Toothbrush

Abstract: A toothbrush (10) comprising a head (12) having a flat surface (14) facing upwards, the head being joined to a handle. The tufts of bristles are arranged in two groups of rows (26, 40), each row extending transversely of the head (12). The rows of the first and second groups (26, 40) alternate with each other along the longitudinal axis (16) of the head (12). In the first group (26), the two laterally outermost tufts (30, 32) of each row tilt outwards towards their respective nearest side of the head, this tilt being about 12 degrees. The middle tuft (46) of each of the second group (40) extends substantially vertically upwards from the head (12). The laterally outermost tufts (44) of the second group (40) tilt laterally inwards towards each other by about 8 degrees. The tufts thus define three functional groups.

Description: This invention relates to a toothbrush construction, and more particularly to a toothbrush having its bristles arranged to provide effective removal of plaque from teeth by manual brushing. There are a number of known toothbrush constructions, however, none appear to exhibit a tuft arrangement which performs several tooth and gumline cleaning functions regardless of the style or technique employed for brushing. While a number of toothbrush manufacturers print specific brushing techniques on their brush containers, if a purchaser does not pay attention to them, or forgets them, then less than optimum teeth cleaning results. EP-A-0221000 discloses a toothbrush for a special use namely for teeth controlled by orthodontic braces. It has a line of central bristles perpendicular to the head and bristles located on either side and near the centre and tilted outwardly and bristles located near the edges of the head and tilted inwardly. The bristles are not arranged in rows transverse to the head. The relationship of the tilted bristles to the perpendicular bristles appears to be random. US-A-2168984 shows only a single central perpendicular bristle 6, then a pair of perpendicular bristles 4 along the head towards the handle, then a pair of inwardly inclined bristles 3, then four bristles 2,5,5,2, the outer two 2,2 being perpendicular and the inner bristles 5,5 being inclined outwardly. The rows (4,4),(3,3) and (2,5,5,2) then repeat and the head ends with a row (4,4). Swiss Patent CH-A-324623 has two bristles inclined to the same side at the tip and then alternating rows of three bristles, all the bristles in one row being inclined to the same side and the inclination alternating from row to row. It is an object of the present invention to provide a toothbrush which can effectively remove plaque from teeth and which is not sensitive to the brushing technique employed. According to the present invention, there is provided a toothbrush head having a centre longitudinal axis and terminating in a free end, the head having a generally flat surface from which tufts of bristles extend generally upwardly, characterised in that the tufts are arranged in two groups of rows parallel to each other and spaced axially along the longitudinal axis, each row being transverse to the longitudinal axis, the tufts in the rows of the first group comprising at least two tufts on the right hand side of the longitudinal axis which tilt towards the right and away from the longitudinal axis and at least two tufts on the left hand side of the longitudinal axis which tilt towards the left and away from the longitudinal axis; the tufts in the rows of the second group of tufts including at least one middle tuft located on the longitudinal axis and which is substantially perpendicular to the head surface, and two laterally outermost tufts each on respective opposite sides of the longitudinal axis, each said laterally outermost tuft of the second group being inclined laterally inwards towards the longitudinal axis, the rows of the first and second groups of tufts alternating in the axial direction along the longitudinal axis of the head. All of the tufts are generously spaced so as to allow independent and uninhibited movement of each tuft of bristles. The densely spaced bristle tuft configuration of conventional brush heads tend to move tangentially, push each other along and crowd each other out of inter-proximal spaces as they skid across tooth surfaces. Laterally positioned tufts are angled inwards and outwards from the centerline of the brush head so as to create a series of uniform lines of bristle tips across the length of the brush head. Half of the angled tufts are tilted laterally outward so that they project into the gingival marginal area at the base of the crowns of the teeth. Preferably, half of the angled tufts are tilted laterally inwards so that they may project into embrasures and inter-proximal spaces between the teeth. This action occurs as downward force is applied to the brush head and is not dependent upon a non-perpendicular orientation of the brush head relative to the tooth surfaces. The tufts are orientated at multi-directional angles so that they are unable to support one another structurally as downward and horizontal force is applied to them by the user. Conventional, perpendicularly orientated bristle tufts tend to act as a series of columns and thus support suspended bristles as they pass over embrasures. The minimised overall compression strength afforded by this multi-directional angled configuration allows individual tufts of bristles to penetrate embrasures and inter-proximal spaces without being inhibited from doing so by surrounding bristle tufts. Tufts are orientated at multi-directional angles so that they move in the direction of their angle. As downward and horizontal force is applied to the brush head, tufts of bristles will skid across tooth surfaces in the direction dictated by the angle in which they are anchored to the brush head rather than simply curling back in the opposite direction to that in which they are pushed. The present invention integrates multi-directional motion of bristles during unidirectional actuation of the brush. When forced into the direction of their angle, bristles will spring out of crevasses as stresses are exceeded to contain them in place. This dynamic action will tend to fling plaque out of inter-proximal spaces. Conventional devices tend to pack plaque into spaces as bristle tufts sweep over embrasures. The weak flexure strength of generously spaced angled bristle tufts of this invention allows for the reduction of bristle height without causing the sensation of increased bristle stiffness. Conventional brushes trimmed to the shorter height are perceptibly stiffer and tend to cause trauma to the mucosa. This minimised bristle height allows for greater clearance (and thus enhances reach to the rear molars) between the buccal surfaces of the teeth and the mucosal lining. Angled tufts of bristles will assume varying heights as they are deformed, yet will appear uniform in height when not in use. Angled bristles will project above the tips of straight bristles as they are forced into a perpendicular orientation during use. This effect, caused by the greater length of the hypotenuse of a triangle, allows for the angled tufts to reach deeply into interproximal and gingival marginal areas as a perpendicular orientation is assumed. According to another aspect of the invention, there is provided a toothbrush head having a longitudinal axis and terminating in a free end, the head having a surface from which tufts of bristles extend generally upwardly, characterised in that the tufts define: (a) surface bristle tufts for cleaning the broad surfaces of the teeth, the surface bristle tufts arranged in longitudinally spaced rows with the tufts of one such row tilted inwardly and the tufts of adjacent rows tilted outwardly; (b) interproximal bristle tufts arranged in a row parallel to the head longitudinal axis, these tufts being perpendicular to the head surface; and (c) gumline bristle tufts arranged in longitudinally spaced rows and tilting laterally outwardly. The invention may be carried into practice in various ways and one embodiment will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 is a partial perspective view of the head of a toothbrush formed in accordance with this invention; and Figures 2 to 4 are plan views of the toothbrush of Figure 1 and illustrate, with respective Figures 2a and 4a, the function of the several groups of tufts during their contact with the teeth and gums. Referring to Figure 1, the toothbrush 10 includes a head 12 having an upper flat surface 14. The head 12 is generally rectangular and integrally joined to a handle 20, only a part of which is illustrated. The handle may be of conventional shape and forms no part of this invention. Typically, the head 12 and handle 20 are integrally formed from a plastics material. Reference numeral 16 denotes the longitudinal axis of the head and may or may not coincide with the longitudinal axis of handle 20, although it is shown as coincident. The tufts of bristles are arranged in transverse rows 26 and 40. The rows 26 each include two pairs of laterally outermost tufts of bristles 30 and 32; these tufts are inclined laterally outwardly towards the nearest side of head 12. The tufts 30 and 32 lie in a single plane, this being the plane which contains the row 26. Preferably, tufts 30 and 32 have a lateral angle of inclination of about 12 degrees to the vertical. Corresponding or homologous tufts in the remaining rows 26 tilt in the same manner. The rows 40 include tufts 44, 46 and 44 which lie in a single plane. The middle tufts 46 are each substantially perpendicular to the head surface 14 while the outer tufts 44 are inclined upwardly towards the centre of the head 12 by about 8 degrees to the vertical. The rows 26 and 40 alternate along the longitudinal axis 16 of the head 12. A row 40 is nearest to the free end of the head farthest from the handle, as shown in Figure 1. The two kinds of groups of tuft rows are each arranged on the head 12 such that a plane, which contains the axis 16 and which is at right angles to the surface 14 and which longitudinally bisects the head 12, also bisects the middle tufts 46. Such a plane would not, however, intersect any tuft in the rows 26. All the tufts of all of the rows are of substantially the same height. In a typical construction, the vertical height of the tufts is about 10mm (0.375 inches) with the longitudinal spacing at the bottom of the tufts, between the rows 26 and 40 being about 2.3 mm (0.09 inches). The lateral spacing between tufts 30 and 32 is about 2.3mm (0.09 inches) and between tufts 46 and 32 is about 1.4 mm (0.057 inches). The lateral spacing between tufts 46 and 44 along any row 26 is about 3.4 mm (0.135 inches). The base diameter of all tufts is about 1.3 mm (0.050 inches). In Figures 2 to 4 and their respective counterparts 2a to 4a, the specific cleaning functions of the tufts are illustrated. The several functional groups of the tufts are highlighted by vertical hatching in Figures 2 to 4. In the following description, the tufts are described and grouped as to the functions they perform, while the previous description has described the tufts in terms of the transverse rows they define. In Figures 2 and 2a, the surface bristle tufts 32 and 44 clean the broad surfaces of the teeth with sets of generously spaced, oppositely acting and oppositely angled bristle tufts. As downward force and horizontal motion is applied to the brush head, the surface bristle tips sweep along tooth surfaces in the direction of their angle rather than simply curl back in the opposite direction to that in which they are pushed. This dynamic action allows multidirectional motion of bristle tips during uni-directional actuation of the brush. Tufts of bristles are oriented at multidirectional angles so that they are unable to support one another as downward and horizontal force is applied to them by the user. The densely spaced, straight bristle tuft configuration of conventional brush heads tends to move tangentially and curl in the opposite direction to that in which they are pushed. As bristles curl away from the direction of the motion, fewer bristle tips come into direct contact with tooth surfaces. The tufts 44 of any row 40 tilt towards each other while the tufts 32 of any adjacent row 26 tilts laterally outwards. In Figures 3 and 3a, as the surrounding (non-highlighted) angled tufts of bristles yield to downward force, straight interproximal bristle tufts 46 deeply penetrate embrasures and interproximal spaces. These bristle tufts are arranged in a row along the axis 16, with each tuft being perpendicular to the head surface. Conventional, perpendicularly oriented bristle tufts tend to act as a series of columns and thus support suspended bristles as they pass over embrasures. The combined compression strength of conventional straight bristle tufts inhibits individual tufts of bristles from penetrating interproximal spaces. In Figures 4 and 4a, perimeter bristle tufts 30 are tilted laterally outwards along the sides of the head 12 so that upon brushing they project towards the gingival marginal area at the base of the crowns of the teeth. As downward force is applied to the brush head, the angled bristle tufts 30 tend to reach into the gingival margin as they move in the direction of their angle. The tufts 30 defined two parallel rows along the sides of the head. Conventional straight tufted brushes require the user to orient the brush head at a 45 degree angle in order to access the gingival marginal area. When a conventional brush is orientated to optimise gingival marginal cleaning, other areas of the teeth are less effectively accessed. There are thus three functional groups of bristle tufts in head 12 defined by the two types of rows 26 and 40. The rows 26 and 40 have been described as being transverse to the axis 16 with each of rows 26, 40 being identical. This arrangement yields the maximum cleaning action regardless of brushing technique.

Claims: A tooth brush head (12) having a central longitudinal axis (16) and terminating in a free end, the head (12) having a generally flat surface (14) from which tufts of bristles extend generally upwardly, characterised in that the tufts are arranged in two groups of rows (26,40) parallel to each other and spaced axially along the longitudinal axis (16), each row being transverse to the longitudinal axis (16); the tufts in the rows of the first group (26) comprising at least two tufts (30,32) on the right hand side of the longitudinal axis (16) which tilt towards the right and away from the longitudinal axis (16) and at least two tufts (30,32) on the left hand side of the longitudinal axis (16) which tilt towards the left and away from the longitudinal axis (16); the tufts (44,46) in the rows of the second group (40) of tufts including at least one middle tuft (46) located on the longitudinal axis (16) and which is substantially perpendicular to the head surface (14), and two laterally outermost tufts (44) each on respective opposite sides of the longitudinal axis (16), each said laterally outermost tuft (44) of the second group being inclined laterally inwards towards the longitudinal axis (16), the rows of the first and second groups (26,40) of tufts alternating in the axial direction along the longitudinal axis (16) of the head (12). A toothbrush head as claimed in claim 1, characterised in that the second group of tufts (40) comprises single rows of three tufts, the middle tufts (44) being substantially at right angles to the head surface (14). A toothbrush head as claimed in claim 1 or claim 2, characterised in that each row of the first group of tufts (26) comprises four tufts, the pair of tufts (30) on each side of axis (16) in each row tilting in the same respective direction. A toothbrush as claimed in any preceding claim, characterised in that the laterally outermost tufts (44) of the second group of tufts tilt laterally inwards at an angle of about 8 degrees to the vertical. A toothbrush as claimed in any preceding claim, characterised in that the angle of inclination of the tufts (30,32) of the first group is about 12 degrees to the vertical. A toothbrush as claimed in any preceding claim, characterised in that a row of the second group of tufts (40) is positioned nearest the head free end. A toothbrush as claimed in any preceding claim, characterised in that the tufts of all of the rows are of substantially the same height when measured vertically.

Inventors: CRAWFORD JOHN C, CURTIS JOHN P, EDELMAN LAURA H, HEINZELMAN BERT D, KEMP JAMES H, LAMOND DONALD R, MINTEL THOMAS E, RUSTOGI KEDAR N, CRAWFORD, JOHN C., CURTIS, JOHN P., EDELMAN, LAURA H., HEINZELMAN, BERT D., KEMP, JAMES H., LAMOND, DONALD R., MINTEL, THOMAS E., RUSTOGI, KEDAR N.
Applicants: COLGATE PALMOLIVE CO, COLGATE-PALMOLIVE COMPANY
Application year: 1991
Main classification: A46B9
IPC codes: A46B9