Patent Publication Number: US-2023143045-A1

Title: Method of Manufacturing Bristled Pad and Mouthpiece for Brushing Plurality of Dental Positions, Mouthpiece and Bristle Pad

Description:
The invention relates to the field of dental cleaning devices having a mouthpiece for simultaneously brushing at a plurality of dental positions, in particular to dental cleaning devices wherein the mouthpiece is of the type comprising a body having a recess and at least one bristle carrier lined with bristles, wherein the recess has a J-shaped or U-shaped length direction and a U-shaped cross-section transverse to the length direction and being configured for encompassing a dental arch of multiple dental positions, and wherein the at least one bristle carrier delimits the recess. Such a dental cleaning device is used for simultaneously cleaning multiple—preferably all the—teeth and/or dental positions (in case one or more teeth may be missing) of one dental arch or both dental archs in case the body has two such recesses having the J-shaped or U-shaped length directions of both recesses extending parallel and having the U-shaped cross-sections of both recesses opening in mutually opposite direction. 
     BACKGROUND OF THE INVENTION 
     Cleaning of teeth of humans and animals is a prerequisite for oral health, and health of internal organs. Various dental cleaning devices are available, such as manual and powered toothbrushes. With these typical toothbrushes, it is advised to brush the teeth by a prescribed method for at least two minutes per day to effectively remove plaque. Yet, an average person does not spend all of the prescribed time cleaning his or her teeth, and does not always brush according to an effective method. Additionally, for disabled or elderly persons or children it can be difficult to brush the teeth with a toothbrush, since typical toothbrushes require precise positioning of the brush bristles on various surfaces of the teeth. 
     In case at some or all dental positions teeth are missing as is frequently the case with elderly persons, cleaning of the gum at these dental positions is still a prerequisite for oral health, and health of internal organs. 
     There is a need to automatically brush the teeth and/or gum at the dental positions for cleaning the teeth and/or gum at these dental positions, whereby the time and effort required for effective brushing is reduced. In addition, there is a need to avoid carefully manoeuvring the brush. 
     Dental cleaning devices are known comprising mouthpieces which cover the maxillary dental arch and/or the mandibular dental arch. These mouthpieces may be of the type comprising a body provided with at least one recess delimited by a recess wall lined with a plurality of bristles extending from the recess wall into the recess, the recess wall defining a U-shaped length axis and, viewed transverse to the length axis, a U-shaped cross-sectional shape and being configured for encompassing a plurality of dental positions along a dental arch. The dental positions, like teeth and/or gum, to be brushed are inserted in the at least one recess and the recess wall lined with bristles is operated to brush the teeth and/or gum with the bristles on the recess wall. Depending on the length of the recess several or all dental positions of the maxillary dental arch and/or the mandibular dental arch may be brushed simultaneously. An example of such a mouth piece can be found in WO-2018/199760. 
     A part of such a mouthpiece is the recess wall lined with bristles, which recess is in length direction U-shaped and has transverse to this length direction a U-shaped cross-section, and which has the bristles at the inner side of the recess. The small inner space of the U-shaped cross-section and the arch-shaped length make the manufacturing of such a recess wall lined with bristles quite difficult. Of course such a recess wall lined with bristles can be made manually by attaching the bristles or tufts of bristles one by one to the recess wall. This is however labour intensive and not time and cost efficient. Such a recess wall with U-shaped cross-section and bristles on the inner side of the recess may further be made by injection moulding the recess wall and bristles simultaneously, but, due to the small inner width of the U-shape, unloading the moulded recess wall and bristles from the mould is not possible or quite difficult to deal with without damaging the moulded product. 
     Further problems with such mouthpieces of the type according to WO-2018/199760 or according to other designs like for example shown in WO-2009/150559, U.S. Pat. Nos. 8,359,692, 4,224,710, are amongst others:
         Because the mouthpiece is to be fully inserted into the mouth the dimensions of the mouthpiece are to be kept small in order to avoid discomfort in use and gag reflex. Keeping dimensions small is the more a problem when a drive is to be arranged I the mouthpiece for bringing the bristles into a cleaning motion. The mouthpiece should fit around the teeth. All this means that it is of importance to keep the bristle connection (i.e. the attachment of the bristles to the rest of the mouthpiece) as small as possible.   On the other hand, in order to avoid bristles to separate from the mouthpiece (and possibly being swallowed by the user), it is of importance that the bristles meet a certain retention force. 15-20 Newton per tuft is presently a usual standard for the retention force. This retention force contradicts keeping the bristle connection as small as possible.   The requirements used for the bristle material frequently differ from the ones of the material used for the rest of the mouthpiece, resulting in challenges in attaching the bristles to the rest of the mouthpiece.   The bristle lining inside the recess has to be able to follow the U-shaped dental arch as well as the much smaller U-shaped cross-sectional shape of the recess.       

     Thus there is a need for a method of manufacturing a mouthpiece for simultaneously brushing at a plurality of dental positions, wherein the mouthpiece is of the type comprising a body having a recess lined with bristles, which recess has a J-shaped or U-shaped length direction and a U-shaped cross-section transverse to the length direction and is configured for encompassing a dental arch of multiple dental positions, and wherein the at least one bristle carrier delimits the recess. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an alternative method of manufacturing a mouthpiece for simultaneously brushing at a plurality of dental positions, wherein the mouthpiece is of the type comprising a body having a recess lined with bristles, which recess has a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction and is configured for encompassing a dental arch of multiple dental positions, and wherein the at least one bristle carrier delimits the recess. A further object of the invention is to provide such a method overcoming one or more of the above problems associated with the manufacturing of such mouthpieces. 
     According to a first aspect of the invention, one or more of the above objects are achieved by providing a method of manufacturing a mouthpiece for simultaneously brushing at a plurality of dental positions, the mouthpiece being of the type comprising a body defining a recess which is lined with bristles and has a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction (the cross-section may be partly U-shaped, because, for example at the incisors, the bottom of the U-shape may be open or V-shaped); 
     wherein the method comprises a pad manufacturing step in which at least one pad with bristles is made; the pad comprises a pliable foil—such as a plastic foil—and bristles—such as plastic bristles—projecting from a front surface of the foil; the foil having a back surface opposite the front surface; and the pad manufacturing step comprising:
         providing bristles with a fixed end and a free end,   providing a prefabricated foil having a thickness of at most 700 μm, and   fusing the fixed ends of the bristles with the prefabricated foil, resulting in the bristled pad to be made;       

     wherein the method further comprises a body providing step in which a body of the mouthpiece to be manufactured is provided; the body providing step comprising providing a body with a recess and at least one bristle carrier; the recess having a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction and being configured for encompassing a dental arch of multiple dental positions; the at least one bristle carrier delimiting the recess; and 
     wherein the method further comprises a pad attaching step in which during or after the body providing step one or more bristled pads obtained in the pad manufacturing step are attached to the at least one bristle carrier to line the bristle carrier with bristles; the back surface side of the foil facing the bristle carrier and the front surface side of the foil facing away from the bristle carrier into the recess. 
     The method according to the invention basically comprises three main steps. Each main step may comprise further sub-steps, some of which will be discussed further below. 
     The main steps are manufacturing a bristled pad—called the pad manufacturing step—, a body providing step in which the body is provided, and a pad attaching step wherein the bristled pad is attached to the body. According to a further embodiment of the invention, the prefabricated foil may be manufactured in the pad providing step, such as about simultaneously with fusing the bristles to the prefabricated foil. This may for example be done by extruding or injection moulding the foil over the fixed ends of the bristles, in which use is made of the foil still being in a hot condition enabling it to be fused with the fixed ends of the bristles. According to an alternative or supplementary other further embodiment of the invention, the body may be manufactured in the providing step. 
     The bristled pad may already have been made before the body providing step. The bristled pad may be attached to the body after the body providing step. In case the body is manufactured in the body providing step, the bristled pad may also be attached to the body during the body providing step. The bristled part may for example be adhered with an adhesive to the bristle carrier. Attaching the bristled pad to the body during the body providing step may according to a specific embodiment of the invention considerably facilitate integrating the pad as integral part of the body. An example of attaching the bristled pad during the body providing step, is integrating the pad into the body during injection moulding the body or part of the body. The pad may be a pre-fabricated insert and may be placed in the mould before injecting the injection moulding material for moulding (at least part of) the body so that after hardening of the injection moulding material the pad is integrated with or in the injection moulding material. The bristled pad may also be made during, such as simultaneously with, or after the body providing step. When the bristled pad is made after the body providing step, the pad attaching step will take place after the body providing step as well. In this case the pad attaching step may be a step in which two pre-fabricated parts (the bristled pad and the body or part of the body) are assembled together. As will be clear to the skilled man, it is also conceivable that the pad attaching step is a step in which two pre-fabricated parts are assembled together in case the bristled part is manufactured before or during manufacturing of the body. 
     According to the invention the pad is a bristled pad consisting of a foil and bristles projecting from a front surface of the foil. The back surface of the foil opposite the front surface is essentially flat. In fact, according to a further embodiment of the invention, the pad is made by assembling together only two components: a pre-fabricated foil and pre-fabricated bristles, such as tufts of bristle hairs/fibers. The foil is pliably, i.e. supple bending, so that it can easily follow the curvatures of the recess—the curvature due to the J-shaped or U-shaped length direction of the recess and/or the curvature due to the U-shaped cross section of the recess—and therefore has a thickness of at most 700 μm. Such a thickness also does not use much space in the mouthpiece. Further the fixed ends of the bristles—i.e. the ends opposite the free ends of the bristles projecting into the recess of the mouthpiece to be manufactured—are fused to the foil, in other words attached to the foil by fusing the fixed ends of the bristles and the foil. This results in a bristled pad made from assembling a foil and bristles. Due to the fused connection the connection between bristles and foil is strong. Due to the pliability of the foil it is easy to attach the pad into the recess whilst the back surface of the foil follows the shape of the surface of the bristle carrier to which it is attached. Due to the small thickness of the foil, a significant increase in mouthpiece dimension is prevented. 
     According to a further embodiment of the first aspect of the invention, the thickness of the prefabricated foil is at most 400 μm, or at most 250 μm such as at most 150 μm. According to another further embodiment of the first aspect of the invention, the prefabricated foil has a thickness of at least 50 μm in order to ensure the foil to be sufficient strong. Taking into account the presently anticipated fusing techniques, it seems that the prefabricated foil may have a thickness in the range of 50-250 μm, such as in the range of 50-150 μm, whilst still providing sufficient retention force to prevent on the one hand bristles from separating from the foil and on the other hand foil parts with bristles from separating from the rest of the foil due to locally tearing or breaking of the foil. 
     When fusing the bristles with (or to) the prefabricated foil, the thickness of the foil may increase due to melt originating from the fixed ends of the bristles. Taking this into account, the invention may in addition or alternatively be defined in terms of thickness of the foil of the bristled pad, i.e. the foil after fusing it with the bristles:
     Thus, according to a further embodiment of the first aspect of the invention, the bristled foil may in addition be defined as having as thickness of at most 1.5 mm, such as at most 1 mm or at most 750 μm. This thickness of the bristled foil is the thickness of the foil in the resulting pad exclusive the length the bristles. In other words the bristles itself are not part of the thickness.
 
Thus, according to an alternative for claim  1 , the first aspect of the invention may be defined as “Method of manufacturing a mouthpiece for simultaneously brushing at a plurality of dental positions, the mouthpiece being of the type comprising a body defining a recess which is lined with bristles and has a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction;
   

     wherein the method comprises a pad manufacturing step in which at least one pad with bristles is made; the pad consisting of a pliable plastic foil and plastic bristles projecting from a front surface of the foil; the foil having a back surface opposite the front surface; and the pad manufacturing step comprising
         providing bristle with a fixed end and a free end,   providing a prefabricated foil, and   fusing the fixed ends of the bristles with the prefabricated foil,
 
resulting in a bristled pad with a foil having a thickness of at least 1.5 mm, such as at least 1 mm or at least 750 μm;
       

     wherein the method further comprises a body providing step in which a body of the mouthpiece to be manufactured is provided; the body providing step comprising providing a body with a recess and at least one bristle carrier; the recess having a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction and being configured for encompassing a dental arch of multiple dental positions; the at least one bristle carrier delimiting the recess; and 
     wherein the method further comprises a pad attaching step in which during or after the body providing step one or more bristled pads are attached to the at least one bristle carrier to line the bristle carrier with bristles; the back surface side of the foil facing the bristle carrier and the front surface side of the foil facing away from the bristle carrier into the recess.” 
     The values for the thickness of the prefabricated foil as mentioned in claims  1 - 4  may—separate of the rest of the features of claims  1 - 4 —be further embodiments of this alternative for claim  1 . 
     According to another further embodiment of the first aspect of the invention, the pliable foil of the bristled pad has a bending resistance of less than 2 Newton—such as less than 1.3 Newton or less than 0.5 Newton—, the bending resistance being defined as the force F required to bend a strip of foil having a width W of 10 mm and length L of 20 mm over a distance Q of 10 mm, the force F being directed in the direction opposite to the direction in which the free ends of the bristles are facing. As follows from the low force in this bending resistance, the foil will easily adapt itself to the surface of the bristle carrier to which it is attached. This facilitates not only the pad attachment step, but also adaptation of the foil to the shape of the teeth of the user. 
     According to another further embodiment of the first aspect of the invention—in which the mouthpiece to be manufactured has two said recesses, the J-shaped or U-shaped length directions of both recesses extending parallel and the U-shaped cross-sections of both recesses opening in mutually opposite direction—the body providing step comprises providing a body with two said recesses, the J-shaped or U-shaped length directions of both recesses extending parallel and the U-shaped cross-sections of both recesses opening in mutually opposite direction, each said recess having at least one bristle carrier delimiting the respective recess; and the pad attaching step comprises attaching one or more said pads to the at least one bristle carrier of each said recess. A mouthpiece with two such recesses allows simultaneously cleaning of the dental positions (with or without teeth) of the maxillary dental arch and the mandibular dental arch. 
     The bristles may according to the first aspect of the invention be made from materials that are frequently used for bristles of toothbrushes because of their stiffness, bend recovery, chemical resistance and abrasive resistance. These materials which according to the invention may be used for the bristles comprise the following plastics: polyamide (PA), such as all types of nylon like PA6, PA66, PA610, PA612, PA11, PA12; polyethylene terephthalate (PBT); polypropylene (PP); polyester (PE); Polystyrene (and styrene copolymers) (PS); polyurethane (PU), amongst which TPU; polyvinylidene chloride (PVC); and TPE. According to a specific embodiment of the first aspect of the invention, the bristles comprise polybutylene terephthalate (PBT) or polyamide (PA) fibers, such as nylon fibers. Bristles of these materials have properties providing good cleaning action when brushing the teeth. The bristles are stiff (relatively large bending resistance) which contributes in the scrapping action of the free ends of the bristles. 
     According to another further embodiment of the invention wherein the bristles comprise fibers of a first material and wherein the front surface side of the foil, also called the bristled surface side of the foil, comprises a second material fusible with the first material. The second material may, according to a further embodiment of the first aspect of the invention, be similar—but not necessarily identical—to the first material. The second material may according to a further embodiment be a polybutylene terephthalate (PBT) or polyamide (PA), such as nylon. As an example of the first material being similar—but not identical—to the second material, nylon may be mentioned as first material for the bristles and polyamide for the second material of at least the front surface of the foil. The foil may be made of one material or multiple materials. The foil may comprise for example two or three layers of different material. 
     According to another further embodiment of the first aspect of the invention the foil of the pad is fused with the bristle carrier in the pad attaching step. The bristle carrier and pad, more precisely the foil of the pad, then become so to say one integral part, which further improves the retention force against bristles from separating from the body. 
     According to another further embodiment of the first aspect of the invention, the bristle carrier is of a third material not-fusible with the bristles and/or the front surface of the foil, wherein the foil comprises a first outer layer of a material fusible with the bristles and a second outer layer of a fourth material fusible with the third material. In case of the embodiment in which the bristles are of a first material and the front surface side of the foil, also called the bristled surface side of the foil, comprises a second material fusible with the first material, this means that the bristle carrier is of a third material not-fusible with the first material and/or second material, and that the foil comprises a first outer layer of the second material and a second outer layer of a fourth material fusible with the third material. In these further embodiments, the foil is multi-layered with the first outer layer at the front surface of the foil and the second outer layer at the back surface of the foil. The first and second outer layer may be directly joined to each other, or one or more intermediate layers may be provided between the first and second outer layer. The foil with said first outer layer configured to be fusible with the bristles and said second outer layer configured to be fusible with the bristle carrier, allows attachment of bristles to the carrier by fusing materials together from a material in cases in which the bristles and carrier are from a materials which do fuse together not or which when fused together do not provide a reliable attachment. 
     The fourth material may, according to a further embodiment of the first aspect of the invention, be similar—but not necessarily identical—to the third material. 
     According to another further embodiment of the first aspect of the invention, the fourth material is a polypropylene (PP), a polyethylene (PE), a thermoplastic elastomer (TPE), or a thermoplastic polyurethane (TPU). 
     According to another further embodiment of the invention the third material is a polypropylene (PP), a polyethylene (PE), a thermoplastic elastomer (TPE), or a thermoplastic polyurethane (TPU). 
     As an example of the fourth material being similar—but not identical—to the third material, TPE may be mentioned as material for the carrier and PP may be mentioned as material for the second outer layer of the foil. 
     According to another further embodiment of the first aspect of the invention, the bristle carrier comprises a polypropylene (PP), a thermoplastic elastomer (TPE), or a thermoplastic polyurethane (TPU). 
     According to another further embodiment of the first aspect of the invention, the foil is of a non-elastic material and/or an essentially inextensible material. 
     According to another further embodiment of the first aspect of the invention, the bristle carrier is of a flexible, elastic material. 
     According to another further embodiment of the first aspect of the invention, the body further comprises at least part of a driving system configured for moving, such as reciprocatingly moving, the bristles provided in the recess with respect to the rest of the body. The reciprocating movement assists in cleaning the dental positions. 
     According to another further embodiment of the first aspect of the invention, the body comprises a pressure chamber or chain of pressure chambers extending along the length of the recess—such as along the full length of the recess—, wherein the wall of the pressure chamber at the side of the recess defines the bristle carrier, wherein the pressure chamber is configured for containing a fluid under pressure; and wherein the body is configured to move the bristle carriers to and fro with respect to the recess by reciprocatingly increasing and decreasing a pressure in the pressure chamber or chain of pressure chambers between a decreased pressure condition and an increased pressure condition. A chain of pressure chambers is understood to be chain extending along the J-shaped or U-shaped length direction, the chain comprising a multiple of—viewed in said J-shaped or U-shaped length direction—aligned pressure chambers. 
     According to another further embodiment of the first aspect of the invention, the pad manufacturing step comprises the following steps: 
     a) providing the bristles; 
     b) providing a said prefabricated foil; 
     c) bringing the fixed ends of the bristles in contact with the foil; 
     d) heating the foil and/or fixed ends of the bristles; 
     e) fusing of the fixed ends of the bristles with the foil resulting in the pad. 
     According to a still further embodiment, the heating of step d) may be by means of plastic welding, such as hot gas welding, heat sealing, hot plate welding, infrared welding, high frequency welding, induction welding, ultrasonic welding, friction welding, spin welding, laser welding, or a combination of one or more of these plastic welding techniques. In hot plate welding a so called heat stamp is used, which is a heated or hot body which is pressed against the bristles and/or foil to cause melting. According to a still another further embodiment, step d) may take place after or before step c). 
     According to another further embodiment of the first aspect of the invention, step a) may comprise the steps of:
         providing a bristles holding tool having a foil support surface and a plurality of bores extending from the foil support surface into the tool, the bores being configured to receive bristles; and   inserting the bristles into the bores such that their fixed ends are at the foil support surface;
 
wherein step c) comprises placing the foil onto the foil support surface; and
 
wherein after step e) the tool is separated from the pad. In the prior art it is known to attach bristles to a carrier by inserting the bristles through perforations in the carrier, and melting the projecting parts of the so called fixed ends of the bristles by means of a heat stamp so that on the carrier a melt layer is formed which is fixed to the carrier. The perforated carrier is thick and rigid and becomes part of the toothbrush construction. This perforated carrier is not a tool which is removed and further the melt layer is not a pre-fabricated foil to which the bristles are attached, but a melt layer formed from melted bristle ends.
       

     According to a second aspect of the invention, one or more of the objects of the invention are achieved by providing a mouthpiece obtained with the method according to the first aspect of the invention. 
     According to a third aspect of the invention, one or more of the objects of the invention are achieved by providing a method of manufacturing a bristled pad consisting of a pliable foil, such as a plastic foil, and bristles, such as plastic bristles, projecting from a front surface of the foil, and the foil having a back surface opposite the front surface; 
     wherein the method comprises the following steps: 
     a) providing bristles with a fixed end and a free end;
 
b) providing a prefabricated foil having a thickness of at most 700 μm, such as at most 400 μm or at most 250 μm or at most 150 μm;
 
c) bringing the fixed ends of the bristles in contact with the foil;
 
d) heating the foil and/or fixed ends of the bristles;
 
e) fusing of the fixed ends of the bristles with the foil resulting in the bristled pad.
 
     According to a further embodiment of the third aspect of the invention, the bristled foil may have a thickness of at most 1.5 mm, such as at most 1 mm or at most 750 μm. 
     According to a further embodiment of the third aspect of the invention, step a) may comprise the steps of: 
     providing a bristles holding tool having a foil support surface and a plurality of bores extending from the foil support surface into the tool, the bores being configured to receive bristles; and 
     inserting the bristles into the bores such that their fixed ends are at the foil support surface; 
     wherein step c) comprises placing the foil onto the foil support surface; and
 
wherein after step e) the tool is separated from the pad.
 
     According to a further embodiment of the third aspect of the invention, the heating of step d) may be by means of plastic welding, such as hot gas welding, heat sealing, hot plate welding, infrared welding, high frequency welding, induction welding, ultrasonic welding, friction welding, spin welding, laser welding, or a combination of one or more of these plastic welding techniques. 
     According to a still further embodiment of the third aspect of the invention, step d) may take place after or before step c). 
     According to a still further embodiment of the third aspect of the invention, the pliable foil of the bristled pad has a bending resistance of less than 2 Newton—such as less than 1.3 Newton or less than 0.5 Newton—, the bending resistance being defined as the force F required to bend a strip of foil having a width W of 10 mm and length L of 20 mm over a distance Q of 10 mm, the force F being directed in the direction opposite to the direction in which the free ends of the bristles are facing. 
     According to a fourth aspect of the invention, one or more of the objects of the invention are achieved by providing a bristled pad obtained with the method according to the third aspect of the invention. 
     According to a further embodiment of the fourth aspect of the invention, the mouthpiece has two said recesses, the J-shaped or U-shaped length directions of both recesses extending parallel and the U-shaped cross-sections of both recesses opening in mutually opposite direction. 
     According to a still further embodiment of the fourth aspect of the invention, the body comprises a pressure chamber or chain of pressure chambers extending along the length of the recess, wherein the wall of the pressure chamber at the side of the recess defines the bristle carrier, wherein the pressure chamber is configured for containing a fluid under pressure; and wherein the body is configured to move the bristle carriers to and fro with respect to the recess by reciprocatingly increasing and decreasing a pressure in the pressure chamber or chain of pressure chambers between a decreased pressure condition and an increased pressure condition. 
     According to a fifth aspect of the invention, one or more of the objects of the invention are achieved by providing a dental cleaning device comprising a mouthpiece according to the fourth aspect of the invention and a pressure and/or suction device which is configured to be in fluid communication with the pressure chamber or chain of pressure chambers and configured for reciprocatingly increasing and decreasing the pressure in the pressure chamber. 
     In this application the term ‘pliable’ in relation to the foil is used in the meaning of supple so that it is able to bend freely and repeatedly without breaking. It may for example be a foil, like the foil of a sandwich bag, which already bends or even—when kept horizontal—tends to assume a vertical position under influence of its own weight. It may also be a foil which has a stiffness enough to allow it be kept horizontal, but bendable under influence of small forces. 
     In this application the term ‘bristled’ used as an adjective before a noun like part, pad, foil, or carrier means a part, pad, foil, or carrier, respectively, provided with bristles. 
     In this application the term ‘bristle’ or ‘bristles’ is used to indicate a single bristle hairs or fibers as well as to indicate tufts of bristle hairs or bristle fibers. 
     In this application the term ‘fixed end’ of a bristle (or tuft or bristle fiber) is used to indicate one of the ends of the bristle, namely which is—depending on the stage in manufacturing of the bristled pad—(still) to be fixed or is (already) fixed to the pliable foil. The term ‘fixed end’ does not say that, in case of for example a tuft, these ends of the bristle fibers of the tuft are mutually fixed. The fixed ends of the bristle fibers of a tuft may or may not be mutually fixed. For example, after manufacturing the bristled pad, the fixed ends of the bristled fibers of a tuft may in general be mutually being fixed due to fusing together, but, in the stage before fusing the fixed ends to the foil, the fixed ends of the bristle fibers of a tuft may, although combined in a tuft, not yet be attached to each other. However, it is according to the invention conceivable that the so called fixed ends of the bristle fibers in a tuft are already attached to each other in the stage before fusing the fixed ends to the foil. 
     Summarizing, the present invention relates thus relates to the manufacturing of a bristled pad for a mouthpiece toothbrush, a bristled pad, the manufacturing of a mouthpiece toothbrush with such a bristled pad, and a mouthpiece toothbrush. The bristled pad is manufactured from a prefabricated foil and prefabricated bristles. The prefabricated bristles are attached to the prefabricated pliable foil of at most 700 μm by fusing the fixed ends of the bristles with the foil, which results in a pliable bristled pad. In the method of manufacturing the mouthpiece, the pliable, bristled pad is attached to the body of the mouthpiece. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The invention will be explained further with reference to the drawings. In these drawings: 
         FIG.  1    shows a lower dental arch with dental positions and a system of three orthogonal axes defining a dental arch. 
         FIGS.  2   a ,  2   b  and  2   c    show an example of a full U-shaped mouthpiece with a bristled pad made with the method according to the invention, wherein  FIG.  2   a    shows a perspective view,  FIG.  2   b    shows a cross-sectional view according to the arrows IIb in  FIG.  2   a   , and  FIG.  2   c    shows a cross-sectional view according to the arrows IIb in  FIG.  2     a.    
         FIGS.  3   a , and  3   b    show an example of a half J-shaped mouthpiece with a bristled pad made with the method according to the invention, wherein  FIG.  3   a    shows a perspective view, and  FIG.  3   b    shows a cross-sectional view according to the arrows IIb in  FIG.  2     a.    
         FIGS.  4   a , and  4   b    show, as a variant of  FIG.  2   , an example of a full U-shaped mouthpiece with a bristled pad made with the method according to the invention, wherein  FIG.  4   a    shows a cross-sectional view according to the arrows IIb in  FIG.  2   a   , and  FIG.  4   b    shows a cross-sectional view according to the arrows IIb in  FIG.  2     a.    
         FIG.  5    schematically shows an embodiment of a dental cleaning device according to the invention; 
         FIG.  6    elucidates the definition of the term ‘bending resistance’ as it used in this application as well as the claims. 
         FIG.  7    shows two bristled pads according to the invention, one in a flat condition and one in a bended condition. 
         FIG.  8    shows two bristled pads according to the invention in the form of bristled strips,  FIG.  8   a    showing the strips in flat condition and  FIG.  8   b    showing the strips in a bended condition. 
         FIG.  9    shows two sets of bristled strips according to the invention,  FIG.  9   a    showing the sets in flat condition and  FIG.  9   b    showing the sets in a bended condition. 
         FIGS.  10 - 16    show schematically examples of different manners for manufacturing a bristled pad according to the invention. 
         FIG.  10    shows a first example of manufacturing a bristled pad,  FIG.  10   a    showing a first state,  FIG.  10   b    showing a second state, and  FIG.  10   c    showing a third state. 
         FIG.  11    shows a second example of manufacturing a bristled pad,  FIG.  11   a    showing a first state, and  FIG.  11   b    showing a second state. 
         FIG.  12    shows a third example of manufacturing a bristled pad. 
         FIG.  13    shows a fourth example of manufacturing a bristled pad,  FIG.  13   a    showing a first state,  FIG.  13   b    showing a second state, and  FIG.  13   c    showing a third state. 
         FIG.  14    shows a fifth example of manufacturing a bristled pad. 
         FIG.  15    shows bristled pad according to the invention, having a multi-layered foil. 
         FIG.  16    shows a sixt example of manufacturing a bristled pad,  FIG.  16   a    showing a first state,  FIG.  16   b    showing a second state,  FIG.  16   c    showing a third state, and  FIGS.  16   d  and  16   e    each showing a fourth state with mutually slightly different resulting bristled pad. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG.  1    shows in perspective view, highly schematically a part of an upper dental arch  1  with dental positions  2 - 14 . Each dental position is indicated with a vertical dashed line. Each dental position usually comprises a tooth which is named according to a nomenclature known to each dentist. Using this nomenclature: 
     dental position  2  is the position of the left ‘second molar’, present in  FIG.  1   ; 
     dental position  3  is the position of the left ‘first molar’, missing in  FIG.  1   ; 
     dental position  4  is the position of the left ‘second premolar’, present in  FIG.  1   ; 
     dental position  5  is the position of the left ‘first premolar’, present in  FIG.  1   ; 
     dental position  6  is the position of the left ‘canine’, present in  FIG.  1   ; 
     dental position  7  is the position of the left ‘lateral incisor’, missing in  FIG.  1   ; 
     dental position  8  is the position of the left ‘central incisor’, present in  FIG.  1   ; 
     dental position  9  is the position of the right ‘central incisor’, present in  FIG.  1   ; 
     dental position  10  is the position of the right ‘lateral incisor’, present in  FIG.  1   ; 
     dental position  11  is the position of the right ‘canine’, present in  FIG.  1   ; 
     dental position  12  is the position of the right ‘first premolar’, present in  FIG.  1   ; 
     dental position  13  is the position of the right ‘second premolar’, present in  FIG.  1   ; 
     dental position  14  is the position of the right ‘first molar’, present in  FIG.  1   ; 
     In  FIG.  1    the dental position of the right ‘second molar’ is not shown, and also the dental positions of the right and left ‘third molar’, also called wisdom tooth, are not shown. Similar the lower jaw has a similar number of dental positions, which are in accordance with said nomenclature similarly named. 
     Reference number  15  indicates the lingual side of the arc of dental positions. The lingual side  15  is the inner side of the arc of dental positions, which inner side faces the tongue. Reference number  16  indicates the facial side of the arc of dental positions. The facial side  16  is the outer side of the arc of dental positions, which outer side faces the face, like the cheeks and lips. 
       FIG.  1    further shows a system of three mutually orthogonal axes, comprising an x-axis X, an y-axis Y and a z-axis Z. The z-axis Z is a curved axis following the contour of the dental arch  1 . The x-axis X and y-axis Y are perpendicular to each other and define an xy-plane which is essentially flat and perpendicular to the dental arch  1 , i.e. each xy-plane intersecting a location on the z-axis is, at that location, perpendicular to the curved z-axis Z. The z-axis Z defines a curved length direction. The z-axis Z and y-axis Y define a curved zy-plane, with viewed along the z-axis, an arc-shape similar to shape of the dental arc. Further, the z-axis Z and x-axis X define a zx-plane and the x-axis X and y-axis Y define an xy-plane. 
     Referring to the terms ‘J-shaped or U-shaped length direction’ and ‘U-shaped cross-section’ as used in the claims, the ‘J-shaped or U-shaped length direction’ is associated to the U-shaped z-axis Z in  FIG.  1    and the ‘U-shaped cross-section’ is associated with the xy-plane in  FIG.  1   . 
       FIG.  2   a    shows schematically a perspective view of an example of a so called full mouthpiece  20  made with the method according to the invention.  FIG.  2   b    shows schematically a cross section of the mouthpiece of  FIG.  2   a   , viewed as indicated by arrows IIb in  FIG.  2     a.    
     The full mouthpiece  20  comprises a body  21  provided with a first recess  22   a . This first recess  22   a  has, viewed along the z-axis of  FIG.  1   , an U-shaped length direction and, viewed in the xy-plane of  FIG.  1   , an U-shaped cross section. The first recess  22   a  is delimited by a recess wall  23 , which is in the xy-plane U-shaped. The recess wall  23  is lined with a plurality of bristles  24 . The bristles shown in  FIG.  2    are tufts  29  of bristle fibers  24 . The bristle fibers may for example be a PA fibers, such as a nylon fibers, or a PBT fibers, or a mixture of these fibers. But also fibers from other materials or mixture of fibers from other materials with or without fibers of PA, such as nylon, and/or PBT are conceivable. Each bristle, such as tuft of fibers, has one end, called the fixed end  19 , attached to the recess wall  23  and extending from the recess wall  23  into the first recess  22   a.    
     Reference  26  indicates a nipple configured for connecting the mouthpiece to a pumping and/or suctioning device. The mouthpiece  20  further has a right half  27  and a left half  28 , which halves come so to say together at nipple  26 . 
     Reference  25  indicates an imaginary curved dividing line, which defines a mirror plane parallel to the xz-plane as defined in  FIG.  1   . The mouthpiece as shown in  FIG.  2    is so to say about mirror symmetrical with respect to this mirror plane, meaning that there is a second recess  22   b  (not visible in  FIG.  2   a    but visible in  FIG.  2   b   ) opposite the first recess  22   a , which second recess  22   b  is lined with bristles as well. It is noted that the first recess  22   a  may have a shape different than the shape of the second recess  22   b  because the (teeth of the) upper and lower arc of dental positions have different shapes. The term ‘mirror symmetrically’ above thus is not used in the strict mathematical sense but just in the sense that there are two recesses, each on one side of the mirror plane. 
     The recesses  22   a ,  22   b  are configured to encompass an entire dental arch from the dental position of the right second or first molar to the dental position of the left second respectively first molar. The recesses  22   a ,  22   b  may also be configured to encompass a larger or smaller part of an arch of dental positions. 
       FIG.  2   b    shows a cross-section according to arrows Ilb in  FIG.  2   a    of a right part of the mouth piece  20 . 
     As can best be seen in  FIG.  2   b   , the bristles may be provided as tufts  29  of relatively thin bristle fibers  24 . Further, it can be seen in  FIG.  2   b    that the bristles are provided on bristled pads consisting of a foil  36   a ,  36   b  and bristles fused with the foil  36   a ,  36   b . The foil in the example of  FIG.  2    is a multi-layer foil with a first outer layer  36   a  and a second outer layer  36   b.    
     As can be seen in  FIG.  2   b   , the mouthpiece  20  has a body  21  having in its upper side a first recess  22   a  and in its lower side a second recess  22   b . Both recesses  22   a ,  22   b  are delimitated by a flexible recess wall  23 . In cross-section parallel to the xy-plane as defined in  FIG.  1   , the recess walls  23  are U-shaped and have a recess wall bottom  34  and two recess wall legs  33  extending from the recess bottom wall. The recess wall  23  is covered with tufts  29  of bristle fibers  24  on the legs  33  and/or bottom  34  of the recess wall  23 . 
     Inside the body there is provided a pressure chamber  35 , which may, via the nipple  26  ( FIG.  2   a   ), be filled with a fluid. The fluid may be a gas, like air, or a liquid, like water. In the embodiment as shown in  FIG.  2   , the mouthpiece has one pressure chamber. It is however noted that the mouthpiece may comprise a plurality of pressure chambers, like 5 pressure chambers, or any other number of pressure chambers. WO-2018/199760 shows examples of other numbers of pressure chambers in  FIGS.  4 ,  5 ,  7 ,  9  and  10   . In case of multiple pressure chambers, all the pressure chambers or groups of pressure chambers may according to the invention be in fluid communication with each other, similar as is described in WO-2018/199760. Viewed in the U-shaped length direction (i.e. along the z-axis of  FIG.  1   ), a chain of so to say aligned pressure chambers may be provided as well. 
     As can be seen in  FIG.  2   b   , the mouthpiece may comprise an internal support structure of a material which is rigid relative to the material of the recess wall  23 . This support structure may structure comprise a lingual plate  30  and a facial plate  32 , both extending essentially parallel to the curved zy-plane defined in  FIG.  1    and consequently, viewed along the z-axis, having a U-shape. In order to keep the lingual plate  30  and facial plate  32  at a distance from each other, the support structure may comprise one or more spacers  31 . These one or more spacers  31  may for example be a multiple of bars or wires or a single plate which may extend essentially parallel to the zx-plane as defined in  FIG.  1   . In case of a single plate as spacer, this plate may divide the pressure chamber  35  in two pressure chambers, an upper one and a lower one. These two pressure chambers may be in fluid communication with each other via one or more through holes through the plate. In case of large through holes and/or a large number of through holes the two pressure chambers may effectively be one single pressure chamber. 
     The mouthpiece as shown in  FIG.  2    is configured for simultaneously brushing at a plurality of dental positions. In case a tooth is present, the tooth of the respective dental position will be brushed. The remnants at a dental position, like the gum, may be brushed in case a tooth may be missing and the teeth adjacent the location of the missing tooth may be additionally brushed by bristles intended for the location of the missing tooth. 
     The single pressure chamber  35  comprises a first flexible recess wall  23  delimiting the first recess  22  (the upper one in  FIG.  2   b   ) and a second flexible recess wall  23  delimiting the second recess  22  (the lower one of  FIG.  2   b   ). The first and second recess walls are deformable, in particular by increasing or decreasing the pressure in the pressure chamber  23 . The flexible recess walls  23  may be made from an elastic material, such as a rubberlike material. The flexible recess walls  23  may also be made from a non-elastic material. Examples of suitable materials for the recess wall are PP, a PE, a TPE, a TPU. The material of the flexible recess walls  23  may keep a predetermined shape when there is substantially no, or a low, pressure difference across an inner side and an outer side of the flexible recess walls  23 . 
     The mouthpiece  20  is configured for the tufts  29  to engage the tooth surface of teeth of a dental arch or, in case one or more dental positions the tooth might be missing, to engage the gum at the respective dental position(s) at least when the pressure in the pressure chamber  35  is increased. In case a tooth might be missing at a dental position, especially the tufts  29  at the free ends of the recess wall legs  33  will engage the gum at the empty dental position. 
     Viewed in length direction Z of the dental arch—as defined in  FIG.  1   —, the tufts  29  of bristle fibers  24  may be arranged at about the same density as viewed in the cross-sections shown in  FIG.  2     b.    
       FIG.  2   c    shows that at dental location of the incisors the bottom of the U-shaped recess  22   a  and  22   b  may in fact be open (or, not shown, V-shaped). In this ‘open embodiment’, the first recess  22   a  and second recess  22   b  are in open connection with each other. To prevent the lingual side  30  of the body and the facial side  32  of the body from widening away from each other, some spacer  31  may still be provided at the dental position of the incisors, but this spacer  31  may also be left away. 
     When the pressure in the pressure chamber  35  is in increased to an increased pressure condition, for example by feeding a fluid to the pressure chamber  35 , or increasing an amount of fluid in the pressure chamber  35 , the recess walls  23  are so to say compacted to narrow the recess  22 , whereby the bristles  24 , 29 , in particular the free ends thereof, may engage tooth surfaces firmly and/or may be deformed against tooth surfaces. When the pressure in the pressure chamber  35  is decreased subsequently, the recess walls are so to say widened to enlarge the recess  22 . This narrowing and widening of the recess walls may be small, but when alternatingly repeated with some frequency of for example 1 to 50 Hz, this alternatingly deforming of the recess wall by alternatingly narrowing and widening it, causes the bristles to move between a firmer and relatively less firm engagement with tooth surfaces and/or the bristles to alternate between a first and second deformed condition, which in turn causes a sweeping and/or rubbing of bristles along the tooth surfaces. 
     By a suitable cycle of increasing and decreasing pressure in the pressure chamber  35  an effective brushing action of the mouthpiece can be obtained. The bristles  24  attached to the recess wall bottom  34  generally perform an upward and downward motion during such cycling, and the bristles  24  at the recess wall legs  33  generally perform a sideways motion to and fro during such cycling in the direction of the x-axis as defined in  FIG.  1   . Due to the recess  22   a ,  22   b  alternatively narrowing and widening when alternatingly increasing and decreasing pressure, the bristles  24  at the recess wall legs may also be subjected to a back and forth pivoting around the z-axis as defined in  FIG.  1   , resulting in a sweeping and/or rubbing movement of the bristles in the direction of the y-axis as defined in  FIG.  1   . 
     Referring to  FIG.  1   , the width of a teeth element in the X direction varies, depending on the dental position between about 2 to 8 mm. Taking into account hat t is desired to keep the mouthpiece as small as possible, the width of the recess in the X direction is to be kept as small as possible and may be about 0 to 2 mm wider than the width of the respective tooth. The bristles may be 2 to 4 mm long, meaning that between the bristles extending from opposing recess wall legs  33  no interspace or a limited amount of interspace of about 2-4 mm is left. In  FIGS.  2   , these interspaces are shown exaggerated. This limited amount of interspace makes it difficult to manufacture a mouthpiece as shown in  FIG.  2    in economical manner. Injection moulding for example is difficult due to the bristles extending from the opposing recess wall legs extend essentially in the X direction which is transvers to the direction in which injection moulding moulds may be separated from each other after moulding. 
       FIG.  3    shows a so called half mouthpiece  20 . The difference with the mouthpiece of  FIG.  2   a    is basically that the right half of  FIG.  2   a    has been left away, resulting in a J-shaped, half mouthpiece. With a J-shaped half mouthpiece, all dental positions of the right half of the dental positions can be cleaned in one go. After taking the mouthpiece out of the mouth, turning it around and inserting it in the mouth again, also the left half of the dental positions can be cleaned (or vice versa, first cleaning the right half and then the left half). The half mouthpiece also comprises a body  21  provided with a first recess  22   a  and  22   b , however, the first recess  22   a  and second recess  22   b  have, viewed along the z-axis of  FIG.  1   , an J-shaped length direction and, viewed in the xy-plane of  FIG.  1   , an U-shaped cross section. 
     For the rest, the mouthpiece of  FIG.  3    is basically the same as the mouthpiece of  FIG.  2   , except that in  FIG.  3    the foil  36  of the bristled pad is a foil of one layer, whilst in the embodiment of  FIG.  2    the foil has two (or more) layers, a first outer layer  36   a  and a second outer layer  36   b . It is however to be noted that in the embodiment of  FIG.  2    also bristled pads with single layer foil can be used and that in the embodiment of  FIG.  3    also bristled pads with multi-layer foils can be used. 
     Moving the bristles to and fro with respect to the recess(es) is realised by means of a drive system, at least part of which is arranged in the mouthpiece. The drive system may be a mechanical system causing movement of the bristles. An example of a mechanical drive system is shown in  FIG.  4   .  FIG.  4   b    can be considered as a variant of  FIG.  2   b    and  FIG.  4   b    can be considered as a variant of  FIG.  2   c   . In this embodiment the body with mechanical drive the body may for example be a solid mass  38  in which a vibration element  37  is provided as part of the drive system. This vibration element may be set into vibration by a handle mounted at  26  with a vibrating interface, which interface in turn is set into vibration by a motor provided in the handle. 
     Now returning to the embodiment shown in  FIGS.  2  and  3   , the drive system for moving the bristles to and fro with respect to the recess(es) is realized by increasing and decreasing the pressure in the pressure chamber  35 , which is effected by a pump unit. Different pump unit and valve combinations are possible. One possible embodiment is by way of example explained with reference to  FIG.  5   . 
       FIG.  5    schematically depicts, in a partially cut-away perspective view, a dental cleaning device  200  comprising a handle member  202  and a mouthpiece  100  coupled thereto, e.g. a mouthpiece as described in the above. The handle member  202  is provided with a handle interface  204 , and the mouthpiece  100  is provided with a mouthpiece interface  203  configured to be detachably coupled to the handle interface  204 . The handle member  200  comprises a battery  210  for storing electrical energy which can be fed to the battery  210  through a battery charging interface  212 . The battery  210  provides energy to a printed circuit board, PCB,  214 , to a pump unit comprising a motor  216 , a transmission  218 , a crank piston  220  and a piston pump  222 , and to optionally a mouthwash pump  224 . A mouthwash capsule  230  containing a mouthwash liquid may be removably accommodated in the handle member  200 . The piston pump  222  may be a pneumatic pump. Instead of a piston pump also a diaphragm pump, a plunger pump, a membrane pump, or bellows pump may be used. The mouthwash pump  224  may be a hydraulic pump. 
       FIG.  6    serves the purpose of illustrating the definition of the term ‘bending resistance’ as it is used in the claims as well as the description of this application. Black rimmed in gray a sample strip of foil is shown. As shown, this sample strip has a width W and a length L. The sample strip is fixed at its left end A and extends from A horizontally to the right without any support. The sample strip thus represents a so called ‘cantilever beam’. When a downward force F is exerted on the right end of this sample strip/cantilever beam, the strip/beam will deflect to a deflected condition, which is shown in dashed line in  FIG.  6   . In deflected condition, the right end of the strip/beam lies a vertical distance Q below the right end of the strip/beam in unloaded condition. The bending resistance of the foil is in this application defined in terms of a distance Q which a sample strip of foil having predetermined dimensions W and L bends upon exerting a predetermined force F transverse to the foil. The force F is in this definition directed in the direction opposite to the direction in which the free ends of the bristles are facing. This direction of the force F means that the foil is bended such that the bristles are on the convex side of the bended foil, as is indicated by the in this example four bristles shown in  FIG.  6   . Doing so, the bending resistance of the pliable foil is defined as X Newton, when a force F of X Newton is required to bend a strip of said foil having a width of 10 mm and a length of 20 mm over a distance Q of 10 mm, the force F being directed in the direction in which the free ends of the bristles are facing. 
     The definition illustrated in  FIG.  6   , may be used in similar manner to define the stiffness of a bristle fiber for example as follows: ‘the fiber having a stiffness of X Newton, when a force F of X Newton is required to bend a bristle fiber having a length of 1 cm over a distance Q of 0.2 cm’. 
       FIG.  7    shows two bristled pads  50  according to the invention. The pad  50  on the left is in flat condition and the pad  50  on the right is in a bended condition. Referring to the definition of ‘bending resistance’ as elucidated in  FIG.  6   , also the bended pad on the right of  FIG.  7    has its bristles on the convex side. However, it is to be noted that the pad may also be bended in opposite direction, as is for example shown in  FIGS.  8   b  and  9   b   , see the bristled pads  60  respectively  70 . 
     As shown in  FIG.  7   , the bristled pad  50  according to the invention consists of a pliable foil  51  with tufts  52  of bristle fibers. The foil  51  may have a thickness T of 40-150 μm. Further the bending resistance of the foil may for example be less than 1.3 Newton or even less than 0.5 Newton. The foil  51  has a front surface  53  from which the bristles (tufts) project. Opposite the front surface the foil  51  has a back surface  54 . Each bristle has a fixed end  55  where the bristle  52  is fused to the foil  51  and a free end  56  facing away from the foil. 
       FIG.  8    shows two bristle pads  60 ,  61  which, in cross section transverse to  FIG.  8   , may be in accordance with  FIG.  7   . The bristled pads  60 ,  61  are in this example in the form of elongate bristled strips, a first strip  60  and a second strip  61  which is—as can be seen good in  FIG.  8   a   —a little shorter than the first strip  60 .  FIG.  8   a    shows both bristled strips in a flat condition and  FIG.  8   b    shows both strips in a bended condition as they may have when attached in the body (not shown) of the mouthpiece. The longer strip  60  is to be attached to the facial side—i.e. the outer side—of the recess and the shorter strip is to be attached to the lingual side—i.e. the inner side—of the recess. Referring to the embodiment of  FIG.  2   , the strips  60  and  61  are to be attached to the flexible recess wall  23 , strip  60  on one of the wall legs  33  and strip  61  on the opposing wall leg  33 . The strips  60  and  61  may be attached to the recess wall  23  by fusing the strips along their back surface  54  onto the recess wall  23 . This may for example be achieved by inserting the strips  60  and  61  as a pre-fabricated part into a mould for injection moulding the recess wall  23  and possibly more parts of the body of the mouthpiece. When the material for the recess wall is injected into the mould, this material may fuse with the foil or at least the back side  54  of the foil. In similar manner a single bristled strip for the recess wall bottom  34  may be provided and attached to the recess wall bottom  34 . 
       FIG.  9    shows two sets  70 ,  71  of multiple bristle pads, which, in cross section transverse to  FIG.  9   , may be in accordance with  FIG.  7   . The sets  70 ,  71  of bristled pads  60 ,  61  are in this example in the form of three elongate bristled strips  70   a ,  70   b ,  7   c  and  71   a ,  71   b ,  71   c . The first set  70  of bristled strips  70   a ,  70   b ,  70   c  is—as can be seen good in  FIG.  9   a   —a little shorter than the second set of bristled strips  71   a ,  701   b ,  71   c .  FIG.  9   a    shows both sets of bristled strips in a flat condition and  FIG.  9   b    shows both sets of bristled strips in a bended condition as they may have when attached in the body (not shown) of the mouthpiece. The longer set  70  is to be attached to the facial side—i.e. the outer side—of the recess and the shorter set  71  is to be attached to the lingual side—i.e. the inner side—of the recess. Referring to the embodiment of  FIG.  2   , the bristled strips  70   a ,  70   b ,  70   c  and  71   a ,  71   b ,  71   c  are to be attached to the flexible recess wall  23 , strips  70   a ,  70   b ,  70   c  on one of the wall legs  33  and strips  71   a ,  71   b ,  71   c  on the opposing wall leg  33 . The strips  70   a ,  70   b ,  70   c  and  71   a ,  71   b ,  71   c  may be attached to the recess wall  23  by fusing the strips along their back surface  54  onto the recess wall  23 . This may for example be achieved by inserting the strips  70   a ,  70   b ,  70   c  and  71   a ,  71   b ,  71   c  as a pre-fabricated part into a mould for injection moulding the recess wall  23  and possibly more parts of the body of the mouthpiece. When the material for the recess wall is injected into the mould, this material may fuse with the foil or at least the back side  54  of the foil. In similar manner a set of multiple bristled pads for the recess wall bottom  34  may be provided and attached to the recess wall bottom  34 . 
     Referring to  FIGS.  8  and  9    it is noted that a single bristled strip  60  or  61  according to  FIG.  8    may be combined with a set  71  respectively  70  of bristled strips according to  FIG.  9   . The same applies for the single bristled strip at the recess bottom  34  respectively the set of bristled strips for the recess bottom. 
       FIGS.  10 - 14 , and  16    show different examples of manufacturing a bristled pad according to the invention. These examples have in common that a bristle holding tool  80  with perforations or bores is used, that a pre-fabricated foil  81  is provided, that prefabricated bristles  82  are provided, that the pre-fabricated bristles  82  are inserted into the perforations/bores of the tool, that the prefabricated bristles  82  and prefabricated foil are attached to each other by fusing the fixed ends  84  of the pre-fabricated bristles  82  with pre-fabricated foil  81 , and that after having the fixed ends of the bristles fused with the foil the tool  80  is removed. The difference between the examples is in the manner of heating the fixed ends of the bristles and or the foil for fusing them together. 
     Referring to  FIG.  10    as heat stamp  85  is used. A heat stamp is a body heated electrically, heated by a fluid, or heated in any other manner for example by radiation.  FIG.  10   a    shows an example of a starting configuration, in which the pre-fabricated bristled have been inserted into the perforations/bores of the bristle holding tool, in which the pre-fabricated foil is at a distance above the tool  80  and above the fixed ends  84  of the bristles, and in which the heat stamp may already be at its operating temperature.  FIG.  10   b    shows a fusing configuration, in which the pre-fabricated foil  81  has been placed on top of the fixed ends of the bristles  82 , and in which the heat stamp  85  is pressed onto the back surface of the foil. The heat of the heat stamp causes the fixed ends  84  of the bristles to fuse with the foil, such as with the front surface of the foil.  FIG.  10   c    shows the fabricated condition of the bristled pad, in which the bristle holding tool has been removed from the bristled pad. 
     Referring to  FIG.  10   , it is also conceivable to use a perforated pre-fabricated foil, the perforations in the foil having the same pattern as the perforations/bores of the tool. In this case the foil  81  is placed onto the tool such that the fixed ends  84  of the bristles extend into the perforations of the foil and possibly project above the foil. The heat stamp  85  will then in the condition of  FIG.  10   b    press directly onto the fixed ends  84  of the bristles  82 , causing these to melt and fuse with the foil. 
     Referring to  FIG.  11   , a heating source  86  is—see  FIG.  11    a—placed between the pre-fabricated foil  81  and the fixed bristle ends  84  to heat the foil at its front surface  53  and to heat the fixed ends  84  of the bristles  82 . After having the foil and fixed ends of the bristles heated sufficiently, the heat source is removed and the heated foil is placed onto the heated ends of the bristles to allow them to fuse together, see  FIG.  11   b   . This may be facilitated by a stamp, which may be heated, which exerts a pressure on the back surface of the foil. When the bristle ends are fused with the foil, the bristled pad obtained is removed from the tool (not shown in  FIG.  11   ). Like with the example of  FIG.  10   , it is also conceivable to use a pre-fabricated, perforated foil in the example of  FIG.  11   . The heating source  86  of  FIG.  11    may be any type of heating source, like a heated body, an infra-red source, an electrical heating element, hot gas etcetera. 
     Referring to  FIG.  12   , the pre-fabricated foil is placed between the fixed ends  84  of the bristles and a heating source  86 , which may be of similar type as the heating source  86  of  FIG.  11   . In  FIG.  12    the foil is shown at a distance above the fixed ends  84  of the bristles  82 , but in practice the pre-fabricated foil will be placed on top of the fixed ends when the back surface  54  of the foil is heated by the heat source  86 , which is as shown arranged at a distance from the foil  81  during the heating. The heating will cause the ends  84  of the bristles  82  to fuse with foil  81 . The fusing may be further facilitated by pressing, at the end of the heating process, a stamp against the back surface  54  of the foil. Like with the example of  FIG.  10   , it is also conceivable to use a pre-fabricated, perforated foil in the example of  FIG.  12   . The heating source  86  of  FIG.  12    may be any type of heating source, like a heated body, an infra-red source, an electrical heating element, hot gas etcetera. 
     Referring to  FIG.  13   , the fixed ends  84  of the bristles  82  project from the tool  80  and a heating source  86 , like the heating source of  FIG.  10    or  FIG.  12   , is used to melt the fixed ends  84 , see  FIG.  13   a   . This results in the fixed ends  84  forming mushroom shaped heads  87 , see  FIG.  13   b   . These mush room heads  87  prevent the bristles from slipping back into the bores of the tool when the foil  81  is placed on top of the ends  84 /mushroom heads  87 , see  FIG.  13   b   . In order to establish the fusing, the foil is brought into contact with the mushroom heads and pressed downwards by means of a stamp not shown. This results in a bristled pad as shown in  FIG.  13   c   , in the manufactured condition before removing the tool. The heating source  86  of  FIG.  13    may be any type of heating source, like a heated body, an infra-red source, an electrical heating element, hot gas etcetera. 
     Referring to  FIG.  14   , the foil is placed on top of the fixed ends  83  of the bristles supported in the bores of the tool  80 . The heating is done by means of laser, which may fuse each of the fixed ends one by one or group-wise with the foil. Like with the example of  FIG.  10   , it is also conceivable to use a pre-fabricated, perforated foil in the example of  FIG.  14   . 
       FIG.  15    shows an example of a bristled pad having a multilayer foil  81 . This multilayer foil may be a pre-fabricated multilayer foil. The foil  81  has a first outer layer  91  at the front surface side  53  of the foil and a second outer layer  92  at the back side of the foil. The first and second outer layer  91  and  92  may be of a different material. The first outer layer  91  may be of a second material identical to or similar to the first material from which the bristles are made. The second outer layer  92  may be of a fourth material identical to a third material of the bristle carrier of the body. The third material may be a material non-fusible with the first and/or second material, but may also be a material which is fusible with the first and/or second material. Similar the fourth material may be a material non-fusible with the first and/or second material, but may also be a material which is fusible with the first and/or second material. In case the first and second outer layer directly contact each other and the first and second outer layer are fusible with each other, the fusion may be much less strong than the fusion of the bristles with the first outer layer  91  but still strong enough due to the much larger contact surface between the two layers in relation to the cross-sections of the bristles. Referring to  FIG.  13   , it is noted that the foil  81  of the resulting pad of  FIG.  13   c    may very well be a multi-layered foil with a first outer layer  91  formed by the melt originating from the fixed ends of the fibers and a second outer layer  92  provided by the initial foil of  FIG.  13     a.    
       FIG.  16    shows a fourth example of manufacturing a bristled pad. This example is very similar to the example of  FIG.  10   , the main difference being that in the example of  FIG.  16    the prefabricated foil  81  is provided with perforations  93  which mate the pattern of bores  89  in the tool. A further difference is that  FIG.  16    shows the fabrication with a multi layered prefabricated foil having a first outer layer  91  and a second outer layer  92 . However, it is to be noted that also a prefabricated, perforated single layer foil like in  FIGS.  10 - 14    can be used in the example of  FIG.  16   . The other way around, in the examples of  FIGS.  10 - 14    also a prefabricated multilayer foil like the one of  FIG.  16    may be used. 
       FIG.  16   a    shows as a first state, a tool  80  with bores  89 , a foil  81  having two outer layers  91  and  92  of—in this example—mutually different material and a heat stamp  85 . The heat stamp may be replaced by any other heat source  86 . The lower outer layer  91  may, in an embodiment, be of a material with which the bristles do not fuse or hardly do not fuse. 
     In the second state of  FIG.  16   b   , the foil  81  is placed on the tool  80  with the perforations  93  aligned with the bores  89  and with tufts  82  inserted through the aligned bores  89  and perforations  93  such that the fixed ends  84  of the tufts  82  are about flush with the second outer layer  92  or project above the outer layer  92 . 
     In the third state of  FIG.  16   c   , the heat stamp  85  is pressed on top of the fixed ends  84  of the tufts  82  end upper side of the second outer layer  92 , and the fixed ends  87  of the tufts are fused with the second outer layer  92 . Fusing the tufts with the second outer layer  92  instead of fusing them with the first outer layer  91  results in the first outer layer  91  serving as a retention layer preventing tufts from being pulled out. This because the fixed ends of the tufts will be widened a little due to the heat stamp  85  pressing on it. 
       FIG.  16   d    shows an end state in which the upper surface of the bristled foil is embossed. This embossment may be due to the fixed ends  84  of the tufts  82  projecting above the foil as shown in  FIG.  16   b   . As shown in  FIG.  16   e   , it is however also possible to obtain a bristled pad with an essentially flat surface of the second outer layer  92 . 
     Referring to the example of  FIG.  16   , it is to be noted that the foil  81  may also be turned around so that the second outer layer becomes the lower layer and the first outer layer—which does not fuse with the bristles—becomes the upper layer. Then the fixed ends of the bristles will fuse with the lower layer instead of the upper layer. The upper layer may than have no perforations at all. 
     Examples of embodiments of the present invention may be expressed in words as set forth in the next following clauses: 
     1) Method of manufacturing a mouthpiece for simultaneously brushing at a plurality of dental positions, the mouthpiece being of the type comprising a body defining a recess which is lined with bristles and has at least partly a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction;
 
wherein the method comprises a pad manufacturing step in which at least one pad with bristles is made; the pad consisting of a pliable plastic foil and plastic bristles projecting from a front surface of the foil; the foil having a back surface opposite the front surface; and the pad manufacturing step comprising
 
     providing bristle with a fixed end and a free end, 
     providing a prefabricated foil having a thickness of at most 700 μm, and 
     fusing the fixed ends of the bristles with the prefabricated foil, resulting in the bristled pad to be made; 
     wherein the method further comprises a body providing step in which a body of the mouthpiece to be manufactured is provided; the body providing step comprising providing a body with a recess and at least one bristle carrier; the recess having a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction and being configured for encompassing a dental arch of multiple dental positions; the at least one bristle carrier delimiting the recess; and 
     wherein the method further comprises a pad attaching step in which during or after the body providing step one or more bristled pads are attached to the at least one bristle carrier to line the bristle carrier with bristles; the back surface side of the foil facing the bristle carrier and the front surface side of the foil facing away from the bristle carrier into the recess. 
     2) Method according to clause 1, wherein the prefabricated pliable foil has a thickness of at most 400 μm.
 
3) Method according to one of the preceding clauses, wherein the prefabricated pliable foil has a thickness of at most 250 μm, such as at most 150 μm.
 
4) Method according to one of the preceding clauses, wherein the pliable foil has a thickness of at least 50 μm.
 
5) Method according to one of the preceding clauses, wherein the bristled foil has a thickness of at most 1.5 mm, such as at most 1 mm or at most 750 μm.
 
6) Method of manufacturing a mouthpiece for simultaneously brushing at a plurality of dental positions, the mouthpiece being of the type comprising a body defining a recess which is lined with bristles and has a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction;
 
     wherein the method comprises a pad manufacturing step in which at least one pad with bristles is made; the pad consisting of a pliable plastic foil and plastic bristles projecting from a front surface of the foil; the foil having a back surface opposite the front surface; and the pad manufacturing step comprising
         providing bristle with a fixed end and a free end,   providing a prefabricated foil, and   fusing the fixed ends of the bristles with the prefabricated foil, resulting in a bristled pad with a foil having a thickness of at least 1.5 mm, such as at least 1 mm or at least 750 μm;       

     wherein the method further comprises a body providing step in which a body of the mouthpiece to be manufactured is provided; the body providing step comprising providing a body with a recess and at least one bristle carrier; the recess having a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction and being configured for encompassing a dental arch of multiple dental positions; the at least one bristle carrier delimiting the recess; and 
     wherein the method further comprises a pad attaching step in which during or after the body providing step one or more bristled pads are attached to the at least one bristle carrier to line the bristle carrier with bristles; the back surface side of the foil facing the bristle carrier and the front surface side of the foil facing away from the bristle carrier into the recess. 
     7) Method according to one of the preceding clauses, wherein the pliable foil of the bristled pad has a bending resistance of less than 2 Newton—such as less than 1.3 Newton or less than 0.5 Newton—, the bending resistance being defined as the force F required to bend a strip of foil having a width W of 10 mm and length L of 20 mm over a distance Q of 10 mm, the force F being directed in the direction opposite to the direction in which the free ends of the bristles are facing.
 
8) Method according one of the preceding clauses, wherein the mouthpiece to be manufactured has two said recesses, the J-shaped or U-shaped length directions of both recesses extending parallel and the U-shaped cross-sections of both recesses opening in mutually opposite direction,
 
     wherein the body providing step comprises providing a body with two said recesses, the J-shaped or U-shaped length directions of both recesses extending parallel and the U-shaped cross-sections of both recesses opening in mutually opposite direction, each said recess having at least one bristle carrier delimiting the respective recess; and 
     wherein the pad attaching step comprises attaching one or more said pads to the at least one bristle carrier of each said recess. 
     9) Method according to one of the preceding clauses, wherein the bristles comprise polybutylene terephthalate (PBT) or polyamide (PA) fibers, such as nylon fibers.
 
10) Method according to one of the preceding clauses, wherein the bristles comprise fibers of a first material and wherein the bristled surface side of the foil comprises a second material fusible with the first material.
 
11) Method according to clause 10, wherein the second material is a polybutylene terephthalate (PBT) or polyamide (PA), such as nylon.
 
     12) Method according to one of the preceding clauses, wherein, in the pad attaching step, the foil of the pad is fused with the bristle carrier. 
     13) Method according to one of the preceding clauses, wherein the foil has a first outer layer configured to be fusible with the bristles and a second outer layer configured to be fusible with the bristle carrier.
 
14) Method according to one of the preceding clauses—such as according to clause 12 in combination with clause 10—, wherein the bristle carrier is of a third material not-fusible with the bristles and/or the front surface of the foil—such as not fusible with the first material and/or second material—, wherein the foil comprises a first outer layer of a material fusible with the bristles and a second outer layer of a fourth material fusible with the third material.
 
     15) Method according to clause 14, wherein the fourth material is a polypropylene (PP), a polyethylene (PE), a thermoplastic elastomer (TPE), or a thermoplastic polyurethane (TPU). 
     16) Method according to clause 14 or 15, wherein the third material is a polypropylene (PP), a polyethylene (PE), a thermoplastic elastomer (TPE), or a thermoplastic polyurethane (TPU).
 
17) Method according to one of the preceding clauses, wherein the bristle carrier comprises a polypropylene (PP), a thermoplastic elastomer (TPE), or a thermoplastic polyurethane (TPU).
 
18) Method according to one of the preceding clauses, wherein the foil is of a non-elastic material.
 
19) Method according to one of the preceding clauses, wherein the foil is of an essentially inextensible material.
 
20) Method according to one of the preceding clauses, wherein the bristle carrier is of a flexible, elastic material.
 
21) Method according to one of the preceding clauses, wherein the body further comprises at least part of a driving system configured for moving, such as reciprocatingly moving, the bristles provided in the recess with respect to the rest of the body.
 
22) Method according to one of the preceding clauses, wherein the body comprises a pressure chamber or chain of pressure chambers extending along the length of the recess, wherein the wall of the pressure chamber at the side of the recess defines the bristle carrier, wherein the pressure chamber is configured for containing a fluid under pressure; and wherein the body is configured to move the bristle carriers to and fro with respect to the recess by reciprocatingly increasing and decreasing a pressure in the pressure chamber or chain of pressure chambers between a decreased pressure condition and an increased pressure condition.
 
23) Method according to one of the preceding clauses, wherein the pad manufacturing step comprises the following steps:
 
a) providing the bristles;
 
b) providing a said prefabricated foil;
 
c) bringing the fixed ends of the bristles in contact with the foil;
 
d) heating the foil and/or fixed ends of the bristles;
 
e) fusing of the fixed ends of the bristles with the foil resulting in the bristled pad.
 
24) Method according to clause 23, wherein the heating of step d) is by means of plastic welding.
 
25) Method according to one of the clauses 23-24, wherein step d) takes place after or before step c).
 
26) Method according to one of the clauses 23-25,
 
wherein step a) comprises the steps of:
 
     providing a bristles holding tool having a foil support surface and a plurality of bores extending from the foil support surface into the tool, the bores being configured to receive bristles; and 
     inserting the bristles into the bores such that their fixed ends are at the foil support surface; 
     wherein step c) comprises placing the foil onto the foil support surface; and
 
wherein after step e) the tool is separated from the pad.
 
27) Mouthpiece obtained with the method according to one of the clauses 1-26.
 
28) Method of manufacturing a bristled pad consisting of a pliable plastic foil and plastic bristles projecting from a front surface of the foil, and the foil having a back surface opposite the front surface;
 
     wherein the method comprises the following steps: 
     a) providing bristles with a fixed end and a free end;
 
b) providing a prefabricated foil having a thickness of at most 700 μm, such as a thickness of at most 400 μm or at most 250 μm or at most 150 μm;
 
c) bringing the fixed ends of the bristles in contact with the foil;
 
d) heating the foil and/or fixed ends of the bristles;
 
e) fusing of the fixed ends of the bristles with the foil resulting in the bristled pad.
 
29) Method according to clause 28, wherein the bristled foil has a thickness of at most 1.5 mm, such as at most 1 mm or at most 750 μm.
 
30) Method according to clause 28 or 29, wherein step a) comprises the steps of:
 
     providing a bristles holding tool having a foil support surface and a plurality of bores extending from the foil support surface into the tool, the bores being configured to receive bristles; and 
     inserting the bristles into the bores such that their fixed ends are at the foil support surface; 
     wherein step c) comprises placing the foil onto the foil support surface; and
 
wherein after step e) the tool is separated from the pad.
 
31) Method according to one of the clauses 28-30, wherein the heating of step d) is by means of plastic welding.
 
32) Method according to one of the clauses 28-31, wherein step d) takes place after or before step c).
 
33) Method according to one of the clauses 28-32, wherein the pliable foil of the bristled pad has a bending resistance of less than 2 Newton—such as less than 1.3 Newton or less than 0.5 Newton—, the bending resistance being defined as the force F required to bend a strip of foil having a width W of 10 mm and length L of 20 mm over a distance Q of 10 mm, the force F being directed in the direction opposite to the direction in which the free ends of the bristles are facing.
 
34) Bristled pad obtained with the method according to one of clauses 28-33.
 
35) Mouthpiece comprising a body having a recess and at least one bristle carrier lined with bristles, the recess having a J-shaped or U-shaped length direction and an at least partly U-shaped cross-section transverse to the length direction and being configured for encompassing a dental arch of multiple dental positions, the at least one bristle carrier delimiting the recess;
 
     wherein the mouthpiece comprises one or more pads, such as one or more bristled pads obtained according to one of clauses 24-26, the pad consisting of a pliable foil and bristles projecting from a front surface of the foil; the foil having a thickness of at most 400 μm; the bristles having a fixed end fused with the foil; the foil having a back surface opposite the front surface; and 
     wherein the one or more pads are attached to the at least one bristle carrier to line the bristle carrier with bristles, the back surface side of the foil facing the bristle carrier and the front surface side of the foil facing away from the bristle carrier into the recess.
 
36) Mouthpiece according to clause 35, wherein the mouthpiece has two said recesses, the J-shaped or U-shaped length directions of both recesses extending parallel and the at least partly U-shaped cross-sections of both recesses opening in mutually opposite direction.
 
37) Mouthpiece according to clause 35 or 36, wherein the body comprises a pressure chamber or chain of pressure chambers extending along the length of the recess, wherein the wall of the pressure chamber at the side of the recess defines the bristle carrier, wherein the pressure chamber is configured for containing a fluid under pressure; and wherein the body is configured to move the bristle carriers to and fro with respect to the recess by reciprocatingly increasing and decreasing a pressure in the pressure chamber or chain of pressure chambers between a decreased pressure condition and an increased pressure condition.
 
38) Dental cleaning device comprising a mouthpiece according to clause 37 and a pressure and/or suction device which is configured to be in fluid communication with the pressure chamber or chain of pressure chambers and configured for reciprocatingly increasing and decreasing the pressure in the pressure chamber.