the three-dimensional digital model of the teeth; generating a parameterized three-dimensional digital model of a shell-like dental appliance based on the non-parameterized three-dimensional digital model of the shell-like dental appliance; modifying at least one geometric parameter of a parameterized three-dimensional digital model of the shell-like dental instrument; generating a 3D printed digital file based on the modified parameterized three-dimensional digital model of the shell-like dental instrument; and controlling a 3D printing device to manufacture a shell-shaped dental instrument by using the 3D printing digital file.

Description

Method for manufacturing shell-shaped dental instrument

Technical Field

The present application relates generally to shell-like dental instrument fabrication methods, and more particularly to shell-like dental instrument fabrication methods based on 3D printing techniques.

Background

Shell-like dental instruments (e.g., shell appliances, shell holders, etc.) based on polymeric materials are becoming increasingly popular for their aesthetic, convenience, and cleaning benefits.

The conventional method for manufacturing the shell-shaped dental instrument is based on a hot-press molding process, however, the limitations of the process itself impose limitations on various aspects of the shell-shaped dental instrument.

In view of the above, there is a need to develop a new method for manufacturing a shell-shaped dental instrument, so as to get rid of the limitations of the traditional process on the shell-shaped dental instrument.

Disclosure of Invention

In some embodiments, the shell-like dental appliance may be a shell-like appliance for repositioning teeth from a first arrangement to a second arrangement.

In some embodiments, the non-parametric three-dimensional digital model expresses geometry solely in geometric data; the parameterized three-dimensional digital model expresses geometry in both geometric data and a parametric description.

In some embodiments, the geometric parameter comprises thickness.

In some embodiments, the parameterized three-dimensional digital model may be a parameterized shell element model.

In some embodiments, the method for manufacturing a shell-shaped dental instrument may further include: inspecting the parameterized three-dimensional digital model of the shell-like dental instrument, wherein the modification of the parameterized three-dimensional digital model of the shell-like dental instrument is performed based on the results of the inspection.

In some embodiments, the inspection may be based on finite element analysis.

In some embodiments, the non-parametric three-dimensional digital model may be an STL model.

Drawings

The above-described and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. It is appreciated that these drawings depict only several embodiments of the disclosure and are therefore not to be considered limiting of its scope, for the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

FIG. 1 is a schematic flow chart of a method of making a shell-like dental instrument in one embodiment of the present application;

FIG. 1A is a schematic flow chart of the generation of a parameterized three-dimensional digital model of a shell-like dental appliance based on a three-dimensional digital model of a tooth in one embodiment of the present application;

FIG. 2 schematically illustrates a simplified numerical model in one embodiment of the present application;

FIG. 3 schematically illustrates the force value versus cross-sectional area of a shell appliance in one embodiment of the present application;

FIG. 4 schematically illustrates a cross-sectional profile of a shell appliance in one embodiment of the present application;

FIG. 5 schematically illustrates the force value versus area of the wrap for a shell appliance in one embodiment of the present application;

FIG. 6A schematically illustrates a cross-sectional profile of a shell appliance with an oversized packing area;

FIG. 6B schematically illustrates a cross-sectional profile of a shell appliance of one embodiment of the present application with a reduced packing area;

FIG. 7 schematically illustrates a cross-sectional profile of a shell appliance capable of opening a bite in one embodiment of the present application.

Detailed Description

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, like reference numerals generally refer to like parts throughout the various views unless the context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter described herein. It should be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.

In order to overcome the limitations of the traditional hot-pressing film forming process on various aspects of the shell-shaped dental instrument, the inventor of the application develops a shell-shaped dental instrument manufacturing method based on a 3D printing technology through a great deal of work.

Shell-like dental appliances are one-piece shell-like, forming a cavity for receiving a tooth, the geometry of the cavity substantially matching that of a particular arrangement of teeth.

In one embodiment, the shell-like dental appliance may be a shell-like appliance having a geometry such that it can reposition teeth from a first configuration to a second configuration using the elastic forces created by the deformation. In yet another embodiment, the shell-like dental instrument may be a shell-like holder for holding the teeth in the current arrangement.

Referring to fig. 1, a schematic flow chart of a method 100 for manufacturing a shell-shaped dental instrument based on 3D printing technology in an embodiment of the present application is shown.

In 101, a parameterized three-dimensional digital model of a shell-like dental appliance is generated based on the three-dimensional digital model of the teeth.

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

The non-parametric three-dimensional digital model expresses geometry only in geometric data and has no parametric description of geometric features. For example, the non-parametric three-dimensional digital model generally expresses geometric data such as vertices, patches, normal vectors, etc., and takes an stl (stereo) file as an example, the geometric data includes vertices of each triangle patch and coordinate values of all the vertices in the world coordinate system.

The parameterized three-dimensional digital model expresses geometry in both geometry data and a parametric description. The geometric parameters in the parameterized three-dimensional digital model may include variable parameters and invariant parameters. Examples of geometric parameters include thickness, curvature, radius, positional relationship, and the like.

The modification of the geometry of the non-parametric three-dimensional digital model can only be achieved by directly modifying the geometry data, and the geometric features (e.g., thickness, curvature, radius, etc.) cannot be controlled intuitively and accurately, which makes it very difficult to modify the geometry of the three-dimensional digital model in a targeted manner (e.g., to obtain a specific thickness, curvature, radius, etc.). In contrast, since the parameterized three-dimensional digital model not only contains geometric data but also contains parameters describing geometric features, the target geometric form can be intuitively and accurately obtained by modifying the corresponding parameters for modifying the parameterized three-dimensional digital model, so that the control on the geometric form of the three-dimensional digital model is very convenient, intuitive and accurate.

Please refer to fig. 1A, which is a schematic flowchart of an embodiment 101 of the present application.

At 1011, a three-dimensional digital model of the tooth is acquired.

In one embodiment, the shell-like dental appliance may be a shell 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 a target layout corresponding to the step of the appliance.

In yet another embodiment, the shell-like dental appliance may be a shell-like holder 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 a desired arrangement.

The shell-shaped appliance is used for orthodontic correction, generally, correction is divided into a plurality of successive correction steps (for example, 20-40 successive correction steps), and each correction step corresponds to one shell-shaped appliance and is used for repositioning teeth from an initial layout of the correction step to a target layout of the correction step.

In one embodiment, the shell appliance may be fabricated based on a three-dimensional digital model of the dentition under the target layout corresponding to the corrective step.

In one embodiment, a target layout for a series of successive corrective steps can be generated based on a three-dimensional digital model of the dentition under the original layout prior to orthodontic treatment.

In one embodiment, a three-dimensional digital model of the dentition in the original layout may be obtained by directly scanning the patient's dental jaws. In yet another embodiment, a three-dimensional digital model of the dentition in the original layout may be obtained by scanning a solid model, such as a plaster model, of the patient's dental jaw. In yet another embodiment, a three-dimensional digital model of the dentition in the original layout may be obtained by scanning the bites of the patient's jaws.

In one embodiment, after the three-dimensional digital model of the dentition in the original layout is obtained, it may be segmented such that the teeth in the three-dimensional digital model are independent of each other, thereby enabling individual movement of each tooth.

In one embodiment, a series of successive intermediate layouts, i.e., a series of successive orthodontic step target layouts, may be generated based on the original layout and the desired layout.

In one embodiment, a three-dimensional digital model of the dentition in the desired layout may be obtained based on the segmented three-dimensional digital model of the dentition in the original layout. In one embodiment, the three-dimensional digital model of the dentition in the segmented original layout may be manually manipulated to move each tooth to a desired position to obtain the three-dimensional digital model of the dentition in the desired layout. In yet another embodiment, a three-dimensional digital model of the dentition in the desired layout may be obtained using a computer by automatically moving each tooth to the desired position based on the three-dimensional digital model of the dentition in the segmented original layout.

In one embodiment, after obtaining the original layout and the desired layout, interpolation may be performed based on both to obtain a series of successive targeted layouts for the correction step.

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

In yet another embodiment, a computer may be used to automatically generate a series of successive orthodontic step target layouts based on a three-dimensional digital model of the dentition under the original layout using a particular method (e.g., a spatial search method).

A more common format for a three-dimensional digital model of teeth is an STL model (or STL file), and the following describes embodiments of the present application with reference to a three-dimensional digital model of teeth in the STL format. The STL file format is an interface protocol established by 3D SYSTEMS in 1988, and is a three-dimensional graphics file format that serves rapid prototyping technology. The STL file is comprised of a plurality of definitions of triangle patches, each of which includes three-dimensional coordinates of each vertex of the triangle and a normal vector of the triangle patch. The STL model is essentially a three-dimensional body bounded by closed surfaces, which has no thickness definition.

At 1013, a non-parametric three-dimensional digital model of the shell-like dental appliance is generated based on the three-dimensional digital model of the teeth.

In one embodiment, the three-dimensional digital model of the teeth may be a three-dimensional digital model of the jaws that retains only the crown portion after removal of the gum portion.

In one embodiment, the three-dimensional digital model of the tooth may be subjected to a wrapping operation to generate a first three-dimensional digital model of the wrapped three-dimensional digital model of the tooth, and a portion of a surface of the first three-dimensional digital model corresponding to the crown may be used as an inner surface of the three-dimensional digital model of the shell-like dental instrument. Then, a second three-dimensional digital model is obtained based on the first three-dimensional digital model by outwardly expanding a predetermined distance (i.e., the set thickness of the shell-shaped dental instrument) in the normal direction, and a portion of the surface of the second three-dimensional digital model corresponding to the crown is made to be 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 produce a third three-dimensional digital model as a shell-like dental instrument three-dimensional digital model. In one embodiment, the shell-like dental instrument three-dimensional digital model may be an STL model.

In 1015, the non-parametric three-dimensional digital model of the shell dental appliance is converted to a parametric three-dimensional digital model.

In one embodiment, the parameterized three-dimensional numerical Model may be in IGES (initiative Graphics Exchange Specification) or STEP (Standard for the Exchange of Product Model data) format.

In one embodiment, the parameterized model of the shell-like dental instrument may be a parameterized shell element model.

In finite element analysis, there are two common models, one is a solid element model and the other is a shell element model. For finite element analysis of thin-walled structures, it is relatively easy to converge to a stable solution using the shell element model. Because the shell-shaped dental instrument is also of a thin-wall structure, when a parameterized model of the shell-shaped dental instrument is generated, a shell unit model in finite element analysis can be used for reference, and meanwhile, thickness parameters can be given to the shell unit model, so that the thickness of each part of the shell-shaped dental instrument can be conveniently controlled.

In one embodiment, a parameterized shell element model with thickness parameters in IGES or STEP format may be generated based on the STL model of the shell-like dental instrument using Geomagic, Hypermesh, 3-matic, etc. software.

In yet another embodiment, the STL model of the shell-like dental instrument can be directly edited by CAE software such as HyperMesh, LSTC, Abaqus or Ansys, and the parameterized shell element model can be obtained by changing the data structure and assigning parameters including the thickness to the model.

In yet another embodiment, the parameterized shell element model of the shell-like dental instrument may be generated directly based on point cloud data of the STL model of the shell-like dental instrument.

In yet another embodiment, NURBS (Non-Uniform Rational B-Splines) curves and surfaces may also be used to describe the geometry of shell-like dental instruments. In one embodiment, a three-dimensional model may be divided into a number of curved surfaces using NURBS curves, and the NURBS curves enclose a NURBS curved surface. The NURBS curve and the NURBS surface are functional forms, and the geometric characteristics of the shell-shaped dental appliance parameterized three-dimensional digital model can be changed by changing parameters in the functions.

The NURBS curve can be obtained based on point cloud fitting, and one NURBS curve can be used as a common boundary of two adjacent NURBS curved surfaces so as to ensure continuous splicing of the curved surfaces. The specific method can be referred to the "NURBS curved surface reconstruction research based on point cloud data" published in agricultural machinery journal 2007 No. 38, No. 4 by Zhaojun and Yuanhuang.

It will be appreciated in the light of the present application that other suitable parameterized three dimensional numerical models may be employed in addition to the above mentioned parameterized shell element models and NURBS curves and surfaces, and are not exhaustive herein.

In 103, a parameterized three-dimensional digital model of the shell-like dental instrument is examined.

In one embodiment, a computer may be used to determine whether a shell-like dental instrument represented by the shell-like dental instrument is acceptable based on a parameterized three-dimensional digital model of the shell-like dental instrument.

In one embodiment, for a shell appliance, one way to determine if it is acceptable is to see if it can reposition teeth from an initial placement corresponding to the step of the appliance to a target placement. It will be appreciated in light of the present application that the tests for shell appliances may also include, but are not limited to, the following: whether the shell-shaped appliance is damaged or not in the wearing process; in the wearing process, whether the orthodontic force born by the movable teeth is in a proper interval (different orthodontic movement designs, different tooth positions and required proper orthodontic force intervals can be different, if the orthodontic force is too small, the movable teeth are not easy to move, and if the orthodontic force is too large, periodontal tissues can be damaged); whether the stress of the anchorage tooth is reasonable or not in the wearing process; in the wearing process, whether the ratio of the translation force value and the moment value born by the moving teeth is in a proper interval or not is judged; whether the extraction force of the appliance is too large, etc.

In one embodiment, a parametric three-dimensional digital model of a shell-like dental instrument can be examined using finite element analysis. The following description will be given by taking as an example the detection as to whether the shell-shaped appliance can reposition teeth from the initial arrangement corresponding to the correction step to the target arrangement.

In one embodiment, the shell-like dental instrument and the finite element model of the dental jaw may be generated based on the parameterized three-dimensional digital model of the shell-like dental instrument and the three-dimensional digital model of the dental jaw, respectively. Then, the shell-shaped dental instrument can be worn on the finite element model of the jaw under the finite element simulation environment, and whether the shell-shaped dental instrument represented by the parameterized three-dimensional digital model is qualified or not is judged based on the layout of the teeth and the load borne when the balance is achieved.

In one embodiment, the effect of the shell appliance in positioning the teeth is calculated based on finite element simulations, and the osteoclastogenesis biology of the alveolar bone may not be considered for simplicity of the calculation.

In one embodiment, the tooth may be assumed to be absolutely rigid (i.e., not displaced), the load of the tooth at which mechanical static equilibrium is achieved is calculated using a statics solution, the displacement of the tooth in an actual situation is estimated based on the calculated load, and a parameterized three-dimensional digital model of the shell-like dental appliance is examined based thereon.

Since the periodontal ligament is an elastic body, when a load is applied to the tooth, the tooth is displaced by elastic deformation of the periodontal ligament, but when the load is removed, the periodontal ligament is restored to its original shape, and accordingly, the displacement of the tooth is also changed by the restoration of the periodontal ligament. In yet another embodiment, to more accurately calculate the effect of the shell appliance in positioning teeth, the effect on the shell appliance in positioning teeth due to elastic deformation and recovery of the periodontal ligament can be factored in.

In yet another embodiment, in order to make the simulation result closer to reality, the osteoclastogenesis biological process of alveolar bone can be simulated in finite element simulation. In one embodiment, the osteoclastogenesis biological process of alveolar bone may be expressed as a function f (σ, t) that varies with time and stress distribution. At this time, the finite element model of the jaw may include finite element models of a crown, a root, a periodontal ligament, and an alveolar bone (which may include a cortical bone and a cancellous bone).

As a specific method for inspecting the shell-shaped appliance by using finite element analysis, reference may be made to "method for verifying the manufacturing process of the shell-shaped dental appliance based on the thermoforming technique" of Chinese patent application No. 201710130613.0, which was filed by the national institute of technology, science and technology Limited in 2017 on 3/7, in 2017, in application No. 201710130668.1, which was filed by the national institute of technology, in 2017 on 3/7, in application No. 201710057418, in Chinese patent application No. 201710057418, which was filed by 26, in 2017, in application No. 201710057403.3, in Chinese patent application No. 2017, in 26, in application No. 201710057403.3, in inspection method of the attachment of the shell-shaped dental appliance based on computer finite element analysis "of the shell-shaped dental appliance, and chinese patent application No. 201710286619.7, filed on 27/4/2017, entitled "method for testing computer-aided orthodontic appliances".

In yet another embodiment, a parameterized three-dimensional digital model of the shell-like dental appliance may be verified based on the simplified numerical model.

In one embodiment, to simplify the calculation, the movement of the tooth can be estimated based on the stress of the tooth under mechanical static equilibrium, without considering the biological process of osteoclastogenesis of alveolar bone during the correction process.

Referring to fig. 2, a simplified numerical model in one embodiment of the present application is schematically illustrated.

In this simplified numerical model, alveolar bone 201 (the portion of alveolar bone supporting the mobile tooth), periodontal ligament 203 (the periodontal ligament covering the mobile tooth root), mobile tooth 205, shell appliance 207, anchorage tooth 209, periodontal ligament 211 (the periodontal ligament covering the anchorage tooth root), and alveolar bone 213 (the portion of alveolar bone supporting the anchorage tooth) form a chain of interactions.

In one embodiment, the shell appliance and periodontal ligament can be simplified as distinct springs, and the parameters of each spring can be assigned by root configuration, tooth movement design, tooth arrangement position, and shell appliance configuration. The assignment of the spring parameters can be based on theoretical derivation of structural mechanics and continuous mechanics, can also be based on a mechanics database, and can also be based on the above full-element simulation method (namely, modeling conforming to real conditions is carried out on materials, forms, boundary conditions and the like, and simulation is carried out on the basis of the finite element model). In one embodiment, the spring parameters may include a tensile modulus and a rotational modulus characterizing the stiffness of the tooth in translation and rotation, respectively. After the springs in the model are assigned, the displacement generated by moving the teeth under the action of the shell-shaped appliance can be calculated, and whether the shell-shaped appliance meets the design requirements can be judged based on the displacement.

In the light of the present application, it is understood that, in addition to the Finite element Method and the simplified numerical model described above, the three-dimensional digital model of the shell-shaped dental instrument may be examined by using a Finite Volume Method (Finite Volume Method), a Finite Difference Method (Finite Difference Method), a region decomposition Method, a Finite point Method, a boundary element Method, and the like.

And jumping to 107 if the test result shows that the shell-shaped dental instrument represented by the parameterized three-dimensional digital model is qualified, and jumping to 105 if the test result shows that the shell-shaped dental instrument represented by the parameterized three-dimensional digital model is not qualified.

In 105, at least one geometric parameter of the parameterized three-dimensional digital model of the shell-like dental instrument is modified depending on the examination result.

The inventors of the present application have found that the force applied to the teeth by the shell-shaped appliance is directly related to the cross-sectional shape and cross-sectional area of the shell-shaped appliance. Referring to fig. 3, a relationship between force values of the shell-shaped appliance and cross-sectional areas of the shell-shaped appliance, which are borne by teeth in the mesial-distal direction and the bucco-lingual direction, is shown in an embodiment of the present application on the premise that the cross-sectional morphology of the shell-shaped appliance does not change greatly. Wherein, curve 301 represents the relationship between the force value of the shell-shaped appliance born by the teeth in the mesial-distal direction and the cross-sectional area of the shell-shaped appliance, curve 303 represents the relationship between the force value of the shell-shaped appliance born by the teeth in the bucco-lingual direction and the cross-sectional area of the shell-shaped appliance, and interval 305 represents an ideal tooth stress range, which can be used for guiding the modification of the parameterized model of the shell-shaped appliance. In one embodiment, curves 301 and 303 may be derived experimentally or by simulation, using statistical methods.

In one embodiment, if the inspection result indicates that the orthodontic force of a certain tooth is too large or too small, the thickness of the corresponding portion of the shell-shaped appliance (e.g., the portion of the shell-shaped appliance connecting the tooth and the adjacent tooth) can be adjusted according to the curve shown in fig. 3, so that the orthodontic force of the tooth is in the more ideal zone 305.

In one embodiment, the thickness parameter of the selected region can be modified by manually selecting the region of the parameterized three-dimensional digital model of the shell appliance where the thickness is to be adjusted. In one embodiment, the modification to the thickness parameter may be a direct input of a thickness value that needs to be increased or decreased; in yet another embodiment, the modification of the thickness parameter may also be a function of controlling the thickness gradient such that the transition in thickness is smoother.

The inventors of the present application have found that the thickness of each portion of the shell-shaped appliance fabricated based on the conventional hot-pressing process is approximately the same, and in this case, the greater the anchorage force to the teeth closer to the moving tooth, the more the anchorage force to the teeth closer to the moving tooth is, the uneven distribution of the anchorage force may cause the anchorage tooth adjacent to the moving tooth to receive the excessive anchorage force or cause the moving tooth not to receive sufficient anchorage force.

The inventor of the application finds that the force value applied to one tooth by the shell-shaped appliance is positively correlated with the thickness of the part of the shell-shaped appliance corresponding to the tooth, and the larger the thickness is, the larger the force value is. In order to ensure that the anchorage distribution is more reasonable, so as to protect the anchorage teeth and ensure the correction effect, the thickness of the corresponding part of the lateral wall (covering the labial and lingual sides of the teeth) of the shell-shaped corrector can be adjusted to achieve the purpose of adjusting the anchorage distribution.

Referring to FIG. 4, a partial thickness profile of a shell appliance in one embodiment of the present application is schematically illustrated.

Tooth 401 is a mobile tooth and

teeth

403, 405, and 407 are all anchorage teeth. In one embodiment, to make the anchorage force borne by the anchorage tooth more balanced, the thickness of the shell-shaped appliance may be gradually increased from the adjacent tooth 403 of the mobile tooth 401 in the direction away from the mobile tooth 401, so that the anchorage forces borne by the

anchorage teeth

403, 405, and 407 are more balanced.

As is known in the art, different teeth can bear different anchorage forces, for example, molars can bear greater anchorage forces than front teeth. In one embodiment, the thickness of each portion of the shell-shaped appliance can be adjusted according to the anchorage bearing capacity of different teeth, and greater anchorage force is allocated to the teeth with large anchorage bearing capacity, so that the anchorage teeth are fully and reasonably utilized.

In one embodiment, the inner surface can be kept unchanged without requiring modifications to its inner surface (the surface that wraps around the tooth) while locally adjusting the thickness of the parameterized three-dimensional digital model of the shell-like dental implement, the local thickness adjustment only changing the geometry of the outer surface.

The inventors of the present application have found that the amount of force applied by the shell appliance to a tooth in the case of an open tooth space is related to the area it covers the tooth. When the wrapping area is too small, the shell-shaped appliance lacks enough force application points on the teeth, which may cause insufficient force application; when the contact area of the wrapping is too large, the rigidity of the shell-shaped appliance at the position of the tooth gap may be insufficient, and finally, the force application may also be insufficient. Referring to FIG. 5, a graph 501 representing the relationship between the contact area of a package and a force value in one embodiment of the present application is schematically illustrated.

Referring to fig. 6A, an example of insufficient stiffness of a shell appliance in an interproximal region due to an excessive wrapping area of the teeth is schematically illustrated. Since the shell-shaped appliance 601 enters too deeply into the gap between the

teeth

603 and 605, the area of the shell-shaped appliance covering the

teeth

603 and 605 is too large, so that the portion connecting the

teeth

603 and 605 has insufficient rigidity in the mesial-distal direction, and the force applied by the shell-shaped appliance in the mesial-distal direction for opening the gap between the

teeth

603 and 605 is too small to be located within the interval 503 shown in fig. 5.

In one embodiment, the configuration of the portion of the shell appliance 601 between the connecting

teeth

603 and 605 can be modified to reduce the curvature of the portion in the mesial-distal direction, making it more gradual, thereby increasing its stiffness. Referring to FIG. 6B, a modified shell appliance 601' is schematically shown connecting

teeth

603 and 605.

In some orthodontic cases, it is necessary to open the posterior occlusion in order to adjust the pose of the teeth.

In one embodiment, the condition of the verification may include whether the shell appliance opens the bite to a desired extent. The parameterized three-dimensional digital model of the shell appliance may be modified according to the results of the examination to increase the thickness of specific regions of 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 extent.

Referring to FIG. 7, a cross-sectional profile of a shell appliance is schematically illustrated as viewed along the bucco-lingual direction in one embodiment of the present application. To open the occlusion, the thickness of the maxillary shell appliance 701 is increased in the area of the occlusal surface corresponding to the posterior teeth 703 so that it forms an occlusion pad 705 there, while the thickness of the mandibular shell appliance 711 is increased in the area of the occlusal surface corresponding to the posterior teeth 713 so that it forms an occlusion pad 715 there. When snapped, bite pads 705 and 715 abut, thereby opening the bite. In one embodiment, bite pads 705 and 715 may be shaped to match each other to reduce the chance of slippage of the bite.

And after the modification is finished, jumping to 103 to check the modified parameterized three-dimensional digital model of the shell-shaped dental appliance, and repeating the steps until a qualified parameterized three-dimensional digital model of the shell-shaped dental appliance is obtained.

In 107, a 3D printed digital file is generated based on the parameterized three-dimensional digital model of the shell-like dental instrument that passes the examination.

Currently, the more common 3D printed digital files are STL and STP format files. Although some 3D printing apparatuses of manufacturers support format files such as OBJ, BREP, MAX, 3DM, 3DS, X _ T, SKP, SLDPRT, PRT, ASM, F3D, FBX, RVT, WIRE, and the like, it is rare. The following embodiment will be described by taking a case unit model to STL file as an example.

In one embodiment, if the shell element is a triangle, the conversion of the shell element model to the STL file can be realized by importing, converting and exporting through preprocessing software of CAE business software such as HyperMesh, LSTC, Abaqus and Ansys.

After the parameterized model is converted to 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 exact geometric meaning of the prototype.

In one embodiment, the 3D printing device may be detected and repaired before controlling it to perform 3D printing using the STL file to ensure that the triangular patches form a fully enclosed surface.

In 109, the 3D printing device is controlled to fabricate a shell-shaped dental appliance using the 3D printed digital file.

Currently, 3D printing devices suitable for making shell-like dental instruments include Stereolithography (SLA) devices (such as those provided by 3D Systems, inc.), Digital Light Processing (DLP) devices (such as those provided by Envision TEC, inc.), and polymer jet (PolyJet) devices (such as those provided by Stratasys, inc.), among others.

After the 3D printed digital file is obtained, it can be used to control a 3D printing device to make a shell-like dental instrument.

While various aspects and embodiments of the disclosure are disclosed herein, other aspects and embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification. The various aspects and embodiments disclosed herein are for purposes of illustration only and are not intended to be limiting. The scope and spirit of the application are to be determined only by the claims appended hereto.

Likewise, the various diagrams may illustrate an exemplary architecture or other configuration of the disclosed methods and systems that is useful for understanding the features and functionality that may be included in the disclosed methods and systems. The claimed subject matter is not limited to the exemplary architectures or configurations shown, but rather, the desired features can be implemented using a variety of alternative architectures and configurations. In addition, to the extent that flow diagrams, functional descriptions, and method claims do not follow, the order in which the blocks are presented should not be limited to the various embodiments which perform the recited functions in the same order, unless the context clearly dictates otherwise.

Unless otherwise expressly stated, the terms and phrases used herein, and variations thereof, are to be construed as open-ended as opposed to limiting. In some instances, the presence of an extensible term or phrases such as "one or more," "at least," "but not limited to," or other similar terms should not be construed as intended or required to imply a narrowing in instances where such extensible terms may not be present.

Claims

1. A shell-like dental instrument fabrication method, comprising:

acquiring a three-dimensional digital model of a tooth;

generating a non-parametric three-dimensional digital model of a shell-like dental appliance based on the three-dimensional digital model of the teeth;

generating a parameterized three-dimensional digital model of a shell-like dental appliance based on the non-parameterized three-dimensional digital model of the shell-like dental appliance;

modifying at least one geometric parameter of a parameterized three-dimensional digital model of the shell-like dental instrument;

generating a 3D printed digital file based on the modified parameterized three-dimensional digital model of the shell-like dental instrument; and

and controlling a 3D printing device to manufacture a shell-shaped dental instrument by using the 3D printing digital file.

2. The method of making a shell-like dental appliance of claim 1, wherein the shell-like dental appliance is a shell appliance for repositioning teeth from a first arrangement to a second arrangement.

3. A shell-like dental instrument manufacturing method according to claim 1, wherein the non-parametric three-dimensional digital model expresses the geometric form only in geometric data; the parameterized three-dimensional digital model expresses geometry in both geometric data and a parametric description.

4. A shell-like dental instrument fabrication method as in claim 1, wherein the geometric parameter comprises thickness.

5. A shell-like dental instrument fabrication method according to claim 4, wherein the parameterized three-dimensional digital model is a parameterized shell element model.

6. A method of making a shell-like dental instrument as in claim 1, further comprising: inspecting the parameterized three-dimensional digital model of the shell-like dental instrument, wherein the modification of the parameterized three-dimensional digital model of the shell-like dental instrument is performed based on the results of the inspection.

7. A shell-like dental instrument manufacturing method according to claim 6, wherein said inspection is based on finite element analysis.

8. A shell-like dental instrument fabrication method according to claim 1, wherein the non-parametric three-dimensional digital model is an STL model.