U.S. patent application number 09/840844 was filed with the patent office on 2001-09-13 for tooth whitening compositions.
This patent application is currently assigned to OraCeutical LLC. Invention is credited to Montgomery, R. Eric.
Application Number | 20010021374 09/840844 |
Document ID | / |
Family ID | 26746454 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010021374 |
Kind Code |
A1 |
Montgomery, R. Eric |
September 13, 2001 |
Tooth whitening compositions
Abstract
Novel compositions and methods are disclosed for cosmetically
treating teeth in a manner to increase brightness or shade of the
teeth. The compositions include a low molecular weight compound
having a high acetyl group functionality useful in the production
of a peroxy acid which then acts as a whitening agent.
Inventors: |
Montgomery, R. Eric;
(Monterey, MA) |
Correspondence
Address: |
BANNER & WITCOFF, LTD.
28 STATE STREET
28th FLOOR
BOSTON
MA
02109
US
|
Assignee: |
OraCeutical LLC
Monterey
MA
|
Family ID: |
26746454 |
Appl. No.: |
09/840844 |
Filed: |
April 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09840844 |
Apr 24, 2001 |
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09196403 |
Nov 19, 1998 |
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6221341 |
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60066187 |
Nov 19, 1997 |
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Current U.S.
Class: |
424/53 |
Current CPC
Class: |
A61K 8/375 20130101;
A61K 8/731 20130101; A61K 8/22 20130101; A61K 8/58 20130101; A61K
8/86 20130101; A61Q 11/00 20130101; A61K 8/8147 20130101; A61K 8/42
20130101; A61K 8/8182 20130101; A61K 8/39 20130101; A61K 8/8176
20130101; A61K 8/37 20130101 |
Class at
Publication: |
424/53 |
International
Class: |
A61K 007/20 |
Claims
What is claimed is:
1. An oral care composition for whitening teeth comprising: a
peroxyacetic acid generating mixture including a source of peroxide
and source of labile acyl groups, wherein the source of labile acyl
groups is a C.sub.1-C.sub.5 molecule having between 1 to 5 labile
C.sub.1-C.sub.5 acyl containing groups dispersed within an
anhydrous carrier.
2. The composition of claim 1 wherein the source of labile acyl
groups is a C.sub.1-C.sub.3 molecule having 1, 2, or 3 labile
acetyl groups.
3. The composition of claim 1 wherein the source of labile acyl
groups is selected from the group consisting of glyceryl
triacetate, glyceryl diacetate and glyceryl acetate.
4. A composition according to claim 1, wherein the source of
peroxide is selected from the group consisting of carbamide
peroxide, sodium percarbonate, sodium perborate, calcium peroxide,
magnesium peroxide, sodium peroxide, and anhydrous poly(vinyl
pyrrolidone)/hydrogen peroxide complexes.
5. A composition according to claim 1 capable of providing an oral
pH of more than 5.0 to generate peroxyacetic acid.
6. A composition according to claim 5, wherein the oral pH is
7.8.
7. The composition of claim 1 further including a carrier.
8. The composition of claim 7 wherein the carrier is selected from
the group consisting of glycerin, propylene glycol, polyethylene
glycols, chewing gum and gum base products, floss carriers and
floss wax products, oils, waxes and esters.
9. The composition of claim 1 further comprising a thickening
agent.
10. The composition of claim 9 wherein the thickening agent is
selected from the group consisting of neutralized
carboxypolymethylene, polyacrylic acid polymers and copolymers,
hydroxypropylcellulose and other cellulose ethers, salts of
poly(methyl vinyl ether-co-maleic anhydride),
poly(vinylpyrrolidone), poly(vinylpyrrolidone-co-vinyl acetate),
silicon dioxide, fumed silica, and stearic acid esters.
11. The composition of claim 1 further comprising a buffer.
12. The composition of claim 11 wherein the buffer is selected from
the group consisting of sodium hydroxide, potassium hydroxide,
ammonium hydroxide, sodium phosphate di- and tri-basic, potassium
phosphate di- and tri-basic, sodium tripolyphosphate,
tris(hydroxymethyl)aminomethane, triethanolamine, polyethylenimine,
polyacrylic acid, poly(methyl vinyl ether-co-maleic anhydride),
citric acid, and phosphoric acid.
13. The composition of claim 1 further comprising a surfactant.
14. The composition of claim 13 wherein the surfactant is selected
from the group consisting of zwitterionic and fluorinated
surfactants.
15. The composition of claim 1 further comprising a chelating
agent.
16. The composition of claim 15 wherein the chelating agent is
selected from the group consisting of phosphonic acids, EDTA, and
polyphosphates.
17. The composition of claim 1 further comprising flavorants or
sweeteners.
18. A composition for producing peroxyacetic acid for use in
whitening teeth, the composition comprising a two component system
including: a first component including a hydrogen peroxide
releasing compound and a second component including glyceryl
triacetate.
19. A method for whitening teeth comprising: forming a composition
by combining a hydrogen peroxide precursor, glyceryl triacetate,
and water so as to generate peroxyacetic acid; and applying the
composition to a tooth surface.
20. A method for whitening teeth comprising: applying one of either
a glyceryl triacetate or a hydrogen peroxide releasing compound
onto a tooth surface; and applying the other of the remaining
glyceryl triacetate or hydrogen peroxide releasing compound onto
the same tooth surface, so as to generate peroxyacetic acid upon
contact with an aqueous solution on the surface of the tooth.
21. A method for whitening teeth comprising: providing separately
glyceryl triacetate and a hydrogen peroxide releasing compound,
both in an orally safe and sufficient amount for whitening teeth;
forming a mixture between the glyceryl triacetate and the hydrogen
peroxide releasing compound; and applying the mixture onto a tooth
surface.
22. A method for cosmetically treating teeth comprising the steps
of: applying a source of labile acetyl groups onto the surface of a
tooth; allowing the source of labile acetyl groups to penetrate
into the tooth; applying a source of peroxide onto the surface of
the tooth; allowing the source of labile acetyl groups to react
with the source of peroxide anion to generate a peroxyacid within
the tooth; and allowing the peroxyacid to effect whitening of the
tooth.
23. The method of claim 22 wherein the source of labile acetyl
groups is a C.sub.1-C.sub.5 molecule having between 1 to 5 labile
C.sub.1-C.sub.5 acyl containing groups.
24. The method of claim 22 wherein the source of labile acetyl
groups has a molecular weight less than 1000.
25. The method of claim 22 wherein the source of labile acetyl
groups has a molecular weight less than 500.
26. The method of claim 22 wherein the source of labile acetyl
groups has a molecular weight of between about 100 to about
300.
27. The method of claim 22 wherein the source of labile acetyl
groups has a molecular weight approximate that of glyceryl
triacetate.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/066,187 filed Nov. 19, 1997.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention relate in general to
oral compositions, and more particularly, to tooth whitening
compositions.
[0004] 2. Description of Related Art
[0005] White teeth have long been considered cosmetically
desirable. Unfortunately, due to the presence of chromogenic
(color-causing) substances in food, beverages, tobacco, and
salivary fluid, in addition to internal sources such as blood,
amalgam restoratives, and antibiotics such as tetracycline, teeth
become almost invariably discolored in the absence of intervention.
The tooth structures that are generally responsible for presenting
a stained appearance are enamel, dentin, and the acquired pellicle.
Tooth enamel is predominantly formed from inorganic material,
mostly in the form of hydroxyapatite crystals, and further contains
approximately 5% organic material primarily in the form of
collagen. In contrast, dentin is composed of about 20% protein
including collagen, the balance consisting of inorganic material,
predominantly hydroxyapatite crystals, similar to that found in
enamel. The acquired pellicle is a proteinaceous layer on the
surface of tooth enamel which reforms rapidly after an intensive
tooth cleaning.
[0006] Staining of teeth results from extrinsic and/or intrinsic
staining. Extrinsic staining of the acquired pellicle arises as a
result of compounds such as tannins and other polyphenolic
compounds which become trapped in and tightly bound to the
proteinaceous layer on the surface of teeth. This type of staining
can usually be removed by mechanical methods of tooth cleaning. In
contrast, intrinsic staining occurs when staining compounds
penetrate the enamel and even the dentin, or alternatively arise
from sources within the tooth. This type of staining is not
amenable to mechanical methods of tooth cleaning and chemical
methods, which can penetrate into the tooth structure, are
required. Intrinsic tooth staining is generally more intractable
and difficult to remove than extrinsic tooth staining.
[0007] Consequently, tooth-bleaching compositions generally fall
into two categories: (1) gels, pastes, or liquids, including
toothpastes that are mechanically agitated at the stained tooth
surface in order to affect tooth stain removal through abrasive
erosion of stained acquired pellicle; and (2) gels, pastes, or
liquids that accomplish the tooth-bleaching effect by a chemical
process while in contact with the stained tooth surface for a
specified period, after which the formulation is removed. In some
cases, an auxiliary chemical process, which may be oxidative or
enzymatic, supplements the mechanical process.
[0008] Among the chemical strategies available for removing or
destroying tooth stains, the most effective compositions contain an
oxidizing agent, such as hydrogen peroxide, in order to attack the
chromogen molecules in such a way as to render them colorless,
water-soluble, or both. In one of the most popular approaches to
whitening a patient's teeth, a dental professional will construct a
custom made dental bleaching tray for the patient from an
impression made of the patient's dentition and prescribe the use of
an oxidizing gel to be dispensed into the bleaching tray and worn
intermittently for a period of from about 2 weeks to about 6
months, depending upon the severity of tooth staining. These
oxidizing compositions, usually packaged in small plastic syringes
or tubes, are dispensed directly by the patient into the
custom-made tooth-bleaching tray, held in place in the mouth for
contact times of greater than about 60 minutes, and sometimes as
long as 8 to 12 hours. The slow rate of bleaching is in large part
the consequence of the very nature of formulations that are
developed to maintain stability of the oxidizing composition. The
most commonly used oxidative compositions contain the hydrogen
peroxide precursor carbamide peroxide which is mixed with an
anhydrous or low-water content, hygroscopic viscous carrier
containing glycerin and/or propylene glycol and/or polyethylene
glycol. When contacted by water, carbamide peroxide dissociates
into urea and hydrogen peroxide. Associated with the slow rate of
bleaching in the hygroscopic carrier, the currently available
tooth-bleaching compositions cause tooth sensitization in over 50%
of patients. Tooth sensitivity is believed to result from the
movement of fluid through the dentinal tubules, which is sensed by
nerve endings in the tooth. The carriers for the carbamide peroxide
enhance this movement. In fact, it has been determined that
glycerin, propylene glycol and polyethylene glycol can each give
rise to varying amounts of tooth sensitivity following exposure of
the teeth to heat, cold, overly sweet substances, and other
causative agents.
[0009] Prolonged exposure of teeth to bleaching compositions, as
practiced at present, has a number of adverse effects in addition
to that of tooth sensitivity. These include: solubilization of
calcium from the enamel layer at a pH less than 5.5 with associated
demineralization; penetration of the intact enamel and dentin by
the bleaching agents, so as to reach the pulp chamber of a vital
tooth thereby risking damage to pulpal tissue; and dilution of the
bleaching compositions with saliva resulting in leaching from the
dental tray and subsequent ingestion.
[0010] Alternatively, there are oxidizing compositions (generally
those with relatively high concentrations of oxidizers) which are
applied directly to the tooth surface of a patient in a dental
office setting under the supervision of a dentist or dental
hygienist. Theoretically, such tooth whitening strategies have the
advantage of yielding faster results and better overall patient
satisfaction; however, due to the high concentration of oxidizing
agents contained in these so called "in-office" compositions, they
can be hazardous to the patient and practitioner alike if not
handled with care. The patient's soft tissues (the gingiva, lips,
and other mucosal surfaces) must first be isolated from potential
exposure to the active oxidizing agent by the use of a perforated
rubber sheet (known as a rubber dam), through which only the teeth
protrude. Alternatively, the soft tissue may be isolated from the
oxidizers to be used in the whitening process by covering said soft
tissue with a polymerizable composition that is shaped to conform
to the gingival contours and subsequently cured by exposure to a
high intensity light source. Once the soft tissue has been isolated
and protected, the practitioner may apply the oxidizing agent
directly onto the stained tooth surfaces for a specified period of
time or until a sufficient change in tooth color has occurred.
Typical results obtained through the use of a in-office tooth
whitener, with or without activation by heat, range from about 2 to
3 shades (as measured with the VITA Shade Guide, VITA
Zahnfarbik).
[0011] The range of tooth shades in the VITA Shade Guide varies
from very light (B1) to very dark (C4). A total of 16 tooth shades
constitute the entire range of colors between these two endpoints
on a scale of brightness. Patient satisfaction with a tooth
whitening procedure increases with the number of tooth shade
changes achieved, with a generally accepted minimum change
desirable of about 4 to 5 VITA shades.
[0012] Of the many peroxides available to the formulator of tooth
whitening compositions, hydrogen peroxide (and its adducts or
association complexes, such as carbamide peroxide and sodium
percarbonate) has been used almost exclusively. The chemistry of
hydrogen peroxide is well known, although the specific nature of
its interactions with tooth chromogens is poorly understood. It is
believed that hydrogen peroxide destroys tooth chromogens in a
similar fashion to that observed in the destruction of laundry
stains, that is, by oxidizing unsaturated carbon-carbon,
carbon-oxygen, and carbon-nitrogen bonds found in the stain
molecules. A related class of compounds, the peroxyacids, has been
used in laundry detergents to effectively whiten clothes, due
primarily to their stability in solution and their specific binding
abilities to certain types of stain molecules. A number of stable,
solid peroxyacids have been used, including diperoxydodecanoic acid
and the magnesium salt of monoperoxyphthalic acid. Other
peroxyacids, such as peroxyacetic acid, are available as solutions
containing an equilibrium distribution of acetic acid, hydrogen
peroxide, peroxyacetic acid and water. Alternatively, a peroxide
donor such as sodium perborate or sodium percarbonate is formulated
into a dry laundry detergent, together with a peroxyacid precursor.
Upon contact with the wash water, the peroxide donor releases
hydrogen peroxide into the wash solution, which then reacts with
the peroxyacid precursor to form the actual peroxyacid. Examples of
peroxyacids created in situ include peroxyacetic acid (from
hydrogen peroxide and tetraacetylethylenediamine) and
peroxynonanoic acid (from hydrogen peroxide and nonanoyloxybenzene
sulfonate).
[0013] It is recognized in the art that the water solubility of the
peroxyacid precursor is critical to the performance of a particular
detergent composition. For example, rapidly soluble peroxyacid
precursors tend to release the peroxyacid too quickly into
solution, and as a result, may damage or not effectively clean the
clothes being washed. Peroxyacid precursors that are slowly soluble
in water, on the other hand, tend to give a prolonged and
controlled release of peroxyacid into the wash water during the
laundering cycle, and as a result, may more effectively clean
clothing.
[0014] Peroxyacids have been used in oral care compositions to
whiten stained teeth. U.S. Pat. No. 5,279,816 discloses a method of
whitening teeth comprising the application of a peroxyacetic
acid-containing composition having an acid pH. EP 545,594 A1
discloses the use of peroxyacetic acid in preparing a composition
for whitening teeth. The peroxyacetic acid may be present in the
composition, or in the alternative, may be generated in situ by
combining a peroxide source with a peroxyacetic acid precursor
during use. U.S. Pat. No. 5,302,375 discloses a composition that
generates peroxyacetic acid within a vehicle in situ by combining
water, acetylsalicylic acid and a water soluble alkali metal
percarbonate.
BRIEF SUMMARY OF THE INVENTION
[0015] Embodiments of the present invention are directed to
compositions and methods useful in cosmetically treating teeth in a
manner to improve the brightness or shade of the teeth. Embodiments
of the present invention are also directed to compositions having
antimicrobial activity for use in the therapeutic treatment of
teeth. According to one embodiment of the present invention, a
method is described whereby a composition is provided which upon
contact with an aqueous medium or environment generates
peroxyacetic acid for use as an oxidant in the tooth-whitening or
stain removal process. Embodiments of the present method invention
advantageously utilize compounds capable of generating peroxyacids
quickly and effectively for application to teeth as compared to
prior art compounds.
[0016] The methods of the present invention employ compositions
including at least one orally acceptable acyl group source or
precursor and at least one orally acceptable peroxide source or
precursor. The acyl group source and the peroxide precursor, upon
contact with an aqueous solution, generate a peroxyacid. The acyl
group source and the peroxide precursor may be dispersed within an
anhydrous carrier.
[0017] According to one embodiment of the present invention, the
acyl group source is an acetyl group source being a low molecular
weight molecule having at least one acetyl group to be used in the
formation of a peroxy acid. According to this embodiment, the
acetyl group source has a molecular weight and steric configuration
that allows the acetyl group source to penetrate pores present in
teeth after application of the acetyl group source. Once the acetyl
group source has penetrated a tooth, a peroxide source can then be
used to generate a peroxyacid within a tooth rather than only on
the surface of the tooth. More efficient and greater whitening
capabilities are achieved by using such acetyl group sources
capable of penetrating pores in teeth.
[0018] According to a specific embodiment of the present invention,
the acetyl group source is a low molecular weight C.sub.1-C.sub.5
molecule having between 1 and 5 labile acetyl groups. In a acetyl
groups. It is to be understood that labile functional groups having
similar properties to acetyl groups are considered to be within the
scope of the present invention, i.e. all that is required is that
the active group be capable of forming an agent useful in the
whitening or stain removal of teeth, such as a peroxyacid. Such
labile functional groups include C.sub.1-C.sub.5 acyl containing
groups.
[0019] According to one embodiment of the present invention, the
composition includes at least two components: one component
including a source of peroxide (such as hydrogen peroxide), and a
second component including a source of acetyl groups. The two
components may be mixed together prior to application of the
resulting mixture to the tooth surface. Alternatively, each
component may be sequentially applied directly to the tooth
surface. It should be noted that either of the components may be
applied first before the application of the remaining
component.
[0020] One object of the present invention, therefore, is to
provide a novel composition which quickly and effectively produces
a peroxyacid in an amount sufficient to whiten teeth. Another
object of the present invention is to provide a method whereby a
peroxyacid generating species is allowed to penetrate into the
tooth and beyond the tooth surface where staining compounds may be
present and then generating a peroxyacid or other tooth-whitening
species within the tooth to provide a greater tooth whitening
effect.
[0021] Other objects, features and advantages of certain
embodiments of the present invention will become more fully
apparent from the following description taken in conjunction with
the accompanying claims.
DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS
[0022] The principles of the present invention may be applied with
particular advantage to obtain compositions and methods for the
whitening or stain removal of teeth. The present invention, in one
embodiment, is directed to a composition that whitens the color of
teeth when applied to a stained tooth surface. The composition may
be provided as a multi-component formulation including a peroxide
source and a source of acetyl or functionally similar groups, which
when combined produces an active ingredient useful in teeth
whitening, such as a peroxyacid. According to one embodiment, the
peroxide source is hydrogen peroxide or a hydrogen peroxide
percurser and the source of acetyl or functionally similar groups
is a C.sub.1-C.sub.5 molecule having between 1 to 5 labile
C.sub.1-C.sub.5 acyl containing groups.
[0023] Alternatively, in order to prevent premature reaction of the
hydrogen peroxide or its precursor with the source of acetyl
groups, an anhydrous formulation containing both the source of
acetyl groups and hydrogen peroxide or its precursor is provided.
The hydrogen peroxide or its precursor, and the the source of
acetyl groups, upon placement against the stained tooth surface in
the oral cavity, are activated by the aqueous content of the saliva
to generate a peroxacid, such as peroxyacetic acid.
[0024] Alternatively, a composition may be manufactured having each
of the hydrogen peroxide or its precursor and the source of acetyl
groups as a separate and distinct component. According to this
aspect of the invention, one component containing the source of
acetyl groups may be applied to a stained tooth surface followed
immediately thereafter by application onto the same tooth surface
of a second component containing hydrogen peroxide or a hydrogen
peroxide precursor. The sequence of application of such components
may also be reversed depending upon the desired application. Such a
sequential application would provide for the production of
peroxyacetic acid in situ and is advantageously beneficial to
accessing chromogens in tooth structures.
[0025] According to an additional aspect of the present invention,
the first component containing a source of acetyl groups is applied
to the tooth and is allowed for a sufficient time period to
penetrate into pores present in the tooth structure. The second
component containing the peroxide precursor is then applied which
then advantageously provides for the generation of peroxyacid at
locations deep within the tooth structure to thereby interact with
chromogens that may also be within the tooth structure resulting in
enhanced tooth whitening.
[0026] The hydrogen peroxide precursor for use in connection with
the present invention is preferably selected from the group
consisting of carbamide peroxide, sodium percarbonate, sodium
perborate, calcium peroxide, magnesium peroxide, sodium peroxide,
and the anhydrous poly(vinyl pyrrolidone)/hydrogen peroxide
complexes. It is contemplated that any compound which, when in
contact with water, is capable of generating, converting to, or
otherwise becoming hydrogen peroxide or peroxide anion, will have
utility in the formulation of the present inventive compositions.
For instance, it is possible to utilize other alkali metal
percarbonates (such as potassium percarbonate), as well as
enzymatic sources of hydrogen peroxide, such as glucose oxidase in
combination with beta-D-glucose. Additional useful peroxide
precursors will become apparent to those skilled in the art based
upon the present disclosure.
[0027] The peroxide precursor is present in the compositions of the
present invention as they are applied directly to the tooth surface
in an amount sufficient to result in a hydrogen peroxide
concentration of from about 0.1 percent by weight to about 15
percent by weight. Higher levels of hydrogen peroxide may be used
in conjunction with a supervised dental whitening procedure in
which the soft tissue (i.e., the gingival and other mucosal
surfaces) are physically isolated from the teeth being whitened.
Hydrogen peroxide concentrations up to about 3 percent are
acceptable for short-term (less than 60 minutes) incidental contact
with soft tissue.
[0028] Compositions that utilize hydrogen peroxide itself, rather
than a precursor, should be prepared as two or more components,
keeping the source of acetyl groups in one component and hydrogen
peroxide in the second component as an aqueous solution containing
both hydrogen peroxide and the source of acetyl groups will quickly
form a peroxyacid.
[0029] The source of labile acetyl groups of the present invention
is a C.sub.1-C.sub.5 molecule having between 1 to 5 labile
C.sub.1-C.sub.5 acyl containing groups. According to a preferred
embodiment, the source of labile acetyl groups is a C.sub.1-C.sub.3
molecule having 1, 2, or 3 acetyl groups. According to a specific
preferred embodiment of the present invention, the source of labile
acetyl groups is glyceryl triacetate, glyceryl diacetate or
glyceryl acetate. The source of labile acetyl groups is present in
the compositions of the present invention in an amount sufficiently
high to allow for the rapid generation of peroxyacid, i.e. in an
amount between about 0.1 percent by weight to about 6.0 percent by
weight of the composition.
[0030] Glyceryl triacetate (CAS No. 102-76-1) has a molecular
weight of about 218.20 and is available as a colorless, oily liquid
with a slight fatty odor. It is soluble in water up to a
concentration of approximately 7.1% by weight in water and is
generally prepared by the acetylation of glycerol. Glyceryl
triacetate has an extremely low order of toxicity and is listed as
GRAS (Generally Regarded as Safe as a direct food additive) in the
Code of Federal Regulations, Title 21, Part 184.1901. It is
therefore ideally suited for use in oral care products.
[0031] The use of glyceryl triacetate is advantageous due to its
highly labile acetyl functionalities (which is important to
obtaining effective tooth whitening levels of peroxyacetic acid in
the presence of hydrogen peroxide), its low level of oral toxicity,
and its unexpected ability to penetrate into intact tooth enamel
upon contact to a tooth surface. Additionally, glyceryl triacetate
degrades, in the presence of peroxide, into acetic acid (after
first converting to peroxyacetic acid), water, and other
degradation products that are toxicologically acceptable.
[0032] While not wishing to be bound to any particular theory, the
tightly packed crystal structure of tooth enamel and, to a lesser
degree, dentin renders the tooth relatively impermeable to high
molecular weight compounds such as proteins and polysaccharides. In
addition, both the hydroxyapatite crystals and their supporting
collagen matrix act as permselective barriers to diffusion of many
types of molecules. In particular, highly polar or strongly charged
ionic species (such as amines and glycols) do not penetrate the
tooth structure to the same degree as relatively non-polar or
uncharged species. The source of labile acetyl groups
advantageously has a sufficiently low molecular weight which allows
it to penetrate pores within teeth. Suitable compounds will have
molecule weights below 1000, preferably below 500 and most
preferably in a range similar to glyceryl triacetate, i.e. between
300 and 100.
[0033] It should be noted that the use of slowly or minimally
soluble peroxyacid precursors in connection with the composition of
the present invention is also useful in applications where the need
for immediate release or generation of the peroxyacid just prior to
or during use is not required.
[0034] According to an additional embodiment, the pH of the tooth
whitening composition may be controlled during use as the
generation of peroxyacid from hydrogen peroxide and glyceryl
triacetate is pH-dependent.
[0035] The composition of the present invention may be applied to
the stained tooth surface as liquids, gels, pastes, sprays, or as
solid delivery systems (for instance, chewing gum or dental floss).
The composition may be applied to the tooth surface in the form of
a single component anhydrous formulation, a multi-component
anhydrous or aqueous formulation mixed prior to application, or a
multi-component anhydrous or aqueous formulation mixed directly on
the tooth surface by sequential application of two or more
components.
[0036] The peroxyacids of the present invention advantageously
possess a high degree of antimicrobial activity. Accordingly, the
compositions of the present invention are envisioned to have useful
antimicrobial activity in addition to the desired tooth whitening
effects. This activity may cause the destruction of oral
microorganisms responsible for the formation of plaque (and
eventually tartar), thus adding significantly to the potential
utility of the present invention.
[0037] In one embodiment, the single component composition remains
relatively anhydrous to prevent premature generation of
peroxyacetic acid from the interaction of hydrogen peroxide with
glyceryl triacetate in aqueous solution. As the composition is
anhydrous, it is necessary to utilize a hydrogen peroxide
precursor, such as those provided above, which is not only soluble
or dispersible, but stable in the carrier.
[0038] Carriers for inventive single component compositions should
be toxicologically benign and include glycerin, propylene glycol,
and polyethylene glycols. Such carriers may include chewing gum and
gum base products, and floss carriers and floss wax products. An
oil-based carrier is also useful, especially when combined with a
surfactant capable of emulsifying the composition upon contact with
water. Such oils include both vegetable and mineral oils, in
addition to their higher molecular weight counterpart waxes and
esters. Carriers for multi-component compositions include all of
the above in addition to water. It is to be understood that
additional useful carriers will become apparent to those skilled in
the art based upon the disclosure herein. The carrier portion of
the inventive compositions, which may be composed of one or more
individual components, and which may include such components as
thickeners, buffering compounds, chelating agents, stabilizers,
surfactants, sweeteners, and flavorants, is present at a level of
from about 79 percent of the composition (in the form as it is
applied to the tooth surface) to about 99.8 percent of the
composition.
[0039] A thickener may also be added to increase contact time of
either the single or multi-component composition on the tooth
surface. This is particularly useful in tooth whitening methods
where a dental tray is used to confine the material to a patient's
dentition. Thickeners such as neutralized carboxypolymethylene and
other polyacrylic acid polymers and copolymers,
hydroxypropylcellulose and other cellulose ethers, salts of
poly(methyl vinyl ether-co-maleic anhydride),
poly(vinylpyrrolidone), poly(vinylpyrrolidone-co-vinyl acetate),
silicon dioxide, fumed silica, stearic acid esters, and others are
found to have utility in the formulation of tooth whitening
compositions. The level of thickener, when present, is highly
dependent upon the type chosen, but in general is included in the
composition at a concentration of from about 0.5 percent by weight
to about 20.0 percent by weight of the composition. It is to be
understood that additional useful thickeners will become apparent
to those skilled in the art based upon the disclosure herein.
[0040] The compositions of the present invention may also contain a
buffer to provide a specific pH for optimal penetration of the
composition into tooth enamel or to provide for optimal generation
of peroxyacetic acid from the hydrogen peroxide precursor and
glyceryl triacetate. Suitable buffers include sodium hydroxide,
potassium hydroxide, ammonium hydroxide, sodium phosphate di- and
tri-basic, potassium phosphate di- and tri-basic, sodium
tripolyphosphate, tris(hydroxymethyl)aminomethane, triethanolamine,
polyethylenimine, and other alkaline buffers. Within a particular
formulation, an alkaline buffer may also serve the purpose of
neutralizing carboxylic acid side chains in thickening polymers
such as polyacrylic acid and poly(methyl vinyl ether-co-maleic
anhydride). Acid buffers, such as citric acid, phosphoric acid, and
others may also be used alone or in conjunction with an alkaline
buffer to obtain the desirable pH and to provide buffering
capacity. The level of buffer, when present, is from about 0.5
percent by weight to about 3.0 percent by weight of the
composition. It is to be understood that additional useful buffers
will become apparent to those skilled in the art based upon the
disclosure herein.
[0041] The formation of peroxyacetic acid from hydrogen peroxide
and glyceryl triacetate has been determined to occur most readily
at pH levels in excess of about 5.2. However, peroxyacetic acid is
only stable at an acid pH if formulated fully within a composition.
Therefore, it is seen to be preferred to provide compositions that
generate peroxyacetic acid in situ at a pH more suited to producing
it quickly for use in the oral cavity. In this manner, tooth stains
can be removed at a much more rapid rate through the use of the
present compositions.
[0042] Compositions of the present invention may optionally contain
one or more chelating agents for the purpose of scavenging metal
ions in the composition and during use of the composition. Metals,
such as iron, manganese, and copper, and their oxides are known in
the art to cause the degradation of hydrogen peroxide through
Fenton-type reactions. This particular degradation mechanism is
undesirable in that the hydroxyl free radical (OH.circle-solid.) is
created and is not as effective as the perhydroxyl anion (HOO--) in
attacking chromogens. Therefore, it is desirable to encourage the
dissociation of hydrogen peroxide into perhydroxyl anions, rather
than hydroxyl radicals, in order to maximize the effectiveness of
the inventive compositions. It may also be desirable to provide
conditions in the inventive compositions which are conducive to the
formation of peroxyacetic acid (CH3COOOH) and its dissociated
species, the peroxyacetate anion (CH3COOO--). In a similar fashion
as above, the peroxyacetate anion is much more effective as a
bleaching or whitening agent than free radical species, such as the
peroxyacetyl radical (CH3COOO.circle-solid.), which form in the
presence of metal ions and their oxides.
[0043] Although virtually any chelating agent capable of
sequestering metal ions in aqueous solution may be advantageously
employed for the purpose above, particularly useful chelating
agents are selected from the group of phosphonic acids, EDTA, and
polyphosphates. In particular,
1,1-dihydroxethyliene-1-disphosphonic acid (sold by the Monsanto
Corp under the trade name Dequest 2010) is seen to provide the
desired metal chelating abilities, thereby protecting against free
radical formation through Fenton-type reactions. The phosphonic
acids are particularly suitable as chelating agents due to their
excellent stability in the presence of peroxides. The level of
chelating agent, when present, is from about 0.01 to about 5.0
percent by weight of the composition. It is to be understood that
additional useful chelating agents will become apparent to those
skilled in the art based upon the disclosure herein.
[0044] Surface active agents (surfactants) may be used to lower the
surface tension of the compositions. Lowering of the surface
tension allows for better wetting and spreading of the composition
on the tooth surface. Some surfactants, such as zwitterionic and
fluorinated surfactants, have been seen to increase the penetration
of the present inventive compositions into the tooth structure.
Useful surfactants include those identified in U.S. Pat. No.
5,279,816 and U.S. Pat. No. 5,302,375 each incorporated herein by
reference in its entirety. It is to be understood that additional
useful surfactants will become apparent to those skilled in the art
based upon the disclosure herein. The level of surfactant, when
present, is from about 0.1 to about 2.0 percent by weight of the
composition.
[0045] Flavorants may also be included in the oral composition in
order to improve palatability and acceptance by the patient or
consumer. Flavorants are generally known in the art and include,
among others, spearmint, peppermint, anethole, menthol, citrus
flavors, and vanilla. It may be desirable to provide within the
composition an artificial sweetener selected from the group of
sodium saccharin and potassium acesulfame. Both flavorants and
sweeteners, when present, are each included at a level of from
about 0.05 to about 1.5 percent by weight of the composition. Other
artificial sweeteners are contemplated to have utility in the
practice of the present invention, limited only by their solubility
and stability in the compositions.
[0046] Other ingredients may also be added to the compositions of
the present invention such as pyrophosphate salts, peroxide
stabilizers, soluble and insoluble calcium compounds disclosed in
U.S. Pat. No. 5,279,816 and U.S. Pat. No. 5,302,375. In addition,
antimicrobial compounds may also be added to the compositions of
the present invention in amounts sufficient to have an
antimicrobial effect.
[0047] The following examples are set forth as representative of
the present invention. These examples are not to be construed as
limiting the scope of the invention as these and other equivalent
embodiments will be apparent in view of the present disclosure,
tables and accompanying claims.
EXAMPLE I
[0048] In order to determine the ability of the inventive
compositions to eliminate tooth stain, a preliminary in vitro study
on stained bovine enamel was performed.
[0049] Squares of dental enamel 4 mm on a side were cut, using a
diamond-cutting disk, from bovine permanent incisors. Using a mold,
the enamel squares were embedded in clear polyester casting resin
(NATCOL Crafts Inc., Redlands, Calif.) to provide 1.5 cm square
blocks with the labial surface exposed. The top surface of the
polyester blocks was ground flush with the leveled labial surface
of the enamel squares by means of a dental model trimmer. The
surface was then smoothed by hand sanding on 400-grit emery paper
using water as the lubricant until all grinding marks were removed.
Finally, the top surface of the blocks was hand polished to a
mirror finish using a water slurry of GK1072 calcined kaolin
(median particle size=1.2 microns) on a cotton cloth. The finished
specimens were examined under a dissecting microscope and were
discarded if they had surface imperfections.
[0050] In preparation for the formation of artificial stained
pellicle on the enamel, the specimens were etched for 60 seconds in
0.2M HCl followed by a 30-second immersion in a saturated solution
of sodium carbonate. A final etch was performed with 1% phytic acid
for 60 seconds, then the specimens were rinsed with deionized water
and attached to the staining apparatus.
[0051] The pellicle staining apparatus was constructed to provide
alternate immersion into the staining broth and air-drying of the
specimens. The apparatus consisted of an aluminum platform base
which supported a Teflon rod (3/4 inch in diameter) connected to an
electric motor, which by means of a speed reduction box, rotated
the rod at a constant rate of 1.5 rpm. Threaded screw holes were
spaced at regular intervals along the length of the rod. The tooth
specimens were attached to the rod by first gluing the head of a
plastic screw to the back of a specimen. The screw is then
tightened within a screw hole in the rod. Beneath the rod was a
removable, 300-ml capacity trough, which held the pellicle,
staining broth.
[0052] The pellicle staining broth was prepared by adding 1.02
grams of instant coffee, 1.02 grams of instant tea, and 0.75 grams
of gastric mucin (Nutritional Biochemicals Corp., Cleveland, Ohio
44128) to 250 ml of sterilized trypticase soy broth. Approximately
50 ml of a 24-hour Micrococcus luteus culture was also added to the
stain broth. The apparatus, with the enamel specimens attached and
the staining broth in the trough was then placed in an incubator at
37.degree. C. with the specimens rotating continuously through the
staining broth and air. The staining broth was replaced once every
24 hours for ten consecutive days. With each broth change the
trough and specimens were rinsed and brushed with deionized water
to remove any loose deposits. On the eleventh day the staining
broth as modified by the addition of 0.03 grams of
FeCl.sub.3.circle-solid.6H.sub.2O, and this was continued with
daily broth changes until the stained pellicle film on the
specimens was sufficiently dark. Then the specimens were removed
from the staining broth, brushed thoroughly with deionized water,
and refrigerated in a humidor until used.
[0053] Absorbance measurements over the entire visible spectrum
were obtained using the CIELAB color scale (Commission
International de L'Eclairage, Recommendations on uniform color
spaces, color difference equations, and psychometric color terms,
Supplement 2 to CIE publication 15 (E-13.1) 1971 (TC-1.3), 1978,
Paris: Beaurea Central de la CIE, 1978). The CIELAB color scale
evaluates color in terms of three axes of a color sphere, called L,
a, and b. The "L" value is the axis in the color sphere which
relates lightness and darkness on a scale from 0 (black) to 100
(white). The "a" value is the axis which relates color on a yellow
to blue scale, with a 0 value in the center of the sphere, positive
values toward the yellow, and negative values toward the blue. The
"b" value is the axis which relates color on a red to green scale,
with a 0 value in the center of the sphere, positive values toward
the red, and negative values toward the green.
[0054] The stained enamel specimens were allowed to air-dry at room
temperature for at least one hour before absorbance measurements
were made. Measurements were conducted by aligning the center of a
4-mm square segment of stained enamel directly over the 3-mm
aperture of the Minolta spectrophotometer. An average of 3
absorbance readings using the L*a*b* factors were taken for each
specimen.
[0055] The difference between the pre-treatment (baseline) and
post-treatment readings for each color factor (L*, a*, and b*)
represented the ability of a test solution to eliminate chromogens
from the stained teeth.
[0056] The overall change in color of stained pellicle was
calculated using the CIELAB equation
.DELTA.E=[(.DELTA.L*).sup.2+(.DELTA.a*).sup.2+(.DELTA.b*).sup.2].sup.1/2
[0057] The individual components of the L*a*b* scale were also
analyzed separately to determine the specific changes in lightness,
redness, and yellowness, respectively.
[0058] Two solutions, A and B, were prepared from a stock solution
of 10% hydrogen peroxide adjusted to a pH of 5.20 with 10% NaOH.
Solution A was the same as the stock solution of 10% hydrogen
peroxide, while Solution B contained 6% w/w of glyceryl triacetate
(FCC grade, Spectrum Chemnical, Gardena, Calif.). Initial color
readings were recorded for each bovine enamel sample and the
samples were marked either "A" or "B". The samples were immersed in
their corresponding solutions and allowed to whiten for periods of
30 minutes. After each 30-minute period, the samples were removed
and placed in distilled water for 60 seconds. The samples were then
removed, dried, and color readings were taken. Four treatments were
performed on one day, followed by a distilled water storage
overnight, after which another four treatments were performed,
utilizing fresh solutions. Following the eight treatments, the
samples were placed in yet another fresh solution and allowed to
remain immersed for another 24 hours to achieve their maximum
attainable whiteness. The results of the eight 30 minute
treatments, along with the data for both the distilled water
overnight storage period and the 24 hour immersion, are shown in
Table 1 below.
1TABLE 1 Total Treatment Sample A Sample B Sample A Sample B Time
(minutes) L.sub.A a.sub.A b.sub.A L.sub.B a.sub.B b.sub.B
.DELTA.E.sub.A .DELTA.E.sub.B 0 48.57 3.57 13.31 46.01 4.26 14.80
-- -- 30 54.79 2.38 14.21 58.17 2.14 15.88 6.40 12.39 60 58.22 2.00
14.94 61.05 1.69 15.98 9.91 15.30 90 60.39 1.63 14.79 65.53 0.55
13.38 12.09 19.92 120 63.57 1.08 13.76 68.51 0.11 10.68 15.21 23.25
Distilled water 12 hr 64.30 1.13 12.10 70.79 0.31 5.84 15.96 26.64
150 68.85 0.46 8.64 72.66 0.34 3.40 21.04 29.25 180 71.05 0.12 6.24
72.83 0.46 2.49 23.82 29.75 210 71.70 0.17 4.49 73.80 0.36 1.87
24.99 30.90 240 71.40 0.93 4.01 73.11 0.58 1.70 24.79 30.32 24
hours 78.06 0.17 0.54 77.53 0.29 0.60 32.32 35.30
[0059] It is clear from the comparative .DELTA.E values above that
the stained enamel specimen labeled as sample "B" experienced a
much more rapid whitening effect than sample "A", especially
following the first few 30-minute treatments. It should be noted
that sample B, after four treatments in Solution B containing 10%
hydrogen peroxide and 6% glyceryl triacetate, experienced a large
decrease in its b value (down to 5.84 from 10.68) during the 12
hour distilled water immersion between treatment days. Such an
effect was not observed for sample A which was immersed in the 10%
hydrogen peroxide solution alone.
[0060] Both specimens seemed to reach a higher degree of whiteness
after immersion in their respective solutions for 24 hours,
although Specimen B did achieve a .DELTA.E about 10 percent higher
than Specimen A.
[0061] A number of peroxyacid precursors were compared for their
ability to whiten extracted teeth by the method described above.
The following solutions were prepared by combining all of the
ingredients in separate 4-oz borosilicate glass bottles with
screw-on sealing caps.
2 Percent (w/w) Ingredient A B C D E Deionized water 50.0 49.5 49.5
49.5 49.5 Anhydrous ethanol 50.0 49.5 49.5 49.5 49.5 Glyceryl
triacetate 1.0 Acetylsalicylic acid 1.0 Tetraacetylethylenediamine
1.0 Polly(vinyl pyrollidone-co-vinyl 1.0 acetate) TOTAL 100.0 100.0
100.0 100.0 100.0
[0062] Each of the above solutions was brushed onto the crown
surface of an extracted human molar that had been previously graded
for tooth shade. All of the teeth had an initial VITA shade of A3
and after treating each tooth with solution, its roots were wrapped
with a moist paper towel in order to prevent any color change in
the tooth due to dessication. Each tooth crown was then coated with
the following gel composition.
3 Ingredient Percent (w/w) Distilled water 73.92
1-Hydroxyethylidene-1,1-diphosphonic acid 0.40 Sodium stannate 0.02
Carbopol 974P 5.00 Hydrogen Peroxide 35% 17.14 Ammonium hydroxide
(29%) 3.50 TOTAL 100.00
[0063] After 60 minutes, each tooth was graded for color and the
following results were recorded.
4 Initial Final Shade Pre-Treat Solution Shade Shade Change A A3 A2
4 B A3 B1 8 C A3 A2 4 D A3 A1 7 E A3 A2 4
[0064] As is evident from the data above, the composition
containing the peroxyacid precursor having three labile acetyl
functionalities and a low molecular weight, i.e. Sample B
containing glyceryl triacetate, generated the most whitening
capability. In contrast, the sample containing the high molecular
weight species tetraacetylethylenediamine delivered significantly
less whitening capability, while the samples containing the high
molecular weight species acetylsalicylic acid and poly(vinyl
pyrollidone-co-vinyl acetate) delivered dramatically less whitening
capability.
EXAMPLE II
[0065] Another test was done to determine the effect of pH on the
oral composition of the present invention at a given concentration
of hydrogen peroxide. Two solutions, C and D, were prepared from a
stock solution of 10% hydrogen peroxide. Solution C was adjusted to
a pH of 5.20 with 10% NaOH while solution D was adjusted to a pH of
7.80 with 10% NaOH. Just prior to immersion of the stained bovine
enamel specimens into solution, 6% w/w of glyceryl triacetate (FCC
grade, Spectrum Chemical, Gardena, Calif.) was added to each
solution. Initial color readings were recorded as above and the
samples were marked either "C" or "D". The samples were immersed in
their corresponding solutions and allowed to whiten for periods of
30 minutes. After each 30-minute period, the samples were removed
and placed in distilled water for 60 seconds. The samples were then
removed, dried, and color readings were taken as above. Three
treatments were performed in sequence. Following the three
treatments, the samples were placed in yet another fresh solution
and allowed to remain immersed for another 24 hours to achieve
their maximum attainable whiteness. The results of the eight 30
minute treatments, along with the data for both the distilled water
overnight storage period and the 24 hour immersion, are shown in
Table 2 below.
5TABLE 2 Total Treatment Sample C Sample D Sample C Sample D Time
(minutes) L.sub.C a.sub.C b.sub.C L.sub.D a.sub.D b.sub.D
.DELTA.E.sub.C .DELTA.E.sub.D 0 56.48 4.71 18.84 58.50 4.34 17.15
-- -- 30 63.83 3.48 21.11 79.09 0.78 17.32 7.78 20.90 60 71.45 2.11
21.11 83.50 -0.42 11.24 15.30 26.13 75.43 1.24 19.86 85.61 -0.31
7.11 19.29 29.28 90
[0066] It can be seen that sample D, which was soaked in solution D
at pH 7.8, performed substantially better than sample C, which was
soaked in solution C at pH 5.2.
EXAMPLE III
[0067] A commercially available product used in an office setting
by dentists utilizes 35% hydrogen peroxide and corresponds to a
composition described in U.S. Pat. No. 5,032,178. A mixture to be
applied to a stained tooth surface was prepared according to the
manufacturer's instructions and used to determine its ability to
remove tooth stain as above (a total of only two applications was
done). The results are shown in Table 3 below.
6TABLE 3 Total Treatment US 5,032,178 Sample D '178 Sample D Time
(minutes) L.sub.CP a.sub.CP b.sub.CP L.sub.D a.sub.D b.sub.D
.DELTA.E.sub.CP .DELTA.E.sub.D 0 60.00 3.30 15.45 58.50 4.34 17.15
-- -- 30 72.58 0.69 16.74 79.09 0.78 17.32 7.78 20.90 60 77.11
-0.05 14.86 83.50 -0.42 11.24 15.30 26.13
[0068] From Table 3, it can be seen that even though the commercial
product utilizes 30-35% hydrogen peroxide as an oxidizer, it did
not perform as well as solution "D", which contains only 10%
hydrogen peroxide and glyceryl triacetate, after two
treatments.
EXAMPLE IV
[0069] The following single-component composition was prepared and
is representative of a single-component embodiment of the
invention.
7 TABLE 4 Ingredient Percent (w/w) Polyethylene glycol 400 67.40
Sodium saccharin 0.50 Glyceryl triacetate 1.50 Polyvinylpyrrolidone
10.00 Fumed silica 12.00 Sodium percarbonate powder 8.00 Flavor
0.60 TOTAL 100.00
[0070] The above composition was manufactured under a vacuum of
26-26" Hg in a Ross double planetary mixer (Charles Ross & Son,
Hauppauge, N.Y.). All product contact parts in the mixer were
either KYNAR-coated metal or plastic in order to prevent leaching
of contaminant metals (such as iron, copper, and manganese) into
the composition during manufacture. KYNAR (a DuPont trademark) is a
fluoropolymer coating used to, among other purposes, prevent
corrosion of steel or metal parts in the presence of aggressive
chemicals. These same product contact parts were also passivated by
contacting them with a solution of 10 w/w percent hydrogen peroxide
and subsequently rinsed with distilled water just prior to use.
[0071] The above composition was prepared by placing the
polyethylene glycol into the mixing chamber, adding the sodium
saccharin and glyceryl triacetate, and allowing to mix under vacuum
at high speed until a clear solution was obtained. The
polyvinylpyrollidone was then added and mixed under vacuum at high
speed until homogeneously dispersed. The fumed silica was then
added, with slow mixing, to the above phase in the mixing chamber.
The addition of the fumed silica resulted in a high degree of
thickening of the total mixture. Finally, after the complete
homogenization of the above dispersion (the thickened carrier
matrix), the sodium percarbonate powder was added and dispersed
thoroughly, again under vacuum and high speed mixing. Finally, the
flavor was added and completely blended into the mixture, The
resulting bleaching composition was a slightly off-white gel. The
composition was transferred to polypropylene syringes for storage
and testing.
[0072] When water was mixed with the inventive composition (in a
ratio of approximately 1 part water to 5 parts gel, by weight), the
mixture quickly gave off an odor similar to acetic acid
(vinegar-type smell), which was indicative of peroxyacetic acid
generation. The composition was also placed on the surface of
several extracted human teeth, whereby a visible whitening effect
was seen after a 60 minute contact time.
EXAMPLE V
[0073] Another embodiment of the present invention, namely
dual-component compositions, were prepared in a similar fashion to
the manufacturing procedure outlined in Example IV, the only
exception being that each component of the dual-component
compositions in Table 5 below was prepared, packaged and stored
separately, to be combined just prior to application to the tooth
surface.
8TABLE 5 Percent (w/w) A B B C Ingredient 1 2 1 2 1 2 Propylene
42.56 45.00 glycol Polyethylene 70.00 73.40 glycol 400 Polyethylene
23.00 33.90 glycol 600 Glycerin 5.00 5.00 5.00 5.00 Distilled water
2.67 69.24 82.80 Sodium 0.80 0.80 saccharin Potassium 1.00
acesulfame Dequest 2010 0.10 0.40 Sodium 0.02 stannate Flavor 0.80
1.00 1.20 Carbopol 974P 2.00 2.00 5.00 5.00 Hydroxy- 10.00 10.00
propyl- cellulose Polyvinyl- 10.00 10.00 pyrollidone Fumed silica
12.00 12.00 Poly(vinyl- 1.00 pyrollidone-co vinyl acetate) Sodium
2.67 hydroxide monohydrate Ammonium 3.20 3.20 hydroxide 29%
Carbamide 12.00 peroxide Sodium 8.00 percarbonate powder Hydrogen
17.14 peroxide 35% Glyceryl 2.50 2.00 1.60 triacetate TOTAL 100.00
100.00 100.00 100.00 100.00 100.00
[0074] After manufacture, each of the above compositions was placed
in a separate chamber of a dual-chamber syringe, the type having a
plunger mechanism whereby externally applied pressure to the
plunger forces each of the two components through a mixing chamber
(known in the art as a static mixer) attached to the end of the
dual-chambered syringe. A further description of this method of
combining and mixing two incompatible components for the purpose of
bleaching teeth can be found in the copending U.S. patent
application Ser. No. 09/054,156 filed Apr. 2, 1998 hereby
incorporated by reference in its entirety. Just prior to use, the
two separate components are forced by the externally applied
pressure into one end of the static mixer, travel through baffles
in the static mixer which force the two components to blend
together, and finally emerge from the opposite end of the static
mixer as a single, homogeneous mixture. The resulting mixture thus
contains both the hydrogen peroxide precursor and glyceryl
triacetate, and alternatively, water in a sufficient amount to
allow the production of peroxyacetic acid for whitening the
teeth.
[0075] In order to demonstrate the superior tooth whitening
capabilities of the inventive compositions, tests on extracted
human teeth were performed, whereby measurements of changes in
qualitative color (VITA Shade Guide measurements, a method well
known in the art) were taken.
[0076] When mixed at a 1 to 1 weight ratio as described above
(forced under pressure through a static mixer syringe tip), all of
the above compositions generated peroxyacetic acid. A small amount
of each mixed composition was placed on the surface of an extracted
human molar which had been graded as to VITA shade color prior to
treatment. After a period of approximately 60 minutes, a visible
color change was observed on each of the molars.
EXAMPLE VI
[0077] A further embodiment of the present invention provides for
the combination of a hydrogen peroxide precursor and glyceryl
triacetate in situ. In this mode of applying the inventive
compositions, a first composition containing one of either the
hydrogen peroxide element or the glyceryl triacetate element is
placed directly onto the tooth surface to be whitened. A period of
time may be allowed for the first element to penetrate into the
tooth structure. Then, a second composition containing the
remaining inventive composition element is placed directly onto the
same tooth surface that has already been contacted with the first
composition. In this manner, both the hydrogen peroxide precursor
element and the glyceryl triacetate element are present on the
stained tooth surface simultaneously. Peroxyacetic acid is thereby
generated on and within the stained tooth providing a method of
applying the inventive compositions (and whitening teeth in
general) having certain advantages over other approaches.
[0078] Since peroxyacids (and peroxides in general) are highly
reactive species, an in situ method of applying and subsequently
generating oxidizing agents on and within a stained tooth surface
is advantageous. By generating the peroxyacid (in this invention,
peroxyacetic acid) on and within the tooth (thus in intimate
contact with the stain-causing molecules themselves), superior
tooth whitening results may be obtained. Although not wishing to be
bound by any particular theory, it is believed that deeper
penetration into the tooth structure by a first element (one of
either a hydrogen peroxide precursor composition or a glyceryl
triacetate composition) prior to contact with the second element
will generate peroxyacetic acid (upon placement of the second
remaining element) at the same site reached by the first element.
In this manner, the depth at which tooth whitening occurs by the
inventive compositions may be controlled. The in situ method
described above has an additional advantage, in that the amount of
peroxyacetic acid can be limited to that amount formed within the
tooth structure itself (i.e. only where both of the required
elements are present simultaneously). Accordingly, one aspect of
the present invention involves the application of a composition or
component of the composition onto the tooth surface and then
allowing the composition or a first component of the composition to
penetrate within the tooth structure itself Peroxyacid is then
allowed to generate within the tooth structure by application of an
aqueous solution or a second component capable of reacting with the
first component to generate a peroxyacid.
[0079] This in situ tooth whitening method may also be used with
other peroxyacid precursors other than, and/or in addition to,
glyceryl triacetate. Such peroxyacid precursors include all
water-soluble or partially water-soluble compounds containing at
least one acetyl group functionality, including, but not limited to
acetylated amino acids (such as acetyl cysteine, acetyl glycine,
etc) and acetylated polymers. Due to the desired penetration into
the tooth structure in order to reach deeper stains, low molecular
weight (<1000) acetyl group-containing molecules are
preferred.
EXAMPLE VII
[0080] A single-component toothpaste containing a very low level of
water was prepared that contained glyceryl triacetate, together
with sodium percarbonate as a hydrogen peroxide precursor.
9 Ingredient Percent (w/w) Polyethylene glycol 400 34.76
Polyethylene glycol 3350 1.00 Water 1.80 Glyceryl triacetate 2.00
Sodium percarbonate 5.00 Sodium bicarbonate 50.00 Hydrated silica
1.60 Sodium lauryl sulfate 0.60 Sodium methyl cocoyl taurate 0.60
Sodium fluoride 0.24 Sodium saccharin 1.20 Flavor 1.20 TOTAL
100.00
[0081] The above composition was manufactured in a manner similar
to that described in the Examples above and packaged in plastic
tubes. Upon extruding a small amount of the toothpaste and
combining it with water at a ratio of 1 part by weight toothpaste
to 1 part by weight water, an immediate odor of peroxyacetic acid
was evident.
EXAMPLE VIII
[0082] Chewing gum containing a thin slurry coating of sodium
percarbonate and glyceryl triacetate in vegetable oil was prepared.
A slurry of sodium percarbonate was first made by manually stirring
approximately 2.0 percent by weight of sodium percarbonate powder
(Solvay FB100) into a mixture of 20 parts highly refined avocado
oil (Super Refined Avocado Oil, Croda, Inc) and 1 part glyceryl
triacetate (by volume). A portion of the resulting slurry
(approximately 0.30 grams) was brushed onto the surface of a stick
of a commercially available chewing gum (Extra, Wm. Wrigley &
Son, Chicago, Ill.) and allowed to absorb overnight.
[0083] When manually kneaded in the presence of surface moisture
provided by dabbing the gum bolus onto a wet surface, a slight odor
of peroxyacetic acid was detected after about 30 seconds. It is
expected that a similar result would be obtained upon chewing a
stick of gum similarly prepared, thus providing peroxyacetic acid
to the oral cavity, including the surface of the teeth.
[0084] It is anticipated that other modes of applying, blending,
combining, and otherwise mixing together the components of chewing
gum with the inventive components, namely a hydrogen peroxide
precursor and glyceryl triacetate will result in a solid, chewable
object capable of generating peroxyacetic acid upon contact with
moisture from saliva.
[0085] It is to be understood that the embodiments of the present
invention which have been described are merely illustrative of some
of the applications of the principles of the present invention.
Numerous modifications may be made by those skilled in the art
based upon the teachings presented herein without departing from
the true spirit and scope of the invention.
* * * * *