Note: Descriptions are shown in the official language in which they were submitted.
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DENTIFRICE COMPOSITION COMPRISING BINDER SYSTEM COMPRISING
HYDROPHILIC CLAY MATERIAL
FIELD OF THE INVENTION
The present invention relates to a dentifrice composition comprising a binder
system
comprising hydrophilic clay material, which provides high thermal stability
over a wide range of
formulations.
BACKGROUND
Dentifrice compositions such as toothpastes are routinely used by consumers as
part of
their oral care hygiene regimens. It is well known that oral care products can
provide both
therapeutic and cosmetic hygiene benefits to consumers. Therapeutic benefits
include, but are
not limited to, caries prevention, gingivitis prevention, and hypersensitivity
control. Cosmetic
benefits include, but are not limited to, control of plaque and calculus
formulation, removal and
prevention of tooth stain, tooth whitening, breath freshening, and mouth feel
aesthetics such as
fresh sensation or slippery sensory feel.
Usage of abrasive material such as silica has long been considered critical
for delivering
the above mentioned therapeutic and cosmetic benefits of a dentifrice
composition. Abrasive
materials provide physical abrasion between toothbrush and teeth to clean
plaque, stain, and
calculus, while also build rheology and structure of the dentifrice for
maintaining thermal
stability of the overall formulation.
At the same time, however, usage of abrasive materials at a high level may
have negative
effects to overall formulation. For example, the cost of silica itself is
expensive. Further,
silica adsorbs components in a typical dentifrice composition such as active
agents, flavors, and
foaming agents, thereby the concentrations of these components must be
adjusted according to
the foreseen loss by silica. Still further, certain active agents such as
cetylpyridinium chloride
have poor compatibility with silica, and therefore cannot be included in a
dentifrice
composition, despite its known effectiveness. In another aspect, it is a
conception of the
general consumer that abrasive materials may erode the enamel, if the teeth
are brushed too
intensively.
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Based on the foregoing, there is a need for a dentifrice composition which is
low in, or
free of abrasives, which can still deliver the benefits of a regular
dentifrice composition.
Specifically, there is a need for a dentifrice composition which is thermally
stable over a wide
range of formulations, and which can deliver the same cleaning benefits on the
market.
SUMMARY
The present invention is directed to a dentifrice composition comprising:
(a) a binder system which provides a viscosity of from about 10,000 Pas to
about 450,000
Pas comprising:
i) a hydrophilic clay material;
ii) a modified cellulose polymer
iii) a carboxyvinyl polymer; and
iv) a natural gum derived anionic polymer;
(b) an effective amount of an oral care active; and
(c) a polar solvent carrier.
The present invention is further directed to a method of cleaning the teeth
absent an
abrasive.
These and other features, aspects, and advantages of the present invention
will become
evident to those skilled in the art from a reading of the present disclosure
with the appended
claims.
DETAILED DESCRIPTION
The following is a list of definitions for terms used herein.
"Comprising" means that other steps and other ingredients which do not affect
the end
result can be added. This term encompasses the terms "consisting of" and
"consisting
essentially of".
All percentages are by weight of total composition unless specifically stated
otherwise.
All cited references are incorporated herein by reference in their entireties.
Citation of
any reference is not an admission regarding any determination as to its
availability as prior art to
the claimed invention.
All ratios are weight ratios unless specifically stated otherwise.
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The present invention, in its product and process aspects, is described in
detail as
follows.
a) Binder System
The composition of the present invention comprises a binder system which
swells or
thickens with the presence of a polar solvent, and provides a safe and
aesthetically pleasing base
for oral care use. The present binder system comprises a hydrophilic clay
material, a modified
cellulose polymer, a carboxyvinyl polymer, and a natural gum derived anionic
polymer, each of
which are detailed below. The combination of the specific 4 binder materials
provides a
suitable rheology for the present dentifrice composition at relatively low
amounts of each binder,
and hence low cost, while also being capable of encompassing various oral care
actives. It has
surprisingly been found that the present binder system provides a stable
dentifrice composition
when abrasive materials are used at low levels, such as less than about 10% by
weight of the
composition, and even when substantially no abrasive material is used. The
present binder
system provides a suitable viscosity for a typical toothpaste form, of from
about 10,000 Pas to
about 450,000 Pas, preferably from about 10,000 Pas to about 250,000 Pas as
measured by
Brookfield viscometer with T-E spindle.
The amount of each of the 4 binders is selected based on the desired rheology
and
aesthetic profiles. The total binder system is preferably from about 0.1% to
about 10%, more
preferably from about 0,1% to about 5%, still preferably from about 0.1% to
about 3%, of the
entire composition.
a-i) Hydrophilic Clay Material
The composition of the present invention comprises a hydrophilic clay
material. The
hydrophilic clay material is preferably comprised, by weight of the entire
composition, at from
about 0.01% to about 5%, more preferably from about 0.01% to about 4%.
Hydrophilic clay materials useful herein include natural and synthesized
layered silicate
minerals, fumed silicas, thickening precipitated silica, and mixtures thereof.
Layered silicate
minerals may be naturally occurred, or synthesized to have magnesium
substituted with certain
portions of the mineral. The fumed silicas are those that provide very little
to no abrasive
function having a particle size of smaller than about 5 m, typically from
about 1 nm to about 1
m. The thickening precipitated silica are those having a DOA value of at least
about 150
mf/100g, preferably at least about 250 mf/100g, and having a particle size of
about 1 m to
about 50 m. The thickening precipitated silica can be distinguished from
abrasive silica
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material, due to its high oil absorbing capability, as defined by the DOA
value. Such capability
provides thickening property.
Commercially available hydrophilic clay materials useful herein include
synthesized
layered magnesium silicate by the tradename LAPONITE series available from
Rockwood
Additives Limited and Southern Clay Company, fumed silica having an average
particle size of
about 12 nm by the tradename AEROSOL series and CAB-O-SIL available from Cabot
&
Degussa Corporation, amorphous precipitated silica by the tradename ZEODENT
165 from J.
M. Huber Company and SYLOX 15 from Grace Davision, and precipitated silica by
the
tradename TIXOSIL from Rhodia.
a-ii) Modified Cellulose Polymer
The composition of the present invention comprises a modified cellulose
polymer. The
modified cellulose polymer is preferably comprised, preferably comprised, by
weight of the
entire composition, at from about 0.01% to about 5%, more preferably from
about 0.01% to
about 4.5%.
Modified cellulose polymers are useful binder materials herein for building
continuous
structure to the composition. Modified cellulose polymers useful herein
include sodium
carboxymethyl cellulose, polyvinylpyrrolidone, hydroxyethylpropylcellulose,
hydroxybutyl
methyl cellulose, hydroxypropy methyl cellulose, and hydroxyethyl cellulose.
Particularly
useful commercially available materials include sodium carboxymethyl cellulose
by the
tradename BLANOSE series, OPTICEL 100, and AQUALON series from Hercules;
hydroxyethylpropylcellulose by the tradename KLUCEL series from Hercules,
hydroxypropy
methyl cellulose by the tradename TF-E25 from YIXING CITY NO.8 CHEMICAL PLANT
and
by the tradename BENECEL series from Hercules.
a-iii) Carboxyvinyl Polymer
The composition of the present invention comprises a carboxyvinyl polymer. The
carboxyvinyl polymer is preferably comprised, preferably comprised, by weight
of the entire
composition, at from about 0.01 Io to about 5 Io, more preferably from about
0.01 Io to about 3 Io.
Carboxyvinyl polymers are useful binder materials herein for building a three
dimensional structure in combination with the hydrophilic clay materials
disclosed hereinabove.
Carboxyvinyl polymers useful herein include those by the tradename of CARBOPOL
series (or
CARBOMER) such as CARBOPOL 956, 934, 940, 941, 1342, ETD 2020, ULTREZ 10" from
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Noveon Inc., CARBOPOL 934, 940, 974 P from B. F. Goodrich and SYNTHALEN K
available
from 3V Company.
a-iv) Natural Gum Derived Anionic Polymer
The composition of the present invention comprises a natural gum derived
anionic
5 polymer. The natural gum derived anionic polymer is preferably comprised,
preferably
comprised, by weight of the entire composition, at from about 0.01% to about
5%, more
preferably from about 0.01% to about 3%.
Natural gum derived anionic polymers are useful binder materials herein for
effectively
adding viscosity. Natural gum derived anionic polymers useful herein include
carrageenan,
xanthan gum, gellan gum, and locust bean gum. Particularly useful commercially
available
materials include xanthan gum by the tradename KELDENT series available from
CP Kelco,
and by the tradename RHODICARE series from Rhodia; gellan gum by the tradename
KELCOGEL series from CP Kelco; and locust bean gum by the tradename GELLOID LB
series
from FMC BioPolymer.
a-v) Other Binders
Also useful as binder material herein are starch and carrageenan. Carrageenan
is
commercially available by tradename VISCARI series and GELCARIN series from
FMC
BioPolymer, by the tradename MEYPRO-SOL series from Meyhall AG, and by the
tradename
GENUVISCO series, GENU series and GENUTINE series from CP Kelco.
b) Oral Care Active
The composition of the present invention comprises an oral care active which
delivers
the intended therapeutic oral care benefit. Oral care actives useful herein
include anti-calculus
agents, stannous ion sources, fluoride ion sources, whitening agents, anti-
microbial agents, anti-
plaque agents, anti-inflammatory agents, nutrients, antioxidants, anti-viral
agents, analgesic and
anesthetic agents, zinc-containing layered material, and mixtures thereof.
b-1) Anticalculus Agent
Useful oral care agents herein include an anti-calculus agent, which in one
embodiment
may be present from about 0.05% to about 50%, by weight of the oral care
composition, in
another embodiment is from about 0.05% to about 25%. The anti-calculus agent
may be
selected from the group consisting of polyphosphates (including
pyrophosphates) and salts
thereof; polyamino propane sulfonic acid (AMPS) and salts thereof; polyolefin
sulfonates and
salts thereof; polyvinyl phosphates and salts thereof; polyolefin phosphates
and salts thereof;
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diphosphonates and salts thereof; phosphonoalkane carboxylic acid and salts
thereof;
polyphosphonates and salts thereof; polyvinyl phosphonates and salts thereof;
polyolefin
phosphonates and salts thereof; polypeptides; and mixtures thereof. In one
embodiment, the
salts are alkali metal salts. Polyphosphates are generally employed as their
wholly or partially
neutralized water-soluble alkali metal salts such as potassium, sodium,
ammonium salts, and
mixtures thereof. The inorganic polyphosphate salts include alkali metal (e.g.
sodium)
tripolyphosphate, tetrapolyphosphate, dialkyl metal (e.g. disodium) diacid,
trialkyl metal (e.g.
trisodium) monoacid, potassium hydrogen phosphate, sodium hydrogen phosphate,
and alkali
metal (e.g. sodium) hexametaphosphate, and mixtures thereof. Polyphosphates
larger than
tetrapolyphosphate usually occur as amorphous glassy materials. In one
embodiment the
polyphosphates are those manufactured by FMC Corporation, which are
commercially known as
Sodaphos (n=6), Hexaphos (n=13), and Glass H(n=21, sodium hexametaphosphate),
and
mixtures thereof. The pyrophosphate salts useful in the present invention
include, alkali metal
pyrophosphates, di-, tri-, and mono-potassium or sodium pyrophosphates,
dialkali metal
pyrophosphate salts, tetraalkali metal pyrophosphate salts, and mixtures
thereof. In one
embodiment the pyrophosphate salt is selected from the group consisting of
trisodium
pyrophosphate, disodium dihydrogen pyrophosphate (Na2H2P2O7), dipotassium
pyrophosphate,
tetrasodium pyrophosphate (Na4P2O7), tetrapotassium pyrophosphate (K4P207),
and mixtures
thereof. Polyolefin sulfonates include those wherein the olefin group contains
2 or more carbon
atoms, and salts thereof. Polyolefin phosphonates include those wherein the
olefin group
contains 2 or more carbon atoms. Polyvinylphosphonates include
polyvinylphosphonic acid.
Diphosphonates and salts thereof include azocycloalkane-2,2-diphosphonic acids
and salts
thereof, ions of azocycloalkane-2,2-diphosphonic acids and salts thereof,
azacyclohexane-2,2-
diphosphonic acid, azacyclopentane-2,2-diphosphonic acid, N-methyl-
azacyclopentane-2,3-
diphosphonic acid, EHDP (ethane- 1 -hydroxy- 1, 1,-diphosphonic acid), AHP
(azacycloheptane-
2,2-diphosphonic acid), ethane-1-amino-l,1-diphosphonate, dichloromethane-
diphosphonate,
etc. Phosphonoalkane carboxylic acid or their alkali metal salts include PPTA
(phosphonopropane tricarboxylic acid), PBTA (phosphonobutane-1,2,4-
tricarboxylic acid), each
as acid or alkali metal salts. Polyolefin phosphates include those wherein the
olefin group
contains 2 or more carbon atoms. Other useful material include synthetic
anionic polymers,
including polyacrylates and copolymers of maleic anhydride or acid and methyl
vinyl ether (e.g.,
Gantrez), as described, for example, in U.S. Patent 4,627,977, as well as,
e.g., polyamino
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propane sulfonic acid (AMPS), zinc citrate trihydrate, polyphosphates (e.g.,
tripolyphosphate;
hexametaphosphate), diphosphonates (e.g., EHDP; AHP), polypeptides (such as
polyaspartic and
polyglutamic acids), and mixtures thereof. Additionally, the oral care
composition can include
a polymer carrier, such as those described in U.S. Patent Nos. 6,682,722 and
6,589,512 and U.S.
Application Nos. 10/424,640 and 10/430,617.
b-2) Stannous Ion Source
Useful oral care agents herein include a stannous ion source. The stannous
ions may be
provided from stannous fluoride and/or other stannous salts. Stannous fluoride
has been found
to help in the reduction of gingivitis, plaque, sensitivity, and in improved
breath benefits. The
stannous ions provided in an oral composition will provide efficacy to a
subject using the
composition. Although efficacy could include benefits other than the reduction
in gingivitis,
efficacy is defined as a noticeable amount of reduction in in situ plaque
metabolism.
Formulations providing such efficacy typically include stannous levels
provided by stannous
fluoride and/or other stannous salts ranging from about 3,000 ppm to about
15,000 ppm stannous
ions in the total composition. Below about 3,000 ppm stannous the efficacy of
the stannous is
not sufficient. The stannous ion is present in an amount of from about 4,000
ppm to about
12,000 ppm, in one embodiment from about 5,000 ppm to about 10,000 ppm. Other
stannous
salts include organic stannous carboxylates, such as stannous acetate,
stannous gluconate,
stannous oxalate, stannous malonate, stannous citrate, stannous ethylene
glycoxide, stannous
formate, stannous sulfate, stannous lactate, stannous tartrate, and the like.
Other stannous ion
sources include, stannous halides such as stannous chlorides, stannous
bromide, stannous iodide
and stannous chloride dihydride. In one embodiment the stannous ion source is
stannous
fluoride in another embodiment, stannous chloride dihydrate. The combined
stannous salts
may be present in an amount of from about 0.001% to about 11%, by weight of
the
compositions. The stannous salts may, in one embodiment, be present in an
amount of from
about 0.01% to about 7%, in another embodiment from about 0.1% to about 5%,
and in another
embodiment from about 1.5% to about 3%, by weight of the composition.
b-3) Fluoride Ion Source
Useful oral care agents herein include a fluoride ion source to provide an
anticaries
effect. Among these materials are inorganic fluoride salts, such as soluble
alkali metal fluoride
salts, for example, sodium fluoride, potassium fluoride, sodium
monofluorophosphate and
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sodium hexafluorosilicate. Alkali metal fluorides, such as sodium fluoride,
sodium
monofluorophosphate, sodium hexafluorosilicate and mixtures thereof, are
preferred.
The amount of fluorine-providing salt is generally present in the oral
composition at a
concentration of about 0.0 to about 3.0% by weight. Any suitable minimum
amount of such
salt may be used, but it is preferable to employ sufficient fluoride salt to
release from about
50ppm to about 3500 ppm, preferably from about 300ppm to 2,000ppm, of fluoride
ion.
b-4) Whiteninz Ment
Useful oral care agents herein include a whitening agent The actives suitable
for
whitening are selected from the group consisting of alkali metal and alkaline
earth metal
peroxides, metal chlorites, perborates inclusive of mono and tetrahydrates,
perphoshates,
percarbonates, peroxyacids, alkali metal and persulfates, such as ammonium,
potassium, sodium
and lithium persulfates, and combinations thereof. Suitable peroxide compounds
include
hydrogen peroxide, urea peroxide, calcium peroxide, carbamide peroxide,
magnesium peroxide,
zinc peroxide, strontium peroxide and mixtures thereof. In one embodiment the
peroxide
compound is carbamide peroxide. Suitable metal chlorites include calcium
chlorite, barium
chlorite, magnesium chlorite, lithium chlorite, sodium chlorite, and potassium
chlorite.
Additional whitening actives may be hypochlorite and chlorine dioxide. In one
embodiment
the chlorite is sodium chlorite. In another embodiment the percarbonate is
sodium
percarbonate. In one embodiment the persulfates are oxones. The level of these
substances is
dependent on the available oxygen or chlorine, respectively, that the molecule
is capable of
providing to bleach the stain. In one embodiment the whitening agents may be
present at levels
from about 0.01% to about 40%, in another embodiment from about 0.1% to about
20%, in
another embodiment form about 0.5% to about 10%, and in another embodiment
from about
4% to about 7%, by weight of the composition.
b-5) Anti-Microbial Ment
Useful oral care agents herein include other anti-microbial agents. Such
agents may
include, but are not limited to: 5-chloro-2-(2,4-dichlorophenoxy)-phenol,
commonly referred to
as triclosan; 8-hydroxyquinoline and its salts; copper II compounds,
including, but not limited to,
copper(II) chloride, copper(II) sulfate, copper(II) acetate, copper(II)
fluoride and copper(II)
hydroxide; phthalic acid and its salts including, but not limited to those
disclosed in U.S. Pat.
4,994,262, including magnesium monopotassium phthalate; chlorhexidine;
alexidine;
hexetidine; sanguinarine; benzalkonium chloride; salicylanilide; domiphen
bromide;
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cetylpyridinium chloride (CPC); tetradecylpyridinium chloride (TPC); N-
tetradecyl-4-
ethylpyridinium chloride (TDEPC); octenidine; iodine; sulfonamides;
bisbiguanides; phenolics;
delmopinol, octapinol, and other piperidino derivatives; niacin preparations;
zinc or stannous ion
agents such as zinc oxide, zinc lactate and zinc citrate; nystatin; grapefruit
extract; apple extract;
thyme oil; thymol; antibiotics such as augmentin, amoxicillin, tetracycline,
doxycycline,
minocycline, metronidazole, neomycin, kanamycin, cetylpyridinium chloride, and
clindamycin; analogs and salts of the above; essential oils including thymol,
geraniol, carvacrol,
citral, hinokitiol, eucalyptol, catechol (particularly 4-allyl catechol) and
mixtures thereof; methyl
salicylate; hydrogen peroxide; metal salts of chlorite; and mixtures of all of
the above. Anti-
microbial components may be present from about 0.001 Io to about 20% by weight
of the
composition.
b-6) Anti-Plaque Agent
Useful oral care agents herein include other anti-plaque agent such as
dimethyl
isosorbide, copper salts, strontium salts, magnesium salts or a dimethicone
copolyol. The
dimethicone copolyol is selected from C12 to C20 alkyl dimethicone copolyols
and mixtures
thereof. In one embodiment the dimethicone copolyol is cetyl dimethicone
copolyol marketed
under the Trade Name Abil EM90. The dimethicone copolyol in one embodiment can
be
present in a level of from about 0.001 Io to about 25 Io, in another
embodiment from about 0.01 Io
to about 5%, and in another embodiment from about 0.1% to about 1.5% by weight
of the
composition.
b-7) Anti-Inflammatory Agent
Useful oral care agents herein include anti-inflammatory agents. Such agents
may
include, but are not limited to, non-steroidal anti-inflammatory agents
oxicams, salicylates,
propionic acids, acetic acids and fenamates. Such NSAIDs include but are not
limited to
ketorolac, flurbiprofen, ibuprofen, naproxen, indomethacin, diclofenac,
etodolac, indomethacin,
sulindac, tolmetin, ketoprofen, fenoprofen, piroxicam, nabumetone, aspirin,
diflunisal,
meclofenamate, mefenamic acid, oxyphenbutazone, phenylbutazone and
acetaminophen. Use
of NSAIDs such as ketorolac are claimed in U.S. Patent 5,626,838. Disclosed
therein are
methods of preventing and/or treating primary and reoccurring squamous cell
carcinoma of the
oral cavity or oropharynx by topical administration to the oral cavity or
oropharynx of an
effective amount of an NSAID. Suitable steroidal anti-inflammatory agents
include
corticosteroids, such as fluccinolone, and hydrocortisone.
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b-8) Nutrients
Useful oral care agents herein include nutrients which improve the condition
of the oral
cavity. Nutrients include minerals, vitamins, oral nutritional supplements,
enteral nutritional
supplements, and mixtures thereof. Useful minerals include calcium,
phosphorus, zinc,
5 manganese, potassium and mixtures thereof. Vitamins can be included with
minerals or used
independently. Suitable vitamins include Vitamins C and D, thiamine,
riboflavin, calcium
pantothenate, niacin, folic acid, nicotinamide, pyridoxine, cyanocobalamin,
para-aminobenzoic
acid, bioflavonoids, and mixtures thereof. Oral nutritional supplements
include amino acids,
lipotropics, fish oil, and mixtures thereof. Amino acids include, but are not
limited to L-
10 Tryptophan, L-Lysine, Methionine, Threonine, Levocarnitine or L- carnitine
and mixtures
thereof. Lipotropics include, but are not limited to, choline, inositol,
betaine, linoleic acid,
linolenic acid, and mixtures thereof. Fish oil contains large amounts of Omega-
3 (N-3)
polyunsaturated fatty acids, eicosapentaenoic acid and docosahexaenoic acid.
Enteral
nutritional supplements include, but are not limited to, protein products,
glucose polymers, corn
oil, safflower oil, medium chain triglycerides. Minerals, vitamins, oral
nutritional supplements
and enteral nutritional supplements are described in more detail in Drug Facts
and Comparisons
(loose leaf drug information service), Wolters Kluer Company, St. Louis, Mo.,
(01997, pps. 3-
17 and 54-57.
b-9) Antioxidants
Useful oral care agents herein include antioxidants. Antioxidants are
disclosed in texts
such as Cadenas and Packer, The Handbook of Antioxidants, 1996 by Marcel
Dekker, Inc.
Antioxidants useful in the present invention include, but are not limited to,
Vitamin E, ascorbic
acid, Uric acid, carotenoids, Vitamin A, flavonoids and polyphenols, herbal
antioxidants,
melatonin, aminoindoles, lipoic acids and mixtures thereof.
b-10) Anti-Viral Ments
Useful oral care agents herein include an antiviral actives used to treat
viral infections.
Such antiviral actives include, but are not limited to: phosphonoformic acid;
cyosine derivatives;
purine analogues, such as adenosine, guanosine and inosine analogues;
pyrimidine bases, such as
citidine and thymidine; amantadines; rimantadine HC1; ribavirin; zanamivir;
oseltamivir
phosphate; trifluridine; heterocyclic dyes; acyclovir; famciclovir;
valacyclovir, cidofovir;
ganciclovir; levimisole; idoxuridine; lipophilic (3-ketones; and
thiosemicarbazones. These
antiviral actives are described in Drug Facts and Comparisons (loose-leaf drug
information
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service), Wolters Kluwer Company, St. Louis, Mo., 2001, pp. 1400-1423(b), and
in Kirk-
Othmer, Encyclopedia of Chemical Technology, Fourth Edition, Volume 3, Wiley-
Interscience
Publishers (1992), pp. 576-607.
b-11) Analgesic and Anesthetic Agents
Useful oral care agents herein include anti-pain or desensitizing agents.
Analgesics are
agents that relieve pain by acting centrally to elevate pain threshold without
disturbing
consciousness or altering other sensory modalities. Such agents may include,
but are not
limited to: strontium chloride; potassium nitrate; sodium fluoride; sodium
nitrate; acetanilide;
phenacetin; acertophan; thiorphan; spiradoline; aspirin; codeine; thebaine;
levorphenol;
hydromorphone; oxymorphone; phenazocine; fentanyl; buprenorphine; butaphanol;
nalbuphine;
pentazocine; natural herbs, such as gall nut; Asarum; Cubebin; Galanga;
scutellaria;
Liangmianzhen; and Baizhi. Anesthetic agents, or topical analgesics, such as
acetaminophen,
sodium salicylate, trolamine salicylate, lidocaine and benzocaine may also be
present. These
analgesic actives are described in detail in Kirk-Othmer, Encyclopedia of
Chemical Technology,
Fourth Edition, Volume 2, Wiley-Interscience Publishers (1992), pp. 729-737.
b-12) Zinc-containing Layered Material
Useful as the oral care active herein are zinc-containing layered material
which have
effective anti-microbial and anti-gingivitis benefit due to high zinc
lability. Those zinc-
containing layered materials particularly useful herein are those having a
relative zinc lability of
greater than about 25%, have an average particle size of less than about 20
microns, and have a
high surface area. In one preferred embodiment, the zinc-containing layered
material herein is
incorporated in compositions containing an anionic surfactant, as later
discussed.
Zinc lability is a measure of the chemical availability of zinc ion. Soluble
zinc salts that
do not complex with other species in solution have a relative zinc lability,
by definition, of
100%. The use of partially soluble forms of zinc salts and/or incorporation in
a matrix with
potential complexants generally lowers the zinc lability substantially below
the defined 100%
maximum. Labile zinc is maintained by choice of an effective zinc-containing
layered material
or formation of an effective zinc-containing layered material in-situ by known
methods.
Zinc lability is assessed by combining a diluted zinc-containing solution or
dispersion
with the metallochromic dye xylenol orange (XO) and measurement of the degree
of color
change under specified conditions. The magnitude of color formation is
proportional to the
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level of labile zinc. The procedure developed has been optimized for aqueous
surfactant
formulations but may be adapted to other physical product forms as well.
A spectrophotometer is used to quantify the color change at 572 nm, the
wavelength of
optimum color change for XO. The spectrophotometer is set to zero absorbance
at 572nm
utilizing a product control as close in composition to the test product except
excluding the
potentially labile form of zinc. The control and test products are then
treated identically as
follows. A 50 1 product sample is dispensed into a jar and 95 nil of
deaerated, distilled water
are added and stirred. 5mL of a 23mg/mL xylenol orange stock solution at pH
5.0 is pipetted
into the sample jar; this is considered time 0. The pH is then adjusted to 5.
50 0.01 using
dilute HC1 or NaOH. After 10.0 minutes, a portion of the sample is filtered
(0.45 ) and the
absorbance measured at 572nm. The measured absorbance is then compared to a
separately
measured control to determine the relative zinc lability (zero TO 100%). The
100% lability
control is prepared in a matrix similar to the test products but utilizing a
soluble zinc material
(such as zinc sulfate) incorporated at an equivalent level on a zinc basis.
The absorbance of the
100% lability control is measured as above for the test materials. The
relative zinc lability is
preferably greater than about 15%, more preferably greater than about 20%, and
even more
preferably greater than about 25%.
Using this methodology, the below examples demonstrate a material (basic zinc
carbonate) that has intrinsically high lability in an anionic surfactant
system compared to one
(ZnO) with low intrinsic lability.
Relative Zinc Lability (%) Lability Benefit
In Water In 6% sodium lauryl sulfate
Zinc Oxide 86.3 1.5 NO
Basic zinc carbonate 100 37 YES
Zinc-containing layered structures are those with crystal growth primarily
occurring in
two dimensions. It is conventional to describe layer structures as not only
those in which all
the atoms are incorporated in well-defined layers, but also those in which
there are ions or
molecules between the layers, called gallery ions (A.F. Wells "Structural
Inorganic Chemistry"
Clarendon Press, 1975). Zinc-containing layered materials (ZLM's) may have
zinc
incorporated in the layers and/or be components of the gallery ions.
Many ZLM's occur naturally as minerals. Common examples include hydrozincite
(zinc carbonate hydroxide), basic zinc carbonate, aurichalcite (zinc copper
carbonate hydroxide),
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13
rosasite (copper zinc carbonate hydroxide) and many related minerals that are
zinc-containing.
Natural ZLM's can also occur wherein anionic layer species such as clay-type
minerals (e.g.,
phyllosilicates) contain ion-exchanged zinc gallery ions. All of these natural
materials can
also be obtained synthetically or formed in situ in a composition or during a
production process.
Another common class of ZLM's, which are often, but not always, synthetic, is
layered
doubly hydroxides, which are generally represented by the formula [M2+1-
xM3+x(OH)2]x+
Am-x/m=nH2O and some or all of the divalent ions (M2+) would be represented as
zinc ions
(Crepaldi, EL, Pava, PC, Tronto, J, Valim, JB J. Colloid Interfac. Sci. 2002,
248, 429-42).
Yet another class of ZLM's can be prepared called hydroxy double salts
(Morioka, H.,
Tagaya, H., Karasu, M, Kadokawa, J, Chiba, K Inorg. Chem. 1999, 38, 4211-6).
Hydroxy
double salts can be represented by the general formula [M2+1-xM2+1+x(OH)3(1-
y)]+ An-
(1=3y)/n=nH2O where the two metal ion may be different; if they are the same
and represented
by zinc, the formula simplifies to [Znl+x(OH)2]2x+ 2x A-=nH2O. This latter
formula
represents (where x=0.4) common materials such as zinc hydroxychloride and
zinc
hydroxynitrate. These are related to hydrozincite as well wherein a divalent
anion replace the
monovalent anion. These materials can also be formed in situ in a composition
or in or during
a production process.
These classes of ZLM's represent relatively common examples of the general
category
and are not intended to be limiting as to the broader scope of materials which
fit this definition.
Commercially available sources of basic zinc carbonate include Zinc Carbonate
Basic
(Cater Chemicals: Bensenville, IL, USA), Zinc Carbonate (Shepherd Chemicals:
Norwood, OH,
USA), Zinc Carbonate (CPS Union Corp.: New York, NY, USA), Zinc Carbonate
(Elementis
Pigments: Durham, UK), and Zinc Carbonate AC (Bruggemann Chemical: Newtown
Square,
PA, USA).
Basic zinc carbonate, which also may be referred to commercially as "Zinc
Carbonate"
or "Zinc Carbonate Basic" or "Zinc Hydroxy Carbonate", is a synthetic version
consisting of
materials similar to naturally occurring hydrozincite. The idealized
stoichiometry is
represented by Zn5(OH)6(C03)2 but the actual stoichiometric ratios can vary
slightly and other
impurities may be incorporated in the crystal lattice.
c) Polar Solvent Carrier
The composition of the present invention comprises a polar solvent carrier for
delivering
the essential components, and for providing suitable rheology with the binder
system. The
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polar solvent also serves as solvent for incorporating water-soluble oral care
actives and other
components.
The polar solvent is comprised by weight of the entire composition at from
about 1% to
about 95%, preferably from about 30% to about 70%.
Polar solvents useful herein include water, polyhydric alcohols such as
glycerin, 1,3-
butylene glycol, propylene glycol, hexylene glycol, propane diol, ethylene
glycol, diethylene
glycol, dipropylene glycol, diglycerin, sorbitol, and other sugars which are
in liquid form at
ambient temperature. Also useful herein are water soluble alkoxylated nonionic
polymers such
as polyethylene glycol.
In one preferred embodiment, the present composition can comprise a relatively
high
level of water for providing a cost effective product. In such preferred
embodiment, water is
comprised at from about 30% to about 95%, more preferably from about 50 % to
about 70 % of
the entire composition.
Commercially available polar solvents herein include: glycerin available from
Asahi
Denka; propylene glycol with tradename LEXOL PG-865/855 available from Inolex,
1,2-
PROPYLENE GLYCOL USP available from BASF; 1,3-butylene glycol available from
Daisel
Kagaku Kogyo; dipropylene glycol with the same tradename available from BASF;
diglycerin
with tradename DIGLYCEROL available from Solvay GmbH, polyethylene glycol with
the
tradename PEG 300 available from Doe Chemical Company, and sorbitol 70%
solution
available from Khalista (Liuzhou) Chemical Industries, Ltd.
Abrasive Material
The composition of the present invention comprises a low level of, or
substantially no
abrasive material, preferably from 0% to about 10% abrasive material.
In one preferred embodiment, the present composition is substantially free of
abrasive
material. Namely, the composition of the present invention has no abrasive
material that is
intentionally included. It has been surprisingly found that, the embodiment of
the present
composition free of abrasive material can deliver the benefits of a regular
dentifrice
composition, including those which are typically attributed to the use of
abrasive material, such
as cleaning, stain removal, plaque removal, calculus removal, and others.
Absence of abrasive
material also accommodates inclusion of certain active agents such as
cetylpyridinium chloride,
which otherwise have poor compatibility with abrasive materials such as
silica, and therefore
cannot be included in a dentifrice composition. Further, due to the absence of
abrasive
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material, various aesthetics for the dentifrice product may be pursued. For
example, a
composition of transparent appearance may be made.
Abrasive materials, as meant in the present composition, are defined as
materials having
a DOA value of no more than about 150 mf/100g, preferably no more than about
100 mf/100g,
5 and having a particle size of about 5 m to about 50 m. Abrasive materials
herein can be
distinguished herein from those materials useful as binders.
Abrasive materials herein include: inorganic minerals such as silica gels and
precipitates;
aluminas; hydrated alumina, calcium carbonate, titanium dioxide, talc, calcium
dioxide, calcium
carbonate, and resinous abrasive materials such as particulate condensation
products of urea and
10 formaldehyde.
Phytic Acid Compound
The composition of the present invention may further comprise a phytic acid
compound
in an amount it provides effective cleaning to the teeth. Phytic acid, also
known as myo-
inositol hexaphosphate, or inositol hexaphosphoric acid, is a natural
vegetable based
15 biodegradable chelating agent in liquid form with chelating performance
comparable to that of
EDTA. Origin of vegetables from which phytic acid compounds can be found,
include cereal
grains, legumes, nuts oilseeds, pollen, spore, and organic soils.
The phytic acid compound herein can be phytic acid itself and/or its orally
acceptable
salts including, but not limited to, alkali metal salts and alkali earth metal
salts. Useful phytic
acid salts include sodium phytate, potassium phytate, magnesium phytate,
calcium phytate,
stannous phytate, zinc phytate, copper phytate, ferrum phytate, and mixtures
thereof.
It has been surprisingly found that the phytic acid compound provides good
cleaning
effect in the present low-abrasive or abrasive-free composition without
consumer noticeable
staining, and is compatible with the present polar solvent carrier, as well as
a wide variety of
oral care active ingredients. Without being bound by theory, it is believed
that the phytic acid
compound provides unique good cleaning due to its liquid form, by flowing
between teeth.
Such flowing is believed to provide cleaning in a way differently from solid
abrasive materials.
Further, it is believed that the phytic acid compound provides a positive
effect for protecting
tooth enamel from acid dissolution, and anti-tartar effect.
Commercially available phytic acid compounds useful herein include phytic acid
solution, sodium phytate, magnesium phytate, calcium phytate, and stannous
phytate available
from Sichuan Chengdu Yason, Shikishima Starch Manufacturing Company, and
Nibbio.
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Additional Components
The composition of the present invention may include other additional
components,
which may be selected by the artisan according to the desired characteristics
of the final product
and which are suitable for rendering the composition more cosmetically or
aesthetically
acceptable or to provide them with additional usage benefits. Such additional
components
generally are used individually at levels of no more than about 5% by weight
of the composition.
Surfactants may be incorporated in the components of the present invention as
an
ingredient to aid in the thorough dispersion of the dentifrice throughout the
oral cavity when
applied thereto, as well as, to improve cosmetic acceptability and the foaming
properties. The
surfactants which can be included in the present composition include anionic,
nonionic or
amphoteric compounds, anionic compounds being preferred.
Suitable examples of anionic surfactants are higher alkyl sulfates such as
potassium or
sodium lauryl sulfate which is preferred, higher fatty acid monoglyceride
monosulfates, such as
the salt of the monosulfated monoglyceride of hydrogenated coconut oil fatty
acids, alkyl
sulfonates such as sodium dodecyl benzene sulfonate, higher fatty
sulfoacetates, higher fatty acid
esters of 1,2 dihydroxypropane sulfonate.
Examples of amphoteric surfactans are alkylated betaine products such as
cocamidopropyl betaine with tradename TEGO Betaine ZF from Goldschmidt
Chemical Corp.
Examples of water soluble nonionic surfactants are condensation products of
ethylene
oxide with various hydrogen-containing compounds that are reactive therewith
and have long
hydrophobic chains (e.g., aliphatic chains of about 12 of 20 carbon atoms),
which condensation
products contain hydrophilic polyoxyethylene moieties, such as condensation
products of poly
(ethylene oxide) with fatty acids, fatty alcohols, fatty amides and other
fatty moieties, and with
propylene oxide and polypropylene oxides, e.g., Pluronic materials such as
Pluronic F127.
The surfactant can be present in the present composition at a concentration of
from about
0.5 to about 10.0% by weight, preferably about 1 to about 2% by weight.
Other ingredients which may be incorporated in the dentifrice components of
the present
invention include pigments, dyes, flavoring and sweentening materials. For
example, a striped
product is obtained in accordance with the present invention wherein colorants
of contrasting
colors are incorporated in each of the components used in the practice of the
present invention,
the colorants being pharmacologically and physiologically nontoxic when used
in the suggested
amounts. Colorants used in the present invention include both pigments and
dyes.
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Pigments useful in the present invention include non-toxic, water insoluble
inorganic
pigments such as titanium dioxide and chromium oxide greens, ultramarine blues
and pinks and
ferric oxides as well as water insoluble dye lakes prepared by extending
calcium or aluminum
salts of FD&C dyes on alumina such as FD&C Green #1 lake, FD&C Blue #21ake,
FD&C R&D
#30 lake, FD&C #5 Yellow and FD&C # Yellow 15 lake, The concentration of the
dye in the
present composition is no more than about 3% by weight. The pigments herein
are
distinguished from the abrasive materials, which the present composition is
substantially free
from, as pigments herein have a particle size in the range of from 100 to
about 1000 microns,
preferably from about 250 to about 500 microns. When present, the pigments are
included in
the present composition at from abomt 0.5 Io to about 3 Io by weight.
Any suitable flavoring or sweetening material may also be incorporated in the
components of the present invention. Examples of suitable flavoring
constituents are flavoring
oils, e.g., oils of spearmint, peppermint, wintergreen, sassafras, clove,
sage, eucalyptus,
marjoram, cinnamon. Lemon, and orange, and methyl salicylate. Suitable
sweetening agents
include sucrose, lactose, maltose, sorbitol, xylitol, sodium cyclamate,
perillartine, and sodium
saccharin. Suitably, flavor and sweentening agents may together comprise from
0.01% to 5%
by weight or more of the preparations.
Buffer agents such as monosodium phosphate and trisodium phosphate, enzyme
inhibitor, botanical extracts, natural herb extracts, and others may be
included.
EXAMPLES
The following dentifrice compositions are formed by the following components
using the
method of preparation described herein.
Compositions for Examples 1-5:
Component Ex.1 Ex. 2 Ex.3 Ex. 4 Ex.5
Sodium Fluoride *1 0.243 0.243 0.243 0.243 0.243
Sorbitol (70% sol.) *2 39.299 39.299 25 39.299
Glycerin 99.5% *3 5 20
Polyethylene Glycol *4 5
Sodium Lauryl Sulfate (28% sol.) *5 5 7.5 1 7.5 10
Sodium Carboxymethyl Cellulose *6 1.0 1.0 1.0 2.0
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Hydroxyethyl Cellulose *7 1.0
Carbopol * 8 0.6 0.6 1.0 0.6 1.0
Xanthan Gum * 9 0.35 0.5 0.35 1.0
Gellan Gum * 10 0.35
Carrageenan * 11 0.5
Synthesized Layered Magnesium 1.5 1.0 0.4 0.5
Silicate 0.2% Fluoride *12
Synthesized Layered Magnesium 0.2
Silicate *13
Amorphous Precipitated Silica * 14 0.5
Fumed Silica * 15 0.5
Precipitated Silica-abrasive * 16 2.5 5
Mica, Titanium Dioxide Coated * 17 0.5
Sodium Hydroxide Solution (50%) 0.54 0.54 0.54 0.54
*18
Tetrasodium Pyrophosphate * 19 0.05 0.05 0.05 0.05
Sodium phosphate, Monobasic, 0.4
Monohydrate *20
Tribasic Sodium Phosphate 0.9
(Dodecahydrate) *21
Flavor 0.80 0.80 0.50 0.80 1.00
Sodium Phytate 20% Solution *22 5.0 2.5 25.0 2.5 1.25
Sodium Saccharin *23 0.25 0.25 0.25 0.25 0.25
Dyes 0.0008 0.0008 0.0008 0.0008 0.0008
Deionized Water QS 100%
Compositions for Examples 6-10
Component Ex. 6 Ex. 7 Ex.8 Ex. 9 Ex. 10
Sodium Fluoride * 1 0.243 0.243 0.243
Stannous Fluoride *24 0.454 0.454
Sorbitol (70% sol.) *2 39.299 39.299 39.299 39.299 39.299
Sodium Lauryl Sulfate (28% sol.) *5 1 5 10
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Cocamidopropyl Betaine 30% 2.5 8
Solution *25
Sodium Carboxymethyl Cellulose *6 1.0 1.0 1.0 1.0 1.0
Carbopol * 8 0.6 0.6 0.6 0.6 0.6
Xanthan Gum * 9 0.35 0.35 0.35 0.35 0.35
Synthesized Layered Magnesium 0.2 0.2 0.2 0.2 0.2
Silicate 0.2% Fluoride *12
Precipitated Silica-abrasive * 16 2.5 5
Sodium Hydroxide Solution (50%) 0.54 0.54 0.54 0.54 0.54
*18
Flavor 0.80 0.80 0.75 0.75 0.75
Triclosan *26 0.28
Cetylpyridinium Chloride *27 0.045%
Zinc Carbonate *28 1.0
Sodium Phytate 20% Solution *22 17.5 2.5
Tetrasodium Pyrophosphate * 19 10 5
Dimethyl Isosorbide *29 5
Sodium Saccharin *23 0.25 0.25 0.25 0.25 0.25
Dyes 0.0008 0.0008 0.0008 0.0008 0.0008
Deionized Water QS 100%
Definition of Components
*1 Sodium Fluoride: NaF, available from Jinan Chemical Industry Co. Ltd.
*2 Sorbitol (70% sol.): Sorbitol 70% solution, available from Khalista
(Liuzhou) Chemicals
Industries Ltd.
*3 Glycerin 99.5%: Glycerin available from Asahi Denka
*4 Polyethylene Glycol: PEG-300, available from Doe Chemical Company
*5 Sodium Lauryl Sulfate (28% sol.): SLSS, available from Rhodia Specialty
Chemical Wuxi
Co. Ltd.
*6 Sodium Carboxymethyl Cellulose: CMC, available from Zhangjiagang city
Sanhui
Chemical Industry Co., Ltd
*7 Hydroxyethyl Cellulose: NATROSOL available from Hercules
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*8 Carbopol: Carbomer 956, available from Noveon, Inc.
*9 Xanthan Gum: KELDENT, available from CP Kelco Inc.
*10 Gellan Gum - by the tradename KELCOGEL series from CP Kelco
*11 Carrageenan: GELCARIN TP911 available from FMC Corporation food
ingredients
5 division
*12 Synthesized Layered Magnesium Silicate 0.2% Fluoride: LAPONITE DF,
available from
Rockwood Additives Limited
*13 Synthesized Layered Magnesium Silicate: LAPONITE D, available from
Rockwood
Additives Limited
10 * 14 Amorphous Precipitated Silica: Zeodent 165, available from J. M. Huber
Company
*15 Fumed Silica: AEROSOL, available from Cabot & Degussa Corporation
*16 Precipitated Silica-abrasive: Zeodent 119 and Zeodent 109 available from
J.M.Huber
Company
*17 Mica, Titanium Dioxide Coated: available from Rona
15 *18 Sodium Hydroxide Solution (50%): NaOH 50%, available from Guangzhou
Chemical
Company.
* 19 Tetrasodium Pyrophosphate: Sodium Pyrophosphate, Tetra (anhydrous),
available from
Lianyungang Duoling Fine Chemical Co. Ltd.
*20 Sodium Phosphate, Monobasic, Monohydrate: MSP, available from Jiangsu
Chengxing
20 Phosphate Chemical Co. Ltd
*21 Tribasic Sodium Phosphate: TSP, available from Jiangsu Jiangyin Phosph
Chemicals
*22 Sodium Phytate 20% Solution: available from Sichuan Chengdu Yason
*23 Sodium Saccharin: available from Suzhou Fine Chemical
*24 Stannous Fluoride: SnF2, available from Hashimoto
*25 Cocamidopropyl Betaine 30% Solution: TEGO Betaine ZF available from
Goldschmidt
Chemical Corp.
*26 Triclosan: available from Ciba-Geigy Chemicals Ltd.
*27 Cetylpyridinium Chloride: available from Cambrex company
*28 Zinc Carbonate: available from Bruggemann Chemical
*29 Dimethyl Isosorbide: Arlasolve DMI available from Uniqema.
Method of Preparation
The dentifrice compositions of Examples 1 - 10 may be made by any method known
to
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one skilled in the art, and are suitably prepared as follows.
First, the hydrophilic clay material (component number 12-14) is dispersed in
part of
water in a container at room temperature, using Propeller Mixer mix until
homogeneous. In a
separate main mix pot, sorbitol (component number 2), glycerin (component
number 3),
polyethylene glycol (component number 4), sodium hydroxide solution (component
number 18,
dye and pigment (component number 17) as present in the composition, and
remaining part of
water, are mixed together with an composition, are mixed together with an
agitator at 25 to
35rpm rotation speed at elevated temperature.
All remaining components except flavor and surfactants (component numbers 5
and 25)
are added to main mix pot. The pot is hermetically closed, vacuum is built to
around
100mmhg, homogenizer is turned at a rotation rate of 2400 to 3500rpm. The
obtained mixture
is further de-aerated.
To this is added the mixture made at first step. The obtained mixture is mixed
and de-
aerated. Finally, flavor and surfactants (component numbers 5 and 25) are
added, the pot is
again hermetically closed, mixed by homogenizer turned at a rotation rate of
2400 to 3500rpm
for final homogenization, and de-aerated.
The obtained product is pumped out of the container and delivered to a primary
packaging such as laminate tube.
The Example compositions herein have many benefits suitable for a dentifrice
product.
All compositions have a viscosity of between 10,000 and 450,000 Pas, provide
lower abrasion to
teeth surface, and are safer to teeth enamel compared to toothpastes
containing more than 10%
abrasive material. All compositions provide soft mouth feel, and easier
dispersion, and
improved approach in the between-teeth area compared to toothpastes containing
abrasive
material. All compositions provide better consumer noticeability of flavor as
compared to
toothpastes containing abrasive material and the same level of the same
flavor. Further, all
compositions can be manufactured at an economical cost. The compositions of
Examples 1-2
provide anti-caries, anti-plaque, whitening, anti-calculus, and anti-
gingivitis benefit. The
compositions of Examples 3-5, 7, and 10 provide anti-caries, anti-plaque,
whitening, and anti-
calculus benefit. The composition of Example 6 provides anti-caries, anti-
plaque, and
whitening benefit. The compositions of Examples 8-9 provide anti-caries, anti-
plaque,
whitening, anti-calculus, and anti-microbial benefit.
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The dimensions and values disclosed herein are not to be understood as being
strictly
limited to the exact numerical values recited. Instead, unless otherwise
specified, each such
dimension is intended to mean both the recited value and a functionally
equivalent range
surrounding that value. For example, a dimension disclosed as "40 mm" is
intended to mean
"about 40 mm".
All documents cited in the Detailed Description of the Invention are, in
relevant part,
incorporated herein by reference; the citation of any document is not to be
construed as an
admission that it is prior art with respect to the present invention. To the
extent that any
meaning or definition of a term in this written document conflicts with any
meaning or definition
of the term in a document incorporated by reference, the meaning or definition
assigned to the
term in this written document shall govern.
While particular embodiments of the present invention have been illustrated
and
described, it would be obvious to those skilled in the art that various other
changes and
modifications can be made without departing from the spirit and scope of the
invention. It is
therefore intended to cover in the appended claims all such changes and
modifications that are
within the scope of this invention.
