NON-PLANAR BRUSH

Abstract

Disclosed is a brush having a generally arc-shaped base surface with a plurality of bristles that are grouped together into arcuate or splayed tufts that are seated with cavities on the base surface and extend outwardly therefrom.

Description

TECHNICAL FIELD

The present invention relates generally to a brush useful for oral care. More particularly, the invention relates to a toothbrush that has splayed or arcuate tufts of bristles extending from an arc-shaped base surface.

BACKGROUND

Conventional toothbrushes are typically manufactured by attaching groups of bristles referred to as “tufts” to the plastic head of the toothbrush. The tufts can be attached in many ways. In one common approach, the tufts are made of a bundle of bristles that have been folded at their midpoint into a U-shaped configuration and mechanically fastened into position on the head of the toothbrush. Usually, a staple is used at the folded part of the bundle, which is embedded within an aperture or cavity provided in the head of the toothbrush. These bristles are normally aligned in a single direction and are generally parallel to one another.

One potential drawback of this conventional design is that the tufted bristles are bundled closely together and thus are not free to bend or flex independently because each bristle's movement is constrained at least partially by the surrounding bristles. Thus, the bristles may not be able to independently follow the irregular contours along the tooth's surface.

Another potential disadvantage of many conventional toothbrush designs is that the tufted bristles produce a generally flat bristle surface, i.e. the surface defined by the ends of the bristles is a generally flat or planar surface. In such a flat surface, the ends of the tufts can prevent nearby bristles from penetrating into groves in the teeth. In addition, the interproximal access of the bristles may be limited by the bulky diameter of the densely packed tufts.

SUMMARY

The present invention features a brush comprising a generally arc-shaped base surface with a plurality of bristles that are grouped together into tufts that extend outwardly from the base surface. In one embodiment of the invention, the bases of the tufts are situated inside of tuft cavities on the base surface and the bristles protrude out from the base surface through the open ends of the tuft cavities. The individual tufts are typically splayed or arcuate, i.e. the free ends of the bristles of an individual tuft form an arc shape when viewed in cross section. In some implementations of the invention, the tufts are sufficiently splayed so that one or more bristles from adjacent tufts are in contact. Typically, multiple bristles from a tuft are in contact with bristles from multiple adjacent tufts. In some embodiments bristles from a splayed tuft may be in contact with bristles from at least four adjacent tufts, or even six or more adjacent tufts.

Typically, the tuft cavities are shaped in a manner that leads to the splaying of the tufted bristles. For example, in some implementations of the invention, at least one of the tuft cavities has a cross-sectional area that is greatest at the open end and decreases towards the closed end of the cavity. This configuration may be accomplished by providing a tuft cavity that is angled or beveled outward at or near the opening of the cavity. Such cavities may have, for example, a substantially conical or truncated conical shape.

In some embodiments of the invention, the tufted bristles, especially the bristle portions that extend outside of the tuft cavity, are straight, i.e., substantially linear. In addition, the splaying typically begins at or beneath the open end of the tuft cavities such that the bristles are already diverging from one another as they extend out of the tuft cavity.

The tufts and/or tuft cavities may be arranged in rows or in patterns on the base surface. Alternatively, the tufts and/or tuft cavities may be distributed randomly over the base surface.

In some implementations of the invention, the plurality of tufts have bristles with free ends that define an arcuate bristle surface. In further embodiments, the arc-shaped base surface may be sufficiently rounded or circular such that a first bristle extends outward from the base surface at an angle that is greater than 180 degrees relative to a second bristle that extends outward from the base surface.

The brush of the invention may be useful for any of a variety of tasks for which brushes are commonly employed, e.g., cleaning and/or scrubbing of a surface, application of a coating material onto a surface, brushing hair, etc. The brush of the invention is particularly well-suited for use as a toothbrush. In such implementations, the toothbrush typically comprises a handle with a head at one end, the heading being sized to fit into a human mouth and having a brushing surface as described above.

As used herein, “a” or “an” means “at least one” or “one or more” unless otherwise indicated. In addition, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a composition containing “a compound” includes a mixture of two or more compounds.

As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. In addition, the terms “comprises”, “comprising” and variations thereof do not have a limiting meaning where these terms appear in the description and claims.

The recitation herein of numerical ranges by endpoints is intended to include all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). In addition, Unless otherwise indicated, all numbers expressing quantities, or measurement of dimensions, properties, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings of the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviations found in their respective testing measurements.

The above summary is not intended to describe each embodiment or every implementation of the invention. Other embodiments, features, and advantages of the present invention will be apparent from the following detailed description thereof, from the drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a toothbrush according to the present invention.

FIG. 2 is a perspective view an arc-shaped base surface with a plurality of tufted bristles extending outwardly therefrom.

FIG. 3 is a perspective view of an arc-shaped base surface showing a plurality of tuft cavities arranged in rows.

FIG. 4 a is a perspective view of an arc-shaped base surface showing a plurality of tuft cavities randomly distributed over the base surface.

FIG. 4 b is a perspective view of an arc-shaped base surface showing a plurality of splayed tufts randomly distributed over the base surface.

FIG. 5 is a cross-section view of a brush according to one embodiment of the invention in which the arc-shaped base surface has a plurality of splayed bristle tufts extending outwardly therefrom and the reverse side of the brush is also arc-shaped.

FIG. 6 is a cross-section view of a brush according to one embodiment of the invention in which the arc-shaped base surface has a plurality of splayed bristle tufts extending outwardly therefrom and a portion of the base surface at either side of the brush is flat or planar.

FIG. 7 is a cross-section view of a brush according to one embodiment of the invention in which the arc-shaped base surface has a plurality of splayed bristle tufts extending outwardly therefrom and the reverse side of the brush is substantially flat or planar.

FIG. 8 is a cross-section view of a brush according to one embodiment of the invention in which the arc-shaped base surface is rounded so that bristles at one side of the base surface extend outwardly at an angle greater than 180 degrees relative to bristles that extend outwardly from the opposite side of the base surface.

FIG. 9 is a cross-section view of a tuft cavity that has a conical or V shape.

FIG. 10 is a cross-section view of a tuft cavity that has a truncated conical or V shape.

FIG. 11 is a cross-section view of a tuft cavity that is angled or beveled outward near the open end of the tuft cavity.

FIG. 12 is a cross-section view of a tuft seated in a tuft cavity.

FIG. 13 a is a top view of a brush head having a plurality of tuft cavities with staples that are oriented at a variety of different angles relative to the longitudinal axis of the brush.

FIG. 13 b is a top view of brush head having a plurality of tuft cavities with different sizes and shapes.

FIG. 14 is a cross-section view of an arc-shaped base surface showing a bristle extending therefrom at an angle relative to a plane that is tangential to the arc-shaped base surface.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings that show, by way of illustration, specific embodiments or implementations of the invention. It is to be understood that other alternative embodiments and implementations may be used, and structural changes and/or other modifications or alterations may be made to the embodiments depicted in the figures without departing from the spirit and scope of the present invention.

FIG. 1 depicts one illustrative embodiment of a toothbrush according to the present invention. The toothbrush includes a handle 10 with a proximal end 12 and a distal end 14 opposite the proximal end 12. A longitudinal axis 16 extends from the proximal end 12 to the distal end 14.

The toothbrush may be made of any suitable material known in the art, including polymeric materials (e.g. polypropylene, cellulosics, polyesters, acrylics and various other plastic polymers), metal, wood, fiberglass, etc., and combinations thereof. The handle 10 may be any suitable shape, e.g., rectangular, cylindrical, etc. Typically, the handle 10 is sized and/or shaped such that it conforms with the hand of user.

The toothbrush handle 10 may further include a flexible member proximate the distal end 14 as described in U.S. Pat. No. 6,003,189 to Falleiros et al. entitled “Toothbrush.” The flexible member may flex if a user applies excessive force to the distal end 14 of the toothbrush handle 10 while brushing.

The toothbrush includes a head 20 proximate the distal end 14 of the toothbrush handle 10. The head includes a brushing portion 36 that has a base surface 22 and a plurality of bristles 55 that are bundled together into tufts and attached to the base surface 22 using any suitable technique known in the art, e.g., mechanical fasteners, adhesives, welding (thermal or chemical), etc. In one embodiment, the head 20 may be removably attached to the handle 10 as is further described herein. Although the head 20 may be provided as a separate unit attached to the handle 10, the bristles 55 may alternatively be embedded directly into the handle 10, in which case the head 20 is integral to the handle 10.

The head 10 may take any suitable shape, e.g., rectangle, oval, circle, diamond, parallelogram, etc., and may be made of any suitable material, e.g., polymeric materials (e.g., plastics), metal, wood, fiberglass, etc., and combinations thereof.

The brushing portion 36 includes a base surface 22 at least part of which is arc-shaped. The term “arc-shaped” or “arcuate” when used herein in reference to the base surface means that a cross-section view of the longitudinal axis of the base surface is generally arc shaped, although in some implementations of the invention the base surface 22 may have a flat or planar portion, that is typically located proximal to the edges 26 of the surface, as is shown in FIG. 6.

Typically the base surface 22 forms an acruate cylindrical segment as shown in FIGS. 2, 3, 4a, and 4b. Although the arcuate cylindrical segment is defined by an axis that would generally align with the longitudinal axis of the handle 10, such as arrangement may not be required for all implementations. For example, it would be possible for the longitudinal access of the base surface to be perpendicular to the longitudinal axis of the handle.

The arc-shaped base surface 22 typically has a plurality of tuft cavities 50 that may be arranged in rows, as is depicted in FIG. 3, or in some other pattern on the base surface 22. Alternatively, the tuft cavities 50 may be distributed randomly over the base surface 22, i.e., the distances between the centers of the cavities may be variable, as is shown in FIG. 4a. “Random or variable” in this sense does not require that each brush has a unique arrangement of bristles and/or tufts, simply that the selected arrangement of bristles and/or tufts have no discernable pattern. Thus multiple brushes being machined in some manner could have the same “random” arrangements.

Referring now to FIG. 5 to FIG. 8, the brushing portion includes bristles 55 that protrude from the base surface 22. The bristles 55 are grouped together into tufts 60 that are seated in the tuft cavities 50. As depicted in FIG. 12, each tuft 60 has a base portion 58 positioned within the tuft cavity 50 and a free portion 57 that extends outside of the tuft cavity 50. Typically, the free portion 57 of the tuft 60 that is outside of the tuft cavity 50 is longer than the base portion 58 that is inside the tuft cavity 50.

The bristles 55 may be made of any suitable material, e.g., nylons, PBT, PVDF, acetyl resins, polyesters, fluoropolymers, polyacrylates, polysulfones, other polymeric materials, other polymeric materials and the like, and mixtures thereof. The bristles 55 may include additional materials that are either mixed throughout the bristle or that are coated onto the outer surfaces of the bristles, e.g., abrasives, antimicrobial agents, whitening agents, coatings to improve flocking, etc,

Each bristle 55 may be any suitable shape, e.g., cylindrical, conical, rectilinear, etc. Each bristle 55 may further include a tapered end distal from the base surface. In an alternative embodiment, the ends of the bristles 55 may be rounded.

The bristles 55 may each be of the same length, i.e. all of the bristles terminate at substantially the same distance from the base surface 22. In some implementations, the bristle 55 may include a length from the base surface to a distal end of the bristle of about 15 mm or less, more typically about 10 mm or less. Most typically, each bristle has a length of about 4 mm to about 6 mm that extends above the base surface.

Bristle diameter may vary as desired based on a variety of factors such as the materials used for the bristles, the length of the bristles, etc. A suitable range for bristle diameter may be, for example, from about 0.05 mm to about 0.25 mm, although bristles with diameters outside of this range may also be used in connection with brushes according to the present invention. In other alternatives, the brushes may include bristles of two or more different diameters arranged in selected patterns according to diameter or randomly dispersed in tufts over the brushing portion 36.

The stiffness of the bristle may also be varied depending on the desired application. For example, suitable bristle stiffness for a toothbrush is known in the art and described, for example, in U.S. Pat. No. 6,058,541. Since the brush of the present invention has tufts that are splayed and thus have greater freedom of motion as compared to tightly-packed tufts in which the bristles are in a parallel arrangement, the brush may, in some implementations, be constructed with stiffer bristles than those used in conventional brushes while still retaining the ability to penetrate into groves in between a patient's teeth and gums.

In the embodiments depicted, for example, in FIG. 5 to FIG. 7, the free end of the bristles 55 from multiple tufts 60 define an arcuate cylindrical bristle surface 40 spaced from the base surface 22. The acruate bristle surface 40 may facilitate implementation of the Bass brushing technique as described, for example, in U.S. Pat. No. 5,749,381 to Butler et al. entitled “Toothbrush for Implanting the Bass Brushing Technique.” Alternatively, other non-planar bristle surface shapes (e.g. V-shape, serrated, corrugated, etc.) may be used.

FIG. 8 shows a cross-section view of an embodiment in which the base surface 22 has a sufficiently circular shape such that the arc created by the base surface is defined by an angle that is greater than 180 degrees. Typically, the tufted bristles are disposed across nearly the full length of the arc so that bristles on one side of the arc extend outward from the base surface at an angle θ that is greater than 180 degrees relative to bristles that extends outward from the base surface on the other end of the arc.

The tufts of the brushing portion 36 may be formed using any suitable technique known in the art. For example, a tuft may be made by grouping together straight monofilaments and then bending or folding the monofilaments in half (thereby providing two bristles for each monofilament) and fastening the tuft to the base surface at the folded part of the bundle, which is embedded within a tuft cavity in the base surface. The number a filaments per tuft will vary depending on a number of factors, including the size and shape of the tuft cavity, the number of tufts on the brush, and the desired bristle density. In addition, different tufts may be of different sizes and/or have different numbers of tufts. Typically, the number of filaments per tuft ranges from about 2 to about 50.

As shown in FIG. 12, a mechanical fastener 80 (e.g., a staple) is typically used to secure the tuft 60 to the base surface 22 at the bottom of the closed end 70 of a tuft cavity 50. The fastener 80 may positioned within the cavity in a uniform manner (i.e., at the same angle or orientation relative to the longitudinal axis of the brush) or be at a variety of different angles or orientations relative to the longitudinal axis of the brush (e.g., some perpendicular, some parallel, some in between, etc.), as is shown in FIG. 13a. The fastener 80 may be made of any suitable material, including metal, plastic, wood or any of a variety of synthetic or natural materials. Alternatively, any other suitable technique known in the art (e.g., welding on or in the base surface, injection molding, adhesive attachment, punch-through attachment, hot-tufting, flocking, etc.) may be used to attach the tufts to the base surface.

In a typical implementation of the invention, the tufts are splayed so that at least one bristle 55 from at least one tuft 60 is touching or overlapping at least one bristle from at least one adjacent tuft. As used herein, “splayed” means that the bristles of an individual tuft or bundle diverge outward from a point at or near the base of the tuft or bundle. In some embodiments of the invention, the base of the tuft is situated within a tuft cavity and the splaying begins at a point inside the tuft cavity so that the bristles are already diverging at or before the point at which they exit the tuft cavity. Typically, the splaying is the result of bristles being positioned at an angle relative to other bristles (i.e. arrayed in a non-parallel arrangement within the tuft cavity) as opposed to resulting from the curving or bending of the bristles.

As shown in FIG. 14, each of the bristles 55 extends outwardly from the base surface 22 at an angle α relative to a plane 88 that is tangential to the base surface at the point the bristle impinges the base surface. The angle α is typically anywhere from about 90 degrees to about 20 degrees relative to the plane 88. Different bristles may protrude from the base surface at different angles. For example, one bristle of a tuft may protrude at a 70 degree angle while another bristle from the same tuft may protrude at a 90 degree angle (i.e. perpendicular) with respect to the base surface. Yet another may protrude at an 80 degree angle, etc.

Furthermore, each individual tuft may be splayed or fanned out in such a manner that the bristle surface formed by an individual tuft forms an acruate tuft surface 42 as shown in FIG. 12. In some embodiments, a plurality of arcuate tufts 60 may, in turn, be arranged so that the entire bristle surface 40 is acruate as depicted, for example, in FIG. 6. In other embodiments, the collection of arcuate tufts may form a different type of non-planar bristle surface.

Splaying of a tuft may be accomplished by providing tuft cavities that are shaped in a manner that induces the bristles to diverge or spread out as they exit the tuft cavity. In general, shapes in which the tuft cavity has a cross sectional area that is greatest at the open end and decreases towards the closed end of the cavity will lead to splaying of tufted bristles. An example of a tuft cavity having this configuration is shown in FIG. 9, which depicts a cross-section view of a conical tuft cavity. The open end 75 of the tuft cavity 50 has a diameter d₁. The side wall 65 of the tuft cavity is angled so that the diameter of the tuft cavity decreases towards the bottom of the closed end 70 and increases towards the open end 75, with the diameter of the tuft cavity being greatest at the open end 75. The depth h₁, of the cavity may be the substantially the same for all cavities, or may vary from cavity to cavity. In some implementations, a shallow cavity may be desirable since it promotes wider splaying of the bristles.

FIG. 12 depicts a tuft 60 seated within the tuft cavity 50 of FIG. 9, and illustrates how the shape of the tuft cavity 50 promotes splaying. As the bristles 55 extend outward from the bottom of the closed end 70 of the tuft cavity, the outer bristles generally follow the angled path of the side wall 65, and thus follow diverging paths as they exit the tuft cavity 50. Bristles in the middle of the tuft 60 extend out of the tuft cavity 50 at various angles between the outer bristles, thereby resulting in a splayed or acruate tuft.

A similar result can be achieved using a tuft cavity that has a truncated cone shape, a cross-sectional view of which is shown in FIG. 10. The tuft cavity 50 of FIG. 10 has a height h₂ and a diameter d₃ at the open end 75 that is greater than the diameter d₂ at the closed end 70 of the cavity. The side wall 65 is sloped such that the diameter continually increases towards the open end 75; however, in other embodiments the diameter may increase in a step-wise fashion.

FIG. 11 shows yet another version of the tuft cavity 50 in which the bottom length h₃ of the cavity is cylindrical with a side wall 68 that is roughly perpendicular to the base surface, and an upper length h₄ that has a side wall 65 that is beveled or angled outward thus providing for a diameter d₅ at the open end 75 that is greater than the diameter d₄ at the closed end 70. Because the lower portion of the cavity has a substantially uniform diameter d4, this shape generally results in a lesser degree of splaying than the embodiments depicted in FIG. 9 and FIG. 10.

Other techniques for splaying tufts may used either in combination with or as alternatives to providing a suitably shaped tuft cavity. For example, tufts may be also be splayed by using staples that pinch the bristles in a manner that promotes splaying, etc. Alternative means for splaying tufts are particularly suitable for embodiments of the invention in which the tufts are directly fused, bonded, or otherwise attached to the exterior of the base surface without being seated in tuft cavities.

The splayed tufts may be disposed on the base surface in any desired arrangement. For example, the tufts may be distributed in rows and/or columns (see, e.g., FIG. 2) or in other patterns on the base surface 22, or alternatively, may be distributed randomly over the base surface 22, i.e. the distances between the centers of the tufts may be variable (see, e.g., FIG. 4b).

The tuft cavities 50 may all be of about the same size and shape (see, e.g., FIG. 3), or the tuft cavities may have different sizes and/or shapes (see, e.g., FIG. 13b).

Although the opposing side 24 of the brushing portion 36 is depicted in FIGS. 5, 6 and 7 without any bristles extending therefrom, in some implementations of the invention, it may be desirable to included tufted bristles on this surface as well. The opposing side 24 may be arc-shaped in a manner similar to that of the support surface (as is shown in FIG. 5), or it may be flat or planar (as is shown in FIGS. 6 and 7).

Although the present invention has be described with reference to a toothbrush, it should be understood that the invention can encompass other types of brushes, including brushes for cleaning floors, tile, mechanical parts, skin, hair, etc. Various modifications and alterations to the invention, for example changes in bristle size, shape, materials, etc. to adapt the brush for alternative applications, will be readily apparent to those skilled in the art without departing from the scope and spirit of this invention. It should be understood that the invention is not intended to be unduly limited by the specific embodiments and examples set forth herein, and that such embodiments and examples are presented merely to illustrate the invention, with the scope of the invention intended to be limited only by the claims attached hereto.

The complete disclosures of the patents, patent documents, and publications cited herein are hereby incorporated by reference in their entirety as if each were individually incorporated.

Claims

1. A brush comprising an arc shaped base surface comprising a plurality of substantially linear bristles that are grouped together into tufts that extend out from the base surface and are splayed so that one or more bristles from adjacent tufts are in contact.

2. The brush of claim 1, wherein the brush is a toothbrush.

3. A brush comprising: (a) an arc-shaped base surface comprising a plurality of tuft cavities each having an open end and a closed end, and(b) a plurality of bristles that are grouped together into tufts that are seated within the tuft cavities so that the bristles extend out from the base surface through the open ends of the tuft cavities, the tufts being sufficiently splayed so that one or more bristles from adjacent tufts are in contact.

4. The brush of claim 3, wherein at least one of the tuft cavities has a cross sectional area that is greatest at the open end and decreases towards the closed end of the cavity.

5. The brush of claim 3, at least one of the tuft cavities has a substantially conical shape.

6. The brush of claim 3, wherein at least one of the tuft cavities has a shape that promotes splaying of a tuft.

7. The brush of claim 3, wherein the bristle portions that extend outside of the tuft cavity are substantially linear.

8. The brush of claim 3, wherein the tufts are splayed at or beneath the open ends of the tuft cavities.

9. The brush of claim 1, wherein the tufts are distributed randomly over the arc-shaped base surface.

10. The brush of claim 3, wherein the tuft cavities have different sizes and/or shapes.

11. The brush of claim 1, wherein the brush comprises a first bristle that extends outward from the base surface at an angle that is greater than 180 degrees relative to a second bristle that extends outward from the base surface.

12. A toothbrush comprising: (a) a first end comprising a handle, and(b) a second end comprising a head that is sized to fit into a human mouth, the head comprising(i) an arc-shaped base surface comprising a plurality of tuft cavities each having an open end and a closed end, and(ii) a plurality of bristles that are grouped together into tufts that are seated within the tuft cavities so that the bristles extend out from the base surface through the open ends of the tuft cavities, the tufts being sufficiently splayed so that one or more bristles from adjacent tufts are in contact.

13. The toothbrush of claim 12, wherein at least one of the tuft cavities has a cross sectional area that is greatest at the open end and decreases towards the closed end of the cavity.

14. The toothbrush of claim 12, at least one of the tuft cavities has a substantially conical shape.

15. The toothbrush of claim 12, wherein at least one of the tuft cavities has a shape that promotes splaying of a tuft.

16. The toothbrush of claim 12, wherein the bristle portions that extend outside of the tuft cavity are substantially linear.

17. The toothbrush of claim 12, wherein the tufts are splayed at or beneath the open ends of the tuft cavities.

18. The toothbrush of claim 12, wherein the tuft cavities are distributed randomly over the arc-shaped base surface.

19. The toothbrush of claim 12, wherein the tuft cavities have different sizes and/or shapes.

20. The toothbrush of claim 12, wherein the head comprises a first bristle that extends outward from the base surface at an angle that is greater than 180 degrees relative to a second bristle that extends outward from the base surface.

21. A brush comprising: (a) an arc-shaped base surface comprising a plurality of conical tuft cavities each having an open end and a closed end, and(b) a plurality of bristles that are grouped together into arcuate tufts that are seated within the tuft cavities so that the bristles extend out from the base surface through the open ends of the tuft cavities.

22. The brush of claim 21, wherein the brush is a toothbrush.

23. The brush of claim 21, wherein the bristle portions that extend outside of the tuft cavity are substantially linear.

24. The brush of claim 21, wherein the tufts are splayed at or beneath the open ends of the tuft cavities.

25. The brush of claim 21, wherein the tuft cavities are distributed randomly over the arc-shaped base surface.

26. The brush of claim 21, wherein the tuft cavities have different sizes and/or shapes.

27. The brush of claim 21, wherein the head comprises a first bristle that extends outward from the base surface at an angle that is greater than 180 degrees relative to a second bristle that extends outward from the base surface.