An orthodontic appliance for closing a tooth extraction space and a method of manufacturing the same

Abstract

The application discloses an orthodontic appliance for closing tooth extraction gap, comprising front tooth treatment part, back tooth wrapping part and gap closing part, the front tooth treatment part wraps the front tooth as a whole, the back tooth wrapping part wraps the back tooth individually, the gap closing part comprises force applying part and retaining part, the force applying part comprises connecting body and retaining part, the connecting body spans the gap between the front tooth treatment part and the back tooth wrapping part and / or the gap between adjacent back tooth wrapping parts, the retaining part is arranged on the surface of the front tooth treatment part or the back tooth wrapping part, and the connecting body is retained through the retaining part. The manufacturing method of the orthodontic appliance is also disclosed. The application can efficiently close tooth extraction gap.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more particularly to invisible aligners for dental orthodontics. Background Technology

[0002] Orthodontic treatment, which involves applying corrective forces to move teeth, is the primary method for correcting malocclusion. For cases where there is a severe lack of space in the dental arch due to crowding, protrusion (such as buck teeth), tooth extraction is often necessary to create the required orthodontic space, thereby achieving tooth alignment and improving facial profile and occlusal function. In East Asian populations, the proportion of such extraction-based orthodontic treatments is as high as 60%-70%. Therefore, how to efficiently and accurately close and manage extraction spaces remains a key focus and challenge in orthodontic clinical research.

[0003] Currently, traditional fixed metal orthodontic techniques are mature and the mainstream method for handling complex tooth extraction cases. However, in recent years, invisible aligners have become increasingly popular with doctors and patients due to their aesthetic, comfort, and hygiene advantages. However, applying invisible aligners to tooth extraction cases still faces significant challenges, mainly in the following two aspects:

[0004] (1) Limitations of material mechanical properties: The polymer elastic materials used in invisible aligners have relatively low mechanical strength and are prone to creep and stress relaxation under continuous stress. This leads to a rapid decay of the orthodontic force, making it difficult to achieve large-scale and precise tooth movement. Especially when performing long-distance overall movement (such as closing extraction gaps), problems such as uncontrolled tooth movement or low efficiency are likely to occur.

[0005] (2) Constraints of traditional manufacturing processes: The current mainstream manufacturing process for invisible aligners is vacuum thermoforming. This process requires first 3D printing a digitally designed dental model, and then adsorbing a heated and softened polymer film onto the model surface to form the aligner. Due to this process, the aligner structure must be simple and cannot have obvious undercuts, otherwise it will be difficult to remove it from the model. Therefore, it is difficult to integrate complex active force application or control structures, which limits its ability to control tooth movement, especially root movement.

[0006] With advancements in additive manufacturing (3D printing) technology, direct 3D printing of invisible aligners has become possible. This technology breaks free from the constraints of thermoforming on geometry, providing ample room for structural innovation in aligners and enabling the compensation of material mechanical defects through refined design. Based on this, this invention aims to leverage the technological advantages of 3D printing to propose a novel aligner structure to address the problems of low efficiency and poor controllability in closing extraction gaps in existing invisible aligner technologies. Summary of the Invention

[0007] To overcome the above-mentioned shortcomings, the present invention aims to provide an orthodontic appliance for closing tooth extraction gaps, which can efficiently close tooth extraction gaps, and also provides a method for manufacturing such an orthodontic appliance.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An orthodontic appliance for closing extraction gaps includes an anterior orthodontic unit, a posterior enclosing unit, and a gap-closing unit. The anterior orthodontic unit completely encloses the anterior teeth, and the posterior enclosing unit encloses each posterior tooth individually. The gap-closing unit includes a force-applying component and a retention component. The force-applying component includes a connector and a retention component. The connector spans the gap between the anterior orthodontic unit and the posterior enclosing unit and / or the gap between adjacent posterior enclosing units. The retention component is disposed on the surface of the anterior orthodontic unit or the posterior enclosing unit, and the connector is retained by the retention component.

[0010] Preferably, gap closing components are provided on both the tongue side and the lip side.

[0011] Preferably, the retaining component is a clamping component, and the connecting body is strip-shaped, with the retaining component clamping the connecting body.

[0012] Furthermore, the connecting body is provided with a vertically bent portion and / or a horizontally bent portion.

[0013] Preferably, the anterior orthodontic unit covers the central incisor, lateral incisor, and canine.

[0014] This invention also discloses a method for manufacturing such an orthodontic appliance, comprising the following steps:

[0015] S1. Obtain a digital model of the patient's dentition and complete tooth segmentation and final occlusion design;

[0016] S2. Plan the step-by-step movement path from the initial dentition to the terminal dentition, and design the attachment morphology;

[0017] S3. Perform mechanical compensation design for the step-by-step movement target position, wherein the mechanical compensation design includes overcorrection of the root movement direction;

[0018] S4. Based on the compensated digital model, construct the anterior orthodontic area and the posterior encapsulation area respectively;

[0019] S5. Parametrically construct the gap closing part. By setting the morphological parameters of the connector, a three-dimensional structure with predetermined mechanical properties is generated.

[0020] S6. The orthodontic appliance is manufactured in an integrated manner using additive manufacturing technology.

[0021] Furthermore, step S5 also includes:

[0022] The connector located between the canine and the premolar is configured as the main force application zone across the extraction space to control the retraction of the anterior teeth and the loss of the anchorage of the posterior teeth.

[0023] The connector located between the premolar and molar is configured as a key area for controlling the stability and movement of the posterior anchorage unit;

[0024] The connectors located between molars are configured as a stable zone to maintain the shape and width of the posterior segment of the dental arch.

[0025] Preferably, in step S5, the morphological parameters of the connector are designed as follows:

[0026] Adjust the vertical thickness of the connector to meet the stiffness of the connector in the vertical direction, adjust the vertical curvature of the connector to meet the corrective force value of the connector in the vertical direction, and adjust the vertical crest height of the connector to meet the elastic force range of the connector in the vertical direction.

[0027] Adjust the horizontal thickness of the connector to meet the horizontal stiffness of the connector, adjust the horizontal curvature of the connector to meet the horizontal corrective force value of the connector, and adjust the horizontal crest height of the connector to meet the horizontal elastic force range of the connector.

[0028] Preferably, the morphological parameters of the connecting bodies in the main force application zone, the critical zone, and the stable zone are designed independently.

[0029] Preferably, the additive manufacturing technology is photopolymer 3D printing, and the material used is medical-grade photosensitive resin.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. Achieves precise and controllable adjustment of orthodontic force: This invention creatively designs a parameterized and adjustable force-applying connector in the gap-closing section. By precisely adjusting key parameters such as its vertical thickness (a), number of curves (n), peak height (h), and horizontal thickness (b), number of curves (m), and peak width (w), it can finely control the magnitude, stiffness, and effective range of the orthodontic force in three dimensions (vertical and horizontal) like "adjusting a spring." This solves the core problem of traditional invisible aligners, which suffer from rapid force decay and difficulty in maintaining effective force values ​​due to material stress relaxation, achieving precise biomechanical control over tooth movement, especially long-distance overall movement.

[0032] 2. Significantly improved anchorage control and treatment efficiency: The overall wrapping design of the anterior teeth ensures coordinated movement of the anterior teeth during retraction, preventing uncontrolled tilting of individual teeth. The independent design of the posterior teeth wrapping provides a stable and reliable anchorage unit for gap closure and enables independent control of the posterior teeth, effectively avoiding anchorage loss. This synergistic design of "overall anterior tooth movement + stable posterior tooth anchorage + parametric force application" greatly improves the efficiency and controllability of closing extraction gaps, enabling clear aligners to handle more complex extraction cases.

[0033] 3. Breakthrough in overcoming the structural limitations of traditional manufacturing processes: This invention is entirely based on additive manufacturing (3D printing) technology, freeing it from the constraints of traditional vacuum thermoforming processes on the geometry of orthodontic appliances. This makes it possible to integrate gap-closing parts with complex three-dimensional curves and mechanical structures, which is impossible with traditional processes. This technological approach opens up new possibilities for structural innovation in invisible orthodontic appliances, enabling "structural design" to compensate for deficiencies in "material properties."

[0034] 4. Enhanced control over tooth movement, especially root torque control: The fabrication method incorporates a target position compensation design for the aligner (such as root overcorrection for the "pendulum effect"), which can actively apply torque to control the tooth root, effectively promoting overall tooth movement rather than tilting of the crown. This significantly improves the torque control capability of the clear aligner in the sagittal, vertical, and lateral directions, thereby achieving more ideal orthodontic results and occlusal relationships.

[0035] 5. Maintaining excellent aesthetics and comfort: The main body of the aligner of this invention is still made of transparent material, and the key mechanical structure (gap closing part) is mainly designed in non-frontal viewing areas such as the buccal and lingual sides of the teeth, so as to maintain the inherent advantages of invisible aligners in terms of aesthetics, comfort and self-removability to the greatest extent.

[0036] In summary, this invention, through the combination of structural innovation and advanced manufacturing technology, effectively solves the two major problems of poor controllability and low efficiency faced by invisible orthodontic technology in closing extraction gaps, and significantly improves its clinical application value in complex orthodontic cases. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of the orthodontic appliance.

[0038] Figure 2 This is a schematic diagram of the force application part of the orthodontic appliance.

[0039] Figure 3 A schematic diagram of the force application area of ​​the orthodontic appliance.

[0040] Figure 4 This is a schematic diagram of the vertical parameters of the force-applying part of the orthodontic appliance.

[0041] Figure 5 This is a schematic diagram of the horizontal parameters of the force-applying part of the orthodontic appliance.

[0042] Figure 6 This is a schematic diagram of the overall orthodontic appliance in Example 3.

[0043] Figure 7 This is a side view schematic diagram of the orthodontic appliance in Example 3.

[0044] Figure 8 This is a top view schematic diagram of the orthodontic appliance in Example 3.

[0045] Figure 9 This is a schematic diagram of the overall orthodontic appliance in Example 4.

[0046] Figure 10 This is a schematic diagram of the S3 step design of the orthodontic appliance in Example 4.

[0047] Figure 11 This is a side view of the force-applying part in Example 4.

[0048] Figure 12 This is a top view of the force application part of the orthodontic appliance in Example 4.

[0049] Figure 13 This is a schematic diagram of the overall orthodontic appliance in Example 5.

[0050] Figure 14 This is a schematic diagram of the S3 step design of the orthodontic appliance in Example 5.

[0051] Figure 15 This is a side view of the force application part of the orthodontic appliance in Example 5.

[0052] Figure 16 This is a top view of the force application part of the orthodontic appliance in Example 5.

[0053] Figure 17 This is a schematic diagram of the overall orthodontic appliance in Example 6.

[0054] Figure 18 This is a schematic diagram of the S3 step design of the orthodontic appliance in Example 6.

[0055] Figure 19 This is a side view of the force application part of the orthodontic appliance in Example 6.

[0056] Figure 20 This is a top view of the force application part of the orthodontic appliance in Example 6. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings.

[0058] Example 1

[0059] This embodiment discloses an orthodontic appliance for closing extraction gaps, such as... Figure 1 As shown, this type of orthodontic appliance includes a tooth-correcting part 1, a posterior tooth-wrapping part 2, and a gap-closing part 3.

[0060] The anterior orthodontic unit 1 consists of a clear aligner that completely covers the anterior teeth area, including the central incisors, lateral incisors, and canines, enabling proper alignment of the teeth within the anterior cavity. Simultaneously, it has no additional structure when viewed from the front, maintaining the same aesthetics as conventional clear aligners. The posterior orthodontic unit 2 consists of a shell-shaped aligner that independently covers the premolars and molars, providing retention and anchorage for applying force to close gaps. Furthermore, because each posterior tooth is individually aligned, it allows for more flexible control of individual teeth and overall control of the anterior and posterior teeth areas. Figure 2 As shown, the gap closing part 3 is distributed on both sides of the canine area of ​​the anterior orthodontic part 1 and the buccal and lingual sides of the posterior tooth wrapping part. The gap closing part 3 consists of an attachment retaining part 31 and a force applying part 32. The attachment retaining part 31 is directly opposite the attachment bonding area on the tooth surface to ensure the stability and reliability of the orthodontic force application site. The force applying part 32 consists of a connector that is connected to the attachment retaining part 31 and is used to apply orthodontic force.

[0061] like Figure 3 As shown, based on the different positions and functions of the force-applying part 32 in the dental arch, the connector of the force-applying part 32 is further divided into three functional sections: canine-premolar section 321, premolar-molar section 322, and molar-molar section 323, wherein:

[0062] The canine-premolar segment 321 is the main force-applying segment that crosses the extraction space and achieves space closure. By independently setting its parameters, the efficiency and method of anterior tooth retraction (such as controlling the torque during retraction) and the degree of posterior tooth anchorage consumption can be precisely controlled.

[0063] The premolar-molar segment 322 is a key segment for controlling the stability and mobility of the posterior anchorage unit. By independently setting its parameters, the posterior anchorage can be strengthened, or the posterior teeth can be driven to move forward, and the movement pattern of the posterior teeth (such as overall movement or tilting movement) can be controlled.

[0064] The molar-molar segment 323 is a stable segment that maintains the posterior arch morphology and intermolar width. By setting its parameters, the stability of the terminal molars can be ensured, providing a solid posterior anchor point for the entire orthodontic system.

[0065] By independently adjusting the morphological parameters of the connectors in different segments, more precise differentiated biomechanical control can be achieved, thereby addressing complex clinical needs.

[0066] like Figure 4 , Figure 5 As shown, the shape of the connector is defined by the following key parameters:

[0067] 1) Parameter a: Indicates the vertical thickness of the force-applying part 32 connector. This thickness determines the strength of the vertical orthodontic force provided by the connector to both sides. The thicker the connector, the greater the stiffness, and the greater the vertical orthodontic force provided for the same amount of tooth movement. It is suitable for the treatment of vertical elongation and intrusion of local teeth, as well as the adjustment of the longitudinal arch curve and sagittal torque of the entire dentition.

[0068] 2) Parameter n: represents the number of bends in the vertical direction of the force-applying part 33 connecting body. The more bends, the better the vertical elasticity of the force-applying part. Under the same parameter a, the larger the value of n, the lower the vertical stiffness, which means that the vertical corrective force is gentler and the elastic force range is greater;

[0069] 3) Parameter h: represents the height of the vertical bending peak of the connecting body of the force application part 32. Under the same a and n values, the larger the h value, the gentler the vertical corrective force and the greater the elastic force range.

[0070] 4) Parameter b: Indicates the horizontal thickness of the force-applying part 32 connector. This thickness determines the strength of the horizontal corrective force provided by the connector to both sides. The thicker the connector, the greater the stiffness, and the greater the horizontal corrective force provided for the same amount of tooth movement. It is suitable for adjusting local buccal and lingual tooth movements and tooth rotations, as well as adjusting the width of the entire dental arch and the lateral torque.

[0071] 5) Parameter m: represents the number of horizontal curvatures of the force-applying part 32 connecting body. The more curvatures, the better the horizontal elasticity of the force-applying part. Under the same parameter b, the larger the value of m, the lower the horizontal stiffness, which means that the horizontal corrective force is gentler and the elastic force range is greater;

[0072] 6) Parameter w: represents the width of the crest of the horizontal bending of the connecting body of the force application part 32. Under the same b and m values, the larger the w value, the gentler the horizontal corrective force and the greater the elastic force range.

[0073] Example 2

[0074] Based on Example 1, this example discloses a method for manufacturing such an orthodontic appliance for closing extraction gaps, specifically including the following steps:

[0075] S1. Obtain a model of the patient's dentition: A digital model of the patient's dentition is obtained through oral scanning, which is used to further complete the segmentation of the teeth and the design of the terminal occlusion.

[0076] S2. Define the target position and attachment morphology for step-by-step tooth movement: Design the step-by-step tooth movement from initial occlusion to terminal occlusion, and determine the attachment morphology to be used based on the tooth movement pattern.

[0077] S3. Design of Target Position Compensation for Orthodontic Appliances: For each step of tooth movement target position, the appliance is not directly generated based on this shape, but rather "overcorrection" or "mechanical compensation" is designed. For example, to counteract the phenomenon of crown movement preceding tooth movement caused by the "pendulum effect" common in invisible aligners, additional space compensation is given in advance in the direction of tooth root movement when designing the appliance shape. That is, a tooth root movement amount exceeding the target position of that step is designed, thereby actively applying torque to control the tooth root and achieving a more ideal overall movement;

[0078] S4. Constructing the anterior orthodontic treatment area: The anterior tooth crowns are offset and shelled outwards as a whole to form the anterior orthodontic treatment area;

[0079] S5. Constructing the posterior tooth wrapping: Select the buccal and lingual surfaces and occlusal surfaces of each posterior tooth individually, and offset and shell them to add the posterior tooth wrapping;

[0080] S6. Constructing the anterior orthodontic unit: Treat the crowns of the anterior teeth (central incisors, lateral incisors, and canines) as a continuous whole, offset and shell them along the tooth surface normal to form a fully enclosed anterior orthodontic unit, ensuring coordinated movement when the anterior teeth are retracted as a whole.

[0081] S7. Constructing the posterior tooth wrapping: For each premolar and molar, the crown data is extracted independently, and the shell is offset and extruded along the buccal and lingual surfaces and (occlusal) surfaces respectively to form independent shell-like wrapping structures, which serve as independent control units.

[0082] S8. Constructing the gap closing mechanism: Using the canine attachment clasp and the posterior tooth attachment clasp 31 as force application points, the force-applying connector between the two is generated parameterizedly through algorithm-driven processing. Based on clinical needs (such as requiring a large force to retract the anterior teeth, a gentle and continuous force, or simultaneous control of torque and vertical height), key parameters (a, n, h, b, m, w) are directly input to adjust the three-dimensional geometry of the connector, thereby precisely controlling its stiffness, force value, and elastic range in different directions.

[0083] S9. Manufacturing: The final optimized 3D model of the integrated orthodontic appliance is imported into a 3D printer. Medical-grade photosensitive resin is used for printing. After printing, post-processing (such as cleaning and secondary photocuring) is performed to remove the support structure and polish the appliance to obtain the final product.

[0084] Example 3

[0085] Based on Examples 1 and 2, this example discloses an application instance whose goal is to achieve balanced alignment through stiffness compensation during the preparation stage before gap closure, as detailed below:

[0086] 1. Clinical scenarios and biomechanical goals

[0087] like Figure 6 As shown, after tooth extraction and before formally closing the gap, it is necessary to align both the anterior and posterior teeth simultaneously. Due to the presence of the extraction gap, the effective span of the canine-premolar segment 321 is relatively large, resulting in lower structural stiffness. In contrast, the premolar-molar segment 322 and molar-molar segment 323 in the posterior tooth region have no gap, a short span, and higher stiffness. To avoid uneven movement of the anterior and posterior teeth due to uneven force during alignment, this embodiment employs a stiffness compensation design: specifically, the structural parameters of the segment 321 with the larger span are intentionally increased to make its stiffness close to that of the gapless premolar-molar segment 322 and molar-molar segment 323. This ensures that under the same displacement, the anterior and posterior teeth experience similar orthodontic forces, achieving synchronous and efficient alignment of the entire dentition.

[0088] 2. The partitioning parameter design strategy employs stiffness compensation, specifically as follows: Figure 7 , Figure 8 As shown;

[0089] 1) Canine-premolar segment: To compensate for the large span and low stiffness caused by extraction gaps, improve its structural stiffness, and match the generated orthodontic force with the posterior segment:

[0090] Parameter a (vertical thickness): 2-4mm, thicker than the rear section, to improve rigidity and prevent vertical loss of control of teeth during alignment;

[0091] Parameter n (number of vertical curves): 4-6 curves, increasing elasticity and force range;

[0092] Parameter h (vertical crest height): 3-5mm, to maintain necessary vertical elasticity;

[0093] Parameter b (horizontal thickness): 1-2mm, thicker than the rear section, directly compensating for the stiffness loss due to the large span;

[0094] Parameter m (horizontal curvature): 2-4 curvatures, fewer curvatures, to maintain appropriate horizontal elasticity;

[0095] Parameter w (horizontal wave crest width): 1-2mm. Narrowing the wave width makes the structure more compact and increases rigidity.

[0096] 2) Premolar-molar and molar-molar segments: These segments have no extraction gaps, short spans, and high rigidity. Therefore, relatively standard or slightly flexible parameter settings are used as the reference for force values.

[0097] Parameter a (vertical thickness): 1-2mm, providing appropriate stiffness;

[0098] Parameter n (number of vertical curves): 4-6 curves, increasing elasticity and force range;

[0099] Parameter h (vertical crest height): 1-2mm, to maintain necessary vertical elasticity;

[0100] Parameter b (horizontal thickness): 1-2mm, directly compensates for the stiffness loss due to the large span;

[0101] Parameter m (number of lateral curves): 0 curves, providing lateral stiffness;

[0102] The parameter w (horizontal wave crest width) is 0mm, which makes the structure more compact and increases rigidity.

[0103] 3. Effects

[0104] 1) Achieving mechanical balance: Although the physical span of segment 321 is larger, its structural stiffness, enhanced by thickening and reducing the number of curves, is approximately the same as that of the shorter posterior tooth segment. This ensures that during alignment, the orthodontic forces experienced by the anterior and posterior tooth segments when the same displacement occurs are similar (e.g., both remain within the ideal light force range of 80-120g).

[0105] 2) Promote coordinated movement: Under the drive of balanced orthodontic force, the anterior and posterior teeth can begin to move synchronously and in a coordinated manner, effectively avoiding problems such as asynchronous alignment and low efficiency caused by weak force in the anterior segment and strong force in the posterior segment.

[0106] 3) Improved treatment efficiency: The balanced force system makes the alignment process of the entire dental arch more stable and efficient, laying a good foundation for the subsequent precise closure of gaps.

[0107] Example 4

[0108] Based on Examples 1 and 2, this example discloses a second application instance, applied to moderate anchorage gap closure during extraction of the first premolar, enhancing stiffness and rocker arch compensation design, as detailed below:

[0109] 1. Clinical Scenario and Biomechanical Goals

[0110] like Figure 9 As shown, extraction of bilateral first premolars is the most common extraction case. The biggest problem with using clear aligners to handle this type of case is that during the gap closure process, the crowns tend to tilt towards the extraction gap, causing the anterior teeth to tilt inward and droop, leading to a deeper overbite and even occlusal trauma. Meanwhile, the posterior teeth tilt forward, resulting in occlusal dysfunction. This embodiment demonstrates how the present invention can efficiently close the gap after first premolar extraction while effectively controlling the torque of the anterior and posterior teeth, thus solving the difficult problems of traditional clear aligners.

[0111] 2. Mechanical compensation design for digital tooth alignment

[0112] Mechanical compensation design is performed in steps S2 and S3:

[0113] 1) Define the target position in step S2: Align the teeth from the initial position to the ideal arch shape, and then design the tooth movement by closing 0.4mm (twice the original) at each step;

[0114] 2) Step S3 involves anti-roller coaster effect compensation design: Based on the preliminary model, a targeted overcorrection design is implemented, the core of which is to simulate a rocking chair arch shape and strengthen anterior tooth torque control. The designed dental arch presents a smooth rocking chair arch shape, with the anterior and posterior ends pressed in and the middle section elongated to level the arch. Based on the sagittal overcorrection, the roots of the anterior teeth (especially incisors and canines) are pre-torqued sagittally posteriorly, while the roots of the posterior teeth are pre-torqued sagittally anteriorly. For example... Figure 10 As shown, in the digital model, the preset root retraction movement is greater than that of the crown, thereby actively constructing a root-controlling torque in the shape of the orthodontic appliance.

[0115] 3. Zonal parameter design strategy (stiffness enhancement to achieve torque control)

[0116] 1) The canine-premolar section is the extraction space area:

[0117] Parameter a (vertical thickness): 3-4mm, significantly thicker than the posterior tooth area, which improves rigidity and also helps to pressure the anterior teeth and reduce deep overbite;

[0118] Parameter n (number of vertical curves): 1-2 curves, using only a single peak of an arch bridge structure to resist dental arch deformation;

[0119] Parameter h (vertical crest height): 1-2mm. A smaller crest height is used to maintain the elasticity of the gap closure. See [reference needed]. Figure 11 ;

[0120] Parameter b (horizontal thickness): 1-3mm, provides horizontal stiffness to maintain dental arch shape;

[0121] Parameter m (horizontal curvature): 0 curvatures, providing lateral stiffness to maintain dental arch shape;

[0122] Parameter w (horizontal wave crest width): 0.5-1mm. Narrowing the wave width makes the structure more compact and increases stiffness. See [link / reference]. Figure 12 .

[0123] 2) Premolar-molar segment and molar-molar segment: This segment has no extraction space, short span, and high rigidity.

[0124] Parameter a (vertical thickness): 1-3mm, providing good stiffness and enabling continuity of vertical control of front and rear teeth;

[0125] Parameter n (number of vertical curves): 1-2 curves, using a single peak of an arch bridge structure to resist dental arch deformation;

[0126] Parameter h (vertical wave crest height): 1-2mm, providing some flexibility, see [reference needed] Figure 11 ;

[0127] Parameter b (horizontal thickness): 1-2mm, provides stiffness and maintains the arch shape of the posterior tooth segment;

[0128] Parameter m (number of lateral curves): 0 curves, providing lateral stiffness;

[0129] Parameter w (horizontal wave crest width): 0.5-1mm, making the structure more compact and increasing rigidity, see [reference]. Figure 12 .

[0130] 4. Effects:

[0131] 1) Active torque control: The torque compensation design, in conjunction with the thickened vertical structure, actively applies a continuous root control torque, effectively guiding the teeth to move as a whole and significantly suppressing the roller coaster effect.

[0132] 2) High-efficiency gap closure: The overall enhanced horizontal stiffness, while ensuring a large range of elastic space, achieves efficient gap closure and stable dental arch morphology.

[0133] 3) Arch curve optimization: The shape of the appliance and the parameterized connector work together to safely level the dental arch while closing gaps.

[0134] Example 5

[0135] Based on Examples 1 and 2, this example discloses a third application instance: closure of the strong anchorage gap after extraction of the first premolar, based on the precise mechanical distribution of implant anchorage, as detailed below:

[0136] 1. Clinical Scenario and Biomechanical Goals

[0137] Extraction of both first premolars combined with implant anchorage for anterior tooth retraction is a classic solution for severe crowding and facial protrusion. However, there is an inherent contradiction when applying clear aligners to this approach: traditional aligners can only achieve a limited movement of about 0.25 mm per set, while implant traction provides continuous and significant retraction force. Once the teeth are moved beyond the aligner's preset position, the aligner itself transforms from a force-applying component into an obstructive element, hindering further tooth movement. This embodiment utilizes the present invention to construct an aligner that can efficiently coordinate with strong implant anchorage. Through increased single-step movement space and optimized three-dimensional control, it ensures synchronous and coordinated movement of the teeth and aligner under continuous traction force. See [link to relevant documentation]. Figure 13 .

[0138] 2. Mechanical compensation design for digital tooth alignment

[0139] Mechanical compensation design is performed in steps S2 and S3:

[0140] 1) Step S2 - Define target position: Align the teeth from the initial position to the ideal arch shape, and plan the steps of tooth movement of the orthodontic appliance according to the distance of 0.4mm inward retraction of each appliance;

[0141] 2) Step S3 - Anterior Tooth Retraction Vertical and Torque Compensation Design: Based on the preliminary model, the anterior tooth region of each appliance is designed for overall intrusion and sagittal posterior rotation of the tooth roots to achieve anterior tooth intrusion and torque control. Since implants are present, no anchorage is required in the molar region; therefore, sagittal anterior rotation of the tooth roots is designed only in the premolars to achieve root torque compensation. See [link to relevant documentation]. Figure 14 .

[0142] 3. Partition Parameter Design Strategy

[0143] 1) Canine-premolar segment:

[0144] Parameter a (vertical thickness): 2-4mm, which improves vertical stiffness and is beneficial for pressure on the anterior teeth, reducing deep overbite;

[0145] Parameters n and h (vertical curvature number and crest height): 0mm, no curvature set to further increase rigidity, see [link to documentation]. Figure 15 ;

[0146] Parameter b (horizontal thickness): 1-2mm. Reducing the horizontal thickness decreases stiffness.

[0147] Parameter m (horizontal curvature): 6-8 curvatures; increasing the number of curvatures improves elasticity and force range.

[0148] Parameter w (horizontal crest width): 1-3mm. Increasing the crest width reduces horizontal stiffness and improves elasticity and force range. See [reference needed]. Figure 16 .

[0149] 2) Premolar-molar and molar-molar segments: These segments have no extraction gaps, short spans, and high rigidity.

[0150] Parameter a (vertical thickness): 1-3mm, providing good stiffness and enabling continuity of vertical control of front and rear teeth;

[0151] Parameters n and h (vertical curvature number and crest height): 0, no curvature is set to further increase rigidity and maintain the posterior teeth as a whole, see [link to documentation]. Figure 15 ;

[0152] Parameter b (horizontal thickness): 1-2mm, provides stiffness and maintains the arch shape of the posterior tooth segment;

[0153] Parameters m and w (horizontal curvature and crest height): 0mm, no curvature is set to further increase rigidity and maintain the posterior teeth as a whole. See [link / reference]. Figure 16 .

[0154] 4. Effects:

[0155] 1) Anterior tooth retraction efficiency: The single-step retraction amount of 0.4mm is designed to effectively match the mechanical characteristics of continuous traction of implants, avoiding the orthodontic appliance from becoming an obstructive element due to excessive tooth movement, and ensuring the continuity and efficiency of the retraction process.

[0156] 2) Three-dimensional control precision: Through the overall indentation and torque compensation design of the anterior tooth area, as well as the stiffness adjustment of the segment (such as increasing the vertical stiffness of the canine-premolar segment to control the anterior teeth and optimizing the horizontal elasticity to guide the gap closure), the ideal retraction and torque maintenance of the anterior teeth are achieved, effectively preventing common problems such as crown tilting and overbite.

[0157] 3) Overall mechanical stability: The parameters of the posterior region are designed to maintain its rigidity as an overall anchorage unit, ensuring the stability and controllability of the orthodontic force system.

[0158] Example 6

[0159] Based on Examples 1 and 2, this example discloses a fourth application instance: closure of weak anchorage gaps after extraction of the second premolar (extraction 5), as detailed below:

[0160] 1. Clinical Scenario and Biomechanical Goals

[0161] Bilateral second premolar extraction is a common clinical practice used to relieve posterior crowding or achieve minor anterior tooth retraction. The challenge lies in the fact that, due to the posterior extraction location, the posterior tooth anchorage units are smaller, resulting in weaker anchorage and making it difficult to provide effective torque control for the anterior teeth during space closure. Simultaneously, posterior teeth are more prone to tilting and migrating mesially (towards the extraction space), further increasing the risk of anchorage loss and occlusal dysfunction. Therefore, space closure in such cases is a complex biomechanical problem requiring extremely high three-dimensional control of the teeth. Traditional clear aligners struggle to precisely control such complex biomechanical mechanisms. To address this challenge, this embodiment demonstrates how the flexible control capabilities provided by this invention can be used to develop targeted treatment strategies.

[0162] 2. Mechanical compensation design for digital tooth alignment

[0163] like Figure 17-20 As shown, mechanical compensation design is performed in steps S2 and S3:

[0164] 1) Define the target position in step S2: Align the teeth from the initial position to the ideal arch shape, and then design the tooth movement by closing 0.45mm at each step;

[0165] 2) In step S3, tooth displacement mechanical compensation is performed: First, posterior tooth anchorage preparation and vertical control are performed. For the first and second molars distal to the extraction gap, continuous mesial root movement (i.e., mesial control of crown distal root) is designed to achieve torque compensation and pre-strengthen posterior tooth anchorage. At the same time, indentation force is applied to the second molar to counteract the common tendency of arch elongation during gap closure.

[0166] Furthermore, torque and vertical control of the anterior teeth are achieved. The entire anterior tooth region is designed to move the roots distally (positive torque compensation) to counteract the crown tilting that is prone to occur during retraction; at the same time, by designing the appropriate elongation of the first premolar, force is provided to the pressure in the anterior tooth region to maintain a normal overbite relationship.

[0167] 3. Partition Parameter Design Strategy

[0168] 1) Canine-premolar segment:

[0169] Parameter a (vertical thickness): 1-3mm, providing moderate rigidity support to facilitate depressing the anterior teeth;

[0170] Parameter n (number of vertical curves): 1-2 curves, using only a single peak with a U-shaped structure to provide some elastic support;

[0171] Parameter h (vertical peak height): 1-2mm, providing elastic support and increasing the depressor amount of a single aligner;

[0172] Parameter b (horizontal thickness): 1-3mm, provides horizontal stiffness to maintain dental arch shape;

[0173] Parameters m and w (horizontal curve number and peak height): 0mm, no curve is set to further increase rigidity and maintain the width of the anterior tooth area.

[0174] 2) Premolar-molar region:

[0175] Parameter a (vertical thickness): 2-3mm, provides good stiffness and enables continuous control of the vertical direction of the front and rear teeth;

[0176] Parameter n (vertical curvature): 5-7 curvatures provide good elasticity, allowing the 0.45mm gap closing force to be continuously expressed and reducing attenuation;

[0177] Parameter h (vertical wave crest height): 2-4mm, providing flexibility;

[0178] Parameter b (horizontal thickness): 1-3mm, provides stiffness and maintains the arch shape of the posterior tooth segment;

[0179] Parameter m (number of lateral curves): 0 curves, providing lateral stiffness;

[0180] Parameter w (horizontal crest width): 0mm, increases lateral stiffness.

[0181] 3) Molar-molar segment 323:

[0182] Parameter a (vertical thickness): 1-3mm, providing good stiffness and enabling the transmission of vertical control and torque control for front and rear teeth;

[0183] Parameter n (number of vertical curves): 1-3 curves, using an S-shaped structure to provide better flexibility;

[0184] Parameter h (vertical wave crest height): 1-3mm, providing some flexibility;

[0185] Parameter b (horizontal thickness): 1-3mm, provides stiffness and maintains the arch shape of the posterior tooth segment;

[0186] Parameter m (number of lateral curves): 0 curves, providing lateral stiffness;

[0187] Parameter w (horizontal crest width): 0mm, maintaining a horizontal bow shape.

[0188] 4. Effects:

[0189] 1) Mechanical Control: The solution successfully addressed the core challenge posed by weak anchorage. Through the S3 step of mesial root movement and intrusion control of the first and second molars, the posterior anchorage was effectively prepared and strengthened, significantly suppressing its posterior tilting and elongation tendencies, providing stable posterior support for anterior tooth retraction. Simultaneously, positive torque compensation in the anterior region and the elongation design of the first premolar precisely offset the risks of excessive lingual tilting of the crown and deepening of overbite during retraction, achieving overall control of the anterior teeth.

[0190] 2) Gap Closure Efficiency and Stability: The design of the zonal parameters played a crucial role. The premolar-molar segment 32, with its multiple vertical bends (n=6, h=3mm), provided a continuous and gentle elastic force for the relatively large single-step movement of 0.45mm, ensuring efficient and smooth transmission of gap-closing power and avoiding rapid force attenuation. Other segments, with their moderate thickness and limited number of bends, provided necessary rigidity in key areas (such as the horizontal direction of the canine-premolar segment and the molar segment), effectively maintaining the overall stability of the dental arch morphology and preventing unnecessary deformation.

[0191] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. An orthodontic appliance for closing extraction gaps, characterized in that, It includes an anterior orthodontic unit, a posterior wrapping unit, and a gap closing unit. The anterior orthodontic unit completely wraps the anterior teeth, and the posterior wrapping unit wraps each posterior tooth individually. The gap closing unit includes a force-applying component and a retention component. The force-applying component includes a connector and a retention component. The connector spans the gap between the anterior orthodontic unit and the posterior wrapping unit and / or the gap between adjacent posterior wrapping units. The retention component is located on the surface of the anterior orthodontic unit or the posterior wrapping unit, and the connector is retained by the retention component.

2. The orthodontic appliance according to claim 1, characterized in that, Both the lingual and lip sides are equipped with gap closing components.

3. The orthodontic appliance according to claim 1 or 2, characterized in that, The retaining component is a clamping component, and the connecting body is strip-shaped. The retaining component clamps the connecting body.

4. The orthodontic appliance according to claim 3, characterized in that, The connector is provided with a vertically bent portion and / or a horizontally bent portion.

5. The orthodontic appliance according to claim 1, characterized in that, The anterior orthodontic unit covers the central incisors, lateral incisors, and canines.

6. A method for manufacturing an orthodontic appliance as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Obtain a digital model of the patient's dentition and complete tooth segmentation and final occlusion design; S2. Plan the step-by-step movement path from the initial dentition to the terminal dentition, and design the attachment morphology; S3. Perform mechanical compensation design for the step-by-step movement target position, wherein the mechanical compensation design includes overcorrection of the root movement direction; S4. Based on the compensated digital model, construct the anterior orthodontic area and the posterior encapsulation area respectively; S5. Parametrically construct the gap closing part. By setting the morphological parameters of the connector, a three-dimensional structure with predetermined mechanical properties is generated. S6. The orthodontic appliance is manufactured in an integrated manner using additive manufacturing technology.

7. The manufacturing method according to claim 6, characterized in that, Step S5 also includes: The connector located between the canine and the premolar is configured as the main force application zone across the extraction space to control the retraction of the anterior teeth and the loss of the anchorage of the posterior teeth. The connector located between the premolar and molar is configured as a key area for controlling the stability and movement of the posterior anchorage unit; The connectors located between molars are configured as a stable zone to maintain the shape and width of the posterior segment of the dental arch.

8. The manufacturing method according to claim 7, characterized in that, In step S5, the morphological parameters of the connector are designed as follows: Adjust the vertical thickness of the connector to meet the stiffness of the connector in the vertical direction, adjust the vertical curvature of the connector to meet the corrective force value of the connector in the vertical direction, and adjust the vertical crest height of the connector to meet the elastic force range of the connector in the vertical direction. Adjust the horizontal thickness of the connector to meet the horizontal stiffness of the connector, adjust the horizontal curvature of the connector to meet the horizontal corrective force value of the connector, and adjust the horizontal crest height of the connector to meet the horizontal elastic force range of the connector.

9. The manufacturing method according to claim 8, characterized in that, The morphological parameters of the connectors in the main force application zone, critical zone, and stable zone are designed independently.

10. The manufacturing method according to any one of claims 6-9, characterized in that, The additive manufacturing technology is photopolymerization 3D printing, and the material used is medical-grade photosensitive resin.

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