Note: Descriptions are shown in the official language in which they were submitted.
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TITC E OF THE INyENTION
DENTAL FLOSS ARTICLE
F1EL0 OF THE iNYENTION
The present invention relates to a dental floss article for promoting oral
hygiene.
BACKGROUNC? OF THE INVEN_TiON
It is well understood that the use of dental floss is an important part of a
io total oral hygiene p~ograrn: Flossing teeth helps to prevent periodontal
disease, such as gingivitis .for example. The use of floss helps to dislodge
food
particles and plaque from interstitial surfaces of teeth. Caries will develop
on
tooth surfaces where. there is an accumulation of plaque. Although the.use of
a
toothbrush reduces plaque on the occlusal areas of teeth, a tooth brush offers
only ~ minima! reduction in plaque within the interstitial regions of the
teeth.
Dental floss is the only effective means to disrupt the accumulation of plaque
in
such interstitial. regions, thereby reducing the likelihood for the cane
development.
Unfortunately, persons requiring fixed orthodontic appliances,
2o commonly referred to in the United States as braces, and persons wearing
dental bridges, such as a Maryland style bridge for example, can not benefit
from the cleaning capabilities-associated with normal dental flossing
techniques
without the aid of cumbersome apparatus. More particularly, standard flossing
techniques are not appropriate for users of these appliances and devices
because they prevent the dental floss from freely entering into the
interstitial
regions when performing the normal up and down motion of flossing.
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In the past, a floss threader or needle has been employed to thread
dental floss between a gum line and an orthadantic appliance or Maryland
bridge. One such floss threader is disclosed in United State Patent 4,011,658.
A shortcoming of such a floss threader is that it is often very cumbersome to
use, especially for a person Lacking average dexterity. A user of such a floss
threader must thread the device prior to.appiication in the mouth for the
purposes of flossing, much like a sewing needle. ,
Another shortcoming associated with the use of a floss threader is the
potential for the device to be swallowed during use if the threader becomes
1 o separated from the floss. Children may lack the motor skiffs to remove the
separated pieces from their mouth, which, of course, is hazardous.
Attempts have been made to bond a rigid floss leader to a flexible
section of dental floss. Such an article is disclosed in United States Patent
4,832,,063. However, the bond between the two units often fails in use.
Additionally, an enlarged cross-sectional diameter at the transition point
between the ieaderand the floss may cause pain when passing the article
through the space between the teeth and gums.
As disclosed in United States Patent 39744,499; a plastic coating may
be applied to a dental floss to render a portion of the dental floss rigid.
~ Although this rriethod may be satisfactorily employed with dental floss
materials
consisting of thermoplastics, such as nylon or polyethylene, and natural
fibers
such as cotton, such a method is not useful with dental floss comprised at
least
in part of polytetrafluoroethylene (PTFE). When such.a method is practiced on
non-modified monofilaments of polytetrafluoroethylene, expanded
polytetrafluoroethylene, or full density expanded polytetrafluoroethylene, the
molten thermoplastic beads on the surface of the dental floss material and
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does not provide a rigid continuous network of the thermoplastic. The beading
of the thermoplastic is due to the inherent low surface energy and high
hydrophobicity of the polytetrafluoroethylene.
The use of polytetrafluoroethylene as a dental floss is taught in such
s United States Patents as 5,033,488~and 5,220,932. It is well accepted that
dental flosses made of polytetrafluoroethylene and forms of expanded porous
polytetrafluoroethylene are superior to nylon. and natural fiber materials.
Flosses consisting of PTFE benefit from the. law coefficient of friction
inherent
to PTFE thereby allowing the floss material. to easily maneuver between tight
to oral contacts without excessive force or severe abrading of gum tissue.
Notwithstanding the laudable benefits associated viith dental flosses
comprised
~at least. in part of PTFE; to date, secondary floss threader devices are
needed
by persons having orthodontic appliances or dental bridges, and who wish to .
use such PTFE dental floss. .
t 5 The foregoing illustrates limitations known to exist in present dente!
floss materials: Thus; it is apparent that it would be advantageous to provide
an improved dental floss article directed to overcoming one or more of the
limitations set forth above. Accordingly, a suitable alternative is provided
including features more fully disclosed hereinafter.
The present invention advances the art of dente! floss articles, and the
techniques for creating such dental floss articles, beyond which is known to
date.
In one embodiment of the present invention, a dental floss article is provided
comprising a hydrophobic fiber having a predetermined length. The
hydrophobic fiber is defined by at feast one substantially rigid portion and
at
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least one flexible portion. The at least one substantially rigid portion is
defined
by a rigidifying member that is made integral with the hydrophobic fiber such
that the hydrophobic fiber completely encapsulates the rigidifying member.
The hydrophobic fiber rnay be expanded porous polytetrafluoroethyiene
(ePTFE) or ultra high molecular weight polyethylene, for example.
In another embodiment of the present invention, a dental floss article is
provided comprising a hydrophobic fiber having a predetermined length. The
hydrophobic fiber is defined by at least one substantially rigid portion and
at
least one flexible portion. The at least one substantially rigid portion is
defined
to by a polymeric coating or covering that,is made integral with the
hydrophobic
fiber such that a length of the hydrophobic fiber is completely encapsulated
by
said polymeric coating or covering. The hydfophobic fiber may be a
monofilament or a towed fiber of expanded porous polytetrafiuoroethylene
(ePTFE) or ultra high molecular weight polyethylene, for example. The
polymeric covering may be a. tube or a taps wrapping.
In another embodiment of the present invention, a method is provided
for_producing a dental floss article comprising the steps of: providing a
porous
polymeric fiber having a predetermined length; filling a monomer within the
fiber at a predetermined location along the length of said fiber; and ,
2o polymerizing the monomer~in place within said porous polymeric fiber,
thereby
rendering said ~filfed location substantiaNy more rigid than an unfilled
region.
In yet another embodiment of the present invention a dental floss article
is provided- comprising ~a towed fiber of a fluoropolym~r or polyolefin
material.
The towed fiber may be expanded porous polytetrafluoroethylene or ultra High
molecular weight polyethylene, for example.
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The teachings of the present invention may also be employed to
produce an improved suture.
RI F DESCRIPTION Q~ THE~DRAWINGS
The foregoing summary, as well as the following detaiied'description of
a preferred embodiment of the invention, will be letter understood when read
in conjunction with the appended drawings. For purposes of illustrating the
invention, there is shown in the drawings an embodiment which is presently
preferred, it should be understood, however, that the invention is not
limited.to
1o the precise arrangement and instrumentality shown. In the drawings:
Figure 1 is an isometric view of a dental floss article of the present
invention having a semi-rigid section formed by wrapping and bonding a fber
around a stiffening material;
Figure 2 is an isometric view of a dental floss article of the present
i5 invention having a semi-rigid section formed by wrapping heat shrinkable
tubing around a fiber;
Figure 3 is an isometric view of a dental floss article of the present
invention having a semi-rigid section formed by wrapping heat shrinkable tape
around a fiber;
Zo - Figure 4 is a planer view of a dental floss article comprising a 1200
denier towed fiber in accordance with one embodiment pf the present
invention;
Figure 5 is an isometric view of a dental floss article of the present
invention having a semi-rigid section formed by coating and curing a polymeric
25 material onto towed portions of the dental floss article of Figure 4;
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Figure 6 is an isometric view of a test apparatus used to determine a
resistance to buckling loads of various semi-rigid materials;
Figure 7 is a side view of a lever arm of the test apparatus of Figure 6;
Figure 8 is an isometric view of a dental bridge; and .
Figure 9 is a view of a fxed orthodontic~appliance (braces).
, ' DETAI ,~I~DESCRIPTION OP THE lNll~~d~IQN
Referring now to the drawings, one embodiment of the dental floss
article of the present invention is generally illustrated at,10 in Figures 1,
2, 3,
to and 5. Such a dental floss article comprises an expanded porous
polytetrafluoroethylene (ePTFE) fiber 11 that defines at least one semi-rigid
portion 12 and at least one flexible portion 14. The dental floss article 10
may. .
be rolled, or otherwise disposed on a bobbin-like apparatus, and may be
placed on a supporting core so that ii may be easily integrated within a
suitable
15 dispensing apparatus (not shown). Alternatively, the dental floss article
may be
defrned by a single use length which includes a single semi-rigid portion.12
and
a single flexible portion 14; such a floss apparatus (nay be packaged in a
single
use sterile package.
As the term is used herein, expanded porous polytetrafluoroethylene
?o (ePTFE} shall mean a membrane which may be prepared by any number of
known processes, for example, by stretching or drawing processes,~by
papermaking processes, by processes in which filler materials are
incorporated.
with the PTFE resin and which are subsequently removed to Leave a porous.
stnrcture, or by powder sintering processes. Preferably, the porous
25 polytetratluoroethylene membrane is porous expanded polytetrafluoroethylene
membrane having a microstructure of interconnected nodes and fibrils; as
7
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described in U.S: Patent Nos. 3,93,566; 4,187,390; and 4,110,392, which fully
describe the preferred material and processes for making them. The eXpanded
porous polytetrafluoroefhylene membrane may be produced in filament form,
such a form is preferred. ,
_ ~~ As best illustrated by Figure 8, a typical bridge comprises a ponttc or
false tooth lfi~, which is anchored by~natural teeth 18 and.20 by way of metal
~ .
supports 22. The semi-rigid portion 12 of the dental floss article 10
facilitates.
insertion thereof between the teeth, preferably at the germ tine, thereby
acting
14, as a leader for the flexible portion 14. As bESt illustrated by Figure 9,
the semi-
rigid portion 12 also facilitates insertion of the dental floss'acficte 1~0
between
. the interstitial regions of.teeth °in cases where the person has
fixed orthodontic . "
' ~ppiiances, such.as braces 24. ' ' ..
As the term "floss" is used herein, it is intended to encompass a thread-
~5~ . like material suitable for facilitating oral prophylaxis. Although the
present. ,
invention is described in one embodiment as a dental floss article, it is ~ ~
.
contemplated that the article of the present invention may provide an
excellent
improved suture for use in various surgical applications: Accordingly,,such an
embodiment as a suture is fully contemplated by the teachings herein.
As should b~ understood, a preferred fitrer 11 for use in the dental.floss
article 10 is a fiber'of ePTFE. However; it is canterriplated that the
teachings of
the present-invention may be employed with other fibers such as polyolefrns
(e.g: ultra high molecular weight potyethytene), ~polyamides, ~polyimides,
polyurethanes, .elastomeric materials, polymer blends, or natural fibers; for
?5 example.
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In one embodiment of the present invention illustrated in Figure 1, the
dental floss article 10 is defined by semi-rigid portions 12, comprised of an
internal stiffener, stiffening member or rigidifying member 13 that is
adhesively
bonded to and wrapped within the expanded polytetrafluoroethylene (ePTFE)
fiber l 1. Flexible portions 14~are comprised of the ePTFE fiber~l1 which may
also be wrapped or folded onto itself. By wrapping the stiffener 13'within the
ePTFE fiber 11, an unexpected improvement is achieved. The well known low
coefficient of friction far the el'TFE material improves the feel or slide of
the
stiffener through a persons teeth while providing additional strength and
to support to the stiffener to resist buckling forces due to the
frictional~force
created when passing the stiffener through ~an interproximal area. As should
be understood, such an embodiment,of the present invention completely
encapsulates a stiffening member, thereby rendering the otheriniise limp
expanded PTFE fiber 11 semi-rigid. Also, such an embodiment of the present
invention doss not create an abrupt, change in the cross-sections! area of the
dental floss article between the stiffened portion 12 and the flexible portion
14,
thereby providing comfort to a user of the dental floss article 10. Also, by
completely encapsulating the stiffening member 13, the possibility that the
stiffening member will separate from the ePTFE fiber is reduced. The
encapsulation of the stiffening member also provides additional tensile
strength
and stiffness to the semi-rigid portion 12.
Great tailorabiiity is afforded to the dental floss article 10 by using. a
wide variety of stiffeners such as polymers, metals, etc., and any suitable
adhesive for bonding the stiffeners with the ePTEE fiber 11. The ePTFE fiber
?s can be a monofilament, laminate, twist, braid or filled product to offer
further
tailorability to the stiffened section, as well as to the properties of the
dental
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floss. Coloring may be added to the dental floss article 10 to help identify
either the semi-rigid portion 12 of the floss, or the the flexible portion 14,
or
both. A preferred stiffener is a single, flexible, nylon filament
approximately 12
to 125 mm in length, and most preferably approximately 50 to 80 mm in length.
The stiffener may have any suitable dimensional characteristics including, but
not limited to, round, square, rectangular or triangular cross sections, for
example. . However, a round cross section .is preferred. The stiffener may be
of
various suitable diameters, preferably from 0.35 to 0.55 mm. The adhesive
can be any suitable form such as a transfer adhesive; cyano acrylate, epoxy,
to hot melt adhesive, UV cure adhesive, or silicone, and most preferably a hot
melt or UV cure adhesive system.
The stiffness of the semi-rigid portion 12 of the dental floss article 10 is
a critical factor in that if a leader, or threader end of the article is too
stiff, it
becomes very difficuif and painful to maneuver the semi=rigid portion 12
throuGh the back region of an occ~usal sits. However, some degree of
flexibility
is required in the semi-rigid portion l2 so that a.user can easily divert a
tip of
the semi-rigid portion towards the front of his or her mouth, using the
tongue,
thereby permitting the user to capture the semi-rigid portion with the fingers
and pull the trailing flexible portion 14 into a desired location for the
flossing
2o activity.
1n another embodiment of the present invention illustrated in Figure 2,
the semi-rigid portion 12 may be formed by the' use of heat shrinkable tubing
15. For example, various polymer tubing is available, which upon heating to wn
aiapropriate temperature, will relax and shrink upon itself and any object
placed
internal to the tube. Any number of heat shrinkable tubings are suitable, such
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as but not limited to, poiytetrafluoroethylene, fluorinated ethylene propylene
(FEP), low density polyethylene, pofyvinyichloride, or polyester. ,
As illustrated in Figure 3, in another embodiment of the present
invention, the stiffening of a section of fiber 11 may also be accomplished by
tape wrapping a sheet,or filrti 15A of shrink type material onto the fiber 11,
followed by heating to allow consolidation of the sheet or film. This may be
accomplished by-using a helical tape wrap pattern, or a straight lap tape wrap
similar to the tape wrap of a commercially available shoe string end. A wrap
'angle ~ may be from 4 to 85 degrees, with a preferred range of 0 to 45
degrees. The wrap material may consist of a variety of polymeric and metaNic
tape or ribbon materials, but a preferable material is PTFE and~expanded
PTFE for its low coefficient of friction properties. if a more aggressive bond
is
required, the tape wrap may be FEP.
fn another embodiment of the present invention, the semi-rigid portion
of the dental floss a~ticie 10 can be achieved by the incorporation of a
center
core of polymeric or metallic material within the cross-section of an ePTFE'
fiber. This incorporation can be easily accomplished during the production of
the ePTFE fiber and is similar to insertion molding. The incorporated filament
material is interrnitiently introduced at or near a converging extrusion die
prior
to the area where a PTFE extrudate exits the extrusion die. The extruded
PTFE material forms around the incorporated material. The incorporated ,
.material provides for regions where the article is substantially stiffer than
other
areas of the article. Heat and pressure may be used to render the incorporated
areas even stiffer as compared. to the article stiffness prior to the heat and
~?5 pressure operation, An enhancement to this embodiment is realized if the
incorporated filament material is made of a polymeric material, such that the
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material is not intermittently introduced as described above but rather, is
continuously incorporated within the cross-section. of the PTFE extrudate. As
it
is well known in the art of the production of expanded porous PTFE, the matrix
terisiie strength of extruded PTFE material is substantially increased as the
material is expanded, as described in United States Patent 3,953,566. The
substantial increase of the matrix tensile strength of the expanded porous
PTFE, over the non-expanded PTFE, is greatly desired in that the overall
tensile strength of a floss article or device should be sufficient so that in
normal
use of the floss articte, the article ~r device does not break in the users
teeth
due to the lack of tensile strength of the floss article or device. In
converting
the PTFE extrudate into a form of expanded porous .PTFE, and especially a
coextrusion of PTFE where the PTFE is coextruded with a polymeric material
(e.g. nylon) within the cross-section of the PTFE matrix, an unexpected result
is realized if sections of the continuous coextrusion are prevented from
15 undergoing a transformation, from non-expanded PTFE to expanded porous
PTFE, and other sections of the coextrusion are converted into forms of
expanded porous PTFE. The non-expanded regions of the coextrusion are
substantially more rigid than the expanded regions in that, the polymeric
material incorporated within the PTFE matrix becomes extremely thin as the
?o . expanded sections are stretched. The stiffing effect of the incorporated
polymeric fttament material is thus substantially minimized as the polymeric
material cross-sectional area becomes small and therefore, looses its
geometrical presence within the ePTFE matrix. As -it is well known, if PTFE
undergoes an uniaxial expansion operation using certain known conditions of
?5 temperature and expansion rate, the density of the. PTFE decreases as the
linear length increases, yielding an extremely strong filament which is not
CA 02450178 2003-12-18
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susceptible to shredding. The presence of the incorporated polymer filament is
only realized in th.e semi-rigid portions where the extrudate did not undergo
an
expansion operation. Regions of the extrudate can easily not undergo the
expansion process by expanding the coextrusion material between two nip
rollers. For regions where the less stiff portions are desired, the second of
the
two nip rollers rotate at a faster surface velocity than the first, thereby
creating
tension on the extrudate restrained between the two nips. For regions where
the portion is desired to be more stiff than the expanded sections, the second
nip roller assembly has the same surface velocity as the. first nip roller
to assembly thus creating no tension in the extrudate, hence no stretching
occurs:
The semi-rigid sections can be further enhanced by application of heat and
pressure over the stiff sections thereby thermally and mechanically -
manipulating the incorporated polymeric material thus providing for a better
a
bond and either maintaining or conforming the semi-rigid section to a
desirable
15 geometric configuration. Such geometric configurations for the semi-rigid
section include, but are not limited to, a semi-curve-Linear form, straight
sword
type form, or a compound angular form. tt is preferred that the semi-rigid
section contain at least some curvature similar to an upholstery needle since
the curvature permits the user to easily grasp the semi-rigid section after
the ,
20 ~ user places the device through his teeth.
In another embodiment of the present invention, a semi-rigid portion 12
may be achieved by the incorporation of a rnonomer within the matrix of the .
.
expanded porous PTFE, and then subsequently polymerizing the monomer in
place within the ePTFE matrix, thereby rendering the filled region
substantialty
25 more stiff than the unfilled regions. The monomer when polymerized or cured
consists of a material whose modulus of elasticity is higher than that of
CA 02450178 2003-12-18
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expanded PTFE, such that when used in a composite construction of the two
materials, the polymerized incorporated material provides far a significant
increase of the overall modulus of elasticity of the composite structure. The
increase of the modulus of elasticity is realized by the user as an increase
in
stiffness of the fiber 11
The incorporated monomer material can be~dissoived into a solvent.
The viscosity of the solvent and monomer mixture should be very low so that it
can easily be placed into the porous matrix of the expanded PTFE. It is
preferred that the solvent has an .overall oil rating number of two or less,
such
to that it cart easily be placed into the ePTFE matrix. For materials with
higher oil
rating numbers, difficulty is shown when placing these materials into the
ePTFE
matrix due to the extremely low surface energy of the ePTFE. Surface
modifications, such as corona treating or plasma treating, can be applied to
the
ePTFE to increase the hydrophilic nature of the material, thus making the
~ ePTFE more receptive for solvent filling.
Other methods for incorporating the monomer into the ePTFE matrix
may include vacuum disposition or coextrusion. The incorporated monomer
can be polymerized by several mechanisms which are particular to the
monomer used. Polymerization initiation can be UV, thermal, pressure (i.e.
shear gradient), or chemically activated. Typical activated materials include
thermosets'and epoxy polymers, where thermosets are cured using a
temperature gradient and epoxies are cured by chemical interaction.
The high temperature stability of the base PTFE structure provides for
an excellent carrier for the incorporation of a thermoset during blending of
raw
PTFE powder prior to extrusion. After the i;oextrusion extrudate has been
converted into a form of expanded PTFE, the thermoset can be cured or
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polymerized at desired locations, thus providing for semi-rigid and non-rigid
sections of the dental floss article. This method of blending the curable or
the
polymerizable monomer with the raw PTFE powder negates the potential
shortcoming associated with the inherent high hydfophobicity of PTFE. As
mentioned previously, the high hydrophobicity prevents viscous solvents,
especially viscous solvents with high surface energies, froi~n being easily
placed
or absorbed into the porous expanded PTFE matrix.
In yet another embodiment of the present invention, extremely fine .
particles of a thermoplastic polymer can ~be introduced into the fibril-node
to structure of the ePTFE, followed by a curing operation'to melt and reflovv
the
polymers to make a continuous network within the matrix of the ePTFE thereby
stiffening the fiber in desired locations.
As illustrated in Figure 5, another embodiment of the present invention,.
the semi-rigid portion 12 can be formed by application of a polymer coating or
t5 dispersion to the fiber 11 in selected predetermined locations, foll~v~ed
by
curing of the polymer to a semi-rigid state. For example, suitable polymer
dispersions may include, but are not limited to, polytetrafluoroethylene
(PTFE),
fluorinated ethylene-propylene (FEP), and polyvinylidene fluoride (PVDF).
Though application of these polymers to the fiber atone will create some
20 degree of adherence, it is important to modify the surface of the fiber to
promote a much more tenacious, bond. This surface preparation can be
accomplished by a variety.of techniques including, but not limited to,
mechanical, chemical, or electrochemical means, such as roughening the
surface with sandpaper, treatment with an etchant, or by corona surface
25 modification treatment. A preferred technique is to use a fully towed
fiber, or to
intermittently "tow° a 12 to 125 mm, preferably 50 to 80 mm, section of
an
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ePTFE fiber, approximately every 0.5 meters along the length. The towing
operation consists of running the fiber 11 over a rotating pinwheel to create
a
"tow yarn". As shown in Figure 4, a tow yarn 20 is a lattice structure of long
randomly interconnected filaments 22 of ePTFE making up a continuous fiber
24. As shown in Figure 5, the tflw yarn 20 is then coated with a polymer in
predetermined~locations, followed by curing for an appropriate time and at an
appropriate temperature, for the particular polymer used, to form a semi-rigid
section 12. In doing so, the polymer has much greater surface area to bond
with during polymerization, and at the same time mechanically locks the tow
to filaments together with a continuous network of polymer to form one
continuous semi-rigid desired section. The shape arid texture of the semi-
rigid
portion 12 can be manipulated by processing the polymer containing end
through a molding die while still in the semi-viscous state. In doing so, one
can
achieve different end characteristics suitable and desired for guiding ttie
floss
thr ough the interstices between the teeth and gums of the user. The color
too.
can be manipulated by placing desired pigments into the polymer prior to the
coating or dipping process thus helping the user to identify the semi-rigid
sections to be used as the treading device of this article. .
To enhance gripping of the dental floss article of the present invention,
2o the article may be in part or in total, coated with a layer of wax.' The
wax may
be any suitable wax such as carnuba, natural beeswax, candeliHa, petroleum
wax, synthetic petroleum wax, oxidized polyethylene, or micro crystalline. It
has been found that a wax coating of from 0.5% to about 20% by weight is
achievable, but a coating of 2 to 10% is preferable.
The.dental floss article of the present invention may be waxed using
standard lick roller type waxing machines. The article may also be waxed
,a ,
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using a number of liquid wax spray techniques such as those used for
application of waxes on citrus fruit or other produce. The article may also be
dip coated in a molten bath of wax. In addition to enhanced grippability of
the
dental floss article, the wax may be used to cover, or to carry an assortment
of
materials on the dental floss 'article to be delivered to the mouth and teeth.
These materials may include, but are not limited to, flavoring oils,
whiteners,
abrasives, anti-bacteriais; anti-tarter agents, or medicaments, such as,
tetracycline, iodine, vitamins, etc.
As best seen by reference to Figure 6, a testing apparatus 40 was
io developed and built to determine the stiffness of the. semi-rigid portion
12. The
testing apparatus comprises an artificial dental contact site made from two
parallel adjacent 6.35 mm glass stirring rods 42, approximately 5~0 mm long.
The bottom glass rod is stationary-and fixed to a base 44 while the top glass
rod is mounted to a lever arm 47 that is counterbalanced by member 46 and
t5 free to pivot about its bearing 43: The bearing is fixed to an anvil
5lJ.which is
stationary and fixed to the base 44. A load can be applied to the glass
contacts by placing various weights into a load tray 52. A stiffened fiber or
threading device 12 is presented perpendicular to the glass contacts and
guided, so that a tip of the semi-rigid portion meets a tangent line between
the
2o two glass rods. The fiber is mounted to a tray assembly 54 which travels
along
two guide rails 56 and is fixed to the tray by clamp 58, 25 mrn behind tile
tip,
exposing 25 mm of the semi-rigid portion. The tray assembly is then hand
cranked moving the fiber horizontally into the glass contact point 42. The
semi-
rigid portion will either lift the contacts and penetrate through, or buckle
from
25 the applied load. '
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Referring to Figure 7; the load tray 52 is mounted with its center 50 cnm
away from the pivot point of the bearing 48, distance "a". The glass rod
contact
point is 150 mrn away from the bearing, distance "b": For the purpose of
calculating the applied load at the glass contact points, which will cause a
frber ,
to buckle rather than force the two glass rods apart, the mass applied to the
Ivad tray 52 is assumed to be centrally located in the tray above the center
line
of the lever arm 47. This allows for the calculation that, FCC = FA(a)~b. The
load to resist.buokling Foc of different fibers can be quantified in this
fashion. A
range of 3 to 1200 grams has been determined to be suitable for the semi-rigid
to portion, as measured by the testing apparatus, with a preferred range of 10
to
60 grams.
Without intending to limit the scope of the present invention, the"
apparatus and method of production of the present invention may be better:
understood by referring to the following examples:
Example 11
2200 denier flat ePTFE fiber (obtained from W. L. Gore and Associates,
Inc.; Elkton, MD, Part No. GY012T1-Tape) was cut into 600 mm sections.
Manofilament nylon of 0.016" diameter having a circular cross section was cut
Zo into pieces 50 to 80 mm long. A medical grade trarisfer adhesive ARCARE
7396 supplied by Adhesive Research, Inc., Glen Rock, PA was used to bond
the two discrete materials together. A ~50 to 80 mm section of transfer
adhesive having a width greater than the width of the fiber was applied to the
ePTFE fiber. The transfer adhesive was then cut down and sized to the width
2s of the fiber. The backing tape of the transfer adhesive was then removed
exposing a section 50wto 80 mm long of adhesive on the ePTFE. A piece of the
E CA 02450178 2003-12-18
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nylon monofilament having a 0.016 inch diameter was placed centrally along
the length of the adhesive coated ePTFE fiber, then the flat ePTFE fiber was
closed around the monofilament in a cigarette wrapped fashion.wrapping the
exterrval surfaces of the nylon and totally. encasing it. This resulted in an
article
having one semi-rigid sectiari of between 50 and 80 mm in length with the
remainder of the article being, flexible and essentially limp. A buckling load
resistance of 30 grams was tested on the buckling load resistance test
apparatus of Figures 6 and, 7.
to Example 22
The procedure of Example 1 was used lo produce additional dental
floss articles, with the exception that the nylon monofilaments of varied
cross
sectional diameters of 0.070", ~.012", 0.015", 0.017", and 0.021" were
employed. The resistance to buckling load of the semi-rigid section of each of
t5 these articles increased as the cross-section of the stiffening member
increased.
The procedure of Example 1 was used to produce a dental floss article
~o except that the nylon monofiiament had a triangular cross-section.
c 'n 4_
Heat shrinkable poiyte#rafluaroethylene tubing from Zeus Industrial
Products, Inc., Raritan, NJ, identified as TFE Teflon SUB-LITE-WALLT"" AWG
?5 Size No. 34 having an inside expanded diameter of 0.020", was cut into 50
to
80 mm sections. A 1150 denier flat ePTFE fiber (obtained from W. L. Gore and
CA 02450178 2003-12-18
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Associates, Inc., Elkton, MD, Part No. GY012T1) was cut into a 600 mm
section. One end of the ePTFE fiber was threaded through the heat shrink
tubing leaving the tubing located at a position approximately two thirds down
the length of the fiber. Both ends of the fiber were tied to a two peg
aluminum .
stand supporting the fiber under slight tension so that it did. not rest on
the base
of the stand. The metal stand was then placed into an oven at 350 degrees
centigrade for 5 minutes to allow the tubing to shrink, per the instructions
from
the manufacturer. The stand containing the fiber was removed from the oven
and allowed to caol to room temperature. The heat shrink tubing collapsed on
to itself and squee2ed dawn on the ePTFE fibEr and.wa.s mechanically held in
place creating a semi-rigid section. The fiber, was then cut through the heat
shrink tube location to make a dental floss article having a semi-rigid
portion
and a flexible portion.
s
is Example 5
Heat shrinkable low density polyethylene tubing from Raychem Corp.,
Menlo Park, GA, identified as MT2000-1mm having an inside expanded
diameter of 0.045", was cut into 50 to 80 mm sections. A 1150 denier flat
ePTFE fiber (obtained from W. L. Gore and Associates, Inc., Eikton, MD, Part
?o No. GY012T1 ) was cut into a 600 mm section. One end of the ePTFE fiber
was threaded thFOUgh the heat shrink tubing leaving the tubing located at a
position approximately two thirds down the length of the fiber. Both ends of
the
fiber were tied to a two peg aluminum stand supporting the fiber under slight
tension so that it did not rest on the base of the stand. The metal stand was
25 then placed into an oven at 125 degrees centigrade for 1 minute to allow
the
tubing to shrink, per the instructions from the manufacturer. The stand .
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containing the fiber was removed from the overi and allowed to cool to room
temperature. The heat shrink tubing collapsed on itself and squeezed down on
the ePTFE fiber, and was mechanically held in place creating a semi-rigid
section. The fiber was then cut through the heat shrink tube location to make
a
dental floss article having a semi-rigid portion and' a flexible portion.
x m I ,~
A 1200 denier towed ePTFE fiber (obtained from W. L. Gore and
Associates, Inc:, Elkton, MD, Part No. WY012T1-Tow) was cut into a 600 mm
to section. The tow fiber was tied at both ends to a two peg aluminum stand
supporting the fiber under slight tension so that it did not rest on the base
of the
stand. A section of fiber between 50 to 80 mm long was coated with a
polyvinylidene fluoride (PVDF) dispersion obtained from Whitford Corporation,
West Chester, PA under the trade name DYKOR~ 202 Clear Topcoat. The
5 coating was applied pith a small paint b!vsh or cotton swab. The coated
fiber
and a 2-peg stand were then placed into an air oven at 265 degrees centigrade
for a period of 5 minutes to cure the polymer. The stand and fiber were
removed from the oven and allowed to cool to room temperature. The cured
polymer physically and mechanically locked the towed fiber together in the
Zo specified section and created a semi-rigid sectlan ~f fiber having an oval
shape
with major outer diameter of 0.027" and minor,outer diameter of 0.021 ". The
fiber was then removed from the. stand and cut to length. The remaining
uncoated section of the fiber was then waxed.
?5 Exam lip a 7
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The procedure of Example 6 was used to' create a dental floss article,
with the exception that slightly more polymer dispersion was coated onto the
towed fiber prior to curing, resulting in a semi-rigid section having~a. major
outer
diameter of 0.025" and a minor outer diameter of 0.023".
.F_",~c. a m Ip a 8_
The procedure of Example 6 was used to create a dental floss article,
with the exception that slightly more polymer dispersion was coated onto the
towed fiber prior to curing resulting in a semi-rigid section having a major
outer.
to diameter of 0.030" and a minor outer diametef of 0.024".
Exams Ip a 9
1150 and 2200 denier ePTFE fibers of various lengths (obtained from
W. L. Gore and Associates, Inc., Elkton., MD, Part Na. GY012T1 and
is GY012T1-Tape, respectively) were intermittently towed in discrete locations
of
approximately 50 to $0 mm along the length of the fiber. The towed sections
were located approximately 1 meter apart from each other. The fibers were
then cut into a 600 mm sections, with each section containing one towed
location of 50 to 80 mm in length. These fibers were. tied at both ends to a
two
ao peg aluminum star<d supporting the fibers under slight tension so that they
did
not rest on the base of the stand.- The towed sections of the fibers were
coated
with a polyvinylidene fluoride (PVDF) dispersion obtained from Whitford .
Corporation, West Chester, PA under the trade name DYKOR~ 202 Clear
Topcoat. The coating was applied with a small paint brush or cotton swab:
?5 The coated fibers on the 2-peg stand were then placed into an air oven at
265
degrees centigrade for a, period of 5 minutes to cure the polymer. The stand
° ' CA 02450178 2003-12-18
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and fibers were removed from the oven and allowed to cool to room
temperature. The cured polymer physically and mechanically locked the towed
fiber section together thereby creating a semi-rigid portion. The fibers were
then removed from the stand and cut to length. The remaining uncoated
section of the fiber was then 'waxed:
Table 1 shows the resistance to buckling loads of various articles as
determined by the teachings herein. A preferred range for resistance to
buckling for the article of the present invention was determined to be from
about 10 to about 80 grams.
CA 02450178 2003-12-18
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TABLE 1
TESTED ARTICLE LOAD AT
CONTACTS ~(FG~j
IN GRAMS
O.n10" Aluminum wire ' 117
0.015" Copper wire ~ 250
0.026" Copper wire 1167
0.016" diameter nylon monofi(ament i 6
'
Example 1: ePTFE wrapped 0.016" dia. 30
nylon
monofilament ~ . ~ -
Example 4: TFE SUB-L-ITE-WALLT"" shrink 18
wrapped
fiber '
Example 5: MT2000 LDPE shrink wrapped 83
ePTFE
. fiber
Example 6: DYKOR~ 202 Clear Topcoat '.021"18
x
.027" dia. ~ .
Example 7: DYKOR~ 202 Clear Topcoat .023"32
x
.025" dia. ~ '
Example 8: DYKOR~ 202 Clear Topcoat .024"42
x
.030" dia..
