Invisible appliance with improved root control structure

Abstract

The utility model discloses an invisible orthodontic appliance with an improved root control structure. The invisible orthodontic appliance comprises an invisible orthodontic appliance body and the improved root control structure, the improved root control structure is arranged corresponding to at least one of the one-third position of the lip face neck area of a single anterior tooth and the one-third position of the mesial adjacent face neck area and / or the distal tooth tip area, and is arranged on the inner surface of a cavity, used for containing teeth, of the invisible orthodontic appliance body. The improved root control structure is a solid structure formed by locally thickening the invisible orthodontic appliance body relative to the inner surface of the cavity to the tooth surface of the anterior tooth, and extends along at least one of the near-far-middle direction and the lip-tongue direction; wherein the anterior teeth are selected from at least one of incisor teeth and canine teeth.

Description

Technical Field

[0001] This utility model relates to the field of invisible orthodontic technology, specifically to an invisible orthodontic device with a modified root control structure. Background Technology

[0002] With the development of computer-aided design / computer-aided manufacturing (CAD / CAM) technology, clear aligners have been widely used in orthodontic treatment due to their aesthetic and comfort advantages. However, clear aligners still have significant shortcomings in achieving complex tooth movements, especially in torque control. Torque, as one of the six key elements of normal occlusion, is crucial for the aesthetics and function of the anterior teeth, but its expression in clear aligners is often unsatisfactory.

[0003] When designing lingual torque for the maxillary incisors, the teeth are more prone to labial tilting centered on the middle third of the root. This means that the expression of lingual torque is insufficient, manifesting more as labial tilting of the crown rather than the ideal palatal movement of the root. This indicates that the clear aligner fails to create an effective force couple between the crown and root, resulting in insufficient control over the root. Clinical research data clearly reveals this systemic deficiency. Existing studies show that clear aligners still have significant errors in torque control: when the designed torque exceeds 5°, its expression efficiency is only about 50%. Even when using traditional root control structures or attachments, if the torque requirement for anterior teeth exceeds 10°, there may still be a torque loss of about 50%. This indicates that traditional auxiliary structures have limitations in achieving precise root control.

[0004] The fabrication of traditional root control structures relies on a combination of hot-pressing film technology and master mold design. The process is as follows:

[0005] Master Model Design and 3D Printing: First, a specific groove is designed on the labial cervical region of the incisor on the digital dental model using computer-aided design (CAD) software. The position and shape of this groove correspond to the protrusions of the root control structures on the final dental crown. Subsequently, this model with the groove is 3D printed to create a physical master model.

[0006] Molding by pressure molding: When making invisible braces, a flat thermoplastic polymer film is placed over the master mold and heated. After the film softens, it is pressed tightly against the surface of the master mold using negative pressure.

[0007] The formation mechanism of the "concave" turning into "convex": Under pressure, the softened diaphragm will embed into and fill the groove structure of the neck of the incisor in the master mold. After the diaphragm cools and solidifies and is removed from the master mold, the groove that was originally on the master mold will form a protrusion structure on the corresponding inner surface of the crown, which is the root control structure in the traditional sense.

[0008] Its clinical defects manifest in the following two aspects:

[0009] Traditional root control structures achieve root control by creating localized "twisted" structures on a uniformly thick orthodontic appliance membrane. However, in thermoforming processes, the appliance membrane thins at the gingival margin, resulting in lower rigidity in this area. Clinically, this can lead to decreased fit between the tooth and the appliance in this area, resulting in insufficient force applied to the root and a dominant force applied to the crown. This directly explains why unintended coronal labial tilting occurs instead of root control movement.

[0010] Current attempts to enhance root control (including the use of traditional root control structures) may lead to abnormal periodontal ligament stress distribution. Studies have shown that stress is primarily concentrated in the apical region and the labial cervical margin. When the root control structure is excessively thick (e.g., reaching 0.4 mm and 0.5 mm), abnormal stress concentration can also occur in the mesial cervical margin. This suboptimal stress distribution may increase the potential risk of external root resorption, a complication that must be avoided in orthodontic treatment.

[0011] There is currently a lack of systematic research on the improvement of control root structure, especially on the impact of its local thickening design on torque control performance.

[0012] Therefore, there is an urgent need in this field for a more efficient and better structure for invisible aligners that can adapt to individual differences, in order to solve the problems of insufficient torque expression, poor control of tooth root movement, and the risk of tooth root resorption due to stress concentration. Utility Model Content

[0013] To address these issues, this invention proposes a clear aligner with a modified root control structure, comprising a clear aligner body and a modified root control structure. The modified root control structure is positioned at least one-third of the labial cervical region and one-third of the mesial proximal cervical region of a single anterior tooth, and / or the distal cusp region, and is disposed on the inner surface of the cavity of the clear aligner body used to accommodate the tooth. The modified root control structure is a solid structure formed by locally thickening the clear aligner body relative to the inner surface of the cavity towards the tooth surface of the anterior tooth, and extends along at least one direction: mesiodistal and labiolingual. The anterior tooth is selected from at least one of incisors and canines. Through structural improvement, the modified root control structure can more effectively control anterior tooth torque and tooth axial tilt compared to traditional root control structures.

[0014] Preferably, the clear aligner body has at least one modified root control structure corresponding to a single anterior tooth. By setting the modified root control structure at a single location or in pairs on the tooth, the torque requirement for controlling the tooth and the axial tilt requirement for controlling the tooth can be selectively met.

[0015] Preferably, the modified root control structure is located at one-third of the cervical region of the mesial proximal surface of the canine and one-third of the distal cusp region of the canine, extending labiolingually. The coordinated arrangement of these labiolingual root control structures enables control of the canine's tooth axis, thereby completing distal movement of the canine.

[0016] Preferably, the length of the improved root control structure is 4 mm and the width is 1 mm.

[0017] Preferably, the thickness increase of the modified root control structure relative to the inner surface ranges from 0.1 mm to 0.5 mm. Experiments have shown that within this range, the modified root control structure performs better than the traditional root control structure in meeting the torque requirements of the teeth.

[0018] Preferably, the thickness increase of the modified root control structure relative to the inner surface is 0.25 mm. When the thickness increase is 0.25 mm, the modified root control structure achieves the highest torque expression success rate.

[0019] Compared with existing torque control technology for invisible aligners, especially traditional root control structures, this invention brings the following significant benefits through structural and manufacturing innovations:

[0020] 1. Significantly improves torque control efficiency and accuracy, achieving more ideal tooth root movement:

[0021] Currently, applying torque often results in unintended labial tilting of the crown, with the tooth rotation center located in the middle of the root, leading to poor root movement. The "twisted" structure of traditional root control appliances acts more like a fulcrum, resulting in inefficient force transmission. In contrast, the "locally thickened" structure of this invention directly enhances the stiffness and thrust of the appliance in this area, thus achieving superior mechanical effects with less macroscopic deformation. Through this locally thickened modified root control structure, under the same thickness parameters, this invention can more effectively move the tooth rotation center towards the occlusal direction than traditional root control structures. This means that with similar or smaller crown movement, greater palatal root movement is achieved, making tooth movement closer to the clinically required root control movement.

[0022] 2. Provides a predictable and efficient clinical solution: This invention determines optimized design parameters (such as a protrusion thickness of 0.25 mm) through biomechanical analysis, providing a predictable and efficient torque control tool for clinical use. It is expected to significantly reduce the current torque expression failure rate of up to 40-50%, and reduce the need for additional orthodontic appliances or switching to fixed appliances during the fine-tuning stage. Attached Figure Description

[0023] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the present invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0024] Figure 1 The side cross-sectional diagrams of the invisible orthodontic appliances with no control root structure, using a traditional control root structure, and using the improved control root structure proposed in this utility model are shown respectively.

[0025] Figure 2 The diagrams show a 3D structural comparison of clear aligners with no control root structure, those using a traditional control root structure, and those using the improved control root structure proposed in this invention.

[0026] Figure 3 A schematic diagram of the improved root control structure proposed in this invention is shown for applying to canines or incisors;

[0027] Figure 4 A schematic diagram of the forces acting on a canine with the improved root control structure proposed in this invention is shown.

[0028] Figure 5 A front cross-sectional schematic diagram of the improved root control structure proposed in this invention applied to a canine is shown;

[0029] Figure 6(a) shows the tooth movement trend of a clear aligner without a controlled root structure;

[0030] Figure 6(b) shows the tooth movement trend of a clear aligner with a traditional root control structure;

[0031] Figure 6(c) shows the tooth movement trend of the invisible aligner with the improved root control structure proposed in this invention;

[0032] Figure 7(a) shows the stress distribution of the central incisor in relation to a clear aligner without root control structure;

[0033] Figure 7(b) shows the stress distribution of the central incisors in groups B1-B3 using a traditional root-control structure invisible aligner;

[0034] Figure 7(c) shows the stress distribution of the central incisors in groups B4-B6 using a traditional root-control structure invisible aligner;

[0035] Figure 7(d) shows the stress distribution of the central incisors in groups C1-C3 of the invisible orthodontic appliance with the improved root control structure proposed in this invention;

[0036] Figure 7(e) shows the stress distribution of the central incisors in groups C4-C6 of the invisible orthodontic appliance with the improved root control structure proposed in this invention;

[0037] Figure 8 A comparative schematic diagram shows the effect of thickness variation on tooth movement distance between a traditional root control structure clear aligner and a clear aligner with the improved root control structure proposed in this invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1-Clear aligner without root control structure; 2-Tooth; 3-Clear aligner with traditional root control structure; 4-Traditional root control structure; 5-Clear aligner with modified root control structure; 6-Modified root control structure; 7-Cavity. Detailed Implementation

[0040] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the relevant utility model and not intended to limit the scope of the utility model. Furthermore, it should be noted that, for ease of description, only the parts relevant to the utility model are shown in the accompanying drawings.

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] To address the shortcomings of existing clear aligners, such as insufficient torque control efficiency in traditional root control structures, tendency to cause labial tilting of the crown instead of ideal palatal root movement, and potential root resorption risks due to stress concentration, this invention aims to provide an improved clear aligner. Its main objective is to optimize the root control structure to improve the efficiency of root torque control for the maxillary anterior teeth, especially the central incisors, and to control tooth axis inclination, thereby achieving more precise and safer tooth movement.

[0043] Figure 1 and Figure 2 The diagrams show comparative structural and 3D structural diagrams of clear aligners using a non-controlling root structure, a traditional controlling root structure 4, and the improved controlling root structure 6 proposed in this invention. Group A represents the clear aligner 1 without a controlling root structure; Group B represents the clear aligner 3 using a traditional controlling root structure; and Group C represents the clear aligner 5 using the improved controlling root structure.

[0044] The improved root control structure of the invisible aligner 5 proposed in this invention includes an invisible aligner body and the improved root control structure 6. The improved root control structure 6 is set in a specific cervical region and / or distal cusp region of a single anterior tooth, and is disposed on the inner surface of the cavity 7 of the invisible aligner body used to accommodate the tooth. The improved root control structure 6 is a solid structure formed by locally thickening the invisible aligner body relative to the inner surface of the cavity 7 towards the tooth surface of the anterior tooth, and extends along a predetermined direction. The anterior tooth is selected from at least one of incisors and canines; the specific cervical region is selected from at least one-third of the labial cervical region and one-third of the mesial proximal cervical region; and the predetermined direction is selected from at least one of mesiodistal and labiolingual directions. Through structural improvement, the improved root control structure 6 is a locally thickened structure formed in the labial cervical region of the aligner towards the tissue surface, which is different from the uniform thickness "twisted" structure of traditional root control structures.

[0045] It is worth noting that in oral medicine, the mesial-distal direction can encompass the extension from the mesial surface to the distal surface, or the extension from the distal surface to the mesial surface. Similarly, the labiolingual direction in oral medicine can encompass the extension from the lips to the tongue and the extension from the tongue to the lips.

[0046] In a specific embodiment, the invisible aligner body has at least one modified root control structure corresponding to a single anterior tooth. By setting the modified root control structure at a single location or in pairs on the tooth, the torque requirement for controlling the tooth and the axial tilt requirement for controlling the tooth are selectively met.

[0047] In one embodiment, such as Figure 3 As shown, the modified root control structure 6 is located at one-third of the labial cervical margin of the incisors or canines of the upper and lower jaws and extends along the mesiodistal direction. The torque requirement of the incisors is achieved by extending along the mesiodistal direction.

[0048] like Figure 4 and Figure 5 As shown, in one embodiment, the modified root control structure 6 is located at one-third of the mesial cervical region and one-third of the distal cusp of the canine, extending labiolingually. The distal movement of the canine is achieved by the placement of the root control structure extending labiolingually. The torques formed by the mesial thickening point and the distal thickening point result in greater root movement during distal movement of the canine, favoring overall distal movement of the root control structure to avoid tilting during distalization.

[0049] To further demonstrate the superiority of the invisible orthodontic appliance 5 with the improved root control structure proposed in this utility model, taking the maxillary central incisor as an example, the biomechanical effect of the invisible orthodontic appliance with the improved root control structure is explained based on three-dimensional finite element analysis.

[0050] The method for constructing an invisible orthodontic appliance with a modified root control structure based on three-dimensional finite element analysis is as follows:

[0051] A three-dimensional finite element model including the maxilla, periodontal ligament, dentition, accessory devices, and orthodontic appliance is established. A locally thickened structure is constructed in the labial cervical margin region of the appliance on the target tooth (e.g., the maxillary central incisor) using computer-aided design (CAD) to form the modified root control structure 6.

[0052] Different thickness parameters of the improved root control structure 6 are set, and the displacement trend of the tooth and the periodontal ligament stress distribution are simulated by finite element analysis when a target torque (such as 1° palatal root torque) is applied. The displacement ratio (C / R) of the crown and root and the stress cloud map under different thickness parameters are compared and analyzed. The optimized thickness that can achieve the maximum root movement and the stress distribution is selected. Based on the selected optimized thickness, the final digital model of the personalized invisible aligner for 3D printing is generated.

[0053] An adult patient with Angle Class II Division 2 malocclusion and healthy periodontium was selected, and their maxillofacial cone-beam computed tomography (CBCT) data were obtained. The CBCT data were used to perform 3D reconstruction of the maxilla and maxillary dentition using Mimics software (version 21.0) to obtain an initial model, which was then exported as an STL file.

[0054] The STL model was imported into Geomagic Wrap software (2021 version) for optimization and smoothing to generate a solid model. A periodontal ligament (PDL) layer of uniform thickness (0.25 mm) was created on all root surfaces. The teeth and periodontal ligament were subtracted from the maxillary model using Boolean operations to obtain the alveolar socket model.

[0055] The maxillary central incisor is rotated counterclockwise by 1° around its crown center to simulate a 1° root-lingual torque design. Based on this model of the dentition and accessory components after tooth alignment, its surface is offset outward by 0.75 mm to generate the initial shape of the orthodontic appliance.

[0056] A modified root control structure is designed at one-third of the cervical margin of the maxillary central incisor on the labial surface of the orthodontic appliance. Specifically, the inner surface of the appliance is locally thickened to form a raised structure with a length of 4 mm and a width (along the tooth's long axis) of 1 mm. The thickness h of this raised structure relative to the inner surface of the appliance is a key parameter of this invention. In this embodiment, six subgroups (C1-C6) with h = 0.1, 0.2, 0.25, 0.3, 0.4, and 0.5 mm are designed for comparison with the traditional root control structure group (B1-B6 groups) and the group without auxiliary structures (Group A, the control group). For the traditional root control structure group, the thickening thickness is the thickness of the appliance's recess.

[0057] All components (maxilla, dentition, periodontal ligament, appendages, and appliance) were assembled into a complete model in Solidworks, and then imported into Ansys Workbench (version 23.0) for mesh generation and mechanical analysis. The material properties of each component were set to linear elastic, isotropic, and homogeneous, with specific parameters set according to the default parameters (for example, the elastic modulus of the appliance material is approximately 2000 MPa, and the periodontal ligament is approximately 0.7 MPa).

[0058] Set boundary conditions: Fix the upper region of the maxilla away from the dentition. Define contact relationships: The periodontal ligament and tooth root, alveolar bone, and accessory devices and crown are "bonded contact"; the appliance and tooth / accessory device surfaces are "frictional contact", with a friction coefficient set to 0.2.

[0059] The simulation analysis examined the initial displacement behavior (including crown and apical displacement) of the right maxillary central incisor and the von Mises stress distribution of its periodontal ligament when the orthodontic appliance was inserted and an attempt was made to return the tooth to its preset position. Figures 6(a)-6(c) The colors of the legend bars used, from bottom to top, represent the progression of displacement distance. Figure 7(a)-7(e) The legend bars used, with colors from bottom to top, represent the progression of stress magnitude.

[0060] In Figure 6(a), the color values ​​corresponding to Group A from bottom to top are as follows: the first interval from bottom to top: 0.018771mm to 0.026522mm; the second interval from bottom to top: 0.026522mm to 0.034273mm; the third interval from bottom to top: 0.034273mm to 0.042024mm; the fourth interval from bottom to top: 0.042024mm to 0.049775mm; and the fifth interval from bottom to top: 0.018771mm to 0.026522mm. The value range is from 0.042024mm to 0.057526mm. The color value range corresponding to the sixth interval is from 0.057526mm to 0.065277mm, the color value range corresponding to the seventh interval is from 0.065277mm to 0.073028mm, the color value range corresponding to the eighth interval is from 0.073028mm to 0.080779mm, and the color value range corresponding to the ninth interval is from 0.080779mm to 0.088530mm.

[0061] In Figure 6(b), the color values ​​corresponding to group B1 from bottom to top are as follows: the first interval from bottom to top: 0.018771mm to 0.026522mm; the second interval from bottom to top: 0.026522mm to 0.034273mm; the third interval from bottom to top: 0.034273mm to 0.042024mm; the fourth interval from bottom to top: 0.042024mm to 0.049775mm; and the fifth interval from bottom to top: ... The value range is from 0.049775mm to 0.057526mm. The color value range corresponding to the sixth interval is from 0.057526mm to 0.065277mm, the color value range corresponding to the seventh interval is from 0.065277mm to 0.073028mm, the color value range corresponding to the eighth interval is from 0.073028mm to 0.080779mm, and the color value range corresponding to the ninth interval is from 0.080779mm to 0.088530mm.

[0062] In Group B2, the color values ​​for the first interval from bottom to top correspond to a range of values: 0.032804mm to 0.035612mm; the second interval, 0.035612mm to 0.038419mm; the third interval, 0.038419mm to 0.041226mm; the fourth interval, 0.041226mm to 0.044034mm; and the fifth interval, from bottom to top, corresponds to a range of values... The color values ​​for the sixth interval range from 0.044034mm to 0.046841mm, the seventh interval from 0.049649mm, the eighth interval from 0.052456mm, and the ninth interval from 0.055263mm to 0.058071mm.

[0063] In Group B3, the color values ​​for the first interval from bottom to top correspond to a range of 0.035005mm to 0.036785mm; the second interval from 0.036785mm to 0.038564mm; the third interval from 0.038564mm to 0.040344mm; the fourth interval from 0.040344mm to 0.042124mm; and the fifth interval... The color values ​​for the sixth interval range from 0.042124mm to 0.043904mm, the seventh interval ranges from 0.045684mm to 0.047463mm, the eighth interval ranges from 0.047463mm to 0.049243mm, and the ninth interval ranges from 0.049243mm to 0.051023mm.

[0064] In group B4, from bottom to top, the color values ​​for the first interval are 0.037246mm to 0.038353mm, the second interval is 0.038353mm to 0.039460mm, the third interval is 0.039460mm to 0.040566mm, the fourth interval is 0.040566mm to 0.041673mm, and the fifth interval is... The color values ​​for the sixth interval are 0.042780mm to 0.043887mm, the seventh interval is 0.043887mm to 0.044994mm, the eighth interval is 0.044994mm to 0.046100mm, and the ninth interval is 0.046100mm to 0.047207mm.

[0065] In group B5, the color values ​​for the first interval from bottom to top correspond to a range of 0.039579mm to 0.042152mm; the second interval from 0.042152mm to 0.044725mm; the third interval from 0.044725mm to 0.047297mm; the fourth interval from 0.047297mm to 0.049870mm; and the fifth interval... The color values ​​for the sixth interval range from 0.049870mm to 0.052442mm, the seventh interval ranges from 0.055015mm to 0.057588mm, the eighth interval ranges from 0.057588mm to 0.060160mm, and the ninth interval ranges from 0.060160mm to 0.062733mm.

[0066] In group B6, from bottom to top, the color values ​​corresponding to the first interval are 0.041220mm to 0.045609mm, the second interval is 0.045609mm to 0.049998mm, the third interval is 0.049998mm to 0.054387mm, the fourth interval is 0.054387mm to 0.058776mm, and the fifth interval is... The color values ​​for the sixth interval range from 0.058776mm to 0.063165mm, the seventh interval from 0.067554mm, the eighth interval from 0.071943mm, and the ninth interval from 0.076332mm to 0.080721mm.

[0067] In Figure 6(c), the color values ​​corresponding to group C1 from bottom to top are as follows: the first interval from bottom to top: 0.028037mm to 0.033023mm; the second interval from bottom to top: 0.033023mm to 0.038009mm; the third interval from bottom to top: 0.038009mm to 0.042995mm; the fourth interval from bottom to top: 0.042995mm to 0.047982mm; and the fifth interval from bottom to top: ... The value range is from 0.047982mm to 0.052968mm. The color value range for the sixth interval is from 0.052968mm to 0.057954mm, for the seventh interval it is from 0.057954mm to 0.062940mm, for the eighth interval it is from 0.062940mm to 0.067926mm, and for the ninth interval it is from 0.067926mm to 0.072912mm.

[0068] In group C2, the color values ​​for the first interval from bottom to top correspond to a range of 0.033217mm to 0.035859mm; the second interval from 0.035859mm to 0.038502mm; the third interval from 0.038502mm to 0.041144mm; the fourth interval from 0.041144mm to 0.043786mm; and the fifth interval... The color values ​​for the sixth interval range from 0.043786mm to 0.046429mm; the values ​​for the seventh interval range from 0.049071mm to 0.051713mm; the values ​​for the eighth interval range from 0.051713mm to 0.054356mm; and the values ​​for the ninth interval range from 0.054356mm to 0.056998mm.

[0069] In group C3, the color values ​​corresponding to the first interval from bottom to top are 0.035645mm to 0.037203mm, the second interval is 0.037203mm to 0.038760mm, the third interval is 0.038760mm to 0.040318mm, the fourth interval is 0.040318mm to 0.041876mm, and the fifth interval is... The color values ​​for the sixth interval range from 0.041876mm to 0.043434mm, the seventh interval ranges from 0.044992mm, the eighth interval ranges from 0.046550mm, and the ninth interval ranges from 0.048107mm to 0.049665mm.

[0070] In group C4, the color values ​​for the first interval from bottom to top correspond to a range of 0.037662mm to 0.038762mm; the second interval corresponds to a range of 0.038762mm to 0.039862mm; the third interval corresponds to a range of 0.039862mm to 0.040962mm; the fourth interval corresponds to a range of 0.040962mm to 0.042062mm; and the fifth interval corresponds to a range of... The color values ​​for the sixth interval are 0.042062mm to 0.043162mm, the seventh interval is 0.044262mm to 0.045362mm, the eighth interval is 0.045362mm to 0.046462mm, and the ninth interval is 0.046462mm to 0.047562mm.

[0071] In group C5, the color values ​​for the first interval from bottom to top correspond to a range of 0.040621mm to 0.043418mm; the second interval from 0.043418mm to 0.046216mm; the third interval from 0.046216mm to 0.049013mm; the fourth interval from 0.049013mm to 0.051811mm; and the fifth interval... The color values ​​for the sixth interval range from 0.051811mm to 0.054608mm, the seventh interval ranges from 0.057406mm to 0.060202mm, the eighth interval ranges from 0.060202mm to 0.063000mm, and the ninth interval ranges from 0.063000mm to 0.065797mm.

[0072] In group C6, from bottom to top, the color values ​​for the first interval are 0.041789mm to 0.046536mm, the second interval is 0.046536mm to 0.051284mm, the third interval is 0.051284mm to 0.056032mm, the fourth interval is 0.056032mm to 0.060780mm, and the fifth interval is... The color values ​​for the sixth interval range from 0.060780mm to 0.065527mm; the values ​​for the seventh interval range from 0.070275mm to 0.075022mm; the values ​​for the eighth interval range from 0.075022mm to 0.079770mm; and the values ​​for the ninth interval range from 0.079770mm to 0.084517mm.

[0073] like Figures 6(a)-6(c)As shown, finite element analysis revealed that without auxiliary structures (control group A), the maxillary central incisors exhibited labial tilt centered on the middle third of the root, meaning crown movement was greater than root movement. With increasing thickness h of the root control structure, the center of rotation of the teeth shifted towards the occlusal direction, indicating increased root movement. However, at the same thickness, the root movement trend of the modified root control structure group (group C) was consistently better than that of the traditional root control structure group (group B). When the thickness h increased from 0.1 mm to 0.25 mm, the center of rotation gradually shifted towards the occlusal direction with increasing thickness. When h ≥ 0.3 mm, both the crown and root showed a tendency towards palatal movement, accompanied by an indentation tendency. Regarding periodontal ligament stress, stress in all groups was concentrated in the apical region and the labial cervical margin region. When the thickness of the root control structure reached 0.4 mm and 0.5 mm, additional stress concentration was observed in the mesial cervical margin region. Considering both the crown / root displacement ratio (C / R) and stress distribution, the modified root control structure with h = 0.25 mm exhibits the most ideal root control trend in the sagittal plane. That is, while producing a significant tendency for palatal root movement, it also exhibits minimal labial crown movement and a relatively reasonable stress distribution.

[0074] In the comparative example (control group) without any auxiliary structures, when the appliance was preset to 1° palatal root torque, the maxillary central incisors exhibited labial tilting movement centered on the middle third of the root. This means that tooth movement was dominated by undesirable labial crown movement, while the required palatal root movement was severely insufficient, resulting in poor torque control efficiency.

[0075] Both the traditional root control structure and the improved root control structure of this invention effectively improve the above-mentioned problems. As the thickness of the root control structure increases, the rotation center of the tooth moves towards the occlusal direction, indicating an increase in root movement and enhanced root control.

[0076] However, key comparative data show that, at the same thickness, the improved root control structure of this invention consistently outperforms the traditional root control structure in promoting root movement. Specifically, the improved root control structure group exhibits a more advantageous crown movement / root movement (C / R) ratio at the same thickness, indicating that it achieves more significant root movement and more effective root torque control.

[0077] like Figure 7(a)-7(e)As shown in Figure 7(a), the color values ​​in group A from bottom to top are as follows: the first interval from bottom to top: 0.000039541 to 0.0086212; the second interval from bottom to top: 0.0086212 to 0.017203; the third interval from bottom to top: 0.017203 to 0.025785; the fourth interval from bottom to top: 0.025785 to 0.034366; and the fifth interval... The color values ​​for the first interval range from 0.034366 to 0.042948, the sixth interval ranges from 0.042948 to 0.051530, the seventh interval ranges from 0.051530 to 0.060111, the eighth interval ranges from 0.060111 to 0.068693, and the ninth interval ranges from 0.068693 to 0.077275.

[0078] In Figure 7(b), the color values ​​in group B1, from bottom to top, range as follows: first interval: 0.0048873 to 0.012569; second interval: 0.012569 to 0.020250; third interval: 0.020250 to 0.027932; fourth interval: 0.027932 to 0.035613; fifth interval: 0.035613 to 0.043295; sixth interval: 0.043295 to 0.050976; seventh interval: 0.050976 to 0.058657; eighth interval: 0.058657 to 0.066339; and ninth interval: 0.066339 to 0.074020.

[0079] In Group B2, from bottom to top, the color values ​​for the first interval are 0.0051622 to 0.013938, the second interval is 0.013938 to 0.022714, the third interval is 0.022714 to 0.031491, the fourth interval is 0.031491 to 0.040267, the fifth interval is 0.040267 to 0.049043, the sixth interval is 0.049043 to 0.057819, the seventh interval is 0.057819 to 0.066595, the eighth interval is 0.066595 to 0.075371, and the ninth interval is 0.075371 to 0.084147.

[0080] In Group B3, from bottom to top, the color values ​​for the first interval are 0.0075906 to 0.016411, the second interval is 0.016411 to 0.025231, the third interval is 0.025231 to 0.034051, the fourth interval is 0.034051 to 0.042871, the fifth interval is 0.042871 to 0.051691, the sixth interval is 0.051691 to 0.060511, the seventh interval is 0.060511 to 0.069331, the eighth interval is 0.069331 to 0.078151, and the ninth interval is 0.078151 to 0.086971.

[0081] In Figure 7(c), the color values ​​in group B4, from bottom to top, range as follows: first interval: 0.0076409 to 0.016406; second interval: 0.016406 to 0.025170; third interval: 0.025170 to 0.033935; fourth interval: 0.033935 to 0.042700; fifth interval: 0.042700 to 0.051464; sixth interval: 0.051464 to 0.060229; seventh interval: 0.060229 to 0.068994; eighth interval: 0.068994 to 0.077759; and ninth interval: 0.077759 to 0.086523.

[0082] In group B5, from bottom to top, the color values ​​for the first interval are 0.0076662 to 0.017482, the second interval is 0.017482 to 0.027297, the third interval is 0.027297 to 0.037113, the fourth interval is 0.037113 to 0.046929, the fifth interval is 0.046929 to 0.056744, the sixth interval is 0.056744 to 0.066560, the seventh interval is 0.066560 to 0.076376, the eighth interval is 0.076376 to 0.086191, and the ninth interval is 0.086191 to 0.096007.

[0083] In Group B6, from bottom to top, the color values ​​for the first interval are 0.0073479 to 0.020431, the second interval is 0.020431 to 0.033514, the third interval is 0.033514 to 0.046598, the fourth interval is 0.046598 to 0.059681, the fifth interval is 0.059681 to 0.072764, the sixth interval is 0.072764 to 0.085847, the seventh interval is 0.085847 to 0.098931, the eighth interval is 0.098931 to 0.11201, and the ninth interval is 0.11201 to 0.12510.

[0084] In Figure 7(d), the color values ​​corresponding to the C1 group from bottom to top are as follows: the first interval from bottom to top: 0.0063623 to 0.012391; the second interval from bottom to top: 0.012391 to 0.020149; the third interval from bottom to top: 0.020149 to 0.027908; the fourth interval from bottom to top: 0.027908 to 0.035667; the fifth interval from bottom to top: 0.035667 to 0.043425; the sixth interval from bottom to top: 0.043425 to 0.051184; the seventh interval from bottom to top: 0.051184 to 0.058942; the eighth interval from bottom to top: 0.058942 to 0.066701; and the ninth interval from bottom to top: 0.066701 to 0.074459.

[0085] In Group C2, from bottom to top, the color values ​​for the first interval are 0.0051866 to 0.014002; the second interval is 0.014002 to 0.022818; the third interval is 0.022818 to 0.031634; the fourth interval is 0.031634 to 0.040449; the fifth interval is 0.040449 to 0.049265; the sixth interval is 0.049265 to 0.058081; the seventh interval is 0.058081 to 0.066896; the eighth interval is 0.066896 to 0.075712; and the ninth interval is 0.075712 to 0.084528.

[0086] The color values ​​for the C3 group, from bottom to top, are as follows: the first interval from 0.0015468 to 0.016413, the second interval from 0.016413 to 0.025278, the third interval from 0.025278 to 0.034142, the fourth interval from 0.034142 to 0.043007, the fifth interval from 0.043007 to 0.051871, the sixth interval from 0.051871 to 0.060736, the seventh interval from 0.060736 to 0.069600, the eighth interval from 0.069600 to 0.078465, and the ninth interval from 0.078465 to 0.087329.

[0087] In Figure 7(e), the color values ​​for the C4 group from bottom to top are as follows: the first interval from bottom to top: 0.0065114 to 0.015380; the second interval from bottom to top: 0.015380 to 0.024249; the third interval from bottom to top: 0.024249 to 0.033117; the fourth interval from bottom to top: 0.033117 to 0.041986; the fifth interval from bottom to top: 0.041986 to 0.050855; the sixth interval from bottom to top: 0.050855 to 0.059723; the seventh interval from bottom to top: 0.059723 to 0.068592; the eighth interval from bottom to top: 0.068592 to 0.077461; and the ninth interval from bottom to top: 0.077461 to 0.086329.

[0088] The color values ​​for the C5 group, from bottom to top, are as follows: the first interval from 0.0088698 to 0.019099, the second interval from 0.019099 to 0.029329, the third interval from 0.029329 to 0.039559, the fourth interval from 0.039559 to 0.049788, the fifth interval from 0.049788 to 0.060018, the sixth interval from 0.060018 to 0.070248, the seventh interval from 0.070248 to 0.080477, the eighth interval from 0.080477 to 0.090707, and the ninth interval from 0.090707 to 0.10094.

[0089] The color values ​​for the C6 group, from bottom to top, are as follows: the first interval from 0.0060743 to 0.021416, the second interval from 0.021416 to 0.035225, the third interval from 0.035225 to 0.049034, the fourth interval from 0.049034 to 0.062843, the fifth interval from 0.062843 to 0.076653, the sixth interval from 0.076653 to 0.090462, the seventh interval from 0.090462 to 0.10427, the eighth interval from 0.10427 to 0.11808, and the ninth interval from 0.11808 to 0.13189.

[0090] In this designation, La (Labial) represents the labial side, D (Distal) represents the distal side, P (Platal) represents the palatal side (lingual side), and M (Mesial) represents the mesial side. Through systematic analysis of the biomechanical response at different thicknesses (0.1 mm to 0.5 mm), it was found that when the thickness exceeded 0.3 mm, both the crown and root exhibited palatal movement with an indentation tendency. Comprehensive analysis of root control effectiveness and accompanying crown movement confirmed that a modified root control structure with a thickness of 0.25 mm was the optimal solution. At this thickness, it can promote palatal movement of the root while minimizing the accompanying labial movement of the crown, achieving the best sagittal plane control effect.

[0091] Stress analysis of the periodontal ligament showed that in all experimental groups, stress was mainly concentrated in the apical region and the labial cervical margin region, which is a typical stress distribution in torque control.

[0092] It is worth noting that when the thickness of the root control structure increased to 0.4 mm and 0.5 mm, additional stress concentration appeared in the mesial cervical margin region. This abnormal stress concentration may indicate a potential risk of root resorption. The preferred thickness of 0.25 mm in this invention achieves efficient root control while avoiding the occurrence of such high-risk stress concentration areas, indicating that it has higher biological safety.

[0093] Therefore, based on the above finite element analysis results and Figure 8It can be concluded that the improved root control structure (locally thickened structure) provided by this invention offers superior root torque control performance at the same thickness compared to the traditional root control structure (uniform thickness twisted structure). Furthermore, through parameter optimization, 0.25mm was determined as the optimal implementation thickness. This parameter ensures efficient root movement while maintaining a reasonable periodontal ligament stress level, thus achieving an optimal balance between therapeutic efficacy and safety.

[0094] These findings provide a biomechanical basis for the precise application of this invention in personalized clinical invisible orthodontic treatment programs.

[0095] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A clear aligner with a modified root control structure, characterized in that, Includes the clear aligner body and a modified root control structure; The modified root control structure is provided in at least one-third of the labial cervical region and one-third of the mesial proximal cervical region of a single anterior tooth, and / or in the distal cusp region. It is located on the inner surface of the cavity of the clear aligner body used to accommodate the tooth. The modified root control structure is a solid structure formed by locally thickening the clear aligner body relative to the inner surface of the cavity toward the tooth surface of the anterior tooth, and extends in at least one direction, namely mesiodistal and labiolingual. The modified root control structure has a length of 4 mm and a width of 1 mm. The thickness of the modified root control structure relative to the inner surface ranges from 0.1 mm to 0.5 mm. The anterior teeth are selected from at least one of incisors and canines.

2. The invisible orthodontic appliance with a modified root control structure according to claim 1, characterized in that, The invisible aligner body has at least one modified root control structure corresponding to a single anterior tooth.

3. The invisible orthodontic appliance with a modified root control structure according to claim 2, characterized in that, The modified root control structure is located at one-third of the mesial proximal cervical region of the canine and one-third of the distal cusp region of the canine, extending along the labial and lingual direction.

4. The invisible orthodontic appliance with a modified root control structure according to claim 1, characterized in that, The improved root control structure has a thickness increase of 0.25 mm relative to the inner surface.

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