Traction accessory and dental instrument

Abstract

The embodiment of the utility model provides a traction accessory and a dental instrument, the traction accessory is used for dental orthodontic correction, the traction accessory comprises a limiting part, a traction rod and a base which are sequentially connected, the limiting part comprises a first free end extending towards a first direction and a second free end extending towards a second direction, the first direction and the second direction do not coincide; a limiting groove for containing a traction piece is formed in the connecting position between the limiting part and the traction rod, and the traction rod comprises a top face connected with the limiting part. The projection of the outline edge of a part of the limiting part on a first plane is located in a projection area of the top surface on the first plane, and the projection of the first free end and the projection of the second free end on the first plane are both located outside the projection area of the top surface on the first plane, the first plane is parallel to the cross section of the draw bar.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of oral orthodontic technology, and in particular to a traction attachment and a dental instrument. Background Art

[0002] In clinical orthodontic treatment in dentistry, functional accessories are sometimes used to enhance the correction effect. Common functional accessories include traction accessories, which are used to suspend traction parts so that the traction force acts on the corresponding parts. Traction accessories are used in a variety of application scenarios, such as anterior tooth depression, tooth elongation, space adjustment, eruption traction, tooth twisting, etc., all of which require the use of traction accessories for auxiliary treatment.

[0003] In the prior art, the traction attachment can be fixed on the tooth surface or fixed on an invisible shell-shaped orthodontic appliance, and is used in conjunction with a rubber band (traction member) to correct teeth. Generally, the traction attachment includes a base for bonding, a traction rod for hanging the rubber band, and a head for limiting the detachment of the rubber band, and a limiting groove for limiting the rubber band is formed between the head and the traction rod. However, when the traction force of the rubber band is not perpendicular to the traction rod (for example, the side of the tooth where the traction attachment is located is severely tilted, or the traction members hanging at both ends of the rubber band are misaligned in the distal tooth direction, so that the entire rubber band is not on the same plane), the protruding structure of the head of the traction attachment will limit the rubber band, making it impossible for the rubber band to be stuck in the limiting groove. In this case, the closed-loop rubber band will gradually slide in the opposite direction of the traction force of the rubber band, causing the rubber band to slip, affecting the normal progress of orthodontic treatment, and even causing accidental swallowing, creating medical risks.

[0004] Therefore, it is of great significance to improve the structure of the existing traction accessories so that the traction member can be stably fixed in the limiting groove to prevent the traction member from falling off during the correction process. Utility Model Content

[0005] The purpose of the embodiments of the present application is to provide a traction accessory and a dental instrument that effectively solve the above-mentioned problems. It can solve the problem in the prior art that the traction member is blocked by the head of the traction member during the traction process, causing the closed-loop rubber ring to gradually slide in the opposite direction of the traction force of the rubber ring and finally slip off the traction member, so that the traction member is stably fixed in the limiting groove and the traction force can be effectively applied to the teeth.

[0006] To achieve the above-mentioned objectives, an embodiment of the present application provides a traction accessory for dental orthodontic correction, the traction accessory including a limiting portion, a traction rod and a base connected in sequence, the limiting portion including a first free end extending in a first direction and a second free end extending in a second direction, the first direction and the second direction do not overlap; a limiting groove for accommodating a traction member is formed at a connection position between the limiting portion and the traction rod, the traction rod including a top surface connected to the limiting portion; a projection of a contour edge of part of the limiting portion on the first plane is located within a projection area of ​​the top surface on the first plane, and the projections of the first free end and the second free end on the first plane are both located outside the projection area of ​​the top surface on the first plane, wherein the first plane is parallel to the cross-section of the traction rod.

[0007] Preferably, the angle between the first direction and the second direction is greater than 90° and less than or equal to 180°.

[0008] Preferably, the first direction and the second direction do not coincide with the traction direction.

[0009] Preferably, the limiting portion further includes a first side surface and a second side surface that are oppositely arranged, and at least one of the first side surface and the second side surface is a curved surface.

[0010] Preferably, when both the first side surface and the second side surface are curved surfaces, the curvature directions of the first side surface and the second side surface are consistent.

[0011] Preferably, when one of the first side surface and the second side surface is a curved surface, the other side surface is a flat surface.

[0012] Preferably, the first side surface and the second side surface are both arc surfaces, and the center of the circle where the projection of the first side surface on the first plane lies coincides with the center of the circle where the projection of the second side surface on the first plane lies.

[0013] Preferably, the first free end and the second free end are respectively bent toward the base.

[0014] Preferably, the surface of the limiting portion adjacent to the traction rod includes a concave curved surface and / or an inclined plane.

[0015] Preferably, when the surface of the limiting portion adjacent to the traction rod includes the inclined plane, the angle between the inclined plane and the long axis of the traction rod is greater than or equal to 30° and less than 90°; when the surface of the limiting portion adjacent to the traction rod includes the concave curved surface, the angle between the tangent of the highest point on the concave curved surface and the long axis of the traction rod is greater than or equal to 30° and less than 90°.

[0016] Preferably, the side wall of the traction rod is provided with a through hole structure for passing an arch wire and penetrating the side wall of the traction rod.

[0017] Preferably, there is an angle difference between the axial direction of the through-hole structure and the traction direction.

[0018] The present application also provides another embodiment including a dental instrument, comprising a shell-shaped body having multiple tooth receiving cavities and a traction accessory as described in any one of the above items, wherein the outer surface of the shell-shaped body has a mounting area for the traction accessory, and the traction accessory is fixed to the mounting area through a base.

[0019] Preferably, the installation area has a mounting platform protruding toward the distal tooth direction, and the base is fixed on the mounting platform in a predetermined posture.

[0020] Preferably, the mounting platform has a first protruding structure, and the base has a first concave structure that cooperates with the first protruding structure along a predetermined direction; or, the mounting platform has a second concave structure, and the base has a second protruding structure that cooperates with the second concave structure along a predetermined direction.

[0021] Preferably, the mounting surface profile of the mounting platform substantially matches the bottom surface profile of the base, and the mounting surface is generally flat or curved.

[0022] The traction attachment and dental instrument provided by the present invention have the following beneficial effects compared with the prior art:

[0023] The traction attachment in the present application has free ends extending in two directions respectively for limiting the traction member during the traction process, and the projection of the contour edge of part of the limiting portion on the first plane parallel to the cross section of the traction rod is located in the projection area of ​​the top surface on the first plane, so that during the traction process, the traction member will not be blocked by the edge of the limiting portion at this part of the limiting portion, thereby preventing the closed-loop traction member from gradually sliding in the opposite direction of the traction force, and the traction member can always be stably maintained in the limiting groove between the limiting portion and the traction rod, thereby improving the positioning effect of the traction member, so that the traction member can be stably maintained in the limiting groove during the traction process without slipping.

[0024] Other embodiments of the present application also include a dental instrument, in which the shell-shaped body has an installation area for installing a traction accessory, and has a mounting platform protruding toward the distal tooth direction. The raised mounting platform can be set to protrude in different directions according to traction requirements, so that the traction accessory can be fixed on the mounting platform in a predetermined position, which is suitable for various traction methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0026] Figure 1 It is a structural diagram of a traction accessory in the prior art;

[0027] Figure 2 yes Figure 1 A schematic top view of a traction attachment in the prior art;

[0028] Figure 3 is a schematic structural diagram of a traction accessory in some embodiments of the present application;

[0029] Figure 4 yes Figure 3 A schematic structural diagram of the embodiment in another perspective;

[0030] Figure 5 yes Figure 4 A schematic diagram of the projection of the limiting portion and the traction rod on the first plane from the viewing angle;

[0031] Figure 6 yes Figure 3 A schematic structural diagram of the embodiment in another perspective;

[0032] Figure 7 yes Figure 6 Schematic diagram of the assembled traction attachment and traction part from the perspective;

[0033] Figure 8 yes Figure 3 A schematic structural diagram of the embodiment in another perspective;

[0034] Figure 9 yes Figure 8 Schematic diagram of the assembled traction attachment and traction part from the perspective;

[0035] Figure 10 is a schematic structural diagram of a traction attachment in some other embodiments of the present application;

[0036] Figure 11 is a schematic structural diagram of a traction attachment in some other embodiments of the present application;

[0037] Figure 12 is a schematic structural diagram of a traction attachment in some other embodiments of the present application;

[0038] Figure 13 is a schematic diagram of the assembled traction accessory and traction member in other embodiments of the present application;

[0039] Figure 14 is a schematic structural diagram of a traction attachment in some other embodiments of the present application;

[0040] Figure 15 is a schematic structural diagram of a traction attachment in some other embodiments of the present application;

[0041] Figure 16 is a schematic structural diagram of a traction attachment in some other embodiments of the present application;

[0042] Figure 17 yes Figure 16 A schematic diagram of the corresponding relationship between the circle where the first side surface is located and the circle where the second side surface is located in the embodiment;

[0043] Figure 18 is a schematic structural diagram of a traction attachment in some other embodiments of the present application;

[0044] Figure 19 is a schematic structural diagram of a traction attachment in some other embodiments of the present application;

[0045] Figure 20 is a schematic structural diagram of a traction attachment in some other embodiments of the present application;

[0046] Figure 21 is a schematic structural diagram of a dental apparatus in some embodiments of the present application;

[0047] Figure 22 is a schematic structural diagram of dental instruments in other embodiments of the present application;

[0048] Figure 23 yes Figure 22 A partial enlarged schematic diagram of area A in the middle. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, each embodiment of the present application will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in each embodiment of the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present application. The various embodiments can be combined with each other and referenced to each other under the premise of no contradiction.

[0050] In the prior art, reference Figure 1 and Figure 2 As shown, the head 200 of the traction attachment 100 is often designed to be a mushroom shape that bulges outward on all sides. However, when the traction force of the rubber band 400 is not perpendicular to the traction rod (for example, the side of the tooth where the traction attachment is located is severely tilted, or the traction parts hanging at both ends of the rubber band are misaligned in the distal tooth direction, so that the entire rubber band is not on the same plane), the protruding structure of the head 200 of the traction attachment 100 will restrict the rubber band 400, so that the rubber band 400 cannot be stuck in the limiting groove 300, but is located in the area of ​​the traction rod close to the base. In this case, the closed-loop rubber band 400 will gradually slide in the opposite direction of the traction force of the rubber band 400 when subjected to traction, causing the rubber band 400 to slip, affecting the normal progress of orthodontic treatment, and may even cause accidental swallowing, creating medical risks.

[0051] The limiting portion of the traction accessory in each embodiment of the present application is specially designed. The edge of some limiting portions does not extend outward beyond the traction rod, so that the traction member will not be blocked by the edge of the limiting portion at this position, thereby preventing the closed-loop traction member from gradually sliding in the opposite direction of the traction force. The traction member can always be stably maintained in the limiting groove between the limiting portion and the traction rod, thereby improving the positioning effect of the traction member, so that the traction member can be stably maintained in the limiting groove during the traction process without slipping.

[0052] The various embodiments of this application are described below with reference to the accompanying drawings.

[0053] refer to Figures 3 to 9As shown, a traction accessory 1 is used for dental orthodontic correction, and the traction accessory 1 includes a limiting portion 11, a traction rod 12 and a base 13 that are connected in sequence, and the traction accessory 1 is an integrated structure, that is, the limiting portion 11, the traction rod 12 and the base 13 are all fixedly connected, or the traction accessory 1 is a split structure, that is, any two connected parts of the limiting portion 11, the traction rod 12 and the base 13 are detachably connected. The limiting portion 11 includes a first free end 111 extending in a first direction X1 and a second free end 112 extending in a second direction X2, and the first direction X1 and the second direction X2 do not overlap; a limiting groove 14 for accommodating the traction member 2 is formed at the connection position between the limiting portion 11 and the traction rod 12, and the traction rod 12 includes a top surface 121 connected to the limiting portion 11. Reference Figure 4 and Figure 5 As shown, the projection of the contour edge 11a of the partial limiting portion 11 on the first plane M is located within the projection area of ​​the top surface 121 on the first plane M, and the projections of the first free end 111 and the second free end 112 on the first plane M are both located outside the projection area of ​​the top surface 121 on the first plane M, wherein the first plane M is parallel to the cross-section of the traction rod 12.

[0054] Specifically, the projection of the contour edge 11a of part of the limiting portion 11 on the first plane M in various embodiments of the present application is located in the projection area of ​​the top surface 121 on the first plane M, including Figure 5 As shown in FIG, the projection of the contour edge 11a of the part of the limiting portion 11 on the first plane M is located in the projection area of ​​the top surface 121 on the first plane M, that is, with reference to FIG. Figure 6 As shown, in the side view of the traction accessory 1, in direction A, there is a distance difference H between a side edge 11a of the limiting portion 11 and the same side edge 12a of the traction rod 12. Of course, the projection of the contour edge 11a of the limiting portion 11 on the first plane M is partially located within the projection area of ​​the top surface 121 on the first plane M. This also includes the case where the projection of the contour edge 11a of the limiting portion 11 on the first plane M coincides with or is tangent to the projection of the edge of the top surface 121 on the first plane M. That is, the distance difference between the contour edge of the limiting portion 11 and the corresponding edge of the top surface 121 in the side view of the traction accessory 1 is zero. The advantage of this design is that it reduces the undercut area of ​​the traction accessory 1, making the overall surface smoother and preventing the accumulation of food residue. Each of the above embodiments can satisfy the requirement that during the traction process, the traction member 2 will not be blocked by the edge of the limiting portion 11 at the contour edge 11a of the partial limiting portion 11 (that is, the traction force is directed toward the side where the contour edge 11a of this part of the limiting portion 11 is located), and can be stably stuck in the limiting groove 14 during the traction process, thereby ensuring the stability and accuracy of the traction force during the correction process.

[0055] In some embodiments, reference Figures 10 to 12 As shown in , the limiting portion 11 can be divided into a first free arm 111a extending along the first direction X1 and a second free arm 112a extending along the second direction X2. One end of the first free arm 111a is connected to the second free arm 112a and the other end is the first free end 111. One end of the second free arm 112a is connected to the first free arm 111a and the other end is the second free end 112. When the first free arm 111a or the second free arm 112a is a straight arm, the long axis direction of the first free arm 111a is the first direction X1, or the long axis direction of the second free arm 112a is the first direction X1. When the first free arm 111a is a curved arm or the second free arm 112a is a curved arm, the line connecting the connection point between the first free arm 111a and the second free arm 112a and the first free end 111 coincides with the first direction X1, or the line connecting the connection point between the second free arm 112a and the first free arm 111a and the second free end 112 coincides with the second direction X2. Of course, the tangent direction of the maximum curvature of the first free arm 111a can also be the first direction X1, or the tangent direction of the maximum curvature of the second free arm 112a can be the second direction X2. It can be understood that the first direction X1 is the overall extension direction of the first free arm 111a, and the second direction X2 is the overall extension direction of the second free arm. The angle between the first direction X1 and the second direction X2 is greater than 90° and less than or equal to 180°. Continue to refer to Figure 9 As shown, when the angle α between the first direction X1 and the second direction X2 is equal to 180°, the first free arm 111a and the second free arm 112a are straight arms as a whole; Figures 11 to 12 As shown, when the angle α between the first direction X1 and the second direction X2 is greater than 90° and less than 180°, the first free arm 111a can be a straight arm or a curved arm, and the second free arm 112a can be a straight arm or a curved arm.

[0056] In some embodiments, in order to further better prevent the traction member 2 from falling off, the first direction X1 and the second direction X2 do not coincide with the traction direction. The advantage of this design is that, whether the traction member 2 is perpendicular to the traction rod 12 or is at an inclined angle to the traction rod 12 (i.e., non-perpendicular) during the traction process, the bottom surfaces of the first free arm 111a and the second free arm 112a can simultaneously prevent the traction member 2 from falling off. Further preferably, referring to Figure 13 As shown, the bending direction of the limiting portion 11 is opposite to the traction direction. This design can further enhance the limiting ability of the limiting portion 11, especially when there is an angle between the traction member 2 and the traction rod 12. The edge of the limiting portion 11 contacted by the traction member 2 extends in the opposite direction to the traction direction, making it difficult for the traction member 2 to slip along the edge of the limiting portion 11.

[0057] In some embodiments, reference Figure 14 and Figure 15 As shown, the limiting portion 11 further includes a first side surface 114 and a second side surface 113 disposed opposite to each other, and at least one of the first side surface 114 and the second side surface 113 is a curved surface. The curved surface design not only improves the comfort of the traction accessory 1 in the mouth, but also further improves the limiting ability of the limiting portion 11 when the curvature direction of the curved surface is inconsistent with the traction direction. Figure 16 As shown, when the first side surface 114 and the second side surface 113 are both curved surfaces, the bending directions of the first side surface 114 and the second side surface 113 are consistent. Such a design of the traction accessory 1 can also serve as an identification and pointing function during use. Specifically, the operator can paste the traction accessory 1 according to the bending direction, so that the direction of the traction force is opposite to the bending direction of the first side surface 114 and the second side surface 113. With such a design, the operator can easily complete the installation of the traction accessory 1. Further preferably, the first side surface 114 and the second side surface 113 are both curved surfaces, and the center of the circle where the projection of the first side surface 114 on the first plane M is located coincides with the center of the circle where the projection of the second side surface 113 on the first plane M is located. Reference Figure 17 As shown, the center of the circle C1 where the first side surface 114 is located and the center of the circle C2 where the second side surface 113 is located are both point O. This design not only makes the restriction of the limiting portion 11 on the traction member 2 more stable, but also improves the comfort of the traction accessory 1 in the mouth.

[0058] Of course, without violating the overall inventive concept of the various embodiments of this application, in some other embodiments, one of the first side surface 114 and the second side surface 113 may be curved while the other is flat. Alternatively, both the first side surface 114 and the second side surface 113 may be flat. This will not be elaborated upon here.

[0059] In some embodiments, reference Figure 18 and Figure 19 As shown, the first free end 111 and the second free end 112 are respectively bent toward the base 13. Such a design can reduce the size of the limiting groove 14, further restrict the movement of the traction member 2 in the limiting groove 14, and thus improve the retention effect of the limiting groove 14 on the traction member 2. Specifically, in order to make the first free end 111 and the second free end 112 be bent toward the base 13, the surface 115 of the limiting portion 11 adjacent to the traction rod 12 includes a concave curved surface and / or an inclined plane, and the concave direction is toward the side of the limiting portion 11 away from the traction rod 12. Figure 19As shown, when the surface of the limiting portion 11 adjacent to the traction rod 12 includes the inclined plane, the angle β between the inclined plane and the long axis PP' of the traction rod 12 is greater than or equal to 30° and less than 90°; Figure 18 As shown, when the surface of the limiting portion 11 adjacent to the side of the traction rod 12 includes the concave curved surface, the angle γ between the tangent line of the highest point on the concave curved surface and the long axis PP' of the traction rod 12 is greater than or equal to 30 degrees and less than 90 degrees. Since in the prior art, the traction member 2 adopts a rubber ring that is elastic itself, the design of the above angle can not only enable the traction member 2 to enter the limiting groove 14 smoothly during assembly, but also during the pulling process, the traction member 2 can be stably maintained in the limiting groove 14 without moving in other directions. It can be understood that, with reference to Figure 18 As shown, the surface 115 of the limiting portion 11 adjacent to the traction rod 12 can be a concave curved surface, or can be a curved surface. Figure 19 As shown, the surface of the limiting portion 11 adjacent to the traction rod 12 may be composed of two planes 115a and 115b inclined in different directions. Of course, it is understood that, provided that the first free end 111 and the second free end 112 are respectively bent toward the base 13, the surface of the limiting portion 11 adjacent to the traction rod 12 may also include both a concave curved surface and an inclined plane. For example, depending on different traction requirements, the surface of the limiting portion 11 adjacent to the traction rod 12 may be partially configured as a concave curved surface and partially configured as an inclined plane.

[0060] In some embodiments, reference Figure 20 As shown, the side wall of the traction rod 12 is provided with a through-hole structure 15 for inserting an archwire and extending through the side wall of the traction rod 12. This design allows for multiple traction methods to be performed simultaneously. Furthermore, preferably, the axial direction of the through-hole structure 15 is angularly offset from the traction direction. This design has the advantage that when the traction accessory 1 simultaneously suspends the traction member 2 and inserts the archwire, the traction direction of the traction member 2 and the position of the archwire do not overlap, thus avoiding interference between the archwire and the traction member 2 when they are aligned.

[0061] One embodiment of the present application also provides a dental device, which includes a shell-shaped body 3 having multiple tooth receiving cavities and a traction attachment 1 as described in any of the above embodiments. The shell-shaped body 3 is an invisible, aesthetically pleasing mechanical device for orthodontics produced through computer three-dimensional design. It is usually worn on the teeth in the mouth and is made of polymer materials, such as TPU, PETG, or a combination of both materials. It can generate a force to cause changes in the deformed jaw, misplaced teeth, and periodontal tissues, which is beneficial to the normal growth and development of the maxillofacial region. The shell-shaped appliance uses the principles of biomechanics to correct deformed teeth. A correction system including a series of shell-shaped appliances applies a gentle and lasting biological force to slowly move the teeth, restore them to their normal position, and align them. The outer surface of the shell-shaped body 3 has a mounting area for the traction attachment 1, and the traction attachment 1 is fixed to the mounting area via a base 13.

[0062] In some embodiments, the mounting area has a mounting platform 31 that protrudes toward the distal tooth direction, and the base 13 is fixed to the mounting platform 31 in a predetermined posture. The base 13 can be directly bonded to the surface of the mounting platform 31. In this case, the mounting platform 31 and the base 13 of the traction member 2 have mutually matching concave and convex shapes, so that the base 13 can be fixed to the surface of the mounting platform 31 in a predetermined posture. Figures 21 to 23 As shown, the mounting platform 31 has a first protruding structure 311, and the base 13 has a first concave structure 131 that cooperates with the first protruding structure along a predetermined direction; or, the mounting platform 31 has a second concave structure (not shown in the figure), and the base 13 has a second protruding structure (not shown in the figure) that cooperates with the second concave structure along a predetermined direction. In some embodiments, reference Figure 23 As shown, the mounting surface profile of the mounting platform 31 substantially matches the bottom surface profile of the base 13, and the mounting surface is generally flat or curved. In the above embodiment, by designing the relationship between the shape of the base 13 and the mounting platform 31, the assembly method of the traction accessory 1 in the installation area is defined, which facilitates the operator and allows easy determination of how to install the traction accessory 1 on the shell body 3 during the assembly process.

[0063] Of course, in some other embodiments, the traction accessory can be passed through the shell body. In other words, the mounting platform has a mounting hole, through which the traction accessory passes, with the base located inside the mounting platform and the stopper located outside the mounting platform. Compared to directly adhering the traction accessory to the surface of the shell body, this approach can improve the mounting stability between the traction accessory and the shell body, preventing the traction accessory from falling off the shell body during use.

[0064] It should be noted that the above embodiments can be freely combined as needed to form different new implementation plans without causing any contradiction. The implementation plans formed by such combination are all within the scope of protection of the present utility model. In order to save the length of the application text, they will not be repeated here.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

[0066] Similarly, the above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A traction attachment for orthodontic treatment, characterized in that: The traction attachment includes a limiting portion, a traction rod, and a base that are sequentially connected, the limiting portion includes a first free end extending in a first direction and a second free end extending in a second direction, the first direction and the second direction do not overlap; A limiting groove for accommodating a traction member is formed at a connection position between the limiting portion and the traction rod, and the traction rod includes a top surface connected to the limiting portion; a projection of a contour edge of part of the limiting portion on the first plane is located within a projection area of ​​the top surface on the first plane, and projections of the first free end and the second free end on the first plane are both located outside the projection area of ​​the top surface on the first plane, wherein the first plane is parallel to a cross-section of the traction rod.

2. The traction attachment according to claim 1, characterized in that The angle between the first direction and the second direction is greater than 90° and less than or equal to 180°.

3. The traction attachment according to claim 2, characterized in that: The first direction and the second direction do not coincide with the pulling direction of the pulling member.

4. The traction attachment according to claim 2, characterized in that: The limiting portion further includes a first side surface and a second side surface that are opposite to each other, and at least one of the first side surface and the second side surface is a curved surface.

5. The towing accessory according to claim 4, characterized in that When both the first side surface and the second side surface are curved surfaces, the curvature directions of the first side surface and the second side surface are consistent.

6. The towing accessory according to claim 4, characterized in that When one of the first side surface and the second side surface is a curved surface, the other side surface is a flat surface.

7. The towing accessory according to claim 5, characterized in that The first side surface and the second side surface are both arc surfaces, and the center of a circle where the projection of the first side surface on the first plane lies coincides with the center of a circle where the projection of the second side surface on the first plane lies.

8. The towing accessory according to claim 1, wherein: The first free end and the second free end are respectively bent toward the base.

9. The towing accessory according to claim 8, characterized in that The surface of the limiting portion adjacent to the traction rod includes a concave curved surface and / or an inclined plane.

10. The towing accessory according to claim 9, characterized in that When the surface of the limiting portion adjacent to the traction rod includes the inclined plane, the angle between the inclined plane and the long axis of the traction rod is greater than or equal to 30° and less than 90°; when the surface of the limiting portion adjacent to the traction rod includes the concave curved surface, the angle between the tangent of the highest point on the concave curved surface and the long axis of the traction rod is greater than or equal to 30° and less than 90°.

11. The towing accessory according to claim 1, wherein: The side wall of the traction rod is provided with a through hole structure for passing an arch wire and penetrating the side wall of the traction rod.

12. The towing accessory according to claim 11, wherein: There is an angle difference between the axial direction of the through hole structure and the pulling direction of the pulling member.

13. A dental instrument, characterized in that: It comprises a shell-shaped body having a plurality of tooth receiving cavities and a traction accessory as claimed in any one of claims 1 to 12, wherein the outer surface of the shell-shaped body has a mounting area for the traction accessory, and the traction accessory is fixed to the mounting area through a base.

14. The dental apparatus according to claim 13, wherein: The installation area has a mounting platform protruding toward the distal tooth direction, and the base is fixed on the mounting platform in a predetermined posture.

15. The dental apparatus according to claim 14, wherein The mounting platform has a first protruding structure, and the base has a first concave structure that cooperates with the first protruding structure along a predetermined direction; or, the mounting platform has a second concave structure, and the base has a second protruding structure that cooperates with the second concave structure along a predetermined direction.

16. The dental apparatus according to claim 14, wherein: The mounting surface profile of the mounting platform substantially matches the bottom surface profile of the base, and the mounting surface is generally flat or curved.

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