GB2526689A

GB2526689A - Oral hygiene device

Info

Publication number: GB2526689A
Application number: GB1507450.3A
Authority: GB
Inventors: Eleanor Farrant
Original assignee: Wisdom Toothbrushes Ltd
Current assignee: Wisdom Toothbrushes Ltd
Priority date: 2014-04-30
Filing date: 2015-04-30
Publication date: 2015-12-02
Anticipated expiration: 2035-04-30
Also published as: GB2526689B; GB201507450D0; GB2525638A; GB201407632D0

Abstract

An oral hygiene device, or toothbrush 1 with a cleaning element 30, comprises silica granules and plastic in a ration of less than 70:30 by mass. The toothbrush 1 comprises a handle 10 and a head 20 which comprises upstanding elements 33 and bristles set in apertures 41. The cleaning element 30 also includes a polishing pad (35, figure 1) having a region of arcuate ribs (36, figure 1) and an undulating surface 37. The application includes a method of manufacturing such an oral hygiene device with a cleaning element by mixing granules of a carrier plastic with granules of silica to form a first mixture and then extruding the carrier mixture under heat and pressure to produce the device. It also includes a method of manufacture in which the first mixture is extruded to produce pellets which are then used to mould an abrasive cleaning element by injection moulding.

Description

Oral Hygiene Device The invention relates to an oral hygiene device comprising tooth cleaning and/or polishing functionality and a method of manufacture thereof.

It is known to provide an oral hygiene device with elements intended to provide tooth cleaning and/or polishing functionality, distinct from or combined with a conventional bristle-based toothbrush.

The oral hygiene device of the present invention involves a simple manufacturing method, combined with a high degree of stain removal and a low degree of tooth abrasion.

Against this background, there is provided an oral hygiene device comprising a cleaning element, the cleaning element comprising a plastic and silica granules, wherein a ratio of silica to plastic by mass is less than 70:30.

Advantageously, the ratio of silica to plastic has been shown to result in a high degree of stain removal and a low degree of tooth abrasion.

Preferably, the silica granules are distributed substantially evenly through the plastic.

Advantageously, this means that the cleaning element of silica and plastic can be co-extruded from a single homogenous stock.

Preferably, a majority (meaning more than 50 %) of the silica granules are between 2 pm and 15 pm in diameter.

In a further aspect of the invention there is provided a method of manufacturing an oral hygiene device with a cleaning element, the method comprising the following steps, in order: (a) mixing granules of a carrier plastic with granules of silica to form a first mixture; (b) extruding the carrier mixture under heat and pressure to produce pellets of a homogenous stock comprising the carrier plastic with the granules of silica distributed within; and (c) injection moulding an output of the previous step into a mould to form the abrasive cleaning element.

Preferably, the method further comprises, between step (b) and step (c), the steps of: (b') mixing granules of a second plastic to the pellets of homogenous stock to form a second mixture; and (b') extruding the second mixture under heat and pressure to produce a further homogenous stock comprising: the carrier plastic; the second plastic; and the silica distributed within.

Advantageously, this allows the carrier plastic to be of a different hardness to the second plastic.

Embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a part of a toothbrush comprising a cleaning element in accordance with an embodiment of the invention; Figure 2 shows a part of the toothbrush of Figure 1 from an opposite perspective; Figure 3 shows a pad of the toothbrush of Figures 1 and 2 from a further perspective; Figure 4 shows an oral hygiene device in accordance with a second embodiment of the invention; Figure 5 shows the oral hygiene device of Figure 4 from a further perspective; Figure 6 shows an oral hygiene device in accordance with a third embodiment of the invention; Figure 7 shows the oral hygiene device of Figure 6 from a further perspective; Figure 8 shows a pad of an oral hygiene device in accordance with a fourth embodiment of the invention; Figure 9 shows a part of an oral hygiene device in accordance with a fifth embodiment of the invention; Figure 10 shows a pad of an oral hygiene device in accordance with a sixth embodiment of the invention; Figure 11 shows a pad of an oral hygiene device in accordance with a seventh embodiment of the invention; and Figure 12 shows a part of an oral hygiene device in accordance with an eighth embodiment of the invention.

Figures 1 to 3 show a part of an oral hygiene device, in this case a toothbrush 1, comprising a cleaning element in accordance with an embodiment of the invention. The toothbrush 1 comprises a handle 10 and a head 20. The head 20 comprises a cleaning element 30 and apertures 41 for receiving one or more bristles (not shown). The bristles

may be conventional in the field of toothbrushes.

The cleaning element 30 in this embodiment comprises upstanding elements 33 that project substantially perpendicularly from a plane of the head 20 and parallel to the apertures 41 for receiving bristles. The cleaning element 30 further comprises a polishing pad 35 having a region comprising arcuate ribs 36 and a region comprising an undulating surface 37. The cleaning element 30 is formed of a single moulded component that extends through apertures (not visible in the Figures) in the head 20 between the upstanding elements 33 and the polishing pad 35.

Bristles (not shown) may be mounted in the apertures 41 to extend in an upstanding manner parallel to the upstanding elements 33 of the cleaning element 30. The bristles may extend to the same height, relative to the head 20, as the upstanding elements 33.

When used for polishing teeth, the upstanding elements 33 of the cleaning element 30 may contact the teeth during conventional brushing of the teeth using the interspersed bristles (not shown). Also in use, the arcuate ribs 36 and the undulating surface 37 may be used to polish the teeth in the absence of conventional brushing. They may be used particularly for removal of a specific tooth stain.

In alternative embodiments to that of Figures 1 to 3 there may be only a subset of the features of the cleaning element 30. For example, there may be only the upstanding elements 33 and not the polishing pad 35. Alternatively, there may be only the polishing pad 35 and not the upstanding elements 33. In the event that there is a polishing pad 35, it may comprise only one of the two regions (36, 37) or a differently profiled region altogether (not shown) useful for polishing a tooth or teeth.

The handle 10 may be of a first material, preferably a plastic, having a first hardness. The cleaning element 30 may be of a second material having a second hardness. The second material may comprise a plastic that has distributed within it, preferably substantially evenly, a number of silica granules. The first material plastic may be harder than the second material plastic. The silica may be harder than both of the plastics. The first plastic may be a thermoplastic or a thermoset. The second plastic may be a thermoplastic or a thermoset.

Since the nature of the materials and their production is not specific to the first embodiment, more detail regarding the material properties and manufacture is provided later in the description, after the description of other preferred embodiments of oral hygiene device in accordance with the present invention.

Figures 4 and 5 show a second embodiment of an oral hygiene device 200 in accordance with the invention. In this embodiment, there are no bristles for conventional tooth-brushing. Instead, this embodiment is intended as a tongue cleaner 200.

The tongue cleaner 200 comprises a handle 210 and a head 220. The head 220 is in the form of a substantially oval loop so as to provide a range of radii portions suitable for cleaning the tongue. The substantially oval loop comprises a cleaning element 230 for manoeuvring over the tongue to remove bacteria.

Figures 6 and 7 show a third embodiment of an oral hygiene device 300 in accordance with the invention. In this embodiment, there are no bristles for conventional tooth-brushing.

Instead, this embodiment is intended as a dedicated tooth polisher 300.

The tooth polisher 300 comprises a handle 310 and a head 320. The head 320 is in the form of a substantially frustoconical root and a substantially conical tip comprising a cleaning element 330 for polishing teeth. As shown, the substantially conical tip is slightly domed so as to provide a range of radii portions suitable for reaching a variety of spaces within the mouth, including, perhaps, some interdental spaces.

Figure 8 shows a fourth embodiment of an oral hygiene device 400 in accordance with the invention. In this embodiment, there are no bristles for conventional tooth-brushing.

Instead, this embodiment is intended as an interdental cleaning device 400 to clean and polish, especially between the teeth.

The interdental cleaning device 400 comprises a handle 410 and a head 420. The head 420 is in the form of a substantially conical trunk and further substantially conical branches 430. The substantially conical branches 430 may each have an elongate axis that is substantially perpendicular to an elongate axis of the substantially conical trunk. The substantially conical branches 430 reduce in size with distance from the handle 410. Each substantially conical branch 430 and the substantially conical trunk may be used as a tooth polishing element. The variety of sizes and positions of the tooth polishing trunk and branches provides for a range of different geometrical elements having different radii and therefore providing a range of options suitable for reaching a variety of spaces within the mouth, including interdental spaces.

The wider end of the conical head 420 is proximate the handle 410 and the narrower end is distal relative to the handle. An average diameter of at least some of the branches 430 located at or towards the distal end is less than an average diameter of at least some of the branches 430 located at or towards the proximal end.

Figure 9 shows a fifth embodiment of an oral hygiene device 500 in accordance with the invention.

This embodiment is similar to that of Figures ito 3 in that it more closely resembles a conventional toothbrush than the embodiments of Figures 4 to 8.

The oral hygiene device 500 comprises a handle 510 and a head 520. The head 520 comprises a cleaning element 530 comprising upstanding elements 530 that are located at the edges of the head 520. The upstanding elements 530 project substantially perpendicularly from a top surface of the head 520. The upstanding elements may be substantially planar and of approximately uniform thickness, as shown in Figure 9, and may have a profile resembling a half-wavelength sinusoidal curve, at least in a portion that projects above the top surface of the head 520. In the illustrated embodiment, there are three such upstanding elements on each of two sides of the head 520. Other numbers, locations and arrangements of upstanding elements are included within the scope of the

disclosure.

The head 520 may or may not comprise apertures (not shown) for mounting bristles (also not shown) to project from the top surface of the head (or the bottom surface of the head) in a direction substantially parallel with the upstanding elements 530.

Figure 10 shows a sixth embodiment of an oral hygiene device 600 in accordance with the invention.

The oral hygiene device 600 comprises a handle 610 and a head 620. The head 620 comprises a cleaning element 630 comprising an upstanding element 630 that projects from a central portion of a top surface of the head 620. The cleaning element 630 is of approximately uniform thickness. Cross-sectional planes through the cleaning element 630 parallel to the top surface of the head 620 may be substantially consistent in shape and dimensions. The shape of the cleaning element 630, when viewed in cross-section parallel to the top surface of the head 620, may resemble a sinusoidal wave. In particular, in the illustrated example of this embodiment (Figure 10), the sinusoidal wave shape may project for approximately 11⁄2 wavelengths. Variations on the shape, length and number of the upstanding element(s) are included within the scope of the disclosure.

The head 620 may or may not comprise apertures (not shown) for mounting bristles (also not shown) to project from the top surface or the bottom surface of the head in a direction substantially parallel with the upstanding elements 630.

Figure 11 shows a seventh embodiment of an oral hygiene device 700 in accordance with the invention.

The oral hygiene device 700 comprises a handle 710 and a head 720. The head 720 comprises a cleaning element 730 comprising a plurality of upstanding elements that project from a top surface of the head 720 substantially perpendicularly therefrom. Each upstanding element is in the form of an elongate projection that may be consistent in cross sectional shape and size along its length.

The head 720 may or may not comprise apertures (not shown) for mounting bristles (also not shown) to project from the top surface or the bottom surface of the head in a direction substantially parallel with the upstanding elements 730.

Figure 12 shows an eighth embodiment of an oral hygiene device 800 in accordance with the invention.

The oral hygiene device 800 comprises a handle 810 and a head 820. The head 820 comprises a cleaning element 830 comprising a planar upstanding element that projects from a top surface of the head 820 substantially perpendicularly therefrom. The upstanding element is in the form of a rectangular projection.

The head 820 may or may not comprise apertures (not shown) for mounting bristles (also not shown) to project from the top surface or the bottom surface of the head in a direction substantially parallel with the upstanding elements 830.

Any of the embodiments, and particularly the fourth, fifth, sixth, seventh and eighth embodiments that resemble more closely a conventional toothbrush in overall form, may further comprise additional polishing elements such as, but not limited to, the arcuate ribs 36 and the undulating surface 37 shown in the first embodiment in Figures ito 3.

Having described various embodiments of the invention and focused so far on the geometry of the oral hygiene devices that fall within the scope of the invention, the following description relates to the material properties falling within the scope of the invention and a method of manufacture.

In the embodiments described above, the handle and head of the oral hygiene devices is of a first material having a first hardness. The cleaning element, on the other hand, is of a second material having a second hardness.

The first material, used for the handle and head, may be a thermoplastic, such as polypropylene. The first material may be injected into a first mould having an internal three-dimensional shape corresponding to the external shape of the handle and head of the oral hygiene device. The first mould may comprise one or more protrusions that are intended to result in one or more cavities and/or apertures in the head of the oral hygiene device. The one or more cavities and/or apertures may be configured for receiving the second material, as described in more detail below.

The second material, used for the cleaning elements, comprises a plastic that includes silica granules. The plastic may be a thermoplastic or a thermoset. The plastic may, for example, be a thermoplastic elastomer, thermoset elastomer, polyethylene, polypropylene, silicone, rubber, polysiloxanes, ethylene propylene diene monomer rubber, neoprene, polychloroprene, fluoroelastomer, natural rubber, latex, butyl rubber, nitrile rubber, styrene butyle rubber, polyester, polyurethane, blends of thermoset rubbers and elastomers, sponge rubbers and their blends or any appropriate combination of the above.

When using a thermoset derived from two parts, one part may be a curing agent that may be in liquid gel or semi-solid form. The curing agent may be a solvent, water or emulsion, suspension, colloid, condensate or any carrier system dispersant for the catalyst. When using a thermoset, the setting (curing, cross-linking, vulcanisation) may be achieved using cold curing, ultra-violet curing, heat catalysing, condensation systems or any other appropriate technique.

In the event that the second material comprises a thermoplastic, the second material may be produced using the following procedure. Crushed and filtered silica of the chosen dimensions may be mixed with granules of a thermoplastic carrier (such as polyethylene) to an appropriate first ratio of mixture.

Using a first Archimedean screw under heat and pressure, the mixture of granules of thermoplastic carrier and silica is compressed to form a homogenous material of thermoplastic carrier with silica embedded therein, preferably substantially evenly. The material is extruded from the first Archimedean screw and cut into pellets, hereinafter referred to as a first set of pellets.

Subsequently, the first set of pellets is mixed with a second set of pellets, the second set of pellets being of a thermoplastic elastomer. A ratio of first pellets to second pellets is chosen in accordance with a desired overall ratio of silica granules to plastic (e.g. both thermoplastic carrier and thermoplastic elastomer).

Using a second Archimedean screw under heat and pressure, the mixture of first and second sets of pellets is compressed to form a homogenous material of thermoplastic carrier, thermoplastic elastomer and silica, wherein the silica is preferably substantially evenly distributed within the combined plastic material. The combined plastic material is extruded from the second Archimedean screw to form the cleaning element of the oral hygiene device.

The handle and head of the oral hygiene device, having been produced from the first material in accordance with the method described above, is, once cooled and sufficiently hard, transferred or repositioned from the first mould in which it is produced, into a second mould or cavity that accommodates the handle and head and provides a further associated cavity into which the second material may be injected at the appropriate location relative to the head to form the cleaning element.

In the case of the first embodiment oral hygiene device 1, for example, the second mould may comprise a cavity having a first portion that accommodates the already-formed handle and head 20, and a second portion that corresponds to the shape (and relative position) of the cleaning element 30. The head 20 of the first oral hygiene device 1 comprises apertures in the head 20 that extend from a top surface of the head to a bottom surface of the head and enable the extruded second material to fill the cavity to form contiguous portion of the second material. The contiguous portion of the second material comprises the upstanding elements 33 as well as the arcuate ribs 36 and the undulating surface 37 and includes an intermediate portion that extends between and joins the upstanding elements 33 (on the top side of the head) and the arcuate ribs 36 and undulating surface 37 (on the bottom side of the head).

In the event that the second material comprises a thermoset, the second material may be produced using the following procedure. A pre-cured thermosetting polymer (which may be in liquid, gel, paste or powder form) may be mixed with crushed and filtered silica of the chosen dimensions to an appropriate first ratio of mixture.

The handle and head of the oral hygiene device may be produced as described above and the second material may be moulded around it in the second cavity or mould. Immediately prior to injecting the thermoset mixed with silica into the second mould or cavity, the thermosetting polymer mixed with silica is combined with a curing agent to prompt cross-linking of constituents of the thermosetting polymer. Heat and or ultra-violet radiation is applied to the combination of materials in the second mould or cavity such that cross-linking occurs and the thermoset hardens (with the silica embedded) to form the cleaning elements of the appropriate form.

Alternatively, instead of mixing with the thermosetting polymer, the crushed and filtered silica of the chosen dimensions may be mixed with the curing agent. Then, immediately prior to injecting thermosetting polymer into the second mould, the thermosetting polymer is combined with the mixture of silica and curing agent.

The curing agent may, for example, be a liquid comprising platinum, tin or peroxide. Where present, platinum or tin may be in suspension.

In one embodiment, the second material may be derived from liquid silicon rubber cured using a platinum-containing curing agent at temperature above ambient.

In some variations of the above described embodiments, additional ingredients may be included in the second material. For example, the silica granules may be combined with other additives such as flavour, fragrance, colourant and chemical cleaning aids. One example of such would be cetylpyridinium chloride (CRC). Other flavours, fragrances and chemical cleaning aids may be included in addition or by way of alternative. The second material may further include other additives such as micro-silver as an antibacterial agent.

While the embodiment described above wherein the second material comprises a thermoplastic makes use of a two-stage process (comprising first combining granules of thermoplastic carrier and silica in a first extrusion process and subsequently combining the result of the first extrusion process with a second set of thermoplastic pellets), it is possible to achieve the combination of all three materials by performing only a single extrusion process using only one Archimedean screw. In a further alternative, it may be that silica is mixed with only one thermoplastic material in the said single extrusion process.

A further alternative would be to extrude the cleaning element directly rather than extruding to pellets and injecting moulding.

While manufacturing processes have been described for an embodiment where the first material is a thermoplastic and the second material is either a thermoplastic or a thermoset, other embodiments fall within the scope of the disclosure including those wherein the first material is a thermoset. Where the first material is a thermoset, thermosetting processing techniques such as those described above in respect of a thermoset second material may be adopted.

Various materials are mentioned herein. In one embodiment, silica is embedded in thermoplastic while in another embodiment silica is embedded in thermoset. The differences in manufacture as between these two possibilities have also been described.

Alternative thermoplastic materials that may be employed include polypropylene, high density polyethylene, linear low density polyethylene, styrenic based nylons, or any other thermoplastic. Alternative thermosets that may be employed include silicone (silicone rubber) and polyurethane. Whether using a thermoplastic or a thermoset, it is required that the cleaning element comprises a carrier for silica granules that are distributed homogenously and substantially evenly throughout the cleaning element (rather than being present only at the surface or on top of the surface of the plastic).

It has been found that the ratio of plastic carrier to silica is important in achieving effective cleaning and appropriately minimal tooth abrasion. A minimum ratio by mass of silica to plastic for effective cleaning has been found to be 10:90. A maximum ratio by mass of silica to plastic for acceptable tooth abrasion characteristics has been found to be 70:30. A preferred ratio that represents a preferred characteristic of cleaning and abrasion has been found to be 15:85.

Furthermore, it has been found that a distribution of granule diameters wherein 90 % of the granules have a diameter of between 2 and 710 pm is preferable, and a distribution of granule diameters wherein 90 % of the granules have a diameter of between 2 and 60 pm is more preferable. Still more preferable is a distribution of granule diameters wherein % of the granules have a diameter of less than 5 to 8 pm. More preferable is a distribution of granule diameters wherein 80% of granules have a diameter of less than 3.95 to 6 pm. Even more preferable is a distribution of granule diameters wherein 50 % of granules have a diameter of less than 3 to 5 pm.

A preferred diameter of silica granule has been found to be between 2 pm and 15 pm. This is not to say that every single granule must be within this range of diameters. Rather, it is to say that the majority of granules (between 50 % and 90 %) fall within this range of diameters.

Claims

CLAIMS: 1. An oral hygiene device comprising a cleaning element, the cleaning element comprising a plastic and silica granules, wherein a ratio of silica to plastic by mass is less than 70:30.
2. The oral hygiene device of claim 1 wherein the silica granules are distributed substantially evenly through the plastic.
3. The oral hygiene device of claim 1 or claim 2 wherein the ratio of silica to plastic by mass is between 10:90 and 20:80.
4. The oral hygiene device of claim 3 wherein the ratio of silica to plastic by mass is 15:85.
5. The oral hygiene device of any preceding claim wherein the plastic comprises a thermoplastic elastomer.
6. The oral hygiene device of any preceding claim wherein the plastic comprises a thermosetting plastic.
7. The oral hygiene device of claim 6 wherein the thermosetting plastic comprises silicone.
8. The oral hygiene device of any of claims 5 to 7 wherein the plastic further comprises polyethylene.
9. The oral hygiene device of any preceding claim wherein a majority of the silica granules are between 2 pm and 15 pm in diameter.
10. The oral hygiene device of claim 8 wherein 90 % of the silica granules are between 2 pm and 15 pm in diameter.
11. The oral hygiene device of any preceding claim wherein a maximum diameter of silica granules is 15 pm.
12. The oral hygiene device of any preceding claim further comprising a head having a first face and a plurality of bristles projecting from the first face, wherein the cleaning element projects from the first face and is interspersed with the bristles.
13. The oral hygiene device of claim 12 comprising a plurality of cleaning elements interspersed with the bristles.
14. The oral hygiene device of claim 12 or claim 13 wherein the cleaning element also comprises a polishing element on a second face of the head opposite the first face.
15. The oral hygiene device of claim 14 wherein the cleaning element comprises a singly moulded component comprising a joining part that extends between the first face and the second face.
16. The oral hygiene device of any preceding claim wherein the cleaning element comprises an elongate body having an elongate axis and a plurality of longitudinal branches each having a longitudinal axis, wherein an longitudinal axis of at least one of the branches is perpendicular to the elongate axis.
17. The oral hygiene device of claim 16 wherein the body is substantially frustoconical or conical.
18. The oral hygiene device of claim 16 or claim 17 wherein, for at least a subset of the plurality of branches, each branch is substantially frustoconical or conical.
19. The oral hygiene device of any of claims 16 to 18 further comprising a handle such that a wider end of the body is proximate the handle and a narrower end of the body is distal relative to the handle, and wherein an average diameter of at least some of the branches located at or towards the distal end is less than an average diameter of at least some of the branches located at or towards the proximal end.
20. A method of manufacturing an oral hygiene device with a cleaning element, the method comprising the following steps, in order: (a) mixing granules of a carrier plastic with granules of silica to form a first mixture; and (b) extruding the carrier mixture under heat and pressure to produce a cleaning element of an oral hygiene device.
21. A method of manufacturing an oral hygiene device with a cleaning element, the method comprising the following steps, in order: (a) mixing granules of a carrier plastic with granules of silica to form a first mixture; (b) extruding the carrier mixture under heat and pressure to produce pellets of a homogenous stock comprising the carrier plastic with the granules of silica distributed within; and (c) injection moulding an output of the previous step into a mould to form the abrasive cleaning element.
22. The method of claim 21 further comprising, between step (b) and step (c), the steps of: (b') mixing granules of a second plastic to the pellets of homogenous stock to form a second mixture; and (b') extruding the second mixture under heat and pressure to produce a further homogenous stock comprising: the carrier plastic; the second plastic; and the silica distributed within.