Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q11/00—Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
  • A61K8/24—Phosphorous; Compounds thereof

Definitions

• This invention concerns inhibiting tooth enamel demineralization. More specifically it relates to the use of a water soluble phosphate, particularly a pyrophosphate or tripolyphosphate, to inhibit demineralization while not negatively impacting remineralization. This provides a means for preventing or reducing dental caries.
• Dentifrices, pastes and mouthwashes contain a low level of a fluoride salt, most often as the alkali metal fluorides, alkali metal salts of monofluorophosphate and stannous fluoride.
• a usual, and effective, fluoride concentration in these types of products is on the order of 1100 parts per million (ppm). To date no other chemical approach has been developed as a means for inhibiting enamel demineralization and thus preventing or treating dental caries.
• This invention has two aspects. One is a method for reducing or preventing dental caries in humans by inhibiting enamel demineralization, which method comprises treating the teeth with a formulation containing a demineralization inhibitor consisting essentially of an effective non-toxic amount of a water soluble pyrophosphate or tripolyphosphate in an orally acceptable carrier.
• this invention covers an orally acceptable formulation for preventing dental caries in humans by reducing or preventing demineralization which comprises an orally acceptable carrier and an inhibitor of enamel demineralization consisting essentially of an effective non-toxic amount of a water soluble pyrophosphate or tripolyphosphate.
• this invention utilizes certain phosphates as a means for inhibiting tooth enamel demineralization and thus reducing or preventing dental caries. It has been found that the presence of a orally acceptable water soluble phosphate is the critical factor, not the acid or salt form in which it is presented.
• a phosphate may be an orthophosphate, a pyrophosphate, a polyphosphate (chain phosphates) or a metaphosphate (cyclic phosphates).
• the preferred phosphates are pyrophosphate and tripolyposphate. So far as the ionic form of the phosphate is concerned, the acid form of each of these phosphates should not be used.
• acid phosphates such as H5P3O10 or H4P2O7 should not be used. But the partially neutralized forms may be used, though the fully neutralized forms are usually preferred.
• the salts of Group la alkali metals of periods 2, 3 and 4 are preferred, particularly the sodium and potassium forms and mixtures thereof. Most preferred is Na5P3 ⁇ o alone or mixtures of a4P ⁇ 7 and K4P2O7. Notwithstanding this preference, several phosphate types and ionic forms may be incorporated into a single preparation.
• the phosphate may be anhydrous or hydrated.
• phosphate preparations In particular sodium and potassium pyrophosphate and sodium tripolyphosphate are available from a number of companies. Or the salts may be custom prepared to define standards by a commercial source or by the one who is doing the formulation work by using published techniques and processes. Pure phosphate preparations meeting local regulatory requirements should be used in these dental preparations. Effective concentrations of phosphate will vary with the type of phosphate selected, its water solubility, the type of product (i.e., toothpastes, mouthwashes, chewing gums) and may be influenced by the nature and chemical or physical characteristics of the carrier and co- formulated excipients. Some ingredients or formulations may have a higher available phosphate content.
• an effective amount is that amount which will reduce enamel demineralization to an extent that dental caries will be reduced in a statistically significant manner over a phosphate-free control which is also free of any other demineralization inhibiting agent or remineralizmg agent.
• a phosphate ion should provide an effective anti-caries preparation when used incorporated into orally acceptable preparations and when used in a normal, routine fashion.
• a preferred baseline for toothpastes, gels and liquids is 5% by weight.
• sodium tripolyphosphate concentrations 5% w/w is a preferred amount.
• pyrophosphates a preferred amount is about 1.8% tetrasodium pryophosphate and 4.0% tetrapotassium pyrophosphate.
• Phosphates may represent a higher percentage of the overall ingredient profile in dry formulations such as dental tablets, lozenges and chewing gums.
• phosphates can be presented in any orally acceptable carrier.
• the only limitation is that the phosphate must be available to interact with tooth enamel and the formulation must not have any deleterious or untoward affects on the teeth or the oral cavity when used within approved guidelines.
• Toothpastes, gels and liquid formulations may be prepared with conventional ingredients, keeping in mind that certain abrasives may not be compatible with certain water soluble phosphates.
• a preferred toothpaste or gel will contain about 5% of the pyrophosphate salt or tripolyphosphate salt, about 10 to 80% of a humectant, about 0.25 to 5% of a detergent, up to 2% sweetening and flavoring agents (in combination), coloring agents, binders and thickening agents, and water in amounts sufficient to make a stable, flowable paste or- gel.
• the abrasive polishing material contemplated for use in the present invention can be any material which does not excessively abrade dentin.
• silicas including gels and precipitates, calcium pyrophosphate, calcium polymetaphosphate, insoluble sodium polymetaphosphate, hydrated alumina, and resinous abrasive materials such as particulate condensation products of urea and formaldehyde, and others such as disclosed by in U.S. Pat. No. 3,070,510 incorporated herein by reference. Mixtures of abrasives may also be used. Certain abrasives may not be compatible with the metioned phosphates.
• Silica dental abrasives of various types, can provide the unique benefits of exceptional dental cleaning and polishing performance without unduly abrading tooth enamel or dentin. Silica abrasive materials are also exceptionally compatible with many ionic materials including the phosphates which are the subject of this invention. For these reasons they are preferred for use herein.
• the silica abrasive polishing materials useful herein, as well as the other abrasives generally have an average particle size ranging between about 0.1 and 30 microns, preferably 5 and 15 microns.
• the silica abrasive can be precipitated silica or silica gels such as the silica, xerogels described in U.S. Pat. No. 3,538,230 and U.S. Pat. No.
• abrasive in the dentifrice compositions described herein is present at a level of from about 6% to about 70%, preferably from about 15% to about 25% when the dentifrice is a toothpaste. Higher levels, as high as 90%, may be used if the composition is a tooth powder.
• Flavoring agents can also be added to the dentifrice and other compositions of the present invention. Suitable flavoring agents include oil of wintergreen, oil of peppermint, oil of spearmint, oil of sassafras, and oil of clove. Sweetening agents are also useful and include aspartame, acesulfame, saccharin, dextrose, levulose and sodium cyclamate. Flavoring and sweetening agents are generally used in the compositions herein at levels of from about 0.005% to about 2% by weight.
• the dentifrice compositions of this invention may also contain emulsifying agents. Suitable emulsifying agents are those which are reasonably stable and foam throughout a wide pH range, including anionic, nonionic, cationic, zwitterionic and amphoteric organic synthetic detergents. Nonionic surfactants are preferred. Many of these suitable surfactants are disclosed in U.S. Pat. No. 4,051,234 incorporated herein by reference. Water is also present in the toothpaste compositions of this invention. Water employed in the preparation of commercially suitable compositions should preferably be deionized and free of organic impurities. Water generally comprises from about 10% to 70%, preferably from about 20% to 40%, by weight of a toothpaste. These amounts of water include the free water which is added plus that which is introduced with other materials such as when sorbitol or other polyhydric alcohols which are manufactured as dilutions where water is the diluent.
• Thickening agents generally are added to toothpastes and gels to provide a desirable consistency.
• Preferred thickening agents are carboxyvinyl polymers, carrageenan, hydroxyethyl cellulose and water soluble salts of cellulose ethers such as sodium carboxymethyl cellulose and sodium carboxymethyl hydroxyethyl cellulose.
• Natural gums such as gum karaya, gum Arabic, and gum tragacanth and polysaccharide gums such as xanthan gum can also be used.
• Colloidal magnesium aluminum silicate or finely divided silica can be used as part of the thickening agent to further improve texture.
• Hydroxyethyl cellulose is a preferred binder.
• Thickening agents in an amount from 0.5% to 5.0% by weight of the total composition maybe used.
• a humectant in a toothpaste to keep it from hardening.
• Suitable humectants include glycerin, sorbitol, and other edible polyhydric alcohols such as PEGs, at a level of from about 10% to about 70%.
• Antibacterial agents may be added to these pastes and gels (and mouthwashes). Any one of a number of antibacterial drugs or agents may be used. Triclosan, 5-chloro-2-(2,4-dichlorpphenoxy)phenol, is one example. A group of useful antibacterials is the cationic antibacterial agent. Suitable cationic antibacterial agents for use in dentifrices include:
• quaternary ammonium compounds for instance those in which one or two of the subsistent on the quaternary nitrogen has between 8 and 20, preferably 10 and 18 carbon atoms and is preferably an alkyl group, which may optionally be interrupted by an amine, ester, oxygen, sulphur, or heterocyclic ring.
• the remaining nitrogen substituents will have a lower number of carbon atoms, for instance between 1 and 7, and are preferably alkyl, for instance methyl or ethyl, or benzyl.
• the anion will be an orally acceptable salt forming group.
• Examples of such compounds include benzalkonium chloride, dodceyl trimethyl ammonium chloride, benzyl dimethyl stearyl ammonium chloride, cetyl trimethyl ammonium bromide, benzethonium chloride (diisobutyl phenoxyethoxyethyl dimethylbenzyl ammonium chloride), and methyl benzethoniu chloride; ⁇ ) pyridinium and isoquinolinium compounds, exemplified by hexadecylpyridinium chloride, cetyl pyridinium chloride, and alkyl isoquinolinium bromide;
• pyrimidine derivatives such as hexetidine (5-amino-l,3- Bi(2-ethylhexyl)-5-n ⁇ ethylhexahydropyrimidine);
• aniline derivatives such as hexamidine isothionate (4,4'- diamonding-a,w-diphenoxyhexane isothionate);
• biguanides including: (a) mono-biguanides such as p-chlorobenzyl biguanide and N- (4-chlorobenzyl)-N"-(2,4-dichlorobenzyl)biguanide.
• Ai and A2 are independently a phenyl group optionally substituted by (C ⁇ _4)alkyl, (C ⁇ _4)alkoxy, nitro, halogen, C- .i2)alkyl group, or (C4_i2)alicylclic;
• Xl and X2 are independently (C ⁇ .3)alkylene; R and R 1 are independently hydrogen, (C ⁇ _-L2)alkyl, or aryl(C- . 6)alkyl; 7_ ⁇ and Z2 are independently 0 or 1;
• Q is CH2, oxygen, sulfur, or aryl; n in each (CH2) n group is independently an integer from 1 to 12 but the total of both n groups may not exceed 12; aryl is phenyl, naphthyl or another aromatic ring; and orally acceptable acid addition salts thereof.
• Preferred compounds are chlorhexidine and alexidine.
• poly(biguanides) such as polyhexamethylene biguanide hydrochloride.
• An effective amount of a antibacterial agent is in the range of about 0.005 to 10% weight/weight (w/w), preferably 0.005 to 5%, more preferably 0.005 to 2.5% and most preferably 1.0% w/w.
• An optional ingredient which may be useful in any of the present compositions which contains a cationic antimicrobial agent is an anti- stain agent.
• Cationic antimicrobial materials may cause staining when used at fairly high levels.
• Anti-stain agents include carboxylic acids such as those disclosed in U.S. Pat. No. 4,256,731, incorporated herein by reference.
• Other agents include amino carboxylate compounds as disclosed in U.S. Pat. No. 3,937,807; dicarboxylic acid esters as disclosed in U.S. Pat. No. 4,080,441; and phosphonoacetic acid as disclosed in U.S. Pat. No. 4,118,474. All of these patents are also incorporated herein by reference.
• a toothpaste of the present invention may be prepared in a -uniform color or in the form of a striped toothpaste.
• a suitable apparatus for filling toothpaste tubes with striped toothpaste is described in U.K. Patent Specification No. 962,757.
• Mouthwashes generally comprise about 20:1 to about 2:1 of a water/ethyl alcohol solution and preferably other ingredients such as flavoring agents, sweeteners, humectants and surfactants.
• Suitable flavoring agents include oil of wintergreen, oil of peppermint, oil of spearmint, oil of sassafras, and oil of clove.
• Sweetening agents which can be used include aspartame, acesulfame, saccharin, dextrose, levulose and sodium cyclamate.
• Suitable humectants include sorbitol and glycerin while suitable surfactants include oleate and laurate esters of sorbitol and its anhydride condensed with ethylene oxide as well as ethylene oxide and propylene oxide condensates.
• suitable surfactants include oleate and laurate esters of sorbitol and its anhydride condensed with ethylene oxide as well as ethylene oxide and propylene oxide condensates.
• Another type of surfactant which may be used are the amphoterics.
• amphoteric sudsing agents useful in the present invention can be broadly described as derivatives of aliphatic secondary and tertiary amines in which the aliphatic radical can be straight chain or branched and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic water- solubilizing group, e.g., carboxylate, sulfonate, sulfate, phosphate, or phosphonate.
• anionic water- solubilizing group e.g., carboxylate, sulfonate, sulfate, phosphate, or phosphonate.
• the mouthwashes of the invention comprise 0.5% to 5% of the phosphate, 5% to 30% (preferably 5% to 20%) ethyl alcohol, 0% to 25% (preferably 3% to 20%) of a humectant, 0% to 25% (preferably 0.01% to 2.0%) surfactant, 0% to 5% (preferably 0.005% to 0.3%) sweetening agent, 0% to 0.3% (preferably 0.03% to 0.3%) flavoring agent, about 0.1% of a preservative, pH adjusting agent as needed, and the balance water.
• the pH of a mouthwash and/or its pH in the mouth can be any pH which is safe for the mouth's hard and soft tissues. Generally the pH will be adjusted to about 3 to about 10, preferably from about 4 to about 8.
• Products which employee these phosphates are to be used in a conventional manner.
• brushing the teeth with a toothpaste containing such a water soluble phosphate makes the phosphate available to the teeth and thus inhibits the formation of dental caries or reduces the development of dental caries in persons susceptible to the formation of dental caries.
• Mouthwashes are also used in the normal and accepted fashion to prevent caries in susceptible persons or to prevent further development of dental caries in susceptible persons Likewise dental powders, tablets, lozenges and dental care chewing gums will be used in the normal fashion and with regularity, if the effect is to be realized to its fullest degree.
• Example 1 Toothpaste Formulation A toothpaste can be prepared using the following ingredients and two different phosphates. Table 1 - Tube Formulations
• Sorbitol USP (70%) 29.9322 28.4761 Hydrated silicia (Zeofree 153) 8.000 7.000
• Titanium dioxide 0.7235 0.7235
• PEG-8 is a polyethylene glycol. It, along with the sorbitol and glycerin, is a humectant. Xanthan gum and the Zeofree 153 are binders and thickening agents. Three dyes are recited in this formulation as it is to be presented as a tri-colored product much like that sold under the Aquafresh brand name of SmithKline Beehcam Consumer Brands.
• the following formulation can be used with a pump dispenser system.
• Titanium dioxide 0.9560 0.9560 Sodium benzoate 0.100 0.200 Purified Water qs 100.00% qs 100.00%
• Example 2 Mouthwash Formulations An anti-caries mouthwash employing the pyrophosphates of this invention is illustrated by the following formulation.
• This mouthwash may be packaged in any conventional bottle or container.
• Dentifrices (toothpastes) were prepared in plain color-coded tubes. All had the same base to which was added a tripolyphosphate, pyrophosphate, or one of these phosphates with NaF. The control was the dentifrice base. The following table gives the concentrations of actives in each, formulation.
• test cell consisted often human tooth crowns which were removed from the roots, cleaned and painted with acid resistant varnish to leave test windows as described in detail previously (Featherstone et al, Caries Res. 1988; 22:337-341).
• Teeth were immersed individually for 6 hours daily at 37 °C in 40 mL of a buffer containing 0.075 mol/L acetate, 2.0 mmol/L CaHPO4 at pH 4.3. 5 2.
• Product immersion The crowns were removed from solution, thoroughly rinsed with double deionized water (DDW), and immersed individually in 4 mL of a 1:3 slurry of dentifrice (one of the test or placebo products, see below) in DDW, and stirred on an orbital shaker for 5 minutes. The slurries were made fresh daily within 30 minutes of
• Test Groups The experiments were carried out in duplicate, one group of each pair using sodium tripolyphosphate and one using pyrophosphate salts. The groups were designed to give four "cold" legs (Ai, A2, Bi, B2, below) which were assessed by cross-sectional microhardness testing (see below) to determine the degree of
• Bi Demineralization/remineralization cycling with 5 minutes daily immersion prior to remineralization in a 1:3 slurry of an sodium tripolyphosphate non-fluoride dentifrice (sodium tripolyphosphate present as in A but with no added sodium fluoride) (4 mL of solution per tooth individually).
• sodium tripolyphosphate non-fluoride dentifrice sodium tripolyphosphate present as in A but with no added sodium fluoride
• the sodium tripolyphosphate slurry was labeled with -2p as sodium tripolyphosphate added as a radiotracer prior to immersion of the teeth.
• C2- In the duplicate experiment pyrophosphate salts were used and similarly radiolabeled with ---P a s pyrophosphate salts.
• Groups A , A2, Bi, B2, and E were assessed by cross-sectional microhardness profiles, as described below.
• the duplicate radiotracer groups (C , C2, Dj, and D2) obviously could not be assessed in this manner. They were assessed by radiotracer counting as described separately below.
• indentation lengths were converted as per our published formula to volume percent, mineral and mineral loss ( ⁇ Z) values ( ⁇ m x vol % mineral) were calculated using Simpson's rule for each profile, for each lesion on each tooth, as described previously (White and Featherstone, Caries Res. 1987; 21:502-512). Mean values of ⁇ Z for each group were calculated, and mineral loss profiles were plotted as vol % mineral vs. depth from the outer surface.
• Radiotracer analyses Teeth from groups C and D were thoroughly washed in DDW and the varnish was removed individually from each tooth by acetone. Eight stepwise abrasions were made for each sample using small preweighed circles of silicon carbide paper (600 grade) to remove layers approximately 5 ⁇ m thick. Each sample was weighed, dissolved into a scintillation cocktail and the radioactivity counted in a Searle scintillation counter. Results for sodium tripolyphosphate and pyrophosphate salt products, with and without fluoride present, were compared. The amount of lesion formation was measured by the duplicate "cold" legs (A and B) described above as radiotracer material cannot be used in the other laboratories.
• Test material Human dental enamel from molars with caries free (by stereo microscope) buccal or lingual surfaces. Teeth were cleaned and prepared as described above for the pH cycling study. Artificial caries lesion formation: Artificial caries-like lesions were produced in one window (3 x 7 mm) on one enamel surface of molars prepared in our standard manner by immersion for 5 days in a pH 5.0 buffer (0.05 mol L lactate), 50 percent saturated with hydroxyapatite, and with 0.2% carbopol, as per the method of White (Caries Res. 1987: 21:228-242). This system produced lesions approximately 100 ⁇ m deep in 5 days.
• Teeth with preformed caries-like lesions were individually immersed in 20mL of a 1:3 slurry of sodium tripolyphosphate or pyrophosphate salts dentifrice with 3 p labeled sodium tripolyphosphate or pyrophosphate salts added at similar concentration as used in the pH cycling experiments above.
• Groups of 10 teeth each were used. The first group was immersed for one hour and the second group for 4 hours for each of sodium tripolyphosphate and pyrophosphate salts. At the end of the immersion period the teeth were removed, rinsed in DDW and immediately air dried. They were assessed for radiotracer uptake using the abrasion method as described above.
• 1 PPi means potassium pyrophosphate/sodium pyrophosphate (4.0%/1.81%)

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