Patent Application
20170319309
The present invention relates to an interdental cleaning device for cleaning interdental spaces.
An interdental cleaning device (interdental brush) used widely includes a core portion composed of twisted two thin metal wires; and a brush portion having filaments fixed between the two thin wires. However, the metal wires tend to easily hurt the teeth and gum when inserted into interdental spaces. Thus, various other interdental cleaning devices are proposed and commercialized, which have a synthetic resin core portion; a cleaning soft portion that is made of an elastomer and molded to cover a front end portion of the core portion; and a gripping portion provided at the rear end of the core portion, in which the core portion and the cleaning soft portion form a cleaning portion to be inserted between teeth (see, for example, Patent Literature 1).
When the interdental cleaning device described in Patent Literature 1 is used to clean spaces between molar teeth, it must be inserted obliquely into the spaces between the molar teeth because the cheek obstructs its insertion from the cheek side. Therefore, for example, as illustrated in
Unfortunately, since the synthetic resin is less flexible than metal wires, the interdental cleaning device can fail to be inserted between molar teeth, depending on how the interdental cleaning device is in contact with the molar teeth or how the user applies a force, so that the cleaning soft portion or the synthetic resin core portion may break or buckle due to the interference from the molar teeth.
It is an object of the present invention to provide an interdental cleaning device that is configured to reduce the possibility of breakage in the process of insertion between molar teeth.
The present invention is directed to an interdental cleaning device for being inserted into an interdental space to clean the interdental space, the interdental cleaning device including: a rod-shaped core portion; and a soft portion being softer than the core portion and covering an outer surface of at least a part of the core portion, the part including a core front end as a front end of the core portion, wherein the soft portion has a partial length of 0.5 mm or more between the core front end and a soft front end as a front end of the soft portion. Taking into account significant figures, 0.5 represents a number in the range of 0.45 to 0.54. Therefore, it is meant that the partial length of the soft portion between the core front end and the soft front end as the front end of the soft portion is substantially 0.45 mm or more.
According to these features, the region between the core front end and the soft front end as the front end of the soft portion has no core portion and is flexibly bendable. Therefore, when the user intends to insert the interdental cleaning device between molar teeth, the user can easily direct the front end of the interdental cleaning device to the space between the molar teeth because the user can deform and bend the non-core portion of the soft portion by further pushing the interdental cleaning device from the position where the front end is in contact with the molar tooth surface. When the user further pushes the interdental cleaning device with its front end facing to the space between the molar teeth, the core front end is directed to the space between the teeth by the front end facing to the space between the teeth, before the core front end comes into contact with the tooth surface through the soft portion, so that the interdental cleaning device is guided and smoothly inserted between the teeth. As a result, the force applied by the user to push the interdental cleaning device is converted into a driving force in the direction of insertion of the interdental cleaning device, which can reduce the possibility of application of excessive pressure to the interdental cleaning device and thus reduce the possibility of breakage of the interdental cleaning device in the process of inserting the interdental cleaning device between the molar teeth.
The soft portion preferably has a partial length of 2.0 mm or less between the core front end and the soft front end.
If the soft portion has a partial length of more than 2.0 mm between the core front end and the soft front end, the soft portion may be bent into a U-shape when it is pushed with its front end being in contact with the molar tooth, so that the core front end may fail to be directed to the interdental space, which may make it difficult to direct the interdental cleaning device to the interdental space. However, when the soft portion has a partial length of 2.0 mm or less between the core front end and the soft front end, the soft portion is less likely to be bent in a U-shape, so that the soft portion can easily guide the interdental cleaning device to the interdental space.
The soft portion preferably has a partial length of 0.7 mm or more between the core front end and the soft front end.
When the soft portion has a partial length of 0.7 mm or more between the core front end and the soft front end, the soft portion can more effectively guide the interdental cleaning device to the interdental space, so that the possibility of breakage of the interdental cleaning device can be more reduced in the process of inserting the interdental cleaning device between molar teeth, than when the soft portion has a partial length of less than 0.7 mm between the core front end and the soft front end.
In addition, the soft portion preferably has a partial length of 1.5 mm or less between the core front end and the soft front end.
When the soft portion has a partial length of 1.5 mm or less between the core front end and the soft front end, the possibility that the soft portion will be bent into a U-shape and fail to be directed to the interdental space can be more reduced, so that the soft portion can more easily guide the interdental cleaning device to the interdental space, than when the soft portion has a partial length of more than 1.5 mm between the core front end and the soft front end.
In addition, the soft portion is preferably an elastomer with a Shore hardness of A30 to A50.
According to this feature, the soft portion has a hardness suitable for the guidance of the interdental cleaning device when the soft portion at the front end of the interdental cleaning device is directed to the interdental space.
In addition, a ratio of the partial length of the soft portion between the core front end and the soft front end to a thickness of the soft portion at the core front end is preferably in a range of 0.5 to 2.5.
According to this feature, the non-core portion of the soft portion can be easily deformed and bent, so that the front end of the interdental cleaning device can be easily directed to the interdental space.
In addition, the ratio of the partial length of the soft portion between the core front end and the soft front end to the thickness of the soft portion at the core front end is preferably in the range of 0.7 to 2.1. Taking into account significant figures, 0.7 represents a number in the range of 0.65 to 0.74, and 2.1 represents a number in the range of 2.05 to 2.14. Preferably, therefore, the ratio of the partial length of the soft portion between the core front end and the soft front end to the thickness of the soft portion at the core front end is substantially in the range of 0.65 to 2.14.
According to this feature, the non-core portion of the soft portion can be easily deformed and bent, so that the front end of the interdental cleaning device can be easily directed to the interdental space.
In addition, the soft portion preferably has a plurality of protrusions that are formed to protrude in directions crossing an axial direction of the core portion, and at least one of the protrusions is preferably formed in a region between the core front end and the soft front end.
According to these features, when the front end of the interdental cleaning device is directed to the interdental space, the protrusion will come into contact with the tooth surface to inhibit adhesion of the front end surface of the interdental cleaning device to the tooth surface. As a result, the front end of the interdental cleaning device directed to the interdental space can easily slip into the interdental space.
In addition, the soft portion preferably has a plurality of protrusions that are formed to protrude in directions crossing an axial direction of the core portion, and a longitudinal distance (e.g., a distance Lx in
According to these features, when the front end of the interdental cleaning device is directed to the interdental space, the protrusion will come into contact with the tooth surface to inhibit adhesion of the front end surface of the interdental cleaning device to the tooth surface. As a result, the front end of the interdental cleaning device directed to the interdental space can easily slip into the interdental space.
In addition, among the protrusions, a protrusion at a position closest to the soft front end is preferably formed entirely in a region between the core front end and the soft front end.
According to this feature, when the front end of the interdental cleaning device is directed to the interdental space, the protrusion will come into contact with the tooth surface to further inhibit adhesion of the front end surface of the interdental cleaning device to the tooth surface. As a result, the front end of the interdental cleaning device directed to the interdental space can more easily slip into the interdental space.
In addition, the interdental cleaning device preferably further includes a handle portion being connected to a rear end of the core portion and having a flat plate shape, wherein among the protrusions, a protrusion at a position closest to the soft front end preferably protrudes in a direction crossing an axial direction of the core portion and being along an in-plane direction of the handle portion.
According to these features, when the user grips the interdental cleaning device by pinching the handle portion between the thumb and index finger, the protrusion at a position closest to the soft front end can be positioned to protrude in the horizontal direction. When the user grips the interdental cleaning device in this position and inserts it between teeth, the protrusion directed in the horizontal direction will come into contact with the tooth side surface. As a result, the front end surface of the interdental cleaning device is less likely to adhere to the tooth so that the front end of the interdental cleaning device can easily slip into the interdental space.
The features of the interdental cleaning device described above can successfully reduce the possibility of breakage of the interdental cleaning device in the process of insertion into spaces between molar teeth.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in the respective drawings, the same elements are denoted by the same reference signs, and a repeated description thereof will be omitted.
The interdental cleaning device 1 illustrated in
The soft portion 20 includes an elastic material, such as an elastomer, having a Shore hardness of A30 to A50. Examples of the elastomer that can be used to form the soft portion 20 include thermoplastic elastomers such as styrene elastomers, olefin elastomers, and polyamide elastomers; and thermosetting elastomers such as silicone rubbers, urethane rubbers, fluororubbers, natural rubbers, and synthetic rubbers. Particularly in view of safety of the material for use in oral cavity, the soft portion 20 preferably includes a polyolefin or styrene thermoplastic elastomer or a silicone rubber. Also in view of compatibility with the synthetic resin material used to form the base portion 10, the soft portion 20 more preferably includes a polyolefin or styrene thermoplastic elastomer, for example, when the base portion 10 includes polypropylene as described below.
As illustrated in
The base portion 10 is made of, for example, a mixture of fibers and synthetic resin. As illustrated in
The handle base portion 11 is formed in a flat slender plate shape. Alternatively, the handle base portion 11 may be formed in any shape other than the flat slender plate shape, such as a rod shape with a circular, elliptical, polygonal, or other cross-sectional shape, as long as it has a shape for facilitating the gripping by hand and the interdental cleaning. The front end portion of the handle base portion 11 becomes narrower in width toward the core base portion 12 side, and is smoothly connected to the core base portion 12. The handle base portion 11 may have any dimensions capable of facilitating the gripping by hand and the interdental cleaning. For example, the handle base portion 11 has a length L1 of 10 mm to 25 mm, a width W1 of 3.0 mm to 10 mm, and a gripping portion thickness t1 of 0.8 mm to 5.0 mm.
In view of handleability, a length L2 of the exposed portion 12a is typically from 10 mm to 50 mm, preferably from 10 mm to 25 mm, which is from the end of the rounded portion (curved portion) of the front end side surface of the handle base portion 11 narrower in width to the base end of the soft portion 20. In view of the ability to clean the space between teeth, a length L3 of the soft portion 20 is, for example, from 9 mm to 22 mm.
In view of insertability into the space between teeth, the tapered surface makes an angle θ of 0.2° to 1.8° with the central line of the core base portion 12. The front end portion of the core main body 12b has a diameter of 0.3 mm to 0.6 mm. The base end portion of the core main body 12b has a diameter of 0.8 mm to 2.0 mm. The soft portion 20 (cleaning portion 2) has a soft front end P2 as its front end. The curved surface end of the soft front end P2 has a diameter D of 0.5 to 1.2 mm, preferably 0.5 to 1.0 mm, more preferably 0.5 to 0.8 mm. The core main body 12b is so formed that its front end portion extending at least 5 mm from its front end is reliably insertable between teeth.
In this case, the angle θ of the tapered surface of the core base portion 12 is constant over the entire length of the core base portion 12. Alternatively, however, the angle θ may be continuously or gradually reduced toward the front end side of the core base portion 12. In addition, the exposed portion 12a may be formed in a shaft shape with a constant diameter over its entire length, and only the core main body 12b may be gently tapered to decrease in diameter toward the front end side. Alternatively, the exposed portion 12a may also be omitted, and the core main body 12b may be connected directly to the handle base portion 11.
If the soft portion 20 covering the surface of the core base portion 12 is too thick, the core main body 12b must have a small diameter for insertion between teeth. This is not preferred because not only the cleaning portion can have significantly reduced stiffness during the insertion between teeth but also Karman vortices can easily form and have a significant effect during the molding of the cleaning portion 2. On the other hand, if the soft portion 20 is too thin, it may be impossible to charge the elastomeric material until the base end portion of the cleaning portion 2 can be completed. Therefore, the thickness of the soft portion 20 is preferably from 0.1 mm to 0.3 mm.
The soft guide portion 22 preferably has a thickness (diameter) A of, for example, about 0.7 mm to about 1.0 mm at the position of the core front end P1, and preferably has a ratio (Lp/A) of the length Lp to the thickness A of about 0.5 to about 2.5, more preferably about 0.7 to about 2.1 (substantially 0.65 to 2.14 taking into account significant figures).
In a preferred mode, therefore, the soft portion has a plurality of protrusions that are formed to protrude in directions crossing the axial direction of the core portion, in which at least one of the protrusions is formed in a region between the core front end and the soft front end.
According to these features, when the front end of the interdental cleaning device is directed to the space between molar teeth, the protrusion can come into contact with the surface of the molar teeth, so that the front end surface of the interdental cleaning device is less likely to adhere to the surface of the molar teeth. As a result, the front end of the interdental cleaning device directed to the space between the molar teeth can easily slip into the space between the molar teeth.
The cross-sectional area S of the base end of the protrusion 21a, the length B and number of the protrusions 21a, and the pitch at which the protrusions 21a are arranged may be selected freely. In view of the ability to be molded or the cleaning ability, the cross-sectional area S of the base end of the protrusion 21a is preferably from about 0.03 mm2 to about 1.5 mm2, the length B of the protrusion 21a is preferably from about 0.1 mm to about 2.0 mm, the number of the protrusions 21a is preferably from 20 to 100, and the protrusions 21a are preferably arranged at a pitch of 0.1 mm to 1.5 mm. In this example, the protrusions 21a used have a conical shape. Alternatively, protrusions having a tapered axially-flat plate shape may also be used. In addition, the cross-section of the protrusions 21a may have a circular shape or any other shape such as an ellipse or a polygon.
Referring to
Examples of synthetic resin materials that can be used to form the base portion 10 include polypropylene (PP), polybutylene terephthalate (PBT), polyethylene, polyethylene terephthalate, polycyclohexylene dimethylene terephthalate, saturated polyester resins, polymethyl methacrylate, cellulose propionate, polyurethane, polyamide, polycarbonate, ABS (acrylonitrile-butadiene-styrene) resins, and other thermoplastic synthetic resin materials. In particular, polypropylene (PP) and polybutylene terephthalate (PBT) are preferred, which can prevent the base portion 10 from buckling. Polypropylene is most preferred, which can be molded at low temperatures, can reduce cycle time and improve productivity, and can be processed with a lower thermal load on the molding facility.
The fibers added to the synthetic resin material for forming the base portion 10 may be, for example, glass fibers, carbon fibers, or aramid fibers. The content of the fibers depends on the synthetic resin material for forming the base portion 10. Basically, the base portion 10 with a fiber content of less than 12% by weight can easily bend so that the cleaning portion 2 can be difficult to insert between teeth, and the base portion 10 with a fiber content of more than 35% by weight can make the cleaning portion 2 buckle easily. Therefore, the content of the fibers in the base portion 10 is preferably 12% by weight or more and 35% by weight or less, more preferably 15% by weight or more and 35% by weight or less, even more preferably 20% by weight or more and 30% by weight or less. Specifically, when polypropylene (PP) is used as the synthetic resin material, the fiber content is preferably 15% by weight or more and 35% by weight or less, and when polybutylene terephthalate (PBT) is used as the synthetic resin material, the fiber content is preferably 12% by weight or more and 35% by weight or less.
The longitudinal direction of the fibers is preferably oriented in a direction along the longitudinal direction of the base portion 10. This feature makes it possible to improve the bending strength or axial buckling strength of the base portion 10 and to effectively prevent the core base portion 12 from bending or buckling during use of the interdental cleaning device 1. When the fibers are oriented in the longitudinal direction of the base portion 10, the connecting portions 13 also have the fibers oriented along the longitudinal direction of the base portion 10, so that the interdental cleaning devices 1 molded in parallel can be cleanly cut off from each other at the connecting portions 13 by turning the interdental cleaning device 1 about the connecting portions 13 in such a manner that the adjacent interdental cleaning devices 1 are placed over each other. The addition of the fibers also improves the dimensional stability of the base portion 10 and increases the strength and stiffness of the base portion 10 so that its deformation is prevented. The fibers can also raise the thermal deformation temperature of the core base portion 12, which makes it possible to effectively prevent the core base portion 12 from being softened and deformed by heat from the elastomeric material during the molding of the soft portion 20. The fibers can also increase the strength and stiffness, which makes it possible to prevent the core base portion 12 from being deformed by the elastomeric material injection pressure and to effectively prevent poor molding of the soft portion 20.
In addition, the protrusion 21a formed in the soft guide portion 22 can reduce the friction between the soft guide portion 22 and the molar tooth surface. If the protrusion 21a is not formed in the soft guide portion 22, the side surface of the bent soft front end P2 may adhere to the molar tooth surface, so that the soft front end P2 may resist slipping into the interdental space. However, the interdental cleaning device 1 having the protrusion 21a formed in the soft guide portion 22 allows the side surface of the bent soft front end P2 to resist adhesion to the molar tooth surface. As a result, the soft front end P2 facing toward the space between molar teeth can easily slip into the space between them.
In this process, the soft portion 20 and the protrusions 21a formed in the soft portion 20 clean the interdental space. As described above, the soft guide portion 22 facing toward the space between molar teeth functions to guide the insertion of the interdental cleaning device 1, so that the cleaning portion 2 formed with the soft portion 20 is smoothly inserted into the interdental space. As a result, the possibility of breakage of the interdental cleaning device 1 can be reduced in the process of inserting the cleaning portion 2 into the space between molar teeth.
In the example shown above, the protrusion 21a is formed in the soft guide portion 22. Alternatively, the protrusion 21a may be absent in the soft guide portion 22. Even in such a case, the soft guide portion 22 with a length Lp of 0.5 mm or more can guide the cleaning portion 2 into the interdental space, so that the possibility of breakage of the interdental cleaning device 1 can be reduced in the process of inserting the cleaning portion 2 into the space between molar teeth.
In addition, the handle portion 3 (handle base portion 11) does not always have a flat plate shape. Alternatively, it may have, for example, a columnar shape such as a cylindrical shape or a polygonal prism shape. However, when the handle portion 3 has a flat plate shape, the user can grip the handle portion 3 with the thumb and index finger as illustrated in
<Evaluation Test>
Next, a test for evaluating the interdental cleaning device 1 will be described. A plurality of samples of the interdental cleaning device 1 shown in
Samples with the length Lp ranging from 0.5 mm to 2.0 mm were prepared in Examples 1 to 5. Samples with the length Lp being less than 0.5 mm were prepared in Comparative Example 1, and samples with the length Lp exceeding 2.0 mm were prepared in Comparative Examples 2 and 3. For reference purposes, the base portion 10 was made of an elastomer, and samples of the interdental cleaning device 1 with the same shape were made of only the elastomer and then also subjected to the evaluation test. Specifically, the length Lp is 0.2 mm in Comparative Example 1, 0.5 mm in Example 1, 0.7 mm in Example 2, 1.0 mm in Example 3, 1.5 mm in Example 4, 2.0 mm in Example 5, 2.5 mm in Comparative Example 2, and 3.0 mm in Comparative Example 3, and samples with the same shape as the interdental cleaning device 1 were made of only the elastomer in Comparative Example 4.
In Example 2 (J2) shown in
The protrusion 21a closest to the front end is more preferably formed entirely in the soft guide portion 22, in other words, the longitudinal distance between the soft front end P2 and the junction rear end 212 of the protrusion 21a closest to the front end is more preferably equal to or less than the length Lp. In the case where the protrusion 21a closest to the front end is formed entirely in the soft guide portion 22, the protrusion 21a closest to the front end can come into contact with the molar tooth surface when the soft guide portion 22 is directed to the space between the molar teeth, so that the surface of the soft guide portion 22 can be prevented, with improved reliability, from adhering to the molar tooth surface.
In the examples shown above, one protrusion 21a is formed in the soft guide portion 22. Alternatively, two, three, or more protrusions 21a may be formed in the soft guide portion 22.
In the example of
Each sample was also subjected to an evaluation test in which the interdental cleaning device 1 was inserted between teeth under different conditions including three insertion angles R: 30°, 40°, and 50° and two insertion rates: 30 mm/min and 200 mm/min. The test was performed on three samples of each type (n=3). For example, three samples of Example 1 were prepared for carrying out the test under each of six sets (in total) of conditions including insertion at a rate of 30 mm/min and an insertion angle R of 30°, 40°, or 50° and insertion at a rate of 200 mm/min and an insertion angle R of 30°, 40°, or 50°. Therefore, 18 samples of Example 1 were used in total. Similarly, 18 samples of each of other examples and comparative examples were used in the test.
The evaluation test was performed as follows. Using a compression tester, the soft front end P2 of the interdental cleaning device 1 was pushed, as illustrated in
Table 1 shows the test results at the insertion rate of 30 mm/min, and Table 2 shows the test results at the insertion rate of 200 mm/min. In Tables 1 and 2, the term “excellent” indicates that the interdental cleaning device 1 was neither broken nor deformed. The term “good” indicates that breakage of the interdental cleaning device 1, rupture of the soft portion 20, or any other breakage did not occur, but deformation of the interdental cleaning device 1 occurred. The term “unacceptable” indicates that breakage occurred such as breakage of the interdental cleaning device 1 or rupture of the soft portion 20.
When the insertion rate was 30 mm/min (Table 1), the test results obtained at insertion angles R of 30° and 40° were “excellent” for all of Examples 1 to 5. When the insertion rate was 200 mm/min (Table 2), the test results obtained at an insertion angle R of 30° were “excellent” for all of Examples 1 to 5. When the insertion rate was 30 mm/min (Table 1), the test results at an insertion angle R of 50° were “good” for Examples 1 and 5 and “excellent” for Examples 2 to 4. When the insertion rate was 200 mm/min (Table 2), the test results at an insertion angle R of 40° were “good” for Example 1 and “excellent” for Examples 2 to 5. When the insertion rate was 200 mm/min (Table 2), the test results at an insertion angle R of 50° were “good” for Examples 1 and 5 and “excellent” for Examples 2 to 4.
As a result, it has been found that in Examples 1 to 5, specifically, when the length Lp is in the range of 0.5 mm to 2.0 mm, “good” or “excellent” results are obtained at all insertion rates 30 mm/min and 200 mm/min and at all insertion angles R 30°, 40°, and 50° and that “excellent” results are obtained for all of Examples 1 to 5 particularly at an insertion rate of 30 mm/min (Table 1) and insertion angles R of 30° and 40° and at an insertion rate of 200 mm/min (Table 2) and an insertion angle R of 30°.
On the other hand, in Comparative Example 1 (Lp=0.2 mm) where the length Lp is shorter than that in Example 1 (Lp=0.5 mm), “unacceptable” results are obtained at all insertion angles R 30°, 40°, and 50° at both insertion rates 30 mm/min (Table 1) and 200 mm/min (Table 2). In Comparative Example 1, the soft portion was thin at the front end of the interdental cleaning device, so that the soft portion did not bend even when the front end came into contact with the molar tooth surface, and as a result, the interdental cleaning device broke without being guided into the interdental space when the pressure was applied from the compression tester in such a manner that the interdental cleaning device was pushed against the molar tooth.
However, in Examples 1 to 5 where the length Lp is 0.5 mm or more, when the pressure is further applied from the compression tester to the interdental cleaning device with the soft front end P2 being in contact with the curved corner surface of the second molar tooth 6 (
The test results have demonstrated that 0.5 mm or more about the length Lp in the interdental cleaning device 1 is a significant threshold value for achieving the object of reducing the possibility of breakage of the interdental cleaning device in the process of insertion into the space between molar teeth. In this regard, taking into account significant figures, 0.5 represents a number in the range of 0.45 to 0.54. Therefore, the length Lp should be substantially 0.45 mm or more in the interdental cleaning device 1 according to the present invention.
In Comparative Examples 2 and 3 where the length Lp was 2.5 mm or more and in Comparative Example 4 where the device was entirely made of the elastomer, the results were “unacceptable,” except that the results were “good” at an insertion rate of 30 mm/min and an insertion angle R of 30° in Comparative Example 2. Specifically, in Comparative Example 2, the results were “unacceptable” at an insertion rate of 30 mm/min and an insertion angle R of 40° or 50° and at an insertion rate of 200 mm/min and an insertion angle R of 30°, 40°, or 50°. In Comparative Examples 3 and 4, the results were “unacceptable” at all insertion rates and all insertion angles.
In Comparative Examples 2 and 3 where the length Lp was 2.5 mm or more and in Comparative Example 4 where the interdental cleaning device was entirely made of the elastomer, the soft portion had a long soft deformable portion at the front end of the interdental cleaning device, so that the front end of the soft portion was bent into a U-shape and did not face toward the interdental space, and as a result, the interdental cleaning device was not able to be inserted into the interdental space.
On the other hand, in Examples 1 to 5 where the length Lp was 2.0 mm, the interdental cleaning device 1 was inserted into the interdental space so that good test results were obtained. Therefore, it has been demonstrated that 2.0 mm or less about the length Lp in the interdental cleaning device 1 is a significant threshold value for achieving the object of easily inserting the interdental cleaning device into the space between molar teeth.
In Example 1 where the length Lp was 0.5 mm, the test results were “good” at an insertion rate of 30 mm/min and an insertion angle R of 50° and at an insertion rate of 200 mm/min and an insertion angle R of 40° or 50°. On the other hand, in Examples 2, 3, and 4 where the length Lp was 0.7 mm or more, “excellent” test results were obtained at all insertion rates 30 mm/min and 200 mm/min and all insertion angles R 30°, 40°, and 50°.
These test results have demonstrated that better results can be obtained when the length Lp is 0.7 mm or more in the interdental cleaning device 1 than when the length Lp is 0.5 mm or more.
In Example 5 where the length Lp was 2.0 mm, the test results were “good” at an insertion rate of 30 mm/min and an insertion angle R of 50° and at an insertion rate of 200 mm/min and an insertion angle R of 50°. On the other hand, in Examples 2, 3, and 4 where the length Lp was 1.5 mm or less, “excellent” test results were obtained at all insertion rates 30 mm/min and 200 mm/min and all insertion angles R 30°, 40°, and 50°.
These test results have demonstrated that better results can be obtained when the length Lp is 1.5 mm or less in the interdental cleaning device 1 than when the length Lp is 2.0 mm or less.
Five testers used the samples of Comparative Example 1 and Examples 1, 2, and 3 for 3 days to clean spaces between their front teeth. Subsequently, the testers determined whether or not the front end portion of each soft portion 20 broke. The test results are shown in Table 3. After use for 3 days by the 5 testers, the front end portion of the soft portion 20 broke to expose the core front end P1 in all the five samples of Comparative Example 1.
On the other hand, after use for 3 days by the 5 testers, no breakage occurred in the soft portion 20 of any of the samples of Examples 1, 2, and 3. This has demonstrated that when the length Lp is 0.5 mm or more, the interdental cleaning device 1 can have improved durability to cleaning between front teeth.
Table 4 shows the actually measured values of the thickness A, length B, thickness C, cross-sectional area S, and ratio (Lp/A) shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-229294 | Nov 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/081398 | 11/6/2015 | WO | 00 |
