Note: Descriptions are shown in the official language in which they were submitted.
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TOOTHBRUSH
TECHNICAL FIELD OF THE IN~rENTION
This invention relates to a toothbrush, in particular to a
toothbrush which can effectively and easily remove dental
plaque from the teeth, especially from molars, and from
the interdental spaces between the teeth.
Background of the Invention
According to research on dental diseases by the Ministry
of Health and Welfare in Japan in 1993, the average life
of a second molar is 45.8 years, that is, the second molar
l~ is lost l0.5 years earlier than other teeth which have an
average life of 56.3 years. It is now a matter of common
knowledge that the main reasons for losing teeth are
dental caries and periodontal disease. It is said that
dental caries and periodontal di5ease are caused mainly by
dental plaque that forms on the surfaces of teeth. Daily
brushing plays a major role in preventing the accumulation
of plaque and the o~currence of dental diseases caused by
such plaque. Periodic care by dental professionals also
plays a significant role in preventing dental disease.
One of the main methods for controlling plaque is brushing
with a toothbrush, and a variety of different types of
toothbrushes have been developed for this purpose.
It has been proposed heretofore to reduce the size of the
,30 brush head of the toothbrush in order to more easily reach
the second molars. When the body of the brush head is
,
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made smaller, the number of bristles must be
correspondingly reduced compared to the number of bristles
used in a conventional full-sized brush head. During
brushing, the reduced number of bristles bears the same
amount of pressure as that applied to the larger number of
bristles found in conventional toothbrushes. This tends
to cause increased bristle bending and shortens the useful
life of the toothbrush.
Japanese Laid-open Patent Application Hei 5-
168528(168528/93) discloses a toothbrush which has two
sections of bristles, the bristles of one section being
longer than the bristles of the other section. While such
a toothbrush may be more efficient in removing dental
plaque from molars, it is less efficient in removing
dental plaque from the other teeth. The presence of
unremoved dental plaque from the other teeth can lead to
dental diseases such as caries and periodontal disease.
On the other hand, it is easy to brush the flat surfaces
of the teeth with conventional toothbrushes having uniform
bristle length, but, since the sizes of the interdental
spaces vary according to their positions in the mouth,
such brushes do not effectively clean the interdental
spaces between the teeth.
SUMMARY OF THE INVENTION
The present invention provides a toothbrush which can
easily and effectively remove dental plaque from molars in
the deepest part in the mouth, from the surfaces of the
-
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other teeth and from the interdental spaces. This is
accomplished by providing a toothbrush whose brush head
comprises three bristle surfaces, none of which bristle
surfaces are parallel with respect to the surface of the
brush head from which the bristles extend.
In accordance with one aspect of the present invention
there is provided a toothbrush comprising a brush head, a
handle, and a neck portion connecting said brush head to
said handle;
said brush head comprising a plurality of rows of bristle
tufts, each of said rows of bristle tufts being oriented
in a direction generally perpendicular to the longitudinal
axis of said toothbrush;
the tips of the bristles of said bristle tufts being
arranged to provide three brush surfaces;
the first of said three brush surfaces being located
adjacent the free end of said brush head and extending
upwardly from said free end at an angle of from about 15~
to about 45~ with respect to said brush head to define a
first bristle peak;
said second brush surface extending downwardly from said
first bristle peak toward said brush head at an angle of
from about 15~ to about 45~ with respect to said brush
head;
, 30
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said third brush surface extending upwardly from said
second brush surface, at an angle of from about 5~ to
about 25~ with respect to said brush head, to a second
bristle peak, said second brush surface and said third
brush surface forming a bristle valley or bottom located
below said first bristle peak and said second bristle
peak, the ratio of the height of the bristles at said
first bristle peak to the height of the bristles located
at said bristle valley being from about 1.1 to about 1.4;
the difference between the height of the bristles at said
second bristle peak and the height of said bristles at
said first peak being less than about 2 mm.
It will be understood that the aforementioned rows of
bristle tufts may be either linear or arcuate in
configuration.
In a preferred embodiment, the brush head comprises six to
ten rows of bristle tufts.
In an even more preferred embodiment, the toothbrush of
the invention comprises six to ten rows of bristle tufts,
with said first bristle peak being located at the top of
the second or third row of bristle tufts and said bristle
valley being located at the third to fifth rows of bristle
tufts.
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DETAILED DESCRIPTION OF THE INVENTION
Bristles which are useful in the manufacture of
toothbrushes of the present invention can be made from
synthetic resins such as polybutylene terephthalate (PBT),
polyethylene terephthalate (PET), polyamide,
polypropylene, polyvinyl chloride (PVC), polyvinylidene
chloride, polyurethane, and mixtures thereof, animal hair
such as pig hair, or any other materials known in the art
for this purpose. In order to attain the aim of the
present invention to improve dental plaque removability,
especially on molars, comparatively stiff filaments, such
as polybutylene terephthalate (PBT) filaments are
preferred. The thickness of the filament in the case of
polybutylene terephthalate is pre~erably from about 0.15mm
to about 0.3mm. If the filament thickness is less than
about 0.15mm, the filament may not have sufficient bending
strength. If the filament thickness is greater than
0.3mm, the filament may be too stiff.
In the toothbrush of the present invention, the material
of the brush head, neck and handle is not particularly
restricted. Any materials known in the art for use in the
manufacture of conventional toothbrushes can be used.
Such materials include acrylonitrile-styrene copolymer
(AS); acrylonitrile-butadiene-styrene copolymer (ABS);
polypropylene (PP); cellulose derivatives such as
cellulose propionate; polyamide; polycarbonate-
polyethylene terephthalate copolymer (PC-PET3;
polycarbonate-acrylonitrile-butadiene-styrene copolymer
(PC-ABS~; polymethyl pentene; acrylic polymers such as
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polymethyl methacrylate (PMMA); polyacetal resins;
thermoplastic elastomers (olefinic polymers, styrenic
polymers, polyesters, polyurethanes, PVC polymers, etc.)
and the like.
In the toothbrush of the present invention, the brush head
includes a brush head body and a plurality of rows of
bristle tufts embedded in tuft holes formed in said body.
The toothbrush of the present invention has a handle for
holding tne brush when users brush their teeth. There is
a neck portion which joins the brush head and the handle.
The width of the neck is preferably less than the width of
the brush head and the handle, thereby imparting to the
toothbrush a certain degree of flexibility and making the
toothbrush easier to handle.
The brush head of the present invention preferably
comprises six to ten rows of bristle tufts, each of which
rows is oriented in a direction generally perpendicular to
the longitudinal axis of the toothbrush. If the brush
head has less than six rows of bristles, it is difficult
to provide a brush head of sufficient length for effective
removal of dental plaque. If the brush has more than ten
rows of bristles, the brush section becomes too long to
effectively brush the molars and ease of use decreases.
In the toothbrush of the present invention, it is
preferred that the first row and the second row of bristle
tufts closest to the free end of the brush head are made
up of two and three tufts of bristles respectively, and
the other rows (i.e., the third row to the last row at the
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end of the brush head body nearest the neck of the
toothbrush) are made up of four tufts of bristles arranged
in similar linear or arcuate configuration and are placed
symmetrically with respect to the center line of the brush
in the longit~ n~ 1 ~irection. Such an arrangement of the
bristle tufts makes the brush end of the toothbrush thin.
The term "brush end", which is also sometimes called the
"free end" of the brush head, refers to the end of the
toothbrush opposite the handle of the toothbrush.
In the present invention, the tips of the bristles on the
bristle tufts on the brush head must be arranged, as by
cutting, so that the resulting brush surfaces define three
planes. By cutting the bristle tips, the shape of the
brush surface characteristic of the present invention can
be easily formed. The three brush surfaces are made
continuing in the longitudinal direction of the brush
head.
The first brush surface is located adjacent the free end
of the brush head. The bristles at the brush end are
short and the bristles become longer toward the handle.
The first brush surface forms an angle of from about 15~ to
about 45~ to the brush head. The bristles form a first
brlstle peak, preferably at the second row or the third
row of bristles from the brush end. If the first brush
surface angle is less than about 15~, sufficient denta~
plaque removal from molars may not be attained. If the
angle of the first brush surface is greater than about 45~,
fitting of the toothbrush to the interdental spaces,
especially between molars, decreases. In a toothbrush
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having a compact brush head, the aforementioned first
bristle peak must be at the second row or the third row of
bristles from the brush end. If the first bristle peak is
in the first row, it is hard to provide the first brush
surface. If it is in the fourth row or beyond, dental
plaque removability on molars decreases because the first
bristle peak is too near to the center of the brush head.
The second brush surface extends from the first peak
defined by the first brush surface and declines toward
the handle at an angle of about 15~ to about 45~ , and
defines a bottom between the third row of bristles and
fifth row of bristles from the brush end. It will be
understood that the first brush surface joins or meets
the second brush surface at said first peak. This
arrangement im~roves fitting of the brush to interdental
spaces so as to remove dental plaque efficiently.
The third brush surface extends upwardly from the
aforementioned bristle valley or bottom to a second
bristle peak. Bristles of the third brush surface
become longer from the bristle valley as they approach
the second bristle peak, becoming longest at the
aforementioned second peak. The third brush surface
forms an angle of about 5~ to about 25~ with respect to
the surface of the brush head body. Consequently the
third brush surface continuously ascends from the
aforementioned bottom point to the second bristle peak.
Each of the three brush surfaces can be a flat surface
or a curved surface, and in the case of the curved
surface, the second brush surface and the third brush
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surface can have continuous curvatures. The term
"bristle valley" or "bristle bottom" refers to that part
of the brush where the first brush surface meets the
second brush surface.
s
Any cross section of the brush surfaces to the
transverse direction of the brush is preferably a
straight line parallel to the block head or an arc.
The ratio of the height of the bristles at the first
bristle peak E to the height of the bristles at bottom
point F must be l.l to l.4.
In the present invention, the difference in the height
of the bristles at the first bristle peak and the height
of the bristles at the second bristle pea~ is less than
about 2mm. Preferably, the bristles at the first
bristle peak and the bristles at the second bristle peak
have the same height. The difference in height between
bristles of the first and second bristle peaks and the
height of the bristles at the bottom point is preferably
between about 0.3mm to about 6mm, more preferably
between about l.Smm to about 3mm. If less than about
0.3mm, plaque removal from the molars in the deepest
part of the mouth is insufficient. If more than 6mm, it
is hard for bristles to contact every surface of the
other teeth, and plaque removal from the other teeth is
insufficient.
In the present invention, it is preferred to use stiffer
bristles for the first and second or first to third rows
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-- 10 --
of bristles. Similarly, it is preferred to use stiffer
bristles for the last row of bristles from the brush
end, i.e., the row of bristles nearest to the neck of
the toothbrush. Bristle stiffness may be controlled by
S using stiffer materials or thicker bristles or both.
This stiffening of specific bristles improves removal of
plaque and also prevents the spread of bristle tips
during use. Though the bristles between the first row
and the second or third row have the same thickness, the
last row of bristles from the bristle end included in
the third brush surface can have a different thickness.
Further it is preferred to use one color for the stiff
or thick bristles and another color for the other
bristles. The different colors make the toothbrush
colorful as well as aesthetically appealing, and also
draws attention to the spread of bristle tips after a
period of use. The diameter of the thick bristles is
preferably 5% to 30% greater than that of the other
bristles.
For the toothbrush of the present invention, it is
preferable that the first brush surface and the second
brush surface are symmetrically disposed about a plane
which bisects the first peak and which is transverse to
the brush head. This is accomplished when the angle of
the first brush surface with respect to the brush head
is equal to the angle of the second brush surface with
respect to the brush head.
Further, it is preferable that the length (C in Figure
1) of the third brush surface in the longitudinal
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direction of the brush head be longer than one half of
the entire bristle section length (D in Figure 1~.
The toothbrush of the present invention may be produced
by known methods using conventional high speed
toothbrush manufacturing machines such as the Sabolanski
ZT1-TC machine (Sabolanski Co. LTD). The toothbrush of
the present invention can easily and effectively remove
dental plaque on molars in the deepest part of the
mouth, in interdental spaces, on the inner surfaces of
teeth, etc. by providing the aforementioned three brush
surfaces.
EXAMPLES
~5
The invention will be more clearly understood with
reference to the following examples.
Toothbrush blanks in the shape of Figure 6, and
comprising a brush head, a neck and a handle were
manufactured by injection molding a blend of
polypropylene and EPDM. Measurements of the toothbrush
blanks were as follows: the whole length L: 188mm; the
brush head length G: 24.4mm; the brush head width H:
11.3mmi the maximum width, I, of the handle: 14mm; neck
portion width J: 5mm; and neck portion thickness K:
5.5mm. A toothbrush in accordance with the present
invention was produced by embedding polybutylene
terephthalate filaments of 0.2mm in diameter in the
brush head portion of the toothbrush blank.
_
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- 12 -
Referring now to Figure 1, there is shown therein a side
view of the brush head portion of a toothbrush according
to the present invention. In Figure 1, numerals 1, 2
and 3 indicate the first, second and third brush
surfaces, respectively, formed for example by suitably
cutting bristle tips. In this example, the three brush
surfaces are all in the form of flat planes. The
length, A, from the brush end 20 to the first bristle
peak 6 is 3.3mm; the length, B, from the first bristle
peak to the bottom point 22 is ~.lmm; and length, D, of
the bristle section is l9.9mm. The height, E, of the
bristles at the first bristle peak 6 is ll.Omm. The
height, F, of the bristles at bottom point 22, where
second brush surface 2 meets third brush surface 3, is
~.Omm.
Figure 2 is a plan view of the brush section shown in
Figure 1. The first row 25 of bristles is located
adjacent the brush end 40 and consists of two bristle
tufts 25a. The second row 26 of bristles consists of
three bristle tufts 26a and is slightly arcuate in
configuration. Each of third row 27 of bristles, fourth
row 28 of bristles, fifth row 29 of bristles, sixth row
30 of bristles, seventh row 31 of bristles, and eighth
row 32 of bristles consists of four bristle tufts. As
can be seen in Figure 2, all of rows 27-32 have a
somewhat arcuate configuration. The bristles comprising
the bristle tufts are made of polybutylene
terephthalate. The bristles in first row 25, second row
26, third row 27 and eighth row 32 are stiffened by
using bristles having a larger diameter than those of
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the other bristles. The diameter of the individual
bristles in the bristle tufts in bristle rows 25, 26 and
27, indicated in Figure 2 by circles with slanting
lines, is 0.2mm. The diameter of the individual
bristles comprising bristle tufts 5 in bristle row 32,
also denoted by circles with slanting lines, is 0.23mm.
The diameter of the individual bristles comprising the
bristle tufts in bristle rows 28-31 is 0.17mm. As }s
cLear from Figures 1 and 2, the bristles are cut so that
the first bristle peak 6 is located in the second row
from the brush end. The bottom point 22 is located in
the thlrd to fourth row from the brush end 40.
First brush surface 1, which is adjacent to brush end
1~ 4~, is oriented at an angle of about 31~ with respect to
the brush head. Third brush surface 3, which is nearest
to brush neck 12, is oriented at an angle of about 9~
with respect to the brush head. Second brush surface 2,
which is intermediate the first and third brush
surfaces, is oriented at an angle of about 26~ with
respect to the brush head. The ratio of the bristle
height, E, at peak 6 to the bristle height, F, at
bristle valley 22 is 11/9 - 1.22. The length, C,
measured parallel to the brush head, of the third brush
surface, is more than one half of the bristle section
length, D, also measured parallel to the brush head.
Figure 3 shows a side view of another embodiment of a
toothbrush of the present invention in which brush
. 30 surfaces 1, 2 and 3 are somewhat curved.
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General views of other toothbrushes according to the
present invention are shown in Figures 7 and 8, in which
the left side view is symmetrical with the right side
view.
For people who have wisdom teeth, the third permanent
molars, the toothbrush of the present invention provides
an effective means for brushing the wisdom teeth by the
presence of the first bristle peak. Figure 4 shows the
conformance of bristles to the surfaces of the third
molar as a result of the geometrical features of the
toothbrush of the present invention.
The spreading of bristle tips of the first bristle peak
6 following use can be prevented effectively when the
bristles at said peak have increased diameters or are
made from stiffer materials. Further, by the presence
of said first bristle peak 6, the toothbrush of the
present invention can brush maloccluded teeth more
effectively than conventional toothbrushes with flat
brush surfaces because the present toothbrush can easily
reach any surface of maloccluded teeth which are not
properly aligned. Figure 5 shows the confor~ance of
bristles of the first and second brush surfaces to
interdental spaces for the toothbrush of the present
invention. Figure 5 illustrates that the toothbrush can
easily contact and effectively brush the internal
interdental spaces of maloccluded incisors.
The toothbrush of the present invention is also
especially effective for brushing the internal surfaces
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- 15 -
of incisors, , i.e., the surfaces of the teeth facing
the tongue. When held parallel to the dentition, the
toothbrush of the present invention contacts the
internal surfaces of the incisors with the bristles of
at the second bristle peak, which effectively permits
the removal of dental plaque from these surfaces.
EFFECTS OF THE IN~ENTION
As the human dentition exhiblts a bow-shaped curvature,
not all of the bristles of conventional toothbrushes
with flat brush surfaces contact the teeth during
~rushing, and brushing is apt to ~e carried out by only
a specific portion of the bristle assembly. This leads
to uneven wear of the brush with concomitant shortening
of its useful life. Also, selected tooth surfaces are
not effectively contacted by conventional toothbrushes,
and, therefore, these surfaces are not effectively
brushed. In the toothbrush of the present invention,
the provision of three brush surfaces and the
geometrical and physical features of the brush surfaces
and bristles as herein described improves the fit of the
bristles to the dentition, increases the effectiveness
of brushing and prevents undesirable spreading and wear
of bristle tips during use.
~RIEF DESCRIPTION OF THE DRAWINGS
Figure l is a side view of the brush head of a
toothbrush in accordance with the present invention;
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Figure 2 is a plan view of the toothbrush of Figure 1
showing the rows of bristles;
Figure 3 is a side view of a brush head of another
embodiment of a toothbrush according to the present
invention, the brush surfaces being curved;
Figure 4 is a view of the toothbrush of Figure 1 when
being used in the brushing of molars;
Figure 5 is a view of the toothbrush of Figure 1 when
being used in the brushing of maloccluded teeth;
Figure 6(a) is a side view of a toothbrush blank of the
present invention;
Figure 6(b) is a plan view of the toothbrush blank of
Figure 6(a);
Figure 7(a) is a front view of another embodiment of a
toothbrush of the present invention;
Figure 7(b) is a side view of the toothbrush of Figure
7(a);
Figure 7(c) is a rear view of the toothbrush of Figure
7(a);
Figure 8(a) is a front elevational view of the
toothbrush of Figure 7~a);
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Figure 8(b) is a rear elevational view of the toothbrush
of Figure 7(a);
Figure 8(c) is a partial cross-sectional view taken
along line P-P of Figure 7(a);
Figure 8(d) is a cross-sectional view taken along line
Q-Q of Figure 7(~); and
Figure 8(e) is a cross-sectional view taken along line
R-R of Figure 7(b).
DESCRIPTION OF SYMBOLS
The first, second and third brush surfaces are
designated by numerals t, 2 and 3, respectively. Numeral
5 designates the bristle tufts of bristle row 32 which
is nearest to the brush neck 12. Numeral 6 designates
the first bristle peak. Numeral 7 designates the second
bristle peak. Numeral 22 designates the bristle valley.
Letter A designates the length of first brush surface l,
B designates the length of second brush surface 2, C
designates the length of third brush surface 3, D
designates the length of the entire bristle section. It
will be understood that lengths A, B, C and D are
measured in a direction parallel to the longitudinal
axis of the brush head of the toothbrush. E designates
the bristle height at the first peak 6; F designates
the bristle height at bristle valley 22; G designates
the brush head length; H designates the brush head
width; I designates the maximum width of the handle; J
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- 18 -
designates the width of the neck portion; K designates
the thickness of the neck portion; L designates the
entire length of the toothbrush blank as shown in Figure
6(b).
