JP5779383B2 - toothbrush - Google Patents

Description

  The present invention relates to an improvement in a toothbrush.

In order to further prevent periodontal disease and dental caries, toothbrushes that have a higher cleaning power for the entire oral cavity are required.
The site | part in the oral cavity cleaned by the toothbrush is divided roughly into a tooth neck part, an interdental part, a tooth surface, and a back tooth. The flocking pattern of the toothbrush is appropriately set according to the part of the part that is desired to improve the cleaning property.
For example, in Patent Document 1, as a toothbrush that improves the cleanability of the interdental portion, the hair transplantation region of the head portion is divided into a central band-like region near the center line of the hair transplantation region from the base end of the head portion toward the tip, and the center. It has been proposed that the hair material is divided into outer regions sandwiching the belt-like region, and the average hair length of the hair material in the central belt-like region is longer than the average hair length of the hair material in the outer region.
Patent Document 2 proposes a toothbrush in which one non-planted portion is provided in the center of a flocked region for the purpose of adapting to the situation in the oral cavity of each individual.
Patent Document 3 proposes a toothbrush in which hair bundles are implanted in a V shape with the proximal end side of the flocked region opened for the purpose of polishing a region having no self-cleaning action in the oral cavity.

Japanese Patent No. 4076404 JP 2003-289944 A Utility Model Registration No. 3142558

However, the toothbrush described in Patent Document 1 cannot be said to be sufficient for cleaning of the tooth neck and the tooth surface. The toothbrush described in Patent Document 2 has insufficient penetrability of the hair tip into the tooth neck, and is not only insufficient in the cleaning performance of the tooth neck and the feeling of use at the time of cleaning the tooth neck. It is industrially inefficient to manufacture according to the individual oral condition. The toothbrush described in Patent Document 3 has few hair bundles implanted, and the spacing between the hair bundles is too wide, so that the feeling of use at the time of tooth surface cleaning is insufficient, and the stability during brushing is low, It was hard to polish.
Accordingly, the present invention provides a toothbrush that has high cleaning performance for both the neck and the tooth surface, is excellent in use feeling when cleaning the tooth neck and the tooth surface, and has high stability during brushing. Objective.

The present invention has the following aspects.
[1] In a toothbrush comprising a head portion in which a plurality of flocked holes are formed, a hair portion in which a plurality of bristles are bundled in the flocked hole, and a handle portion extended to the head portion. Side edge hair bundles adjacent to each other across the center line of the flocked region from the proximal end of the head portion to the distal end in a region of 35 to 75% of the length of the flocked region from the proximal end of the portion toward the distal end, Between a pair of side edge hair bundle groups formed by being implanted at a distance of 25 to 50% of the length in the direction perpendicular to the center line in the hair transplant region, and between the pair of side edge hair bundle groups A central hair bundle group formed by planting the central hair bundle, wherein the hair length of the central hair bundle is 90% or less of the hair length of the side edge hair bundle, Toothbrush.
[2] The toothbrush according to [1], wherein a flocked hole into which the side edge bristles and the central bristles are flocked has a hole cross-sectional area of 1.6 mm ² or less.
[3] The toothbrush according to [1] or [2], wherein at least a part of the bristles of the side edge bristle bundle is a bristles whose diameter gradually decreases toward the bristles.
[4] At least a part of the hair of the side edge hair bundle has a multi-core structure including a core part and at least one sheath part provided on the outer side of the core part, and faces the hair tip. The toothbrush according to [1] or [2], wherein the toothbrush is a polyester bristle whose diameter gradually decreases.

  The toothbrush of the present invention has high cleanability of the tooth neck and tooth surface, is excellent in the feeling of use at the time of cleaning the tooth neck and the tooth surface, and has high stability during brushing.

It is a side view which shows one Embodiment of the toothbrush of this invention. It is a top view which shows the flocked area | region in the toothbrush shown in FIG. It is sectional drawing at the time of cut | disconnecting the toothbrush shown in FIG. 1 in the direction orthogonal to the axial direction, Comprising: It is a figure which shows the side edge hair | bristle bundle and the center hair | bristle bundle planted by the head part. It is a schematic diagram explaining the effect which the toothbrush shown in FIG. 1 show | plays.

An embodiment of the toothbrush of the present invention will be described.
In FIG. 1, the side view of the toothbrush of this embodiment is shown. The toothbrush 1 of the present embodiment includes a head portion 10 in which the hair bundle 11 is implanted, and a long handle portion 20 extending from the head portion 10.

In the toothbrush 1, the head portion 10 and the handle portion 20 are integrally formed as a whole as a whole. For example, the head portion 10 and the handle portion 20 are obtained by injection molding using a resin as a material.
The resin can be determined in consideration of the rigidity and mechanical characteristics required for the toothbrush 1. For example, it is necessary for the toothbrush 1 to use a high-hardness resin having a flexural modulus (JIS K7203) in the range of 500 to 3000 MPa. Mechanical properties are obtained. Examples of such high-hardness resins include polypropylene (PP), polyethylene terephthalate (PET), polycyclohexylenedimethylene terephthalate (PCT), polystyrene (PS), acrylonitrile / butadiene / styrene resin (ABS), and cellulose propio. Nate (CP), polyarylate, polycarbonate, acrylonitrile / styrene copolymer resin (AS), and the like. These can use 1 type or multiple types.
Moreover, in the handle part 20, in order to improve the gripping property, for example, a flexible resin such as an elastomer may be partially or entirely covered.

As shown in FIG. 2, for example, a large number of circular flock holes 13 in a lattice arrangement are formed in the head portion 10, and a follicle bundle of a plurality of hairs is flocked into the flock holes 13. .
In the present invention, the region 12 in which the hair bundle in the head portion 10 is implanted is referred to as a “planted region 12”. Specifically, the flocked region 12 is a region surrounded by a virtual line T obtained when the outermost portions of the hole edges of the outermost flocked holes 13 are connected. This imaginary line T constitutes a tangent line between adjacent flock holes 13 and 13.

Further, in the head unit 10, the side edge hair bundles 11a and 11a (see FIG. 3) adjacent to each other across the center line M of the hair planting region 12 from the proximal end to the distal end of the head unit 10 are implanted so as to be spaced apart. The central hair bundle group formed by planting the central hair bundle 11b (see FIG. 3) between the pair of side edge hair bundle groups formed and the pair of side edge hair bundle groups, and the side edge hair bundle group And a front end hair bundle group which is arranged on the front end side of the central hair bundle group and is formed by planting the front end hair bundle 11c (see FIG. 3). Since the side edge hair bundle group is easily bent in the lateral direction of the toothbrush 1, the side edge hair bundle group is mainly involved in cleaning of the tooth neck, and the central hair bundle group and the tip hair bundle group are mainly in contact with the tooth surface. Involved in tooth surface cleaning.
In the present specification, a region located between the side edge regions 12a and 12a having the side edge hair bundle group and having the center hair bundle group is referred to as a “center region 12b”.

Direction length L ₁ extending from the proximal end to the distal end of the head portion 10 of the central region 12b is 35 to 75% of the length L ₂ in the direction of bristle region 12 toward the tip end from the base end of the head portion 10. Specifically, L ₁ is a flocking hole 13 in which the proximal end side of the head portion 10 in the flocked region 12 and the distal end hair bundle 11c on the proximal end side are planted in the direction from the proximal end to the distal end of the head portion 10. It is the distance from the base end side. More specifically, the L ₂ is a flocking hole 13 in which the proximal end side of the head portion 10 in the flocked region 12 and the distal end hair bundle 11c are planted in the direction from the proximal end to the distal end of the head portion 10. It is the distance from the most advanced side.
Further, Gawaenketaba 11a, the distance _{L 3} of 11a each other, the length 25-50% of the distance _{L 4} in the direction of the bristle region 12 perpendicular to the center line M. Wherein L ₃ is, in particular, the side edge tufts 11a adjacent to each other across the center line M is the distance of the innermost ends of bristles holes 13 that are flocked. The L ₄ is more specifically, in the direction perpendicular to the center line M, the outermost surface of the flocked hole 13 located on one side end side of the flocked region 12 and the flocked hole located on the other side end side. 13 is the distance from the outermost side.
If the L ₁ is less than 35% of the L ₂ , the ratio of the side edge hair bundle 11a decreases, and the cleaning performance of the tooth neck becomes insufficient. The balance of feeling of use is impaired. Further, since the ratio of the tip hair bundle 11c is reduced, the brushing stability tends to be lowered.
Wherein L ₃ is less than 25% of the L _4, it is insufficient as a flocking space of the central tuft 11b, even when planting a central tuft 11b, not trivial is flocked quantity, central tuft brushing pressure The group can not stand. Meanwhile, the _{L 3} is more than 50% of the _{L 4,} is impaired penetration of the cervical.

Moreover, in order to ensure sufficient cleaning of the tooth neck, the L ₁ is preferably 30% or more of the L ₂ . The L ₃ is preferably 30% or less of the L ₄ .

  In the present embodiment, the central region 12b is formed in a rectangular shape having a direction parallel to the center line M as a longitudinal direction. Thereby, about the side edge hair | bristle bundle 11a, the number of the direction parallel to the centerline M can be ensured enough, and the number of the hair | bristle bundle which a hair tip penetrates into a tooth neck part can fully be ensured.

  The size of the head unit 10 can be determined in consideration of the operability in the oral cavity, for example, the width is 10 to 15 mm, and the thickness is 4 to 8 mm.

The hair constituting the hair bundle 11 includes hairs (taper hairs) whose diameter gradually decreases toward the hair tips, and hairs having the same outer diameter (straight hairs) except for the rounded portion of the hair tips. Is mentioned.
Examples of the tapered bristles include those in which both ends are tapered, those in which only one end is tapered, and those in which a large number of sharp portions are formed in one hair.

It is not necessary that all the hairs implanted in the head portion 10 are of the same type, and the side edge hair bundle 11a, the center hair bundle 11b, and the tip hair bundle 11c may be different. The main role of the side edge hair bundle 11a is to remove plaque from the neck of the tooth, and the main role of the central hair bundle 11b and the tip hair bundle 11c is to clean the tooth surface. It is preferable to use it. Specifically, it is preferable that at least a part of the hair of the side edge bristle bundle 11a is a taper hair, and it is more preferable that the whole is a taper hair from the viewpoint of improving the cleaning performance of the tooth neck. Further, from the viewpoint of improving the tooth surface cleaning properties, it is preferable that at least a part of the hairs of the central hair bundle 11b and the tip hair bundle 11c is straight hair, and it is preferred that all are straight hair.
In addition, in the side edge hair | bristle bundle 11a, the center hair | bristle bundle 11b, and the front-end | tip hair | bristle bundle 11c, you may mix a taper hair and a straight hair.

The material of the hair is, for example, polyamide such as 6-12 nylon or 6-10 nylon, PET, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate ( Synthetic resin materials such as polyester such as PBN), polyolefin such as PP, elastomer such as olefin elastomer and styrene elastomer can be used.
A plurality of these resin materials may be used in combination, and among them, a mixture of a plurality of polyesters is preferable in that it can be easily strengthened and the plaque can be scraped more easily.
Moreover, the hair for polyester which has a multi-core structure provided with a core part and the sheath part of at least 1 layer or more provided in the outer side of this core part is also preferable. When a multi-core structure is used, different polyesters can be used for the core portion and the sheath portion, so that the mechanical properties can be easily adjusted. For this reason, it is possible to easily obtain hair having a strong stiffness and a higher plaque scraping property.

The cross-sectional shape of the bristle is preferably a circle, but is not necessarily limited to a circle, and can be any shape depending on the intended use of the toothbrush 1. For example, the shape may be an ellipse, a polygon (for example, a triangle, a quadrangle, a pentagon, a hexagon, or the like), an irregular shape (for example, a star shape, a three-leaf clover shape, a four-leaf clover shape, or the like).
When the cross section is circular, the firmness becomes stronger and the effect of scraping the dental plaque becomes higher. Therefore, the thickness (maximum diameter) of the hair is preferably 6 mil or more. However, when the hair is strengthened by using hair having a multi-core structure or hair made of a polyester mixture as hair, a high scraping effect can be obtained even if the hair is less than 6 mils.
Moreover, in consideration of a feeling of use, a feeling of cleaning, a cleaning effect, durability, and the like, a plurality of hairs having different thicknesses may be used in any combination.

The hair length of the hair is preferably 8 mm to 13 mm for adults and 6 mm to 9 mm for children from the flocked surface of the head portion 10.
Furthermore, in the toothbrush 1, as shown in FIG. 3, the bristle length of the center bristle bundle 11b is 90% or less of the bristle length of the side edge bristle bundle 11a, preferably 70-30%. Since the hair length of the center hair bundle 11b is 90% or less of the hair length of the side edge hair bundle 11a, a space is formed between the side edge hair bundles 11a and 11a on the center hair bundle 11b. In the present invention, the hair length of the hair bundle refers to the height on the surface (planted surface) on which the hair bundle of the head portion 10 is planted, that is, from the planted surface to the tip of the hair bundle (the tip of the longest hair). It is the distance to.
When the hair length of the central hair bundle 11b is short, equivalent or long in the range exceeding 90% of the hair length of the side edge hair bundle 11a, the cleaning performance of the tooth neck and the feeling of use when using the tooth neck are impaired. There is a tendency.
The side hair bundle 11a, the central hair bundle 11b, and the tip hair bundle 11c may or may not have the same length of hair.

As a method for implanting the hair bundle 11, a known method such as a method of driving a flat wire or a method of heat welding can be applied.
In the method of driving a flat wire, a plurality of bristles are bundled and folded in half, and a hair clip 11 is implanted in each flocked hole 13 by inserting a retaining tool called a flat wire between them and driving it into the flocked hole.
The flat line passes through the center of the flocked hole 13 and is placed in the flocked hole 13 so as to straddle the flocked hole 13. Examples of the material of the flat wire include metals such as brass and stainless steel, and other examples include hard plastic and biodegradable plastic.
The length, width, and thickness of the flat line may be arbitrarily adjusted according to the hair bundle 11 and the flock hole 13, but the length of the flat line is usually larger than the diameter of the flock hole 13, and the width of the flat line is It is made smaller than the depth of the flock hole 13. Further, by adjusting the thickness of the flat wire, the hair bundle 11 can be securely fixed in the flock hole 13 and the gap can be reduced. Moreover, in order to prevent the flat wire from coming out of the flocked hole 13, the total length of the portions protruding from both sides of the flocked hole 13 is preferably 0.3 to 0.6 mm.

The hole cross-sectional area of the flocked hole 13 is preferably 1.6 mm ² or less, and more preferably 1.4 mm ² or less. When the hole cross-sectional area is 1.6 mm ² or less, the side edge hair bundle 11a becomes thin, so that the flexibility is improved and the penetration into the tooth neck is further improved.
In the case of the present embodiment in which the flock hole 13 is circular in order to obtain the above-mentioned hole cross-sectional area, the diameter of the flock hole 13 in which the side edge follicle bundle 11a and the central follicle bundle 11b are flocked is 1.4 mm or less. Is preferable, and it is more preferable that it is 1.3 mm or less.
Moreover, it is preferable that the diameter of the flock hole 13 is more than the minimum diameter which can be produced, and it is more preferable that it is 1.0 mm or more at the point which suppresses the excessive bending of a hair | bristle bundle and a hair loss feeling.

As shown in FIG. 4 (a), when brushing with the scrub method using a conventional toothbrush 100 in which the bristle bundle 11 has a uniform bristle length, when the bristle bundle 11 is pressed against the tooth surface C, The hair bundles 11 support each other. Therefore, the hair bundle 11 is difficult to bend and the penetration of the hair tip into the tooth neck is low.
On the other hand, in the toothbrush 1 of this embodiment, the bristle length of the center bristle bundle 11b is shorter than the bristle length of the side bristle bundle 11a, and there is a space between the side bristle bundles 11a and 11a on the central bristle bundle 11b. Therefore, when brushing teeth by the scrub method, as shown in FIG. 4 (b), the side edge hair bundles 11a can be restrained from supporting each other, and the side edge hair bundles 11a are easily bent. Entry into the cervical region is increased.
In addition, since the side bristle bundle 11a is bent and opened, the central bristle bundle 11b is easily brought into contact with the tooth surface C, so that the cleaning ability of the tooth surface C is improved. Furthermore, when the central bristle bundle 11b abuts on the tooth surface C, the head portion 10 can be supported and the distance from the tooth surface C to the head portion 10 can be made constant. Thereby, it is possible to clean the tooth surface C and allow the side edge hair bundle 11a to enter the tooth neck in a stable state.
From the above, the toothbrush 1 of the present embodiment has high cleaning performance for the tooth neck and the tooth surface, and is excellent in the feeling of use at the time of cleaning the tooth neck and the tooth surface.

Moreover, in the toothbrush 1 of this embodiment, since the center bristle bundle 11b is lower in hair length than the side edge bristle bundle 11a, when the dentifrice is put on the tip of the central bristle bundle 11b, the dentifrice is used. It becomes easy to hold. Therefore, the dentifrice can be used without waste and foaming is improved.
Moreover, in the toothbrush 1 of this embodiment, by adjusting the height difference between the bristle length of the side bristle bundle 11a and the bristle length of the central bristle bundle 11b, the cleaning property of the tooth neck and the cleaning property of the tooth surface are improved. The balance can be changed easily.

In addition, this invention is not limited to the said embodiment.
The shape of the flock hole 13 is not particularly limited, and may be, for example, a circle, an ellipse, or a rectangle.
The arrangement of the flock holes 13 need not be a lattice arrangement, and may be a staggered arrangement, an asymmetric arrangement, or any other arrangement. The arrangement of the flock holes 13 need not be symmetric with respect to the center line M.
Moreover, the center area | region 12b does not need to be rectangular shape. However, the shape of the central region 12b is determined by the arrangement of the flock holes 13 adjacent to the central region 12b. When the arrangement of the flock holes 13 is asymmetric with respect to the center line M, the central region 12b has a complicated shape that is not line symmetric.
The toothbrush of the present invention may be used as a brush for an electric toothbrush. Even if the toothbrush of the present invention is used for a brush for an electric toothbrush, the cleaning performance of the tooth neck and the tooth surface is high, and the usability at the time of cleaning the tooth neck and the tooth surface is excellent.

(Examples 1-15, Comparative Examples 1-5)
A toothbrush in which the side edge hair bundle, the center hair bundle, and the tip hair bundle were planted on the head portion was produced. Tables 1 to 4 show the diameters of the flock holes in which the hair bundles are flocked, the types of hairs (in the table, “ST” means tapered hairs), and the average hair length. In addition, flocking holes are provided so that L ₁ / L ₂ × 100 (%) is 35 to 75% and L ₃ / L ₄ × 100 (%) is 25 to 50%. 5 mil.

About the toothbrushes of Examples 1 to 11 and Comparative Examples 1 to 5, the dental plaque removal rate of the tooth neck and the tooth surface, the feeling of use at the time of cleaning the tooth neck and the tooth surface were evaluated by the methods described below. . The evaluation results are shown in Tables 1-3.
Moreover, about Example 2,3,12,13,14,15, the hair opening durability was evaluated. The evaluation results are shown in Table 4.

[Dial plaque removal rate]
The removal rate of artificial plaque applied to the teeth of the jaw model was measured using a brushing machine manufactured by Lion Corporation. Artificial plaque is applied to the first molar of the lower jaw and the buccal side, and using the toothbrushes of each example and each comparative example, brushing is performed under the brushing conditions (brushing force = 200 g, stroke = 20 mm, speed = 40 mm / second). A test was conducted. Then, the area of the part where the artificial plaque was removed was measured by image analysis for the tooth neck and the tooth surface, and the plaque removal rate was (plaque removal area / total neck area) × 100 (%) Obtained from the equation.
[Usage feeling]
Seven testers used the toothbrushes of each of the examples and comparative examples for 7 days, and evaluated the feeling of use of the tooth neck and the tooth surface when brushed by sensory evaluation. Evaluation was made into 7 steps of 1 to 7 points, and the higher the score, the better the usability.
[Drilling durability]
The width of the flocked part of the flocked group flocked on the head (full width at the tip of the group of hairs perpendicular to the handle longitudinal direction) before and after the predetermined number of times (50,000 times) of brushing with the model durability tester ) Change amount expressed as a percentage of the “hair opening rate”. The part to be measured at this time was measured for the outermost hair bundle and evaluated according to the following criteria.
Opening ratio (%) = [(Flocked part width after brushing−Flocked part width before brushing) / (Flocked part width before brushing)] × 100
5 points: less than 40% 4 points: 40% or more and less than 50% 3 points: 50% or more and less than 60% 2 points: 60% or more and less than 70% 1 point: 70% or more

[Comprehensive evaluation]
In Tables 1 to 3, the overall evaluations determined from the plaque removal rate and the feeling of use are as follows.
A: Dental neck removal rate of 80% or more, dental plaque removal rate of 70% or more, and a feeling of use on the tooth neck and tooth surface of 4 points or more.
○: The plaque removal rate of the tooth neck is 70% or more and less than 80%, the plaque removal rate of the tooth surface is 60% or more and less than 70%, and the feeling of use on the tooth neck and tooth surface is 4 points or more. Things.
X: Other than the above.
In Table 4, the comprehensive evaluation determined from the above-mentioned plaque removal rate and fleece durability is as follows.
A: Hair opening durability of 4 points or more and tooth neck plaque removal rate of 80% or more.
◯: Hair opening durability of 3 points or more and tooth neck plaque removal rate of 70% or more.

The toothbrushes of Examples 1 to 11 in which the bristle length of the central bristle bundle is 90% or less of the bristle bristle bundle and the tip bristle bundle have a high plaque removal rate with respect to both the tooth neck and the tooth surface. The feeling of use was excellent. In particular, the toothbrush of Example 3 in which the bristle length of the central bristle bundle is 70% of the bristle length of the side bristle bundle and the tip bristle bundle has a particularly high plaque removal rate at the cervical part and excellent usability. .
In contrast, the toothbrush of Comparative Example 1 in which the bristle length of the central bristle bundle is equal to the bristle length of the side bristle bundle and the tip bristle bundle, the bristle length of the central bristle bundle is higher than the bristle length of the side bristle bundle and the tip bristle bundle. The long toothbrush of Comparative Example 2 had a low plaque removal rate with respect to both the tooth neck and the tooth surface, and the usability during cleaning of the tooth neck was impaired.
Comparative Example Comparative Example 3, _{L 1} L ₃ is 69% of _{L 4} is 23% of _{L 2} 5 was insufficient feeling during cervical cleaning.
In Comparative Example 4 in which L ₁ was 81% of L _2, the feeling of use at the time of cleaning the tooth neck was insufficient.

Further, from the results of Example 1, Example 2 and Example 4, as the diameter of the flock hole of the central hair bundle becomes smaller, the plaque removal rate of the cervical part is improved, and the usability at the time of cleaning the cervical part is improved. Was found to improve.
In addition, from the results of Example 1, Example 5 and Example 6, by making the central hair bundle straight hair, the plaque removal rate of the tooth surface is improved, and the usability at the time of tooth surface cleaning is improved. There was found.
In addition, from the results of Examples 2, 3, 12, 13, and 14, the hair opening durability was lowered as the hair length of the central hair bundle was shortened. In the comprehensive evaluation in consideration of the dental neck plaque removal rate, Examples 3, 12, and 13 in which the hair length of the central hair bundle is 30 to 70% of the hair length of the side edge hair bundle and the tip hair bundle are good results. showed that.
Further, from the results of Example 15 and Example 3, when a double-core tapered hair is used for the side edge hair bundle, the durability and tooth of the tooth neck portion are more durable than a tapered hair made of a single material. It was found that the plaque removal rate was high. It is considered that the taper bristles have a double-core structure, so that the rigidity is higher and the scraping power of the side edge hair bundle is improved.

DESCRIPTION OF SYMBOLS 1 Toothbrush 10 Head part 11 Hair bundle 11a Side edge hair bundle 11b Central hair bundle 11c Tip hair bundle 12 Flocked area 12a Side edge area 12b Central area 13 Flocked hole 20 Handle part C Tooth surface M Center line

Claims (5)

In a toothbrush comprising a head portion in which a plurality of flocked holes are formed, a hair portion in which a plurality of bristles are bundled in the flocked hole, and a handle portion extended to the head portion,
The side edge hair bundles adjacent to each other across the center line of the flocked region from the base end of the head portion to the tip end in a region of 35 to 75% of the length of the flocked region from the base end to the tip end of the head portion. Are a pair of side edge hair bundle groups formed by being planted at a distance of 25 to 50% of the length in the direction perpendicular to the center line in the hair transplant region, and the pair of side edge hair bundle groups And a central hair bundle group formed by flocking the central hair bundle,
Hair length of the central tuft state, and are 90% or less of Hair length of the side edge tuft,
A toothbrush characterized in that no bristle bundle is implanted between the central bristle bundle group and the handle portion . The toothbrush of Claim 1 whose ratio of the total number of the said center hair | bristle bundle is 7 to 17% with respect to the total number of the hair | bristle bundle planted by the said head part. The toothbrush according to claim 1 or 2 , wherein a flocked hole in which the side edge bristles and the central bristles are flocked has a hole cross-sectional area of 1.6 mm ² or less. The toothbrush according to any one of claims 1 to 3, wherein at least a part of the hair of the side edge hair bundle is a hair whose diameter gradually decreases toward the hair tip. At least a part of the hair of the side edge hair bundle has a multi-core structure including a core part and at least one or more sheaths provided outside the core part, and gradually toward the hair tips. The toothbrush according to any one of claims 1 to 4, wherein the toothbrush is a polyester bristle having a reduced diameter.

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