CA3222206A1

CA3222206A1 - Interdental brush having an oval wire cross section, and method for producing the same

Info

Publication number: CA3222206A1
Application number: CA3222206A
Authority: CA
Inventors: Marco ZAVALLONI
Original assignee: CURADEN AG
Current assignee: CURADEN AG
Priority date: 2021-06-02
Filing date: 2022-06-02
Publication date: 2022-12-08
Also published as: WO2022253977A1; BR112023024919A2; JP2024520133A; EP4346504A1; US20240245206A1; KR20240023028A

Abstract

The present invention relates to an interdental brush (1, 1') having a brush part (2) that comprises two twisted-together legs (4A, 4B) of a wire portion (4) and brush filaments (5) held clamped between the legs (4A, 4B), and to a method for producing such an interdental brush (1, 1'). In order to improve in particular the bend fatigue limit of the wire portion (4), according to the invention a wire portion (4) made of austenitic steel is used that has a chromium content of 15 to 17 wt.%, a manganese content of 12 to 16 wt.% and a molybdenum content of 0 to 4 wt.%, and the wire portion (4) is formed having an oval cross section with an ovality O in a range between 0.4 and 0.9, wherein the ovality O is measured as a ratio between a length (LQk) of a small transverse axis (Qk) and a length of a large transverse axis (Qg) of the cross section.

Description

INTERDENTAL BRUSH HAVING AN OVAL WIRE CROSS SECTION, AND METHOD FOR
PRODUCING THE SAME
Technical field The present invention relates to an interdental brush having a brush part comprising two twisted-together legs of a wire section and brush filaments held clamped between the legs.
Further, the invention relates to a method for producing such an interdental brush.
Prior art Interdental brushes are known from the prior art. They usually comprise a handle part or a part for fixing the interdental brush to a handle and the brush part attached to the handle part or part for fixing for cleaning interdental spaces. For producing interdental brushes, the brush filaments are held extending transversely to the legs of the wire section between the legs and then twisted together with them to be clamped therebetween, whereby an outer contour of the brush part assumes a spiral shape.
For example, DE 10 2018 101 085 Al relates to a twisted-in brush with a bristle support comprising wire sections twisted together, which comprise oval and/or elliptical cross sections at least in the distal section of the bristle support. Furthermore, a twisted-in brush is also proposed, the bristle support of which comprises an anti-extraction device at a distance from its proximal end. With the aid of this pull-out safety device, the bristle support can be fixed to the handle of the screw-in brush in a pull-out-proof manner. Furthermore, a method for producing a twisted-in brush is also proposed, in which wire sections, at least one of which is profiled, i.e.
Date Recue/Date Received 2023-12-01

2 comprises at least two regions with different cross sections, are twisted together to form the bristle support.
EP 1 470 765 B1 of the applicant relates to an interdental brush in which filaments or bristles are held between two twisted wire sections consisting of an austenitic steel, and a method for producing such brushes. These are characterized by good stiffness with a relatively small diameter of the wire section.
In the case of interdental brushes known from the prior art, it has been found in practice to be a disadvantage that the brushes tend to break prematurely, in particular in the transition region between the brush part and the handle part, where the wire section is subjected to frequent bending changes when it is guided into the interdental spaces at different frequently changing angles between the handle part and the brush part.
Description of the invention The object of the invention is to reduce the disadvantages encountered in interdental brushes known from the prior art. In particular, it is an object of the present invention to improve the flexural fatigue strength of the wire section.
.. These objects are solved by an interdental brush as described herein.
In particular, these objects are solved in an interdental brush having a brush part comprising two twisted-together legs of a wire section and brush filaments held clamped between the legs, in that the wire section consists of an austenitic steel having a chromium content of 15 to 17 wt. % by weight, a manganese content of 12 to 16 % by weight, a molybdenum content of 0 to 4 % by weight, and an oval cross-section having an ovality 0 in a range between 0.4 to 0.9, wherein the ovality 0 is dimensioned as a ratio between a length of a small transverse axis to a length of a large transverse axis of the cross-section.
Date Recue/Date Received 2023-12-01

3 In a method for producing interdental brushes according to the invention, these objects are solved in particular by twisting together two legs of a wire section and clamping brush filaments held between the legs to produce a brush part of the interdental brush, wherein a wire section made of an austenitic steel is used which has a chromium content of 15 to 17 wt.%, a manganese content of 12 to 16 wt.% and a molybdenum content of 0 to 4 wt.%. %, a manganese content of 12 to 16 wt.% and a molybdenum content of 0 to 4 wt.%, and wherein the wire section is formed with an oval cross-section having an ovality 0 in a range between 0.4 to 0.9, and wherein the ovality 0 is dimensioned as a ratio between a length of a small transverse axis to a length of a large transverse axis of the cross-section.
The solution according to the invention has the advantage that the selected alloy provides a particularly tough yet sufficiently stiff steel in which the flexural fatigue strength is particularly good. The fatigue strength is also improved by the selected ovality, especially in the transition area between the brush part and the handle part, where the wire section is subjected to frequent bending cycles. Thus, according to the invention, particularly durable dental brushes are provided which permit frequent bending changes and can therefore be used flexibly over the long term.
The solution according to the invention can be supplemented and improved as desired by the following further embodiments, each of which is advantageous in itself, whereby a person skilled in the art will clearly and unambiguously recognize of his own accord and without further ado that product features of an interdental brush according to the invention analogously represent in each case steps of a method according to the invention and vice versa:
According to a further embodiment according to the invention, the twisted legs comprise turns with a turn length measured parallel to a longitudinal axis of the brush which is smaller than 1.5 times a maximum outer diameter of the wire section. A length of an untwisted limb measured parallel to the brush longitudinal axis can exceed a length of the twisted limb measured parallel to the brush longitudinal axis by a factor of 1.6 to 2.4, preferably by a factor of 1.8 to 2.2, most preferably by a factor of 2. Thus, particularly tightly twisted brush parts can be provided. Dense twisting helps, on the one hand, to generally increase the density or quantity of brush filaments Date Recue/Date Received 2023-12-01

4 that can be clamped between the legs. On the other hand, dense twisting helps to further improve the flexural strength and elasticity of the brush section by increasing spring forces.
According to a further embodiment according to the invention, it is provided that a depth of the turns measured as the difference between the maximum outer diameter and a minimum inner diameter is less than 0.05 to 0.2 times, preferably 0.075 to 0.15 times, most preferably 0.1 times the maximum outer diameter. A particularly shallow depth of the turns helps to further increase the density and compactness of the brush part, thus further improving its flexural strength and elasticity. In addition, a particularly shallow depth of the turns causes a reduction in the surface area and smoothing of the brush part, whereby deposits of dirt and bacteria can be reduced there.
According to another embodiment in accordance with the invention, it is provided that the wire comprises an elliptical original cross-section, wherein a ratio of a length of a major semi-axis of the ellipse to a length of a minor semi-axis of the ellipse is between 1.4 and 1.6. Such an elliptical cross-section of the wire by itself helps to further improve the flexural strength and elasticity of the brush part. Also, the elliptical cross-sectional shape of the wire can reduce the depth of the turns of the brush part or a seam formed between the legs thereof, which, in addition to increasing the flexural strength and elasticity, can also reduce the surface area of the brush part and smooth it, which in turn helps to further reduce deposits of contaminants and bacteria.
According to a further embodiment in accordance with the invention, it is provided that the ratio of the length of the major semi-axis of the ellipse to the length of the minor semi-axis of the ellipse is between 1.5 and 1.55. For example, the ratio of the length of the large semi-axis of the ellipse to the length of the small semi-axis of the ellipse may be substantially 1.53. Thus, the advantages already mentioned above of improving the flexural strength and elasticity of the brush part, on the one hand, and reducing its surface area and smoothing it, on the other hand, can be further improved.
It is also conceivable that the wire section is provided with a coating. A
coating thickness of the coating may be substantially half a thickness of the brush filaments. The brush filaments may be embedded in the coating. The coating and embedding help to further smooth and reduce the surface area of the brush part and to close any pores, capillaries, and other openings between Date Recue/Date Received 2023-12-01 the twisted legs of the wire section or between the brush filaments. Thus, deposits of contaminants and bacteria can be further reduced.
According to a further embodiment according to the invention, it is provided that a number of brush filaments per turn is greater than 10. Advantageously, the number of brush filaments per

5 turn can be greater than 25. A number of 40 to 60, for example about 50 brush filaments per turn can be considered highly advantageous. Thus, a particularly high density of brush filaments can be achieved, which are arranged spirally along the brush part adjacent to one another and/or overlapping as closely as possible. This helps to further improve the cleaning effect and ease of use of an interdental brush according to the invention.
According to a further embodiment according to the invention, it is provided that a useful length of the brush filaments measured transversely to the longitudinal axis of the brush between an outer contour of the twisted wire section and a free end of the brush filaments is between 4 to 5 times the maximum outer diameter. Thus, the ratio of a volume of the interdental brush occupied by a contour of the brush filaments in its entirety far exceeds a volume occupied by the wire section. This helps to further improve the cleaning effect and convenience of use of an interdental brush according to the invention.
According to a further embodiment according to the invention, it is provided that a ratio between the maximum outer diameter and/or a maximum wire diameter of the wire and a maximum filament diameter of the brush filaments is between 4 and 4.6. Such a ratio leads to an improved matching between elasticity and stiffness of the wire section on the one hand and the brush filaments on the other hand. Thus, user comfort and longevity of an interdental brush according to the invention can be further increased.
According to a further embodiment according to the invention, it is provided that a free brush end comprises a rounding and that a maximum rounding diameter of the rounding is larger than the maximum outer diameter. For example, the free brush end is spherical in shape, at least in sections. The rounding helps to avoid or at least reduce sharp edges and corners at the free brush end. Thus, a risk of injury is reduced and the comfort of use is further increased.
Date Recue/Date Received 2023-12-01

6 According to another embodiment in accordance with the invention, the austenitic steel is provided to comprise a nitrogen content of 0.5 wt.%, a silicon content of 0.25 wt.%, a carbon content of 0.11 wt.% and a nickel content of less than 0.05 wt.%. Such an alloy further helps to provide a particularly tough and sufficiently stiff steel with particularly good flexural fatigue strength. Furthermore, a very low nickel content of less than 0.05 wt.% is helpful in providing interdental brushes according to the invention with the highest possible biocompatibility.
In a method for producing an interdental brush, the solution according to the invention can be further improved by stretching the brush part along the longitudinal axis of the brush after twisting. For example, a stretch ratio between a stretched length and an unstretched length of the brush part may be greater than 1 to 1.2, preferably greater than 1.05 to 1.15, most preferably 1.1. Thus, density, elasticity and flexural fatigue strength of the brush part can be further increased.
From the following detailed description and the totality of the patent claims, further advantageous embodiments and combinations of features of the invention can be derived.
Brief description of the drawings For a better understanding of the present invention, reference is made in the following to the drawings enclosed herewith. These merely show possible examples of embodiments of the object of the invention, whereby its features, as described above, can be combined with one another or omitted as desired according to the respective requirements.
It shows:
Fig. 1 a schematic perspective view of an interdental brush according to the invention;
Fig. 2 a schematic side view of a brush part of the interdental brush shown in Fig. 1;
Fig. 3 a schematic cross-sectional view of an untwisted wire section of the interdental brush shown in Figs. 1 and 2;
Date Recue/Date Received 2023-12-01

7 Fig. 4 a schematic cross-sectional view of a brush filament of the interdental brush shown in Figs. 1 to 3;
Fig. 5 a schematic side view of a brush part of a further embodiment of an interdental brush according to the invention;
Fig. 6 a schematic cross-sectional view of an untwisted wire section of the interdental brush shown in Fig. 5;
Fig. 7 a schematic cross-sectional view of a brush filament of the interdental brush shown in Figs. 5 and 6;
Fig. 8 a schematic side view of a detail of an interdental brush according to the invention;
Fig. 9 a schematic cross-sectional view of the interdental brush shown in Fig. 8 along the line of intersection A-A drawn in Fig. 8;
Fig. 10 a schematic cross-sectional view of twisted wire sections of an interdental brush according to the invention; and Fig. 11 a schematic perspective view of a device for measuring buckling resistance forces of interdental brushes according to the invention.
Ways to carry out the invention Fig. 1 shows a schematic perspective view of an interdental brush 1 according to the invention with a brush part 2 and a handle part 3, which is accommodated in a handling device 3A. The brush part 2 comprises a wire section 4 to which brush filaments 5 are held.
At least brush part 2 and handle part 3 extend substantially parallel to a longitudinal brush axis L of the interdental brush 1.
Date Recue/Date Received 2023-12-01

8 Fig. 2 shows a schematic side view of the brush part 2 of the interdental brush 1 shown in Fig. 1.
Here it is clear that the brush filaments 5 extend radially away from the wire section 4, running essentially perpendicular to the longitudinal axis L of the brush. At the same time, the brush filaments 5 together form a kind of spiral winding around the wire section 4.
An outer diameter DB of the brush part 2 measured transversely to the longitudinal axis of the brush is approximately 2.5 mm in the embodiment example of the interdental brush 1 shown in Fig. 2.
Fig. 3 shows a schematic cross-sectional view of a wire section 4A, 4B of the interdental brush 1 shown in Figs. 1 and 2 in an untwisted state U. The untwisted wire section 4A, 4B of the interdental brush 1 has an elliptical cross-sectional shape. In the present embodiment example, a major semi-axis of the ellipse has a length LHg of about 0.26 mm, while a minor semi-axis of the ellipse has a length LHk of about 0.17 mm.
Fig. 4 shows a schematic cross-sectional view of one of the brush filaments 5 of the interdental brush 1 shown in Figs. 1 to 3. In the present embodiment, the brush filament 5 has a cross-section with a filament diameter DF of approximately 0.0635 mm.
Fig. 5 shows a schematic side view of a brush part 4 of a further embodiment of an interdental brush 1 according to the invention. Here it is again clear that the brush filaments 5 extend radially away from the wire section 4, running essentially perpendicular to the longitudinal axis L of the brush. At the same time, the brush filaments 5 together form a kind of helix or helix winding around the wire section 4. An outer diameter DB of the brush part 2 measured transversely to the longitudinal axis of the brush is approximately 2.2 mm in the embodiment example of the interdental brush 1' shown in Fig. 5.
Fig. 6 shows a schematic cross-sectional view of the wire section 4A, 4B of the interdental brush 1' shown in Fig. 5 in the untwisted state U. The untwisted wire section 4A, 4B
of the interdental brush 1' also has an elliptical cross-sectional shape. In the present embodiment example, a large half-axis of the ellipse has a length LHg of about 0.23 mm, while a small half-axis of the ellipse has a length LH k of about 0.15 mm.
Date Recue/Date Received 2023-12-01

9 Fig. 7 shows a schematic cross-sectional view of a brush filament 5 of the interdental brush 1' shown in Figs. 5 and 6. In the present embodiment example, the brush filament 5 has a cross-section with a filament diameter DF of approx. 0.0508 mm.
Fig. 8 shows a schematic side view of a detail of the interdental brush 1, 1 according to the invention. The wire section 4 is in a twisted state V with its legs 4A, 4B, in which the legs 4A, 4B
together with brush filaments 5 held clamped between them wind spirally about the longitudinal axis L of the brush. In the present embodiment, a turn length S of the turns measured substantially parallel to the brush longitudinal axis L is smaller than 1.5 times a maximum outer diameter DD of the wire section 4.
Furthermore, the brush filaments 5 have a useful length LN with which they extend radially away from the wire section 4 in the twisted state V. measured essentially perpendicularly to the longitudinal axis L of the brush. Advantageously, the useful length LN is between 3.8 and 16 times the maximum outer diameter DD of the wire section 4. Preferably, the useful length LN is between 4 and 10 times the maximum wire diameter. Furthermore, a free brush end 6 is provided with a rounding 7, which is formed, for example, by upsetting and/or other plastic deformation, preferably as cold deformation, in order not to damage the brush filaments, which are generally made of a synthetic material.
Fig. 9 shows a schematic cross-sectional view of the interdental brush 1, 1' shown in Fig. 8 along the section line A-A drawn in Fig. 8. Here it is clear that the rounding comprises a rounding diameter DA measured perpendicular to the longitudinal axis L of the brush, which exceeds the maximum outer diameter DD of the wire section 4. A seam 8 formed between the legs 4A, 4B in the twisted state V has a depth T measured perpendicular to the brush longitudinal axis L, which is a difference between the maximum wire diameter DD and a minimum diameter or inner diameter Di of the wire section 4 measured at the bottom of the seam 8.
Fig. 10 shows a schematic cross-sectional view of the legs 4A, 4B of the interdental brush 1, 1' in the twisted state V. Here it is clear that the legs 4A, 4B each comprise an oval cross-section with a large transverse axis Qg and a small transverse axis Qg with a length LQg and LQk respectively. An ovality 0 of the cross section, measured as the ratio between the length LQk of Date Recue/Date Received 2023-12-01 the small transverse axis Qk to the length LQg of the large transverse axis Qg, is preferably between 0.4 and 0.9.
Fig. 11 shows a schematic perspective view of a device 100 for measuring buckling resistance forces FW of the interdental brush 1, 1'. The interdental brush 1, 1' is held fixed with its handle 5 part 3A in a holder (not shown), which in turn is movable relative to the device 100 in a direction substantially parallel to the longitudinal axis L of the brush. The device comprises a punch 101, a receiving plate 102 and two clamping jaws 103A, 103B. The plunger 101 is fixed in a received manner in the receiving plate 102. The receiving plate 102 is held clamped between the clamping jaws 103A, 103B.

10 The free brush end 6 rests on top of the plunger 101. With the aid of the plunger 102 and/or the receiving plate 102, a buckling force FK directed substantially parallel to the brush longitudinal axis L and acting on the free brush end 6 can be measured, which is counteracted by a buckling resistance force FW applied by the interdental brush 1, 1 or its brush part 2 when the interdental brush 1, 1' is moved in the direction of the device 100. If the buckling force FK exceeds the buckling resistance force FW, the wire section 4 of the brush part 2 buckles.
The buckling resistance force FW can be used as an indicator for the flexural fatigue strength of the interdental brushes 1, 1' or their wire section 4. The buckling resistance force FW and the flexural fatigue strength should generally be proportional to each other. In other words, the higher the buckling resistance force FW, the higher the bending fatigue strength of the wire section 4.
Buckling tests carried out with the device 100 have shown that interdental brushes 1, 1' according to the invention produced from wires with an elliptical original cross-section apply significantly higher buckling resistance forces FW than interdental brushes produced according to the prior art from wires with round cross-sections. For example, interdental brushes 1, 1' according to the invention, which are produced from an elliptical wire, the cross-section of which has a small semi-axis with a length LHk of 0.15 mm and a large semi-axis with a length LHg of 0.25 mm, produce buckling resistance forces FW of 2.52 Newton on average, with a measured minimum value of 2.17 Newton, a measured maximum value of 2.69 Newton and a standard deviation of 0.19 Newton. In contrast, with a wire diameter of 0.18 mm from the wire cross-Date Recue/Date Received 2023-12-01

11 sectional area, comparable interdental brushes with a round wire cross-section according to the prior art only generate buckling resistance forces FW of 1.63 Newton on average with a measured minimum value of 1.58 Newton, a measured maximum value of 1.70 Newton and a standard deviation of 0.05 Newton. Consequently, interdental brushes 1, 1 according to the invention are clearly superior to interdental brushes according to the prior art in terms of the buckling resistance forces FW applied by them and therefore also in terms of their flexural fatigue strength.
Modifications of the above-described examples are possible within the scope of the invention.
Date Recue/Date Received 2023-12-01

Claims

CLAIMS:

1. Interdental brush with a brush part comprising two twisted-together legs of a wire section and brush filaments held clamped between the legs wherein the wire section is made of an austenitic steel having a chromium content of 15 to 17 wt.%, a manganese content of 12 to 16 wt.%, a molybdenum content of 0 to 4 wt.%, and comprises an oval cross-section having an ovality in a range between 0.4 to 0.9, wherein the ovality is dimensioned as a ratio between a length of a small transverse axis to a length of a large transverse axis of the cross-section, and a wire of the wire section comprises an elliptical origin cross-section, wherein a ratio of a length of a major semi-axis of the ellipse to a length of a minor semi-axis of the ellipse is between 1.4 and 1.6.

2. Interdental brush according to claim 1, wherein the twisted legs comprise turns having a turn length, measured parallel to a longitudinal axis of the brush, which is smaller than 1.5 times a maximum outer diameter of the wire section.

3. Interdental brush according to claim 1, wherein a depth of the turns measured as a difference between the maximum outer diameter and a minimum inner diameter is smaller than 0.05 to 0.2 times the maximum outer diameter.

4. Interdental brush according to claim 1, wherein the ratio of the length of the major semi-axis of the ellipse to the length of the minor semi-axis of the ellipse is between 1.5 and 1.55.

5. Interdental brush according to claim 1, wherein a number of brush filaments per turn is greater than 10.

6. Interdental brush according to claim 1, wherein a useful length of the brush filaments measured transversely to the longitudinal axis of the brush between an outer contour of the twisted wire section and a free end of the brush filaments is between 3.8 and 16 times the maximum outer diameter.

7. lnterdental brush according to claim 1, wherein a ratio between the maximum outer diameter and/or a maximum wire diameter of the wire and a maximum filament diameter of the brush filaments is between 4 and 4.6.

8. Interdental brush according to claim 1, wherein a free brush end comprises a rounding and a maximum rounding diameter of the rounding is larger than the maximum outer diameter.

9. lnterdental brush according to claim 1, wherein the austenitic steel comprises a nitrogen content of 0.5 wt.%, a silicon content of 0.25 wt.%, a carbon content of 0.11 wt.% and a nickel content of less than 0.05 wt.%.

10. Method for producing an interdental brush, wherein for producing a brush part of the interdental brush two legs of a wire section are twisted together and brush filaments held between the legs are clamped, wherein a wire section made of an austenitic steel comprising a chromium content of 15 to 17 wt.%, a manganese content of 12 to 16 wt.% and a molybdenum content of 0 to 4 wt.% is used, and the wire section is formed with an oval cross section having an oyality in a range between 0.4 to 0.9, the oyality being dimensioned as a ratio between a length of a small transverse axis to a length of a large transverse axis of the cross section.

11. Method according to claim 10, wherein the brush part is stretched along the longitudinal axis of the brush after twisting.