CN-121989456-A - Anisotropic stress application unit of invisible appliance and additive manufacturing method thereof

CN121989456ACN 121989456 ACN121989456 ACN 121989456ACN-121989456-A

Abstract

The invention belongs to the technical field of digital orthodontic medical equipment and additive manufacturing, and discloses an anisotropic stressing unit of an invisible appliance and an additive manufacturing method thereof, wherein the unit comprises a miniaturized rigid base structure positioned at the gingival end and a parameterized mechanical control panel connected above the structure; the anisotropic biomechanical response of the unit is given by optimizing wave geometry and material properties through deep nerve operators (FNO), longitudinal waves provide constant horizontal resilience force for closing and developing gaps by using accordion effect, transverse waves provide vertical thrust force for depressing or elevating teeth by using Euler buckling restrained brace effect, and oblique waves and asymmetric stiffness distribution on the buccal side are used for generating composite vector force and couple moment. The invention breaks through the limitation of the traditional hot-pressing film process, realizes the high-rigidity structure molding under the limit size of 0.5mm, and converts the passive gap maintainer into an active intelligent treatment system.

Inventors

LU HAIPING
WU MENGJIE
YANG ZIYUAN
ZHANG JIANAN
ZHANG MENGHAN
Xia Jueyao
LU XIAO

Assignees

浙江博凡健康管理有限公司

Dates

Publication Date: 20260508
Application Date: 20260312

Claims (10)

1. A method of additive manufacturing of an anisotropic force application for a concealed appliance, the method comprising the steps of: Firstly, intelligent gap recognition and three-dimensional space reconstruction are carried out, a high-precision three-dimensional digital model of a patient oral cavity is obtained, a tooth extraction gap in a dentition or a tooth missing region with the width larger than a preset threshold value is automatically positioned by utilizing a geometric feature recognition algorithm, a closed curved surface shell for connecting adjacent teeth on two sides of the gap is generated based on the region, and the closed curved surface shell is defined as the virtual mechanical functional region; Step two, constructing a miniaturized high-moment-of-inertia substrate, and constructing an edge reinforcing structure which extends towards the deep part of gum and slightly warps outwards in the neck edge region of the virtual mechanical function region to form a rigid closed-loop structure with a micro-curled cross section; Generating reverse mechanical waveforms based on digital twinning, and generating parameterized wave-shaped structures on the surface of the virtual mechanical functional area by utilizing a pre-trained deep neural operator (FNO) or a finite element reverse solving algorithm based on a preset clinical correction target vector, wherein the vector comprises the magnitude, the direction and the action point of force, and the wave-shaped structures consist of continuously alternating wave crests and wave troughs, and the grain trend angles of the wave-shaped structures Wavelength of Amplitude of wave Local wall thickness distribution field Dynamically generating according to a target mechanical response curve, and endowing the virtual mechanical functional area with anisotropic elastic modulus with obvious differences in the vertical direction, the near-far middle direction and the tangential direction; Step four, the stress application unit is manufactured in a materialization way, design model data comprising the rigid closed-loop structure and the wavy structure are led out, and the invisible appliance is manufactured in any one of the following forming modes: the method comprises the steps of integrally forming additive manufacturing, converting a design model into voxel data containing material attribute information, and directly manufacturing an invisible appliance by utilizing a high-precision photo-curing 3D printing process and matching with a high-sensitive resin material; And secondly, hot-press film re-engraving and forming, namely manufacturing a solid dental die with corresponding wavy and micro-curling characteristics by using additive manufacturing or numerical control processing technology, then adopting an orthodontic film to carry out hot-press forming under the condition of heating and pressurizing, and re-engraving the wavy structure and the rigid closed-loop structure on the film.
2. The method for manufacturing an anisotropic force additive for an invisible appliance according to claim 1, wherein in the second step, in order to adapt to a patient with a shallow vestibular sulcus and improve wearing comfort, and overcome the forming limit of the traditional hot-pressing film process, the geometric parameters of the edge reinforcing structure are set as the edge extension amount The value range is less than or equal to 0.15mm Less than or equal to 1.5mm, is used for providing enough alveolar bone coating and retention under the ultra-shallow vestibular canal depth; The cross-sectional moment of inertia of the rigid closed-loop structure By varying the radius of curvature of the upturned bead at the end Make adjustments to at When the minimum value is 0.15mm, the flexural rigidity not lower than the preset threshold value can be still maintained by matching with the high-modulus photosensitive resin material 。
3. The method of anisotropic force additive manufacturing of an invisible appliance according to claim 1, wherein in step three, the texture trend angle of the wave-shaped structure The included angle between the tangential direction of the ridge line and the occlusal plane is defined as three implementation modes to correspond to different clinical correction functions: Mode one, gap closing mode, namely constructing a longitudinal wave structure and setting About 90 °, forming said functional body into a telescopic accordion-like elastic structure in the mesial-distal direction, providing a gentle return force for pulling tooth movement; mode two, the mode of supporting and maintaining the gap is that a transverse wave structure is constructed and set When the therapeutic target is to develop a gap, the wave crest of the transverse wave structure is configured as a compression-resistant strut, and the Euler critical buckling load of the structure is improved, so that the structure generates active thrust without side wall collapse under the compression state; mode three, vector force control mode, namely constructing an oblique wave structure and setting And decomposing the deformation in a single direction into a vertical component and a horizontal component by utilizing the anisotropic constitutive relation of the material to generate a composite correction force vector.
4. The method of additive manufacturing of an anisotropic force application of a contact appliance of claim 1, wherein in step three, the buccal and lingual surfaces of the virtual mechanical function area are configured to have an asymmetric wave parameter distribution; specifically, the wave structure of the buccal surface is configured to have a first stiffness by adjusting the geometric parameters or material properties of the wave structure Configuring the wave structure of the lingual surface to have a second stiffness And a first rigidity Second stiffness ; The stiffness difference When the appliance is deformed under force, the action line of the combined force deviates from the impedance center of the target tooth, so that a moment of couple is generated, and the moment of couple is used for controlling the tooth root torque of adjacent teeth at two sides of a gap or generating rotary movement, so that the teeth are prevented from inclining in the moving process.
5. The method of additive manufacturing for anisotropic force application of an invisible appliance according to claim 1, wherein in step three, the generation of the inverse mechanical waveform based on digital twinning specifically comprises: establishing a digital twin multi-physical field coupling model comprising teeth, periodontal ligament and appliance; defining a target correction force function Wherein Displacement amount for gap closure or development; learning wave geometry parameters using Fourier Neural Operators (FNO) A nonlinear mapping relationship with the mechanical response; input target correction force function The optimal geometric parameter combination is solved through a counter-propagation or optimization algorithm, so that the generated stress application unit outputs constant correction force within a preset displacement range, and the predicted stress peak value is lower than the yield strength of the material, so that the safety of the structure under the maximum deformation is ensured.
6. The method of claim 1, wherein when the step four is a one-step molding, the integrated molding further comprises voxel-level variable wall thickness materialization processing and gray scale exposure strategies: Carrying out non-uniform materialization treatment on the wavy structure by utilizing a gradient slicing technology; the voxel property of the wave crest region is set to be a first wall thickness and high crosslinking density, the voxel property of the wave trough region is set to be a second wall thickness and low crosslinking density, and the constraint relation of the first wall thickness to the second wall thickness is met, so that an elastic hinge is formed at the wave trough, and a rigid supporting structure is formed at the wave crest; applying high-intensity ultraviolet light exposure energy to the voxel position corresponding to the wave crest region, and applying lower-intensity ultraviolet light exposure energy to the voxel position corresponding to the wave trough region; And generating a staggered interlocking zipper type printing path by utilizing gradient slicing in the boundary transition area of the first wall thickness and the second wall thickness so as to enhance the mechanical binding force of a local interface.
7. An anisotropic force application unit of an invisible appliance, wherein the force application unit is arranged at a tooth-missing gap of the invisible appliance and comprises: The miniature rigid base structure is a non-closed curved beam structure which is positioned at the gingival end, is constructed to extend to the deep part of the gingival and has slightly upturned tail end, wherein the thickness of the non-closed curved beam structure is less than or equal to 0.15mm The cross section of the base structure is in a micro-hemming shape and is configured to improve the cross section moment of inertia through geometric optimization, so that deformation-resistant support is provided under a micro size and a rounded mucosa protecting surface is formed; The parameterized mechanical control panel is connected above the rigid base structure and consists of a wave structure formed by continuously alternating wave crests and wave troughs; wherein the mechanical control panel has anisotropic elastic modulus distribution, and is characterized in that the geometric trend angle of wave texture is regulated and controlled Wavelength of Amplitude of wave And/or local wall thickness distribution So that the stiffness of the force applying unit in the near-far middle direction Stiffness in the vertical direction The ratio is adjustable to achieve gap closure, development, or tooth torque control.
8. The anisotropic force applying unit of claim 7, wherein when the force applying unit is an additively manufactured variable wall thickness structure, the mechanical control panel has a wall thickness profile Exhibiting a periodic gradient change: Having a first wall thickness at the crest of the wave structure Having a second wall thickness at the trough And (2) and ; The thicker wave crest region forms an anti-deformation supporting structure and is used for maintaining the geometric stability of the wave shape; The wall thickness distribution satisfies a preset nonlinear mechanical response function to output a constant force value in an effective correction range.
9. The invisible appliance anisotropic force application unit of claim 7, wherein the force application unit is configured to have at least one of the following functional modes: A closed gap mode, wherein the wave texture is longitudinal and configured to provide a constant resilience force under tensile deformation; developing a gap mode, wherein the wave texture is transverse, the wave crest wall thickness is thickened, and the wave crest wall thickness is configured to serve as a compression-resistant strut to provide thrust under compression deformation; Torque control mode-the wave texture parameters of the buccal and lingual surfaces are asymmetric and configured to produce a moment of couple.
10. A bracket-free invisible appliance comprising an anisotropic force application unit according to any one of claims 7 to 9.

Description

Anisotropic stress application unit of invisible appliance and additive manufacturing method thereof Technical Field The invention belongs to the technical field of digital orthodontic medical appliance manufacturing, and particularly relates to an intelligent stress application unit with anisotropic mechanical response based on additive manufacturing or improved hot-pressing film technology for a bracket-free invisible appliance and a digital design and manufacturing method thereof. The invention is particularly suitable for handling tooth extraction cases, closing of gaps between dentitions at different distances, development of gaps between dentitions, and biomechanical control of complex tooth movements. Background With the development of digital oral technology, the bracket-free invisible correction technology has become the mainstream means of modern orthodontic treatment due to the advantages of beautiful appearance, comfort, removable wear, sanitation and the like, however, with the continuous expansion of invisible correction indications, the invisible correction technology faces serious biomechanical challenges and material limitations when treating complex cases, especially cases involving tooth extraction gaps such as first premolars or long-distance gaps. In the prior art, a simple plastic shell with smooth surface is usually designed on an appliance, commonly called denture cavitation, and the traditional design maintains the integrity of dentition visually, but has the following defects which are difficult to overcome in terms of mechanical property, clinical curative effect and wearing comfort: Conventional cavitation structures are usually thermoformed from homogeneous films, exhibit isotropic mechanical characteristics, the stiffness and elasticity of which are entirely dependent on the properties of the material itself and the film thickness, and when it is desired to close the tooth extraction gap, such structures often exhibit extreme characteristics of being too hard or too soft, if designed to be too hard, the appliance being difficult to wear and the initial appliance force being too great to produce, easily leading to derailment of the mouthpiece, if designed to be too soft, failing to produce a sustained effective return force to pull the teeth, and more seriously, conventional cavitation is passive, failing to actively push the gap away as a push spring in a fixed appliance, nor to provide a complex moment of couple to control root torque. The simple thin-wall cavitation structure has insufficient rigidity at a large-span tooth extraction gap, is extremely easy to collapse when being subjected to chewing and biting force in the vertical direction, so that the jaw teeth are elongated or the tooth socket is deformed, and when the appliance is subjected to traction force in the horizontal direction, the cavitation side walls are easy to distort and deform, so that adjacent teeth on two sides of the gap incline to the gap side, namely clinically common adjacent teeth lodging phenomenon is not expected integral translation, and the anchorage control and treatment effects are seriously influenced. The prior invisible appliance is mainly manufactured by adopting a hot-pressing film process, the process relies on a stretching covering model of a heated plastic film, the film is extremely difficult to form deep in gums and has the characteristics of complex rolling structures due to the stretching thinning effect of the film, and is easy to break or uneven in thickness, therefore, the traditional process cannot realize a miniaturized curled edge structure, a single-layer edge which is simply prolonged for increasing strength can become sharp like a blade after stretching, and the edge is extremely easy to cut oral mucosa to cause severe pain and ulcer for patients with shallower vestibular sulcus, particularly lower jaw or children, and in addition, the hot-pressing film process cannot realize point-to-point material attribute control such as local hardening or softening on the same appliance, so that the degree of freedom of mechanical design is limited. Most of the current gap designs are based on simple filling of geometric shapes, and lack of reverse design based on biomechanical targets, and although the application of digital twinning in additive manufacturing has been mentioned in the literature, the application of digital twinning in parameterization generation of complex mechanical structures of invisible appliances has not been specifically applied. In view of the foregoing, there is a need in clinic for an innovative structural design of an invisible appliance and a manufacturing method thereof, which can break through the limitation of the traditional hot-pressing film process, and perfectly combine engineering structural mechanics, an intelligent algorithm and an additive manufacturing technology to construct an intelligent stressing unit with extremely high adaptability, whic