Abstract:
An interdental brush ( 10 ) for cleaning gaps between teeth and/or dental implants includes a brush head ( 11, 19, 22 ) which has a longitudinal bristle carrier ( 13, 20 ) and a plurality of bristles ( 16, 23 ). The bristles ( 16, 23 ) extend away from the bristle carrier ( 13, 10 ) in a radially outward manner. To ease cleaning of the gaps between teeth and/or a dental implant, in particular to reduce the risk of injury when using an interdental brush ( 10 ), the brush head ( 11, 19, 22 ) of the interdental brush ( 10 ) is embodied as a single-component injection molded part.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a United States National Phase Application of International Application PCT/EP2015/052447 filed Feb. 5, 2015 and claims the benefit of priority under 35 U.S.C. §119 of German Applications 10 2014 001 502.5 filed Feb. 6, 2014 and 10 2014 001 503.3 filed Feb. 6, 2014 the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention pertains to an interdental brush for cleaning interdental spaces and/or dental implants, with a brush head, which has an elongated bristle carrier and a plurality of bristles, wherein the bristles extend away from the bristle carrier in a radially outward manner. 
       BACKGROUND OF THE INVENTION 
       [0003]    Such an interdental brush is known from US 2009/0235477 A1. The bristle carrier is configured in this prior-art interdental brush as a metal wire or as a metal core. 
         [0004]    It is disadvantageous in this case that the metallic bristle carrier or the metal core may cause injuries to the gums and/or the dental enamel, for example, due to cuts or punctures. Furthermore, there is a risk that dental implants will be scratched because of the metallic bristle carrier. Injuries in the oral region lead to the risk of colonization with microorganisms and inflammations, which may lead, for example, even to peri-implantitis, bone loss and/or loss of tooth, especially the loss of an implant as a consequence. To minimize these risks, intensive training of the patient is necessary, so that he will be able to use the prior-art interdental brush as expertly as possible. However, such an intensive training is not carried out, as a rule, for time and cost reasons, for example, in a dental practice. Moreover, interdental brushes are often used several times. This implies the risk of spreading microorganisms, especially because of a surface having pronounced hollow spaces in case of usual metal cores. In addition, there is a risk that a metal core, especially also a coated metal core, will undergo oxidation and/or rusting because of storage and/or cleaning in a solution, especially a chlorhexidine solution. 
         [0005]    Furthermore, an interdental toothpick is known from DE 10 2011 101 391 A1. This toothpick is manufactured as a two-component injection-molded part. As a result, the manufacturing process is complicated, which leads to increased costs. Moreover, it is disadvantageous in the case of the prior-art toothpick that it has only a small number of laterally projecting elevations and in only a small number of different directions. Further, it is disadvantageous that the cleaning area is limited in an interdental space, especially in a region of the neck of a tooth, due to the predefined wedge shape of the toothpick. In addition, the length of the toothpick does not usually make it possible to use it from the lingual and/or palatine area in the buccal direction. 
       SUMMARY OF THE INVENTION 
       [0006]    A basic object of the present invention is to perfect an interdental brush of the type mentioned in the introduction such that cleaning of the interdental space and/or implant is facilitated; in particular, the risk of injury and/or damage during the use of an interdental brush shall be reduced. 
         [0007]    This basic object of the present invention is accomplished by an interdental brush of the type mentioned in the introduction, in which the brush head is embodied as a single-component injection-molded part. 
         [0008]    It is advantageous here that the entire brush head and thus both the bristles and the bristle carrier can be manufactured from a plastic material in a single manufacturing step. In particular, manufacturing the bristle carrier from an injection-moldable plastic material facilitates the manufacture of an elastic and/or flexible bristle carrier and/or brush head. The risk of injury to the gums and/or dental enamel can be reduced hereby. In addition, an interdental brush according to the present invention can be embodied in an especially short time and/or in an especially cost-effective manner. In particular, the brush head is configured as a rotationally symmetrical brush head in relation to the longitudinal axis or central axis of the bristle carrier. The brush head can thus have an essentially round cross section. Due to a metal core being eliminated, the interdental brush according to the present invention, especially the brush head, can be disinfected and/or optionally even autoclaved more hygienically and/or better, especially because a suitable material is selected. The risk of spreading microorganisms can be markedly reduced hereby in case of multiple use. In addition, the risk of an undesired interaction, especially oxidation, of the interdental brush or of the brush head during storage and/or cleaning in a solution, especially in a chlorhexidine solution, is considerably reduced and preferably completely eliminated. 
         [0009]    The brush head with the bristle carrier and with the bristles preferably consists of a single plastic material suitable for injection molding. The brush head can thus be manufactured in a cost-effective manner in a single manufacturing step. The brush head, bristle carrier and/or bristles are preferably elastic and/or flexible. The risk of injury to the gums and/or dental enamel and/or of damage to dental implants is considerably reduced as a result. In addition, the cleaning area in an interdental space, especially in a region of the neck of a tooth, can be optimized and/or enlarged hereby. The rigidity of the bristles is preferably lower than the rigidity of the bristle carrier. This is achieved, in particular, by the thickness of the material of the bristle carrier being selected to be greater than the thickness of the material of the bristles. The bristle carrier may also be called core, especially of the brush head. 
         [0010]    The brush head may be pushed, especially optionally, into the interdental space, preferably at least partially through the interdental space, from the lingual direction or from the buccal direction. Due to the elastic and/or flexible properties of the brush head, of the bristle carrier and/or of the bristles, the brush head is compressed in a narrowed middle area of the interdental space. The brush head unfolds again on exiting the narrowed area on the push-out side facing away from the push-in side of the interdental space. As a result, the entire interdental space can be cleaned, especially on both the lingual side and the buccal side. The interdental brush is preferably moved to and fro in the interdental space for cleaning the interdental space. 
         [0011]    According to another embodiment, directly adjacent bristles are arranged with an angle difference of less than 90° on the bristle carrier. In particular, the angle difference pertains to directly adjacent bristles, which are arranged in a plane extending crosswise and/or at right angles to the longitudinal axis of the bristle carrier. The bristles may be arranged in a plurality of planes, which are arranged transversely and/or at right angles to the longitudinal axis of the bristle carrier and are located at spaced locations from one another in the longitudinal direction of the bristle carrier. In particular, at least 15 or at least 18 planes are provided. Twenty-five to 100 planes, especially 18 or 50 planes, are preferably provided. The bristles of two planes directly following each other in the longitudinal direction of the bristle carrier may be arranged offset in relation to one another by half the angle difference between two directly adjacent bristles in the same plane. The angle difference of two directly adjacent bristles preferably equals less than 60°, preferably less than 45° and preferably less than 30°. The angle difference of directly adjacent bristles, especially in a plane extending crosswise and/or at right angles to the longitudinal axis of the bristle carrier, especially preferably equals a value between 30° and 40°. The angle difference is especially exactly 36° or 72°. A high density of bristles extending away from the bristle carrier in an radially outward manner can thus be achieved. The cleaning action is considerably improved hereby. 
         [0012]    According to one variant, the bristles have a bristle length in the range of 1 mm to 2.5 mm. In particular, the bristle length equals 1 mm, 1.5 mm, 1.95 mm or 2 mm. The bristle length is preferably measured or determined from an imaginary center line or central axis of the bristle carrier. The bristles may have an essentially cylindrical configuration. The bristles preferably taper away from the bristle carrier in the direction of a bristle tip. In particular, the bristles have a conical configuration. The tip of the bristle may have a rounded configuration especially to reduce the risk of injury. 
         [0013]    The bristles may have a circular, semicircular or essentially semicircular, especially crescent-shaped cross section. In particular, the bristles have each a wall section with a bent and/or essentially semicircular cross section and a flat, preferably planar wall section. The bristles can thus be configured as full bristles or as half bristles cut in the longitudinal direction. If a uniformly configured base is used, the use of half bristles can make it possible to arrange a greater number of bristles than when full bristles are used. The bristles having an essentially semicircular or crescent-shaped cross section may taper away from the bristle carrier in the direction of the bristle tip. The flat and/or planar wall sections of the bristles may be aligned parallel to one another and/or parallel to the longitudinal direction of the bristle carrier. In particular, the flat and/or planar wall sections of the bristles, which are arranged in a plane extending transversely and/or at right angles to the longitudinal axis of the bristle carrier, may be aligned parallel to one another. The flat and/or planar wall sections, especially those that are arranged in the same plane, are preferably aligned in the same direction. 
         [0014]    The bristles preferably have a maximum diameter in the range of 0.1 mm to 0.25 mm. The maximum diameter of the bristles preferably equals 0.1 mm or 0.2 mm. The maximum diameter of the bristles may be associated with a bristle base connected to the bristle carrier. The bristle base is an integral part of the bristle here. In particular, the bristle base is located at an end of the bristle facing away from the bristle tip. The maximum diameter of the bristle is arranged, especially in case of a conically configured bristle, in the area of the bristle base connected to the bristle carrier. 
         [0015]    According to one variant, the bristle carrier and/or a bristle area of the bristle carrier, which area is provided with bristles, has a length in the range of 5 mm to 35 mm. The bristle carrier and/or a bristle area of the bristle carrier that is provided with bristles preferably has a length in the range of 10 mm to 25 mm. In particular, the bristle carrier and/or the bristle area has a length in the range of 12 mm to 20 mm. The length of the bristle carrier and/or of the bristle area preferably equals 15 mm, 16.4 mm or 20 mm. 
         [0016]    The bristle carrier may have a diameter in the range of 0.5 mm to 1.5 mm. The diameter of the bristle carrier is preferably in the range of 0.7 mm to 0.9 mm. The bristle carrier and/or the brush head can thus be inserted into usual interdental spaces without problems. The elongated bristle carrier may have an essentially cylindrical and/or rod-shaped configuration. The bristle carrier preferably has a conical configuration, the bristle carrier tapering, especially away from the grip part, in the direction of a tip of the bristle carrier. In particular, a tip of the bristle carrier, which tip faces away from the grip part, is rounded. Insertion into the interdental space is facilitated and/or the risk of injury is further reduced hereby. The tip of the bristle carrier may likewise be provided with bristles. For example, the tip of the bristle carrier may have a spherical segment-like configuration. Bristles preferably extend away from the surface of the spherical segment-like tip of the bristle carrier in a radially outward manner. In particular, the tip of the bristle carrier has a hemispherical configuration. 
         [0017]    In particular, the bristle carrier has a maximum diameter in the range of 0.5 mm to 2 mm and preferably in the range of 0.6 mm to 1.4 mm. The bristle carrier especially preferably has a maximum diameter of 0.6 mm or 1.4 mm. The area of the bristle carrier with the maximum diameter may be arranged at the grip part. The bristle carrier may preferably have a minimum diameter in the range of 0.2 mm to 1 mm and preferably in the range of 0.4 mm to 0.9 mm. The bristle carrier especially preferably has a minimum diameter of 0.4 mm or 0.9 mm. The minimum diameter of the bristle carrier may be associated with an end of the bristle carrier facing away from the grip and/or with a tip of the bristle carrier. 
         [0018]    The number of bristles on the bristle carrier and/or in the bristle area of the bristle carrier is preferably in the range 50 to 1,000 bristles. The number of bristles is preferably in the range of 300 to 840 bristles. At least 90, 150 or 180 bristles are preferably provided. Ninety, 180 or 500 bristles are preferably provided on the bristle carrier and/or in the bristle area of the bristle carrier. A large number of very thin and high-quality bristles are thus provided, as a result of which the cleaning action of the interdental brush is improved. 
         [0019]    According to one variant, the brush head has a flow path to wall thickness ratio greater than 20. In particular, the flow path to wall thickness ratio is greater than 30 for the brush head. The flow path to wall thickness ratio is preferably in a range of 30 to 50. The flow path to wall thickness ratio is especially in the range of 20 to 30 or in the range of 35 to 45. The flow path to wall thickness ratio preferably has a value of 38. The interdental brush with the grip part may have a flow path to wall thickness ratio in the range of 20 to 50 and/or in the range of 40 to 60. The brush head, especially the interdental brush without grip part, may have a flow path to wall thickness ratio in the range of 20 to 30, especially exactly 25.2, or in the range of 40 to 50, especially exactly 42.8. The flow path to wall thickness ratio sets the flow path that the component or the plastic has to cover during the injection molding in relation to the wall thickness of the injection-molded part to be manufactured. The greater the flow path to wall thickness ratio, the lower must be the viscosity of the material or plastic used. The injection-molded part is preferably molded with increased pressure at high flow path to wall thickness ratios greater than 20 and/or greater than 30. The flow path to wall thickness ratio is preferably obtained from the length of the brush head divided by the diameter of the bristle carrier plus the length of a bristle divided by the diameter of the bristle in case of the brush head. 
         [0020]    The interdental brush preferably has a grip part. In particular, the grip part is connected to the brush head. The grip part may be configured as an especially axial extension of the bristle carrier. The brush head connected to the grip part is preferably configured as a single-component injection-molded part or as a two-component injection-molded part. Especially favorable manufacturing costs and/or short manufacturing times can be obtained in case of a single-component configuration of the interdental brush with the brush head and with the grip part. It is also conceivable, as an alternative, that the grip part is molded onto an end of the bristle carrier facing away from a tip of the bristle carrier. In case of a two-component injection-molded part comprising the brush head and the grip part, the grip part is manufactured from a plastic material different from that of the brush head. As a result, the grip part can be manufactured, for example, from a rigid or stiff plastic material, whereby the grip part is improved. By contrast, the brush head is manufactured from an elastic and/or flexible plastic material, whereby the cleaning action is improved and the risk of injury or damage is reduced. The brush head and the grip part may be arranged at a predefined angle in relation to one another. The longitudinal axis of the brush head is preferably arranged at an angle in a range of 0° to 90° in relation to the longitudinal axis of the grip part. The angle between the longitudinal axis of the brush head and the longitudinal axis of the grip part is especially about 30°, about 45°, about 60° or about 90°. The diameter of the grip part is preferably smaller than the maximum diameter of the brush head. The diameter of the grip part is especially in the range of 3.0 mm to 4.0 mm, and the diameter of the grip part is preferably 3.45 mm. The length of the grip part may be in the range of 10 mm to 30 mm. The length of the grip part is especially 11 mm. 
         [0021]    According to another embodiment, a plastically deformable aligning segment is arranged between the brush head and the grip part for manually aligning the brush head in relation to the grip part. As a result, the brush head can be aligned, bent and/or kinked in relation to the grip part in a plurality of different positions. The use of the interdental brush in a limited space, for example, within a mouth, is facilitated hereby. A longitudinal axis of the brush head and/or of the bristle carrier can preferably be aligned and/or bent by at least up to 45°, especially by up to at least 90° from the longitudinal axis of the grip part by means of the aligning segment. The longitudinal axis of the brush head and/or of the bristle carrier can thus be bent and/or kinked hereby in relation to the longitudinal axis of the grip part. The aligning segment especially provides a kink point. 
         [0022]    An especially manual cleaning of interdental spaces and/or dental implants is facilitated by means of the interdental brush according to the present invention. At the same time, the risk of injury to the gums and/or dental enamel as well as damage to a dental implant is considerably reduced. 
         [0023]    The present invention will be explained in more detail below on the basis of the figures. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    In the drawings: 
           [0025]      FIG. 1  is a perspective side view of an interdental brush according to the present invention; 
           [0026]      FIG. 2  is a perspective side view of a brush head for the interdental brush according to the present invention according to  FIG. 1 ; 
           [0027]      FIG. 3  is a side view of the interdental brush according to the present invention according to  FIG. 1  and  FIG. 2 ; 
           [0028]      FIG. 4  is a side view of the brush head according to  FIGS. 2 and 3 ; and 
           [0029]      FIG. 5  is a perspective side view of a second brush head for an interdental brush according to the present invention; 
           [0030]      FIG. 6  is a perspective side view of another brush head for an interdental brush according to the present invention, and 
           [0031]      FIG. 7  is a front view of an individual bristle. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]    Referring to the drawings,  FIG. 1  shows a perspective side view of an interdental brush  10  according to the present invention. The interdental brush  10  has a brush head  11  and a grip part  12 . The brush head  11  has an elongated bristle carrier  13 , which has an essentially rod-shaped configuration. The bristle carrier  13  has an exposed tip  14  in this exemplary embodiment. Furthermore, the tip  14  has a hemispherical configuration in this exemplary embodiment. In an alternative embodiment, bristles, not shown more specifically here, may extend from the outer circumference of the hemispherical tip  14  in a radially outward manner and away from the hemispherical surface of the tip  14 . The hemispherical tip  14  has a maximum diameter and the bristle carrier  13  has a minimum diameter of 0.9 mm in this exemplary embodiment. An end of the bristle carrier  13  facing away from the tip  14  passes over into the essentially cylindrical grip part  12 . An aligning segment  15  is arranged between the brush head  11  and the grip part  12  in this exemplary embodiment. 
         [0033]    A plurality of bristles  16  extend from the outer circumference of the elongated bristle carrier  13  in a radially outward manner in relation to the longitudinal axis of the bristle carrier  13 . Not all bristles  16  are provided with a reference number for the sake of greater clarity. A bristle area of the bristle carrier  13 , which area is provided with bristles  16 , has a length of 15 mm in this exemplary embodiment. The brush head  11 , comprising the bristle carrier  13  and the bristles  16 , is formed from a single-component plastic material and is made as a single-component injection-molded part. The bristle carrier  13  and the bristles  16  are elastic and flexible. The grip part  12  has a length that is shorter than the length of the brush head  11  and of the bristle carrier  13  in this exemplary embodiment. 
         [0034]      FIG. 2  shows a perspective side view of the brush head  11  for the interdental brush  10  according to the present invention according to  FIG. 1 . The bristles  16  have an outwardly conically tapering shape. The bristles  16  have a bristle length of about 1 mm in this exemplary embodiment. Furthermore, the bristles  16  have a conical shape. The bristles  16  have each a bristle tip  17 , which has a hemispherical configuration in this exemplary embodiment. The bristles  16  have a bristle base  18  each at the end facing away from the exposed bristle tip  17 . The bristle base  18  is connected in one piece to the bristle carrier  13 . The bristles  16  have their maximum diameter each, which equals 0.2 mm in this exemplary embodiment, in the area of the bristle base  18 . Not all bristle tips  17  and bristle bases  18  are provided with a reference number for the sake of greater clarity. 
         [0035]      FIG. 3  shows a side view of the interdental brush  10  according to the present invention according to  FIGS. 1 and 2 . The aligning segment  15 , which can clearly be seen here, provides a kinking point for bending the brush head  11  by up to 90° in relation to the longitudinal axis of the grip part  12  when needed. Starting from the aligning segment  15  or the grip part  12 , the elongated bristle carrier  13  tapers in the direction of the tip  14 . The bristle carrier  13  has a slightly conical configuration in this exemplary embodiment. 
         [0036]      FIG. 4  shows a side view of the brush head  11  according to the above figures. The bristles  16  are arranged in a plurality of planes along the longitudinal axis of the elongated bristle carrier  13 . The planes of the bristles  16  are aligned here each at right angles to the longitudinal axis of the bristle carrier  13  and parallel to one another. A total of 50 planes of bristles  16  are arranged following each other in the longitudinal direction of the bristle carrier  13 . 
         [0037]    Furthermore, ten bristles  16  are located at uniformly spaced locations from one another in a plane extending at right angles to the longitudinal axis of the bristle carrier  13  in this exemplary embodiment. The angle difference between two directly adjacent bristles  16  in the same plane at right angles to the longitudinal axis of the bristle carrier  13  equals 36° in this exemplary embodiment. Thus, a total of 500 bristles are arranged on the bristle carrier  13  in this exemplary embodiment. 
         [0038]    Moreover, it can be seen that two planes each that directly follow one another in the direction of the longitudinal axis of the bristle carrier  13  and are aligned at right angles to the longitudinal axis of the bristle carrier  13  are provided with bristles  16  offset by half the angle difference between two directly adjacent bristles  16  in the same plane. 
         [0039]      FIG. 5  shows a perspective side view of a second brush head  19  for an interdental brush according to the present invention. The second brush head  19  may be provided instead of the brush head  11  according to  FIGS. 1 through 4 . 
         [0040]    Just like the brush head  11  according to  FIGS. 1 through 4 , the second brush head  19  also has an elongated bristle carrier  20 , which has an essentially rod-shaped configuration and an exposed tip  21 . Furthermore, the tip  21  has a hemispherical configuration in this exemplary embodiment. In an alternative embodiment, bristles, not shown more specifically here, may extend from the outer circumference of the hemispherical tip  21  in a radially outward manner and away from the hemispherical surface of the tip  21 . The hemispherical tip  21  has a maximum diameter and the bristle carrier  20  has a minimum diameter of 0.4 mm in this exemplary embodiment. An end of the bristle carrier  20  facing away from the tip  21  is connected to the grip part  12 , which is not shown more specifically here. The bristle carrier  20  has a maximum diameter of 0.6 mm at its end facing the grip part  12 . The bristle carrier  20  thus has a shape tapering conically towards the tip  21 . 
         [0041]    A plurality of bristles  16  extend radially from the outer circumference of the elongated bristle carrier  20  in a radially outward manner in relation to the longitudinal axis of the bristle carrier  20 . Not all bristles  16  are provided with a reference number for the sake of greater clarity. The bristle carrier  20  has a length of 16.4 mm in this exemplary embodiment, and a section in the area of the tip  21  remains free from bristles in this example. The brush head  19 , comprising the bristle carrier  20  and the bristles  16 , is formed from a single plastic material and is formed as a single-component injection-molded part. 
         [0042]    In this exemplary embodiment, the bristles  16  have a maximum bristle length of about 2 mm in the area of the end facing the grip part  12  and a minimum bristle length of 1 mm in the area of the end facing the tip  21 . The bristle length decreases continuously in the direction of the tip, so that an essentially conical envelope is obtained around the bristle tips  17 . 
         [0043]    The bristles  16  are arranged in a total of 18 planes following each other in the longitudinal direction of the bristle carrier  20  in this exemplary embodiment. Furthermore, five bristles  16  each are located at uniformly spaced locations from one another in a plane extending at right angles to the longitudinal axis of the bristle carrier  20  in this exemplary embodiment. The angle difference between two directly adjacent bristles  16  in the same plane at right angles to the longitudinal axis of the bristle carrier  20  equals 72° in this exemplary embodiment. Thus, a total of 90 bristles are arranged on the bristle carrier  20  in this exemplary embodiment. 
         [0044]    Moreover, it can be seen that two planes each, which directly follow one another in the direction of the longitudinal axis of the bristle carrier  20  and are aligned at right angles to the longitudinal axis of the bristle carrier  20 , are provided with bristles  16  offset by half the angle difference, for example, by 36° here, in relation to the alignment of bristles  16  in an adjacent plane. 
         [0045]      FIG. 6  shows a perspective side view of another brush head  22  for an interdental brush according to the present invention. The other brush head  22  may be provided instead of the brush head  11  according to  FIGS. 1 through 4 . Reference is made, as above, to the preceding description concerning identical features. 
         [0046]    The other brush head  22  extensively corresponds to the second brush head  19  according to  FIG. 5 , but the other brush head  22  has twice as many, namely, 180, bristles  16 . Two directly adjacent planes of bristles  16  form each a plane pair, in which the bristles  16  of the two individual planes are arranged uniformly on the bristle carrier  20 . Thus, a total of 18 plane pairs of bristles  16  and a total of 36 individual planes of bristles  16  are present. 
         [0047]    Two plane pairs  16  with bristles each, which pairs follow each other directly in the direction of the longitudinal axis of the bristle carrier  20  and are aligned at right angles to the longitudinal axis of the bristle carrier  20 , are offset by half the angle difference, for example, by 36° here, in relation to the alignment of the bristles  16  in relation to the bristle carrier  20  of an adjacent plane pair. 
         [0048]      FIG. 7  shows a front view of an individual bristle  23 . Contrary to a bristle  16  according to  FIGS. 1 through 6 , which can be considered to be a full bristle, the bristle  23  is configured as half a bristle  16 . 
         [0049]    The bristle  23  has an essentially semicircular or crescent-shaped cross section. The bristle  23  has a first wall section  24  with an essentially semicircular cross section and a flat, preferably planar, second wall section  25 . Thus, the bristle  23  is a bristle  16  cut in the longitudinal direction. The bristle  23  may be used instead of the bristle  16  or alternatingly with the bristle  16 . Starting from a bristle base  26 , the bristle  23  tapers in the direction of a bristle tip  27 . 
         [0050]    While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.