FIELD OF THE INVENTION

This invention relates to toothbrushes, in particular to the bristle configuration of toothbrush heads. Especially this invention relates to improved toothbrush bristle configurations comprising different types of bristle filaments in a specified arrangement.

BACKGROUND TO THE INVENTION

Toothbrushes are well established devices for oral hygiene. They are used to clean the teeth, to remove residues between and on the teeth and to remove dental plaque on tooth surfaces. Dental plaque is one of the major causes of tooth decay and periodontal problems such as gingivitis and periodontal disease, for example periodontitis.

Toothbrushes generally comprise a toothbrush head and a handle. The toothbrush head generally is an ovoid, oval or rectangular plate with tufts of bristles extending from one surface. This bristled surface of the toothbrush head is referred to in the art as bristle surface. The bristles are the cleaning moiety of the toothbrush. Depending on the material of the bristles and the toothbrush head, numerous techniques to attach the bristles or tufts of bristles to the bristle surface are known. For example, polymeric plastic filaments can be cut and u-folded to double-ended bristles, bundled and bound in small metal anchors to form tufts. The anchors can be press-fitted into depressions, often referred to as tuft holes, provided for the tufts on the bristles surface of the toothbrush head. The toothbrush head may be injection moulded from thermoplastic elastomer with said tuft holes foreseen on the bristle surface. The resilience of the thermoplastic elastomer of the toothbrush head fixes the anchors and thus the tufts of bristles to the bristle surface.

The toothbrush head is connected or connectable to a handle, which often has an ergonomic grip portion. The grip portion is used to grab and hold the toothbrush with one hand and to guide the brushing movement of the toothbrush head in the mouth during brushing. In the art, the connecting portion between the handle and the toothbrush head is often referred to as neck or neck region. The neck can be equipped with a flexible region, for example as disclosed in W012120014 Al. Flexing implements in the flexible region bend when a user brushes with too high brushing force. This prevents excess pressure on the teeth and gums.

Manual toothbrushes need to be moved by hand action. Electric toothbrushes make automated bristle motions such as rotating oscillation or back-and-forth-oscillation. There also exist semi-electric toothbrushes that are designed like manual toothbrushes but are equipped with means for vibration of the toothbrush head.

Toothbrush bristles are filaments primarily made from polymeric plastic material. Many different types of filaments for toothbrush bristles are known. Unitary bristles are made of a single polymer material filament, typically polyamide (e.g. PA 10.10 or nylon such as Nylon 6.12) such as the bristle materials Medex or Tynex or polybutylene terephthalate (PBT). They are of generally uniform circular cross-section and normally end-rounded, i.e. having their ends remote from the bristle surface rounded to prevent damage to the soft mouth tissues such as the gums. Filaments are available in different cross-sectional diameters resulting in soft (for example 0.15mm diameter) to rigid (for example 0.38mm diameter) bristles. Rigid unitary bristles achieve good cleaning of exposed tooth surfaces. They are less flexible than soft bristles which can cause gingival irritation, damage, and bleeding. Furthermore, rigid unitary bristles are too thick to penetrate between in the interproximal spaces between the teeth to remove residues in the interproximal spaces and to remove plaque on the mesial or distal tooth surfaces. Soft unitary bristles are thinner and thus les rigid. This reduces risk of damage to the gingiva. Soft unitary bristles also achieve better penetration to the interproximal spaces than rigid unitary bristles. However, soft unitary bristles are less durable due to flexing, bending and wear. Brushing with a toothbrush with soft bristles also requires longer brushing time for sufficient cleaning and plaque removal because the soft bristles may bend under brushing pressure.

Tapered bristles are made from unitary filaments that are tapered on their free end, i.e. the end remote from the bristle surface which is in contact with the teeth when used for brushing. The tapered bristles may be made from filaments of polyamide (nylon such as Nylon 6.12), or polyester such as polybutylene terephthalate (PBT). Mechanically tapered bristles in which the ends of the filaments are mechanically ground to a point, and chemically tapered bristles in which the ends of the filaments are chemically eroded to a point, are used in the art. PBT bristles are preferably eroded chemically to a tapered end. Chemically tapered bristles normally taper to a finer point than mechanically tapered bristles. Tapered bristles have different bending and flexibility characteristics from non-tapered bristles. Tapered bristles have particular good penetration in the interproximal spaces. They achieve a good plaque removal on the mesial and distal tooth surfaces and the subgingival margin. As they have fine ends, they are gentle to the gingiva which is especially preferred for people suffering from periodontitis or the like. However, due to their softness and limited brushing force they require longer brushing times for plaque removal. They are also susceptible to wear e.g. because of bending, folding, and breaking.

There remains thus a need for a toothbrush that combines effective, quick cleaning of the teeth, especially the exposed surfaces of the teeth, whilst still achieving good penetration into the interproximal spaces and subgingival margin with good plaque removal in those areas, and having low risk of irritation of the gingiva. Toothbrushes striking this balance are especially suited to prevent periodontal problems such as gingivitis and periodontal disease, for example periodontitis. They are also especially suited in situations where such periodontal problems already exist, to prevent further aggravation and disease progression, and to support recovery of the gingiva. SUMMARY OF THE INVENTION

The present disclosure provides a toothbrush head connected to or connectable to a handle to define a head-handle longitudinal direction and a widthways direction perpendicular to the longitudinal direction, the head having a bristle surface with a distal end further from the handle and a proximal end closer to the handle, a left side and a right side. Tufts of bristles extend from the bristle surface, wherein the tufts of bristles comprise first tufts comprising first bristles with rounded tips and second tufts comprising second bristles which are tapered. According to the invention, some of the first tufts are arranged in a circular nest outermost closest to the distal end, and second tufts are arranged on the left side and the right side of the bristle surface, with first tufts being arranged between the second tufts.

In one embodiment, the second tufts consist solely of second bristles.

In one embodiment, the first tufts of the nest have a diagonal cut with the length of the bristles increasing towards the distal end of the bristle surface.

In one embodiment there are six to 16 second tufts, preferably eight to 12, most preferably 10 second tufts.

In one embodiment, there are 15 to 23 second tufts.

In one embodiment, the second bristles have a length, measured from where the second bristles protrude from the bristle surface, which is uniform for all second bristles.

In one embodiment, the length of the second bristles is longer than the lengths of any other bristles on the bristle surface.

In one embodiment, the length of the second bristles is greater than 12mm, and the length of the first bristles ranges from 9mm to 11.5mm.

In one embodiment, the first bristles are non-tapered, end-rounded soft bristles with a circular cross-section with a diameter of around 0.15mm

In one embodiment, the second bristles are chemically tapered PBT bristles with a circular cross-section with a diameter of around 0.15mm.

In one embodiment, there are only first tufts and second tufts on the bristle surface, and some of the first tufts are arranged in a row extending widthways closest to the proximal end and some of the first tufts are arranged centrally, inwardly from second tufts, on the bristle surface. Preferably this row extending widthways consists of four first tufts. Preferably, the first tufts which are arranged centrally, inwardly from second tufts, on the bristle surface comprise two longitudinal rows of at least three tufts. There is also provided a toothbrush comprising a toothbrush head as disclosed herein.

The bristle surface preferably is planar. The bristles, grouped in tufts, protrude from the bristle surface in a bristle direction. The bristle direction may be uniform for all bristles or may differ for different tufts. It is preferred that the bristle direction is uniform for all bristles. It may be perpendicular to the bristle surface, or it may be inclined relative to the head-handle longitudinal direction or the widthways direction. Preferably, the bristle direction of the first tufts is perpendicular to the bristle surface. Preferably, the bristle direction of the second tufts is perpendicular to the bristle surface. Most preferred is that the bristle direction of all first and second tufts is perpendicular to the bristle surface. In embodiments with a planar bristle surface, it is most preferred that all first and second tufts extend from the bristle surface in a bristle direction that is perpendicular to the head-handle longitudinal direction and to the widthways direction. In embodiments comprising other types of tufts additional to the first and second tufts, it is preferred that all tufts extend from the bristle surface in a bristle direction perpendicular to the bristle surface.

Typically, there are 20 to 38 tufts on the toothbrush head. According to a preferred embodiment of the invention there are 29 tufts. There may be additional types of tufts in addition to the first and second tufts. However, it is preferred that there are only first and second tufts, with more first tufts than second tufts.

The tufts may be fixed on the toothbrush head with a method known in the art. Preferably, the tufts are implanted in the toothbrush head with the metal anchor technique. Small metal anchors are used to bind the individual bristles into tufts. These metal anchors are then inserted into tuft holes on the bristle surface. The resilience of the plastic material of the toothbrush head holds the metal anchors in place. It is emphasised, however, that the specific and beneficial bristle arrangement as disclosed herein is not limited to any tufting and/ or implantation method. The bristle arrangement as disclosed herein may be realised with any tufting and/ or implantation method. For example, in another well-known process, ends of the tufts may be supported extending into a mould cavity in which the toothbrush head is to be moulded, and molten plastics material may be injected in a fluid state around these ends so that the ends are firmly embedded in the toothbrush head when the injected plastic material hardens.

There may be 15 to 23 first tufts. Preferably, there may be 16 to 22 first tufts, most preferably 7 tufts forming a circular nest at the proximal end of the bristle surface, and 10 to 12 additional first tufts. In embodiments with a total number of 29 tufts, preferably there are 7 first tufts forming a circular nest, and 12 additional first tufts, i.e. 19 first tufts in total. Some first tufts may be located directly on or close to an axis along the head-handle longitudinal direction or may be located left and right of said axis. Some first tufts may be arranged in a row extending widthways closest to the proximal end of the bristle surface. Preferably, the first tufts are arranged axis symmetric, to the axis along the head-handle longitudinal direction, on the bristle surface. The first tufts have a generally circular cross section, typically having a diameter of about 1.0mm to about 2mm. The first tufts comprise first bristles. The first tufts may additionally comprise other bristles. It is preferred, however, that the first tufts are entirely made of first bristles. The first bristles are uniform, end-rounded bristles. The first bristles may be made from polyamide filaments e.g. nylon such as Nylon 6.12, or from polybutylene terephthalate (PBT) or polyethylene terephthalate (PET). Preferably, the first bristles are made from polyamide filaments, namely PA 10.10. Preferably the polyamide material is made from biological materials, for example from ricin plants. The first bristles are of a generally uniform, circular cross-section and are non-tapered and end-rounded, i.e. their ends remote from the bristle surface are rounded, to prevent damage to the soft mouth tissues such as the gums. The first bristles typically have a diameter of about 0.12mm to about 0.18mm. Most preferred is a diameter of about 0.15mm. This strength provides good elasticity of the bristles and makes them suitable for sensitive gums. At the same time, they still ensure satisfactory cleaning and plaque removal.

Preferably the first tufts of the circular nest at the distal end of the toothbrush end have a diagonal cut with the length of the bristles increasing towards the distal end of the bristle surface. This diagonal cut improved the cleaning performance in regions which are difficult to access, such as molars or wisdom teeth.

According to a preferred embodiment of the invention there are six to 16 second tufts, preferably eight to 12, most preferably 10 second tufts (16). For example, five or six second tufts can be arranged in a longitudinal row on the outer left and on the outer right side of the bristle surface, with first tufts being arranged in between these two rows of second tufts. Preferably, a row of first tufts extending widthways is arranged at the proximal end of the toothbrush head.

According to a preferred embodiment, the second bristles have a length which is greater than the length of any bristles on the bristle surface, to ensure they can access the interdental spaces.

Preferably, the second bristles have a diameter of 0.15mm at their stem. Higher diameters have been tested but were found to produce an unpleasant sensation in the mouth of the user without increasing the cleaning results. Users namely reported a poking or itching sensation which is believed to be due to the increased stiffness of tapered bristles with a higher diameter.

The toothbrush head of the disclosure may be a head of a manual toothbrush, i.e. to be moved in contact with the user's teeth solely by hand action, or the head of a power toothbrush in which the head is moved by an electric, e.g. battery powered, motor located in the handle. In the case of a power toothbrush the toothbrush head of the invention may be permanently connected or replaceable connectable to the toothbrush handle containing the drive motor by means well known in the toothbrush art, e.g. adapted to move the toothbrush head in a Bass-type motion under the action of the drive motor.

The toothbrush head may optionally further be equipped with a tongue cleaner. The tongue cleaner may be realised on a surface of the toothbrush head opposite of the bristle surface and may be made from thermoplastic elastomer by injection moulding. As a tongue cleaner is efficient in removing bacteria from the tongue, it is especially suitable in combination with the bristle arrangement of the present invention to provide a toothbrush that is especially suitable to prevent and relief gingival problems and periodontal disease.

The toothbrush head may further be optionally equipped with an impact protection implement. The impact protection implement may cover portions of the outer surface of the toothbrush head and cushions any impacts of the toothbrush head to the teeth and gingiva that may happen upon brisk brushing. Besides that, it gives the toothbrush head generally a soft and pleasant mouthfeel. It may be made from thermoplastic elastomer by injection moulding. Preferably, the impact protection implement covers lateral edges of the toothbrush head, and, optionally, in embodiments without tongue cleaner, also covers the surface opposite of the bristle surface. Thus the risk of hurting the gingiva is further diminished , which makes the impact protection implement especially suitable for the combination with the bristle arrangement as disclosed herein.

This disclosure further provides a toothbrush comprising a toothbrush head as disclosed herein. The toothbrush may optionally comprise handle implements to reduce excess brushing force. Examples of such implements are ball joints or a flexible links in the neck region. Those implements cushion excess pressure that a user may apply on the teeth by bending, which reduces the risk of gingiva damage by excess brushing force even further.

The invention will now be described by way of example only with reference to the accompanying figures.

DESCRIPTION OF DRAWINGS/FIGURES

FIG. 1 shows a perspective view of a toothbrush according to the invention.

FIG. 2 shows a perspective view of a toothbrush head according to the invention.

FIG. 3 shows a side view of the toothbrush head of FIG. 2.

FIG. 4 top plane view of the toothbrush head of FIG. 2 and 3.

FIG. 5A shows an automated plaque planimetry index on the buccal side.

FIG. 5B shows an automated plaque planimetry index on the lingual side.

FIG. 5C shows an automated plaque planimetry index on the mesial side.

FIG. 5A shows an automated plaque planimetry index on the distal side. DETAILED DESCRIPTION OF THE INVENTION

DEFINITIONS

The term "tapered bristles" or "tapered filaments" are terms of the toothbrush bristle art, a synonym being "pointed bristles" or "needle shaped bristles".

The term "soft bristles" or "soft filaments" is a term known to the person skilled in the art of developing, designing, and manufacturing toothbrushes

Length of bristles, unless indicated otherwise, is measured from where a bristle extends from the bristle surface.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a toothbrush comprising a toothbrush head 10 shown in more detail in FIG. 2. In the embodiment shown in FIG. 1, the toothbrush head 10 is made from two materials, namely polypropylene and a thermoplastic elastomer. In FIG. 1, it is also shown that the toothbrush head 10 is moulded in one piece with a toothbrush handle 20. Between the head 10 and the handle 20 there is formed a neck with a ball joint 15. The ball joint 15 reduces risk of damage to teeth or gums by excess brushing pressure. Further away from the head 10, with a flexible zone 22 is formed in the handle 20, in an area close to the neck and the ball joint 25. The flexible zone 22, also called a S-bend, bends when the user applies pressure, and therefore equally 15 reduces risk of damage to teeth or gums by excess brushing pressure. .

FIG. 2 shows the toothbrush head from FIG. 1 in more detail. The toothbrush head 10 has a flat bristle surface 12 (shown in FIG. 3 and FIG. 4) with a trapezoid outline with rounded edges, and is approximately 26mm long in a head-handle longitudinal direction (L-L). In the widthways direction (W-W) it is wider at its proximal end than at its distal end, with the maximum width being around 13mm. The head 10 comprises 29 bristle tufts 14, 16 in total, which project from a bristle surface 12. First tufts 14 consist of soft standard bristles 141 with a rounded end, whereas second tufts 16, shown with a tapered tip in FIG. 1 - 3, consist of tapered bristles 161.

A total of seven tufts 14 consisting of soft bristles 141 are arranged in a circle, also referred to as nest 15, at the distal end 12A of the bristle surface 12. The side view in FIG. 3 shows that the bristles 141 of this nest 15 have a diagonal cut, with the bristles being longer at the distal end 12A of the nest 15, and shorter at the proximal end of the nest 15. The length I2 of the longest of the standard soft bristles 141 in the nest 15 is about 11mm, and the length h of the shortest bristles 141 in the nest 15 is about 10mm.

Furthermore, four first tufts 14 consisting equally of standard soft bristles 141 are arranged in a row in widthways direction at the proximal end 12B of the bristle surface 12. These and all other standard soft bristles 141 outside of the nest 15 also have the shortest length h of 10mm.

At the left side 12D and the right side 12C of the bristle surface 12, five second tufts 16 of tapered bristles 161 are arranged in a row extending in a longitudinal direction L of the head. Between these two outer rows of second bristle tufts 16 consisting of tapered bristles 161, eight more first tufts 14 of rounded soft bristles are arranged, with six of these first tufts 14 forming two rows of three tufts 14 in a proximal area between the outer rows of second tufts 16, and two first tufts 14 being located in front of these two rows of three tufts towards the distal end of the head 10. These bristles 141 in these eight first tufts 14 also have the shortest length h of 10mm.

The soft standard bristles 141 of the first tufts 14 are filaments based on a polyamide material of biologic origin, namely a polymer mixture based on PA 10.10 Poly(decamethylene-sebacamide); possibly with functional additives and eventually with a colour agent. They are commercially available as Medex® Greenline Filaments, manufactured by Pedex GmbH / Perlon, and have a diameter of 0.15mm.

The tapered bristles 161 of the second tufts 16 are longer, as it is already visible in Fig. 1 and 2, and as shown in the side view of FIG. 3. The length 13 of these tapered bristles 161 is about 12.5mm, so that they extend beyond all of the standard soft bristles 141. The tapered bristles 161 are PBT tapered filaments, consisting mainly of poly(l,4-butylene terephthalate) and commercially available from BBC Co., Ltd., Korea. They also have a diameter of 0.15mm.

FIG. 4 shows a top view of the toothbrush head 10 and the bristle surface 12, which has an even and flat surface. On the bristle surface 12 there are 29 depressions, also referred to as tuft holes, into which the tufts of bristles are implanted. The tufts are implanted with a metal anchor technique, known in the art of toothbrushes. The tuft holes have a diameter of about 1.7mm.

For the first tufts 14, each tuft contains 72 +/-4 bristles 141 or filaments. For the second tufts 16, each tuft contains 80 +/-10 bristles 161 or filaments.

Outside of the nest 15 with its diagonal side cut, the length of all bristles within one same tuft 14, 16 will always be identical.

EXAMPLE

A manual toothbrush of the present disclosure comprising a toothbrush head as described above and as shown in FIG. 1 to 4 was assessed in terms of plaque removal efficacy. The test was a clinically validated brushing robot test comprising on a model of human teeth. The efficacy of plaque removal was assessed using an automated planimetrical plaque assessment analysing 30 fields per tooth, as illustrated in FIG 5A to 5D.

FIG. 5A shows the APP-Index buccally, i.e. towards the cheek, and FIG. 5B shows the APP index lingually, i.e. towards the tongue. FIG. 5C shows the APP Index mesially, i.e. proximal inbetween teeth on the anterior site, and FIG. 5D shows the APP Index distally, i.e. proximal in-between teeth on the posterior site.

A human tooth model was stained with artificial plaque, subjected to a defined robot brushing with horizontal, vertical, and rotating movements and a brushing force of 3.5N in anatomic position, and the reduction of stain from the 30 predefined areas of the surface of each tooth was assessed with an automated optical method. Special emphasis was on the "high risk" areas of the teeth: root surfaces or root fields, areas just above the root surfaces and close to the gumline, especially in the interproximal regions, where dental plaque is hard to remove, and which are most relevant for the prevention and alleviation of periodontal disease. The toothbrush according to the invention was compared to two reference toothbrushes. Reference toothbrush No. 1 was a commercially available toothbrush (Curaprox CS 1560) with a flat-trim cut and standard soft filaments with rounded ends, similar to the standard filaments 141 used in the first tufts 14 of the toothbrush of the present invention. Reference toothbrush No. 2 was a commercially available toothbrush (Meridol Sanft) with only chemically tapered filaments similar to the tapered filaments 161 used in the second tufts 16 of the toothbrush according to the invention. Brushing was performed at a brushing force of 3.5 N which corresponds to a medium brushing force. Three rounds of tests were run: horizontal, rotating, and vertical brushing movement, each with seven replicates.

The results are shown in Table 1 below:

% Plaque reduction Toothbrush Reference 1 (flat Reference 2

(mean±SD) according to trim) (tapered the invention bristles) The percentage of plaque reduction indicated in Table 1 corresponds to the mean of buccal and lingual surfaces together for EGHI and ABCDF, and the mean of mesial and distal surface together for XY. The percentage of plaque reduction was averaged across 7 runs per movement.

The statistical analysis was carried out by applying the Kolmogorov-Smirnov-test (KS-test, one sample test) to test the 11 variables of tooth surfaces - , buccal', , lingual', , mesial', , distal', , buccal risk fields ABCDF, , lingual risk fields ABCDF, ,W buccally', ,W lingually', ,W1+W2 mesially', ,W1+W2 distally' and , total' - for a normal distribution of cleaning efficacy/plaque removal values, while comparing two toothbrushes each time..

Significance level a = 0.10 (10%) was used to test this important assumption of arithmetic mean calculation and parametric t-test. As a result, the null hypothesis of normality was clearly rejected resp. not accepted for all of the 11 cleaning parameters / tooth surfaces.

The consequence is, that all parameters above-mentioned are analysed by a non-parametric Wiicoxon-Mann-Whitney-U-testijNWN- es. or U-test), to assess whether the rank sums and medians of the two tested toothbrushes (toothbrush according to the invention versus reference 1 and toothbrush according to the invention versus reference 2) are statistically different.

For both two-tailed tests of differences in cleaning efficacy between the two brushes, i.e. toothbrush according to the invention versus reference 1 and toothbrush according to the invention versus reference 2, the significance level is set at the basic p-value of 0.05 (5%) significant) (*). Significant differences Significance values at higher levels are called out specifically in Table 1: p-value of 0.01 (1%) (, very significant) **) and p-value of 0.001 (l%o) (, highly significant) (***).

The experiment showed that the toothbrush of the invention achieves significantly higher total percentage of plaque removal than the two reference toothbrushes for the gumline risk fields (ABCDF) and interdental risk fields (XY) in all three brushing movements. For vertical brushing of smooth surfaces (EGHI), the toothbrush according to the invention also achieved better results, with a high cleaning efficacy (comparable to the reference toothbrushes) still being given on smooth surfaces with horizontal and rotating brushing.

Toothbrushes with the bristle configuration of the present invention thus are optimal for plaque control at all risk areas, contributing to the prevention of dental caries and gingivitis.

List of reference numerals

10 head

12 bristle surface

12A distal end of bristle surface

12B proximal end of bristle surface

12C left side of bristle surface

12D right side of bristle surface

14 first tufts of first bristles

141 first bristle

15 nest

16 second tufts of second bristles

161 second bristle

20 handle

22 flexible zone (s-bend)

25 ball joint

W - width direction

L - length direction

11 minimal length of first tufts h maximal length of first tufts

13 length of second tufts