Note: Descriptions are shown in the official language in which they were submitted.
12~317~ 5702 241
TOOTHBRUSH
Field of the Invention
The inven~ion relates to a ~oothbrush. The toothbrush
of the invention is effective in removing dental plaque, and
massaging the gums and not hurting them.
Description of the Prior Art:
In toothbrushes used in our daily lives, the material
for, and the thickness, length and implantation pattern, of the
bristles, and the material for and the shape of the handle are
determined selectively so that mainly the dirt on the surfaces of
the teeth, i.e. plaque or sordes can be efficiently removed.
It is known that a toothbrush has a gum massaging effect
in addition to the plaque removing effect. Komori et al (Bulletin
of Japan Society of Dental Pathology, 20, 246-259, 1974) proved by
making experiments using monkeys that if the gums are massaged
with a toothbrush, gingivitis can be prevented.
In spite of the fact that a toothbrush has such a gum
massaging effect, regular toothbrushes commercially available at
present are rarely designed so as to improve their gum massaging
effect. There are no other toothbrushes designed with the
intention, if any, of improving the gum massaging effects thereof
than a toothbrush the ends of the bristles of which are rounded to
prevent the gums from being hurt when the ends of the bristles
contact the same while the teeth are cleaned.
There are commercially-available toothbrushes for the
gum massaging purpose only, though the number of them in use is
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small. However, in these toothbrushes, very soft bristles are
implanted into the handle thereof so that the gums do not hurt
when the bristles are applied thereto. Rubber tips instead of
bristles are sometimes attached to the handle. Therefore, it is
impossible to expect such toothbrushes to have a sufficiently
large plaque removing effect. In view of the fact that plaque
directly causes not only caries but also gingivitis and alveolar
pyorrhea to occur, it can be said that these gum massaging tooth-
brushes are too ineffective to be used for the prevention of gin-
givitis.
Japanese Utility Model Laid-open No. 7676~/1976 dis-
closes a toothbrush in which bristles of an equal length having
small balls at the free end portions thereof are implanted into
the handle. In this type of toothbrush, the level of the force
required to insert the free end portions of the bristles into the
space between two adjacent teeth, in which it is the most diffi-
cult to remove the plaque, is substantially equal to that of the
force required to insert the free end portions of the bristles of
a conventional toothbrush into a similar space. Hence, the tooth-
brush disclosed in this publication has no special advantages inthis respect. Moreover, since the toothbrush has bristles of
equal length, the end of each bristle contacts a tooth in a simple
pattern. Accordingly, when a person, who moves a toothbrush in a
peculiar way while he cleans his teeth, uses this toothbrush, the
free ends of the bristles thereof would not contact some parts of
the teeth.
~X73171
65702-241
Summarv of the Invention
The present invention provides a toothbrush comprising a
handle, bores and bristle~ implanted into the bores, the bristles
having a diameter of from 6/1000 to 15/1000 of an inch and having
a free spherical end portion with a diameter of from 1.1 to 2.5
times the bristle diameter, the bristles being a mixture of longer
and shorter bristles wherein the length difference between the
longer and sh~rter bristles is withln the ~ange of fro~ 1 to 4 mm,
and wherein the lengths of 50~ or greater of the brlstles which
are ad~acent to any one arbitrary bri~tle are of a different
length to the arbitrary bristle.
Advantageous features of the inventlon will become
apparent from the following description of the preferred
embodiments taken in conjunction with ~he accompanying drawings.
Brief DescriPtion of the Drawinas
Figure 1 is a schematic side elevation of an embodiment
of the toothbrush according to the present invention; and
Figure 2 shows a bristle implantation pattern.
DescriPtion of the Preferred Embodiments
The toothbrush according to the present invention is
formed by implanting bristles which have spherical portions at ~he
free ends thereof, and which are made in not less than two
different length~, into a handle. The upper limit of the number
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of lengths of the bristles is not specially determined. If the
number of lengths of the bristles is increased so that the distri-
bution of the vario~s lengths thereof becomes as uniform as
possible, i.e., not one-sided, the possibility of partial abrasion
of the free ends of the bristles decreases.
Concerning the lengths of the adjacent bristles on the
same handle, it is preferable that the lengths of not less than
50% of a plurality of bristles which are adjacent to one arbitrary
bristle be different from that of the single bristle. If this
single bristle has a plurality of adjacent bristles of a length
equal to that thereof, the spherical portions of the bristles
contact one another, and the free end portions of the bristles are
inclined outward, so that the external appearance of the bristles
is spoiled.
The toothbrush according to the present invention has a
characteristic mode of arrangement of bristles, and spherical
portions are formed at the free ends of all of the bristles. The
difference between the length of the longest bristles and that of
the shortest bristles is in the range of 1-4 mm. It is necessary
that the number of lengths of these bristles be not less than two
or three.
Since the spherical portions formed at the free ends of
all of the bristles have the plaque rernoving effect, the tooth-
brush according to the present invention has a larger plaque
removing effect than a regular type of toothbrush. Since the
bristles in the toothbrush according to the present invention are
formed to various lengths the differences among which are within
the range of 1-4 mm, the free end portions thereof easily enter a
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space between two adjacent teeth, in which it is difficult -to
remove the plaque from the teeth, so that the plaque removing
effect of this toothbrush in such a s;pace is far greater than that
of a regular toothbrush. According to the present invention, the
free end of any one of the bristles always contact a tooth during
cleaning of the teeth irrespective of the magnitude of the force
applied to the bristles in motion, the kind of tooth (molar tooth,
premolar tooth, canine and incisor), and the position of the
tooth. Therefore, the plaque can be removed completely, so that a
uncleaned part of a tooth is not left.
The gum massaging effect of toothbrushes will now be
discussed. The bristles in a toothbrush, which have spherical
portions at the free ends thereof, and which are formed to an
equal length, contact the gums more softly than those of a regular
type of toothbrush, which are rounded at the free ends thereof and
formed to an equal length, but the former bristles hurt the gums
in some cases. It is considered that the reason why these
bristles hurt the gums is that the free ends of all the bristles
contact the gums. If spherical portions are formed at the free
ends of all the bristles with the bristles set to various lengths
as in the toothbrush according to the present invention, the free
ends of the bristles contact the gums with moderate pressure.
Therefore, even if the teeth are cleaned with a large force, the
gums do not hurt.
As described above, in the toothbrush according to the
present invention, it is necessary that the difference between the
length of the longest bristles and that of the shortest bristles
be within the range of 1-4 mm. When this difference is less than
1;~73171
1 mm, the bris~les extend substantially in the same manner as
those in a toothbrush, which are formed of an equal length. Such
bristles have neither a sufficient plaque removing effect nor a
sufficient gum massaging effect. When this difference exceeds 4
mm, the shortest bristles do not contact the teeth and gums.
Hence the bristles including such shortest bristles are substan-
tially identical with the implanted bristles of a reduced density.
Such bristles also have insufficient plaque removing and gum
massaging effects.
The present invention will further be described with
reference to the diameter of the bristles. The diameter of the
portion of a bristle which excludes its free end portion, i.e. a
non-spherical portion of a bristle is suitably around 6/1000-
15/1000 inch. When the diameter of the bristles is less than
6/1000 inch, the firmness of the bristles is lost, and the force
applied thereto during the cleaning of the teeth would not effec-
tively work as a plaque removing and gum massaging force. If the
tooth-cleaning force is then increased, the bristles would be bent
or the gums would be hurt. When the diameter of the bristles
exceeds 15/1000 inch, the firmness of the bristles becomes too
high, so that they contact the gums so as to cause discomfort. A
preferable diameter of the bristles is 6/1000-11/1000 inch.
On the other hand, the diameter (maximum diameter) of a
spherical portion at the free end of a bristle is suitably about
1.1-2.5 times the other portion thereof, and preferably about
1.2-2.0 times as large as the same. When the diameter of the
spherical portions of the bristles is less than 1.1 times that of
the other portions thereof, these bristles are substantially iden
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tical with the bristles having no spherical portions in a regular
type toothbrush, and do not have a sufficient practical effect.
When the diameter of the spherical portions exceeds 2.5 times that
of the other portions of the bristles, the free end portions of
the bristles are inclined outward to spoil the external appearance
thereof, and cause the commercial value of the toothbrush to
decrease greatly.
The spherical portion formed at the free end of the
bristle may also be made elliptical, nail-shaped, rectangularly-
shaped with the four corners rounded, square and trapezoidal. Thepattern of implanting bristles of not less than two or three
lengths is not specially li~ited. The bristles are preferably
implanted according to a pattern in which bristles of different
lengths are suitably distributed, i.e. a pattern in which the
bristles of the same or substantially the same length do not
locally gather.
The number of the bores into which the bristles are
implanted is generally 20-30, and the number of the bristles
implanted into one bore 30-60. These numbers do not constitute
the characteristics of the present invention. In addition, the
material for the bristles is not specially limited. The materials
of which the bristles in the conventional toothbrushes are made
can be used. The Nylon (TM) which is now widely used can also be
employed.
EMBODIMENT:
The toothbrush according to the present invention will
now be described with reference to its embodiment. The toothbrush
to be now described is only an example of the present invention.
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The lengths of the bristles, the diEference between the length of
the longest bristles and that of the shortest bristles, the dis-
tribution of the bristles of differen-t lengths and the implanta-
tion pattern of the bristles are not limited to those in the
embodiment which will now be described.
A toothbrush according to the present invention is shown
in schematic side elevation in Figure 1. Referring to Figure 1,
reference numeral 1 denotes a handle, 2 the bristles, and 3 the
spherical portions at the free ends of the bristles. As shown in
Figure 1, the bristles consist of bristles of larger and smaller
lengths. The distribution of the lengths of the bristles was as
follows.
Distribution of the lengths of the bristles:
Length of the bristlesDistribution (%)
g.o _ 9.9 10.1
10.0 - 10.9 58.3
11.0 - 11.9 30.3
12.0 - 12.4 1.3
Total: 100.0
20Length of the longest bristles: 12.4 mm
Length of the shortest bristles:9.0 mm
Difference between the lengths of
the longest and shortest bristles: 3.4 mm
The diameter of the portion of each bristle which is
other than the free end portion thereof was 8/1000 inch, and the
diameter of the spherical portion at the free end of each bristle
1.3-1.8 times that of the non-spherical portion thereof.
The implantation pattern of these bristles was as shown
in Figure 2. Referring to this drawing, reference numeral 4
317~
denotes bores into which the bristles are implanted, and the unit
of the measurements shown by smaller numerals is in millimeters.
The diarneter of each bore ~ was 1.~ mm, and forty
bristles were implanted into each bore. The distribution of the
lengths of the bristles, which is shown above, was determined with
respect to all of the bristles implanted into a total of thirty-
two bores.
Embodiment and Comparative Examples:
In accordance with the bristle implantation pattern of
Figure 2, the following four types of toothbrushes were prepared,
and a test was conducted, in which the magnitude of the force
applied to the teeth or gums was measured with respect to each
type of brush. The results are shown in Table 1.
Toothbrush A: The length of the bristles was set equal.
The corners of the free ends of the bristles were
rounded. The bristles had a diameter of 8/1000
inch.
Toothbrush B: Bristles of larger and smaller lengths were
implanted. The corners of the free ends of the
bristles were rounded. The bristles had a diameter
of 8/1000 inch.
Toothbrush C: Spherical portions were formed at the free ends of
the bristles. The length of the bristle was equal.
The portion of each bristle other than the
spherical portion thereof had a diameter of 8/1000
inch.
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Toothbrush D: Toothbrush according to the present invention
having the previously-mentioned distribution of
bristles.
Table 1
Average Value of( Pressure due( )
Type of load on measured to 1 kg load
toothbrush toothbrush pressure on toothbrush
A 1.13 kg 0.064 kg/cm2 0.057 kg/cm2
- B 1.17 0.083 0.071
C 1.18 0.109 0.092
D 1.20 0.135 0.113
Testing method:
A load (average load on toothbrush _ on Table 1) of
about 1 kg is applied to a toothbrush as a whole to read the value
(value of measured pressure b on Table 1) appearing on the pres-
sure-sensitive paper. This value represents the pressure applied
to the teeth and gums via the bristles. The pressure c due to the
1 kg load on the toothbrush is determined by dividing _ by _.
When the value c is large, it means that a high pressure
is applied to the teeth and gums with a smaller tooth-cleaning
force, and that a toothbrush having such a large value c has
excellent plaque removing and gum massaging effects. It is under-
stood from Table 1 that the toothbrush according to the present
invention is superior to the other toothbrushes.
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