water can comprise from about 50 % to about 80 % by weight , preferably from about 55 % to about 75 % by weight of the aqueous oral compositions of the present invention . these amounts of water include the free water which is added , plus that amount which is introduced with other materials . the aqueous oral composition of the present invention such as a mouthrinse is prepared using a vehicle which contains water and a humectant . the humectant is generally a mixture of humectants , such as glycerin and sorbitol , and a polyhydric alcohol such as propylene glycol , butylene glycol , hexylene glycol , polyethylene glocol . the humectant content is in the range of about 5 to abut 40 % by weight and preferably about 10 to about 30 % by weight . the water content is in the range of about 50 to about 80 % by weight and preferably 55 to about 75 % by weight . in the above identified antibacterial ester formula , r 2 co may be a natural system mixed fatty acid residue such as coconut oil fatty acid , tallow fatty acid residue and the like , or a mono - fatty acid residue such as lauroyl , myristyl , stearoyl and the like , the lauroyl group being preferred . examples of antibacterial ester salts of the above identified formula include inorganic acid salts such as hydrochloride , sulfate or an organic salt such as acetate , tautarate or citrate , the chloride salt being preferred . examples of antibacterial ester compounds preferred in the practice of the present invention are antibacterial ester compound of the above - identified formula wherein n in the formula equals 3 useful in the practice of the present invention include n α - cocoyl - l - arginine methyl ester , n α - cocoyl - l - arginine ethyl ester , n α - cocoyl - l - arginine propyl ester , n α stearoyl - l - arginine methyl ester , n α stearoyl - l - arginine ethyl ester hydrochloride . the term “ cocoyl ” is an abbreviation for coconut oil fatty acid residue , and chloride salts of these compounds , these ester compounds and the salts thereof being referred to in this specification as arginine derivative compounds . arginine derivative compounds and their salts in particular show excellent inhibitory effect against microorganisms which possess relatively strong resistance to bacterial such as s . aureus , s . mutans , f . nucleatum which are involved in plaque formation on teeth . an arginine derivative compound preferred in the practice of the invention is the hydrogen chloride salt of ethyl lauroyl arginine . the antibacterial ester of the present invention is present in the aqueous oral compositions at a concentration of about 0 . 05 to about 2 . 0 % by weight and preferably about 0 . 075 to about 1 % by weight . surfactants useful in the practice of the present invention include nonionic and zwitterionic surfactants . suitable nonionic surfactants useful in the present invention include poly ( oxyethylene )- poly ( oxypropylene ) block copolymers . such copolymers are known commercially by the non - proprietary name of poloxamers , which name is used in conjunction with a numeric suffix to designate the individual identification of each copolymer . poloxamers may have varying contents of ethylene oxide and propylene oxide which results in poloxamers which have a wide range of chemical structures and molecular weights . a preferred group of nonionic surfactants useful in the present invention include condensates of sorbitan esters of fatty acids with ethylene oxide ( polysorbates ) such as sorbitan mono - oleate with from about 20 to about 60 moles of ethylene oxide ( e . g ., “ tweens ”, a trademark of ici us , inc .). particularly preferred polysorbates are polysorbate 20 ( polyoxyethylene 20 sorbitan monolaurate , tween 20 ) and polysorbate 80 ( polyoxyethylene 20 sorbitan mono - oleate , tween 80 ). zwitterion surfactants useful in the practice of the present invention particularly betaine surfactants , include surfactants disclosed in u . s . pat . no . 5 , 180 , 577 , incorporated herein by reference . typical alkyldimethyl betaines include decyl betaine 2 -( n - decyl - n , n - dimethylammonio ) acetate , cocobetaine or 2 -( n - coc - n , n - dimethyl ammonio ) acetate , myristyl betaine , palmityl betaine , lauryl , betaine , cetyl betaine , cetyl betaine , stearyl betaine , etc . the amidobetaines are exemplified by cocoamidoethyl betaine , cocoamidopropyl betaine , laurmidopropyl betaine and the like . the preferred betaine is the cocoamidopropyl betaine . the surfactant is present in the aqueous oral compositions of the present invention range from about 0 . 1 % to about 5 % by weight preferably from about 0 . 6 % to about 2 . 0 % by weight . any suitable flavoring or sweetening material may also be incorporated in the mouthrinse composition of the present invention . examples of suitable flavoring constituents are flavoring oils , e . g ., oils of spearmint , peppermint , wintergreen , sassafras , clove , sage , eucalyptus , marjoram , cinnamon , lemon and orange and methyl salicylate . suitable sweetening agents include sucrose , lactose , maltose , sorbitol , xylitol , sodium cyclamate , perillartine and sodium saccharin . suitably , flavor and sweetening agents may together comprise from 0 . 01 % to 5 % by weight or more of the mouthrinse composition and at such concentrations render the mouthrinse with a palatability acceptable to the user . the oral composition of the present invention may additionally contain a fluoridating agent to aid in preventing dental caries as well as antibacterial metal salts , halogenated diphenyl ethers and enzymes . fluoridating agents suitable for use in the oral compositions of the present invention includes sodium fluoride , potassium fluoride , stannous fluoride and complex fluorides such as sodium monofluorophosphate . the fluoridating agent is most desirably present in an amount to provide 1000 - 2000 ppm fluoride ion in the composition . examples of antibacterial metal salts suitable for use in the present invention include stannous salts such as stannous chloride , stannous gluconate , zinc salts such as zinc chloride , zinc gluconate , zinc citrate and copper salts such as copper gluconate . examples of halogenated diphenyl ethers include triclosan and enzymes include papain and glycoamylase . these agents may be present in the composition of the present invention at concentrations of about 0 . 1 to about 2 % by weight . antitartar agents compatible with antibacterial esters such as ethyl lauroyl arginine may also be included in the oral composition of the present invention . an example of such antitartar agents include cationic polyphonates such as water soluble quaternary aminoalkylene phosphonic compounds as disclosed in u . s . pat . no . 4 , 118 , 472 , the disclosure of which is herein incorporated by reference . these antitartar agents may be included in the oral composition of the present invention at a concentration of about 0 . 1 to about 5 % by weight . antitartar agents which are not compatible with antibacterial esters such as pyrophosphate and polyphosphate salts may be included in one component of a dual component oral composition system in which a first component contains the antibacterial ester and the second component contains the incompatible antitartar salt , the first and second components being maintained separate from each other until dispersed and combined for application to the teeth . the following example further describes and demonstrates preferred embodiments within the scope of the present invention . the example is given solely for illustration , and is not to be construed as limitation of this invention as many variations thereof are possible without departing from its spirit and scope . a mouthrinse of the present invention having a ph of 5 . 0 was prepared by dissolving in water each of the ingredients listed in table i below with agitation in a glass mixing vessel . table i ingredient wt . % ethyl lauroyl arginate hcl ( elah ) 0 . 1 sorbitol 10 . 0 glycerin 10 . 0 propylene glycol 7 . 0 polysorbate 20 0 . 8 cocoamidopropyl betaine 0 . 8 sodium saccharin 0 . 03 flavor 0 . 10 water q . s . after 9 months at room temperature , the elah concentration was determined by gas chromatography — mass spectrometry to be unchanged at 0 . 1 % by weight . a double blind randomized clinical study was conducted in which 15 human subjects were asked to rinse for one minute with either the mouthrinse in example i or a matching placebo ( i . e ., without elah ) twice a day for 4 days while forgoing all other maintenance oral hygiene . there was a statistically significant reduction of 11 . 6 % in plaque using the mouth rinse of table i . the results of the study are recorded in table ii below . table ii clinical efficacy of an alcohol - free mouthrinse mouthrinse mean qhi * ( sd )** % reduction rel placebo placebo 2 . 51 ( 0 . 30 ) — 0 . 1 % elah 2 . 22 ( 0 . 22 ) 11 . 6 **
a stable aqueous antiplaque oral composition containing an antibacterial ester compound having the formula where r 1 is an alkyl chain of 1 to 8 carbon atoms , and r 2 is an alkyl chain of 6 to 30 carbon atoms and x is an anion , a surfactant ; a humectant ; and , wherein the composition is free of monohydric alcohol .