WO2007104351A1

WO2007104351A1 - Toothbrush and toothbrush head for said toothbrush

Info

Publication number: WO2007104351A1
Application number: PCT/EP2006/012278
Authority: WO
Inventors: Karl Herzog
Original assignee: Braun Gmbh
Priority date: 2006-03-16
Filing date: 2006-12-20
Publication date: 2007-09-20
Also published as: HK1116639A1; AU2006339876A1; US20080209649A1; CN101175424B; DE102006012003A1; ATE535170T1; CA2608763A1; MX2007012889A; KR20080109587A; JP5269617B2; CN101175424A; EP1993398A1; EP1993398B1; JP2009529389A

Abstract

The present invention relates to a toothbrush head having a bristle support on which a bristle arrangement which has a large number of filaments is arranged, wherein at least one filament is tapered in the direction of its free end, and also to a toothbrush having a toothbrush head of this type. The invention proposes providing the tapered area at the tip of the at least one filament with a shape which deviates from a rotationally symmetrical form in order to maintain a high bending stiffness of the filament in one direction. According to the invention, the tapered area is in the form of a pressed-flat sharpened area, so that the filament has a greater bending stiffness in the region of the tapered area with respect to a first transverse axis than with respect to a second transverse axis which is at right angles to said first transverse axis. The filament cross section in the region of the pressed-flat sharpened area has a longitudinal axis or long main axis and a shorter transverse axis or short main axis, as a result of which the filament is provided with different geometric moments of inertia with respect to the two said axes in the region of the sharpened area. The pressed-flat sharpened area at the tip of the filament facilitates penetration into the interdental spaces, wherein the higher geometric moment of inertia of the broad side reduces bending here.

Description

Toothbrush and toothbrush head for this

The present invention relates to a toothbrush head having a bristle carrier on which is disposed a bristle field having a plurality of filaments, at least one filament having a taper towards its free end, and a toothbrush having such a toothbrush head.

It has been proposed for toothbrushes already a bristles whose filaments have a smaller diameter at the free end than at the base. This conical or rocket tip-shaped tapering is intended to facilitate the penetration of the filaments into the interdental spaces, in order to better clean said interdental spaces. However, the tapering of the filaments leads to a low flexural rigidity, which prevents or impedes penetration. Due to the taper, the area moment of inertia of the filaments is reduced, so that the filaments are too soft in the direction of the interdental space and can no longer penetrate into the interdental space.

JP 11-075939 shows a toothbrush bristle in which such filaments are provided with tapers towards their tip, but ultimately no truly improved penetration into the interdental spaces is ensured. In US 2005/0172436 is also proposed to provide the existing of a variety of elements bristle tufts with a tapered head by the individual filaments have a stepped length. However, this does not really facilitate penetration into the interdental space unless the individual filaments themselves have sufficient tapering or tapering at their free ends.

The present invention has for its object to provide an improved toothbrush head of the type mentioned, which avoids the disadvantages of the prior art and further develops the latter in an advantageous manner. In particular, an improved penetration of the filaments into the interdental spaces is to be achieved.

This object is achieved by a toothbrush head according to claim 1. Preferred embodiments of the invention are the subject of the dependent claims.

It is therefore proposed to give the taper at the tip of the at least one filament a shape deviating from a rotationally symmetrical shape, in order to be in one Direction to maintain a high bending stiffness of the filament. According to the invention, the taper is formed in the form of a flattened sharpening, so that the filament has a greater flexural rigidity in the region of the taper with respect to a first transverse axis than with respect to a second transverse axis perpendicular thereto. The filament cross section in the area of the flattened sharpening has a longitudinal axis or long main axis and a shorter transverse axis or short main axis, as a result of which the filament in the region of the sharpening receives different area moments of inertia with respect to the two said axes. The flattened sharpening at the tip of the filament facilitates penetration into the interdental spaces, with the higher area moment of inertia of the broad (non-tapered) side (s) reducing flexing. The flattened sharpening or sharpening of the filament is therefore limited to one side or to two opposite sides of the filament end. When flattened, reference is hereby made not to a production but to a geometric shape of the filament (as described above).

In an advantageous embodiment of the invention, the filament is sharpened wedge-shaped at its free end. The sharpening can be formed by only one inclined surface which is inclined at an acute angle to the filament longitudinal axis. Alternatively, the wedge-shaped sharpening of two opposite, mutually angled inclined inclined surfaces may be formed, so that the free end of the filament has a substantially pitched roof-shaped contour.

The at least one inclined surface, which forms the wedge-shaped sharpening of the filament, can be formed flat in the development of the invention. Alternatively, however, the inclined surface may also have a curvature, which is preferably formed uniaxial. According to an advantageous embodiment of the invention, the at least one inclined surface has a convex curvature, wherein the curvature axis can extend transversely to the filament longitudinal axis. Alternatively or additionally, the inclined surface may also be convexly curved about an axis which lies in a plane containing the filament longitudinal axis.

In a further development of the invention, the at least one inclined surface may also have a concave curvature, wherein the curvature axis in the aforementioned manner may extend transversely to the filament longitudinal axis and / or may lie in a plane containing the filament longitudinal axis. Advantageously, the flattened sharpening at the end of the filament has a rounding at its edge. In this way, despite the slight penetration into spaces a gentle tooth cleaning and avoidance of gum injuries can be achieved.

In particular, the rounding of the sharpening can be provided on the front side at the end of the filament and / or towards the side flanks. According to an advantageous embodiment of the invention, the filament may have at its free end a blunt head surface or residual surface, which passes over said rounding into the oblique surface of the sharpening. The thickness of the obtuse head surface, which is left standing from the sharpening, can in principle be dimensioned differently, depending on which sharpness is necessary and appropriate for the specific application. According to an advantageous embodiment of the invention, said blunt head surface may have a thickness of about V ₅ to ² I _{5 of} the filament diameter.

The inclination of the aforementioned inclined surfaces to one another or to the longitudinal axis of the filament can basically also be chosen differently. A favorable compromise between on the one hand a sufficient thinning, which allows penetration into the interdental spaces, and on the other hand, a sufficient remaining strength is achieved in a further development of the invention by a wedge angle of the sharpening of less than 40 °, preferably less than 30 °. According to an advantageous embodiment of the invention, a sharpening with a wedge angle in the range of 15 ° to 25 ° may be provided.

In its non-sharpened region, the at least one filament can basically have different cross-sectional shapes. According to an advantageous embodiment of the invention, the filament has a circular cross-section in the non-sharpened area.

In order not to weaken the filament too much overall, but nonetheless provide a sufficient taper, which facilitates the penetration into the interdental spaces, can be provided in development of the invention that the sharpening about about V ₈ to ⁴ / _B , preferably about ³ / ₈ , the free length of the filament extends.

Advantageously, the at least one filament is specifically aligned on the bristle carrier in such a way that the flattened sharpening can easily penetrate into the interdental spaces and the filament has its higher flexural rigidity during wiping movements in the interdental spaces, ie parallel to the tooth axis. In particular, the at least one filament can be arranged on the bristle carrier such that at - A -

Proper application of the brush head to a row of teeth with a substantially tangential orientation of the bristle carrier or toothbrush longitudinal axis to the dental arch, the longer cross-sectional main axis of the view extends parallel to the interdental space.

Depending on the design of the toothbrush or the toothbrush head, the filament can be aligned differently on the bristle carrier.

If the toothbrush head is part of a manual toothbrush, the filament is advantageously oriented in such a way that the said longer cross-sectional main axis of the sharpening extends transversely to the toothbrush longitudinal axis. If the sharpening in the aforementioned manner by two mutually inclined inclined surfaces formed, the ridge formed thereby extends between the two inclined surfaces transverse to the toothbrush longitudinal axis.

Alternatively, the toothbrush head can also be intended for an electric toothbrush. Depending on the realized movement axis, the sharpened filaments can be arranged or aligned differently. According to an advantageous embodiment of the invention, the toothbrush head with its bristle carrier can be driven in a rotationally oscillating manner about a drive axis which extends parallel to the toothbrush longitudinal axis. In this case, the at least one filament is aligned with the flattened sharpening similar to the aforementioned manual toothbrush. The longer cross-sectional main axis extends transversely to the toothbrush longitudinal axis.

Alternatively, the toothbrush head may also have a bristle carrier, which can be rotationally driven to oscillate about a transverse axis, which is approximately perpendicular to the toothbrush longitudinal axis. In this case, the at least one filament with the flattened sharpening is advantageously arranged in a sector of the bristle which is in the rotational center position of the bristle carrier approximately on the toothbrush longitudinal axis, said sector may include different angular ranges, but advantageously less than 45 °, especially less than 30 °, can be. The filaments arranged in these two sectors or angle sectors perform, when the brush head is applied as intended with an approximately tangential orientation of the bristle carrier to the dental arch, a movement which extends at least approximately in the direction of the slot-shaped interdental space. Advantageously, the filament is aligned with the longer cross-sectional main axis of its sharpening transversely to the toothbrush longitudinal axis. The bristles of the toothbrush head can basically consist of a plurality of filament tufts or bristle tufts in a manner known per se, it being possible for further wiping elements such as wiping strips, plastic wipers or elastomeric wipers to be provided, if necessary. In this case, at least one filament of at least one bristle tuft is formed in the aforementioned manner. Advantageously, the bristles comprise at least one bristle tufts, in which the plurality of filaments are formed in the aforementioned manner. Preferably, the filaments within a bristle tuft are at least approximately the same orientation, ie the longer cross-sectional major axis of the sharpening extends in the same direction in all filaments of the tuft.

In principle, various methods for forming the sharpening of the at least one filament are possible. According to a preferred embodiment of the invention, the sharpening, in particular the at least one inclined surface and / or this limiting rounding, generated by grinding the finished bristled bristle carrier.

These and other features will be apparent from the claims, as well as from the following description of preferred embodiments and the accompanying drawings, the features of which may form independent of their inclusion in the claims alone or in sub-combination with each other subject of the invention. In the drawings show:

1 is a side view of a wedge-shaped sharpened filament of a toothbrush according to a preferred embodiment of the invention,

FIG. 2 shows a side view of the filament from FIG. 1 rotated by 90 ° with respect to FIG. 1, showing an oblique surface of the sharpening in plan view, FIG.

3 shows a side view of a filament with a wedge-shaped sharpening according to a further preferred embodiment of the invention,

FIG. 4 shows a side view of the filament from FIG. 3 rotated by 90 ° with respect to FIG. 3, which shows the one oblique surface of the sharpening in plan view, FIG.

5 shows a side view of a filament with a wedge-shaped sharpening according to a further preferred embodiment of the invention, FIG. 6: a side view of the filament from FIG. 5 rotated by 90 ° relative to FIG. 5, showing the one oblique surface of the sharpening in plan view, FIG.

7 shows a side view of a filament with a wedge-shaped sharpening according to a further preferred embodiment of the invention,

FIG. 8 shows a side view of the filament from FIG. 7 rotated by 90 ° with respect to FIG. 7, which shows the one oblique surface of the sharpening in plan view, FIG.

9 shows a cross section through a mutually sharpened filament according to an advantageous embodiment of the invention, in which the oblique surfaces of the sharpening are convexly curved,

10 shows a cross section through a mutually sharpened filament according to an advantageous embodiment of the invention, in which the oblique surfaces of the sharpening are concavely curved,

11 is a plan view of a manual toothbrush with a toothbrush head according to a preferred embodiment of the invention,

12 is a plan view of an electric toothbrush with a toothbrush head according to a preferred embodiment of the invention, which is rotatably driven to oscillate about a longitudinal axis of the toothbrush, and

13 shows a plan view of an electric toothbrush with a toothbrush head according to a preferred embodiment of the invention, the bristle field of which is rotationally drivable oscillating about a transverse axis.

Figures 1 and 2 show a filament or toothbrush filament 1, which is inserted into a bristle carrier 2 of a toothbrush head, not shown in detail in Figures 1 and 2. The filament 1 has at its base a substantially circular cylindrical shape, which is sharpened double-sided towards the free end 3 of the filament 1 out. In the embodiment according to Figures 1 and 2, there is a sharpening 4 of the free end 3 of the filament 1 of two opposite, mutually acute angled inclined surfaces 5 and 6, which are flat in the illustrated embodiment. The two beveled Chen 5 and 6 include in the illustrated embodiment between them a wedge angle 7 of about 20 ° to 25 °, wherein the two inclined surfaces 5 and 6 are arranged such that forms a straight ridge at the free end 3.

The Anschärfung 4 is blunted in the illustrated embodiment at her head. The inclined surfaces 5 and 6 are not completely merged at the free end 3 to a mathematical line, but still slightly spaced apart, so that forms a blunt, ungühr rectangular top surface 8.

As FIG. 1 shows, a bevel 12 is provided at the front edge of the inclined surfaces 5 and 6, via which the inclined surfaces 5 and 6 merge into the blunt head surface 8. The rounding 12 follows the entire outer contour of the inclined surfaces 5,6.

The scarfing 4 is designed in total in such a way that it extends over a length 10 which is about ^_3/8 of the total length of the filament 1 in the embodiment drawn. 11 A thickness 9 of the blunt head surface 8 is about% of the filament diameter in the illustrated embodiment.

As an alternative to the embodiment shown in FIGS. 1 and 2, the sharpening 4 of the filament 1 can also be formed by a single oblique surface 5 which also extends at an acute angle to the longitudinal axis of the respective filament 1, as shown in FIGS. 3 and 4. In this case, the oblique surface 5 is advantageously less sharply inclined with respect to the filament longitudinal axis than with a double-sided sharpening. The angle of inclination of the inclined surface 5 is approximately 25 ° in the embodiment shown in FIG. 3, so that the sharpening 4 in turn has a total wedge angle 7 of approximately 25 °. Also in the case of the embodiment shown in FIGS. 3 and 4, the oblique surface 5 is planar, so that, together with the circular-cylindrical basic shape of the filament 1, an elliptical shape of the oblique surface 5 results, as FIG. 4 shows.

Advantageously, the end edge of the inclined surface 5 is rounded in the embodiment according to Figures 3 and 4. About the rounding 12, the inclined surface 5 is also in the embodiment of Figures 3 and 4 in the blunt head surface 8 via. The arrangement of the inclined surface 5 is here also made such that the Anschärfung 4 extends over the entire length 10, which is about% of the total length 11 of the filament 1, and that the thickness 9 of the obtuse head surface 8 about ^Λ A of the total thickness of the Filaments is 1. The embodiment shown in Figures 5 and 6 substantially corresponds to the embodiment shown in Figures 1 and 2, wherein the inclined surfaces 5 and 6 are not flat here, but have a concave curvature about an axis transverse to the filament longitudinal axis. As FIG. 5 shows, the wedge angle 7 thus decreases between the oblique surfaces 5 and 6 towards the free end 3 of the filament 1. However, it is also advantageously in the range of less than 40 °, preferably between 15 ° and 35 °.

The embodiment of Figures 7 and 8 also corresponds in principle to the double-sided sharpening according to the embodiment of Figures 1 and 2, wherein the inclined surfaces 5 and 6 here, however, have a convex curvature, namely about a curvature axis transverse to the filament longitudinal axis, so that the wedge angle 7 increases gradually between the inclined surfaces 5 and 6 towards the free end 3 of the filament. It is advantageously also between 15 ° and 35 °.

Alternatively or additionally, the inclined surfaces 5 and 6 may also have a convex or concave curvature about a curvature axis extending in a plane containing the filament longitudinal axis. FIG. 9 shows such a convex curvature, while FIG. 10 shows a corresponding concave curvature of the inclined surfaces 5 and 6.

The sharpening 4 and the rounding 12 can be produced by grinding the filaments of the finished bristled bristle carrier 2.

The filaments 1 shown in FIGS. 1 to 10 have in common that the sharpening 4 is substantially wedge-shaped and the filaments 1 in the region of the sharpening 4 have different area moments of inertia relative to mutually perpendicular or perpendicular axes. The flexural rigidity of the filament 1 is greater in one direction 13 of the longer cross-sectional main axis (compare Figures 2, 4, 6 and 8) than in the direction of the shorter cross-sectional major axis of the sharpening 4. In other words, this means that the filament 1 stiffer when bending it parallel to the bevels 5 and 6 of the sharpening, while it is less stiff when bending it at right angles to the inclined surfaces 5 and 6.

Advantageously, the filaments 1 are oriented such that the direction 13 of the longer cross-sectional major axis extends parallel to the slot-shaped interdental spaces when the toothbrush is placed on the dental arch as intended. As 11 shows, the filaments 1 can be combined into bristle tufts 14, which together form a bristle field 15 which is arranged on the bristle carrier 12 of a toothbrush head 17. If the toothbrush head 17 is part of a manual toothbrush, as shown in FIG. 11, the filaments 1, with their longer cross-sectional main axis extending in the direction 13, are aligned transversely to the toothbrush longitudinal axis.

The same applies if the toothbrush head 17 is intended for an electric toothbrush, in which the bristle carrier 2 is rotationally driven to oscillate about a drive axis 18 which extends parallel to the toothbrush longitudinal axis, as FIG. 12 shows. The rotationally oscillating movement about the drive axis 18 illustrates an arrow 19. Advantageously, the filaments 1 are aligned with their longer cross-sectional main axis in the direction 13 transversely to the toothbrush longitudinal axis and thus transversely to the drive axis 18.

In the electric toothbrush shown in Figure 13, the bristle carrier 2 is formed substantially disc-shaped or oval and about the drive axis 18 rotationally drivable. The drive shaft 18 is approximately at right angles to the toothbrush longitudinal axis. In this case, advantageously only the filaments 1 of some bristle tufts are sharpened in the aforementioned manner. In particular, these may be bristle tufts 20 and 21 arranged in angular sectors 22 and 23 of the approximately total cylindrical or e.g. oval bristle field 15 are located in the rotational center position of the bristle carrier 2 on the toothbrush longitudinal axis and are arranged symmetrically to this. Said sectors 22 and 23 can cover different angular ranges, in the illustrated embodiment about 30 ° each. The bristle tufts 20 and 21 lying in the sectors 22 and 23 at the edge of the bristle field 15 perform a movement which extends approximately parallel to the slot-shaped interdental spaces. Advantageously, the filaments 1 are also aligned transversely to the toothbrush longitudinal axis with their longer cross-sectional main axes in the direction of the arrow 13 when the bristle carrier 2 is in its rotational center position.

An advantageous development relates to the oppositely disposed sectors 24 and 25, which form the bristle field 15 optionally additionally in a special education in addition to the sectors 22 and 23. In the sectors 24 and 25, the filaments 1 are arranged in bristle tufts 26 and 27 so that the longer cross-sectional major axis of the sharpening 4 is in the direction of the arrow 13 transverse to the toothbrush longitudinal axis. All filaments 1 in the bristle field 15 are thus aligned parallel with their sharpening 4. Does that Borstenfeld 15, the rotationally oscillating drive movement according to arrow 19, so is the direction of movement of the filaments 1 of the tufts 26 and 27 in the sectors 24 and 25 approximately transverse to the shorter cross-sectional main axis of Anschärfung 4. This means that the filaments 1 of the bristle tufts 26 and 27 In the area of the sharpening 4, there is little resistance to bending. The filaments 1 are thus flexible in the sectors 24 and 25, in which they touch the gums when cleaning. This hinders injury to the gums.

An advantage of the parallel alignment of the sharpening 4 in all the filaments 1 of a bristle field 15 is the simplified production, for example, if the sharpening 4 is simultaneously ground in all the filaments 1.

Claims

claims

A toothbrush head with a bristle carrier (2) on which a bristle field (15) is arranged, which has a plurality of filaments (1), wherein at least one filament (1) has a taper at its free end (3), characterized in that the taper is in the form of a flattened sharpening (4), so that the filament (1) has a greater flexural rigidity in the region of the taper with respect to a first transverse axis than with respect to a second transverse axis perpendicular thereto.

2. Toothbrush head according to the preceding claim, wherein the Anschärfung (4) is wedge-shaped.

3. Toothbrush head according to one of the preceding claims, wherein the at least one filament (1) is aligned on the bristle carrier (2), that upon proper application of the brush head on a row of teeth with approximately tangential alignment of the toothbrush longitudinal axis to the dental arch, the longer cross-sectional major axis of Anschärfung (4) extends approximately parallel to the slot-shaped interdental spaces.

4. Toothbrush head according to one of the preceding claims, wherein the at least one filament (1) on the bristle carrier (2) is aligned, that when intended application of the brush head on a row of teeth with approximately tangential alignment of the toothbrush longitudinal axis to the dental arch, the higher bending stiffness in terms of cleaning movements parallel given to the interdental spaces.

5. Toothbrush head according to one of the preceding claims, wherein the sharpening (4) of an acute axis inclined to the filament oblique inclined surface (5) is formed.

6. Toothbrush head according to one of claims 1 to 4, wherein the Anschärfung (4) of two opposite, each acute angle inclined to the filament longitudinal inclined surfaces (5, 6) is formed.

7. toothbrush head according to one of the two preceding claims, wherein the inclined surface (5) or the inclined surfaces (5, 6) is flat or are.

8. Toothbrush head according to one of claims 5 or 6, wherein at least one inclined surface (5, 6) has a curvature.

9. Toothbrush head according to the preceding claim, wherein the curvature is uniaxial.

10. Toothbrush head according to one of the two preceding claims, wherein the curvature is convex.

11. Toothbrush head according to one of claims 7 to 9, wherein the curvature is concave.

12. Toothbrush head according to one of the preceding claims, wherein the Anschärf ung (4) at its edge at least to the free end (3) of the filament (1) out a rounding (12).

13. Toothbrush head according to claim 12, characterized in that the rounding (12) of the entire outer contour of the inclined surfaces (5, 6) follows.

14. Toothbrush head according to one of the preceding claims, wherein the sharpening (4) has a blunt head surface (8).

15. Toothbrush head according to the preceding claim, wherein the blunt head surface (8) has a thickness of about V ₅ to ² I _{5 of} the filament diameter.

16. Toothbrush head according to one of the preceding claims, wherein the sharpening (4) has a wedge angle (7) of less than 40 °, preferably less than 30 °.

17. Toothbrush head according to the preceding claim, wherein the wedge angle (7) is between 15 ° and 25 °.

18. Toothbrush head according to one of the preceding claims, wherein the filament (1) has a circular cylindrical contour in its not sharpened area.

19. A toothbrush head according to any one of the preceding claims, wherein the scarfing (4) extends over about ^_1/8 bis ^_4/8, preferably about ^_3/8, of the free length (11) of the filament (1).

20. Toothbrush head according to one of the preceding claims, wherein the sharpening (4) can be generated by grinding.

21. Toothbrush head according to one of the preceding claims, wherein it is designed as a manual toothbrush head.

22. Toothbrush head according to one of claims 1 to 20, wherein it is designed as Elektrozahnbürs- tenkopf and the bristle carrier (2) about a drive axis (18) parallel to the toothbrush longitudinal axis rotationally driven in rotation.

23. Toothbrush head according to one of the two preceding claims, wherein the at least one filament (1) with the longer cross-sectional main axis of the sharpening (4) is aligned transversely to the toothbrush longitudinal axis.

24. Toothbrush head according to one of claims 1 to 20, wherein it is designed as Elektrozahnbürs- tenkopf and the bristle carrier (2) about a drive axis (18) transverse to the toothbrush longitudinal axis rotationally driven to drive.

25. Toothbrush head according to the preceding claim, wherein the at least one filament (1) in one or two opposite angular sectors (22, 23) is arranged, containing the toothbrush longitudinal axis in a rotational center position of the bristle carrier (2) and are arranged symmetrically to the toothbrush longitudinal axis wherein the at least one filament 1 is aligned in the said rotary central position of the bristle carrier (2) with its longer cross-sectional main axis transverse to the toothbrush longitudinal axis.

26. A toothbrush head according to the preceding claim, wherein the angular sectors (22, 23) include an angular range of less than 45 °, preferably less than 30 °.

27. Toothbrush head according to the preceding claims 24 to 26, wherein the at least one filament (1) in two opposite angular sectors (24, 25) is arranged, which lie on an axis in the rotational center position of the bristle carrier (2) at right angles to the toothbrush longitudinal axis stands, wherein the at least one filament (1) in the said rotational center position of the bristle carrier (2) is aligned with its longer cross-sectional major axis transverse to the toothbrush longitudinal axis.

28. Toothbrush head according to one of the preceding claims, wherein the filaments (1) to bristle tufts (14, 20, 21, 26, 27) are arranged in a group on the bristle carrier (2), wherein in a bristle tufts (14, 20, 21, 26 , 27) containing filaments (1) with flattened sharpenings (4), at least ³ A of all filaments (1) with purchases (4), preferably all filaments (1) in the same bristle tufts (14, 20, 21, 26, 27 ) have the same orientation.

29. Toothbrush head according to one of the preceding claims, wherein the sharpening (4) is formed such that the bending stiffness of the filament (1) with respect to the first transverse axis by at least 20%, preferably more than 35%, is greater than the bending stiffness with respect to the second transverse axis.

30. Toothbrush with a toothbrush head according to one of the preceding claims.