PROCESSES AND COMPOSITIONS FOR REMINERALIZATION AND PREVENTION OF DEMINERALIZATION OF DENTAL ENAMEL

Abstract: The present invention relates to the problems of remineralization, without demineralization of dental enamel by applying to the teeth a composition which is present in two phases which do not react with one another until introduced into the oral cavity. One phase contains at least one water-soluble calcium compound and the other contains at least one water-soluble inorganic phosphate and at least one water-soluble fluorine compound. In this way the ions which effect remineralization can be absorbed by the dental enamel and their subsequent reaction causes rehardening of demineralized areas in the dental enamel.

Description: PROCESSES AND COMPOSITIONS FOR REMINERALIZATION AND PREVENTION OF DEMINERALIZATION OF DENTAL ENAMEL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to processes and compositions which are useful to rapidly remineralize subsurface dental enamel. More spec fically, this invention relates to salt solutions, such as calcium and phosphate salt solutions, which are applied to lesions in dental enamel resulting in remineralization of subsurface dental enamel and/or mineralizing tubules in dentin thereby counteracting caries and/or hypersens i tiv ty . 2. The Prior Art The primary component of the enamel and dentin in teeth is calcium phosphate in the form of calcium hydroxyapati te . This material is highly insoluble at normal oral pHs. However, carious lesions form in teeth, when they are subjected to acids produced from the glycolysis of sugars by the action of various oral bac¬ teria. This is because calcium phosphate salts are more soluble in acidic media. Saliva Is supersaturated with respect to calcium and phosphate ions. Saliva therefore helps protect teeth against demi neral izat ion and can slowly remineralize teeth which have become demi nera 1 i zed by acids. It is well known that the presence of fluoride ions can enhance the natural remineralization process and this is one of the accepted mechanisms by which fluoride toothpastes and rinses protect against caries. The efficacy of fluoride containing toothpastes and rinses to remineral ize teeth is l imited by the modest levels of calcium and phosphate in sal iva. It is evident from the prior art that it is highly desirable to increase the available concentration of calcium and phosphate ions in the oral cavity to speed up the remineralization process. However, because of calcium phosphate's low solubil ity at the pH of sal iva the addition of higher levels of dissolved calcium and phosphate ions is not easily accomplished. Remineralization of dental enamal has been carried out experimentally both in vivo and in vitro. Some studies have concentrated on the remineral i z ing properties of saliva and synthetic solutions supersaturated with respect of hydroxyapati te . Such studies comprise the subject matter of U.S. Patent Nos. 3,679,360 (Rubin) and 4,097,935 (Jarcho). Generally, the supersaturated solutions or slurries used in these patents for remineral ization experiments have been prepared from a single form of calcium phosphate. When a caries lesion is flooded with one of these supersaturated solutions, the calcium and phosphate ions in the form of precipitated hydroxyapati te remineral ize the lesion. However, these solutions are impractical for use for several reasons. First, the amount of calcium and phosphate ions available for remineralization in these supersaturated solutions is too low. It is reported that it takes approximately 10,000 unit volumes of the usual supersaturated solution to produce one unit volume of mineral . Thus, remineralization by this method requires both an excessive volume of fluid and an excessive number of appl ications. The supersaturated solutions are inherently limited in this respect because they cannot maintain their supersaturated state. When the hydroxyapati te precipitates out to the point where the solution is no longer supersaturated, new supersaturated solution must be introduced or the remineralization process stops. Another problem with single calcium phosphate slurries is that as the hydroxyapati te precipitates out of solution, the pH of the solution changes. Unless the old solution is removed from contact with the tooth material , the solution may become too acidic or alkaline and damage the dental tissue. U.S. Patent No. 4,080,440 (Digiul io et al ) discloses a metastable solution of calcium and phosphate ions at a low pH (between 2.5 to 4.0) underwhich conditions the solubil ity of calcium phosphate salts is high. After penetration of the solution into demineralized enamel , remineralization results from the precipitation of calcium phosphate salts when the pH rises. Fluoride ions can be included in the metastable solution. A significant disadvantage of the use of metastable solutions is that the relatively low pH might demineral ize the dental enamel and/or injure other tissue. U.S. Patent Nos. 4,177,258 and 4,183,915 (Gaffar et al) provide for a remineral iz ing solution containing supersaturated concentra ions of calcium ions, phosphate ions and a fluoride source stabil ized by the presence of an ant i nucl ea t i ng agent such as diamine tetramethyl enephosphonic acid. This solution is preferably adjusted to the neutral pH range where it is alleged to most effectively remineralize sub-surface lesions. Even though the antinucl eating agent would be expected to stabilize the solution, equilibrium of the supersaturated concentrations is still found difficult to maintain and avoid precipitation of hydroxyapatite and changes in the pH of the sol uti on . U.S. Patent Nos. 4,083,955 (Grabenstetter et al ) and 4,397,837 (Raaf et al ) provide a process for reminera 1 i zing demineral i zed enamel by the consecutive treatment of tooth surfaces with separate solutions containing calcium ions and phosphate ions. In this process fluoride ions may be present in the phosphate solutions. It is immaterial which ionic solution is used to treat the teeth first. By sequentially applying calcium and phosphate ions to the tooth surface high concentrations of the ions are able to penetrate into lesions in solution form, where they precipitate as a calcium phosphate salt when ions from the second treatment solution diffuse in. While apparently successful this method involves the inconvenience of a plurality of sequential applications which can also be found to be time consuming. Another problem with known remineralization techniques is that the remineralization may stop before the lesion is completely remineral i zed due to build up of the re i neral i zed tooth material in or on the outer layer of the tooth's surface. This build up occurs when the rate of remineralization is too fast and prevents the diffusion of the mineral into the deeper regions of the lesion, thus thwarting the full remineralization of the tooth . There is a need for a method of re ineralizing dental enamel that does not require excessive amounts of solution and inordinately long or frequent exposure times. It is the object of the present invention to provide a process and especially a composition for the remi eral ization and the prevention of demi neral i zat ion of human teeth, which process and composition are capable of effectively incorporating calcium ions, phosphate ions and fluoride ions into the dental enamel , the composition also being easily usable by the consumer and not differing significantly, in flavor and appearance, from customary dental cosmet i cs . SUMMARY OF THE INVENTION In accordance with the present invention the problems of remineralization, without demineral i zation are solved by applying to the teeth a composition which is present in two phases which do not react with one another until introduced into the oral cavity. One phase contains at least one water-soluble calcium compound and the other contains at least one water-soluble inorganic phosphate and at least one water-soluble fluorine compound. In this way the ions which effect remineralization can be absorbed by the dental enamel and their subsequent reaction causes rehardening of demi neral i zed areas in the dental enamel . It has been found that effective remi neral i z i ng treatments can be prepared by directly combining solutions or preparations with soluble salts containing high concentrations of calcium, phosphate and fluoride ions and applying them to teeth at moderate pHs. However, the calcium must be prevented from the reaction with the phosphate ions or fluoride Ions until immediately before use. This can be accompl ished by providing a dual container or tube system in which the calcium ions are in a different container or tube than the phosphate or fluoride ions or by incorporating undissolved soluble salts containing these ions into a single base in which the ions a re separated physically, e.g., by the encapsulation of at least one or are insoluble in said base . For two part systems, two part toothpastes, gels, professional gels, i.e. , those which are appl ied professionally or are obtained by a prescription, mouthwashes, and the like are prepared, wherein part I contains from about 0.05% to about 15% water-soluble calcium salt, and part II contains from about 0.05% to 15% water-soluble phosphate salt and from about 0.01% to 5% fluoride releasing agent such that when the two parts are mixed the pH is between about 4.5 and 10.0, and preferrably between about 5.5 and 7.0. The two parts are mixed and immediately appl ied to the teeth being treated. It has been found that such combinations produce rapid remineralization of lesions and are much more effective than conventional fluoride containing toothpastes in remi neral iz i ng teeth. The compositions of the invention give substantially improved remineralization and prevention of deminera 1 i zat ion of human teeth as compared with prior art compositions. The disadvantages of the prior art methods are overcome by the present invention which effects subsurface remineralization rather than surface remineralization. Since dental caries begins as a subsurface demineral izat ion of the dental enamel , subsurface remineralization arrests and repairs the carious lesion before any permanent structural damage to the tooth occurs. The present invention does not require preparation of the enamel surface, capping of the tooth, or removal of decay products. Further, the present invention may be conveniently practiced by the publ ic without substantially changing their dental care habits. DESCRIPTION OF THE INVENTION The present invention lies in the discovery that dental enamel may be remineral i zed by the application of certain soluble salts yielding ions which will react to form a desirable remineral i zing precipitate. The appl ication consists of the simultaneous use of a two part system wherein the first part is a reactant paste, gel or solution of a soluble salt which is placed in contact with the tooth surface. In this first reactant part are selected cations with diffuse through the tooth surface to its demi nera 1 i zed subsurface. In the second part a reactant paste, gel or solution containing selected anions is placed simultaneously in contact with the tooth surface. The anions diffuse through the tooth surface to the demi nera 1 i zed subsurface with the cations and form a precipitate which is bound to the tooth structure. As a result, the tooth's subsurface is remi nera 1 i zed when an effective amount of the two part system is utilized. By "effective amount of remi neral i z i ng system or agent" is meant an amount when used in accordance with this invention will bring about the remineral i z ing of teeth having caries lesions, or the mineralizing of normal teeth to prevent caries from forming by utilizing a toothpaste, gel , or mouthwash having the various components in the amounts set forth below. Concentrations of the soluble salt are from about 0.05 to 15% or the limit of solubility of the salt. Excess salt can be present, if desired. Concentrations from about 0.10% to 10% are preferred. The concentrations of the soluble salts containing the desired anions are essentially the same as those for the water-soluble salts containing the desired cations. Although many precipitates are within the broad scope of this invention, by depositing a precipitate less soluble than the original enamel , the remineral ized subsurface can be made to be more resistant to demineral i zat ion than was the original enamel. Due to the presence of a fluoride ion, the remineralized enamel is more resistant to demi neral i zat ion than was the original enamel . The concentration of salt containing fluoride ion in the solution may be from about 0.01% to 5.0%, but from about 0.02% to 2.0% is preferred. In order to effect remineral ization of the dental enamel , an effective amount of the desired cations and anions must be employed in the oral cavity. The amount of solution placed in the mouth must contain at least 100 pp of desired cations and 250 ppm of desired anions and preferably contains more than 3,000 ppm of desired cations and 3,000 ppm of desired anions. It is preferred to provide a level of fluoride ions between about 20 ppm to 5,000 ppm in the oral cavity from the dentifrice or professionally appl ied or prescribed gel . While the length of time of contact between the dissolved salts and the tooth's surface is not critical , it is necessary for the length of time to be great enough to allow diffusion of the ions through the tooth's surface to the demineral i zed subsurface. It is submitted that at least ten seconds is required for this diffusion and preferably it should be greater than thirty seconds. Each solution should have a pH of from about 4.5 to 10.0 and preferably between about 5.5 and 7.0 before and after the precipitation reaction, and be otherwise compatible in the oral environment. While some precipitation may occur, not all of the ions should combine prematurely in the solution to form a precipitate, but must be able to diffuse through the surface of the tooth to a deminera 1 i zed subsurface area and be able to form an insoluble salt with ions of the other solution. The solutions and the insoluble precipitates must have acceptable levels of toxicity (i.e. , the particular ions, in the amounts used in the remineral ization process, must be non-toxic) . In the preferred embodiment of the present invention, the remi neral i z i ng cationic solution contains about 0.05% to 15%, preferably about 0.10% to 10% of a dissolved calcium salt yielding calcium ions. The remineralizing anionic solution contains from about 0.05% to 15%, preferably about 0.10% to 10%, of dissolved phosphate salt yielding phosphate ions and from about 0.01% to 5.0%, preferably from about 0.02% to 2.0%, of a soluble fluoride salt yielding f1 uor ide ions . The resulting precipitate is a calcium phosphate or hydroxyapatite, the natural constituent of tooth enamel , with incorporated fluoride ions. Not only does this process result in remineralized enamel , but the remineralized enamel may be more resistant to subsequent deminera 1 i zat i on than was the original enamel . As the calcium compound it is, in principle, possible to employ, in the preparations of the invention, all water-soluble tox icol ogical 1 y harmless calcium compounds. A compound is considered to be water-soluble when Calcium nitrate is preferred. In the compositions of the invention for the remineralization of human dental enamel , at least about 100 ppm of calcium ions should be present; the upper limit is about 35,000 ppm of calcium ions . Suitable water-soluble inorganic ihates within the scope of the present 15 solubility in water is defined as in the case of the calcium compounds. If desired, water-soluble salts yielding both calcium and phosphate ions, such as monobasic-calcium orthophosphate , may be employed. The compositions of the invention for the remineral ization or prevention of demi neral i zati on of human teeth also contain water-soluble fluoride compounds, the caries-prophylactic activity of which has for a long time been considered to be established. These compounds are preferably present in the phase containing phosphate in order to avoid the formation of sparingly soluble calcium fluoride. Suitable fluoride compounds are the alkali fluorides such as sodium, potassium, lithium or ammonium fluoride, tin fluoride, indium fluoride, zirconium fluoride, copper fluoride, nickel fluoride, palladium fluoride, f1 uoroz irconates such as sodium, potassium or ammonium fl uoroz i rconate or tin f1 uoroz i rcona te , f 1 uoros i 1 i cates , f 1 uoroborates , f1 uorostanni tes . Organic fluorides, such as the known amine fluorides are also suitable for use in the compositions of the invention. Water-soluble alkal i metal monofluor- ophosphates such as sodium monof1 uorophospha te , lithium monof1 uorophosphate and potassium mono 1 uorophospha te , preferably, sodium monof1 uorophosphate may be employed. In addition other water-soluble monof1 uorophospha te salts may be employed including ammonium monofluoro- phosphate aluminum monof1 uorophospha te , and the like. If monofluorophosp ate salts are used as the fluoride source, they could be present in the first component along with the calcium cations without departing from the present invention. However, this is less desirable due to the potential loss of fluoride. Suitable toothpastes and gels can be made by employing in both the anionic and cationic portions of the toothpaste, from about 0.5% to 50%, preferably from about 5% to 25%, of an abrasive, from about 0.2% to 5% of a sudsing agent, from about 0.1% to 5% of a binding agent, from 0% to 50% of a humectant, and the balance, water and minors. The pH of a component part of the toothpaste or gel containing the active cationic ingredients preferably has a pH of more than about 3. The mixture of the two portions which is placed in the mouth, however, must have a pH of from about 4.5 to about 10.0 and, preferably, between about 5.5 and 7.0. The pH's of the cationic portion and the anionic portion can be adjusted so long as the above parameters are not exceeded . Suitable abrasives include silica xerogels. Other conventional toothpaste abrasives can be used in the compositions of this invention, and include beta-phase calcium pyrophosphate , dicalcium phosphate dihydrate, anhydrous calcium phosphate, calcium carbonate, zironium sil icate, and thermose tt i ng polymerized resins. Sil ica aerogels and the insoluble metaphosphates such as insoluble sodium metaphospha te can be used. Mixtures of abrasives can be also be used. Silica xerogel abrasives are preferred. Suitable sudsing agents are those which are reasonably stable and form suds throughout the period of application. Preferably, non-soap anionic or nonionic organic synthetic detergents are employed. Examples of such agents are water-soluble salts of alkyl sulfate having from 10 to 18 carbon atoms in the alkyl radical , such as sodium lauryl sulfate, water-soluble salts of sulfonated monoglycer ides of fatty acids having from 10 to 18 carbon atoms, such as sodium monoglycer ide sulfonate, salts of Cjn-Cis fatty acid amides of taurine, such as sodium N-methyl taurate, salts of C10~^ 18 fatty acid esters of i sethionic acid, and substantially saturated aliphatic acyl amides of saturated monoaminocarboxyl i c acids 18 having 2 to 6 carbon atoms, and in which the acyl radical contains 12 to 16 carbon atoms, such as sod ium-N-1 aury1 sarcoside. Mixtures of two or more sudsing agents can be used. A binding material is added to thicken and provide a desirable consistency for the present compositions. Suitable thickening agents are water-soluble salts of cellulose ethers, such as sodium carboxy ethy1 cellulose, hydroxypropy1 cellulose, and hydroxyethyl cellulose. Natural gums such as gum karaya, gum arabic, carrageenan and gum tragacanth, can also be used. Colloidal magnesium aluminum silicate, silica aerogels, silica xerogels, fumed silica, or other finely divided silica can be used as part of the thickening agent for further improved texture. A preferred thickening agent is xanthan gum. It is also desirable to include some humectant material in a toothpaste or gel to keep it from hardening. Suitable humectants include glycerine, sorbitol , polyethylene glycol , propylene glycol , and other edible polyhydric alcohols as well as mixtures thereof. Toothpaste or gel compositions may also contain flavoring agents such as oil of wintergreen, oil of pepper ent, oil of spearmint, oil of sassafras, and oil of clove. Toothpaste or gel compositions may also contain sweetening agents such as saccharin, dextrose, levulose, sodium cycla ate, and aspartame Mixtures of sugar with a sweetner, e.g. , sucralose, are contemplated. It is, of course, also possible to manufacture one or both phases in the form of a transparent gel , the gel-forming agents to be used including known thickeners, for example the alkali salts of polyacrylic acid, and also preferentially dehydrated silicon dioxide gels of particle size about 2 to 20 microns and specific surface area about 200 to 900 m^/g. The remineral izing systems herein can also be provided in the form of a mouthwash product. Both the cationic and anionic parts of mouthwashes can be made in accordance with the following. Mouthwashes generally comprise an aqueous solution of ethyl alcohol and flavoring materials. The alcohol provides an antibacterial effect, solubilizes the flavoring materials and provides a pleasant mouth feel ing. Alcohol-free mouthwashes are now, however, gaining in popularity. Optionally, mouthwashes also contain additional antibacterial agents and humectants such as glycerine and sorbitol which give a moist feeling to the mouth. Typically, mouthwashes contain about 0 to 30%, preferably about 0 to 20%, ethyl alcohol ; about 30% to 90% water; about 0 to 20% glycerine or other humectant; about 0 to 0.1% of an antibacterial agent; about 0 to 0.2% of a soluble fluoride source, about 0.01% to 0.5% of a sweetening agent, about 0.01% to 2.0% of a flavoring agent, and from about 0.1% to 1% of an emulsifier-surfactant. Examples of suitable flavoring agents include heliotropyl nitrile, wintergreen oil (methyl salicylate), oil of peppermint, oil of assia, oil of anise, oil of cinnamon, and mixtures thereof. Suitable sweetening agents include saccharin, glycerine, sorbitol , levulose, and 6- ( tr i bl uoromethy1 )-tryptophane and aspartyl pheny1 a1 an i ne methyl ester. In one embodiment of this invention there is provided a product for remi neral i z ing dental enamel comprising: (i) a first component comprising from about 0.05% to 15.0%, preferably about 0.10% to 10%, water-soluble calcium salt; (ii) a second component comprising from about 0.05% to 15.0%, preferably about 0.10% to 10% water-soluble phosphate salt together with from about 0.01% to 10.0% and preferably from about 0.02% to 5.0% fluoride releasing agent, (iii) a dispensing container comprising at least two discreet compartments each with an outlet end, the first compartment storing the first component which includes soluble calcium salt and the second compartment storing the second component which includes soluble phosphate salt together with the fluoride source, (iv) a closure mechanism for closing the compartments; and (v) wherein when the two components are mixed the pH in between about 4.5 and 10.0 and preferably between about 5.5 and 7.0. A plural ity of packaging methods may be employed in order to separately contain or store the two components and provide effective dispensing thereof Into the oral cavity. Thus, the two components of a toothpaste, gel , cream, or the like, may be simultaneously dispensed from separate collapsible tubes preferably made of plastic, a plastic and metal laminate, etc. For convenience and in order to aid in dispensing substantially equal amounts of the components, the tubes may be held together by banding or cementing, preferably along the corresponding ventral sides of the tubes. In another embodiment the two tubes may be constructed to have abutting, preferably flat, sidewall portions. In the forgoing embodiments the mouths of the tubes are usually sufficiently close so that sufficient quantities of the components of the toothpaste or gel may be simultaneously dispensed directly on the toothbrush with the tubes the being capped separately . Alternatively, another packaging method comprises loading each component of the paste or gel into separate compartments of the same collapsible composite tube, joined by a common orifice. Such composite tube has compartments separated by a divider which is firmly attached along substantially diametrically opposed portions of the sidewall , and corresponding portions of the head structure of the tube. The divider may be glued or welded to the sidewall and head structure of the tube during manufacture of the latter. The divider is preferably provided with a protruding portion which extends into the mouth of the tube until its edge is substantially flush with the rim of the mouth. Thus, a divider forms with the sidewall two separate compartments of substantially the same volume for storage of the cationic and aniomic components, respectively. In another alternative packaging method, the two tubes are "concentric". An inner tube lies within and parallel with an outer tube. The mouths of the tubes abut at the same point. Protrusions or the like are inserted between the inner and outer tubes so that the component contained in the outer tube can pass through an available space between the mouth of outer tube and the mouth of the inner tube. The closures of this tube-wi thi n-a- tube , (which can screw on the outer tube or simply be held by pressure), may, but does not have to be, equipped with an interior protrusion to fit in the inner tube in order to prevent premature intermixing of the two components at the mouth of the tube. The tubes of all the above embodiments are usually filled from the bottom and are subsequently sealed together by conventional techniques . Another alternative packaging arrangement comprises of a pressurized container which is provided with two compartments and two spouts. The internal pressure of the compartments is maintained by a pressurized gas, i .e., nitrogen, at the bottom of each compartment. Operation of a mechanical actuator actuates valves which release the contents of the compartments through the spouts causing discharge of the paste or gel components onto a brush . The mouthwash or rinse and similar liquid embodiments are maintained in a manner similar to the pastes or gels in that during storage, each of the components are maintained separate from one another to prevent premature reaction. Upon dispensing, the components mix and react in the oral cavity to effect remineralization of dental enamel . The l iquid components can therefore be stored each in separate compartments of a dual -compartment dispenser. The dispenser usually includes a closure system comprising for example, an incl ined crown portion, at least two pouring spouts extending upwardly from an upper surface of the crown portion and a cover for securement to the crown portion. The cover is provided with closure means, for example, depending plugs, to close the closure. Each pouring spout is preferably provided with a vent opening in addition to product orifices in the spouts. The orifices can be positioned close together on the crown, all of which assists in achieving control over pouring. Transparent containers have proven to be the most satisfactory. Transparency aids a person's ability to accurately and controllably dispense relatively equal volumes from a dual -compartment dispenser. Transparent walled containers also serve as a window function for gauging the amounts of liquid remaining in the dispenser. The walls of the containers can be scribed or otherwise calibrated to assist in dispensing the correct reminera 1 i z 1 ng amount of produc . While applicants do not wish the scope of the present invention to be limited by theory, it is believed that the calcium, phosphate, and fluoride ions diffuse through the tooth surface to the demi neral i zed subsurface and precipitate in the demi nera 1 i zed subsurface where they remineralize the tooth structure. This is surprising because sufficient calcium, phosphate, and fluoride ions remain soluble for a period of time sufficient to permit their diffusion into the demineral i zed subsurface of the dental enamel . This is accomplished by combining the particular ions just prior to their application to the tooth in a solution having a pH of about 4.5 to 10 and preferably from about 5.5 to 7 at which pH enough of the calcium, phosphate, and fluoride ions remain soluble for the period of time required to remi eralize the lesions of the dental enamel . As hereinbefore described, the calcium and phosphate ions are stored separately to avoid the premature precipitation of calcium phosphate . Chemically equivalent concentrations of the first and second solutions are not necessary as long as the molar ratio of calcium and phosphate ions in the mixture is from about 0.01 to up to 100 to 1. It is preferred that the ratio is from about 0.2 to 1 up to 5 to 1 , and it is most preferred that the ratio is about 1.67 to 1, the ratio of calcium to phosphate in natural tooth enamel (hydroxyapatite). While completely aqueous solutions are preferred in the present invention, non-aqueous solvents may be employed in combination with water. For example, suitable nonaqueous solvents include ethyl alcohol , glycerine and propylene glycol. Solvent systems suitable for use in the present invention are those which are capable of dissolving the salts employed in the invention and which are safe for use in the mouth. With regard to the period of time of exposure of the solutions to the teeth, it is necessary that the length of time be great enough to allow diffusion of the ions into the demi neral i zed subsurface. At least about ten seconds are required for this diffusion. The solution is preferably applied to the teeth for from about 10 seconds to about 5 minutes. The pH of the solution remains relatively constant after its introduction into the oral cavity. Calcium phosphate readily precipitates at this pH, but most surprisingly while some of the precipitation may occur immediately and some small amount even before appl ication to the teeth, sufficient calcium, phosphate and fluoride ions remain in solution to diffuse into the teeth and remineralize the demi neral i zed dental enamel . It is believed that the ability of the solutions to provide ions for remineralization is greatest upon their first introduction into the oral cavity, thereafter decreas i ng . The time period between the mixing of the first and second solutions and the appl ication of the mixture to the teeth should not exceed 1 minute, and preferably is less than l minute. With a toothpaste, gel , and the like, mixing is achieved on the surface to the teeth while brushing. The essence of the present invention l ies in the mixing of components and the quick and timely application of the resulting solution which will precipitate calcium phosphate, calcium fluoride, and calcium f 1 uoro-apat i te in the subsurface enamel of the teeth. Before such precipitation occurs, the mixture comprising the solution must quickly be applied to the teeth. Surprisingly, the solution can have a pH of about 4.5 to 10, but preferably about 5.5 to 7 to achieve this result. At a pH below about 3, demineral 1 zation occurs rapidly. A pH below 2.5 1s generally undesirable from a safety standpoint. The pH of the solutions of the present invention may be adjusted to the pH desired by methods well known in the art. The pH may be lowered by the addition of any acid which is safe for use in the oral cavity and which yields the desired pH at the amount employed. Examples of suitable acids are acetic acid, phosphoric acid, hydrochloric acid, citric acid and mal ic acid . The following Examples illustrate the invention: In the Examples and elsewhere herein parts and percent are by weight unless otherwise stated . Artificial lesions, about 50 μ deep, were formed in one surface of bovine enamel chips using a demineralizing Carbopol gel, which was used to treat the specimens for 72 hours. The surface hardness of the surface to be treated was then measured. The regimen cycle consisted of a 30 minute demineralization in a standard demineralizing solution followed by a 5 minute treatment of the test products diluted 1 part product to two parts human saliva, followed by a 60 minute remineralization in human saliva. Overnight, which was every fifth cycle, the specimens were kept with a layer of saliva and stored in a cold room. The test ran for three days, from a total of 15 demineralization:treatmentrremineralization cycles. For the treatment cycle, the two parts of the remineralizing test agents of the example were separately diluted 1 part product to 2 parts saliva and mixed together immediately before immersion of the enamel specimens. The two part oral remineralizing treatment was prepared as follows: Part Λ Part B Water Calc ium nl trate Dipotasslum phosphate Sodium fluoride 61 ycer in 25 25.00 Acet 1 c acid To adjust pll of ft B mixture of 5.5 Immediately after mixing. HARDNESS INCREASE OUE TO TREATMENT (Vickers Hardness Units) 1200 ppm Fluoride at Exa pl e 1 Crest pH 5.5 PI acebo 5 cycles 17.0 + 1.9 10 cycles 23.6 + 1.4 13.7 + 2.3 3.9 + 0.7 15 cycles 34.8 + 2.8 20 cycles 48.2 + 2.8 FLUORIDE INCREASE DUE TO TREATMENT ( ug/cm^) 1200 ppm Fluoride at Example 1 Crest pH 5.5 PI acebo 5 cycles 2433 1879 10 cycles 3523 2082 2928 244 15 cycles 4431 2196 20 cycles 4749 2964 The results show much greater remineralization, as measured by hardness increase and fluoride uptake, due to treatment with the product of Example 1 than Crest, fluoride solution or pi acebo . EXAMPLES 2, 3, and 4 Two part oral remineralizing treatments were prepared as follows: Example 2 Exam le 3 Exam le 4 CO ro To adjust pH of To adjust the pH of A 4 B mixture to A 4 B mixture to 5.5 immediately 4.5 immediately after mixing. after mixing. The same cyclic regimen used to evaluate Example 1 was used to evaluate the remineralizing efficacy of the above formulations compared with Crest. In this study 15 cycles were used. HARDNESS AN0 FLUORIDE INCREASE DUE TO TREATMENT Example 2 Example 3 Example 4 Crest Hardness increase 45.1 + 2.9 37.6 + 2.4 32.7 + 2.5 14.2 + 1.8 Fluoride uptake 4677 + 219 5686 + 138 4495 + 343 2099 + 182 The results show much greater remineralization, as measured by hardness increase and fluoride uptake, due to treatment with Examples 2, 3, and 4 of the invention than Crest. Examples 5, 6, 7. 8, 9 and 10 Two part oral remineralizing treatments were prepared as follows: Example 5 Example 6 Exam p le 7 A B A B Water 71.2 70.45 Calcium nitrate 3.8 0.00 Dipotassium phosphate 4.00 Sodium fluoride 0.55 Glycerin 25.0 25.00 Acetic acid To adjust pH of A 4 B mixture to 5.5 immediately after mixing. Example 3 Example 9 Example 10 Water 63.6 62.45 67.4 66.45 Calcium nitrate 11.4 0.00 7.6 0.00 Dipotassium phosphate 12.00 8.00 Sodium fluoride 0.55 0.55 Glycerin 25.0 25.00 25.0 25.00 Acetic acid To adjust pH of To adjust the pH of A 48 mixture to 5.5 A 4 B mixture to Immediately after 4.5 immediately mixing. after mixing. The same cyclic regimen used to evaluate Examples 1-4 was used to evaluate the remineralizing efficacy of the Examples 5-10 compared with Crest. In this study 15 cycles were used. HARDNESS INCREASE OUE TO TREATMENT Vickers Hardness Units Hardness Increase The results show much greater remineralization, as measured by hardness Increase, due to treatment with Examples 5-10 of the invention than Crest. Example 6 shows that even when the fluoride concentration Is lowered to supply only 27 percent of that supplied by Crest (i.e. 275 ppm versus 1150 ppm) much higher levels of remineralization are still achieved. Examples 11-16 Illustrate various embodiments remineralizing toothpaste formulations of the invention as follows: Example 17 illustrates an embodiment of a remineralizing Mouthwash formulation as follows:

Claims: WHAT IS CLAIMED IS: 1. A product for remineralizing dental enamel comprising: (i) a first discreet component comprising from about 0.05% to 15.0% of at least one water-soluble calcium salt; (ii) a second discreet component comprising from about 0.05% to 15.0% of at least one water-soluble phosphate salt; together with from about 0.01% to 5.0% of at least one water- soluble fluoride salt which yields fluoride ions; and (iii) wherein when the two components are mixed the pH of the mixture is between about 4.5 and 10.0. 2. The product according to claim 1 wherein the first component is comprised from about 0.10% to 10.0% of said calcium salt. 3. The product according to claim 1 wherein the second component is comprised of from about 0.10% to 10.0% of said phosphate salts. 4. The product according to claim 1 wherein the second component contains from about 0.02% to 2.0% of said fluoride salt. 5. The product according to claim 1 wherein the pH of the mixture is from about 5.5 to 7.0 upon mixing the two components. 6. The product according to claim 1 wherein the molar ratio of calcium and phosphate ions in the two components is from about 0.01 to 1 up to 100.0 to 1. 7. The product according to claim 6 wherein the molar ratio of calcium and phosphate ions in the two components is from about 0.2 to 1 up to 5.0 to 1. 8. The product according to claim 1 wherein each component is a paste, a gel or a profess ional gel . 9. The product according to claim 1 wherein each component is a l iquid mouthwash or rinse. 10. The product according to claim 1 wherein the first component contains from about 100 ppm to 35,000 ppm calcium ions, and the second component contains from about 250 ppm to 40,000 ppm phosphate ions and from about 20 ppm to 5,000 ppm f1 uor ide ions . 11. A product for remineral izing dental enamel comprising: (i) a first discreet component comprising from about 0.05% to 15.0% of at least one water-soluble calcium salt; ( i i ) a second di screet component comprising from about 0.05% to 15.0% of at least one water-soluble phosphate salt and from about 0.01% to 5.0% of at least one water-soluble fluoride salt which yields fluoride ions ; (iii) a dispensing container comprising at least two discreet compartments each with an outlet in proximity to the other, the first compartment storing the first component which includes calcium salt and the second compartment storing the second component which includes phosphate salt; (iv) a closure mecha ism for closing the compartments; and (v) wherein when the contents of the two compartments are mixed the pH of the mixture is between about 4.5 and 10.0. 12. The product according to claim 11 wherein the first component is comprised of from about 0.10% to 10.0% of said calcium salt. 13. The product according to claim 11 wherein the second component is comprised of from about 0.10% to 10.0% of said phosphate salt. 14. The product according to claim 11 wherein the second component contains from about 0.02% to 2.0% of said fluoride salt. 15. The product according to claim 11 wherein the pH of the mixture 1s from about 5.5 to 7.0 upon mixing the two components. 16. The product according to claim 11 wherein the molar ratio of calcium and phosphate ions in the two components is from about 0.01 to 1 up to 100.0 to 1. 17. The product according to claim 16 wherein the molar ratio of calcium and phosphate ions in the two components is from about 0.02 to to 1 up to 5.0 to 1. 18. The product according to claim 11 wherein each component Is a paste, a gel or a professional gel . 19. The product according to claim 11 wherein each component is a liquid mouthwash or rinse . 20. The product according to claim 11 wherein the first component contains from about 100 ppm to 35,000 ppm calcium ions, and the second component contains from about 250 ppm to 40,000 ppm phosphate ions and from about 20 ppm to 5,000 ppm f1 uoride ions . 21. An aqueous product for remineralizing dental enamel comprising: (i) a first discreet liquid component comprising from about 0.05% to 15.0% dissolved calcium salt; (ii) a second discreet liquid component comprising from about 0.05% to 15.0% dissolved phosphate salt and from about 0.01% to 5.0% of a dissolved fluoride salt; (iii) a dispensing container comprising at least two discreet compartments each with an outlet end, the first compartment storing the first component which includes dissolved calcium salt and the second compartment storing the second component which includes dissolved phosphate salt; (iv) a closure mechanism for closing the compartments; and (v) wherein when the two components are mixed the pH 1s between about 4.5 and 10.0. 22. The product according to claim 21 wherein each compartment contains about an equal quantity of component stored therein and a closure means for allowing the first and second components to be simultaneously dispensed from said compartments in about equal amounts. 23. A method for remineralizing dental enamel comprising: (i) dispensing a first component comprising from about 0.05% to 15.0% of at least one water-soluble calcium salt (ii) dispensing a second component comprising from about 0.05% to 15.0% of at least one water-soluble phosphate salt and from about 0.01% to 5.0% of at least one water-soluble fluoride salt; (iii) mixing said first component and said second component wherein the pH of respective components is such that the resulting mixture has a pH of from about 4.5 to 10; and (iv) applying said mixture as an aqueous solution to the teeth for a sufficient time that the calcium and phosphate ions from each of the salts diffuse into the subsurface of demineral 1 zed enamel and subsequently precipitate to form hydroxyapatite and remineralize the dental enamel . 24. The method according to claim 23 wherein said first and second components are a paste, a gel , or a professional gel and are extruded together onto a toothbrush. 25. The method according to claim 23 wherein the brushing takes place within about one minute after extruding said components and placing them onto the toothbrush. 26. The method according to claim 23 wherein the period of application of calcium and phosphate ions to the teeth is from about 10 seconds up to 5 minutes. 27. The method according to claim 23 wherein the first component is comprised of from about 0.10% to 10.0% of said calcium salt. 28. The method according to claim 23 wherein the second component 1s comprised of from about 0.10% to 10.0% of said phosphate salt. 29. The method according to claim 30 wherein the second component contains from about 0.02% to 2.0% of said water-soluble fluoride salt. 30. The method according to claim 23 wherein the resulting mixture has a pH of from about 5.5 to 7.0. 31. The method according to claim 23 wherein the molar ratio of calcium and phosphate Ions In the two components is from about 0.01 to 1 up to 100.0 to 1. 32. The method according to claim 32 wherein the molar ratio of calcium and phosphate ions in the two components is from about 0.2 to 1 up to 5.0 to 1. 33. The method according to claim 23 wherein the first component contains from about 100 ppm to 35,000 ppm calcium ions, and the second component contains from about 250 ppm to 40,000 ppm phosphate ions and from about 20 ppm to 5,000 ppm f1 uor ide ions . 34. A product for remineralizing dental enamel comprising: (1) a first discreet component comprising from about 0.05% to 15.0% of at least one water-soluble calcium salt and from about 0.01% to 5.0% of at least one water-soluble alkali metal monofl uorophosphate; (ii) a second discreet comprising from about 0.05% to 15.0% of at least one water-soluble phosphate salt; and (iii) wherein when the two components are mixed the pH of the mixture 1s between about 4.5 and 10.0. 35. The product according to claim 34 wherein the alkal i metal monof1 uorophosphate is sodium monof1 uorophosphate .

Inventors: USEN NORMAN, WINSTON ANTHONY E, USEN, NORMAN, WINSTON, ANTHONY, E.
Applicants: ENAMELON INC, ENAMELON, INC.
Application year: 1996
Main classification: A61K7
IPC codes: A61K8, A61Q11