Dental bur

Abstract

The dental bur comprises a working part and a handle part which are connected with each other, and the working part comprises a safety structure, a pinniform structure and a cutting structure which are connected in sequence. The safety structure can be in contact with the gingiva or adjacent teeth during adjacent or subgingival operation, so that damage to soft tissues or healthy teeth is avoided. A plurality of right-handed rotation grooves and a left-handed rotation groove are formed in the peripheral side of the working part, the right-handed rotation grooves spirally extend towards the handle part from the safety structure in the axial direction of the working part, pinniform blades and cutting blades are formed between the adjacent right-handed rotation grooves, and redundant cutting on a tooth body can be reduced when the tooth body is prepared by gradually narrowing the front ends of the pinniform blades; and the original form of the tooth shoulder region is reserved to the greatest extent. The left-hand groove spirally extends towards the handle part from the tail end of the feather-shaped blade in the axial direction of the working part, the left-hand groove cuts the cutting blade to form a plurality of cutting teeth and cutting grooves which are distributed discontinuously, a discontinuous tooth-shaped blade-shaped structure is formed, and the cutting-in and grasping effect equal to that of a carborundum structure can be achieved.

Description

Technical Field

[0001] This application relates to the field of dental bur technology, and particularly to a dental bur. Background Technology

[0002] Dental burs are medical devices intended for drilling, milling, grinding, and polishing teeth, and are used on dental handpieces. Prosthodontists primarily use restorative dental burs to prepare teeth for various restorations, including crowns, veneers, inlays, and removable dentures, as well as to adjust occlusion.

[0003] Proximal preparation of teeth is often necessary to create appropriate gaps for restorative materials. This process is called proximal preparation or interproximal gap augmentation, and it requires preparing the tooth to the required thickness without damaging adjacent healthy tooth tissue. However, existing interproximal gap augmentation burs typically come in two forms: one is the diamond-plated bur, where the cutting layer consists of diamond particles electroplated onto a metal bur body. This type of bur initially has strong cutting force, but the plating layer has limited adhesion. During proximal operations, the bur tip is frequently used, making it prone to particle shedding or wear failure, resulting in a short lifespan and frequent replacement. The other type is the carbide-based integral grinding bur. While it has high hardness and wear resistance, the smooth surface of carbide results in insufficient gripping force during cutting, making it prone to slipping on the hard enamel surface. This makes it difficult for dentists to maintain stable control of the cutting angle and may even damage adjacent healthy teeth. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. This application provides a dental bur that has good gripping force and chip removal, enabling smooth cutting of the tooth, while also providing soft tissue protection and a long service life.

[0005] The dental bur according to an embodiment of this application has a working part and a shank part. The working part includes a safety structure, a feather structure, and a cutting structure connected in sequence. The working part has multiple right-handed grooves and one left-handed groove on its periphery. The right-handed groove extends spirally from the safety structure along the axial direction of the working part toward the shank. Feather-shaped cutting edges and cutting edges are formed between adjacent right-handed grooves. The left-handed groove extends spirally from the end of the feather-shaped cutting edge along the axial direction of the working part toward the shank. The left-handed groove is configured to cut the cutting edge to form several discontinuously distributed cutting teeth and cutting grooves.

[0006] The dental burs according to the embodiments of this application have at least the following beneficial effects: The dental bur of this application includes a working part and a shank connected together. The working part includes a safety structure, a feather structure, and a cutting structure connected in sequence. The safety structure can contact the gingiva or adjacent teeth during proximal or subgingival operations, thereby avoiding damage to soft tissue or healthy teeth. Furthermore, the working part of the dental bur has multiple right-handed grooves and one left-handed groove on its periphery. The right-handed groove extends spirally from the safety structure along the axial direction of the working part toward the shank, forming a feather-like edge and a cutting edge between adjacent right-handed grooves. The gradually narrowing tip of the feather-like edge reduces unnecessary cutting of the tooth during preparation, maximizing the preservation of the original morphology of the tooth shoulder area. Finally, the left-handed groove extends spirally from the end of the feather-like edge along the axial direction of the working part toward the shank. The left-handed groove cuts the cutting edge to form several discontinuously distributed cutting teeth and cutting grooves, creating a discontinuous tooth-like blade structure that achieves a cutting and gripping effect equivalent to a diamond abrasive structure.

[0007] According to some embodiments of this application, the outline of the feather-shaped blade is an arc.

[0008] According to some embodiments of this application, the radius of the arc is set to 0.2 mm to 0.8 mm.

[0009] According to some embodiments of this application, the safety structure includes a safety head and a safety tooth, the safety head being disposed at the front end of the working part, and the safety tooth being disposed at the front end of the feather-shaped blade.

[0010] According to some embodiments of this application, the diameter of the safety head is set to 0.01 to 0.5 mm.

[0011] According to some embodiments of this application, the tooth width of the cutting tooth is set to 0 mm to 0.2 mm, the depth of the cutting tooth is set to 0.03 mm to 0.12 mm, and the groove width of the cutting groove is set to 0.1 mm to 0.25 mm.

[0012] According to some embodiments of this application, the helix angle of the right-hand groove is set to 2 degrees to 12 degrees, and the right-hand groove has 6 to 12 grooves.

[0013] According to some embodiments of this application, the working part is configured as a conical structure, and the cone angle of the conical structure is set to 2 degrees to 10 degrees.

[0014] According to some embodiments of this application, the length of the working part is set to 3 mm to 11 mm, and the length of the dental bur is set to 16 mm to 26 mm.

[0015] According to some embodiments of this application, the shank includes a transition portion and a clamping portion. The transition portion includes a first transition section and a second transition section. The cutting structure, the first transition section, the second transition section and the clamping portion are connected in sequence. The first transition section is configured as a cylindrical structure and the second transition section is configured as a tapered structure. Attached Figure Description

[0016] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a plan view of a dental bur according to one embodiment of this application; Figure 2 This is a schematic diagram of the structure of the working part according to one embodiment of this application; Figure 3 Figure 2 Another structural diagram; Figure 4 for Figure 1 A magnified view of a portion of the image; Figure 5 A schematic diagram of the tooth preparation process; Figure 6 A schematic diagram illustrating the process of tooth preparation.

[0017] Figure label: Working part 1; Safety structure 11; Safety head 111; Safety tooth 112; Feather structure 12; Feather blade 121; Cutting structure 13; Cutting tooth 131; Cutting groove 132; Right-hand groove 14; Left-hand groove 15; Handle 2; Transition section 21; First transition segment 211; Second transition segment 212; Clamping part 22; Teeth 3; Shoulder 31; Soft tissue 4. Detailed Implementation

[0018] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0019] In the description of this application, it should be understood that the use of terms such as "center," "middle," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings and is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] The following reference Figures 1 to 6 Describes the dental burs in the embodiments of this application.

[0022] This application relates to a dental bur for tooth preparation. Figure 1 As shown, a dental bur according to one embodiment of this application includes a working part 1 and a shank 2. The working part 1 is the main cutting area, and the shank 2 is connected to the end of the working part 1 for connection with a dental handpiece to transmit rotational driving force to the working part 1. (Continue to see...) Figure 2 and Figure 3 The working part 1 includes a safety structure 11, a feather-shaped structure 12, and a cutting structure 13, which are integrally connected in sequence. The safety structure 11 is located at the front end of the working part 1, that is, at the end of the working part 1 away from the handle 2, and the safety structure 11 has a smooth surface. The feather-shaped structure 12 is located between the safety structure 11 and the cutting structure 13, and the feather-shaped structure 12 extends from its end to its front end (…). Figure 1(As shown) It gradually tapers in an arc shape. The working part 1 has multiple right-handed grooves 14 and one left-handed groove 15 on its periphery. The right-handed grooves 14 extend spirally from the safety structure 11 along the axial direction of the working part 1 toward the shank 2. A cutting edge is formed between adjacent right-handed grooves 14. The cutting edge includes a feather-shaped cutting edge 121 located on the feather-shaped structure and a cutting edge located on the cutting structure, with a continuous transition between the feather-shaped cutting edge 121 and the cutting edge. The left-handed groove 15 extends spirally from the end of the feather-shaped cutting edge 121 along the axial direction of the working part 1 toward the shank 2. The left-handed groove 15 intersects with the right-handed grooves 14. (See reference...) Figure 4 The left-hand groove 15 cuts the cutting edge to form several intermittently distributed cutting teeth 131 and cutting grooves 132, forming a discontinuous tooth-shaped blade structure.

[0023] See also Figure 5 and Figure 6 During vertical tooth preparation, the safety structure 11 first contacts the proximal surface or subgingival region of tooth 3. The rounded end of the safety structure 11 provides protection, ensuring that the cutting process does not damage the soft tissue 4 (such as the gingiva) or healthy tooth structure. Subsequently, the feather structure 12 enters the lateral base of the tooth, and the feather blade 121 cuts and trims it. The gradually narrowing tip of the feather blade 121 allows the lateral base of the tooth to form a feather shoulder structure, reducing unnecessary cutting on the lateral base of the tooth and preserving the original shape of the shoulder area 31 to the greatest extent possible, thus ensuring the strength of the original tooth structure. The right-hand groove 14 and left-hand groove 15 alternate to form several intermittent cutting teeth 131, which perform intermittent contact cutting on the tooth surface during rotation. Only cutting teeth 131 cut on each cutting edge, while the cutting groove 132 area between two adjacent cutting teeth 131 is cut by the cutting teeth 131 of the next cutting edge and / or other cutting edges. This reduces the cutting resistance experienced by each cutting edge and effectively improves the cutting efficiency of the bur. At the same time, due to the lower cutting resistance, the impact of the bur on the tooth 3 during cutting is reduced, improving the patient's experience during tooth preparation and alleviating the patient's fear and discomfort. The chips generated by the cutting teeth 131 can be quickly discharged to the rear end of the working part 1 along the right-hand groove 14 under the action of centrifugal force and helical guiding force. Some chips that enter the cutting groove 132 can enter the subsequent right-hand groove 14 through the cutting groove 132 and be discharged to the rear end of the working part 1, achieving effective chip removal and cooling, and avoiding jamming and overheating caused by continuous cutting. Furthermore, since the cutting teeth 131 are formed by the intersection of the right-hand groove 14 and the left-hand groove 15, the metal on the surface of the needle is divided into countless smaller, independent cutting units, similar to the sharp diamond abrasive grains on the surface of the diamond needle, which can achieve the same cutting and gripping effect as the diamond structure.

[0024] When preparing horizontal tooth structures, the feather-shaped cutting edge 121 with a single spiral direction and continuous cutting surface can also be used to correct and polish the shoulder 31.

[0025] The dental bur of this application firstly reduces the cutting action when it comes into contact with soft tissue 4 or adjacent teeth during high-speed rotation due to the rounded end of the safety structure 11, thereby protecting the gums and healthy teeth. Secondly, compared with conventional cone-shaped cutting edges, the gradually tapering structure of the feather-like structure 12 in this application allows the bur's cutting trajectory to better conform to the tooth shape, achieving precise edge trimming and localized grinding. This ensures tooth preparation while effectively reducing tooth tissue loss, maximizing the preservation of the original tooth structure. Finally, the intermittently arranged cutting teeth 131 and cutting grooves 132 form a cross-shaped chip removal channel, allowing chips to be discharged in a timely manner, reducing wear and overheating, extending the bur's lifespan, and also achieving a diamond-like gripping force for stable cutting of the enamel surface, preventing slippage.

[0026] In some embodiments, see Figure 5 and Figure 6 The dental bur of this application can be used for gap filling in tooth preparation. When performing interproximal gap filling, the tip of the feather structure 12 enters the interdental space with a smaller diameter, thereby reducing unnecessary cutting of the prepared tooth while achieving effective gap filling. This allows the original shape of the shoulder 31 area to be preserved to the greatest extent, avoiding the problem of flattening or overcutting of the shoulder 31 caused by the large cutting area and steep incident angle of traditional gap filling burs.

[0027] In some embodiments, the dental burs of this application are made of carbide, which can maintain a sharp cutting effect for a long time and improve the efficiency of the dentist in creating space during tooth preparation.

[0028] according to Figure 1 and Figure 2 As shown, in one embodiment of this application, the outline of the feather-shaped blade 121 is an arc. The end of the safety structure 11 transitions tangentially to the front end of the arc, forming a smooth transition between the two; the end of the arc transitions tangentially to the front end of the cutting structure 13, ensuring the overall streamlined shape.

[0029] In one embodiment of this application, the radius of the arcuate outline of the feather blade 121 is set to 0.2 mm to 0.8 mm.

[0030] according to Figure 2 and Figure 3As shown, in one embodiment of this application, the safety structure 11 includes a safety head 111 and a safety tooth 112, which can be continuously and integrally arranged. The safety head 111 is disposed at the front end of the working part 1, that is, at the end of the working part 1 away from the handle 2, and the surface of the safety head 111 is provided with a smooth arc end face. The safety tooth 112 is connected to the arc end face of the safety head 111, and the safety tooth 112 is disposed at a preset distance at the front end of each feather blade 121, with a tapered blade surface that transitions at an incline. The front end of the safety tooth 112 is naturally connected to the arc surface of the safety head 111, and the rear end of the safety tooth 112 is smoothly connected to the starting point of the feather blade 121. The blade surface and the adjacent right-handed groove 14 form a cutting edge.

[0031] See Figure 5 and Figure 6 During vertical tooth preparation, the safety head 111 first contacts the gingiva or adjacent tooth, forming a buffer contact area. The rounded end face of the safety head 111 does not have a cutting action, preventing the bur tip from penetrating the soft tissue 4 or healthy tooth, thus fundamentally avoiding damage to the soft tissue 4 and accidental injury to adjacent teeth. Because the tip of the safety head 111 is rounded and has a small diameter, it also serves as an initial positioning tool, helping the dentist accurately determine the cutting starting point during operation, allowing the subsequent cutting edge to smoothly cut the tooth. Furthermore, the soft tissue 4 also provides support for the safety head 111, reducing vibration and impact generated during bur use, keeping the bur stable during cutting, and also reducing wear on the bur tip. The conical cutting surface formed by the safety tooth 112 contacts the tooth or adjacent tooth; the inclined surface of the cutting surface further disperses the contact force, reducing direct cutting of the tooth or soft tissue 4. Furthermore, the tooth body provides support for each cutting surface, allowing the bur to obtain a stable fulcrum during the initial contact phase, reducing bur vibration and impact, and thus improving the smoothness of bur operation. At the same time, the cutting edge of the safety tooth 112 remains moderately sharp, providing a good transition cut for the subsequent introduction of the feathered cutting edge 121 and the penetration of the cutting edge.

[0032] Therefore, the dental bur of this application, through the setting of safety head 111 and safety tooth 112, can simultaneously take into account the dual functions of cutting and buffering. While reducing accidental cutting damage to soft tissue 4 or adjacent tooth surfaces, it reduces cutting vibration, prevents shaking and jumping under high-speed rotation of the bur, and improves surgical stability. In addition, the dental bur of this application also has a slight grinding function, which prepares for subsequent cutting to form an accurate cutting path, realizes a natural transition from the non-cutting area to the cutting area, and improves the overall smoothness of operation.

[0033] according to Figure 3 As shown, in one embodiment of this application, the radius of the safety head 111 is set to R, where R is set to 0.005 to 0.25 mm.

[0034] In some embodiments, the length of the safety tooth 112 is set to 0.1 mm to 0.5 mm.

[0035] according to Figure 4 As shown, in one embodiment of this application, the tooth width of the cutting tooth 131 is set to S, where S is set to 0 mm to 0.2 mm, and the depth of the cutting tooth 131 is set to H, where H is set to 0.03 mm to 0.12 mm. By controlling the tooth width S and depth H of the cutting tooth 131, the structural strength of the cutting tooth 131 is ensured, and damage to the cutting tooth 131 due to increased feed speed during the cutting process is avoided. The groove width of the cutting groove 132 is set to W, where W is set to 0.1 mm to 0.25 mm. By controlling the groove width W of the chip groove and the depth H of the cutting tooth 131, chip removal space is ensured, allowing chips to be smoothly discharged.

[0036] Therefore, the dental bur of this application optimizes the key parameters of the cutting teeth 131 and the cutting groove 132 to better disperse the cutting resistance, so that the force between each cutting tooth 131 is balanced, avoiding the phenomenon of continuous cutting edge slipping or shaking on the hard enamel surface. During the cutting process, it can effectively grasp the hard and smooth enamel, effectively reducing the force required for the doctor to control the bur during the cutting process.

[0037] according to Figures 1 to 4 As shown, in one embodiment of this application, adjacent right-hand grooves 14 form a cutting edge. The helix angle of the right-hand grooves 14 is set to β, which is between 2 and 12 degrees. This means the helix angle of the cutting edge is also between 2 and 12 degrees. The precise setting of the helix angle allows chips to be quickly discharged along the groove line of the right-hand grooves 14 under centrifugal force, preventing chip accumulation that could lead to dulling or jamming of the cutting edge. There are 6 to 12 right-hand grooves 14, meaning there are 6 to 12 cutting edges. This ensures a moderate distribution density of the cutting edges, evenly distributes the cutting force, and provides high balance during rotation, avoiding vibration. The dental bur of this application achieves the technical effects of smooth cutting and chip removal during use by setting an appropriate number of right-hand grooves 14 and a suitable range of helix angles for the right-hand grooves 14.

[0038] according to Figure 1 and Figure 2 As shown, in one embodiment of this application, the working part 1 is configured as a tapered structure, gradually thickening from the safety structure 11 at the front end towards the shank 2 along the axial direction of the needle. The taper angle of the tapered structure is set to α, which is between 2 and 10 degrees. By controlling the taper of the working part 1, not only can the structural strength of the working part 1 be improved to avoid needle breakage, but it can also provide the doctor with a field of vision and better control the entire operation process.

[0039] according to Figure 1As shown, in one embodiment of this application, the length of the working part 1 is set to L1, which is 3mm to 11mm. The total length of the dental bur is set to L2, which is 16mm to 26mm, which can fully meet the space requirements for tooth preparation at different positions in the oral cavity.

[0040] In some preferred embodiments, the total length L2 of the dental bur is set to 16.5 mm, which enables better tooth preparation in narrow spaces at the distal position of the second and third molars.

[0041] according to Figure 1 As shown, in one embodiment of this application, the handle 2 includes a transition portion 21 and a clamping portion 22. The transition portion 21 is located between the working portion 1 and the clamping portion 22 and is used to connect the working portion 1 and the clamping portion 22. The clamping portion 22 is located at the end of the bur and is in close contact with the dental handpiece cassette to transmit rotational torque.

[0042] The transition section 21 includes a first transition segment 211 and a second transition segment 212. The cutting structure 13, the first transition segment 211, the second transition segment 212 and the clamping part 22 are connected in sequence. The first transition segment 211 is set as a cylindrical structure and the diameter of the first transition segment 211 is smaller than the diameter of the clamping part 22 to form a clearance area. Meanwhile, the second transition segment 212 is set as a conical structure, which can provide better operating line of sight for doctors.

[0043] Comparative Test: Comparative Test 1: The dental bur of this application was compared with a conventional diamond TC-26 bur in a clinical setting to improve the efficiency of posterior proximal preparation. The mesial preparation time for posterior teeth was recorded. Under the same experimental conditions, the specific test results are as follows:

[0044] It is evident that the dental burs of this application are sharper and more durable than conventional diamond TC-26 burs. When the gap is widened to the third tooth, the total preparation time of this application is significantly reduced to only 40% of that of the control group.

[0045] Comparative Test 2: The dental bur of this application was compared with a conventional diamond TC-26 bur in a cutting test on a 3*3 cm Macor ceramic block, and the cutting time was recorded. Under the same experimental conditions (same applied force of 20g, same handpiece speed of 150,000 rpm), the specific test results are as follows:

[0046] It is evident that the dental bur of this application is sharper than the conventional diamond TC-26 bur and takes less time to cut through. The control group's bur takes 4.8 times longer to complete the 15th cut than the bur of this application.

[0047] Therefore, the dental bur of this application firstly utilizes a rounded end face structure in its safety head 111. This prevents cutting action when the bur contacts the gingiva or adjacent healthy tooth structure during high-speed rotation, fundamentally preventing soft tissue damage. The rounded end face and small diameter of the safety head 111 also provide initial positioning, while the soft tissue provides counter-support to the bur, reducing vibration. The safety tooth 112 employs a cutting face and cutting edge structure, balancing cutting and support before cutting. Under the counter-support of the tooth or soft tissue 4, the cutting face of the safety tooth 112 stabilizes the bur's posture, reducing tooth removal. The cutting edge of the safety tooth 112 provides a foundation for the subsequent transition to the feathered edge 121 and the cutting edge. Therefore, the safety structure 11 achieves four functions: protection, positioning, vibration reduction, and transition. Secondly, the feathered structure 12 effectively reduces tooth tissue loss and preserves the original tooth structure to the greatest extent possible. During clinical procedures, the safety structure 11 is responsible for front-end protection and positioning, while the feather structure 12 provides both protection and a smooth transition. The safety structure 11 and feather structure 12 are continuously connected and inseparable, forming a buffer transition from the non-cutting area to the cutting area. This ensures a smooth and controllable cutting process, significantly reducing the risk of accidental injury and vibration. It allows the bur to effectively enter the operating space during interproximal clearance preparation, avoiding damage to soft tissue 4 and healthy tooth structure, while preserving the original tooth structure to the greatest extent possible, significantly improving safety and maneuverability. Simultaneously, it solves the technical problem of large bur tip usage and rapid wear during interproximal preparation, thus significantly increasing bur lifespan, reducing bur replacement frequency during clinical procedures, and improving the efficiency of interproximal preparation by the dentist. Finally, the cutting teeth 131 and cutting grooves 132 create an independent cutting unit for each cutting tooth 131, intermittently contacting the tooth structure to achieve a near-diamond-like cutting gripping force. This maintains the advantages of the carbide cutting edge's sharpness and wear resistance while significantly improving adhesion to smooth enamel and cutting control, preventing slippage.

[0048] In the description of this specification, the use of terms such as "an embodiment," "some examples," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples" indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. A dental bur comprising a working portion and a shank portion, wherein the working portion comprises a safety structure, a feather structure and a cutting structure connected in sequence, a plurality of right-hand grooves and a left-hand groove are arranged on the peripheral side of the working portion, the right-hand grooves extend helically along the axial direction of the working portion from the safety structure towards the shank portion, the adjacent right-hand grooves form a feather blade and a cutting blade, the left-hand groove extends helically along the axial direction of the working portion from the end of the feather blade towards the shank portion, and the left-hand groove is configured to cut the cutting blade to form a plurality of intermittently distributed cutting teeth and cutting grooves. The dental bur is made of cemented carbide. The profile line of the feather blade is a circular arc.

2. The dental explorer according to claim 1, wherein: The radius of the circular arc is set to 0.2mm to 0.8mm.

3. The dental bur according to claim 2, wherein: The safety structure comprises a safety head and safety teeth, the safety head is arranged at the front end of the working portion, and the safety teeth are arranged at the front end of the feather blade.

4. The dental bur according to claim 1 or 2, wherein: The diameter of the safety head is set to 0.01 to 0.5mm.

5. The dental bur according to claim 4, wherein: The tooth width of the cutting tooth is set to 0mm to 0.2mm, the depth of the cutting tooth is set to 0.03mm to 0.12mm, and the groove width of the cutting groove is set to 0.1mm to 0.25mm.

6. The dental bur according to claim 1 or 2, wherein: The helix angle of the right-hand groove is set to 2 degrees to 12 degrees, and the right-hand groove is provided with 6 to 12.

7. The dental explorer according to claim 1, wherein: The working portion is provided in a conical structure, and the taper angle of the conical structure is set to 2 degrees to 10 degrees.

8. The dental explorer according to claim 1, wherein: The length of the working portion is set to 3mm to 11mm, and the length of the dental bur is set to 16mm to 26mm.

9. The dental explorer according to claim 1, wherein: The shank portion comprises a transition portion and a clamping portion, the transition portion comprises a first transition section and a second transition section, the cutting structure, the first transition section, the second transition section and the clamping portion are connected in sequence, the first transition section is provided in a cylindrical structure, and the second transition section is provided in a conical structure.

10. The dental bur according to claim 1 or 2, wherein: ​

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