Patent Publication Number: US-6990706-B2

Title: Toothbrush

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to dental cleaning implements, especially in particular to toothbrushes having a resiliently flexible region in their structure, particularly having such a structure situated in their handle or between their head and their handle. 
   Toothbrushes generally comprise a head carrying a dental cleaning tool, normally a cluster of bristles in a toothbrush, and a grip handle, arranged along a longitudinal head-handle axis. Often there is a thinned neck region between the head and the part of the handle which is gripped by the user during use. It is known to incorporate a resiliently flexible region in the handle or between the head and the handle to help to relieve excessive pressure from being applied to the teeth or other mouth tissues of the user during implementing. Examples of such resiliently flexible regions in toothbrushes are disclosed in EP 0 0336 641A and DE 39 234 95. 
   Different users of toothbrushes may prefer or need toothbrushes having different degrees of resilient flexibility of such a region. At present the user has no option except to purchase a complete different implement having a selected degree of flexibility of such a region. WO 95/10959 discloses a toothbrush having a modification of a two-part slideable finger grip to reinforce and alter the flexibility of the handle section as required by the user. U.S. Pat. No. 5,315,732 discloses a toothbrush having a flexible part between its head and handle in the form of two parallel flexible springs between which a rigid piston may be driven by the user to adjust the flexibility. 
   BRIEF SUMMARY OF THE INVENTION 
   It is an object of this invention to provide a dental cleaning implement particularly a toothbrush having a resiliently flexible region in its structure wherein the resilience and/or flexibility of the region may be altered by the user. 
   According to this invention a dental cleaning implement has a head which carries a dental cleaning tool, and a grip handle, the head and handle being along a longitudinal head-handle direction, the implement has a resiliently flexible structure situated in its handle or between its head and its handle, which can resiliently bend under the action of pressure experienced by the head during toothbrushing, and the implement has adjustment means by which the user may alter the flexibility of the structure between less and more flexible, the adjustment means comprising a longitudinally moveable stiffening member which can be moved longitudinally into greater or lesser engagement with the resiliently flexible structure. 
   The dental cleaning implement may preferably be a toothbrush having a dental cleaning tool which comprises a cluster of bristles projecting from the head in the manner of a conventional toothbrush, or alternatively may comprise a dental flossing tool. 
   DETAILED DESCRIPTION OF INVENTION 
   By “lesser engagement” herein is included the possibility that the stiffening member is not engaged at all with the structure, such that movement into “greater engagement” can include the possibility that the stiffening member moves from a position of non-engagement to a position in which it is wholly or partly engaged with the structure. 
   By “flexible” herein is meant primarily displacing in a direction perpendicular to the longitudinal axis under the action of pressure applied to the head in a direction perpendicular to the longitudinal axis. By “less flexible” herein is meant primarily that for a unit of pressure the structure displaces less than a “more flexible” structure, or that more pressure is required to cause a unit of displacement than is required for a “more flexible” structure. The principal mode of displacement of such a flexible structure is a bending of the flexible structure. 
   By “resilient” herein is meant primarily that upon release of the above-mentioned pressure the resilient structure returns rapidly back to the position it had before the pressure was applied, in the manner of a spring. 
   The combination of the flexible structure and the stiffening member when the stiffening member is more engaged with the structure is less flexible than the combination when the stiffening member is less engaged with the flexible structure, for example when the stiffening member is not engaged at all with the flexible structure. 
   In one embodiment the stiffening member may be mounted externally on the flexible structure, or on the handle, or on the neck of the toothbrush longitudinally adjacent to the flexible structure, particularly on the handle between the flexible structure and the end of the handle longitudinally remote from the head. Such an externally mounted stiffening member may move along the external surface of the toothbrush. 
   For example the flexible structure, and preferably the handle of the toothbrush, particularly a part of the handle longitudinally adjacent to the flexible part, may have one or more guide with which the stiffening member may engage and which can guide the stiffening member in its longitudinal movement. Such a guide may comprise a longitudinal groove, ledge, or rail etc in the external surface of the flexible structure and/or handle. Additionally or alternatively the flexible structure and/or handle may have one or more internal guide, e.g. a longitudinally extending slot, with which the stiffening member can engage. 
   The stiffening member may have one or more part which can engage with the one or more guide and which can ride longitudinally along the one or more guide. The stiffening member may be moveable longitudinally along the guide into greater or lesser engagement with the resiliently flexible structure. 
   For example the stiffening member may wholly or partly surround the flexible structure or the handle or neck of the toothbrush adjacent to the flexible structure in the manner of a whole or partial sleeve or “saddle” which is moveable on the flexible structure, handle or neck. 
   The stiffening member may for example comprise one or more longitudinally extending arm, e.g. extending in the direction toward the head of the toothbrush, which can engage with the flexible structure. 
   In another embodiment the stiffening member may be moveable internally within the flexible structure. For example the flexible structure may have a longitudinally extending internal channel along which the stiffening member may move within the structure. This channel may continue into, or connect with another channel in, the adjacent part of the handle or neck of the toothbrush. 
   The stiffening member is provided with means to enable it to be moved longitudinally into greater or lesser engagement with the resiliently flexible structure. 
   In one embodiment the stiffening member may be longitudinally slideable in relation to the flexible structure. The stiffening member may be retained moveably, e.g. slideably on the toothbrush by for example a snap fit engagement with the handle, neck or flexible structure. For example there may be a longitudinally slideable stiffening member on each side of the toothbrush, these members being linked together to enable them to move together slideably along the toothbrush. For example there may be a link between these members and a longitudinal guide slot passing through the toothbrush and along which this guide may run. 
   In another embodiment the stiffening member may be longitudinally moveable by a whole or partial screw thread type action e.g. by a rotatable part having such a thread operating upon a thread on the stiffening member. Alternative means for making the stiffening member longitudinally moveable will be apparent to those skilled in the art. 
   For example when the stiffening member is mounted externally on the toothbrush the user may easily move it by a hand or finger action. When the stiffening member is moveable internally it may be necessary to expose part of the stiffening member outside of the channel, or provide it with an externally extending handle which enables the user to move it longitudinally. Alternatively an internal stiffening member may be provided with a driver, e.g. with a screw thread means which can be rotated to screw the stiffening member longitudinally along the toothbrush. 
   In one embodiment the flexible structure may comprise a region of “U” or “V” shaped folds in the material of the toothbrush, two longitudinally adjacent back-to-back “U” or “V” folds forming respectively an “S” or “Z” shaped folded region. Such a structure is for example disclosed in EP 0 336 641A. Each of such folds typically comprises a pair of limbs which meet to define the “U” or “V” shape, with a fold axis at the meeting of the limbs and extending in projection out of the plane in which the “U” or “V” shape lies. Such a flexible region may taper in 
   Another flexible structure comprises a composite region of one or more relatively more flexible elastomer parts and one or more relatively less flexible plastic material parts such that the structure may for example be constructed more or less flexible by an appropriate selection of plastic and elastomer materials and parts. 
   An example of such a composite flexible structure comprises a region of “U” or “V” shaped folds in the material of the toothbrush, two longitudinally adjacent back-to-back “U” or “V” folds forming respectively an “S” or “Z” shaped folded region as described above, with an elastomer material in the concavity or “bite” between the limbs of the folds. In such a construction the elastomer material between the folds may be compressed as the composite flexible structure bends and the limbs move toward each other. The elastomer material thereby resists the bending deformation of the flexible structure and the presence and amount of the elastomer material can be used to control the flexibility. The folds may be additionally linked by linking structures of the plastic material of the toothbrush, for example one or more integral longitudinal linking rib between the limbs of the folds. 
   Other kinds of flexible structures comprise thin regions of plastic material in the handle or between the head and the handle such as a thin, longitudinally extending, plastic material neck between the head and the handle. For example such a structure may be tubular having the above-described internal conduit. 
   Suitably the flexible structure may be preferentially flexible in certain directions. For example if the dental cleaning tool comprises a cluster of bristles extending generally in a bristle direction perpendicular to the longitudinal axis the flexible structure may be preferentially flexible in the plane which includes the longitudinal axis and the bristle direction. 
   In a preferred embodiment, the resiliently flexible structure is a region of “U” shaped folds, such that pairs of longitudinally adjacent “U” shaped folds thereby form an “S” shaped fold, the fold axes of the folds being aligned perpendicular or at an acute angle to the longitudinal axis and to the bristle direction; preferably there is an elastomer material in the bite between the limbs of the folds; situated on the handle of the toothbrush is a longitudinally moveable slider; the flexible structure has one or more external guide, e.g. one or more longitudinally extending groove on each side; the stiffening member comprises one or more arm, preferably one on each side of the toothbrush, which extend longitudinally toward the toothbrush head when the slider is on the handle, and the one or more arm engages with the one or more guide when the slider is moved longitudinally toward the head. 
   The stiffening member in this last described embodiment is preferably moveable longitudinally between two extreme longitudinally displaced positions. In a first extreme position the slider is distanced from the head, in which position the stiffening member, e.g. the one or more arm, is not engaged or only engaged to a small extent with the flexible structure. In the second extreme position the slider is closer to the head, in which position the one or more arm engages more fully with the structure. In the second position the combination of the flexible structure engaged with the one or more arm is less flexible than the flexible structure without the one or more arm engaged. 
   For example in this embodiment progressive movement of the one or more arm toward the toothbrush head may cause the one or more arm to cross a progressively greater number of limbs of the “U” or “V” shaped fold, and to bridge a progressively greater number of the “bites” between adjacent limbs. 
   In another preferred embodiment the flexible structure may be a region of “U” shaped folds as above and is a hollow tubular structure, having an internal longitudinally extending internal channel, situated within which is an internal longitudinally moveable stiffening member, which has a part which can engage with and move longitudinally internally along the channel inside the flexible structure. The stiffening member may be moved within the channel between two extreme longitudinally displaced positions, at which the stiffening member is respectively to a lesser extent engaged with the flexible structure, and to a greater extent engaged with the flexible structure. As the stiffness of the structure is greater with the part more fully engaged than with the part less fully engaged with the flexible structure these extreme positions of the stiffening member provide more and less stiff states of the toothbrush. 
   The flexible structure, the stiffening member and other parts of the toothbrush of the present invention may be made of plastics and elastomer materials conventional in the art of toothbrush manufacture, as may other parts of the toothbrush such as the head, grip handle and the dental cleansing implement such as a cluster of nylon bristles or a dental flossing tool. The head may be replaceably attachable to the toothbrush handle. 
   The dental cleaning implement of the present invention may be made using conventional injection moulding technology and processes. 
   Accordingly in a further aspect the present invention provides an injection moulding process in which a dental cleaning implement and its component parts may be made. Further the present invention provides a mould or set of moulds in which the dental cleaning implement of the present invention or its component parts may be made. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a toothbrush with a slider in one extreme position. 
       FIG. 2  is a top view of the toothbrush in  FIG. 1 . 
       FIG. 3  is a side view of the toothbrush with a slider in other extreme position. 
       FIG. 4  is a top view of the toothbrush in  FIG. 3 . 
       FIG. 5  is a side view of the toothbrush with slider in an intermediate position. 
       FIG. 6  is a top view of the toothbrush in  FIG. 5 . 
       FIG. 7  is a top and side view of slider. 
       FIG. 8  is a cross-section of the toothbrush in  FIG. 1  at D—D. 
       FIG. 9  is a cross-section of the toothbrush in  FIG. 3  at E—E. 
       FIG. 10  is a top view of a second embodiment of a toothbrush with a slider. 
       FIG. 11  is a side view of the toothbrush in  FIG. 10 . 
       FIG. 12  is a broken down view of all the parts in  FIG. 10 . 
       FIG. 13  is a partial cross-sectional view of a third embodiment of a toothbrush with a stiffening member. 
       FIG. 14  is the stiffening member of  FIG. 13 . 
       FIG. 15  is an enlarged side view of part of another flexible structure. 
       FIG. 16  is a cross-section of the toothbrush in  FIG. 15  at F—F. 
       FIG. 17  is a side view of part of another flexible structure. 
       FIG. 18  is a cross-section of the toothbrush in  FIG. 17  at G—G. 
   

   The invention will now be described by way of example only with reference to the accompanying drawings  FIGS. 1–18  which show part cutaway and part sectioned views of toothbrushes of the present invention. 
   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1 to 9  a toothbrush is shown  10  (overall) comprising a head  11 , which carries a cluster of bristles  12  projecting from head  11  in a bristle direction B, a grip handle  13  and a thinned neck part  14 , all being disposed along a longitudinal direction A—A. Located longitudinally between the head  11  and the grip handle  13  is a resiliently flexible structure  15  being a region of “U” shaped folds  16  of the plastics material of which the toothbrush is made, the fold axes C—C of the folds being aligned perpendicular to the longitudinal axis A—A and to the bristle direction B. In  FIGS. 1 ,  3 , and  5  the “U” shape of the folds  16  can be seen, each of the folds comprising a pair of limbs  16 A,  16 B which meet at  16 C to define the “U” shape in the plane of the drawing, with the projected fold axis C—C extending out of the plane of the drawing. Pairs of longitudinally adjacent “U” shaped folds thereby form an “S” shaped fold. 
   Situated on the handle  13  is a longitudinally moveable stiffening member  17  being a slider  18 , shown more clearly in side and top views in  FIG. 7 , which is a part sleeve generally “C” shaped in cross section about the longitudinal direction A—A as shown more clearly in  FIG. 8 , which is a cross section at D—D in  FIG. 1 . The toothbrush handle  13  is provided externally with longitudinally extending guide ledges  19 . The slider  18  can snap over the toothbrush grip handle  13  and be retained thereon by its resilience, and by the engagement of grip portions  110  of the slider  18  with the ledges  19 . 
   The structure  15  has external longitudinally extending guide grooves  111  on each of its sides. The slider  18  has two arms  112  which extend longitudinally toward the toothbrush head  11  when the slider  18  is retained on the handle  13 , and the arms  112  engage with the guide grooves  111  in the structure  15  when the slider  18  is in position retained on the handle  13 , as shown in cross section in  FIG. 9 , which is a cross sectional view through the flexible region  15  at line E—E in  FIG. 3  looking in the direction of the arrows. 
   The slider  18  is moveable longitudinally between two extreme longitudinally displaced positions. In one extreme position shown in  FIGS. 1 and 2  the slider  18  is as distanced from the head  11  as it can be whilst retained on the handle  18 . The handle  18  is provided with end-stop abutment surfaces, not shown, against which the slider  18  abuts when it is in this position and so that the slider  18  cannot move any further away from the head  11  or fall off the handle. In this position the arms  112  are only engaged to a small extent with the flexible structure  15 , i.e. only extending via groove  111  across the “U” fold  16  which is closest to the handle  13 . 
   In the other extreme position shown in  FIGS. 3 and 4  the slider  18  is as close to the head  11  as it can be whilst retained on the handle  13 . In this position the arms  112  engage more fully with the structure  15 , i.e. extending as far as the “U” fold  16  closest to the head  11 . The toothbrush handle  13  may be provided with end-stop abutment surfaces (not shown) to prevent the slider  18  from moving closer to the head  11 . 
   A situation with the slider in an intermediate position is shown in  FIGS. 5 and 6 , where the arms  112  engage with the structure  15  as far as the longitudinal centre of the structure  15 . 
   As the combination of the structure  15  with the arms  112  engaged with the grooves  111  is less flexible than the structure  15  without the engaged arms  112 , the situation shown in  FIGS. 1 and 2  is a less stiff structure, the situation shown in  FIGS. 3 and 4  is a more stiff structure, and the situation shown in  FIGS. 5 and 6  is a structure of intermediate stiffness. In the constructions shown in  FIGS. 1–9 , stiffness is determined as the resistance to bending under the influence of pressure applied to the head  11  in the direction of the arrow shown. 
   The slider  18  may be moved by the thumb of the user whilst holding the handle  13 , and the slider may be provided with a window  113  which is open to differently indicated, e.g. differently coloured regions  114  on the handle  13  to give the user a visual indication of the position of the slider  18  which has been selected and of the consequent stiffness of the toothbrush. 
   Between the limbs of the folds  16  in the flexible region  15  of  FIGS. 1–9  is a longitudinal strengthening rib  115  which is integral with the folds  15 . The dimensions of the rib  115  can be selected to control the inherent flexibility of the region  15 . 
   Referring to  FIGS. 10 ,  11  and  12  a toothbrush is shown overall  20  which comprises a head  21 , which carries a cluster of bristles  22  projecting from head  21  in a bristle direction B, a grip handle  23  and a thinned neck part  24 , all being disposed along a longitudinal direction A—A. located longitudinally between the head  21  and the grip handle  23  is a resiliently flexible structure  25  being a region of “U” shaped folds  26  of the plastics material of which the toothbrush is made, the fold axes C—C of the folds being aligned perpendicular to the longitudinal direction A—A and to the bristle direction B. Pairs of longitudinally adjacent “U” shaped folds thereby form an “S” shaped fold. 
   The structure  25  is a hollow tubular structure, having an internal longitudinally extending internal channel  27 . Situated within the channel  27  is an internal longitudinally moveable slider  28 . The slider  28  can engage with and move longitudinally internally along the flexible part  25  and has a handling button  29 . The channel  27  extends into the handle at  210 . The part  210  has a window  211  by which the user may move the slider  28  longitudinally within channel  27  using button  29  which is exposed through window  211  and through which the user can see the position of the slider  28 . 
   The slider  28  may be moved within channel  27  between extreme longitudinally displaced positions. As shown in  FIGS. 10 and 11 , the slider  28  is at a position in which the part  29  is to a greater extent engaged within the structure  25  i.e. extending internally within structure  25  as far as the closest of the “U” folds  26  to the head  21 . It will be apparent that by moving the slider  28  to the right of the position shown in  FIGS. 10 and 11  the slider  28  becomes to a lesser extent engaged with the structure  25 . The extent to which the part  29  is engaged with the structure  25  is visually indicated by the position of the part  210  in the window  211 . As the stiffness (as defined with reference to  FIG. 1 ) of the structure  25  is greater with the part  29  more fully engaged with the structure  25  than with the part  29  less fully engaged with the part  25 , the extreme positions of the slider  28  represent more and less stiff states of the toothbrush  21 . 
   In  FIG. 12  a possible construction of the toothbrush shown in  FIG. 10  is shown, in which the handle  23 , and the integral combination of the head  21 , neck  24  and flexible structure  25  are made separately, the slider  28  introduced and the toothbrush assembled. An elastomer washer  212  may be fitted between the assembled parts. 
   Referring to  FIGS. 13 and 14  a toothbrush is shown overall  30  which comprises a head  31 , which carries a cluster of bristles (not shown) projecting from head  31 , a grip handle  32  and a thinned neck part  33 , all being disposed along a longitudinal axis direction A—A. Located longitudinally between the head  31  and the grip handle  32  is a resiliently flexible structure  34  being a region of “U” shaped folds  35  of the plastics material of which the toothbrush is made, the fold axes C—C of the folds being aligned perpendicular to the longitudinal axis A—A and to the bristle direction B. Pairs of longitudinally adjacent “U” shaped folds thereby form an “S” shaped fold. 
   The structure  34  is again a hollow tubular structure, having an internal longitudinally extending channel  36 . In the structure shown in  FIG. 13  the channel  36  extends as shown  37  to continue internally along the entire length of the handle  32 . Situated internally within channel  36  is a longitudinally moveable stiffening member  38 , the shape of which is shown more clearly in  FIG. 14 . At the end  39  of the handle  32  the stiffening member  38  terminates in a part  310  external to the handle  32  when the stiffening member  38  is within channel  36 . The part  310  has a screw threaded external surface and is enclosed within a cap  311  which is rotatably mounted on handle  32  at end  309 , and which includes an internal screw thread  312  which engages with the screw thread part  310 . When the cap  311  is rotated on handle  32  the engagement of the screw thread  312  and part  310  causes the stiffening member  38  to be moved longitudinally along inside channel  36 , the direction of longitudinal movement depending upon the direction of rotation of the cap  311 . 
   In a manner analogous to that shown in and described with reference to  FIGS. 10–12  the longitudinal movement of the stiffening member  38  within flexible structure  34 , into greater (further to the left) and lesser (further to the right) engagement with the structure  34  allows the flexibility of the toothbrush  31  to be varied between more and less stiff states. Instead of the part  310  and rotatable cap  311  the stiffening member  38  may be provided with a push button (not shown) externally of the end  309  by means of which the stiffening member  38  may be pushed longitudinally along inside the channel  36 . 
   Referring to  FIGS. 15 and 16  an enlarged side view of part of another flexible structure  41  (overall) of a toothbrush of this invention is shown.  FIG. 16  is a cross section of  FIG. 15  through line F—F. The flexible structure  41  is situated between the neck  42  and grip handle  43  of the toothbrush. The flexible structure  41  comprises a region of “V” shaped folds  44 , similar to that shown in  FIGS. 1–9 , formed by longitudinally adjacent pairs of limbs  44 A and  44 B which meet at  44 C, each aligned at an acute angle to the longitudinal direction A—A and to define an acute angled “V” shape between them with a fold axis C—C extending perpendicularly out of the plane of the drawing of  FIG. 15 . The folds  44  are longitudinally linked by an integral longitudinal rib  45 . In the concavity or “bite” between the limbs  44 A and  44 B, and between the handle  43  and the limb nearest the handle, and between the neck  42  and the limb nearest the neck  42 , is an elastomer material  46 . As the region  41  bends under pressure experienced by the head of the toothbrush during toothbrushing the limbs  44 A,  44 B will compress the elastomer material  46  between them, and the elastomer material will thereby resiliently resist the bending of the region  41 . 
   The limbs  44 A,  44 B and the elastomer material  46  have a longitudinal guide groove  47  on both sides of the region  41 . A slider  48 , similar in construction to that  17  shown in  FIGS. 1–9  is slideably mounted on the handle  43 , and has two arms  49  which are stiffening members which can engage with the flexible region  41  as the arms  49  are longitudinally moved along the grooves  47  in a manner analogous to that described with reference to  FIGS. 1–9 . End stop abutment surfaces  410  are present on the toothbrush handle  43  to limit the longitudinal movement of the slider  48  toward the head, and there are similar end-stop surfaces toward the other end of the toothbrush handle  43 . The arms  49  can engage with the flexible region  41  to greater or lesser extents to adjust the flexibility in a manner analogous to  FIGS. 1–9 . The flexible region  41  may taper in its thickness in the bristle direction, becoming thinner closer to the head. 
   Referring to  FIG. 17  a side view of part of another flexible structure  51  (overall) of a toothbrush of this invention is shown. The flexible structure  51  is situated between the neck  52  and grip handle  53  of the toothbrush. The flexible structure  51  comprises a region of “V” shaped folds  54 , similar to that shown in  FIGS. 1–9 , formed by longitudinally adjacent pairs of limbs  54 A and  54 B which meet at  54 C, each aligned at an acute angle to the longitudinal direction A—A to define an acute angled “V” shape between them with a fold axis C—C extending perpendicularly out of the plane of the drawing of  FIG. 17 . In the concavity or “bite” between the limbs  54 A and  54 B, and between the handle  53  and the limb of the fold  54  nearest the handle  53 , and between the neck  52  and the limb  54  nearest the neck  52 , is an elastomer material  55 . As the region  51  bends under pressure experienced by the head of the toothbrush during toothbrushing the limbs  54 A,  54 B will compress the elastomer material  55  between them, and the elastomer material  55  will thereby resiliently resist the bending of the region  51 . 
   The limbs  54 A,  54 B and the elastomer material  55  have a longitudinal guide groove  56  on both sides of the region  51 , and which extends into the handle  53 . A slider  57  is slideably mounted on each side of the toothbrush. Each slider  57  comprises a longitudinally extending arm which can engage with the flexible region  51  as it is moved longitudinally moved along the grooves  56  in a manner analogous to that described with reference to  FIGS. 1–9 . As the slider  57  moves toward the head of the toothbrush it engages the region  51  and progressively crosses a greater number of the limbs  54 A,  54 B and bridges a progressively greater number of “bites” between the limbs  54 A,  544 B, and the combination of the region  51  and slider  57  becomes progressively less flexible than the flexible region  51  alone. 
   An end stop abutment surface  58  limits the longitudinal movement of the slider  57  toward the head, and there are similar end-stop surfaces toward the other end of the groove  56  in the toothbrush handle  53 . 
     FIG. 18 , a cross section through the toothbrush of  FIG. 17  at line G—G shows how the two sliders  57 , one on either side of the toothbrush, are connected by a link comprising two respective snap fit plug and socket connectors  59 ,  510 , and which runs in a guide slot  511  passing through the toothbrush handle  53 . The slot  511  runs longitudinally along within the toothbrush handle to guide the movement of the sliders  57 . The sliders  57  and the link  59 ,  510  may frictionally engage with the surfaces of the toothbrush and slot  511  respectively to help to retain the sliders  57  in a selected longitudinal position. The guide grooves  56  and/or the slot  511  may have snap positions which enable the slider to snap into and be retained in a selected longitudinal position, e.g. corresponding to “soft, medium and hard”. The slider  57  and parts of the toothbrush may have position indicators on them to indicate to the user which position is selected. The slider  57  may have a roughened surface to assist the user to grip and move the slider.