Dental contra-angle handpiece, designed to treat hard materials in a patient's oral cavity

Abstract

DENTAL CONTRALANGLE, INTENDED FOR TREATMENT OF HARD MATERIALS IN THE ORAL CAVIT OF A PATIENT Dental contra-angle (1), intended for treating hard materials in the oral cavity of a patient, comprising an outer sleeve (2), provided with a gripping portion (2A), which extends along a longitudinal axis (3) and a head portion (2B) which extends along a rotational axis (4), a clamping force (5) for holding a treatment tool intended for treating hard materials, the clamping force (5) being housed in the head portion (2B) in a rotatable manner about the rotational axis (4) by a first and second bearing (6, 7) and a coupling device (8) on the gripping portion (2A), intended for connecting the dental contra-angle (1) with a power supply and / or control device,the transmission ratio of the rotational speed of the dental contra-angle (1) amounting to 1:4 ± 3% and the clamping force (5) demonstrating an extraction force greater than 35N according to ISO 14457:2017.

Description

Title of the invention: DENTAL CONTRARY ANGLE, INTENDED FOR TREATMENT OF HARD MATERIALS IN A PATIENT'S ORAL CAVITY

[0001] The present invention relates to a dental contra-angle, which is designed to be suitable for treating hard material in the oral cavity of a patient.

[0002] Artificial dental crowns and dental prostheses, such as dental bridges, are made from various materials. In recent years, zirconia has become the preferred and increasingly common material for this purpose. This is due, among other things, to the fact that zirconia is allergen-free, its shade is very close to the natural shade of teeth, and its increased hardness offers significant advantages, particularly for dental prostheses that replace multiple teeth. However, it is precisely this increased hardness that presents a real challenge for dentists, especially when it comes to treating, for example, the removal of a zirconia dental crown or prosthesis from a patient's oral cavity. Currently, this operation is performed using conventional contra-angles, which are, however, designed for treating softer materials, such as natural dental tissues or cavities.The use of contra-angles of this type for the treatment of hard materials, particularly zirconia, but also other ceramics or particularly hard metal alloys in a patient's oral cavity, results in either very long treatment times or rapid wear, or even breakage of parts of the contra-angles that are particularly stressed during the treatment of hard materials.

[0003] Therefore, the object of the present invention is to design a dental contra-angle handpiece that is particularly suitable for treating hard materials in a patient's oral cavity. The dental contra-angle handpiece must be constructed in such a way as to better withstand the high forces generated during the treatment of hard materials in a patient's oral cavity, both by the hard material itself and by the user of the dental contra-angle handpiece.

[0004] This objective is achieved according to the present invention by a dental contra-angle handpiece intended for treating hard materials in the oral cavity of a patient, comprising an outer sleeve delimiting the dental contra-angle handpiece from the environment, provided with a gripping portion extending along a longitudinal axis and a head portion extending along a rotational axis, the longitudinal axis and the rotational axis being positioned relative to each other at an angle other than 0°, and a clamping forceps for holding a treatment tool intended for treating hard materials. The clamping force is housed in the head portion and rotates around the axis of rotation by means of first and second bearings. A coupling device on the gripping portion connects the dental contra-angle handpiece to a power supply and / or control device. According to the invention, the transmission ratio of the dental contra-angle handpiece's rotational speed is 1:4 ± 3%, and the clamping force demonstrates an extraction force of over 35 N according to ISO 14457:2017. Particularly advantageous embodiments are described.

[0005] In one embodiment of the contra-angle, the first and second bearing are each housed on a first and second bearing seats, the first and second bearing seats being provided on the same bearing body of the head part.

[0006] In one embodiment of the contra-angle, an angular gear is placed in the gripping part.

[0007]

[0008] In one embodiment of the contra-angle, a first toothed wheel of the angular gear protrudes into an orifice in a bearing pad, in which a second toothed wheel of the angular gear is placed such that the first toothed wheel and the second toothed wheel mesh with each other.

[0009] In one embodiment of the contra-angle, the clamping clamp is designed as a clamping clamp by complementary force, provided with several spring arms designed elastically with respect to the axis of rotation.

[0010] In one embodiment of the contra-angle, the clamping forceps includes a tool housing orifice and a tool guide portion, the treatment tool being capable of being inserted into and removed from the dental contra-angle through the tool housing orifice, and in the tool guide portion a rod of the treatment tool being supported in a radial direction relative to the axis of rotation, the tool guide portion having an inner diameter of 1.6 mm and extending from the tool housing orifice with a length of at least 4.5 mm in the direction of the spring arms of the clamping forceps.

[0011] In one embodiment of the contra-angle, the tool guide part extends to a part of the clamping collet which connects to the tool guide part and whose inner diameter is different from 1.6 mm.

[0012] In one embodiment of the contra-angle, the clamping clamp, including a keyed sleeve intended to detach the treatment tool from the clamping clamp, has a length of at least 12 mm.

[0013] In one embodiment of the contra-angle, the first and second bearing seats are designed by surfaces of the bearing body designed substantially parallel to the axis of rotation.

[0014] In one embodiment of the contra-angle, the bearing body is constituted by the inner face of the head part.

[0015] In one embodiment of the contra-angle, each of the first and second bearing supports has an external bearing track having a peripheral surface which is housed on the first and second bearing seats.

[0016] In one embodiment of the contra-angle, at least the first or second bearing has at least nine rolling elements.

[0017] In one embodiment of the contra-angle, at least the first or second bearing is designed as a shoulder bearing.

[0018] In one embodiment of the contra-angle, a push button is provided on the head part, intended to detach the treatment tool from the clamping forceps, the push button having an outside diameter of at least 9.0 mm.

[0019] In one embodiment of the contra-angle, for differentiating the dental contra-angle, the push button has a marking.

[0020] In one embodiment of the contra-angle, a maximum of three orifices are placed in a circle around the tool housing orifice, for the distribution of a cooling agent.

[0021] In one embodiment of the contra-angle, a light-emitting device is placed on or adjacent to the head portion, for the distribution of light onto the treatment tool and / or the treatment area.

[0022] The dental contra-angle according to the invention, intended for treating hard materials in a patient's oral cavity, comprises an outer sleeve, which delimits the dental contra-angle from its surroundings and which includes a gripping portion extending along a longitudinal axis and a head portion extending along a rotational axis. The longitudinal axis and the rotational axis are positioned relative to each other at an angle other than 0°, such that a treatment tool intended for treating hard materials extends beyond the dental contra-angle, forming an elbow relative to the gripping portion or the longitudinal axis.

[0023] The dental contra-angle also includes a clamping clamp, for holding the treatment tool intended for treating hard materials, the clamping clamp being housed in the head part in a rotatable manner around the axis of rotation by a first and a second bearing bearing, as well as a coupling device on the gripping part, intended to connect the dental contra-angle with a power supply and / or control device and / or with a motor drive device.

[0024] The transmission ratio of the rotational speed of the dental contra-angle handpiece according to the invention is 1:4 ± 3%. By way of example, the maximum input rotational speed (which clearly depends on the drive motor provided on the dental contra-angle handpiece) is 40,000 rpm, and the maximum output speed is therefore 160,000 rpm. The rotational speed transmission ratio of 1:4 ± 3% thus provides a low maximum rotational speed compared to other contra-angle handpieces intended for restorative and prosthetic use, thereby reducing wear on the rotating structural elements of the dental contra-angle handpiece.The reduced wear compensates for the high stress exerted on the rotating structural elements of the dental contra-angle during the treatment of hard materials in the oral cavity; thus, the rotational speed transmission ratio of 1:4 ± 3% increases the lifespan of the dental contra-angle, despite the higher stresses experienced during the treatment of hard materials.

[0025] The clamping force of the dental contra-angle handpiece according to the invention demonstrates an extraction force of more than 35 N, preferably more than 36 N, according to ISO 14457:2017. The extraction force is therefore increased compared to other contra-angles intended for restorative and prosthetic work. The increased extraction force means that the clamping force holds the treatment tool (rotary instrument) with greater force; that is, the clamping force of the clamping force is increased. The extraction force or clamping force is estimated to be preferably about 20% greater compared to other contra-angles intended for restorative and prosthetic work.The increased extraction force or clamping force is due, for example, to a greater wall thickness in at least some parts of the clamping forceps and / or to an enlargement of the clamping forceps, for example, its elongation compared to other contra-angles intended for restorative and prosthetic work, and / or to specific geometric characteristics of at least some parts of the clamping forceps. Advantageously, the increased extraction force or clamping force results in the clamping forceps being able to reliably hold the treatment tool, despite the high mechanical stress experienced when treating hard materials in a patient's oral cavity.

[0026] The first and second bearings of the dental contra-angle handpiece according to the invention are each preferably housed on a first and a second bearing seat, the first and second bearing seats being provided on the same bearing body of the head portion. This feature has the effect of increasing, in particular, the mechanical stability of the dental contra-angle handpiece, which, compared to other contra-angles intended for restorative and prosthetic use, allows it to better withstand the stresses experienced during the treatment of hard materials in a patient's oral cavity. The bearing body is preferably designed as a single piece for example, in the form of a bearing housing designed within the head portion or by the inner face of the head portion of the outer sleeve. The bearing body may, however, also consist of several parts that are connected to each other in such a way as to form a single structural element, from an operational point of view, and / or to act operationally as a structural element designed as a single unit.

[0027] Thus, each individual characteristic mentioned above advantageously enhances the suitability of the dental contra-angle handpiece according to the invention for treating hard materials, particularly zirconia, in a patient's oral cavity. The combination of several, or even all, of these characteristics, which advantageously further enhance the suitability of the dental contra-angle handpiece according to the invention for treating hard materials, also through synergistic effects, is particularly advantageous. For example, the rotational speed transmission ratio of 1:4 ± 3% not only reduces the stress on the drive train, but also reduces the stress on the clamping forceps, in addition to the previously described adapted geometry or modified dimensions of the clamping forceps.In accordance with the above, providing the first and second bearing seats on the same bearing body for the clamping collet also has advantages, because the pressure force exerted by the user on the hard material to be processed is transferred from the clamping collet to the bearing housings and the bearing body and can be absorbed by the latter, which has the effect of unloading the clamping collet.

[0028] The invention is explained below with the aid of preferred embodiments and with reference to the accompanying drawings. The figures represent

[0029] [Fig.1] The [Fig.1]: an external lateral view of a dental contra-angle intended for treating hard materials in the oral cavity of a patient;

[0030] [Fig.2] The [Fig.2]: an elevation view on the dental contra-angle of the [Fig.1];

[0031] [Fig.3] The [Fig.3]: a partial section of a dental contra-angle handpiece intended for treating hard materials in a patient's oral cavity.

[0032] The dental contra-angle 1 intended for treating hard materials, in particular zirconia in the oral cavity of a patient shown in Figures 1 to 3, comprises an outer sleeve 2 delimiting the dental contra-angle 1 from the environment, provided with a gripping part 2A, which extends along a longitudinal axis 3 and a head part 2B, which extends along a rotation axis 4. The longitudinal axis 3 and the rotation axis 4 are placed relative to each other at an angle other than 0°, so that a treatment tool (not shown) intended for treating hard materials protrudes from the dental contra-angle 1 by forming a bend relative to the gripping part 2A or relative to the longitudinal axis 3.

[0033] A clamping clamp 5 is provided in the head portion 2B, ensuring the retention of the treatment tool intended for treating hard materials. The clamping clamp 5 is housed in the head portion 2B and rotates around the axis of rotation 4 by a first and second bearing 6, 7, in particular ball bearings. The clamping clamp 5 exhibits an extraction or clamping force for the treatment tool of more than 35 N according to ISO 14457:2017, which ensures reliable fixation of the treatment tool even when treating hard materials in a patient's oral cavity.

[0034] The clamping clamp 5 is preferably designed in the form of a clamping clamp by complementary force or by friction, with several spring arms 17 designed elastically with respect to the axis of rotation 4. Advantageously, the clamping clamp 5 by complementary force is able to provide sufficient clamping force to hold the tool for processing a hard material in the oral cavity of a patient.

[0035] The clamping forceps 5 further includes a tool housing 18 and a tool guide portion 5A. Through the tool housing 18, the treatment tool can be inserted into and removed from the clamping forceps 5 and the dental contra-angle 1. In the tool guide portion 5A, a shaft of the treatment tool bears radially to the axis of rotation 4, particularly if, during the treatment of a hard material in a patient's oral cavity, radial forces (relative to the axis of rotation 4) act on the treatment tool. The tool guide portion 5A preferably has an inner diameter of 1.6 mm so that, when inserted into the clamping forceps 5, the shaft of the treatment tool comes into contact with the inner wall or is at least separated from it by only a minimal air gap.The tool guide portion 5A extends in particular from the tool housing orifice 18 with a length of at least 4.5 mm, preferably at least 5.0 mm, towards the spring arm 17 of the clamping collet 5. The length of the tool guide portion 5A of at least 4.5 mm, increased compared to other contra-angles intended for restoration and prosthetics, and the inner diameter of 1.6 mm, thus reliably support the processing tool on a longer portion of the tool shank when processing hard material, advantageously ensuring increased mechanical stability, as required for the processing of hard material.

[0036] The tool guide portion 5A extends for a length of at least 4.5 mm from the tool housing orifice 18, in particular to a portion 5B of the collet 5 which connects to the tool guide portion 5A, the inner diameter of which is different from 1.6 mm. The connected portion 5B of the collet 5 includes, for example, a clamping portion of the collet 5 and / or the spring arms 17 of the clamping collet 5 and / or a portion of the clamping collet 5 with an inner diameter greater than 1.6 mm and / or a portion of the clamping collet 5 with an inner diameter less than 1.6 mm. The tool guide portion 5A is positioned, in particular, between the tool housing orifice 18 and the spring arms 17 of the clamping collet 5. The tool guide portion 5A is provided, in particular, in the area of ​​the second bearing 7, which is positioned closer to the tool housing orifice 18, so that, advantageously, forces acting on the treatment tool are directly transmitted via the second bearing to the head portion 2B of the dental contra-angle 1.

[0037] Preferably, the clamping collet 5, including a keyed sleeve 19 for disengaging the processing tool from the clamping collet 5, has a length or total length of at least 12 mm. Thus, the total length of at least 12 mm of the clamping collet 5, increased compared to other contra-angles intended for restoration and prosthetics, reliably supports the processing tool over a greater portion of the tool shank when processing hard materials and advantageously ensures increased mechanical stability, as required for processing hard materials.

[0038] The first and second bearing or ball bearing 6, 7, which rotatably house the clamping clamp 5 in the head portion 2B, are each housed on a first and second bearing seat 10, 11, the first and second bearing seats 10, 11 being provided on the same bearing body 9 of the head portion 2B. As the two bearing seats 10, 11 and therefore in particular also the two bearings 6, 7 are provided on the same bearing body 9, the dental contra-angle 1 demonstrates increased mechanical robustness (compared with other contra-angles intended for restoration and prosthetics, on which the bearing seats are provided on two different bearing bodies), such as is required for the treatment of hard material in a patient's oral cavity.

[0039] The first and second bearing seats 10, 11 are formed by surfaces 20 of the bearing body 9 designed substantially parallel to the axis of rotation 4. Preferably, the bearing body 9 is formed by the head portion 2B and / or the surfaces 20 are formed by the inner face of the head portion 2B of the outer sleeve 2. Thus, no additional bearing body is advantageously required to form the bearing seats 10, 11 and / or to house the bearing housings 6, 7. It goes without saying that, alternatively, the bearing body 9 may be designed with the bearing seats 10, 11 as a separate structural element, placed in the head portion 2B, for example in the form of a bearing pad.

[0040] The bearing housings 6, 7 preferably each comprise an outer, substantially cylindrical raceway provided with an enveloping surface or outer peripheral surface 21, 22. Preferably, each time a peripheral surface 21, 22 of an outer raceway of the first and second bearing 6, 7 is housed in a rotationally fixed manner on the first and second bearing seat 10, 11.

[0041] Preferably, at least the first and / or second bearing 6, 7 comprises ceramic components. In particular, the rolling elements of the first and / or second bearing 6, 7 are made of a ceramic material.

[0042] Preferably, at least the first and / or second bearing 6, 7 comprises at least nine rolling elements. This represents a higher number of rolling elements compared to other contra-angles intended for restorative and prosthetic work. Thus, the forces acting on the treatment tool and the dental contra-angle 1 during the treatment of hard material in a patient's oral cavity are advantageously distributed over a greater number of rolling elements, thereby conferring increased robustness to the bearings 6, 7 and the dental contra-angle 1, which are better suited for treating hard material in a patient's oral cavity. The rolling elements preferably have a diameter of approximately 1 mm.

[0043] Preferably, at least the first and / or second bearing 6, 7 is designed as a shoulder bearing. Advantageously, the bearings 6, 7 designed as shoulder bearings are particularly suitable for absorbing forces which, during the treatment of a hard material in a patient's oral cavity, act on the treatment tool and on the dental contra-angle 1.

[0044] On the end of the gripping portion 2A that is away from the head portion 2B, a coupling device 8 is provided for connecting the dental contra-angle handpiece 1 to a power supply and / or control device and / or to a drive device, in particular an electric motor. The drive device may be either integrated into the outer sleeve 2 of the dental contra-angle handpiece 1, or, as a separate component, may be removably connected to the dental contra-angle handpiece 1 via the coupling device 8.

[0045] In the gripping part 2A, specifically in the area of ​​a curve in the gripping part 2A, a bevel gear 12 is provided. For this purpose, a driven shaft 26 carries a first gear or pinion 13 and a driving shaft 27 carries a second gear 16. The first and second gears 13, 16 mesh with each other and constitute the bevel gear 12, which serves as the first transmission gear. In or on the head portion 2B, an additional bevel gear 28 is provided. It comprises a third gear 29 on the driven shaft 26 and teeth 30, rotationally fixed to the clamping jaw 5, which mesh with each other and constitute the bevel gear. 28 is constituted as the second transmission gear. Thus, the angular gear 28 is designed to transmit the drive displacement and the rotational torque to the clamping forceps 5. Due to the number of their teeth, the two angular gears 12 and 28 are, for example, designed and interact in such a way that the transmission ratio of the rotational speed of the dental contra-angle (1) is 1:4 ± 3%. This rotational speed transmission ratio of 1:4 ± 3% has proven to be particularly suitable for the treatment of hard materials in a patient's oral cavity, both in terms of the rotational torque with which the hard material is treated, the duration of the treatment of the hard material, and the wear of the particularly stressed components of the dental contra-angle 1.

[0046] The two shafts 26, 27 are rotated by means of roller bearings within bearing housings 15 and 31. The bearing housings 15, 31 advantageously also serve to protect the gears 12, 28 and the roller bearings against the ingress of particles from the hard material being processed. To ensure that the first output gear 13 and the second input gear 16 mesh with each other, despite being enclosed by the bearing housings 15, 31, an opening 14 is provided in the bearing housing 15, which receives the second gear 16. The first gear 13 protrudes through this opening. To ensure its sealing, the opening 14 is surrounded by a sealing element, for example, an O-ring.

[0047] Preferably, a push button 23 is provided on the head portion 2B, intended to disengage the processing tool from the clamping collet 5. The push button 23 is located, in particular, on the end of the head portion 2B opposite the tool housing orifice 18. The push button 23 is designed to be movable relative to the outer sleeve 2, in particular to the head portion 2B. The push button 23 is movable in particular in a known manner in the direction of the tool housing orifice 18, as a result of which the keyway 19 also moves in the direction of the tool housing orifice 18 and the wedge-shaped extension of the keyway 19 engages in the spring arms 17 of the clamping sleeve 5 and moves them away from each other in a radial direction, so that the processing tool can be inserted into or removed from the clamping sleeve 5.

[0048] The push button 23 preferably has an outside diameter of at least 9.0 mm. This advantageously facilitates the freedom of manipulation of the push button 23, particularly with regard to the previously mentioned extraction or clamping force of the clamping sleeve 5.

[0049] To differentiate the dental contra-angle 1 from other dental contra-angles, particularly other dental contra-angles intended for restorative and prosthetic use, the push button 23 has a marking. The marking on the button The push button 23 preferably includes a color marking and / or alphanumeric marking or a symbol. Most preferably, the push button 23 is provided with a colored marking in the form of a circular shape or a circular surface, in black, for example, see [Fig. 2]. To differentiate them, the dental contra-angles have a colored plastic ring on their tip, near the coupling device 8. The marking provided on the push button 23 further facilitates and makes more reliable the identification and differentiation of the dental contra-angle 1 intended for treating hard materials in a patient's oral cavity, which further advantageously reduces the likelihood of misuse of the dental contra-angle 1 intended for treating hard materials.

[0050] The dental contra-angle handpiece 1 preferably comprises a maximum of three orifices 24 arranged in a circle around the tool housing orifice 18, for distributing a cooling agent, in particular an air / water vaporizer. This feature also advantageously increases the robustness of the dental contra-angle handpiece 1 compared with other dental contra-angle handpieces intended for restorative and prosthetic use that are provided with more than three cooling agent distribution orifices 24.

[0051] A light-emitting device 25 for emitting light onto the treatment tool and / or the area to be treated is preferably provided on the dental contra-angle 1, in particular on the head portion 2B, or adjacent thereto. This advantageously improves the visibility of a hard material to be treated for the user. The light-emitting device 25 comprises, for example, a light conductor made of glass or plastic and / or a light source, in particular a light-emitting diode (LED).

[0052] The embodiments described or represented serve in particular to illustrate the invention. Thus, the features disclosed in an embodiment are not restricted to said embodiment, but may be associated individually or jointly with one or more features of other embodiments.

Claims

Demands

1. A dental contra-angle (1) for treating hard materials in a patient's oral cavity, comprising an outer sleeve (2) delimiting the dental contra-angle (1) from its surroundings, having a gripping portion (2A) extending along a longitudinal axis (3) and a head portion (2B) extending along a rotational axis (4), the longitudinal axis (3) and the rotational axis (4) being positioned relative to each other at an angle other than 0°, a clamping force (5) for holding a treatment tool for treating hard materials, the clamping force (5) being housed in the head portion (2B) in a rotatable manner about the rotational axis (4) by first and second bearings (6, 7), and a coupling device (8) on the gripping portion (2A) for connecting the dental contra-angle (1) with a power supply and / or control device,characterized in that the transmission ratio of the rotational speed of the dental contra-angle (1) is 1:4 ± 3% and in that the clamping force (5) demonstrates an extraction force of more than 35N according to ISO 14457:2017.

2. Dental contra-angle (1) according to claim 1, characterized in that the first and second bearing bearing (6, 7) are each housed on a first and second bearing seats (10, 11), the first and second bearing seats (10, 11) being provided on the same bearing body (9) of the head part (2B).

3. Dental contra-angle (1) according to any one of the preceding claims, characterized by an angular gear (12) placed in the gripping part (2A).

4. Dental contra-angle (1) according to claim 3, characterized in that a first toothed wheel (13) of the angular gear (12) protrudes into an orifice (14) in a bearing pad (15), in which a second toothed wheel (16) of the angular gear (12) is placed such that the first toothed wheel (13) and the second toothed wheel (16) mesh with each other.

5. Dental contra-angle (1) according to any one of the preceding claims, characterized in that the clamping clamp (5) is designed as a clamping clamp by complementary force, provided with several spring arms (17) designed elastically with respect to the axis of rotation (4).

6. Dental contra-angle (1) according to claim 5, characterized in that the clamping clamp (5) has a tool housing orifice (18) and a tool guide portion (5A), the treatment tool being capable of being inserted into the dental contra-angle (1) and removed from it through the tool housing orifice (18), and in the tool guide portion (5A) a shank of the treatment tool being supported in a radial direction with respect to the axis of rotation (4), the tool guide portion (5A) having an inner diameter of 1.6 mm and extending from the tool housing orifice (18) with a length of at least 4.5 mm in the direction of the spring arms (17) of the clamping clamp (5).

7. Dental contra-angle (1) according to claim 6, characterized in that the guiding part (5A) of the tool extends to a part (5B) of the clamping clamp (5) which connects to the guiding part (5A) of the tool (5) and whose inner diameter is different from 1.6 mm.

8. Dental contra-angle (1) according to any one of the preceding claims, characterized in that the clamping clamp (5) including a keyed sleeve (19) intended to detach the treatment tool from the clamping clamp (5) has a length of at least 12 mm.

9. Dental contra-angle (1) according to any one of claims 2 to 8, characterized in that the first and second bearing seats (10, 11) are designed by surfaces (20) of the bearing body (9) designed substantially parallel to the axis of rotation (4).

10. Dental contra-angle (1) according to any one of claims 2 to 9, characterized in that the bearing body (9) is constituted by the inner face of the head part (2B).

11. Dental contra-angle (1) according to any one of claims 2 to 10, characterized in that each of the first and second bearing supports (6, 7) have an external bearing raceway comprising a peripheral surface (21, 22) which is housed on the first and second bearing seats (10, 11).

12. Dental contra-angle (1) according to any one of claims 2 to 11, characterized in that at least the first or second bearing support (6, 7) comprises at least nine rolling elements.

13. Dental contra-angle (1) according to any one of claims 2 to 12, characterized in that at least the first or second bearing support (6, 7) is designed as a shoulder bearing.

14. Dental contra-angle (1) according to any one of the preceding claims, characterized by a push button (23) provided on the head part (2B), intended to detach the treatment tool from the clamping forceps (5), the push button (23) having an outside diameter of at least 9.0 mm.

15. Dental contra-angle (1) according to claim 14, characterized in that for differentiation of the dental contra-angle (1), the push button (23) has a marking.

16. Dental contra-angle (1) according to any one of the preceding claims taken in combination with claim 6, characterized by a maximum of three orifices (24) placed in a circle around the tool housing orifice (18), for the distribution of a cooling agent.

17. Dental contra-angle (1) according to any one of the preceding claims, characterized by a light-emitting device (25) placed on or adjacent to the head portion (2B), for distributing light onto the treatment tool and / or the treatment area.

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