JP7548762B2 - toothbrush - Google Patents

Description

The present invention relates to a toothbrush.

Toothbrushes that remove plaque from the mouth have been known in which bundles of multiple folded bristles are inserted into multiple bristles holes formed in the bristles surface of the head and secured with a flat wire. In such toothbrushes, various measures have been taken with the arrangement and shape of the bristles and the shape of the tips of the bristles so that plaque can be effectively removed by efficiently brushing appropriately for the type of tooth (front teeth, back teeth, etc.) and the part of the tooth (tooth surface, interdental spaces, neck, etc.).

Patent Document 1 discloses an invention relating to a toothbrush in which the brush bristles that make up the bristles have tapered tips, and the tips of the bristles are cut off to form a mountain-shaped cut portion when the head is viewed from the side. Here, the bristles are divided into a cut off portion with one peak per bundle and a cut off portion with one peak per two bundles, and the height of the peaks of the cut off portion with one peak per two bundles and the cut off portion with one peak per one bundle are different. This allows the bristles to penetrate easily between the teeth, provides excellent contact with the gums and a cleaning feeling, and effectively removes plaque from every corner of the oral cavity.

JP 2004-129683 A

In order to effectively remove plaque from the mouth, it is important for the bristles to reach areas that are difficult to reach, such as between the teeth and the gum line. For this reason, many toothbrushes have been developed that use tapered bristles that are deeply tapered from the tip to the base. Even in the toothbrush described in Patent Document 1, the longer the tapered bristles are, the sharper the bristles are, forming a deeper tapered shape.

However, when a deep taper shape is formed, although the ability to reach between teeth and the like is improved, the rigidity of the brush bristles is reduced, resulting in weaker bristles. As a result, not only is the cleaning effect on the tooth surface reduced, but the cleaning effect on the interdental spaces and the neck of the teeth is also unsatisfactory.

In order to solve the above problems, the toothbrush of the present invention has a bristle bundle made up of a plurality of brush bristles fixed to each of a plurality of bristle implantation holes formed on the bristle implantation surface of a head portion, and has a mountain-shaped section at the tip of one or more of the bristle bundles, and a flat section at the tip of one or more of the bristle bundles that is approximately parallel to the bristle implantation surface, and the length of the bristle bundle protruding from the bristle implantation surface at the mountain-shaped section is longer than the length of the bristle bundle protruding from the bristle implantation surface at the flat section, and the tip of the bristles of the bristle bundle at the mountain-shaped section has a distance of 0.15 mm or more from the tip of the bristles. A rounded edge portion is formed in a range of 0.40 mm or less, in which the radial width gradually decreases toward the tip, and in the bristle bundle in the mountain cut portion that has the longest protruding length from the bristle implantation surface, the radial width at a portion 0.05 mm from the tip of the bristle in the rounded edge portion is 20% to 80% of the radial width of the filament that forms the bristle, and the radial width at a portion 0.1 mm from the tip of the bristle in the rounded edge portion is 30% to 100% of the radial width of the filament that forms the bristle.

In conventional brush bristles with a tapered tip, the tapered part is formed in a range of approximately 1 mm to 3 mm from the tip of the brush bristles. In some brushes with a particularly deep tapered shape, the tapered part is formed in a range of approximately 8 mm to 9 mm from the tip of the brush bristles. In this regard, according to the above configuration, the round edge part, whose radial width gradually decreases toward the tip, is formed in a range of 0.15 mm to 0.40 mm from the tip of the brush bristles. Therefore, compared to brush bristles with conventional tapered parts, the reduction in rigidity is suppressed, and the reduction in bristles stiffness is suppressed. This improves the cleaning effect on the tooth surface, tooth neck, etc. In addition, compared to brush bristles with a hemispherical tip rounded tip or a flat tip flat tip, the brush bristles have excellent reachability to areas that are difficult for brush bristles to reach, such as between the teeth and the gingival margin. Furthermore, some of the bristles fixed to the multiple bristle implantation holes form a mountain-shaped mountain-shaped part as a whole. Therefore, the bristles that make up the crests can easily conform to the side shape of the tooth row, improving the ability to reach areas that are difficult for brush bristles to reach, such as between the teeth and around the gum line. Plaque can be effectively removed from the entire oral cavity, improving cleaning performance.

The round edge portion can also be said to have a tapered shape in that the radial width gradually decreases toward the tip. However, compared to conventionally known brush bristles with tapered tips, the tapered shape is formed over a shorter area and only in a small portion of the tip of the brush bristles. In brush bristles where the portion where the radial width gradually decreases toward the tip is formed in a range of 0.15 mm to 0.40 mm from the tip, this portion is called the round edge portion.

In the above configuration, it is preferable that the brush bristles of the bristle bundle at the crest portion are spiral bristles.
Here, the spiral bristles refer to those formed by twisting the filaments that make up the brush bristles in the axial direction. The spiral bristles form fine irregularities on the sides of the brush bristles, which can effectively remove plaque that is difficult to remove from the tooth surface, as well as plaque that remains between the teeth and on the gum line.

In the above configuration, it is preferable that the tips of the bristles of the bristle bundle at the flat portion have a rounded tip shape.
According to the above-mentioned configuration, the bristle bundles in the flat portion can provide rigidity, thereby improving the cleaning performance of the entire oral cavity.

The toothbrush of the present invention can effectively remove plaque from the entire oral cavity, improving cleaning performance.

1A is a schematic diagram of a head portion of a toothbrush according to an embodiment of the present invention; FIG. 1B is a top view of the head portion without bristles implanted therein; FIG. 1A is a partially enlarged view of the brush bristles, and FIG. 1B is a partially enlarged view of the rounded edge portion of the brush bristles. (a) is an enlarged view of tapered brush bristles, and (b) is an enlarged view of rounded brush bristles. FIG. 11 is a diagram showing the results of an evaluation test of cleaning performance. FIG. 13 is a diagram showing the results of an evaluation test of usability.

Hereinafter, one embodiment of the toothbrush of the present invention will be described.
1(a) and (b), a plurality of bristle implantation holes 3 are formed in the bristle implantation surface 2a of the head portion 2 of the toothbrush 1. The number, shape, and arrangement of the bristle implantation holes 3 can be set as desired. In the toothbrush 1 of this embodiment, 22 bristle implantation holes 3 are arranged in seven rows along the longitudinal direction of the toothbrush 1. In the following description, the head portion 2 side in the longitudinal direction of the toothbrush 1 is referred to as the tip side, and the handle side of the toothbrush 1 is referred to as the base side.

As shown in FIG. 1(a), a bristle bundle 4 made up of multiple brush bristles 10 made of synthetic resin filaments is fixed in each bristle hole 3. The number of brush bristles 10 constituting one bristle bundle 4 is not particularly limited. For example, it can be about 10 to 20. Methods for fixing the bristle bundle 4 include folding multiple brush bristles 10 in half and inserting them into the bristle hole 3 together with a flat metal wire, or fusing them to the inside of the bristle hole 3 with heat.

As shown in FIG. 1(a), when the head portion 2 is viewed from the side, the hair bundles 4 fixed to the hair implantation holes 3 formed in the second and third rows from the tip of the head portion 2 form a mountain-shaped mountain-cut portion 5 where the tips of the hair bundles 4 form a mountain-shaped overall. The mountain-cut portion 5 is formed in a mountain shape with the apex being the position where the hair bundles 4 in the second and third rows face each other in the longitudinal direction of the head portion 2, by cutting the tips of the hair bundles 4 in the second and third rows into a mountain-shaped overall. The apex of the mountain-cut portion 5 extends along the short direction of the head portion 2. The hair bundles 4 fixed to the hair implantation holes 3 formed in the first row and the fourth to seventh rows from the tip of the head portion 2 other than the mountain-cut portion 5 form a flat portion 6 where the tips of the hair bundles 4 are approximately parallel to the hair implantation surface 2a. In FIG. 1(b), the bristle implantation holes 3 into which the bristle bundles 4 that make up the mountain cut portion 5 are implanted are indicated by black circles, and the bristle implantation holes 3 into which the bristle bundles 4 that make up the flat portion 6 are implanted are indicated by white circles.

As shown in FIG. 1(a), the protruding length H1 of the bristle bundle 4 from the bristle implantation surface 2a at the crest 5 is longer than the protruding length H2 of the bristle bundle 4 from the bristle implantation surface 2a at the flat portion 6. The protruding length H1 is preferably about 8.0 mm or more and 12.0 mm or less, and more preferably about 9.0 mm or more and 11.0 mm or less. Furthermore, the protruding length H2 is preferably about 1.0 mm to 2.0 mm shorter than the protruding length H1. The formation of the crest 5 and the flat portion 6 with this degree of difference in protruding length improves the reach of the brush bristles 10 to the interdental spaces, the gingival margins, etc.

The material of the filaments constituting the brush bristles 10 of the bristle bundle 4 in the crested portion 5 and flat portion 6 is not particularly limited, and any conventionally known synthetic resin material can be used. Examples of synthetic resin materials include polyamides such as nylon 610 and nylon 612, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, polyolefins such as polypropylene, olefin-based elastomers, and styrene-based elastomers. Among these, from the viewpoint of strengthening the stiffness of the brush bristles 10, polyamides such as nylon 610 and nylon 612 and polybutylene terephthalate are preferred.

The hardness of the filaments constituting the brush bristles 10 of the bristle bundle 4 in the crested portion 5 and the flat portion 6 can be set as appropriate. The hardness of the brush bristles 10 may be constant in each bristle implantation hole 3, or the hardness of the brush bristles 10 may be varied in some of the bristle implantation holes 3. For example, harder brush bristles 10 may be used for the brush bristles 10 constituting the bristle bundle 4 in the crested portion 5, and normal brush bristles 10 may be used for the brush bristles 10 constituting the bristle bundle 4 in the flat portion 6.

Filaments constituting the brush bristles 10 may be round bristles with a circular cross-sectional shape in the radial direction, or spiral bristles twisted in the axial direction to have a square cross-sectional shape in the radial direction. All of the bristles 4 of one toothbrush 1 may be composed of spiral bristles, or the bristles 4 of one toothbrush 1 may be a mixture of bristles 4 composed of round bristles and bristles 4 composed of spiral bristles. In the toothbrush 1 of this embodiment, the bristles 4 in the crest portion 5 are composed of spiral bristles, and the bristles 4 in the flat portion 6 are composed of round bristles.

Next, the shape of the tips of the brush bristles 10 constituting the bristle bundle 4 fixed in the bristle implantation hole 3 will be described together with its function.
As shown in Fig. 2(a), the brush bristles 10 constituting the bristle bundle 4 in the mountain cut portion 5 have a rounded edge portion 21 at their tips, the radial width of which gradually decreases toward the tip. The rounded edge portion 21 is formed by physically grinding the tip of the bristle bundle 4 fixed in the bristle implantation hole 3 with a grinder or the like. The axial length H3 of the rounded edge portion 21 is 0.15 mm or more and 0.40 mm or less. In other words, the rounded edge portion 21 is formed in a range of 0.15 mm or more and 0.40 mm or less from the tip of the brush bristles 10.

As shown in FIG. 2(b), the radial width L1 at the portion 0.05 mm from the tip of the brush bristles 10 in the round edge portion 21 is preferably in the range of 20% to 80% of the radial width L4 of the filament forming the brush bristles 10, and more preferably in the range of 31% to 60%. The radial width L2 at the portion 0.1 mm from the tip of the brush bristles 10 in the round edge portion 21 is preferably in the range of 35% to 100% of the radial width L4 of the filament forming the brush bristles 10, and more preferably in the range of 49% to 87%. Furthermore, the radial width L3 at the portion 0.15 mm from the tip of the brush bristles 10 in the round edge portion 21 is preferably in the range of 50% to 100% of the radial width L4 of the filament forming the brush bristles 10, and more preferably in the range of 64% to 100%. The radial width refers to the "length of a line segment passing through the center of the radial cross section of the brush bristles 10". In other words, for round bristles whose radial cross-section is circular, the radial width corresponds to the diameter, and for spiral bristles whose radial cross-section is square, the radial width corresponds to the diagonal.

As shown in Figures 3(a) and (b), brush bristles 10 having a tapered portion 22 formed at the tip and brush bristles 10 having a semi-spherical rounded tip portion 23 formed at the tip are conventionally known. In the following, brush bristles 10 having a rounded edge portion 21 may be referred to as rounded edge bristles 11, brush bristles 10 having a tapered portion 22 formed as tapered bristles 12, and brush bristles 10 having a rounded tip portion 23 formed as rounded tip bristles 13.

Conventionally known tapered bristles 12 have a tapered section 22 formed at the tip by chemically treating the filament used as the brush bristles 10. The axial length H4 of this tapered section 22 is generally about 1 mm to 3 mm, with some being about 8 mm to 9 mm. As a result, although it has excellent reachability to interdental spaces and gingival margins, the bristles are weak and have problems with cleaning. In addition, rounded-tip bristles 13 have excellent rigidity and are therefore excellent at cleaning smooth areas such as tooth surfaces, improving the durability of the toothbrush 1, but have problems with reaching interdental spaces and gingival margins.

In this regard, the rounded edge bristles 11, due to their shape, not only have good reachability to interdental spaces and gingival margins, but also provide a high cleaning effect. This is because the axial length H3 of the rounded edge portion 21 is 0.15 mm or more and 0.40 mm or less, which gives it superior rigidity compared to the tapered bristles 12. In addition, because the tips are sharper than the rounded bristles 13, they have good reachability to interdental spaces and gingival margins. In this way, by the brush bristles 10 that make up the bristle bundle 4 in the crest portion 5 being made up of rounded edge bristles 11, the disadvantages of the tapered bristles 12 and rounded bristles 13 can be covered and their advantages can be further improved.

On the other hand, the brush bristles 10 constituting the bristle bundle 4 in the flat portion 6 are composed of rounded bristles 13 with a semi-spherical rounded tip 23 formed at the tip. This makes the bristles strong and rigid, improving cleaning performance on the tooth surface.

Next, the effects of the toothbrush 1 of this embodiment will be described.
(1) In the toothbrush 1 of this embodiment, the tips of the bristles 10 of the bristle bundle 4 at the crest portion 5 are formed with rounded edges 21 whose radial width gradually decreases toward the tips.

Therefore, compared to brush bristles 10 with a rounded tip 23 or brush bristles 10 with a flat tip, the brush bristles 10 have excellent reach to areas that are difficult for brush bristles 10 to reach, such as between teeth and the gum line. Also, compared to brush bristles 10 with a conventional tapered section 22, the reduction in rigidity is suppressed, making the bristles stronger. This improves cleaning of the tooth surface, as well as between teeth and the gum line. Plaque can be effectively removed from the entire oral cavity, improving cleaning of the entire oral cavity.

(2) In the toothbrush 1 of this embodiment, the bristle bundles 4 fixed to the bristle implantation holes 3 in the second and third rows from the tip of the head portion 2 form a mountain-shaped crest portion 5, and the bristle bundles 4 fixed to the bristle implantation holes 3 in the other rows form a flat portion 6 with a protruding length H2 shorter than the crest portion 5.

Therefore, the crest 5 can easily conform to the side shape of the tooth row, and the brush bristles 10 having the rounded edge 21 can easily reach between the teeth, the gum line, etc. The cleaning ability of the toothbrush 1 is improved.
(3) In the toothbrush 1 of this embodiment, the bristle bundles 4 in the crest portion 5 use spiral bristles with rounded edges 21 formed at the tips.

As a result, improved bristles and reach improve the cleaning effect not only on the tooth surfaces and necks, but also between the teeth and on the gum lines. In addition, the fine irregularities formed on the periphery of the spiral bristles make it possible to effectively remove plaque that is difficult to remove.

(4) In the toothbrush 1 of this embodiment, the bristle bundles 4 in the flat portion 6 include bristles 10 with rounded tips.
Therefore, rigidity can be imparted by the bristle bundles 4 at the flat portion 6. This can improve the cleaning performance of the entire oral cavity.

The above embodiment can be modified as follows: The above embodiment and the following modified examples can be applied in combination with each other to the extent that there is no technical contradiction.
The tufting holes 3 do not have to be formed in seven rows in the longitudinal direction of the head portion 2. They may be six rows or less, or eight rows or more. The number, shape, arrangement, etc. of the tufting holes 3 are not particularly limited.

For example, the ridges 5 may be formed in the third or fourth row from the tip of the head portion 2.
The crest 5 does not have to be formed by two rows of bristle bundles 4 on the head portion 2. For example, it may be formed by one row of bristle bundles 4 out of seven rows arranged in parallel in the longitudinal direction of the head portion 2, or it may be formed by three or more rows of bristle bundles 4. The crest 5 may also be formed in multiple places.

- In the toothbrush 1 of the above embodiment, the brush bristles 10 in the crest portion 5 are spiral bristles and the brush bristles 10 in the flat portion 6 are round bristles, but this is not limited to the above. For example, all of the bristles 4 may be composed of spiral bristles, or all of the bristles 4 may be composed of round bristles. In addition, the bristles 4 in the crest portion 5 may be a mixture of bristles 4 composed of spiral bristles and bristles 4 composed of round bristles.

- In the above embodiment, round bristles with a circular cross-sectional shape in the radial direction and spiral bristles with a rectangular cross-sectional shape in the radial direction are used as the filaments that make up the brush bristles 10, but the cross-sectional shape of the filaments used is not limited to this. In addition to circles and squares, examples of shapes that can be used include polygons such as semicircles, half-moons, triangles, and pentagons. In addition, irregular shapes such as irregular shapes are also acceptable.

- In FIG. 2, the rounded edge portion 21 is shown as having a shape that is symmetrical with respect to the central axis of the filament, but the shape of the rounded edge portion 21 is not limited to this. For example, it may be asymmetrical with respect to the central axis of the filament, with the tip of the rounded edge portion 21 being in a position offset from the central axis of the filament. In other words, when the filament is viewed from above, the apex of the mountain does not have to be in the center. More specifically, as long as the rounded edge portion 21 is formed in a shape in which the radial width gradually decreases toward the tip within a range of 0.15 mm to 0.40 mm from the tip of the brush bristles 10, it may be symmetrical or asymmetrical with respect to the central axis.

- The brush bristles 10 in the flat portion 6 may be configured with tapered bristles 12 having a conventionally known tapered shape.

The toothbrush of the present invention will be described in more detail with reference to the following examples. Note that the present invention is not limited to the configurations described in the examples.
<Specifying the Shape of the Round Edge Portion 21>
First, a number of prototypes with different shapes and hardness of the brush bristles 10 were created, and the shape and dimensions of the round edge portion 21 were specified.

(Prototype 1)
A toothbrush 1 having the shape shown in Fig. 1(a) and (b) was prototyped, and the dimensions of the round edge portion 21 were measured. In the second and third rows of bristle implantation holes 3 from the tip of the bristle implantation surface 2a of the head portion 2, a bristle bundle 4 made of spiral bristles made of nylon 610 was folded in half and inserted, and a flat wire was fitted and fixed. In the other bristle implantation holes 3, a bristle bundle made of brush bristles 10 (round bristles) made of nylon 610 was folded in half and inserted, and a flat wire was fitted and fixed. As the spiral bristles, those having a width of 0.178 mm and normal hardness were used. As the round bristles, those having a diameter of 0.200 mm and normal hardness were used. The number of spiral bristles filled was 16, and the number of round bristles filled was 17. After the brush bristles 10 were implanted in all the bristle implantation holes 3, the tips of the brush bristles 10 were cut to form a mountain cut portion 5 and a flat portion 6 as shown in Fig. 1(a). The protruding length H1 of the brush bristles 10 from the implanted surface 2a at the crest portion 5 was set to about 10.0 mm, and the protruding length H2 of the brush bristles 10 from the implanted surface 2a at the flat portion 6 was set to about 8.5 mm.

Then, a grinder was applied to the tips of the brush bristles 10 to form a rounded edge portion 21 at the tips of the brush bristles 10 at the crest portion 5, and a rounded tip portion 23 at the tips of the brush bristles 10 at the flat portion 6. The grinder was adjusted so that it hit a portion about 1.5 to 2.5 mm deep from the tip of the crest portion 5. The toothbrush 1 created in this way was designated prototype 1.

(Prototype 2)
The spiral bristles used were 0.229 mm wide and relatively hard, with 10 spiral bristles packed in, and the round bristles used were 0.250 mm in diameter and relatively hard, with 11 round bristles packed in. This prototype was created in the same way as prototype 1.

(Prototype 3)
In all of the bristle implantation holes 3 in the head part 2, bristle bundles made of nylon 610 round bristles were folded in half and inserted, and fixed with a flat wire. The round bristles used were 0.200 mm in diameter and of normal hardness. The bristle implantation holes 3 in the second and third rows from the tip of the bristle implantation surface 2a of the head part 2 were filled with 17 round bristles, and the other bristle implantation holes 3 were filled with 17 round bristles. The rest of the prototype was created in the same way as prototype 1.

(Prototype 4)
The round bristles used were made of nylon 610, had a diameter of 0.250 mm, and were relatively hard. The second and third rows of bristles 3 from the tip of the bristles implantation surface 2a of the head part 2 were filled with 11 round bristles, and the remaining rows of bristles 3 were filled with 11 round bristles. The rest of the prototype was created in the same way as prototype 1.

(Measurement of the dimensions of the round edge portion 21)
The dimensions of the rounded edge portion 21 of the brush bristles 10 at the mountain cut portion 5 were measured for prototypes 1 to 4. A microscope (product name VHX-6000, manufactured by Keyence Corporation) was used to measure the dimensions, and measurements were made 40 to 60 times for each prototype. The dimensions were measured by measuring the radial width of the brush bristles 10 at positions 0.05 mm, 0.1 mm, and 0.15 mm from the tip of the rounded edge portion 21. The maximum, minimum, average, and standard deviation (SD) of the measured values for each prototype were calculated as a percentage (%) of the radial width L4 of the filament forming the brush bristles 10. The results are shown in Table 1.

As shown in Table 1, the rounded edge 21 was formed to the same depth in the crest 5 for each of the prototypes 1 to 4. Although not shown in Table 1, when the depth of the rounded edge 21 for the prototypes 1 and 2 was measured with a microscope, it was found to be formed in a range of 0.15 mm to 0.40 mm from the tip of the brush bristles 10.

The measured value of the radial width L1 at the portion 0.05 mm from the tip of the brush bristles 10 in the rounded edge portion 21 was in the range of 20% to 80% of the radial width L4 of the filament forming the brush bristles 10. The measured value of the radial width L2 at the portion 0.1 mm from the tip of the brush bristles 10 in the rounded edge portion 21 was in the range of 35% to 100% of the radial width L4 of the filament forming the brush bristles 10. The measured value of the radial width L3 at the portion 0.15 mm from the tip of the brush bristles 10 in the rounded edge portion 21 was in the range of 50% to 100% of the radial width L4 of the filament forming the brush bristles 10. Note that, due to measurement errors, there were some portions where values greater than 100% of the radial width L4 of the filament forming the brush bristles 10 were measured, but these were recorded as 100% or less.

In addition, when the radial width of the brush bristles 10 in the rounded edge portion 21 is viewed as an average value ± SD, the radial width L1 at the portion 0.05 mm from the tip of the brush bristles 10 in the rounded edge portion 21 was in the range of 31% to 60% of the radial width L4 of the filament forming the brush bristles 10. Similarly, the radial width L2 at the portion 0.1 mm from the tip of the brush bristles 10 in the rounded edge portion 21 was in the range of 49% to 87% of the radial width L4 of the filament forming the brush bristles 10, and the radial width L3 at the portion 0.15 mm from the tip of the brush bristles 10 in the rounded edge portion 21 was in the range of 64% to 100% of the radial width L4 of the filament forming the brush bristles 10.

<Evaluation of cleaning ability>
Next, the cleaning ability was evaluated using the toothbrush 1 of the embodiment having brush bristles 10 with rounded edge portions 21 formed at the tips, and the toothbrush 1 of the comparison example having only brush bristles 10 with rounded, tapered tips.

Example 1
The toothbrush 1 prepared as the above-mentioned prototype 1 was used as the toothbrush 1 of Example 1. Bristle bundles 4 made of spiral bristles made of nylon 610, 0.178 mm wide and of normal hardness, were fixed to the second and third rows of bristle implantation holes 3 from the tip of the bristle implantation surface 2a of the head portion 2.

Example 2
The toothbrush 1 prepared as the above-mentioned prototype 2 was used as the toothbrush 1 of Example 2. Bristle bundles 4 made of nylon 610, 0.229 mm wide, and made of relatively hard spiral bristles were fixed to the second and third rows of bristle holes 3 from the tip of the bristle implantation surface 2a of the head portion 2.

(Comparative Example 1)
A head portion 2 having bristle implantation holes 3 as shown in Fig. 1(b) was used, and brush bristles 10 similar to those in Example 1 were inserted into each bristle implantation hole 3 and fixed by fitting a flat wire. The width, hardness and number of spiral bristles, and the width, hardness and number of round bristles were the same as those in Example 1. After the brush bristles 10 were implanted into all of the bristle implantation holes 3, the tips of the brush bristles 10 were cut to form a flat portion 6 overall. The protruding length H2 of the brush bristles 10 from the implantation surface 2a at the flat portion 6 was set to about 8.5 mm.

Then, a grinder was applied to the tips of the brush bristles 10 to form a tapered portion 22 at the tips of the brush bristles 10 at the flat portion 6. The grinder was adjusted so that it hit a portion about 2.5 to 3.5 mm deep from the tip of the flat portion 6. The toothbrush 1 created in this way was designated as Comparative Example 1.

(Comparative Example 2)
The toothbrush 1 produced in this manner was used as Comparative Example 2, except that the position where the grinder was applied was adjusted to a depth of about 0.5 to 1.5 mm from the tip of the flat portion 6, and rounded tip portions 23 were formed at the tips of the brush bristles 10 of the flat portion 6.

(Comparative Example 3)
As shown in Figure 1 (b), a head portion 2 having bristle implantation holes 3 formed therein was used, and brush bristles 10 similar to those in Example 2 were inserted into each bristle implantation hole 3 and fixed by fitting a flat wire. The width, hardness and number of spiral bristles, and the width, hardness and number of round bristles were the same as those in Example 2. After the brush bristles 10 were implanted in all of the bristle implantation holes 3, the tips of the brush bristles 10 were cut to form a flat portion 6 overall. The protruding length H2 of the brush bristles 10 from the implantation surface 2a at the flat portion 6 was set to approximately 8.5 mm.

The bristles 10 of the flat portion 6 were blind-processed in the same manner as in Comparative Example 1 to form tapered portions 22 at the tips of the bristles 10. The toothbrush 1 produced in this manner was designated Comparative Example 3.

(Comparative Example 4)
The toothbrush 1 produced in this manner was used as Comparative Example 4, except that the position where the grinder was applied was adjusted to a depth of about 0.5 to 1.5 mm from the tip of the flat portion 6, and rounded tip portions 23 were formed at the tips of the brush bristles 10 of the flat portion 6.

(Cleaning Efficiency Evaluation Test)
The toothbrushes of each embodiment and each comparative example were subjected to an evaluation test of cleaning ability. The evaluation test of cleaning ability was performed by preparing a jaw model coated with artificial plaque, and having a robot hold the toothbrush 1 of each embodiment and each comparative example, and brushing the cheek side of the jaw model (upper jaw) #26 to #23 for 2 seconds per tooth with an average brushing pressure of 150g, a stroke of 20mm, and a speed equivalent to 150rpm. After brushing, the removal rate (%) of artificial plaque on the entire tooth surface, between teeth, and on the tooth neck was calculated. The results are shown in Table 2 and Figure 4.

4, Example 1, in which the rounded edge portion 21 is formed at the tip of the brush bristles 10 at the crest portion 5, tends to have better interdental cleaning ability and better overall oral cavity cleaning ability than Comparative Example 1, in which the entire brush bristles are formed with a flat portion 6 and the tips of the brush bristles 10 are tapered, and Comparative Example 2, in which the entire brush bristles are formed with a flat portion 6 and the tips of the brush bristles 10 are rounded. In particular, the interdental cleaning ability of Example 1 was significantly higher than that of Comparative Example 2, in which the tips were rounded.

A comparison of Example 2, Comparative Examples 3 and 4, which used harder brush bristles 10, also showed similar trends to Example 1, Comparative Examples 1 and 2. Looking at the overall trends in the cleaning performance evaluation test, Example 1, which used normal hardness brush bristles 10, generally rated higher in cleaning performance than Example 2, which used harder bristles. This is thought to be because normal hardness brush bristles 10 provide better flexibility, which improves insertion between teeth and results in better overall cleaning performance.

(Usability evaluation test)
A test to evaluate the usability was conducted for the toothbrush 1 of Example 1, which has a rounded edge 21 formed at the tip, and Comparative Example 2, which has a rounded tip. The test to evaluate the usability was conducted by sensory evaluation of five items, "cleanability of tooth surface,""cleanability between teeth,""feel of insertion of the crest,""hardness of the crest," and "cleaning feel," based on a score of 1 to 7. The closer the score is to "7," the better the evaluation. The results are shown in Table 3 and Figure 5.

5, Example 1, in which the rounded edge portion 21 is formed at the tip of the brush bristles 10 at the mountain cut portion 5, was equivalent in all evaluations to Comparative Example 2, in which the entire brush bristles were composed of a flat portion 6 and the tips of the brush bristles 10 were rounded. By forming the rounded edge portion 21, the tips of the brush bristles 10 are sharper than those of the rounded tip shape, but it is believed that there is almost no deterioration in the feeling of use due to this.

H1, H2: projection length L1, L2, L3, L4: width 1: toothbrush 2: head portion 2a: bristle implantation surface 3: bristle implantation hole 4: bristle bundle 5: mountain cut portion 6: flat portion 10: brush bristles 21: round edge portion

Claims (3)

A toothbrush having a head portion, a bristle bundle consisting of a plurality of brush bristles fixed to each of a plurality of bristle implantation holes formed on the bristle implantation surface, and one or more tips of the bristle bundles having a mountain-shaped mountain portion as a whole and a flat portion having a tip end that is approximately parallel to the bristle implantation surface,
a protruding length of the tuft from the implantation surface at the mountain cut portion is longer than a protruding length of the tuft from the implantation surface at the flat portion;
A tapered round edge portion is formed at the tip of the brush bristles of the bristle bundle in the mountain cut portion,
The round edge portion has an axial length from the tip of the brush hair of 0.15 mm or more and 0.40 mm or less,
The brush bristles of the bristles in the flat portion have a semi-spherical rounded tip portion formed at the tip portion,
In the bristles of the bristles having the longest protruding length from the bristle implantation surface in the bristle bundle at the peak cut portion, the radial width at a portion 0.05 mm from the tip of the bristles in the rounded edge portion is between 20% and 80% of the radial width of the filaments forming the bristles, and the radial width at a portion 0.1 mm from the tip of the bristles in the rounded edge portion is between 30% and 100% of the radial width of the filaments forming the bristles. A toothbrush having a head portion, a bristle bundle consisting of a plurality of brush bristles fixed to each of a plurality of bristle implantation holes formed on the bristle implantation surface, and one or more tips of the bristle bundles having a mountain-shaped mountain portion as a whole and a flat portion having a tip end that is approximately parallel to the bristle implantation surface,
a protruding length of the tuft from the implantation surface at the mountain cut portion is longer than a protruding length of the tuft from the implantation surface at the flat portion;
A tapered round edge portion is formed at the tip of the brush bristles of the bristle bundle in the mountain cut portion,
The round edge portion has an axial length from the tip of the brush hair of 0.15 mm or more and 0.40 mm or less,
A tapered portion is formed at the tip of the brush bristles of the bristles in the flat portion,
The tapered portion has an axial length from the tip of the brush bristles of 1 mm or more,
In the bristles of the bristles having the longest protruding length from the bristle implantation surface in the bristle bundle at the peak cut portion, the radial width at a portion 0.05 mm from the tip of the bristles in the rounded edge portion is between 20% and 80% of the radial width of the filaments forming the bristles, and the radial width at a portion 0.1 mm from the tip of the bristles in the rounded edge portion is between 30% and 100% of the radial width of the filaments forming the bristles. 3. The toothbrush according to claim 1 , wherein the bristles of the bristle bundle at the crest portion are spiral bristles.