Abstract:
According to the practice of the present invention, a toothbrush with two distinct, flexible bristle groups, a more densely packed first bristle group adjacent the toe of the toothbrush and a less densely packed second bristle group further from the brush toe, each group containing at least one radius of curvature and the second grouping containing two subsets of bristle tufts, the first subset of bristle tufts angled toward the toe of the toothbrush and the other away therefrom, which combination of features provides enhanced conformity to the curvature of the teeth and enhanced cleaning thereof.

Description:
FIELD OF THE INVENTION 
     The present invention relates to toothbrushes, and more particularly, to toothbrushes having a particular combination of bristle tuft flexibility, density, angles and trim to provide enhanced conformity to the topography of the teeth for better cleaning thereof. 
     BACKGROUND OF THE INVENTION 
     The primary purpose of toothbrushes is to clean the teeth by removing plaque and debris from the tooth surfaces, including the curved outer tooth surfaces and the interproximal surfaces between the teeth, i.e. the topography of the teeth. To facilitate such cleaning, conventional toothbrushes comprise generally uniform length tufts of bristles, a flat bristle trim, each bristle having an end which is held captive in and fixed to a brush head, and an end which is free and which is used for brushing. Toothbrushes having such a generally flat bristle trim are limited in their ability to conform to the curved surfaces of each tooth or to penetrate into the interproximal areas between the teeth. 
     The desire of users to cause brushes having such generally flat bristle trims to conform to the curved teeth and to penetrate into and reach the interproximal tooth surfaces is expressed by the forceful application of the brush to adequately deform the bristles to the topography of the teeth. Such forceful application of the brush deleteriously leads to excessive wear and irritation of gums without adequate conformation of the brush about and between the teeth to provide the desired cleaning. 
     U.S. Pat. No. 5,742,972 discloses a toothbrush having a bristle trim containing at the toe region of the head, furthest from the handle, a ramping down subset of bristle tufts with the longest bristle tuft adjacent to the toe. Along the heel region of the head, closest to the handle, is a series of bristle rows wherein any transverse cross-section of which is concave in shape, i.e. the bristle tufts along each side of the brush being longer than those closer to the center of the brush. This combination of tufts is designed to provide enhanced interproximal and gingival margin cleaning by better conforming to the curved surfaces of and between the teeth. While this combination of tufts does provide better conformity to the topography of the dentiture than a conventional uniform length, flat trim toothbrush; it does not have the diversity of tufts and trim necessary to provide the enhanced cleaning desired. 
     Alternately, U.S. Pat. Nos. 5,335,389, 5,341,537, 5,446,940 and U.S. Pat. No. Des. 352,396 disclose various other toothbrushes containing a combination of longer and shorter bristle tufts and bristle bars, which are orthogonal and acutely angled to the face of the disclosed toothbrushes. As in the case of U.S. Pat. No. 5,742,972, these toothbrushes will better conform to the curved surfaces of the teeth than conventional flat trim toothbrushes; but, also as in the case of U.S. Pat. No. 5,742,972, they do not have the diversity of bristle tufts and trim to provide the enhanced cleaning desired. 
     PCT International Publication WO 99/23910 discloses a toothbrush with a greater diversity of tufts, i.e. five (5) different bristle tufts, including a first enlarged tuft located at the toe of the toothbrush with a cross-sectional area of about 0.0373 square inches (0.241 cm 2 ). This enlarged tuft is composed of uniform, flat trimmed, 0.440 inch (11.176 mm) long bristles which are densely packed and this enlarged tuft is angled forward to extend over the toe of the toothbrush. The other disclosed bristle tufts are arranged substantially in three columns along the balance of the brush head, each column containing about 10 rows of alternating length tufts. The two peripheral columns, along each side of the head, contain 0.350 inch (8.890 mm) long, round cross-section tufts, which are 0.0027 sq. inches (0.0174 cm 2 ) in cross-sectional area; alternating with 0.440 inch (11.176 mm) long rectangular tufts, 0.0045 sq. inches (0.029 cm 2 ) in cross-sectional area. The center column contains 0.440 inch (11.176 mm) long, 0.0045 sq. inch (0.029 cm 2 ) rectangular tufts alternating with shorter, 0.350 inch (8.890 mm) long, 0.0084 sq. inch (0.0542 cm 2 ) rectangular tufts. As disclosed in U.S. Pat. No. 5,511,275, a bristle tuft&#39;s stiffness is directly proportional to the number of bristles in that tuft and to the density of the packing, i.e. a buttressing factor. The large, 0.0373 (0.241 cm 2 ) and 0.0084 square inch (0.0542 cm 2 ), densely packed, uniform flat trimmed bristle tufts disclosed in WO 99/23910 will exhibit significant buttressing and stiffness as described in U.S. Pat. No. 5,511,275, reducing the brushes ability to conform to the curved surfaces of the teeth without deleterious, excessive forceful application of the toothbrush by the user. 
     There is a need in the art for a toothbrush having a diversity of tufts, including curved bristle trim and wherein the bristle tufts better conform to the curvature of the teeth to provide enhanced cleaning without the need for deleterious, excessive brushing force by the user. 
     SUMMARY OF INVENTION 
     The present invention comprises a toothbrush with an elongated head connected to an elongated handle, which head has a first and a second grouping of flexible bristle tufts extending therefrom, both groupings have trim patterns containing at least one radius of curvature to provide enhanced conformity to the curvature of the teeth; the first grouping, located nearer the toe of the brush head, contains bristle tufts angled slightly towards the toe of the toothbrush, and wherein the bristle tufts are relatively more densely packed, providing a combination of features which provides the flexibility and configuration of bristle tufts to conform to the curvature of the tooth to provide enhanced cleaning thereof. The second grouping contains a first subset of bristle tufts about the periphery of the second grouping acutely angled toward the toe of the toothbrush and a second subset bristle tufts acutely angled toward the handle of the toothbrush, which two subsets of bristle tufts are relatively less densely packed, for a combination of features which provides enhanced penetration of the interproximal spaces between the teeth during back and forth brushing of the facial and lingual tooth surfaces, a brushing method used by a significant percentage of users. 
     A second embodiment of the present invention comprises the two groupings of bristle tufts of the first embodiment, wherein in the second grouping the rows of bristle tufts are alternatingly longer and shorter, allowing each longer row to more deeply penetrate the interproximal spaces to reach and clean the tooth surfaces therein, without the interference of the adjacent rows abutting against the facial or lingual surfaces of the teeth, thereby enhancing the ability of the toothbrush to better conform to the curvature of the teeth for enhanced cleaning thereof. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     While the specification concludes with the claims which particularly point out and distinctly claim the invention, it is believed the present invention will be better understood from the following description of several particularly preferred embodiments taken in conjunction with the accompanying drawings, in which like reference numerals identify similar elements and wherein: 
     FIG. 1 is a perspective view, showing an embodiment of the toothbrush bristle pattern of the present invention; 
     FIG. 2 is a side elevation of the embodiment of FIG. 1, the other side elevation being a mirror image of FIG. 2; 
     FIG. 3 is a side elevation of the embodiment of FIG. 1, showing a first partial bristle pattern, containing only the bristle tufts as indicated in FIG. 3A, a top plan of the brush head, wherein each present bristle tuft is shown as a circle, the location of each missing bristle tuft is indicated by a cross (+); 
     FIG. 4 is a side elevation of the embodiment of FIG. 1, showing a second partial bristle pattern, containing only the bristle tufts indicated in FIG. 4A, a top plan of the brush head, with the same notation as FIG.  3 A. 
     FIG. 5 is a top plan of the brush head of the embodiment of FIG. 1, each bristle tuft is shown as a circle. 
     FIG. 5A is a cross-sectional elevation showing the bristle tufts across the cross-section A—A in FIG. 5, in the direction indicated. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1, a perspective view of a toothbrush  10 , showing a portion of an elongated handle  12  and an elongated head  14  with two groupings of bristle tufts  16 ,  18  extending from the face  20  thereof, which two bristle tuft groupings  16 ,  18  embody the features and construction of this invention. The bristle tufts within each of the two groupings  16 ,  18  are designed to be flexible, so as to easily conform to the uneven topography of the teeth. Such flexible bristle tufts preferably have a round cross-section of from about 0.05 (1.27 mm) to about 0.01 inches (0.254 mm) in diameter, with corresponding cross-sectional areas of about 0.001 sq. inches (0.00645 cm 2 ) to about 0.006 sq. inches (0.03871 cm 2 ). The bristle tufts within each of the two groupings  16 ,  18  are generally arranged in rows which are substantively transverse to the longitudinal axis C—C of the head  14  and wherein a row may include only one bristle tuft. While not completely shown, the reader will understand that the handle  12  extends further. 
     The bristle trim of each grouping  16 ,  18  of bristle tufts within the present invention contains at least one radius of curvature, to better conform to the curved topography of the dentiture. It is preferred that the first grouping  16  have a bristle trim with a curved side profile, divided into a front portion and a rear portion having different radii of trim curvature. The front portion having a first radius of curvature R 1  which is convex with respect to the brush face  20 , arced toward the toe  22  of the brush head  14 , see FIG.  2 . This first radius of curvature R 1  should be from about 4 to about 6 mm and involve only the bristle trim of the first 2 or 3 rows of bristles proximate to the toe  22  of the toothbrush  10 . It is preferred that the rear portion have a second radius of curvature R 2  be from about 10 to about 20 mm, arced away from the toe  22  of the toothbrush  10 , convex with respect to the brush face  20 , see FIG.  2 . These radii, R 1  and R 2 , enhance the ability of the first grouping  16  of bristle tufts to scrub and clean the curved interproximal areas, especially, as the user brushes the posterior teeth, when the user is often holding the toothbrush  10  at a slight angle to the facial tooth surfaces. 
     As shown in FIG. 5A, a cross-section of the second grouping  18  as indicated in FIG. 5, the preferred bristle trim of the second grouping  18  contains a radius of curvature R 3  in the form of a channel oriented longitudinally therethrough. This channel has a radius of curvature R 3  of from about 0.0787 inches (2 mm) to about 0.2362 inches (6 mm) and most preferably about 0.1181 inches (3 mm). This channel enhances the ability of the second grouping  18  to conform to the curved segments of the tooth between the facial and occlusal, and lingual and occlusal surfaces; which conformation is especially important while brushing the posterior teeth. 
     Referring to FIG. 2, a side elevation view of the present invention, it can be seen that the density of the bristle tufts within the first grouping  16  of bristle tufts, most proximate to the toe  22  of the head  14 , is greater than the density of the bristle tufts in the second grouping  18  of bristle tufts, which is closest to the handle  12 . The relatively greater tuft density within the first grouping  16 , facilitates that groupings ability to scrub the relatively flat facial, lingual and occlusal tooth surfaces for enhanced cleaning. Within the first grouping  16 , the spacing between the outer bristle tufts closest to the sides of the head  14  (hereinafter the peripheral tufts) is preferably from about 0.0787 inches (2 mm) to about 0.1181 inches (3 mm), a relatively denser spacing which still facilitates the desired flexibility discussed above. The other, interior, bristle tufts within the first bristle grouping  16 , are preferably disposed along the longitudinal axis C—C and centered so as to be medially between the peripheral tufts. 
     In the present invention, the lesser bristle tuft density within the second grouping  18 , is such that the longitudinal spacing, along the brush head  14 , between the peripheral tufts is preferably from about 0.1378 inches (3.5 mm) to about 0.1575 inches (4.0 mm) center-to-center. Transversely, across the head  14 , the center-to-center spacing between bristle tufts in the second grouping  18  is preferably at least about 0.0787 inches (2 mm). The interior bristle tufts within the second grouping  18  are also preferably located such that their centers are transversely aligned with each other, but transversely offset by at least about 0.00787 inches (0.2 mm) from the centers of the peripheral tufts, which are themselves transversely aligned with each other. The lower tuft density within the second grouping, combined with the natural flexibility of the bristle tufts and the slight staggering of the bristle tufts across the brush head  14 , facilitates the penetration of the bristle tufts into the interproximal areas. Further, this combination of features within the second grouping  18  enhances the freedom of the tufts to flex without mutual interference, such that they exhibit greater movement and splay, to flick and otherwise dislodge food particles trapped in the interproximal areas. 
     Referring to FIGS. 3 and 4, side elevations of the embodiment of FIG. 1, showing partial bristle patterns containing only the bristle tufts, respectively, indicated in FIGS. 3A and 4A, top plan views of the brush head; wherein, each present bristle tuft is shown as a circle and each missing/non-shown bristle tuft is indicated by a cross (+). As shown in FIG. 3, the bristle tufts within the first grouping are preferably angled, at an angle α, toward the toe  22  of the toothbrush  10 . The angle ax is from about 3 to about 7 degrees from the perpendicular in relation to the brush face  20 , most preferably about 5 degrees from the perpendicular. This angle allows the bristle tufts of the first grouping  16  to be lodged more perpendicularly to the facial tooth surfaces as the brush is moved into and out-of the oral cavity during brushing, when the user is often holding the toothbrush  10  at a slightly acute angle to the facial tooth surfaces. 
     Continuing to refer to FIGS. 3 and 4, and observing the second grouping  18 , wherein the peripheral bristle tufts are acutely angled, at an angle β, toward the toe  22  of the toothbrush  10  and the interior bristle tufts are acutely angled, at an angle φ, toward the handle  12  of the toothbrush  10 . These bristle tufts are preferably angled, in their respective directions, at an angle β or φ, of from about 8 to about 15 degrees from the perpendicular in relation to the brush face  20 . These angles allow the bristle tufts to better penetrate the interproximal areas as the toothbrush is moved into and out-of the oral cavity during brushing. 
     An alternative embodiment of the present invention is such that the rows of angled bristle tufts in the second grouping are alternatingly longer and shorter, i.e. higher and lower with respect to the face  20  of the toothbrush  10 . It is preferred that the longer rows of angled bristle tufts be at least 0.0394 inches (1 mm) and more preferably about 0.0591 inches (1.5 mm) to about 0.0787 inches (2 mm) greater in length than the shorter rows of angled bristle tufts; such that, for example, the bristle tufts within the shorter rows may be 0.3937 inches (1 cm) in length and the bristle tufts within the longer rows may be 0.4724 inches (1.2) cm in length. This alternating pattern of bristle lengths within the second grouping allows the longer rows to more deeply penetrate the interproximal spaces for cleaning therein, while the adjacent shorter rows do not abut against the various tooth surfaces to restrict such penetration. 
     Any conventional flexible bristle material may be utilized in the present invention. Nylon and polyester are preferred bristle materials, with nylon being the most preferred. A preferred brand of nylon, 6, 12 nylon, is available from E.I. DuPont de Nemours and Company of Wilmington, Del. under the tradename of TYNEX®. 
     In addition to being flexible, it is preferred that he bristles within the present invention be soft enough to clean the gingival margin and remove debris and plaque without causing irritation and bleeding. It is preferred that the bristles be end-rounded and have a diameter be between about 0.003 inches (0.0762 mm) and about 0.012 (0.3048 mm) inches, most preferred between 0.005 inches (0.127 mm) and 0.008 inches (0.2032 mm). 
     The bristles may be implanted in the toothbrush face  20  in tufts using either typical staple technology or using more modern non-staple technology as disclosed in U.S. Pat. Nos. 4,635,313, 4,637,660, 4,954,305, 5,045,267, 5,390,984, 5,533,791, 5,609,890, and 5,823,633. Such non-staple technology involves processes wherein the bristle tufts are fused into the brush head  14 , by heating both the bristle tufts and the brush head  14 , which are then brought together; or, wherein the ends of the bristle tufts are pre-positioned in an injection mold prior to the introduction of the toothbrush material, which toothbrush material is subsequently injected about the ends of the bristle tufts, locking the bristle tufts in place in the toothbrush head  14 .