Abstract:
Disclosed are compositions for the care and the cleaning of human teeth and dentures containing 1,6-di-4&#39;-chlorophenyldiguanidohexane (&#34;chlorohexidine&#34;) or the salts thereof and an amount of urea sufficient to reduce brown staining or discoloring of the teeth caused by the chlorohexidine. Also disclosed is a method of treating teeth and dentures comprising contacting them with urea and chlorohexidine.

Description:
FIELD OF THE INVENTION AND STATE OF THE ART 
     The effectiveness of 1,6-di-4&#39;-chlorophenyldiguanidohexane, which is also known by the common name, chlorohexidine, or the salts thereof in preventing the occurrence of or in removing human dental plaque has been known for some time as described in numerous publications. 
     The practical utilization of this knowledge, i.e., the actual use of chlorohexidine in dental and oral care products, has been discouraged until now by the fact that even after a short application of chlorohexidine, a deep brown staining of the teeth and often also of the tongue occurs. It has already been proposed to prevent this staining by the use of water-insoluble salts of chlorohexidine (see, for example, German Published Pat. application No. 2,158,102). This proposal, however, could not be utilized to the extent that the salts exemplified in this German Published Application, such as the dihydrochloride, are water-soluble to a certain extent. Completely water-insoluble salts cannot have any effectiveness. In the use of these chlorohexidine salts, which are not water insoluble but soluble with difficulty, there also occurs the disturbing staining of the teeth and the tongue, even if to a lesser extent. 
     BRIEF SUMMARY OF THE INVENTION 
     It has now been found that the brown staining of teeth and tongue as well as of dentures which occurs when using chlorohexidine-containing dental care and cleaning compositions may be avoided if urea is added to such compositions. The preferred amount of urea employed is between about 0.5% and a maximum of about 45% of the total care and cleaning composition, and the precise amount used depends, inter alia, on the form of application of the dental care product. The preferred quantity range is between about 1.0 to 35% by weight of the total composition. The novel care and cleaning compositions of the present invention may be in the form of toothpastes, mouth washes, tooth powder, tooth cleaning tablets, chewing gum, chewing and sucking dragees, or also as gel-shaped, transparent toothpastes. In the event the compositions are intended for the cleaning of dentures, they may be employed preferably in the form of powder or tablets. The proportion of chlorohexidine or its salts in the compositions of this invention is between about 0.01 and 7.5% by weight of the total composition (calculated on free chlorohexidine). 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As already stated, aside from chlorhexidine, per se, its preferably water-soluble salts may also be employed in the novel preparations disclosed. These salts, in particular, include the digluconate and the diacetate of chlorhexidine; however, there may also be employed the dipropionate, the diformiate, the dilactate, the dihydrochloride, the dihydrofluoride, the dibromide, the sulfate, the phosphate, the succinate, the pivalate, the citrate, the tartrate, the maleate, the malate, the disarcosinate, the monofluorophosphate or the hexafluorophosphate of chlorohexidine. The active chlorohexidine agent thus may utilize any salt-forming radical provided, of course, that it is non-toxic under the application conditions employed. 
     If the novel dental care and cleaning composition is in the form of a toothpaste or a tooth powder, it customarily will contain polishing, binding, thickening and moisture-holding agents. In addition to calcium carbonate and the various calcium phosphates, the preferred polishing agent is particularly dicalcium phosphate or calcium pyrophosphate and in addition to the insoluble alkali methaphosphates, aluminum hydroxide may be used. Silicon dioxide is also well suited as a polishing agent in the novel dental care agents, particularly in particle sizes of 2 to 20 microns. Suitable polishing agents useful in the present invention are thus any of the well-known and conventional agents known for this purpose. 
     When silicon dioxide is used as a polishing agent, there may also be prepared, by the corresponding standardization of the glycerin content, a transparent, gel-shaped toothpaste, which optically is especially pleasing to the consumer. 
     In addition to polishing agents, toothpastes also contain binding, thickening, and moisture-holding agents and any of such well-known agents may be employed. Suitable binding and thickening agents are, for example, alkali salts of polyacrylic acid, cellulose derivatives such as hydroxy ethyl cellulose, Irish moss, tragacanth, and other mucilages. 
     As the moisture-holding agents or humectants, particularly glycerin and sorbitol as well as other sugar alcohols and various lower aliphatic diols have proven suitable. 
     The novel dental care and cleaning compositions of the present invention will also customarily contain preserving agents, preferably p-hydroxybenzoic acid ester as well as chlorphene bromide or even the 1,3-bis-(β-ethylhexyl)-5-methyl-5-aminohexahydropyrimidine, known under the common name of Hexetidine. 
     The novel compositions furthermore may contain aromatic and flavoring agents. Saccharine sodium and sodium cyclamate, for example, may be used; the number of aromatic substances employable and their mixtures are practically unlimited and so well known to the art that they do not require an enumeration in detail. 
     The dental care agents, particularly mouth wash and toothpaste, are often added surface-active substances, e.g., for producing a foam when used. 
     The surface-active agents or tensides employed in the novel compositions must, of course, be compatible with the chlorohexidine or its salts. Such substances are, for example, higher alkyl sulfates and the salts thereof, e.g., sodium lauryl sulfate, salts of higher aliphatic acylamides of lower aliphatic amino acids, e.g., L-lauroylsarcosinate, protein fatty acid condensates in quantities of preferably not more than about 2.5% by weight, nonionic tensides, e.g., betaines, sulfobetaines or long-chain alkylamino carboxylic acids as well as cationic tensides, particularly quaternary ammonium compounds such as cetyltrimethylammonium bromide or diisobutylphenoxy ethoxyethyldimethylbenzylammonium chloride. 
     The novel dental care and dental cleaning compositions may also contain other substances known per se in dental and oral care agents besides chlorohexidine or the salts thereof, urea and the above-described customary agents and additives. Such substances, in particular, include the numerous fluorine compounds well known for the prevention of cavities such as sodium fluoride, potassium fluoride, alkali monofluorophosphate, stannous fluoride, manganese fluoride, long-chain aminofluoride, ethanolaminohydrofluoride, etc. 
     Also possible is the co-use of enzymes assisting the cleaning of teeth and the elimination of dental plaque, e.g., Dextranase or &#34;Mutanase&#34;, complex formers for calcium and magnesium, vitamins, inorganic and organic phosphates, allantoin, β-pyridylcarbinole or glycyrrhetinic acid and the derivatives thereof. 
     In the event the novel composition comprises a cleaning agent for dentures, it may contain, aside from chlorohexidine or its salts and urea, substances splitting off oxygen in the known manner, e.g., alkali persulfates and/or alkali perborates, complex formers, particularly water-soluble polyphosphates, e.g., sodiumtripolyphosphate, sodiumhexamethaphosphate or trisodiumphosphate or ethylene diaminotetracetic acid and, if necessary, surface-active, particularly cation-active and nonionogenic tensides as well as enzymes. 
     The concentration of the chlorohexidine in pulverulent or tablet-shaped cleaning agents for dentures is about 0.5 to about 25% by weight of the total composition. Where the novel composition is used in the form of a solution, a paste or a gel, the preferred chlorohexidine concentration is 0.05 to about 5% by weight of the total composition. The preferred urea concentration here also is between about 0.5 to a maximum of about 45% by weight of the total composition. 
     Given below are some examples for a more detailed explanation of the invention it being understood that such examples are for illustration only and do not limit the invention. The values given refer to percent by weight unless otherwise stated. 
     EXAMPLE I 
     TOOTHPASTE 
     
         Ingredients             Percent______________________________________hydroxyethylcellulose   0.90glycerin, 86%           10.00sorbitol, 70%           10.00water                   25.80chlorohexidine digluconate                   4.50 solution, 20%urea                    25.00dicalciumphosphate dihydrate                   20.00silicon dioxide, pyrogenic                   1.50methyl-p-hydroxybenzoate                   0.15aroma mixture           1.00sodiumlaurylsulfate     1.00saccharin sodium        0.15                   100.00______________________________________ 
    
     EXAMPLE II 
     TRANSPARENT TOOTHPASTE 
     
         Ingredients             Percent______________________________________hydroxyethylcellulose   0.30ethyl-p-hydroxybenzoate 0.15saccharin sodium        0.05glycerin, 99.5%         57.00water                   9.48aroma mixture           1.10chlorohexidine digluconate                   3.00solution, 20%urea                    15.00silicic acid (average particle                   12.50diameter 3-20 microns)sodium fluoride         0.22sodium lauryl sulfate   1.20                   100.00______________________________________ 
    
     EXAMPLE III 
     MOUTH WASH, READY FOR USE 
     
         Ingredients             Percent______________________________________ethanol, pure           5.000emulsifier              1.500aroma mixture           1.200sodium cyclamate        0.500water, desalted         82.799chlorohexidine digluconate                   1.000 solution, 20%urea                    8.000food coloring, red      0.001                   100.00______________________________________ 
    
     EXAMPLE IV 
     TOOTH CLEANING POWDER 
     
         Ingredients             Percent______________________________________dicalcium phosphate dihydrate                   54.0dicalcium phosphate dihydrate                   8.0 anhydridesilicon dioxide, pyrogenic                   2.5sodium monofluorophosphate                   0.8saccharin sodium        0.2sodiumlauroyl sarcosinate                   2.5chlorohexidine hydrochloride (B.P.)                   0.5urea                    30.0aroma                   1.5                   100.0______________________________________ 
    
     EXAMPLE V 
     TOOTH CLEANING TABLET 
     
         Ingredients             Percent______________________________________tragacanth              1.5polyvinyl pyrrolidone   0.3silicon dioxide, pyrogenic                   0.5dicalciumphosphate dihydrate                   70.0aluminum hydroxide      15.0aroma mixture           1.1polyethylene glycol 1000                   1.3chlorohexidine hydrochloride (B.P.)                   0.2urea                    10.0saccharin sodium        0.1                   100.0______________________________________ 
    
     EXAMPLE VI 
     CHEWING GUM 
     Introduced into a chewing gum base having a customary composition per 100 parts by weight of the total composition were 1 part chlorohexidine monofluorophosphate, 5 parts urea and 0.3 parts sodium fluoride, thoroughly mixed, rolled, and then strand cut into ready-to-use strips. 
     EXAMPLE VII 
     CLEANING TABLETS FOR DENTURES 
     
         Ingredients             Percent______________________________________sodium perborate monohydrate                   35.0trisodium phosphate     5.0sodium tripolyphosphate 15.0Potassium monopersulfate                   8.0sodium lauryl sulfoacetate                   0.5silicon dioxide, pyrogenic                   1.5peppermint oil          0.3polyvinyl pyrrolidone   2.0polyethylene glycol, 4000                   2.0tartaric acid           4.0sodium hydrogen carbonate                   16.6chlorohexidine hydrochloride (B.P.)                   0.1urea                    10.0                   100.0______________________________________ 
    
     EXAMPLE VIII 
     CLEANING POWDER FOR DENTURES 
     
         Ingredients             Percent______________________________________sodium perborate monohydrate                   40.0potassium monopersulfate                   5.0potassium sodium tripolyphosphate                   22.0silicon dioxide, pyrogenic                   2.2chlorohexidine acetate (B.P.C.)                   0.5urea                    30.0peppermint oil          0.3                   100.0______________________________________ 
    
     EXAMPLE IX 
     GEL-SHAPED CLEANING AGENTS FOR DENTURES 
     
         Ingredients             Percent______________________________________methylcellulose         0.8hydroxyethylcellulose   0.4glycerin                20.0sodium aluminum silicate                   1.0water                   46.0peppermint oil          0.3ethanol                 0.2chlorohexidine gluconate                   4.5 solution, 20%urea                    25.0saccharose monolaurate  2.8                   100.0______________________________________ 
    
     The above examples disclose compositions containing both urea and chlorohexidine. However, in treating the teeth or dentures, the application need not be simultaneous. For example, it has been found that a particularly good effect against dental plaque may be achieved and consequently an excellent teeth cleaning and caring of human teeth when the teeth are treated first with an agent, a toothpaste for example, containing about 0.5 to about 45% by weight urea and preferably an anion-active tenside, e.g., sodium lauryl sulfate, and subsequently the teeth are brought into contact with an agent, a mouth wash, for example, containing about 0.01 to about 7.5% by weight 1,6-di-4&#39;-chlorophenyldiguanidohexane. In this manner, the discoloring effect of chlorohexidine may also effectively be prevented.