WO2001012100A1

WO2001012100A1 - Dental floss device

Info

Publication number: WO2001012100A1
Application number: PCT/GB2000/002906
Authority: WO
Inventors: Jacob Moses Blass
Original assignee: Westone Products Limited
Priority date: 1999-08-18
Filing date: 2000-07-28
Publication date: 2001-02-22
Also published as: TW504379B; AR025241A1; AU6299200A; GB9919574D0

Abstract

A dental floss device has a length (7) of dental floss which comprises a plurality of threads organised in an interlaced array and a frame member (3, 4) carrying the length of dental floss. The length of dental floss is anchored, at at least one end, to the frame member by mechanical interlocking of material of said frame member with said threads. At least one of the threads of the floss is a thread of PTFE. One or more threads of other material may be included. The floss may be a braided product.

Description

DENTAL FLOSS DEVICE

FIELD OF THE INVENTION

This invention relates to dental floss devices, in particular hand-held devices which have a frame member carrying a length of dental floss. Such devices facilitate the insertion of the dental floss into interdental spaces and the action of cleaning teeth by moving the floss in the interdental spaces. The term dental floss as used in this specification includes material of any suitable cross section, for example, of a tape shape .

DESCRIPTION OF THE PRIOR ART Known dental floss devices on the market include a handle and a frame portion attached to the handle and of a generally C- shape, with a length of dental floss stretched across the ends of the frame portion and anchored in those ends, for example, by moulding the ends of the frame portion around the ends of the floss. Some such devices are commonly known as "floss-picks" because the handle may also double as a tooth pick.

US-A-4998978 describes the use of a flat flexible strip, which may be made of woven strands or strands arranged in a haphazard pressed pattern, for tooth cleaning. The crossed strands produce a frictional scrubbing engagement with the teeth.

EP-A-764431 describes a braided dental floss formed of a plurality of threads, each of which is at least one strand of nylon, polyester, polyethylene, PTFE, PFA or polypropylene or mixtures thereof .

Recently there have been developed dental flosses based on PTFE, which have considerable advantages in use.

See EP-A-335466 (Colgate) and WO 92/10978 (Westone) and WO 96/10478 (Westone) . The anchoring of a length of PTFE floss is more difficult than of conventional flosses based on nylon or ultra high density polyethylene, because of the difficulty of achieving a strong bond to PTFE.

SUMMARY OF THE INVENTION

An object of the invention is to provide a dental floss device using PTFE floss, in which the PTFE floss is strongly anchored, which can be produced at low cost. According to a first aspect of the present invention there is provided a dental floss device having a length of dental floss which comprises a plurality of threads organised in an interlaced array and a frame member carrying said length of dental floss, said length of dental floss being anchored, at at least one end thereof, to said frame member by mechanical interlocking of material of said frame member with said threads, wherein at least one of said threads is a thread of PTFE.

Preferably both ends of the length of floss are anchored in this manner. Preferably the mechanical interlocking is achieved by in situ moulding (insert moulding) . Typically the frame member has the length of floss extending across an open portion of the frame member and anchored to the frame member at its respective ends . By the term "interlaced" is meant the organisation of threads such that a structured thread array is provided having an identifiable repeat unit caused by the crossing over and interlinking of individual threads. The term therefore encompasses the structures produced by repetitive interweaving processes e.g. woven, knitted, braided, plaited, crocheted, knotted or laced structures, but excludes structures produced without interweaving e.g. mere twisting of a plurality of threads, which structures do not provide a sufficiently rough surface. The dental floss therefore presents a plurality of cleaning edges on its outer surface. By a cleaning edge is meant a projecting or partially projecting thread portion which is running at least partially transversely around the floss. Such thread portions are held in place by the interlaced structure of this floss. In other words the floss has a structural surface roughness. An advantage of the interlaced array structure is that when tension is applied to the floss it retains its bulkiness and the cleaning edges continue to be presented on its outer surface. Therefore, not only does the floss provide an enhanced cleaning action, but also at the anchors the threads are not encouraged to disengage from the frame member, thereby helping to prevent the floss from being pulled free of the frame member. In other words mechanical keying of the floss to the member is promoted.

The threads may be of various cross-sectional shape e.g. circular, oval, rectangular or irregular, or composed themselves of a plurality of e.g. interlaced, entwined or twisted filaments. Preferably, the frame member is formed by injection moulding, the moulding material being e.g. suitable plastics material such as polypropylene. Preferably the moulding of the frame member is performed with the floss length in situ. That is to say, during moulding the length of floss is held in place and the moulding material flows around and between the threads of the floss to key the floss in place.

In order for the interlaced array of threads to present an acceptable cross-sectional area (i.e. one that can be inserted into interdental spaces) , the individual threads are preferably less bulky than comparable unitary strand dental floss. For example conventional dental floss comprising a single PTFE tape typically has a decitex (dtex) of in the range 800-2400, more typically about 1000. For comparison, the interlaced array may comprise e.g. two threads of 400 dtex, or four threads of 60 dtex. The preferred overall dtex of the interlaced array is 600 to 1200, and more preferred is about 800 dtex or less.

Preferably within the invention, all of the fibre threads of the dental floss may be PTFE strands.

However, in one form of the invention, at least one of the threads is a thread of a fibre material which is not PTFE. The or each thread of material which is not PTFE may for example be made of a material which is any one of nylon, polyester, polypropylene and polyethylene, and preferably each such thread is a multi- filament thread. Preferably the number of threads of PTFE is at least equal to the number of threads which are not of PTFE, and more preferably the number of threads of PTFE is greater than the number of threads which are not of PTFE.

Preferably the weight of PTFE in the dental floss is at least 50%.

Use of threads of two different materials in the dental floss device of the invention can provide several advantages. The second material, which is not PTFE, can provide bonding strength at the interlocking of the dental floss with the material of the frame member, for example when the frame member is formed by in situ molding. There may be adhesive bonding between the material of the frame member and a fibre material such as nylon. The anchoring strength of the dental floss in the frame member is thus increased.

As is known, a thread of a fibre such as nylon, polyester, polypropylene or polyethylene, is typically formed as a multi-filament , for example having 10 to 150 filaments in the case of nylon. In use in dental floss, such a thread has the disadvantage that, if the strand breaks, it tends to shred giving discomfort. However, in the interlaced fibre array of the dental floss used in the present invention, the broken end of a thread is held in place, so that the tendency for it to splay out is much reduced.

Furthermore, the thread or threads which are not of PTFE can provide tensile strength in the material, since such threads are typically non-extensible or relatively inextensible. However, the advantages of PTFE in dental floss, such as its low coefficient of friction, are not lost. As mentioned above, the dental floss used in the present invention is effective in cleaning because of the cleaning edges at its outer surface. These edges give a good feel for the user, in use of the device, but the dental floss is not abrasive, i.e. does not tend to damage the teeth.

Another advantage of the use of a second fibre material is to reduce the cost, since PTFE is relatively expensive.

The examples of dental floss which can be used in the invention are : - a four thread floss consisting of two PTFE threads and two nylon threads, a four thread floss consisting of three PTFE threads and one nylon thread, an eight thread floss consisting of six PTFE threads and two nylon threads .

The threads typically have all the same weight per unit length (dtex) . An 800 dtex thread may be formed by three threads of 200 dtex PTFE and one thread of 200 dtex nylon, or from one thread of 400 dtex PTFE and one thread of 400 dtex nylon.

Each PTFE thread is typically a single PTFE filament, which may be incorporated in flat or twisted form. The thread of a synthetic polymeric material such as nylon, polyester, polypropylene, or polyethylene is typically of round cross-section, being a plurality of filaments (strands) twisted together. The dental floss, formed as the interlaced array, may be itself round or flat. As mentioned above, a relatively inextensible thread which is not PTFE controls the extensibility of the dental floss . The PTFE thread or threads may therefore be of more extensible material, i.e. relatively weak PTFE which is of lower cost.

According to the invention in a second aspect there is provided a dental floss device having a length of dental floss comprising at least one PTFE thread and a frame member carrying said length of dental floss, said length of dental floss having, at at least one end thereof, an anchoring body of material selected from hardened adhesive and hardened synthetic resin bonded to it, said anchoring body engaging with an abutment surface of said frame member in order to anchor said length of dental floss to said frame member.

Preferably in the second aspect the frame member is moulded (e.g. of suitable plastics material such as polypropylene) , the floss being held in position during the moulding process . The abutment surface of the frame structure can then be formed in situ by allowing the moulding material to flow around and conform to the shape of the anchoring body. More preferably the anchoring body is incorporated into the frame structure so that it is essentially hidden from view. However, the abutment surface of the frame structure may be any surface which can resist tension in the floss by anchoring the anchoring body, e.g. an outward- facing arm surface of a C- shaped frame structure.

The adhesive or resin of the anchoring body is any suitable substance which forms a bond with the PTFE thread strong enough to prevent the thread detaching from the anchoring body. The bonding of the anchoring body to the PTFE strand may be mechanical and/or chemical. Preferred substances are cyano-acrylate adhesive and epoxy resin which, it is believed, form chemical bonds to the PTFE, thereby providing good bond strengths. More preferably the adhesive or resin is UV curable so that heat curing, which may degrade the PTFE, can be avoided. The bonding of the adhesive or resin to the PTFE may be promoted by priming the corresponding portion of the PTFE strand with a primer before the adhesive or resin is applied.

The floss length of the device in both aspects of the invention may be coated with for example wax or wax containing adjuvants, or may be uncoated. A particular advantage of the use of an unwaxed floss is that it can be used many times, and simply washed and dried between each use. A waxed floss is less suitable for re-use, since it is changed by removal of the wax in use, and also tends to collect debris from the user's mouth, which cannot be easily washed off. The term PTFE is here used, as is usual, to describe a member of a range of polymers based on polytetrafluoroethylene . For example, as is conventional, small amounts of co-monomers may be included, such as ethylene, chlorotrifluoroethylene or hexafluoropropylene, provided that the properties of the product are satisfactory.

Conventionally, PTFE is extruded with a lubricant, which is subsequently removed, for example, by heat cleaning or solvent extraction. The PTFE may, as is conventional, include one or more fillers and/or pigments. For dental floss at least, unfilled PTFE is preferred.

The device of the first aspect of the invention may be combined with the device of the second aspect, i.e. the floss of the device may comprise a plurality of PTFE filaments organised in an interlaced array with an enlargement of cured or hardened adhesive or resin at at least one of the ends of the floss. BRIEF INTRODUCTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of non-limitative example, with reference to the accompanying drawings in which:- Fig. 1 diagrammatically illustrates a cross-section through a first embodiment of the invention,

Fig. 2 diagrammatically illustrates a continuous length of PTFE dental floss,

Fig. 3 diagrammatically illustrates a cross-section through a second embodiment of the invention,

Fig. 4 diagrammatically illustrates a cross-section through a third embodiment of the invention, and

Fig. 5 illustrates the construction of a braid.

DESCRIPTION OF THE EMBODIMENTS

The floss device of Fig. 1 comprises a handle 1 and a C- shaped frame 2 integral with the handle, these two parts being injection moulded as a single piece from a suitable synthetic plastics material such as polypropylene. The C-shaped frame has two arms 3 and 4 projecting to free ends. A length 5 of dental floss, which may be waxed or unwaxed, extends between the extremities of the two arms.

As discussed above, this dental floss may be a single strand of PTFE, e.g. one manufactured in accordance with WO 96/10487 (Westone) , or a plurality of such strands twisted together.

Each end of the length of floss carries an anchoring body or enlargement in the form of a bead of hardened cyano-acrylate adhesive. The floss device is moulded with the length of floss held in position so that the beads of adhesive are embedded into the arms of the frame and are hidden from view.

In use, the floss may be under tension when it is moved in the interdental spaces, but the floss is prevented from being pulled free of arms 3 and 4 because the material of arms 3 and 4 which abuts the beads 6 stops the beads from moving and the floss in turn remains securely bonded to the beads .

Fig. 2 diagrammatically illustrates a continuous length of PTFE dental floss suitable for use in the mass production of floss devices. The adhesive is applied along the length in spaced apart beads 6. Therefore it is possible to in situ mould simultaneously a plurality of devices side-by-side, the continuous length thereafter being cut into shorter lengths to separate the devices.

Fig. 3 shows an alternative embodiment of the floss device in which the beads 6 are located at outward- facing faces of arms 3 and 4. In this embodiment the enlargements formed by the beads are restrained by abutting outward- facing surfaces of arms 3 and 4 rather than internally conforming surfaces, but essentially the length of floss 5 is restrained in the same manner as in the first embodiment.

Fig. 4 shows a schematic cross -section through a third embodiment of the invention. This embodiment also comprises a moulded plastics C- shaped frame 2 with arms 3 and 4 and a handle 1. However, instead of a single- strand PTFE dental floss a braided length 7 of floss is used, the floss comprising a plurality of (schematically illustrated) interlaced PTFE strands 8 each being a single filament made according to WO 96/10478, for example four filaments each of 200 dtex. The frame is moulded with the length 7 held in position extending between the extremities of arms 3 and 4. During moulding the plastics material of the frame infiltrates around and between the threads of the braided floss so that interlocking surfaces 9 (shown schematically) are formed which mechanically key to the braided floss and prevent it from working free of the frame when the floss is under tension.

Like the devices shown in Figs. 1 and 3 this device can also be mass produced in batches from a continuous length of braided floss.

As discussed above, the braided floss 7 of Fig. 4 may be composed of one or more PTFE threads and one or more threads of another material. Details of materials are given above .

Fig. 5 illustrates the construction of a braid, formed in this case of eight strands. The numbers alongside the sketch indicate the repetition pattern along the length of the braid. Such a braid is applicable in the invention, and is schematically illustrated in Fig. 4, where however the braid is formed of four threads only. In Fig. 4, the transverse dimension of the braided floss is greatly exaggerated. Although the invention has been described above in relation to particular embodiments, many variations are possible within the spirit and scope of the invention herein described, as will be clear to an expert.

Claims

1. A dental floss device having a length (7) of dental floss which comprises a plurality of threads (8) organised in an interlaced array and a frame member (2) carrying said length of dental floss, said length of dental floss being anchored, at at least one end thereof, to said frame member by mechanical interlocking of material of said frame member with said threads, wherein at least one of said threads is a thread of PTFE.

2. A dental floss device according to claim 1, wherein said frame member has two spaced portions (3, 4) opposed to each other across a gap, said length (7) of dental floss extending across said gap and being anchored at its respective ends in said two spaced portions of said frame member by said mechanical interlocking.

3. A dental floss device according to claim 1 or 2, wherein said mechanical interlocking is obtained by in situ moulding of said material of said frame member (2) around said length (7) of dental floss.

4. A dental floss device according to claim 1, wherein said interlaced array is one obtained by a repetitive interweaving process.

5. A dental floss device according to claim 4, wherein said repetitive interweaving process is weaving, knitting, braiding, plaiting, crocheted, knotting or lacing.

6. A dental floss device according to any one of claims 1 to 5 , wherein at least one of said threads is a thread of a second material which is not PTFE.

7. A dental floss device according to claim 6, wherein the number of said threads which are of PTFE is at least equal to the number of said threads which are not of PTFE.

8. A dental floss device according to claim 6 or 7 , wherein said length of dental floss is by weight at least 50% of PTFE.

9. A dental floss according to any one of claims 1 to 5, wherein all of said fibre threads are PTFE.

10. A dental floss device having a length of dental floss comprising at least one PTFE thread and a frame member carrying said length of dental floss, said length of dental floss having, at at least one end thereof, an anchoring body of material selected from hardened adhesive and hardened synthetic resin bonded to it, said anchoring body engaging with an abutment surface of said frame member in order to anchor said length of dental floss to said frame member.

11. A dental floss device according to claim 10, wherein said frame member is formed by in situ molding whereby said abutment surface thereof is formed by molding against said anchoring body.

12. A dental floss device according to claim 10 or 11, wherein said anchoring body is substantially hidden within the material of said frame member.