Tooth whitening compositions

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.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 Embodiments of the present invention relate in general to oral
 compositions, and more particularly, to tooth whitening compositions.
 2. Description of Related Art
 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, predominatly 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.
 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.
 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.
 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.
 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.
 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).
 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.
 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 compound, 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).
 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.
 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
 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.
 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.
 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.
 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.
 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.
 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.
 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
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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. 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 The formation of peroxyacetic acid from hydrogen peroxide and glyceryl
 triacetate has been determined to occur roost 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.
 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.) 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.), which form in the presence of metal ions and their oxides.
 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 cheating 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.
 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.
 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.
 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.

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
 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.
 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.
 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.
 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.
 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.3.6H.sub.2 O, 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.
 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.
 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.
 The difference between the pretreatment (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.
 The overall change in color of stained pellicle was calculated using the
 CIELAB equation
EQU .DELTA.E=[(.DELTA.L*).sup.2 +(.DELTA.a*).sup.2 +(.DELTA.b*).sup.2 ]1/2
 The individual components of the L*a*b* scale were also analyzed separately
 to determine the specific changes in lightness, redness, and yellowness,
 respectively.
 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 Chemical, 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.
 TABLE 1
 Total Treatment
 Time Sample A Sample B Sample A Sample B
 (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
 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.
 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.
 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.

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- 1.0
 co-vinyl acetate)
 TOTAL 100.0 100.0 100.0 100.0 100.0
 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.

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
 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
 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% NaOK,
 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.
 TABLE 2
 Total Treatment
 Time Sample C Sample D Sample C Sample D
 (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
 90 75.43 1.24 19.86 85.61 -0.31 7.11 19.29 29.28
 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
 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.
 TABLE 3
 Total Treatment U.S. Pat. No.
 Time 5,032,178 Sample D '178 Sample D
 (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
 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
 The following single-component composition was prepared and is
 representative of a single-component embodiment of the invention.
 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
 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 mital 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.
 The above composition vas 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.
 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
 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.
 TABLE 5
 Percent (w/w)
 A
 B B C
 Ingredient 1 2 1 2 1 2
 Propylene glycol 42.56 45.00
 Polyethylene glycol 400 70.00
 73.40
 Polyethylene glycol 600 23.00 33.90
 Glycerin 5.00 5.00 5.00 5.00
 Distilled water 2.67 69.24 82.80
 Sodium saccharin 0.80 0.80
 Potassium acesulfame 1.00
 Dequest 2010 0.10 0.40
 Sodium stannate 0.02
 Flavor 0.80 1.00 1.20
 Carbopol 974P 2.00 2.00 5.00 5.00
 Hydroxypropylcellulose 10.00 10.00
 Polyvinylpyrollidone 10.00
 10.00
 Fumed silica 12.00
 12.00
 Poly(vinylpyrollidone-co vinyl acetate)
 1.00
 Sodium hydroxide monohydrate 2.67
 Ammonium hydroxide 29% 3.20 3.20
 Carbamide peroxide 12.00
 Sodium percarbonate powder 8.00
 Hydrogen peroxide 35% 17.14
 Glyceryl triacetate 2.50 2.00 1.60
 TOTAL 100.00 100.00 100.00 100.00 100.00
 100.00
 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 etch 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.
 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.
 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
 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.
 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.
 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
 (&lt;1000) acetyl group-containing molecules are preferred.
 EXAMPLE VII
 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.

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
 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
 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 FB 100) 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.
 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.
 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.
 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.