MXPA01008548A - Zinc containing dentifrice compositions - Google Patents

Abstract

A zinc containing low pH dentifrice composition provides better bioavailability of the zinc by incorporating a buffer system.

Description

DENTÍFRICAS COMPOSITIONS CONTAINING ZINC BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to anti-calculus dentifrice compositions containing zinc. Specifically, the invention is directed to low pH dentifrice compositions employing one or more slightly soluble zinc compounds as the active agent. Even more specifically, the dentifrice compositions according to the present invention significantly improve the bioavailability of zinc.

PREVIOUS ART Zinc compositions have been added to the dentifrice compositions to control the stones. See for example, the Patent of E.U.A. No. 4,100,269 of Pader.

The patent application under PCT WO 96/03109 by Warner Lambert describes an anticaries, antiseptic dentifrice; which have a pH of from about 3.0 to about 5.5. Acidifiers, including phosphoric acid, acid salts of phosphate, benzoic acid and food grade acids, such as citric acid; acidify the toothpaste. The dentifrice can also be stabilized with acid salts such as citric acid-sodium citrate, phosphoric acid-sodium phosphate, monobasic sodium phosphate-dibasic sodium phosphate, acetic acid-sodium acetate and benzoic acid and benzoate.

The patents of E.U.A. Nos. 4,545,979 and 4,550,018 of Ambike et al. Describe a composition for dental hygiene within a range of acidic pH from 3.0 to 5.0, pH regulators, fluoride, thymol, eucalyptol, methyl salicylate, flavorings in peppermint and peppermint oil and 0.1 to 2.0 weight percent, of one or more highly pure dodecyl sulfate alkali metal salts, with less than 5% alkyl sulfate salts without dodecyl.

Canadian Patent Application No. 834131 to Tisserand discloses a toothpaste preparation having an acidic pH of from about 3.8 to 5.8, optimally a pH of 4.0 to 5.5 and more preferably a pH of 4.0 to 4.8, fluoride and flavoring oils such as menthol , methyl salicylate or thyme oil and other flavorings, so that the composition is substantially free of hydrocarbon terpenes. According to Tisserand, when essential oils are used that are not free of terpenes in a fluorinated toothpaste having a pH in the range of about 3.8 to 5.8; the flavor develops a pronounced rancid and bitter hue in a period of less than 3 months.

While the prior art discloses a low pH toothpaste and other dentifrice compositions containing zinc, there is a need for dentifrice compositions that improve the release of bioavailable zinc, so that the effective zinc content can be decreased. It is believed that zinc compounds tend to be astringent. Therefore, the reduction of the zinc content in the product, can improve the acceptance of the product by the consumer.

SUMMARY OF THE INVENTION The present invention is directed to dentifrice compositions that include one or more slightly soluble zinc compounds. The term "slightly soluble" means that the zinc compound is not more than 5% w / w soluble in water. The dentifrice compositions according to the present invention also include a regulatory system and an oral carrier, wherein the dentifrice composition has a pH from about 3.0 to about 5.5, the zinc compound is in an amount sufficient to provide at least about 2000 ppm. of the zinc ion and the amount of the zinc ion that is bioavailable is at least about 1000 ppm.

The dentifrice compositions according to the present invention contain zinc ions and a regulating agent that produces a significant and unexpectedly improved bioavailability of zinc.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The dentifrice compositions according to the present invention include a source of zinc. It is known that zinc helps prevent tartar in the oral cavity. The zinc compounds that can be used in the present invention include: Zinc Bacitracin Zinc Oxide Zinc Citrate Zinc Peroxide Zinc Tribromosalicylanilide Zinc Phosphate Zinc Carbonate Zinc Pyrophosphate Zinc Fluoride Zinc Silicate Zinc Format Zinc Stearate Zinc Lactate Zinc Thanate Zinc Oleate Zinc Oxalate Chloride zinc Preferred salts are zinc citrate, zinc oxide, zinc pyrophosphate and zinc silicate. The most preferred salt is zinc citrate.

The zinc salt is added to the composition in an amount sufficient to provide zinc ions in an amount from about 0.01 to about 1.0% w / w of the composition. Preferably, the amount of zinc salt added to the composition is sufficient to provide zinc ions in an amount from about 0.02 to about 0.7% w / w of the composition. More preferably, the amount of zinc salt added to the composition is sufficient to provide zinc ions in an amount from about 0.05 to about 0.5% w / w of the composition. Even more preferably, the amount of the zinc salt added to the composition is sufficient to provide zinc ions in an amount from about 0.1 to about 0.3% w / w of the composition.

The amount of the zinc salt added to the compositions should be sufficient to provide the amounts of zinc ion, listed above. The exact amount of the zinc salt used can be easily determined by one skilled in the art and depends on the salt used.

The pH of the preferred embodiment according to the present invention is from about 3.0 to about 5.5. It has been found that a pH higher than 5.5 decreases the antiseptic activity of the dentifrice composition.

The pH of the claimed dentifrice is adjusted below 5.5 using suitable pharmaceutical grade or food acidifiers. These may include, but are not limited to, one or a combination of the following: phosphoric acid, benzoic acid, citric acid, or other tricarboxylic and smilar acids. More preferred acidifiers in the present invention include a phosphoric acid mixture from about 0.01% w / w to about 3.0% w / w, preferably within the range from about 0.1% w / w to about 1.5% w / w and more preferably within the range from about 0.2% w / w to about? .75% w / w, monobasic sodium phosphate from about 0.01% w / w to about 1% w / w, preferably from about 0.1% w / w to about 0.5 % weight / weight and more preferably from about 0.2% weight / weight to about 0.4% weight / weight, sodium dibasic phosphate from about 0.001% w / w to about 1.0% w / w, preferably from about 0.01% w / w to about 0.5% weight / weight and more preferably from about 0.01% weight / weight to about 0.05% weight / weight and acid benzoic within the range from about 0.01% w / w to about 1.0% w / w, preferably from about 0.05% w / w to about 0.5% w / w and more preferably from about 0.08% w / w to about 0.35% w / w weight. The exact amount of the added acidifier will depend on the final pH and the desired buffer capacity.

The pH of the products can be regulated with the salts of the acids in question.

Common regulatory systems include the salts of phosphoric acid and sodium phosphate, or citric acid and sodium citrate. Regulators suitable for use in the present invention include citric acid-sodium citrate, phosphoric acid-sodium phosphate, monobasic sodium phosphate, dibasic sodium phosphate, acetic acid-sodium acetate, sodium succinic acid-succinate, aconitic acid sodium and benzoic acid benzoate sodium conitate in amounts of up to about 1% w / w, preferably from about 0.05% w / w to about 0.75% w / w of the composition and more preferably from about 0.1% w / w up to about 0.5% w / w of the composition.

The dentifrice compositions according to the present invention contain anti-microbial agents and one or more fluoride release compounds that provide anti-caries activity. The dentifrice compositions of this invention also contain, but are not limited to, one or more of the following dentifrice additives: abrasives, surfactants, binders and thickeners, humectants, sweeteners, degreasing agents, flavors, colors and preservatives. The above additives and active ingredients are combined in a hydrated or anhydrous vehicle to form a solid (for example, tooth powder), a semi-solid (for example, paste or gel), or a liquid.

The present invention may also include an anti-microbial agent. One class of anti-microbial agent known to be used in dentifrices is the non-cationic anti-microbial agent. An anti-microbial agent substantially insoluble in water has a solubility in water at 25 ° C, of less than 1%, preferably less than 0.5% and more preferably less than 0.1%. The anti-microbial agents employed in the dentifrice compositions of this invention can be considered to be essentially non-ionic in nature. However, many suitable anti-microbial compounds contain one or more hydroxyphenolic groups that can be ionizable at certain pHs. A more accurate description of the general class of suitable anti-microbial agents useful in the dentifrice composition of this invention is that they are, by nature, non-cationic.

Examples of classes of non-cationic anti-microbial agents that can be employed in the dentifrice composition of the invention are the phenolic and bisphenolic compounds, halogenated diphenyl ethers, benzoate esters and carbanilides.

Illustrative phenolic anti-microbial compounds, which include the halogenated salicylanilides are, 2-phenylphenol, 4-chlorophenol, 4-chloro-2-methylphenol, 4-chloro-3-methylphenol, 4-chloro-3,5-dimethylphenol, 2 , 4-dichloro-3,5-dimethylphenol, 3,4,5,6-tetrabromo-2-methylphenol, 5-methyl-2-pentylphenol, 4-isopropyl-3-methylphenol, 5-chloro-2-hydroxydiphenylmethane, 4 '5-dibromosalicylanilide, 3,4', 5-trichlorosalicylanilide, 3,4'5-tribromosalicylanilide, 2,3,3'5-tetrachlorosalicylanilide, 3,3'4,5'-tetrachlorosalicylanilide, 3,5-dibromo-3 '-trifloromethylsalicylanilide, 5-n-octanoyl-3'-trifluoromethylsalicylanilide.

The bisphenol compounds include 2,2'-methylenebis (3,4,6-trichlorophenol), 2,2'-methylenebis (4-chlorophenol), 2,2'-methylenebis (4-chloro-6-trichlorophenol). , 2,2'-methylenebis (4-chlorophenol), 2,2'-methylenebis (4-chloro-6-bromophenol), bis (2-hydroxy-3,5-dichlorophenyl) sulfide, bis (2-hydroxy-5) -chlorophenyl) sulfide.

Said antibacterial agents can be employed in the form of their zinc derivatives, many of which are described in the U.S.A. No. 4,022,880.

Exemplifying the class of the halogenated hydroxyphenyl ethers are the compounds 2 ', 4,4'-trichloro-2-hydroxy-diphenyl ether and 2,2'-dihydroxy-5,5'-dibromo-diphenyl ether.

Another well-known class of non-cationic anti-microbial agents are the esters of p-hydroxybenzoic acid, especially the esters of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, heptyl and benzyl.

The halogenated carbanilides, whose class is typified by 3,4,4'-trichlorocarbanilide, 3-trifluoromethyl-4,4'-dichlorocarbanilide, 3,3 ', 4-trichlorocarbanilide, can also be used.

Other known non-cationic anti-microbial agents substantially insoluble in water can also be used, for example the alcohol 2,4-dichlorobenzyl, 3,4-dichlorobenzyl alcohol and 3- (4-chlorophenoxy) -propan-1,2-diol.

The aforementioned anti-microbial agents which are suitable for use in dentifrices are non-antibiotics. Antibiotics are generally not used because they eliminate the risk of resistance to foreign elements that bacteria develop. Usually, the anti-microbial agent will be used in an amount of 0.01 to 5%, preferably 0.05 to 1% by weight of the dentifrice. Of course, a mixture of anti-microbial agents can be used.

The dentifrice compositions according to the present invention may also include essential oils. Essential oils are volatile aromatic oils that are synthetic or derived from plants by distillation, expression or extraction. In general, essential oils carry the smell or flavor of the plant from which they are obtained. If they are used in the dentifrice composition of the present invention, they provide an anti-gingivitis activity. Some of said essential oils may also act as flavoring agents. The essential oils of this invention include, but are not limited to, thymol, menthol, methyl salicylate (wintergreen oil) and eucalyptol. Thymol, also known by the chemical formula 5-methyl-2- (1-methylethyl) phenol, is obtained from the essential oil of Thymus vulgaris Labiatae and Monarda punctata Labiatae. Thymol is a white crystalline powder with an aromatic smell and flavor. Thymol is soluble in organic solvents, but only slightly soluble in deionized water.

Menthol is isolated mainly from Mentha arvensis oil. In its commercial form, menthol is available as L-menthol crystals obtained from a process that involves the cooling of the oil. Fractional distillation of peppermint oil, which usually contains from about 40% to about 65% menthol, represents another important source of menthol. Synthetic sources of L-menthol are also available.

Eucalyptol is derived from the eucalyptus tree. Since it has a refreshing smell and taste, this essential oil is often combined with other essential oils, such as menthol, for the preparation of formulations in which it imparts a medicinal effect. Menthol and eucalyptol combinations are widely used. Particularly preferred uses of the menthol-eucalyptol combination include, according to the present invention, toothpastes such as toothpastes or dental gels.

Methyl salicylate is the main ingredient in many essential oils, constituting approximately 99% of wintergreen oil (Gaultheria procumbens) and sweet birch oil (Betula lento). Methyl salicylate, which has a distinctive refreshing aroma, is widely used in mouth rinses, chewing gums and other oral and pharmaceutical preparations.

The amounts of essential oils that can be used in the dentifrice compositions of the present invention are from about 0.46% to about 0.5623% thymol, about 0.4644% up to about 0.5676% methyl salicylate, about 0.306% up to about 0.374% menthol and approximately 0.6971% up to approximately 0.8519% eucalyptol, which is clinically effective to inhibit gingivitis. More preferably, a dentifrice in accordance with the present invention contains about 0.5112% thymol, about 0.5160% methyl salicylate, about 0.34% menthol and about 0.7745% eucalyptol and is clinically effective in inhibiting gingivitis.

Floser release compounds can be used in the dentifrice compositions of the present invention. Said compounds can be totally or slightly soluble in water, release fluorine ions or ions containing fluorine in water and do not react with the other components of the composition. It is well known that tooth compositions containing fluorine-releasing compounds help prevent tooth decay. Typical compounds that release fluorine are the inorganic salts of fluorine, such as the salts of alkaline torric metals soluble in water, alkali metal salts and heavy metal salts. Sodium monofluorophosphate, sodium fluoride, stannous fluoride and mixtures of said compositions are preferred.

The amount of the fluorine releasing compound present in the dentifrice compositions of the present invention must be non-toxic. The specific amount depends on the type of compound that releases fluoride used, the solubility of the fluorine releasing compound and the formulation of the dentifrice composition. In general, the fluorine releasing compound will be present in a weight amount of up to about 1.2% w / w, preferably from about 0.1% w / w to about 1.0% w / w and more preferably from about 0.175% w / w to about 0.8% w / w of the tooth composition, so provide 800-1500 ppm F ".

Surfactants or active surface agents are organic compounds that reduce the surface tension between liquids and aid dispersion of a composition along the oral cavity. The surfactant in the present invention can be anionic, nonionic, or amphoteric.

The oral hygiene or dentifrice compositions of the present invention may contain surfactants in amounts of up to 5.0% w / w, preferably from about 0.1% w / w to about 3.0% w / w of the dentifrice composition and more preferably from about 0.2. % weight / weight up to about 2.0% weight / weight of the tooth composition.

The most preferred surfactants are anionic. Such anionic surfactants include, but are not limited to, sodium lauryl sulfate, sodium lauryl sarcosinate, sodium cocoyl methyl taurate and disodium lauryl sulfosuccinate. A preferred surfactant is sodium lauryl sulfate. The compositions according to the present invention are substantially free of one or more highly pure salts of alkaline metals of dodecyl sulfate, having less than 5% alkyl sulfate salts without dodecyl.

Amphoteric surfactants have the ability to behave like an acid or a base and include quaternary imidazole derivatives. Preferred amphoteric surfactants include derivatives of the long chain amino alkylamino (alkyl) alkylated amines, also known as MIRANOL®, manufactured by Rhone-Poulanc, Cranberry, New Jersey.

Natural and artificial sweetening dentifrices can be used in the tooth compositions. The sweetener may be selected from a wide variety of well-known materials including naturally occurring water soluble sweeteners, water soluble artificial sweeteners and water soluble modified sweeteners derived from water-soluble sweeteners of natural occurrence. Artificial water-soluble sweeteners include, but are not limited to, soluble salts of saccharin, for example sodium or calcium saccharin salts, cyclamate salts, sodium, the ammonium or calcium salt of 3,4-dihydro-6 -methyl-1, 2,3-oxathiazine-4-one-2,2-dioxide, the potassium salt of 3,4-dihydro-6-methyl-1,2,3-oxathiazine-4-one-2,2 -dioxide (Acesulfame-K) the free acid form of saccharin and the sweeteners based on dipeptides, such as the sweeteners derived from L-aspartic acid. The dipeptide-based sweeteners include L-aspartyl-L-phenylalanine methyl ester (Aspartame) and the materials described in the U.S. patent. No. 3,492,131, L-alpha-aspartyl-N- (2,2,4,4-tetramethyl-3-thietanyl) -D-alaninamide hydrate (Alitame), methyl esters of L-aspartyl-L-phenyl glycerin and L-aspartyl-L-2,5-dihydrophenylglycine, L-aspartyl-2,5-dihydro-L-phenylalanine and L-aspartyl-L- (1-cyclohexene) -alanine. Water-soluble sweeteners of natural occurrence include, but are not limited to, sugar alcohols including sorbitol as a solution of 70% sorbitol, mannitol, xylitol, maltitol, hydrogenated starch hydrolyzates, and mixtures thereof.

Water-soluble sweeteners derived from water-soluble sweeteners of natural occurrence include, but are not limited to, chlorinated derivatives of sucrose, known for example, under the brand name Sucralose and protein-based sweeteners such as thaumaoccous danielli (Thaumatin I and II).

The sorbitol solution provides sweetness and body to the composition and gives a pleasant sensation in the mouth. The sorbitol solution also improves the taste, prevents margo flavor and provides a feeling of freshness and cleanliness in the mouth. It also prevents the cracking of the toothpaste.

In general, an effective amount of sweetener is used to provide the desired level of sweetness in any particular embodiment of the dentifrice compositions in accordance with the present invention. Said amount will vary according to the selected sweetener and the final form of the composition. The amount of sweetener normally present is from about 0.0025% w / w to about 60% w / w of the dentifrice composition. The exact range of the amounts for each type of sweetener in a toothpaste is quickly determined by those skilled in the art.

Flavors that can be used in the invention include natural and artificial flavors known in the toothpaste art. Suitable flavors include, but are not limited to, mints, such as mint, citrus flavors such as orange and lemon, artificial vanilla, cinnamon, various fruit flavors and the like. Anethole (or anisol camphor, p-propenyl-anisole) is a constituent flavor of anise and fennel oils, which are widely used as a flavoring and antiseptic agent and have been found to be useful in masking the bitter taste of thymol.

The amount of flavor is normally a matter of preference subject to the type of final composition of the dentifrice, the individual flavor employed and the desired intensity of taste. Preferably, the flavors are used in amounts which may be from about 0.01% w / w to about 6% w / w of the dentifrice composition. The flavors used in the compositions according to the present invention comprise flavor oils that are not substantially free of terpenes.

The coloring agents are used in effective amounts to produce a dentifrice of the desired color. Said coloring agents can be incorporated in amounts of up to about 3% by weight of the dentifrice composition. Coloring agents can also include natural food colors and inks suitable for food and cosmetic applications and medicines. Such coloring agents are known as inks and lacquers FD & C. The coloring materials are preferably soluble in water. Illustrative examples include, without being limited to, the digoid dye known as Blue FD & C No. 1 and Yellow FD & C No. 10. A complete list of all FD & C and its corresponding chemical structures can be found in the Kirk-Othmer Encyclopedia of Chemical Technology, 3rd. Edition, Volume 5 on pages 857-884. A preferred opacifier, titanium dioxide, may be incorporated in amounts of up to 2.0% w / w, preferably less than about 1% w / w of the composition, and more preferably less than about 0.4% w / w.

Suitable humectants in this invention include sorbitol, as a solution of 70% sorbitol, glycerin, propylene glycol, polyethylene glycol, mixtures thereof and the like. The humectants may be present in amounts of from about 1% to about 75.0% by weight of the dentifrice composition.

The abrasive substances suitable for use in this invention should be compatible with the low pH of the composition and include hydrated silica, allyme or alkali metal metaphosphates. The silica abrasives in the dentifrice composition according to this invention may include among others the ZEODENT® (113), manufactured by J.M. Hubert Corp., and SYLOID® or SYLODENT®, manufactured by W.R. Grace Co., said polishing agents can be used in amounts of about 75.0% w / w of the composition, preferably in amounts up to about 5.0% w / w to about 40% w / w of the composition and more preferably from about 5.0% weight / weight up to about 30.0% weight / weight of the composition.

The tooth composition includes an oral vehicle which can be a paste, gel, powder or liquid. Depending on the specific form of the dentifrice, the composition may also include binding or gelling agents to provide the desired consistency. They can be used alone or in combination, gelling agents such as hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, xanthan gum, gelling silicas and the like. The preferred gelling system is a mixture of carboxymethyl cellulose, xanthan gum and gelling silica. The gelling agents can be used in amounts from about 0.5% w / w to about 30% w / w, preferably from about 5.0% w / w to about . 0% w / w of the dentifrice composition and more preferably from about 7.0% w / w to about 20% w / w of the composition.

The dentifrice composition of this invention may also contain a degreasing agent such as strontium chloride, potassium nitrate or sodium citrate-citric acid, which may be used in an amount from about 0.5% w / w to about 10% w / w. .

Suitable preservatives include benzoic acid, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), ascorbic acid, methyl paraben, propyl paraben, tocopherols and mixtures thereof. When these condoms are used, they are generally present in amounts of up to about 1.0% w / w and preferably from about 0.1% w / w to about 1.0% w / w of the dental gel composition.

The present invention is further illustrated by the following non-limiting examples. All parts and percentages in the examples and throughout the description and claims are given by weight of the final composition, unless otherwise specified.

Examples 1-2 and Comparative Example 1 The dentifrice compositions were formulated with the ingredients listed in Table 1.

Table 1 Bio-availability studies The bioavailability of zinc in the compositions according to the present invention was measured using the following method. Bioavailability is the amount of zinc present in a toothpaste after 60 seconds of mixing. This approximates the time when the average person applies a tooth composition to the teeth by brushing.

Test Runoff For each toothpaste, a 1: 3 dentifrice-water run was made by adding 12 g of twice deionized water to 4 g of toothpaste in a 30 ml flat bottom test tube and a 60 second dispersion by a device of agitation or mixed without air. The aliquots of the runoff were immediately placed in plastic Eppendorf microcentrifuge tubes and centrifuged at 12,000 rpm. The aliquots of the remnant were removed with a pipette without altering the lentil and the available zinc was immediately measured as described above.

Zinc analysis available A sample of each solution was diluted with the appropriate solution and the zinc content was determined by comparison with respect to a standard curve prepared in a similar manner. An Elmer AA 3030 spectrophotometer equipped with a hollow zinc cathode lamp was used to determine the zinc content in the solutions. The results are presented in Table 2. Table 2 As can be seen in the results listed in TABLE 2, Example 1 released approximately 30% more zinc than the comparative example, although it had the same amount of zinc. Additionally, Example 2, which had half the zinc as the comparative example, was able to release the same amount of zinc as the comparative example.

Both animal and clinical studies were conducted to determine the amount of stone reduction.

Rat calculations Studies in the rats were conducted by applying each composition on the teeth of the rats individually with a cotton swab, every morning and evening for 5 days in a week for a period of three weeks. The stone formation was recorded in accordance with the method of Francis and Briner, Journal of Dental Research, Vol. 48, 1185-1195 (1969). The results are presented in Table 3. The results of the study of the calculations in the rats indicated that the formulation of this invention (example 2) was effective in reducing stone formation, even when only 1% zinc citrate was present. .

Clinical Study of the Calculations in Humans The dentifrice compositions according to Examples 1 and 2 were tested for the inhibition of the stones in a clinical study. Said study consisted of the following stages: 1. - The participants underwent a deep dental cleaning to eliminate all tartar. 2. - The participants subsequently used a test placebo, Crest® Regular, for three months. 3.- The participants were evaluated and the results were recorded with respect to the level of tartar removed, then they were separated into a group 3 of balanced treatment. 4.- The participants underwent a second dental cleaning to remove all the tartar. 5.- Participants used 1% ZCT, 2% ZCT or placebo products for 3 months. 6.- The participants were evaluated and the results were recorded again regarding the level of tartar removed using the Volpe Manhold method.

The results are presented in Table 3. Clinical results indicate that the formulation of this invention (example 2) provides excellent inhibition of the stones, even when only present in the 1% zinc citrate formula.

Table 3 As can be seen in the results listed in TABLE 3, Example 2, which releases the same amount of bioavailable zinc as the comparative example, was able to achieve parity in the reduction of the calculations that the comparative example.

While the invention has been described in detail and with reference to specific examples thereof, it will be apparent to the person skilled in the art that various changes and modifications are possible without departing from the scope spirit of the invention.

Claims (6)

1. - A dentifrice composition comprising: a zinc compound, a regulatory system and an oral vehicle, wherein the dentifrice composition has a pH from about 3.0 to about 5.5, the zinc compound is in an amount sufficient to provide at least 2000 ppm of the zinc ion and the amount of the zinc ion that is bioavailable is at least 1000 ppm.

2. - The dentifrice composition according to claim 1, is where the pH is about 4.5

3. - The dentifrice composition according to claim 1, wherein the regulatory system comprises an acid and at least one corresponding salt.

4. - The tooth composition according to claim 3, wherein the acid and the corresponding salt are selected from the group consisting of citric acid-sodium citrate, phosphoric acid-sodium phosphate, sodium monobasic phosphate and sodium dibasic phosphate, acetic acid-sodium acetate, succinic succinate-sodium succinate, aconitic acid-sodium aconite and benzoic acid-sodium benzoate.

5. The dentifrice composition according to claim 1, wherein the zinc compound is selected from the group consisting of zinc citrate, zinc oxide, zinc pyrophosphate and zinc silicate.

6. - The dentifrice composition according to claim 5, wherein the zinc compound is zinc citrate.