Abstract:
A dental hygiene device such as an interdental brush includes a handle, a brush head having bristles extending therefrom, and a neck portion extending between the brush head and the handle. The neck portion of the dental hygiene device is configured to provide two modes of operation, a first cleaning mode of operation wherein the brush head contacts the teeth at a first pressure for a given application pressure, and a second cleaning mode of operation wherein the brush head contacts the teeth at a second pressure, greater than the first pressure, for the same given application pressure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation of U.S. patent application Ser. No. 13/103,866, filed May 9, 2011, now U.S. Pat. No. 9,131,768. The above referenced application is hereby incorporated by reference. 
    
    
     BACKGROUND 
     An interdental brush is a dental hygiene device that can brush interdental spaces in the mouth. Interdental brushes typically include a handle and a brush head having a plurality of bristles that typically are constructed from short fibers. The brush head and bristles are sized and configured to be insertable into interdental spaces for cleaning thereof. 
     SUMMARY 
     In some aspects, an interdental brush includes a handle, a brush head having bristles extending therefrom, and a neck portion extending between the brush head and the handle. The neck portion defines a longitudinal axis and has a first bending stiffness when subject to loading in a first direction that is substantially perpendicular to the axis, and a second bending stiffness when subjected to loading in a second direction that is substantially perpendicular to the axis. The first bending stiffness being less than the second bending stiffness. 
     In other aspects, a neck for a dental hygiene device defines a longitudinal axis and includes a central portion formed of a first material, and a periphery portion extending along and adjacent to the central portion. The periphery portion is formed of a second material. The neck has a first bending stiffness when subject to loading in a first direction perpendicular to the axis and a second bending stiffness when subject to loading in a second direction perpendicular to the axis. The first bending stiffness is less than the second bending stiffness. 
     In other aspects, an interdental brush includes a handle and a neck portion extending from the handle and defining a longitudinal axis. A brush head includes bristles extending from the brush head in a plurality of radial directions, and at least some of the bristles have a substantially triangular cross section. 
     In other aspects the invention provides for an interdental brush for cleaning teeth, the interdental brush including a handle, a neck portion extending from the handle, and a brush head coupled to and extending from the neck portion, the brush head including a stem from which a plurality of bristles extend in a diametrically opposed manner. The neck portion being configured to provide two modes of operation, a first cleaning mode of operation where the brush head contacts the teeth at a first pressure for a given input pressure, and a second cleaning mode of operation where the brush head contacts the teeth at a second pressure, greater than the first pressure, for the same given input pressure. 
     In other aspects, an interdental brush includes a neck portion extending from the handle and having a first axis and a second axis, the neck portion having a first bending stiffness when subject to loading about the first axis, and a second bending stiffness when subject to loading about the second axis, the first bending stiffness being less than the second bending stiffness. The interdental brush also includes a brush head coupled to and extending from the neck portion, the brush head configured to be inserted into interdental spaces for cleaning thereof, and a handle, the handle having a first set of grips substantially aligned with the first axis of the neck portion and a second set of grips substantially aligned with the second axis. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a dental hygiene device. 
         FIG. 2  is a side view of the dental hygiene device of  FIG. 1   
         FIG. 3  is a front view of the dental hygiene device of  FIG. 1 . 
         FIG. 4  is a section view of a bristle of the dental hygiene device of  FIG. 1 . 
         FIG. 5  is cross section view taken along line  5 - 5  of  FIG. 1 . 
         FIG. 6  is an enlarged perspective view, showing an alternative configuration for a neck portion of the dental hygiene device of  FIG. 1 . 
         FIG. 7  is a section view taken along  7 - 7  of  FIG. 6 . 
         FIG. 8  is a side view of the neck portion of  FIG. 6 . 
         FIG. 9  is a front view of the neck portion of  FIG. 6 . 
         FIG. 10  is a perspective view of an alternative dental hygiene device. 
         FIG. 11  is a perspective view of another alternative dental hygiene device. 
     
    
    
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of a dental hygiene device  10  in the form of an interdental brush. The device  10  includes a handle  20 , a brush head  30 , and an elongated neck  40  positioned between the handle  20  and the brush head  30 . The neck  40  defines a longitudinal axis  50 , and, in the illustrated construction, the handle  20  and the brush head  30  are substantially aligned with the longitudinal axis  50 . 
     Referring also to  FIGS. 2 and 3 , the handle  20  is generally hourglass-shaped, with bulbous upper and lower portions  60  and  70 . In the illustrated embodiment, the upper portion  60  includes two tactily identifiable upper grip surfaces  80 , and the lower portion  70  also includes two tactily identifiable lower grip surfaces  90 . Each grip surface  80 ,  90  is substantially elliptical. The grip surfaces  80 ,  90  are positioned on opposite sides of the respective upper and lower portions  60 ,  70  of the handle  20 . The upper and lower grip surfaces  80  and  90  are alternatingly arranged about the handle  20 . In other words, if the handle  20  is divided into imaginary quadrants, the first and third quadrants each have a lower grip surface  90  but not an upper grip surface  80 , and the second and fourth quadrant each have an upper grip surface  80  but not a lower grip surface  90 . In one embodiment, the handle measures about 5.5 cm in length and about 0.7 cm in diameter. 
     With continuing reference to  FIGS. 1-3 , the upper and lower grip surface  80  and  90  are “louvered,” including a plurality of fins or ribs or lateral slots  100 . In the illustrated embodiment, the fins  100  are substantially chevron-shaped with the apex of each chevron pointing towards the brush head  30 . In some embodiments, the fins  100  are evenly spaced along the handle  20  in a row. Furthermore, the fins  100  can be arranged such that they are angled away from the brush head  30 . Leaning the fins  100  in this way can help keep debris from collecting between the fins  100 , and can also improve a user&#39;s grip as the user inserts the brush head  30  into his or her interdental spaces. 
     The brush head  30  is mounted on the neck  40  by a bristle stem  110 . In the illustrated construction, the bristle stem  110  comprises intertwined or braided wires, but can also be formed of a suitable polymeric or other material, or can be integrally formed with the handle  20  and/or neck  40 . The bristle stem  110  can be secured in the neck  40  at a desired height using adhesive, fasteners, overmolding, insert molding, or any other suitable method. In the illustrated construction, the brush head  30  has a conical, domed, or pyramidal profile, with the apex of the brush head  30  pointing away from the bristle stem  110 . The shape or profile of the brush head  30  is determined by the length and relative positioning of the filaments and/or fibers that make up individual bristles  120  of the brush head  30 . Thus, for example, in other constructions the brush head  30  may be generally cylindrical, may include bristles  120  extending in a diametrically opposed manner from the bristle stem  110 , may include bristles  120  arranged in a “cross” pattern when viewed along the axis, and may include bristles of varying lengths, thicknesses, and stiffnesses. Among other things, the size and shape of the bristles  120  and brush head  30  can vary according to the desired depth of penetration into the interdental spaces. 
     Referring also to  FIG. 4 , at least some of the bristles  120  have a substantially triangular cross section. The triangular cross section of the bristles  120  has been found to enhance the cleaning effectiveness of the device  10 . The cross section of each bristle  120  can be an equilateral, isosceles, or scalene triangle. In the illustrated embodiment, the triangular cross section of each bristle filament  120  includes rounded apexes  130 . The filament  120  can be made of nylon or other suitable materials. 
     Referring to  FIG. 5 , the neck  40  is configured to be more elastically flexible in a first direction (e.g., the x-direction in  FIG. 5 ) than it is in a second direction (e.g., the y-direction in  FIG. 5 ). This variable flexibility is obtained by configuring the neck  40  to have a first bending stiffness when the brush head  30  is subjected to loading in the x-direction, and a second bending stiffness when the brush head  30  is subjected to loading in the y-direction, where the first bending stiffness is less than the second bending stiffness. For elongated beam-like structures such as the neck  40 , the bending stiffness in any direction can be approximated using well known engineering equations derived from beam theory, and is generally a function of the modulus of elasticity E of the material(s) and the area moment of inertia I of the cross section. As used herein, the terms “flexible,” “flexibility,” and the like refer to elastic flexibility whereby when the structure in question is deflected away from a static position due to application of a load and that load is subsequently removed, the structure&#39;s inherent elasticity causes it to return more or less to the static position without any appreciable permanent deformation. 
     The neck  40  illustrated in  FIG. 5  includes a central portion  150  formed of a first material having a first modulus of elasticity E 1  and a generally rectangular cross section. In some constructions the first material is a polypropylene and may be the same material from which at least portions of the handle  20  are formed. In this regard, the central portion  150  may be integrally molded with certain portions of the handle  20 . In other constructions, the central portion  150  may be coupled to the handle  20  using any suitable method. In the illustrated construction, the twisted or braided wires forming the bristle stem  110  are shown as being insert molded into the central portion  150 . Other materials also may be used to form the central portion  150  and/or the handle  20 , such as linear low density polyethylene, co-polyesters, or other suitable polymers. 
     A periphery portion  160  is adjacent to and surrounds the central portion  150 . The periphery portion  160  is formed of a second material having a second modulus of elasticity E 2  that is less than the modulus of elasticity E 1 . In some constructions, the second material is a thermoplastic elastomer that is overmolded onto the central portion, and may be the same material from which the grip surfaces  80 ,  90  are formed. In this regard, the periphery portion  160  may be overmolded onto the handle  20  and the central portion  150  during the same operation that overmolds the grip surfaces  80 ,  90  onto the handle  20 . In the construction of  FIG. 5 , the periphery portion  160  is generally cylindrical with the exception of the central area that is occupied by the central portion  150 . In other constructions, the periphery portion  160  may be coupled to the handle  20  and the central portion  150  in other suitable manners, such as by adhesives, sonic welding, or the like. 
     By way of example only, using the standard formula for calculating the area moment of inertia of a rectangular cross section (I=(b*h^3)/12, where b=the base of the rectangle and h=the height of the rectangle), the rectangular cross section of the central portion  150  provides an area moment of inertia Iy for bending moments about the y axis that is less than the area moment of inertia Ix for bending moments about the x axis. Similar results can be achieved by using a variety of different cross sections, such as an oval cross section, a diamond cross section, a properly selected I-beam cross section, a hollow-rectangular or oval cross section, and substantially any other cross section that results in different values for Iy and Ix. Although the periphery portion  160  of the construction illustrated in  FIG. 5  also contributes to the bending stiffness of the neck  40 , the majority of the overall bending stiffness of the neck  40  is established by the central portion  150  because of its larger modulus of elasticity E 1 . Some constructions of the device  10  may eliminate the periphery portion  160  in its entirety such that the bending stiffness of the neck  40  is determined solely by the central portion  150 . 
       FIGS. 6-9  illustrate an alternative construction of the neck  40   a  that also achieves different bending stiffnesses in different directions. The neck  40   a  includes an elongated central portion  150   a  and a periphery portion  160   a  extending adjacent to the central portion  150   a . Similar to the neck  40 , the central portion  150   a  of the neck  40   a  is made of a first material having a modulus of elasticity that is greater than the modulus of elasticity of a second material that forms the periphery portion  160   a . For example, the central portion  150   a  can be made of polymeric materials such as polypropylene, while the periphery portion  160   a  can be made of elastomeric materials such as thermoplastic elastomers. The central portion  150   a  can be integrally formed with the handle  20  or may be coupled to the handle  20  in a suitable manner. The periphery portion  160   a  can be over molded onto the central portion  150   a , or may be attached to the handle  20  and central portion  150   a  using other suitable techniques. 
     In the neck  40   a  of  FIGS. 6-9 , certain surfaces of the central portion  150   a  and the periphery portion  160   a  are coplanar, such that portions of the central portion  150   a  remain exposed. The periphery portion  160   a  has rounded edges  170 , so that the overall cross section of the neck  40   a  is generally rectangular with rounded corners (see  FIG. 7 ). As shown, the central portion  150   a  is sandwiched between two portions of the periphery portion  160   a , and a substantially ball-shaped tip  146  is formed from the second material. The rounded edges  170 , ball-shaped tip  146 , and softer thermoplastic elastomer materials (if used) can help provide a soft feeling to the gum tissue during use. 
     With reference to  FIG. 7 , the neck  40   a  is more flexible when subjected to bending in the y-direction than to bending in the x-direction because the overall cross section has different area moments of inertia Ix and Iy. Unlike the neck portion  40  of  FIG. 5 , where the difference in bending stiffness is attributable primarily to the structure of the central portion  150 , the difference in bending stiffness of the neck portion  40   a  of  FIG. 7  is attributable primarily to the selective positioning of the periphery portion  160   a  along only two sides of the central portion  150   a . Thus, the area moment of inertia Iy of the periphery portion  160   a  is greater than the area moment of inertia Ix of the periphery portion  160   a . As shown, the central portion  150   a  is square or nearly square, and therefore has area moments of inertia in about the x and y axes that are approximately the same. Positioning the periphery portion  160   a  along only two sides of the central portion more significantly increases the bending moment Iy of the overall cross section than the bending moment Ix of the overall cross section. The bristle stem  110  and brush head  30  (shown in phantom in  FIG. 6 ) are coupled to and extend from the ball-shaped tip  146 . 
     The configurations of the neck  40  of  FIG. 5  and the neck  40   a  of  FIGS. 6-9  are only two examples of possible neck constructions that provide the desired variation in bending stiffnesses in various directions. Other constructions are possible, including constructions configured to provide different bending stiffnesses in directions that are not necessarily perpendicular to one another as the x and y directions of  FIGS. 5 and 7  are. 
       FIGS. 10 and 11  illustrate alternative constructions of the handle  20 , which can be used with either of the above-described neck portions  40  or  40   a , or any of the various alternative constructions of the neck portions  40  or  40   a  described above. In the handle of  FIG. 10 , the upper and lower grip surfaces  80  and  90  are arranged on a same side of the handle  20 . In other words, if the handle  20  is divided into successive imaginary quadrants about the axis  50 , the first and third quadrants each have one or both of lower and upper grip surfaces  80 ,  90 , and the second and fourth quadrant each have no upper or lower grip surfaces  80 ,  90 . The upper and lower grip surfaces  80  and  90  may also be louvered with a plurality of fins or ribs  100  that are evenly spaced along the handle. The alternative handle  20  of  FIG. 11 , includes circumferentially-extending slots  200  extending various lengths around the upper portion  60 . The slots  200  can be evenly spaced along the handle  20  and so dimensioned that as an aggregate, the resulting upper grip surface  80  is substantially elliptical in the plan view. In the various constructions, the neck portion  40  or  40   a  is coupled to the handle  20  by a transition portion  190 . For example, the devices illustrated in  FIGS. 1-3 and 10  include a transition portion  190  in the form of a tapered bellows structure, the device illustrated in  FIGS. 6-9  includes a transition portion  190  in the form of a tapering radius structure, and the device illustrated in  FIG. 11  includes a transition portion  190  with circumferential grooves that are evenly spaced from one another. 
     In each of the various constructions discussed above, the neck  40  or  40   a  can be oriented relative to the handle  20  such that the upper grip portion  80  is substantially aligned with one of the x-axis and the y-axis (see  FIGS. 5 and 7 ) of the neck  40 ,  40   a . In this way, when a user positions the brush head  30  against his or her gums, the user is able to tactily determine whether the device  10  is oriented in a direction that will present a greater or lesser bending stiffness in response to the application of pressure against the user&#39;s gums. Thus, using the neck configuration  40  of  FIG. 5  as an example, if gentle cleaning is desired, the user can orient the device such that the y-axis is substantially parallel with the gum line. When the brush head  30  is pressed against the gum line in the direction of the x-axis, the neck  40  will relatively easily bend about the y-axis, thereby providing a soft, gentle cleaning. In contrast, if a more robust cleaning is desired, the user can orient the device such that the x-axis is substantially parallel with the gum line. When the brush head  30  is pressed against the gum line in the direction of the y-axis, the neck  40  will present greater resistance to bending, thereby provide a more vigorous, aggressive cleaning. The user can thereafter continue cleaning interdental spaces, orienting and reorienting the device as desired to provide a more gentle or more robust cleaning depending upon, for example, the sensitivity of the gum tissue in various locations of the mouth.