Dental instrument and shell-shaped dental instrument

Abstract

The embodiment of the utility model provides a dental instrument and a shell-shaped dental instrument, the dental instrument comprises a shell-shaped body and a traction accessory which are integrally formed, the shell-shaped body is provided with a plurality of tooth storage cavities, the traction accessory is a prefabricated standard part, the standard part comprises a traction part, a traction rod and a base which are sequentially arranged, the cross section of the base is round, the shell-shaped body is provided with a base containing cavity, the base containing cavity is used for containing the base and a limiting part, the space between the base and the inner side wall of the base containing cavity is filled with the limiting part, and the limiting part is used for containing the base. The base is provided with a limiting part, the limiting part and the base are combined to form a mounting part, the outline of the inner surface of the base containing cavity is matched with the outline of the outer surface of the mounting part so that the traction accessory can be fixed to the shell-shaped body, and the cross section of the base containing cavity is in a non-circular shape.

Description

Technical Field

[0001] This application relates to the field of orthodontic technology, and in particular to a dental instrument and a shell-shaped dental instrument. Background Technology

[0002] Dental malocclusion includes problems such as crowded teeth, underbite, and misaligned teeth. The degree of malocclusion varies, and the difficulty of correction also varies. To achieve better orthodontic results, some dental malocclusions require the use of dental traction. Dental traction is actually a step in orthodontic treatment, which involves using a traction device to pull teeth that are growing in the wrong position back to their correct position.

[0003] Traction mainly includes intermaxillary traction, intramaxillary traction, and extramaxillary traction. Types of intermaxillary traction include: Class II traction, Class III traction, vertical traction, alternating traction, and oblique traction. Class II traction can promote the forward movement of the mandibular arch, affect the growth and development of the maxilla, elevate the mandibular molars and maxillary incisors, and promote clockwise rotation of the maxillary and mandibular planes. It primarily corrects the relationship between the Class II molars and reduces overbite. Class III traction mainly targets the teeth and dental arch, with a minor skeletal effect. It moves the mandibular teeth distally and the maxillary teeth mesially, promoting the forward development of the maxillary arch. It can also slightly inhibit the forward development of the mandibular arch, elevate the maxillary molars and mandibular incisors, and promote counterclockwise rotation of the maxillary and mandibular planes.

[0004] In existing invisible orthodontic technology, traction devices are often combined with invisible aligners to achieve the aforementioned traction. The traction device is fixed to the invisible aligner by adhesive or clip-on. However, the traction devices currently used are all common standard accessories. The base of the traction device is circular, and the cavity on the invisible aligner that cooperates with the traction device is also designed with a circular cross-section to match the shape of the traction device's base. In this case, because the traction device and the invisible aligner are restricted by the circular cross-section, rotational freedom is generated. That is to say, during the traction process, the traction accessory is prone to rotate relative to the invisible aligner, resulting in the inability to provide stable traction force during the orthodontic process.

[0005] Therefore, it is of great significance to provide a new type of traction device that can be stably installed on invisible aligners and can assist in the corresponding orthodontic functions. Utility Model Content

[0006] The purpose of this application is to provide a dental instrument and a shell-shaped dental instrument that can guide the correct installation of a traction device and limit the rotation of the traction device relative to the clear aligner, thereby providing a more stable traction force during the orthodontic process and improving the orthodontic effect.

[0007] To achieve the above objectives, embodiments of this application provide a dental instrument comprising an integrally formed shell-shaped body and a traction attachment. The shell-shaped body has multiple tooth receiving cavities, and the traction attachment is a prefabricated standard component. The standard component includes a traction part, a traction rod, and a base arranged sequentially. The base has a circular cross-sectional shape. The shell-shaped body has a base receiving cavity for accommodating the base and a limiting part. The limiting part fills the space between the base and the inner wall of the base receiving cavity. The limiting part and the base combine to form a mounting part. The inner surface contour of the base receiving cavity matches the outer surface contour of the mounting part to fix the traction attachment to the shell-shaped body. The cross-sectional shape of the base receiving cavity is non-circular.

[0008] Preferably, the shell-shaped body also has an accessory mounting platform, which is formed by a portion of the inner surface of the shell-shaped body protruding towards the distal tooth, and the base receiving cavity is composed of a portion of the accessory mounting platform.

[0009] Preferably, the base receiving cavity is a cavity enclosed by the inner surface of the accessory mounting platform, wherein the accessory mounting platform is provided with mounting holes, and the traction accessory passes through the mounting holes and is fixed to the shell-shaped body.

[0010] Preferably, the traction accessory further includes a retaining portion located between the traction rod and the base, wherein during assembly, the retaining portion contacts the outer surface of the accessory mounting platform.

[0011] Preferably, the base receiving cavity is formed by a portion of the outer surface of the accessory mounting platform being recessed towards the teeth, and the mounting portion is fixed to the base receiving cavity by adhesive bonding.

[0012] Preferably, the limiting portion is formed by filling the space between the base and the inner wall of the receiving cavity with adhesive and then curing it by light.

[0013] Preferably, the limiting part is an elastic rubber ring sleeved on the base. During assembly, the elastic rubber ring is in contact with the inner wall of the base receiving cavity and undergoes elastic deformation.

[0014] Preferably, the projection of the base onto the first plane is the inscribed circle of the projection of the base receiving cavity onto the first plane, wherein the first plane is perpendicular to the major axis of the traction attachment.

[0015] Preferably, the base receiving cavity has a pointing structure that indicates the installation direction of the traction attachment.

[0016] Preferably, the limiting portion is filled in the pointing structure.

[0017] Another embodiment of this application provides a shell-shaped dental instrument, including a shell-shaped body as described above.

[0018] Preferably, when worn, the inner surface of the base cavity on the shell-shaped body is spaced apart from the corresponding tooth.

[0019] Preferably, the base receiving cavity on the shell-like body is located on the buccal side and / or lingual side of the tooth receiving cavity.

[0020] The dental instruments and shell-shaped dental instruments provided by this utility model have at least the following advantages compared with the prior art:

[0021] The purpose of this technology is to improve the problem of relative rotation between the traction device and the existing clear aligner after assembly. The shell-like body of this application has a base housing cavity for the traction attachment. The cross-sectional shape of the base housing cavity is non-circular. A limiting part connects to the base to form a mounting part. The limiting part fills the space between the base of the traction attachment and the inner wall of the base housing cavity. Furthermore, the inner surface contour of the base housing cavity matches the outer surface contour of the mounting part; that is, the cross-sectional shape of the mounting part is consistent with the cross-sectional shape of the base housing cavity. This design creates a constraint between the mounting part and the base housing cavity, preventing relative rotation during use and ensuring the stability of the traction force during treatment, thereby improving the treatment effect.

[0022] In addition, in some embodiments of this application, the base receiving cavity has a pointing structure that indicates the installation direction of the traction attachment. When it is necessary to directionally install the traction attachment, the pointing structure can indicate the installation direction of the traction attachment to the operator. Attached Figure Description

[0023] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0024] Figure 1 This is a schematic diagram of the dental instrument in Embodiment 1 of this application;

[0025] Figure 2 yes Figure 1 A magnified view of a portion of region A in the middle;

[0026] Figure 3 This is a schematic diagram of the cross-sectional shape of some of the base receiving cavities in Embodiment 1 of this application;

[0027] Figure 4 A schematic diagram of the structure of a dental instrument in Embodiment 1 of this application;

[0028] Figure 5 A schematic diagram of the structure of another dental instrument in Embodiment 1 of this application;

[0029] Figure 6 This is a schematic diagram of the structure of a traction attachment in Embodiment 1 of this application;

[0030] Figure 7 This is a schematic diagram of another traction attachment in Embodiment 1 of this application;

[0031] Figure 8 This is a schematic diagram of the structure of another dental instrument in Embodiment 1 of this application;

[0032] Figure 9 This is a partially enlarged schematic diagram of a dental instrument according to Embodiment 1 of this application;

[0033] Figure 10 yes Figure 9 A schematic diagram of the projection of the middle base, the limiting part, and the base receiving cavity on the first plane;

[0034] Figure 11 This is a cross-sectional schematic diagram of a base receiving cavity according to Embodiment 1 of this application;

[0035] Figure 12 A schematic diagram of the structure of a shell-like body in Embodiment 1 of this application;

[0036] Figure 13 This is a schematic diagram of the structure of a dental instrument according to Embodiment 2 of this application;

[0037] Figure 14 This is a schematic diagram of the structure of a shell-shaped dental instrument according to Embodiment 3 of this application;

[0038] Figure 15 This is a schematic diagram of another type of shell-shaped dental instrument in Embodiment 3 of this application. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of this application to enable readers to better understand this application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in this application can be implemented. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0040] Shell-type orthodontic appliances are invisible and aesthetically pleasing mechanical devices for teeth straightening, designed and manufactured using computer-aided 3D modeling. They are typically worn on the teeth and are made of polymer materials such as TPU, PETG, or a combination of both. These appliances exert forces that cause changes in the malocclusion of the jawbone, misaligned teeth, and periodontal tissues, promoting normal dentofacial growth and development. Shell-type appliances utilize biomechanical principles to correct malocclusion. Through a system consisting of a series of shell-type appliances, gentle and sustained biomechanical forces are applied to gradually move the teeth back to their correct positions and align them properly. During treatment, additional attachments or unique structures are often incorporated into the shell-type appliances to apply extra corrective forces to the teeth.

[0041] Shell-shaped orthodontic appliances have several cavities to accommodate multiple teeth, and are divided into lingual and labial surfaces, as well as mesial and distal surfaces. The term "lingual surface" is based on the nomenclature of the crown surfaces in the 2nd edition of *Introduction to Stomatology*, published by Peking University Medical Press, on pages 35-36. The labial and buccal surfaces are the surfaces of the crowns of anterior teeth that are closest to the lips, while the buccal surfaces are the surfaces of the crowns of posterior teeth that are closest to the buccal area. The lingual surface is the surface of the crowns of both anterior and posterior teeth that is closest to the tongue. The mesial and distal surfaces are the two surfaces of the crown that meet adjacent teeth, collectively called the proximal surfaces. The end closer to the facial midline is called the mesial end, and the end farther from the facial midline is called the distal end.

[0042] One technical solution protected in this application is a dental instrument and a shell-shaped dental instrument. The main issue is that in existing technologies, standardized traction attachments lack a limiting mechanism between the attachment and the shell-shaped body. During traction, relative rotation occurs between the attachment and the shell-shaped body, affecting the stability of traction and further impacting the orthodontic effect. Therefore, the technical problem this application aims to solve is how to limit the rotation of the traction attachment during use by utilizing a customized shell-shaped body in conjunction with the traction attachment through structural design, while maintaining the advantages of standardized production of traction attachments, such as reduced costs and improved interchangeability. The dental instrument protected in this application includes a one-piece molded shell-shaped body and a traction attachment. The shell-shaped body has multiple tooth receiving cavities, and the traction attachment is a prefabricated standard component. The standard component includes a traction part, a traction rod, and a base arranged sequentially. The base has a circular cross-sectional shape. The shell-shaped body has a base receiving cavity for accommodating the base and a limiting part. The limiting part fills the space between the base and the inner wall of the base receiving cavity. The limiting part and the base combine to form a mounting part. The inner surface contour of the base receiving cavity matches the outer surface contour of the mounting part to fix the traction attachment to the shell-shaped body. The cross-sectional shape of the base receiving cavity is non-circular. The cross-sectional shape of the mounting part is consistent with the cross-sectional shape of the base receiving cavity. In this way, a constraint can be formed between the mounting part and the base receiving cavity, preventing relative rotation between them during use, ensuring the stability of the traction force during orthodontic treatment, thereby improving the orthodontic effect.

[0043] The various embodiments of this application will now be described with reference to the accompanying drawings. Example

[0044] join Figure 1 and Figure 2As shown, this embodiment provides a dental instrument, including an integrally formed shell-shaped body 1 and a traction attachment 2. The shell-shaped body 1 has multiple tooth receiving cavities 11, which may cover all teeth on the jaw or only some teeth, depending on the orthodontic needs. In some cases, at least some of the tooth receiving cavities 11 in the shell-shaped body 1 can have a teeth-correcting function, applying orthodontic forces to the teeth through elastic deformation. The traction attachment 2 is a prefabricated standard component, which includes a traction part 21, a traction rod 22, and a base 23 arranged sequentially. The base 23 has a circular cross-sectional shape. The shell-shaped body 1 has a base receiving cavity 13, which is used to accommodate the base 23 and the limiting part 3. The limiting part 3 fills the space between the base 23 and the inner wall of the base receiving cavity 13. The limiting part 3 is connected to the base 23 to form a mounting part. The inner surface contour of the base receiving cavity 13 matches the outer surface contour of the mounting part to fix the traction attachment 2 to the shell-shaped body 1. The cross-sectional shape of the base receiving cavity 13 is not circular. (See details below.) Figure 3 Figures (a) to (f) show some cross-sectional shapes of the base receiving cavity 13, which can be rectangular, teardrop, triangular or other irregular shapes.

[0045] Specifically, the shell-shaped body 1 has an accessory mounting platform 12, which is formed by a portion of the inner surface of the shell-shaped body 1 protruding in the distal direction. The base receiving cavity 13 is composed of a portion of the accessory mounting platform 12. In this embodiment, reference is made to... Figure 4 and Figure 5 As shown, the base receiving cavity 13 is a cavity formed by the inner surface of the accessory mounting platform 12. The accessory mounting platform 12 is provided with mounting holes 14. The traction accessory 2 passes through the mounting holes 14 and is fixed to the shell-shaped body 1.

[0046] In this embodiment, the limiting part 3 can be formed by filling the space between the base 23 and the inner wall of the receiving cavity with an adhesive and then curing it by light. The adhesive is a flowing resin (3M ESPE Filtek Flow), and the limiting part 3 is formed by light curing. The specific manufacturing process is as follows: first, a shell-shaped body 1 with an accessory mounting platform 12 is obtained by hot pressing or direct 3D printing. The base 23 of the traction accessory 2 is installed in the base receiving cavity 13. The flowing resin is filled into the gap between the base 23 and the base receiving cavity 13. The flowing resin is cured by light curing to form a mounting part with the base 23. The overall shape of the mounting part is consistent with the shape of the base receiving cavity 13. In this way, the flowing resin can cure quickly, reduce waiting time, improve clinical efficiency, and at the same time ensure uniform filling, reduce gaps, and improve the overall structure. Meanwhile, both the mounting part and the base receiving cavity 13 have non-circular cross-sections, preventing relative rotation and improving the stability of the traction attachment 2. Even if the cured resin loses its adhesiveness to the base receiving cavity 13, the mounting part and the base receiving cavity 13 can still abut against each other, preventing rotation of the traction attachment 2. In another case, the limiting part 3 can be an elastic rubber ring fitted onto the base 23. During assembly, the elastic rubber ring adheres to the inner wall of the base receiving cavity 13 and undergoes elastic deformation. The elastic deformation of the elastic rubber ring generates a preload force, which can better fix the base 23 of the traction attachment 2 in the base receiving cavity 13. The elastic rubber ring can be a three-layer composite rubber ring with an inner layer of 50A silicone, a middle layer of 70A fluororubber, and an outer layer of 90A polyurethane. During assembly, the compression rate is controlled at 15% to 25%, generating a continuous normal preload force Fn = 1.2-1.8N. Furthermore, the volume change rate of the fluororubber outer layer after soaking in artificial saliva for 30 days is <0.5%, resulting in a long service life.

[0047] In some embodiments, the traction attachment 2 can be integrally formed or a separate structure. (See reference) Figure 6 and Figure 7 As shown, the traction accessory 2 is a split structure, including a functional part 2a with a traction unit 21 and a traction rod 22, and a fixing part 2b including a base 23. The functional part 2a and the fixing part 2b are installed together by snap-fit ​​or threaded connection. (Reference) Figure 4As shown, the traction attachment 2 is an integral structure. When assembling the traction attachment 2 with the shell-shaped body 1, it can be installed from the outside in (the X direction in the figure is the installation direction of the traction attachment 2). In this case, the size of the base 23 is slightly smaller than the size of the mounting hole 14, or the size of the base 23 is slightly larger than the size of the mounting hole 14. During assembly, the mounting hole 14 undergoes a certain elastic deformation to allow the base 23 to pass through. The size of the traction part 21 is larger than the size of the mounting hole 14. After the base 23 enters the base receiving cavity 13 from the outside, it is fixed to the base receiving cavity 13 by applying flowing resin or by wearing an elastic rubber ring. In another case, refer to... Figure 5 As shown, when the traction attachment 2 is assembled with the shell-shaped body 1, it can be installed from the inside out (the Y direction in the figure is the installation direction of the traction attachment 2). In this case, the size of the traction part 21 is slightly smaller than the size of the mounting hole 14, or the size of the traction part 21 is slightly larger than the size of the mounting hole 14. During assembly, the mounting hole 14 undergoes a certain elastic deformation to allow the traction part 21 to pass through. The size of the base 23 is larger than the size of the mounting hole 14. The traction part 21 passes through the mounting hole 14, and the base 23 remains in the base receiving cavity 13. Then, it is fixed to the base receiving cavity 13 by applying flowing resin or by wearing an elastic rubber ring.

[0048] In some implementations, reference Figure 8 As shown, the traction attachment 2 also includes a retaining part 24 located between the traction rod 22 and the base 23. During assembly, the retaining part 24 contacts the outer surface of the attachment mounting platform 12. The size of the retaining part 24 is larger than the size of the mounting hole 14, and the distance between the retaining part 24 and the base 23 is equal to the thickness of the shell-shaped body 1. After assembly, it can restrict the movement of the traction attachment 2 along the attachment axis, ensuring that the traction attachment 2 will not change position during traction. More preferably, in order to further stabilize the position of the traction attachment 2 on the shell-shaped body 1 after assembly, a metal shim can be added between the base 23 and the shell-shaped body 1, thereby increasing the preload between the base 23 and the shell-shaped body 1.

[0049] In some implementations, reference Figure 9 As shown, the projection of the base 23 onto the first plane M is the inscribed circle of the projection of the base receiving cavity 13 onto the first plane M, wherein the first plane M is perpendicular to the major axis direction Z of the traction attachment 2. This design not only optimizes the dimensions of the attachment mounting platform 12 and ensures the wrapping force of the shell-shaped body 1 on the teeth, but also enables precise alignment of the base 23 and the base receiving cavity 13 during installation, reducing installation errors. A specific embodiment is described below. Figure 10As shown, the projection of the accessory base receiving cavity 13 on the first plane M is approximately a square B, and the projection of the base 23 on the first plane M is the inscribed circle C of the square. In this case, flowing resin is preferred as the limiting part 3. The flowing resin can better fill the corner positions between the base receiving cavity 13 and the base 23, thereby fixing the traction accessory 2 on the shell-shaped body 1.

[0050] In some embodiments, the base receiving cavity 13 has a pointing structure 131 that indicates the installation direction of the traction attachment 2. Especially for the traction unit 21, which requires limiting the traction direction, the pointing structure 131 can better guide the operator during clinical installation, ensuring that the direction of the traction force provided by the traction attachment 2 after installation is consistent with the direction in the treatment plan, avoiding incorrect installation, improving ease of use and safety, and reducing the risk of operational errors. (Reference) Figure 11 The schematic cross-sectional view of the base housing cavity 13 shown indicates that the pointing structure 131 can be arrow-shaped or other visual structure that clearly indicates a unique direction. For example, one possible implementation is described in reference to... Figure 12 As shown, the pointing direction P is consistent with the traction direction, and the bending direction of the traction part 21 is (e.g.) Figure 6 The direction of the center (Q) and the direction of the pointing (P) are the same. During installation, the bending direction of the traction part 21 is aligned with the pointing direction (P) of the pointing structure 131.

[0051] In some embodiments, the limiting portion 3 fills the pointing structure 131. In this case, the shape of the non-pointing structure 131 portion of the base receiving cavity 13 can be designed to be circular, consistent with the shape of the base 23. This optimizes the dimensions of the accessory mounting platform 12, ensures the enveloping force of the shell-like body 1 on the teeth, and enables precise alignment of the base 23 and the base receiving cavity 13 during installation, reducing installation errors. Furthermore, in this embodiment, the limiting portion 3 is preferably made of flowing resin, which can better fill the pointing structure 131, thus securing the traction accessory 2 to the shell-like body 1. Example

[0052] refer to Figure 13As shown, the main difference between this embodiment and Embodiment 1 is that in this embodiment, the traction attachment 2 is integrally fixed to the outer surface of the shell-shaped body 1, and the base receiving cavity 13 is formed by a portion of the outer surface of the attachment mounting platform 12 recessed towards the teeth. The mounting part is fixed in the base receiving cavity 13 by adhesive bonding. The base receiving cavity 13 is a semi-closed cavity, and has an opening structure 15 facing the distal tooth direction for mounting the traction attachment 2. The size of the opening structure 15 is smaller than the size of the base 23 of the traction attachment 2. During assembly, the opening structure 15 undergoes a certain elastic deformation, allowing the base 23 of the traction attachment 2 to enter the base receiving cavity 13. Furthermore, after assembly, the opening structure can restrict the movement of the traction attachment 2 along its long axis.

[0053] In this embodiment, the limiting part 3 is formed by filling the space between the base 23 and the inner wall of the receiving cavity with adhesive and then curing it by light. Specifically, during assembly, the base 23 of the traction accessory 2 can be coated with a flowing resin, then inserted into the base receiving cavity 13 and light-cured to form the limiting part 3. Alternatively, the flowing resin can be coated into the base receiving cavity 13 first, then the base 23 of the traction accessory 2 can be placed into the base receiving cavity 13, and then light-cured to form the limiting part 3.

[0054] The advantage of this embodiment compared to embodiment one is that it does not damage the integrity of the shell-shaped body 1, allowing the orthodontic force generated by the elastic deformation of the appliance to be applied to the teeth more effectively. Example

[0055] This third embodiment provides a shell-shaped dental instrument, including a shell-shaped body 1 as in Embodiment 1 or Embodiment 2. To avoid the impact on orthodontics caused by contact between the base receiving cavity 13 and the tooth during traction, the inner surface of the base receiving cavity 13 on the shell-shaped body 1 is spaced apart from the corresponding tooth 4. This is particularly evident in the design of the base receiving cavity 13 on the shell-shaped body 1 in Embodiment 2, as described in reference [reference needed]. Figure 14 As shown, the base receiving cavity 13 is formed by a portion of the outer surface of the accessory mounting platform 12 being recessed towards the tooth, and the inner surface of the base receiving cavity 13 is set with a gap H with the corresponding tooth 4.

[0056] In some embodiments, the base receiving cavity 13 on the shell-like body 1 is located on the buccal and / or lingual side of the tooth receiving cavity 11. Furthermore, referring to… Figure 1 As shown, the base housing 13 can be located on the tooth receiving cavity 11 of the shell-shaped body 1, depending on the orthodontic needs. In other cases, when the traction point is located at the gingiva, refer to... Figure 15 As shown, the shell-shaped body 1 can extend to cover the gum line, and the base receiving cavity 13 is disposed in the area of ​​the shell-shaped body 1 corresponding to the gum line.

[0057] It should be noted that the above embodiments can be freely combined as needed to form different new implementation schemes without causing contradictions. All implementation schemes formed by such combinations are within the protection scope of this utility model. In order to save space in the application text, they will not be described in detail here.

[0058] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

[0059] Similarly, the above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A dental instrument comprising an integrally molded shell-like body and a traction attachment, the shell-like body having multiple tooth receiving cavities, and the traction attachment being a prefabricated standard part, wherein, The standard component includes a traction part, a traction rod, and a base arranged sequentially. The base has a circular cross-sectional shape. The shell-like body has a base receiving cavity for accommodating the base and a limiting part. The limiting part fills the space between the base and the inner wall of the base receiving cavity. The limiting part and the base combine to form a mounting part. The inner surface contour of the base receiving cavity matches the outer surface contour of the mounting part to fix the traction accessory to the shell-like body. The cross-sectional shape of the base receiving cavity is non-circular.

2. The dental instrument according to claim 1, characterized in that, The shell-shaped body also has an accessory mounting platform, which is formed by a portion of the inner surface of the shell-shaped body protruding towards the distal tooth, and the base receiving cavity is composed of a portion of the accessory mounting platform.

3. The dental instrument according to claim 2, characterized in that, The base receiving cavity is a cavity enclosed by the inner surface of the accessory mounting platform. The accessory mounting platform is provided with mounting holes, and the traction accessory passes through the mounting holes and is fixed to the shell-shaped body.

4. The dental instrument according to claim 3, characterized in that, The traction accessory also includes a retaining part located between the traction rod and the base, which contacts the outer surface of the accessory mounting platform during assembly.

5. The dental instrument according to claim 2, characterized in that, The base receiving cavity is formed by a portion of the outer surface of the accessory mounting platform being recessed towards the teeth, and the mounting part is fixed to the base receiving cavity by adhesive bonding.

6. The dental instrument according to claim 1 or 5, characterized in that, The limiting portion is formed by filling the space between the base and the inner wall of the receiving cavity with adhesive.

7. The dental instrument according to claim 3, characterized in that, The limiting part is an elastic rubber ring sleeved on the base. During assembly, the elastic rubber ring is in contact with the inner wall of the base cavity and undergoes elastic deformation.

8. The dental instrument according to claim 1 or 5, characterized in that, The projection of the base onto the first plane is the inscribed circle of the projection of the base receiving cavity onto the first plane, wherein the first plane is perpendicular to the major axis of the traction attachment.

9. The dental instrument according to claim 1 or 5, characterized in that, The base housing cavity has a pointing structure that indicates the installation direction of the traction attachment.

10. The dental instrument according to claim 9, characterized in that, The limiting part is filled in the pointing structure.

11. A shell-shaped dental instrument, characterized in that, Includes the shell-like body as described in claims 1-10.

12. The shell-shaped dental instrument according to claim 11, characterized in that, The base housing cavity on the shell-like body is located on the buccal side and / or lingual side of the tooth receiving cavity.

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