Abstract:
The present invention relates to a finger toothbrush  10  wherein the bristles  16  adjacent the tip  18  of the toothbrush  10  are the shortest in height to enhance the ability of the toothbrush to fit into the narrow space between the cheek and the facial surfaces of the rear molars to provide for the maneuverability necessary to achieve the desired cleaning of the rear molars.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to toothbrushes and more particularly, to toothbrushes mounted on a finger and having shorter bristles adjacent the tip thereof to enhance access to and cleaning of the back teeth.  
         BACKGROUND OF THE INVENTION  
         [0002]    Finger mounted toothbrushes are well known in the art as a low cost means of providing a toothbrush with enhanced control in brushing. Examples of such prior art toothbrushes are disclosed in U.S. Pat. Nos. 2,077,540, 2,915,767, 2,921,590, 3,583,019, 3,798,698, 4,134,172, 4,679,274 and 5,287,584, among others, all of which provide bristles or other tooth cleaning elements which generally have a generally flat bristle trim or a uniform bristle height, i.e. the length which the bristles extend from the surface of the finger toothbrush to which they are secured. To provide adequate access to the facial tooth surfaces of the rear molars, these prior art toothbrushes must fit between the narrowing distance between the facial surfaces of the teeth and the cheek near the rear of the mouth. Unfortunately, while the finger does thin towards its end, this thinning does not allow sufficient entry of the tip of these finger mounted prior art toothbrush with their generally uniform flat trim bristle height into the narrowed space between the facial side of the rear molars and the cheek to provide sufficient room for maneuvering and adequate cleaning.  
           [0003]    U.S. Pat. No. 4,617,694 discloses a toothbrush with a specially contoured bristle pattern disclosed as providing enhanced cleaning to all teeth, particularly to those at the rear of the mouth. The height or length of the bristles disclosed in this toothbrush increases uniformly toward the tip of the brush, i.e. the tip of the finger. This increasing bristle length toward the tip of the toothbrush, when the combined decreasing thickness of the finger toward the tip of the toothbrush (See, FIG. 1 in U.S. Pat. No. 4,617,694) keeps the total combined thickness of finger and bristles at a generally constant thickness. Such a constant thickness does not allow sufficient access of the tip of this finger mounted toothbrush into the narrowing space between the cheek and the facial surfaces of the rear molars, the same problem as disclosed herein above with respect to other prior art finger toothbrushes.  
           [0004]    Thus there is a clear need for a low cost finger toothbrush with a configuration that allows it to fit into the narrowing space between the cheek and the facial surfaces of the back molars to provide the desired cleaning thereof.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    The present invention encompasses a finger toothbrush wherein the bristles most adjacent the tip of the brush are the shortest in height as measured from the brush face and the bristles furthest from the tip of the brush are the longest as measured from the brush face. Providing such short bristles at the tip of the finger toothbrush reduces the overall height of the tip to allow it to adequately fit into the narrow space between the cheek and the facial surfaces of the rear molars to reach and clean the rear molars and surrounding gum tissues. Further, the longer bristles, located away from the tip of the subject finger toothbrush will provide a more pleasant softer feel to the user and an enhanced ability to penetrate into the interproximal spaces between the teeth for enhanced cleaning therein.  
           [0006]    Alternate embodiments of the present finger toothbrush invention include bristles which linearly ramp down in height as measured from the brush face to the shortest bristles adjacent the tip, or which arcuately ramp down in height, in for example a concave arc, measured from the brush face to the shortest bristles adjacent the tip (a concave arc which better conforms to the curvature of the teeth). The bristles, in the present finger toothbrush, may be grouped in conventional bristle tufts and aligned in rows, wherein the closest row or rows of tufts to the tip of the toothbrush are the shortest. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The above disclosed and other features, objects and advantages of the present invention will be better understood from a reading of the detailed description of the preferred embodiment in conjunction with the following drawings, in which:  
         [0008]    [0008]FIG. 1 is a side view of a preferred embodiment of the finger toothbrush of the present invention;  
         [0009]    [0009]FIG. 1A is a side view of an alternative embodiment of the finger toothbrush of the present invention;  
         [0010]    [0010]FIG. 2 is a perspective view, showing the finger toothbrush of FIG. 1, wherein the bristles are mounted on a rigid plastic face enclosed in an elastomeric frame.  
         [0011]    [0011]FIG. 3 is a top view, showing the finger toothbrush of FIG. 1.  
         [0012]    [0012]FIG. 4 is a perspective view showing in isolation the elastomeric frame of FIG. 2. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    Referring to the drawings, wherein like reference numerals refer to the same or similar elements among the several figures, there is shown a finger toothbrush  10  in accordance with the present invention, i.e. the bristles or bristle tufts  16  closest to the tip  18  of the finger toothbrush  10  are the shortest bristles  16  and the bristles furthest from the tip  18  are the longest. In a first embodiment of the present invention shown in FIG. 1, the finger toothbrush  10  has a generally tubular finger grip section  20  extending along a portion of the length of the back-side  32  of a rigid platform  14 . The bristles  16  may be organized in a plurality of bristle tufts (also designed as  16 ) aligned in rows and securely mounted and extend from the front side or brush face  22 . The length or height of the rows of bristles or bristle tufts  16  from the face  22 , uniformly decrease along the longitudinal axis of the finger toothbrush  10  toward the tip  18  thereof, easing entry of the finger toothbrush  10  into the narrowing space between the cheek and the facial surface of the molars in the rear of the mouth for enhanced cleaning thereof.  
         [0014]    In a second embodiment of the present invention, as illustrated in FIG. 1A, the bristle tufts  16  decrease in height linearly in a 1st region furthest from the tip  18  of the finger toothbrush  10  and continue to decease in height in a 2nd region until the shortest tufts of a uniform height is reached for the bristle tufts  16  nearest the tip  18 . In another alternate embodiment, the bristle tufts  16  may be uniform as well as decreasing in height in the 1st region furthest from the tip  18  of the finger toothbrush  10  and then continue to decease in height in a 2nd region until the shortest tufts of a uniform height is reached for the bristle tufts  16  nearest the tip  18 . Finally, in a third alternate embodiment, the bristles may decrease in height in an arcuately along the length or part of the length of the brush face  22 , in for example a concave curve which is concave towards the brush face  22 , such that the shortest bristle tufts  16  are adjacent to the brush tip  18  and the tallest bristle tufts  16  are furthest from the brush tip  18 .  
         [0015]    Referring again to FIG. 1, the row of bristles furthest from the tip  18  of the finger toothbrush  10  of the present invention extend from the face  22  a height of about 8 to about 14 mm, preferably about 8 to about 11 mm and most preferably about 9 mm. The bristles nearest the tip  18  of the finger toothbrush  10  extend from the face  22  a height of about 4 to about 7 mm, preferably about 5 to 7 mm, and most preferably about 6 mm.  
         [0016]    The generally tubular finger grip section  20  may be integrally mounted to the edges  30  of the rigid platform  14  or to the back-side  32  of the rigid platform  14  itself, preferably being mounted along the edges  30  right at the juncture of the edges  30  and the rigid platform  14  (see FIG. 4). The diameter of the tube aperture through the tubular finger grip section  20  may be from about 1.5 to about 2.5 mm, preferably about 2.0 mm. The tubular finger grip section  20  may contain a slit  36 , aligned in the general direction of the longitudinal axis of the finger toothbrush and extending 40%, 50% or more of the length of the tubular finger grip section  20  toward the tip of the toothbrush  18 . This slit  36  provides added flexibility to the tubular finger grip section  20  to accommodate larger fingers.  
         [0017]    The cross-section of the monofilament bristles  16 , useful in the present invention may be circular, oval, rectangular or polygonal, with a diameter or is largest cross-sectional dimension of from about 0.10 mm to about 0.40 mm or more. The monofilament bristles  16  may be made of the same or different polymeric materials, including aliphatic polyamides, aromatic polymides, polyesters, polyolefins, styrenes, fluoropolymers, polyvinylchloride (PVC), polyurethane, polyvinylidene chloride, and polystyrene and styrene copolymers, or combinations thereof. A preferred material is 6,12 nylon; though other nylons may be used, including 4 nylon, 6 nylon, 11 nylon, 12 nylon, 6,6 nylon, 6,10 nylon, 6,14 nylon, 10,10 nylon, 12,12 nylon and other nylon co-polymers. A particularly preferred 6,12 nylon is sold under the tradename TYNEX®, and is manufactured by E.I. DuPont de Nemours and Company of Wilmington, Del.  
         [0018]    The finger toothbrush  10  of the present invention may be formed of an external rubber or elastomeric frame  24  shown in FIG. 4 into which a more rigid plastic is overmolded, to form the completed finger toothbrush as illustrated in FIGS.  1  to  3 . The elastomeric frame  24  provides cushioning and an avoidance of abrasion to the soft tissues of the cheek and gums and the rigid overmolded plastic provides a rigid structure to the finger toothbrush  10  and a means to securely fasten the bristles  16  therein. To provide such cushioning and abrasion avoidance, the elastomeric frame  24  may be manufactured of natural rubber or a thermoplastic elastomer (TPE), or a combination thereof. Such acceptable materials include thermoplastic vulcanate (TPV) which consists of a mixture of polyproplyene and EPDM (ethylene propylene diene monomers) which is available as Santoprene (brand), described in U.S. Pat. No. 5,393,796; or Vyram (brand), another TPV consisting of a mixture of polypropylene and natural rubber; both Santoprene and Vyram being elastomers marketed by Advanced Elastomer Systems LP, Akron, Ohio 44311. Another, and preferred TPE is Dynaflex G6713 (brand), marketed by GLS Corp., Cary, Ill. 60013. These and other suitable elastomers typically have a Shore A hardness of from about 13 to 94, with about 29 being a preferred hardness. The elastomeric frame  24  should be at least 0.5 mm in thickness, preferably at least 1.59 mm in thickness, though the thickness need not be uniform about the entire body of the elastomeric frame  24 .  
         [0019]    The overmolded rigid plastic, about the elastomeric frame shown in FIG. 4, includes a rigid platform  14  having a plurality of bristle holes in the face  22  thereof, into which holes the rows of bristles  16  are fastened, preferably using conventional staple technology. The overmolded rigid plastic is preferably manufactured of a thermoplastic, especially polypropylene, though other rigid plastic materials, such as polyester may be used. A suitable polypropylene, with a flexural modulus of 216,000 psi (15,186 kilograms/cm 2 ) by ASTM test method D790, is available from Huntsman Corporation, Longview, Tex., 75603 under the trade-designation Huntsman Polypropylene P4G3Z-039. Another suitable polypropylene is available from Amoco Polymers, Inc., Alpharetta, Ga. 30202-3914, sold under the trade designation 7635 with a flexural modulus of about 275,000 psi (19,334 kilograms/cm 2 ). Use of a toothbrush handle of such a 216,000 psi (15,186 kilograms/cm 2 ) to 275,000 psi (19,334 kilograms/cm 2 ) material will provide enhanced rigidity to allow the rows of bristles  16  to be securely fastened therein.  
         [0020]    The manufacture of toothbrushes of the present invention can be facilitated by using known, conventional two-step injection molding processes. Within such a two-step injection molding process, the elastomeric frame  24  is initially injection molded. The elastomeric frames are then positioned within a second mold and the rigid plastic is injection molded about the elastomeric frame  24 , to form the completed finger toothbrush body. Finally the bristles  16  are secured to the rigid plastic platform by known manufacturing techniques, including the use of conventional staple technology.  
         [0021]    Conventional two component injection molds useful in the manufacture of the present invention are available from Machines Boucherie NV, Izegem, Belgium. Which molds can be mounted in typical injection molding machines, such as 300 ton injection molding machines available from Engel Canada, Inc., Guelph, Ontario.