A kind of invisible active expansion device for children with maxillary protrusion in dentition replacement period and its manufacturing method

Abstract

The present application relates to a kind of for replacing dentition period maxillary protrusion child invisible active expansion arch device, manufacturing method and its use method, belong to oral correction equipment technical field.The device includes invisible appliance mouthpiece and expansion arch hard palate plate, invisible appliance mouthpiece includes outer covering area and inner covering area, inner covering area is provided with support missing slot, expansion arch hard palate plate is inserted into support missing slot and the two sides of outer covering area are stretched out to realize expansion arch.Manufacturing method includes three-dimensional data acquisition, digital modeling, expansion arch module prefabrication, finite element simulation verification, split type additive manufacturing and post-processing precision calibration.Wearing method includes initial wearing assembly, routine wearing maintenance, recheck evaluation and ladder replacement and maintenance stage.The present application is realized by split type insertion structure to achieve the ladder precision regulation of expansion arch amount, and the buffer cavity is formed in front tooth area to form protective buffer layer, with bone expansion arch and front tooth injury protection function, suitable for replacing dentition period maxillary protrusion child.

Description

Technical Field

[0001] This invention relates to the field of oral orthodontic equipment technology, and in particular to an invisible removable arch expander for children with maxillary protrusion during the mixed dentition stage, and a method for manufacturing the arch expander. Background Technology

[0002] The mixed dentition period (6-12 years old) is a critical window for jawbone growth and development in children. Some children in this period exhibit labial protrusion of the maxillary central incisors, accompanied by insufficient development of the maxillary bone width. Without timely intervention, this will worsen crowding and protrusion, increasing the difficulty of subsequent orthodontic treatment in the permanent dentition. Furthermore, the protruding maxillary incisors lack protection during daily activities, making them prone to dental trauma.

[0003] Currently, commonly used orthodontic appliances in clinical practice include traditional fixed expanders and invisible expanders. Traditional fixed expanders are metal devices, which cause a strong foreign body sensation, have poor aesthetics, and exert a large expanding force that cannot be finely adjusted, easily leading to pain and tooth root resorption. Existing invisible expanders have the following drawbacks: 1. The integrated rigid structure applies continuous active orthodontic force to the anterior teeth, easily interfering with the eruption of lateral incisor tooth germs and the development of anterior tooth roots; 2. The expanding effect is concentrated on the crown, mainly causing buccal tilting of posterior teeth, with poor skeletal expanding effect; 3. The overall size is fixed after molding, and the expansion amount cannot be adjusted stepwise, requiring repeated remaking, resulting in high costs; 4. The palatal plate is mostly a flat structure, which cannot conform to the physiological morphology of the palatal vault, resulting in a single target point. In addition, existing children's dental appliances are only simple sports protection braces and do not have the function of expanding orthodontic treatment.

[0004] Therefore, there is an urgent need for an invisible removable arch expander that combines zero orthodontic force protection for anterior teeth, skeletal expansion, step-by-step adjustability, and conformity to the physiological morphology of the palatal vault, along with its corresponding usage method. Summary of the Invention

[0005] The purpose of this invention is to provide an invisible removable arch expander for children with maxillary protrusion during the mixed dentition stage and a method for manufacturing the same, so as to solve one or all of the technical problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: A first aspect of the present invention provides an invisible removable arch expander for children with maxillary protrusion during the mixed dentition stage, comprising: The invisible aligner includes an outer cover and an inner cover. The outer cover is U-shaped and covers the periphery of the teeth. The inner cover is located inside the outer cover and has a support notch. The hard palate expander is fitted with the support notch and can be inserted and fixed into the support notch. The hard palate expander is used to expand the two sides of the outer cover outward to achieve arch expansion. In this design, the side of the support notch closest to the opening area of ​​the outer cover is the inner side, and the side of the support notch furthest from the opening area of ​​the outer cover is the outer side.

[0007] According to one embodiment of the present invention, the support notch is arranged in a trapezoidal shape, and the inner width of the support notch is greater than the outer width of the support notch; the arch-expanding hard palate plate is arranged in a trapezoidal shape, and the inner width of the arch-expanding hard palate plate is greater than the outer width of the arch-expanding hard palate plate.

[0008] According to one embodiment of the present invention, the support notch is rectangular and the arch-expanding hard palate plate is rectangular.

[0009] According to one embodiment of the present invention, the support notch is arranged in an isosceles triangle, with the apex of the support notch facing outward; the arch-expanding hard palate plate is arranged in an isosceles triangle, with the apex of the arch-expanding hard palate plate facing outward.

[0010] According to one embodiment of the present invention, the outer side wall of the palatal expander is provided with a fitting portion, the inner side wall of the support notch is provided with a fitting groove, and the fitting portion is slidably inserted into the fitting groove.

[0011] According to one embodiment of the present invention, a buffer cavity is provided between the anterior tooth section of the outer covering and the upper anterior tooth.

[0012] According to one embodiment of the present invention, the palatal expander is a rigid structure integrally molded from medical polymer material, the palatal expander is conforming to the physiological curvature of the palatal dome, and the flexural modulus of the palatal expander is not less than 3.6 GPa.

[0013] A second aspect of the present invention provides a method for manufacturing a stealthy movable bow expander, comprising the following steps: S1: Clinical individualized 3D data acquisition and standardized preprocessing: The maxillary dentition, hard palate and alveolar mucosa of the child are scanned using oral 3D scanning equipment to obtain 3D dental data and perform noise reduction, simplification and smoothing to generate a standardized basic dental model; S2: Digital parametric modeling of the appliance substrate: A digital model of the invisible aligner is constructed on the basic dental model. The invisible aligner includes an outer cover and an inner cover. The inner cover is provided with a support notch, and a buffer cavity is reserved in the anterior tooth section of the outer cover. S3: Prefabrication and customization of serialized detachable palatal expansion modules: Prefabricate multiple digital models of palatal expansion plates with different lateral widths, with the lateral width increment between adjacent specifications of palatal expansion plates being 0.5 to 1.0 mm; S4: Full-system anterior tooth zero-stress simulation verification: Assemble the digital model of the invisible aligner with the digital model of the palate expansion plate, and verify through finite element mechanical simulation that the maximum stress value of the anterior tooth segment does not exceed the preset stress threshold, 1MPa≥preset stress threshold>0MPa; S5: Split additive manufacturing adaptable to multiple materials: separately manufacture the invisible aligner braces and multiple palatal expansion plates of different sizes; S6: Post-processing and precision calibration: The invisible aligner and the palatal expansion plate are cleaned, the support is removed, and a second curing process is performed. The assembly structure is then calibrated for precision.

[0014] According to an embodiment of the present invention, in step S5, the invisible aligner is manufactured using a 3D printing process, wherein the 3D printing process employs selective laser sintering or photopolymerization.

[0015] A third aspect of the present invention provides a method for wearing and using an invisible movable bow expander, comprising the following steps: Y1: Initial fitting: The clear aligner is placed on the child's maxillary dentition, ensuring that the outer cover of the clear aligner covers the entire maxillary dentition, with the posterior segment closely fitting the crowns of the posterior teeth and the anterior segment maintaining a buffer space between the anterior teeth and the upper anterior teeth; the palatal expansion plate is placed along the palatal direction into the support notch of the inner cover and secured; the fit between the palatal expansion plate and the palatal vault mucosa and the retention stability of the clear aligner are checked to confirm that there is no local mucosal compression; Y2: Daily wear and maintenance, requiring a total daily wear time of no less than 20 hours for the invisible aligners and the palatal expansion plate; Y3: Follow-up assessment, measuring the width of the dental arch on the palatal side of the maxillary canine and first permanent molar to quantitatively assess the progress of arch expansion, while checking the fit of the invisible aligner, the stability of the hard palatal plate of the arch expansion, and the health of the palatal mucosa and periodontium. Y4: Step replacement. Once the maxillary width reaches the treatment target of the current size palatal expansion plate, first remove the current palatal expansion plate and clean the support slot. Then, select the next size palatal expansion plate with a lateral width increased by 0.5 to 1.0 mm, insert it into the support slot, and snap it in place. If the fit of the clear aligner decreases due to changes in the dentition during the mixed dentition period, the clear aligner will be partially re-lined or remade, and the original series of palatal expansion plates will continue to be used. Y5: Retention phase. After active arch expansion reaches the treatment endpoint, stop replacing the gradient arch expansion hard palate plate and replace it with a stable arch expansion hard palate plate that matches the final width, or directly use the aforementioned clear aligner as a retainer. The wearing time gradually decreases, and the total retention period is not less than 12 months.

[0016] Beneficial effects This invention has at least one of the following technical effects: Firstly, this invention employs a structure in which the supporting notch and the expanding hard palate plate fit together and are inserted into each other. After the expanding hard palate plate is inserted into the supporting notch, it expands the two sides of the outer coverage area outward to achieve the expansion function. This split insertion structure means that the expansion amount of the orthodontic appliance is no longer limited by the fixed size of the integrated molding. Clinicians can replace the expanding hard palate plate of different widths at any time according to the actual changes in the width of the child's maxilla, so as to achieve precise and step-by-step adjustment of the expansion amount. There is no need to replace the entire orthodontic appliance, which greatly reduces the cost of treatment and improves the efficiency of clinical diagnosis and treatment.

[0017] Secondly, this invention, by setting up a double-layer structure of an outer and inner covering area, and setting a support notch in the inner covering area as the assembly site for the palatal expansion plate, realizes a directional transmission path of the expansion force from the palatal expansion plate through the inner covering area and the support notch to both sides of the outer covering area. The expansion force can effectively act on the palatal midline area, open the palatal midline, stimulate the transverse growth of the maxilla, achieve skeletal expansion, and increase the bone volume of the maxilla from the root. It overcomes the dental expansion defect of the prior art, where the expansion force is only concentrated on the crown of the tooth, causing buccal tilt of the posterior teeth. The orthodontic effect is stable and the relapse rate is low.

[0018] Thirdly, in this invention, the outer and inner coverage areas of the invisible aligner form an integrated flexible base. A buffer cavity is provided between the anterior tooth section of the outer coverage area and the upper anterior teeth to form a flexible protective buffer layer. When subjected to external force, the buffer cavity preferentially absorbs the impact energy, and the remaining impact force is transmitted posteriorly through the outer coverage area to the hard palate plate for dispersion and dissipation, thus preventing the upper anterior teeth from being directly subjected to force and thus from fracture or dislocation. This structure provides reliable passive protection for protruding upper anterior teeth without outputting any active orthodontic force, thus taking into account both orthodontic and protective functions. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A diagram illustrating the usage status of the stealthy mobile bow expander. Figure 1 ; Figure 2 A diagram illustrating the usage status of the stealthy mobile bow expander. Figure 2 ; Figure 3 A diagram illustrating the usage status of the stealthy mobile bow expander. Figure 3 ; Figure 4 This is a structural diagram of the invisible aligner in an invisible removable arch expander system. Figure 5 A schematic diagram of one embodiment of the hard palate expander; Figure 6 A schematic diagram of a clear aligner with an expanded palatal plate installed. Figure 7 This is a schematic diagram of the structure of invisible aligners without the hard palate expansion plate installed. Figure 8 A schematic diagram showing the setup of the buffer chamber in the concealed movable bow expander; Figure 9 This is a schematic diagram illustrating the changes in the mid-palatal suture of the maxilla during treatment with an invisible movable arch expander.

[0021] Explanation of reference numerals in the attached figures: 1. Invisible aligner; 11. Outer overlay; 12. Inner overlay; 13. Support notch; 131. Fitting groove; 14. Buffer cavity; 2. Palatal expansion plate; 21. Fitting. Detailed Implementation

[0022] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and to exemplify the principles of the present invention, and are not configured to limit the present invention. In addition, the structural components in the drawings are not necessarily drawn to scale. For example, the dimensions of some structural components or regions in the drawings may be enlarged for other structural components or regions to aid in the understanding of the embodiments of the present invention.

[0023] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of the embodiments of the present invention. In the description of the present invention, it should be noted that, unless otherwise stated, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0024] Furthermore, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a structure or component that includes a list of elements includes not only those elements but also other structural elements that are not expressly listed or inherent to the structure or component. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the article or apparatus that includes the element.

[0025] Spatial relation terms such as "below," "under," "under," "low," "above," "on," and "high" are used for descriptive convenience to explain the positioning of one element relative to a second element, indicating that these terms are intended to cover different orientations of the device, in addition to those different from those shown in the figure. Furthermore, phrases such as "one element on / below another element" can indicate that two elements are in direct contact, or that there are other elements between the two elements. In addition, terms such as "first" and "second" are also used to describe individual elements, areas, parts, etc., without specifically indicating order or sequence, and should not be considered restrictive. Similar terms are used throughout the description to represent similar elements.

[0026] It will be apparent to those skilled in the art that the present invention can be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention.

[0027] In the following embodiments, there may be descriptions such as "this device". Those skilled in the art should understand that "this device" refers to the invisible removable arch expander for children with maxillary protrusion during the mixed dentition period, its manufacturing method and its usage method provided by the present invention.

[0028] The following is in conjunction with the appendix Figure 1-9 As shown, where Figure 1 A diagram illustrating the usage status of the stealthy mobile bow expander. Figure 1 , Figure 2 A diagram illustrating the usage status of the stealthy mobile bow expander. Figure 2 , Figure 3 A diagram illustrating the usage status of the stealthy mobile bow expander. Figure 3 , Figure 4 This is a structural diagram of the invisible aligner in an invisible removable arch expander system. Figure 5 This is a schematic diagram of one embodiment of the hard palate expander. Figure 6 A schematic diagram showing the structure of an invisible aligner with an expanded palate plate in place. Figure 7 This is a schematic diagram of the structure of invisible aligners without the hard palate expander installed. Figure 8 This is a schematic diagram showing the configuration of the buffer chamber in a concealed movable bow expander. Figure 9This is a schematic diagram illustrating the changes in the mid-palatal suture of the maxilla during treatment with an invisible movable arch expander.

[0029] This embodiment provides an invisible removable palate expander for children with maxillary protrusion during the mixed dentition stage. It includes an invisible aligner 1 and a palate expander 2. The invisible aligner 1 is made of medical-grade polymer material and is integrally molded using 3D printing. It has a U-shaped design and is used to cover the entire maxillary dentition of the child. The invisible aligner 1 includes an outer covering 11 and an inner covering 12. The outer covering 11 is U-shaped and covers the circumference of all maxillary teeth, including the anterior and posterior segments. The anterior segment of the outer covering 11 is connected to the maxillary... A buffer cavity 14 is reserved between the tooth surfaces of the central incisors and primary anterior teeth. The width of the buffer cavity 14 is less than 0.2 mm. It does not output any active orthodontic force, squeezing force or displacement force, but only forms a flexible protective buffer layer to buffer the impact force, protect the tooth body and isolate the impact when subjected to external force collision. The posterior tooth section of the outer cover 11 fits tightly with the crown of the posterior tooth to provide stable retention. The inner cover 12 is set inside the outer cover 11, corresponding to the position of the maxilla. The inner cover 12 is provided with a support notch 13.

[0030] The palatal expansion plate 2 is integrally printed using medical-grade high-strength polymer material, spanning the entire hard palate region of the maxilla. It conforms to the three-dimensional physiological curvature of the natural palatal dome, unlike traditional flat plate structures. The curvature height is adapted to the shape of the palatal dome. The palatal expansion plate 2 fits and is inserted into the support notch 13. After wearing the palatal expansion plate 2, it can continuously apply expansion force to the bilateral palatal maxilla and alveolar bone, and transmit the force to the posterior teeth area with the help of the invisible aligner 1. This applies a gentle and stable expansion force to the palatal midline, thereby expanding the palatal midline and stimulating the transverse growth of the maxilla to achieve skeletal expansion. At the same time, it can ensure that the palatal expansion plate 2 fits snugly against the maxilla after being fitted on the invisible aligner 1, and will not fall off during use.

[0031] In some embodiments, a snap-fit ​​or / or slot structure is provided between the hard palate expander 2 and the support notch 13, and after the hard palate expander 2 is assembled, the snap-fit ​​on it is fixed relative to the slot on the support notch 13.

[0032] Among them, the side of the support notch 13 closest to the opening area of ​​the outer cover 11 is the inner side, and the side of the support notch 13 furthest from the opening area of ​​the outer cover 11 is the outer side.

[0033] In some embodiments, the lateral width of the palatal expansion plate 2 is determined based on the child's initial maxillary width. This scheme is equipped with a series of palatal expansion plates 2 with different specifications. The lateral width increment between adjacent specifications of palatal expansion plates 2 is 0.5 to 1.0 mm, forming a standardized micro-expansion gradient. The lateral width increment is selected according to the child's age and jawbone development rate: 1.0 mm increment is selected for older children or children with faster development, and 0.5 mm increment is selected for younger children or children with weak tolerance. During clinical follow-up visits, the old palatal expansion plate 2 can be removed and replaced with a new palatal expansion plate 2 with a larger width, based on the child's jawbone development progress and the expansion of the palatal midline, to achieve monthly micro-expansion, step-by-step personalized skeletal expansion.

[0034] In some embodiments, the palatal expansion plate 2 is integrally printed using polyetheretherketone (PEEK) material. PEEK material has excellent mechanical properties, wear resistance, and biocompatibility, with a flexural modulus of over 3.6 GPa. It can provide continuous and stable expansion force for the mid-palatal suture and is not prone to creep deformation with long-term use, ensuring stable output of expansion force throughout the entire orthodontic cycle.

[0035] The palatal expander 2 in this solution can be configured with different shapes according to the actual processing conditions and the different oral structures of the patients, including but not limited to the following implementation methods: Implementation method 1 of the palatal expander 2: The support notch 13 is set in a trapezoidal shape, and the inner width of the support notch 13 is greater than the outer width of the support notch 13. The palatal expander 2 is set in a trapezoidal shape, and the inner width of the palatal expander 2 is greater than the outer width of the palatal expander 2. The trapezoidal fitting structure is adopted. During the process of inserting the palatal expander 2 into the support notch 13 from the inside to the outside, the trapezoidal slope can play a guiding role, which makes it easy for the palatal expander 2 to be accurately positioned. At the same time, the trapezoidal structure makes the palatal expander 2 form a wedge-tight fit with the support notch 13 after it is in place, which enhances the assembly stability and prevents the palatal expander 2 from shifting or loosening during use. Implementation method 2 of the palatal expander plate 2: The support notch 13 is set in an isosceles triangle with the apex of the support notch 13 facing outwards. The palatal expander plate 2 is also set in an isosceles triangle with the apex of the palatal expander plate 2 facing outwards. During the process of inserting the palatal expander plate 2 into the support notch 13 from the inside to the outside, the guiding effect of the triangular inclined surface is more significant, which can further improve the convenience and accuracy of assembly. At the same time, the isosceles triangle structure has good symmetry, and the force transmission is more uniform, which is conducive to the stable output of the expansion force. Implementation method 3 of the arch-expanding hard palate plate 2: The support notch 13 is rectangular. The arch-expanding hard palate plate 2 adopts a rectangular mating structure. The rectangular arch-expanding hard palate plate 2 and the support notch 13 are simpler to process and have lower cost, while providing good support.

[0036] In some embodiments, the outer side wall of the palatal expander 2 is provided with a fitting portion 21, and the inner side wall of the support notch 13 is provided with a fitting groove 131. The positions of the fitting portion 21 and the fitting groove 131 correspond to each other, and the cross-sectional shape of the fitting portion 21 matches the cross-sectional shape of the fitting groove 131. The fitting portion 21 on the palatal expander 2 is slidably inserted into the fitting groove 131 along the longitudinal direction of the support notch 13, thereby realizing the rapid installation of the palatal expander 2. By setting the sliding fit structure between the fitting portion 21 and the fitting groove 131, on the one hand, the insertion direction of the palatal expander 2 is guided and limited to ensure that the palatal expander 2 is accurately positioned according to the preset trajectory; on the other hand, after the palatal expander 2 is in place, the fit between the fitting portion 21 and the fitting groove 131 can provide additional anti-dislocation force and enhance the assembly stability of the palatal expander 2.

[0037] In some embodiments, the palatal expansion plate 2 completely conforms to the three-dimensional physiological surface of the palatal vault of the child, and extends vertically to cover the entire length of the palatal alveolar process of the maxillary posterior teeth. After assembly, the palatal expansion plate 2 can simultaneously conform to the palatal tooth surface of the posterior teeth, the palatal alveolar bone surface, and the palatal midline region, with a wide force coverage, uniform force distribution, and high bone remodeling efficiency.

[0038] In some embodiments, a buffer cavity 14 is provided between the anterior tooth section of the outer covering 11 and the upper anterior teeth. In the daily activities of the child, if the upper anterior teeth are hit by external force, the buffer cavity 14 of the anterior tooth section of the outer covering 11 forms a first-level buffer, preferentially absorbing part of the impact energy. Subsequently, the outer covering 11 drives the anterior tooth area to move slightly backward, transmitting the remaining impact force backward along the palatal base, and finally dissipating it by the high-rigidity arch-expanding hard palate plate 2, thus avoiding direct force on the upper anterior teeth and causing dental trauma such as fracture or dislocation.

[0039] This embodiment also provides a method for manufacturing an invisible removable arch expander for children with maxillary protrusion during the mixed dentition period, including the following steps: Step S1: Clinical individualized 3D data acquisition and standardized preprocessing; A three-dimensional oral scanning device was used to perform a full-range scan of the maxillary dentition, hard palate, and alveolar mucosa of children in the mixed dentition stage. The scanning range covered the distal part of the bilateral first permanent molars, the complete hard palate anatomical region, the entire anterior dentition region, and the mucosal region corresponding to the unerupted teeth, obtaining high-precision original dental point cloud data. The original data was then denoised, simplified, and smoothed, and redundant scan points and artifact data were removed, while retaining the real tooth morphology, hard palate bone contour, and morphological information of soft tissues such as the maxillary hard palate mucosa and gingiva, generating a standardized basic dental model.

[0040] Step S2: Digital parametric modeling of the orthodontic appliance substrate; A digital model of the invisible aligner 1 was constructed on the basic dental model. The invisible aligner 1 includes an outer cover area and an inner cover area. The inner cover area is equipped with a support notch 13. When modeling the anterior tooth protective buffer structure, a buffer cavity 14 was reserved on the labial surface of the maxillary central incisor. The buffer cavity 14 has a width of 0.2 mm and adopts a passive fit design without pre-tightening or compression to ensure that no force is applied to the anterior teeth during the modeling stage. When modeling the posterior tooth retention base, a full-coverage retention base with a thickness of 0.8 mm was generated for the maxillary first premolar and first permanent molar. It is precisely fitted to the tooth undercut to achieve active retention. During the modeling process, the anterior tooth protective structure and the arch expansion structure were forcibly set to have no physical connection, no coplanarity, and no stress transmission path, so as to achieve complete mechanical isolation of the two functional systems from the design source.

[0041] Step S3: Prefabrication and customized production of serialized detachable bow expander modules; A series of prefabricated universal palate expansion modules are developed, forming a tiered specification module library. The effective lateral expansion width increment of adjacent specification palate expansion plates 2 is 0.5-1.0mm. The modules adopt a closed frame structure, with reserved standardized insertion ends, and are tolerance-matched with the support notch 13 in the inner coverage area of ​​the invisible aligner 1. Mechanical simulation calibration is performed on each specification module to ensure that the expansion force is stable within the pediatric fit range of 50-80g, with a force deviation of no more than ±10g, ensuring safe and controllable clinical expansion.

[0042] Step S4: Full-system anterior tooth zero-stress simulation verification; The digital model of the completed invisible aligner 1 was virtually assembled with the matching digital model of the palatal expansion plate 2. Full-condition stress verification was performed using finite element method (FEM) simulation software. The verification criteria were: the stress values ​​in the maxillary central and lateral incisor regions did not exceed the preset stress threshold; the stress magnitude was sufficient to ensure that wearing the invisible aligner 1 alone did not cause tooth deformation or displacement; furthermore, 1 MPa ≥ preset stress threshold > 0 MPa. There is no stress transmission, no compressive stress, and no tensile stress, achieving absolute zero force application. If the verification fails, return to step S2 to remodel.

[0043] Step S5: Adapting multi-material modular additive manufacturing; Material selection: Medical polymer materials that meet the requirements of oral biosafety standards are selected. The material properties meet the following requirements: flexural modulus not less than 3.6GPa, Shore hardness not less than D80, and tensile strength not less than 80MPa. Process matching: The corresponding 3D printing process is adapted according to the selected material. Selective laser sintering or photopolymerization can be used to ensure structural accuracy and mechanical properties. Separate printing: The invisible aligner 1 and the complete set of gradient specification palatal expansion plates 2 are printed separately to ensure the independence of disassembly and assembly and the independence of deformation of each component.

[0044] Step S6: Post-processing and accuracy calibration; After printing, the clear aligner 1 and the palate expander 2 are cleaned, the support is removed, and a second curing process is performed. If PEEK material is used, annealing is performed to eliminate internal stress and ensure structural dimensional stability. The fit between the support notch 13 and the end of the palate expander 2 is precisely calibrated, and the assembly tolerance is controlled within ±0.02mm to ensure that the palate expander 2 can be easily installed and removed without loosening or displacement. All structural edges are polished to remove burrs and sharp edges to ensure accurate mechanical expression and wearing comfort. After sterilization, the clear aligner 1 and the complete set of graded palate expanders 2 are packaged together to form a complete treatment cycle kit for clinical use.

[0045] As a preferred option, selective laser sintering (SLS) is used for printing. SLS uses a laser as a heat source to selectively sinter powdered medical polymer materials, stacking them layer by layer to form a three-dimensional solid. This process does not require a support structure and is suitable for manufacturing orthodontic components with complex internal structures and fine snap-fit ​​features. The molded parts also have excellent mechanical properties and good isotropy.

[0046] As another preferred option, a photopolymerization process is used for printing. The photopolymerization process uses ultraviolet light as a light source to selectively cure liquid photosensitive resin, which is then deposited layer by layer to form a three-dimensional solid. This process has high molding precision and good surface quality, and is suitable for manufacturing orthodontic components with high requirements for surface smoothness and dimensional accuracy.

[0047] The transverse width of the first-size palatal expansion plate 2 is determined based on the child's initial maxillary width. The overall gradient level is calculated and set according to the target total expansion amount. The target total expansion amount is determined by the difference between the maxillary basal bone width measured by preoperative CBCT images and the ideal width. The transverse width increment of adjacent-size palatal expansion plates 2 is 0.5 to 1.0 mm.

[0048] Specifically, for children aged 6-8 years with slower jawbone development and lower tolerance, a 0.5mm increment is chosen to adapt to the physiological laws of jawbone growth and remodeling with a gentler expansion rhythm; for children aged 9-12 years with faster development and better tolerance, a 1.0mm increment is chosen to improve orthodontic efficiency while ensuring safety.

[0049] The total number of serialized palatal expanders 2 is determined by dividing the target total expansion amount by the single increment. For example, if the target total expansion amount is 5mm and the single increment is 0.5mm, then 10 sizes of palatal expanders 2 are required; if the target total expansion amount is 5mm and the single increment is 1.0mm, then 5 sizes of palatal expanders 2 are required.

[0050] This embodiment further provides a method for wearing an invisible removable arch expander for children with maxillary protrusion during the mixed dentition period, including the following steps: Step Y1: Initial Fitting The invisible aligner 1 is placed on the child's maxillary dentition, ensuring that the outer coverage area of ​​the invisible aligner 1 covers the entire maxillary dentition. In the specific operation, the anterior segment of the outer coverage area is initially aligned with the position of the upper anterior teeth. Then, it is gradually pressed and fitted along the dental arch towards the posterior teeth on both sides until the posterior teeth completely cover the crowns and the invisible aligner 1 is not tilted. The palatal expansion plate 2 is then smoothly placed into the support notch 13 of the inner coverage area along the palatal midline and from the palatal side to the anterior teeth side. The fitting structure of the support notch 13 is precisely anchored, and pressure is applied evenly from the midline towards the palatal sides on both sides until the fitting structure is completely engaged.

[0051] Step Y2: Daily Wearing and Maintenance The total daily wearing time of the invisible aligner 1 and the palate expander 2 should not be less than 20 hours, and they should only be temporarily removed when brushing teeth.

[0052] Step Y3: Follow-up visit and assessment. Follow-up visits are scheduled every 4-6 weeks for a multi-dimensional assessment. Intraoral examinations include assessing the fit and retention of the clear aligner 1, the stability of the palatal expansion plate 2, the occlusal relationship of the posterior teeth, and the health of the palatal mucosa and periodontium. Width measurements include fixed-point measurements of the palatal arch width of the maxillary canines and first permanent molars to quantitatively assess the progress of arch expansion. Imaging assessments include CBCT scans every six months or more to confirm the expansion status of the palatal midline and the quality of bone remodeling, and to screen for adverse reactions such as posterior buccal tipping and root resorption.

[0053] Step Y4: Step Replacement Once the maxillary width reaches the corrective target of the current size palatal expansion plate 2, the palatal expansion plate 2 is replaced. First, the current palatal expansion plate 2 is removed, and the support notch 13 and mating structure in the covered area of ​​the clear aligner 1 are cleaned. Any wear or damage is checked. Based on the child's jawbone development rate and tolerance to palatal suture expansion, the next size palatal expansion plate 2 with a lateral width increase of 0.5 to 1.0 mm is selected. For older children with faster development and good tolerance, a 1.0 mm increment can be selected; for younger children with weaker tolerance, a 0.5 mm increment can be selected. The new palatal expansion plate 2 is then attached and fixed according to the standard assembly procedure. The fit, retention stability, and mucosal compression are checked again.

[0054] Step Y5: End of Treatment and Retention The determination of the endpoint of orthodontic treatment requires the following conditions to be met simultaneously: the width of the maxillary basal bone reaches the preset orthodontic target, the posterior crossbite is completely eliminated, and the occlusal relationship is stable; CBCT images show continuous new bone formation in the palatal midline area and good bone remodeling; there are no obvious complications such as posterior buccal tipping or root resorption, and the anterior tooth protrusion has not worsened abnormally.

[0055] Follow-up visits were conducted every 6–12 months to observe the subsequent development of the maxilla, the alignment of the teeth, and the long-term stability of anterior occlusion, and to assess the long-term efficacy of skeletal expansion and the clinical benefits of anterior tooth protection.

[0056] It should be understood that the above-described embodiments or examples of the present invention can be combined with each other and have corresponding technical effects.

[0057] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A removable, invisible arch expander for children with maxillary protrusion during the mixed dentition stage, characterized in that, include: The invisible aligner (1) includes an outer cover (11) and an inner cover (12). The outer cover (11) is U-shaped and is used to cover the periphery of the teeth. The inner cover (12) is located inside the outer cover (11) and has a support notch (13). The hard palate expander (2) fits into the support notch (13). The hard palate expander (2) can be inserted and fixed into the support notch (13). The hard palate expander (2) is used to expand the two sides of the outer cover (11) outward to achieve the expansion. Among them, the side of the support notch (13) closest to the opening area of ​​the outer cover (11) is the inner side, and the side of the support notch (13) furthest from the opening area of ​​the outer cover (11) is the outer side.

2. The invisible removable arch expander for children with maxillary protrusion during the mixed dentition period as described in claim 1, characterized in that, The support notch (13) is arranged in a trapezoidal shape, and the inner width of the support notch (13) is greater than the outer width of the support notch (13); the arch-expanding hard palate plate (2) is arranged in a trapezoidal shape, and the inner width of the arch-expanding hard palate plate (2) is greater than the outer width of the arch-expanding hard palate plate (2).

3. The invisible removable arch expander for children with maxillary protrusion during the mixed dentition period as described in claim 1, characterized in that, The support notch (13) is rectangular, and the arch-expanding hard palate plate (2) is rectangular.

4. The invisible removable arch expander for children with maxillary protrusion during the mixed dentition period as described in claim 1, characterized in that, The support notch (13) is arranged in an isosceles triangle, with the apex of the support notch (13) facing outward; the arch-expanding hard palate plate (2) is arranged in an isosceles triangle, with the apex of the arch-expanding hard palate plate (2) facing outward.

5. The invisible removable arch expander for children with maxillary protrusion during the mixed dentition period according to any one of claims 1 to 4, characterized in that, The outer side wall of the expanding hard palate plate (2) is provided with a fitting part (21), and the inner side wall of the support notch (13) is provided with a fitting groove (131). The fitting part (21) is slidably inserted into the fitting groove (131).

6. The invisible removable arch expander for children with maxillary protrusion during the mixed dentition period according to any one of claims 1 to 4, characterized in that, A buffer cavity (14) is provided between the anterior tooth section of the outer covering part (11) and the upper anterior tooth.

7. The invisible removable arch expander for children with maxillary protrusion during the mixed dentition period according to any one of claims 1 to 4, characterized in that, The palatal expander (2) is a rigid structure integrally formed from medical polymer material. The palatal expander (2) is set to fit the physiological curvature of the palatal dome. The bending modulus of the palatal expander (2) is not less than 3.6 GPa.

8. A method for manufacturing the stealthy movable bow expander according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Clinical individualized 3D data acquisition and standardized preprocessing: The maxillary dentition, hard palate and alveolar mucosa of the child are scanned using oral 3D scanning equipment to obtain 3D dental data and perform noise reduction, simplification and smoothing to generate a standardized basic dental model; S2: Digital parametric modeling of the appliance base: A digital model of the invisible aligner (1) is constructed on the basic dental model. The invisible aligner (1) includes an outer cover (11) and an inner cover (12). The inner cover (12) is provided with a support notch (13), and a buffer cavity (14) is reserved in the anterior tooth section of the outer cover (11). S3: Prefabrication and customized generation of serialized detachable palatal expansion modules: Prefabricate multiple digital models of palatal expansion plates (2) with different lateral widths, with the lateral width increment of adjacent palatal expansion plates (2) being 0.5 to 1.0 mm; S4: Full system anterior tooth zero stress simulation verification: The digital model of the invisible aligner (1) is assembled with the digital model of the palate expansion plate (2), and the maximum stress value of the anterior tooth segment is verified by finite element mechanical simulation to not exceed the preset stress threshold. S5: Adaptable multi-material split additive manufacturing: manufacture the invisible aligner (1) and multiple palatal expansion plates (2) of different specifications separately. S6: Post-processing and precision calibration: The invisible aligner (1) and the palatal expansion plate (2) are cleaned, the support is removed, and secondary curing is performed, and the assembly structure is precision calibrated.

9. The manufacturing method according to claim 8, characterized in that, In step S5, the invisible aligner is manufactured using 3D printing technology, which employs selective laser sintering or photopolymerization.

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