CA1187806A - Visually clear dentifrice - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A visually clear dentifrice containing a liquid vehicle compris-ing maltitol and water and a complex alkali metal aluminosilicate polishing agent is provided by use of a humectant having a refractive index of about 1.48. Increased free water can be used in the visually clear dentifrice without loss of clarity or undesirable drying of the dentifrice.

Description

This invention relates to a visually clear dentifrice.
More particularly, it relates to a visually clear dentifrice con-taining a liquid vehicle comprising maltitol and wa~er.
In recent years, visually clear dentifrices have been developed which contain a dental cleaning or polishing agent.
Such dental cleaning or polishing agents generally have been siliceous in nature with refractive indices of about 1.44 - 1.47.
Use of such materials has permitted preparation of dentifrices in which the refractive index of the liquid vehicle matches that of the siliceous polishing agent~ Thi.s has been typically accomplished using glycerin and/or sorbitol as humectants in the ; liquid vehicle, si.nce glycerin has a refractive index of 1.~73 and sorbitol (70% water solution) of 1.460 llowever, since water has a rcfractive index of 1.333, only very little formula water ~i.e. separate from that associated with other components ; such as sorbitol) could be used without substantially reducing the refractive index and causing diminution or loss of clarity.
Efforts have been made to develop visually clear denti-frices in which less glycerin and/or sorbitol could be tolerated.
For ins~ance: (1) In United States Patent 3,842,167 to Block et al maltodextrin was added as a non-humectant component of the liquid phase to reduce the amount of glycerin and/or sorbitol ::

needed; (2) in U. S. Patent 3,927,202 to Harvey et al various phosphate non-siliceous polishing agents were used which per-mitted modification of the refractive index range of the liquid vehlcle; in U. S. Patent 4,007,260 to Kim a silica polishing agent having a refractive index o~ about 1.410 to 1.440 was used.
It i9 an advantage of this invention that a visually clear dentifrice is provided in which a liquid vehicle i~ present which comprises ~a humectant having a refractive index of about 1.48 ~e.g. about 1.4750 to about 1.4849) and water.
It is a further advantage of this inven~ion that increased free water can be used above that prev$ously used in visually clear dentifriceæ containing an alkali metal aluminosllicate polishing agent naving a refractive index of about 1.44 to ahout 1.47 and a humecta~t having a refractive index of ahout 1.48.
The amount of water 15 not so h$gh as to result in undesirable drying of the dentifrice due to substantial evaporation of water, particularly in view of the presence of maltitol~ Other advantages will be apparent from consideration of the following specific~tion.
In accordance with certain of i~s aspects, this invention relates to a visually clear dentifrice conta1ning a vehicle comprising about 0.5-10% by weight of a solid portlon of gelling agent and about 50-94.5YO by weight of a liquid portion compris-ing (a) a humectant ~herein maltitol of refractive index of about 1.48 is present as the sole or na~or non-water componen~
of said llquid vehicle and (b) water in amount to provide a refractive index to said liqtlid vehicle of between about 1.44 a~d about 1.47, said vi5u811y clear dentifrice also containing about 5-50% by weight of a complex alkali metal aluminosilicate pollshing agent navlng a refractive index between about 1.44 to about 1.47.

Ihe li~uid portion oE tile vehicle comLlrises about 50 -94.5 % by weigh-t of the visually clear dentiEr:ice, ~preferably about 55 - 80%. It contaills a h-mect~mt wh:icll is all or a major amount ~i.e. above about 50 %) of maltitol. Maltitol* is essen-tially a glycosyl sorbitol, i.e. 4-D-~-D-glycopyranosyl-D-glucitol, having the structural Eormula:

CH20~1 ~ HO-CH
HO o C~l H HO HC-OH
HO-CII

It is prepared by hydrogenation oE maltose. In substantially pure form i-t is a glassy solid. It readily dissolves in minor amounts of water and its solutions containing at least about 73 % oE
maltitol and up to about 27 % of water are observed to have refrac-tive indices of about 1.48. ~i.e. about 1.4750 to 1.4849). When incorporated into a dentifrice together with separately added wa-ter of refractive index of about 1.333, the liquid vehicle can be ad-justed to provide a refractive index of about 1.44 to about 1.48.
Typically, about 5 - 25 % by weight of water can produce such a refractive index, with lower amounts of water (e.g. about 1.47) and higher amounts of water (e.g. about 15 - 23 %) producing a lower refractive index ~e~g. near 1.44). Preferably, the refrac-tive index of the liquid vehicle is about 1.44 to 1.'17 and is attained with about 5 - 10 % by weight of formula water. The water portion of the dentifrice refers to water which is separate or unassociated with water used to dissolve humectant.

*Trade Mark - 3 -.. .. .

Ma:lti-tol need not be pure in the sense of heing the sugar a]cohol derivative of pure maltose. Commercial maltitol consists of maltitol with minor amounts of the sugar alcohols derived from maltotritose, maltotetrose, and related low molecule weight malto-dextrin portions of corn syrup and with minimal amounts of D-sorbitol. Thus a commercial "hydrogenated starch hydrolysate"
made from high maltose content corn syrup would also be useful in the practice of this invention.
Maltitol has been recommended for dentifrice use, albeit not as a principal humectant for visually clear dentifrice containing a polishing agent.
In this regard reference may be had to "Caries Research", Vol. 14, Issue 2, ~19~0) pages 67-74, Rundegren et al (maltitol observed not to contribute to demineralization); "Shigaku", Vol. 60, Issue 6 ~1973), pages 760 - 765, Matsuo ~maltitol observed not to be fermented by Streptococcus salivarius, S.); "Acta Odont. Scand", Vol. 37, Issue 2, ~1979) pages 103 - 115, Bi.rkhed et al and "Caries Research", Vol. 12, Issue 3 ~1978), pages 128 -136, Birkhed ~observations made on plaque) "Acta Odont. Scand, Vol. 35, Issue 5 (1977), pages 257 - 263, Edwardsson et al (observations made on oral bacteria); Japanese Patent Publication 73 10241 of Sunstar (describing maltitol as a mouthwash compo-nent). Further, maltitol may be a component of a vari.ant of sorbitol known as "non-crystalizing sorbitol", which may be used as a dentifrice humectant. ~lowever, the substantial content of sorbitol in non-crystalizing sorbitol is such that a refractive index of about 1.48 is not achieved, thereby reducing water-humectant vehicle formulation variation ability in comparison with that of the present invention. It is also noted that fatty acid esters of maltitol and other sugar alcohols are disclosed as dentifrice taste components in British Patent Specification

2 038 182 of l.ion Dentifrice Company.
If desired, the liquid vehicle of the visually clear den~ifrice of the present invention may be a minor amount (i.e.
less than about 50%) of a humectant in addition to ma]titGl or even a non-humectant liquid vehicle component such as maltodextrin.
Such humectants as glycerin, sorbitol (typically 70% solution of sorbitol), polyethylene glycol 400, polyethylene glycol 600, and the like may be used. Preferably, maltitol comprises above about 50% by weight of the non-water portion of the liquid vehicle, preferably about 65 - 100%. Maltitol is typically provided in about 73 - 85% solution and is available from suppliers including Aldrich Chemical Company, Merck and Co. Inc., Imperial Chemicals Industries, Pfizer Inc., Lonza, Roquette ~reres, and Hayashibara Chemical Laboratories.
The solid portion of the vehicle is a gelling agent, such as the natural and synthetic gums and gum-like materials, such as Irish Moss, gum tragacanth, alkali metal carboxymethyl cellulose and hydroxyethyl carboxymethyl cellulose, polyvinyl pyrrolidone, starch, xanthan, guar gum, sodium alginate, hydro-philic colloidal carboxyvinyl polymers, such as those sold under the ~rademark Carbopol 934 and 940 and synthetic inorganic silicated clays such as those solid under the trademark Laponite CP and Laponite SP. These grades of Laponite have the formula ~Si8Mg5 lLio 6H7 624~ Na o 6 The solid portion of the vehicle is typically present in amount up to about 10% by weight of the dentifrice and preferably about 0.25 - 5% by weight. When employed, grades of Laponite are typically used in amounts of about 1 - 5% by weight.

Synthetic finely divided sil:icas such as those sold under the trade marks Cab-0-Sil M-5, Syloid 2~4, Syloid 266, Aerosil D200 and mixtures thereof, may also be employed in amounts of about 0.5 - 20% by weight to promote thickening or gelling and clarity of the dentifrice.
The complex alkali metal aluminosilicate salt des-cribed above is typically alkaline in nature, typically a sodium salt~ and effectively promotes oral hygiene. It is an amorphous powder which further has the property that when incorporated in the vehicle the particles thereof become substantially invisible.
Thus, a particle size for the polishing agent is up to about 40 microns, preferably 1 - 2 microns. The typical moisture content, measured by loss on ignition, is about 5 - 20% by weight of the agent and the typical content of alkali metal oxide, such as sodium oxide is up to about 10% by weight. Alumina is typically present in amount of about 10% by weight and silica typically in amount of at least about 70% by weight, typically the agent has a loose bulk density o:f up to about 0.2 g/cc preferably about 0.07 - 0.12 g/cc. The amount of alumina in the aluminosilicate is typically about 0.1 - 3% by weight and preferably about 1%.
Desirably the refractive index of the aluminosilicate is within about 0.005 units~ typically within about 0.001 of that of the liquid vehicle.
The polishing agent typically comprises about 5 - 50% by weight of the dentifrice formulation, preferably about 10 - 30%
by weight.
The complex alkali metal aluminosilicate salt appears to contain interbonded silica and alumina having Al - - 0 Si bonds as described by Tamele "Chemistry of the Surface and the Activi*y of Alumina-Silica Cracking Catalyst1', Discussions of the Faraday Society, No. 8, Pages 270 - 279 ~1~50) and particularly at page 273, Figure 1, curve, 3 wherein the interaction between silica and aluminum ions is potentiometrically detected. Further literature describing this type of complex includes Milliken et al, "The Chemical Characteristics and Structures of Cracking Catalysts", Discussion of the Faraday Society, No. 8, pages 279-290 (1950) and particularly the sentence bridging pages 2~4-285. These complexes clearly differ from sillca gel as is described by Plank et al. "Differences Between Silica and S~lica-Alumina Gels I. Factors Affecting the Porous Structure of These Gels,"
Journal of Colloid Science, 2, pages 399-412 (1947) and Plank, "Differences Between Silica and Silica-Alumina Gels II. A Pro-posed Mechanism for the Gelation and Syneresis of The~e Gels,"
Journal of Collold Science 27 pages 413-427, (1947) in which formation of the Al _ O ~ Si bond is described at pages 419-422.
The aluminosilicate may be described as silica containing combined alumina.
In the prior art, maltitol ~as disclosed for use in denti-frlces in Japanese P~tent Publicatio~ 15120/65 ~Patent No.
4619281) and 73¦10241. In the former, siliceous polishing agent is not disclosed; in the latter sllicic anhydride is mentioned as a polishing agent. However, it has been found that when silicic anhydride, such ~s colloidal silica xerogel available from Grace Davison as Syloid 74 is employed in a visually clear dentifrice cont~inlng msltitol, the dentifrice qulckly becomes dull in appearance and dries when exposed to air to become a hardened opacified product. When the complex alu~inosilicate of the preæent in~ention is employed the dentifrice substantially retains its desirable clear appearance and rheology.
Organic surface-active agents may be used in the compositions of the present invention to achieve increased prophy~actic action, aSSiBt in achievlng thorough and complete dispersion of _7-,, the instant compositions ~hroughout the oral cavity, and render the instant compositions more cosmetically acceptable. The organic surface active material may be anionic, nonionic, ampholytic) or cationic in nature, and it is deslrable to employ as the surface active agent a deterslve materlal which $mparts to the composition detersive and foaming properties. Suitable types Gf such detergents are water-soluble salts of higher fatty acid monoglyceride monosulphates, such as the sodium salt of the monosulphated monoglyceride of hydrogenated coconut oll atty acids, higher alkyl sulphates, such as sodlum lauryl sulphate, alkyl aryl sulphonates, such as sodium dodecyl benzene sulphonate, olefin sulphonatesp such as sodium olefin sulphonate ln which the olefin group contains 12-21 carbon atoms, higher alkyl snlphoacetates, higner fatty acid ester of 1,2-dihydroxy propane sulphonates, and the substantially saturated hlgher aliphatic acyl amides of lower aliphatic amino carboxylic acid compounds~
such as ~hose having 12-16 carbons ln the fatty acid, alkyl or acyl radicals, and the like. Examples of the last mentioned amides are N-lauroyl sarcosine and the sodium, potassium, and ethanolamine salts of N-lauroyl, N-myristoyl or ~-palmitoyl sarcosine, whlch could be substant~ally free from soap or similar higher fatty acid material ~hich tends to substantially reduce the effect of these compounds. The use of these sarco~ine compounds in dentilrice compositions of the present inventlon is particularly advantageous since these materlals exhiblt a prolonged and marked effect in the inhibltion of acid formation in the oral ca~ity due to carbohydrates breakdown in addition to exerting some reduction in the solubility of tooth enamel in acid solutions.
Other partlcularly suitable surface active materials include nonionic agents such as condensates o~ sorbitan monostearate with appro~imately 20 moles of ethylene oxide9 condensates of propylene glycGl ("Pluronics") and amphoteric agents such as quaternized imidazole derivatives, which are available u~der the trademark "Mi~anoll' such as Miranol G2M. Cationic surface active germicides and antibacterial compounds such as di-isobutylph~no-xyethoxyethyl dimethyl benzyl ammonium chloride, ben~yl dlmethyl stearyl ammonium chloride, tertiary amines having one fatty alkyl group (of from 12-18 carbon atoms~ and two (poly) exye~hy lene groups attached to the nitrogen (typically containing a total of from about 2 to 50 ethano~y groups per molecule) and salts thereof with acids, and compounds of the structure.

(IH2cH2o)zH CH2CH2~)xd R-N C~2CH~CH2N (cH2cH2o3yH

where R i3 a fatty al~yl group containing fro~ abou~ 12 to 18 carbon atoms, and x, y and z total 3 or h-lgher, as well a~ salts thereo with mineral or organic acids, may al~o be used. It is preferred to use from about ~.05 $o 5~ by weight of the foregoing surface-active ma~erials in the instant dentifrice.
An alkall metal fluorine-providing compound may be employed in the dentlfrice of the invention. The alkali metal fluorine-providing compound includes sodium fluor~de, potassium fluoride, lithium fluoride, ammonium fluoride and complex fluorides, par-ticularly alkali metal monofluorophosphates. These compounds exhibit satisfactory retentions of soluble fluoridP in denti-frlces of the instant invention. In particular, the level of retention of monofluorophosphate lon as fluoride wlth the alkali~`
metal monof luorophosphates is quite high. The fluorine-contain-ing compound ls emp:LoyPd in amount which provides an effective non-toxic amount of fluorine-containing ion to thP dentifrice _g_ ,, ~7~3~6 typlcally about 0.01-1% by weight preferably about 0.1% f luorine .
Thus, sodium fluoride i~ typically employed ln amount of about 0.02-2% by weight, pref erably about 0.2X, and sodium monofluoro-phosphate, Na2P03F, in amount of about 0.1-7.6% by weight, preferably about 0.76%.
The alkali metal monofluorophosphat~ which may be employed include sodium monofluorophosphate9 lithium monofluorophosphate, potasslum monofluorophosphate and ammonium monofluorophosphate.
The preferred salt is sodium ~onofluorophosphate, ~a2P03F, which, as co~mercially available, may vary cons~dersbly ln purity. It may be used in atly suitable purity provided that any impurities do not substantially adversely affect the desired properties.
In general, the purlty is desirably at lea~t about 80%. For best results, it should be at least 85%, and preferably at least 90%
by weight of sodium mo~ofluorophospha~e wi~h the balance being primarily impuritie~ or by-products of manufacture such as sodium fluoride, water-soluble sodium phosphate salt, and the like. Expressed ln another way, the sodium monofluoropho~phate employed should hava a total fluoride content of about 12%, preferably about 12.7%; a eontent of not ~ore than 1.5%, pre-ferably not more than 1.2% of free sodium fluoride; and a sodium monofluorophosphate content of at least 12%, prefersbly at least 12.170, all calculated as fluGrine.
Other monofluorophosphate salts whlch may be used in the ins~ant inventlon include monofluoropolyphosphates such as 4PgOgF, K4P309F~ 4)4P30gF, Na3KP~09F9 ~N~)3MaP309F and Li4P309F-Any suitable flavor~ng or sweetenlng ma~erials may beemployed in for~ulating a flavor for the compositions of tbe present invention. E~amples of sui~able ~lavouring con~tituents include the flavouring oil~, e.g., olls of ~pearmint, peppermi~t, _10 -

3'7~

wintergreen, sassafras, clove, sage, eucalyptlls, majoram, cinna-mon, lemon and orange, as well as methylsalicylate. Suitable sweetening agents include, sucrose, lactose, maltose, sorbitol, sodium cyclamate, perillartlne and saccharin. Suitable, flavor and sweetening agents may together comprise from about 0.01 to 5% or more of the compositions of the instant invention.
Chloroform may also be used.
Antibacterial agents may be employed in the prepara-tions of the instant invention in an amount of about 0.01 to 5% by weight. Typical antibacterial agents include Nl-(4-chlorobenzyl)-N5-(2,~-dichlorobenzyl)biguanide;
P-chlorophenyl biguanide;
~-chlorobenzhydryl biguanide;

4-chlorohenzhydrylguanylurea;
N-3-lauroxypropyl-N5-p-chlorobenzylbiguanide;
1,6-di-p-chlorophenylbiguanidohexane;
1,6-bis(2-ethylhexylbiguanide)hexane;

l-(lauryldimethylammonium)-8-(p-chlorobenzyldimethylammonium) octane dichloride;

5,6-dichloro-2-guanidinobenzimidazole;
Nl-p-chlorophenyl-N5-laurylbiguanide;
5-amino-1~3-bis(2-ethylhexyl)-5-methylhexahydropyrimidine;
and their non-toxic acid addition salts.
Various other materials may be incorporated in the pre-parations of this invention. Examples thereof are colouring or whitening agents or dyestuffs, preservatives, silicones, chloro-phyll compounds, ammoniated materials such as urea, diammoniumphos-phate and mixtures thereof, and other constituents. The adjuvants are incorporated in the instant compositions in amounts which do not substantially adversely affect the properties and character-istics desired and are selected and used in proper amounts depending upon tlle particular type of preparation involved.

7~

Tlle dentiEricos should ilave a p~l prac-ticable for use. A
moderately acid to alkaline pll is preEerred.
The following specific examples are further illustrative of the nature of the present invention, although it is understood that -the invention is not linlited thereto. All amounts are by weight unless otherwise indicated.
EXAMPLF. 1 The following denti:Erices are prepared:
PARTS
A B
Maltitol* (80 %) 59 % 59 0 Deionized water 10.74 10.7~
Sodium monofluorophosphate 0.76 0.76 Sodium saccharin 0.25 0.25 Sodium carbox~nethyl cellulose 0.35 0.35 Polyethylene glycol (Carbowax* 600) 3.0 3.0 Silica xerogel (Syloid* 74) 18.0 Sodium aluminosilicate ~silica containing about 1 % combined alumina - Zeo 49B*-Huber) - 18.0 Sodium lauryl sulfate 1.2 1.2 Flavor 1.2 1.2 The reEractive index of Syloid 74 in Dentifrice A and Zeo 49B in Dentifrice B is within about 0.005 unit of that of the liquid vehicle of each dentifrice.
Each of the dentifrices are initially shiny and clear.
However, after one week at room temperature, Dentifrice A, contain-ing silica xerogel, becomes dull in appearance and upon being left exposed to air becomes opaque white-like color and quite hard.
~nder these sc~ne conditions, dentifrice B remains shiny *Trade Mark - 12 -"'~

and clear and continues to have desirable flow characteristics.

_XAMPLE 2-4 The following visually clear dentifrice~ are prepared ln which the refractive index of the polishing a~ent is within 0.005 unit of that of the liquid vehicle.
PARTS
_ _ 3 4 Maltitol (73%) 62.0 - -Maltitol (80%) - 60.0 48.0 Deionized water 7.24 16.6 22.6 Sodium monofluorophosphate0.76 0.76 0.76 Sodium saccharin 0.25 0.24 0.24 Sodium benæoate 0.50 -- -Sodium carboxymethyl cellulose 0.35 0.4 Xanthan - - 1.4 Polyathylene glycsl (Carbowax 600) 3.00 Sodium aluminosllicate ~Silica con-taining about 1~. combined alumina-Zeo 49A in Example 2 and Zeo 49B in18.00 20.00 20.00 ~xamples 3 and 4 (Huber) Silica thickener (Syloid 244) 5.50 Sodium lauryl sulfate 1.20 1.20 1.20 Flavor 1.20 0.80 0.80 Although this invention ha been described with regard to ~llustrative examples, it wlll be apparent to one skllled in the art that various modiflcations may b~ made ~hareto which fall within its scope.

Claims (8)

CLAIMS:

1. A visually clear dentifrice containing a vehicle compris-ing about 0.5-10% by weight of a solid portion of gelling agent and about 50-94.5% by weight of a liquid portion comprising (a) a humectant wherein maltitol of refractive index of about 1.48 is present as the sole or major non-water component of said liquid vehicle and (b) water in amount to provide a refractive index to said liquid vehicle of between about 1.44 and about 1.47, said visually clear dentifrice also containing about 5-507. by weight of a complex alkali metal aluminosilicate polishing agent having a refractive index between about 1.44 to about 1.47.

2. The visually clear dentifrice claimed in Claim 1 wherein maltitol is present in aqueous solution containing at least about 73% by weight of maltitol.

3. The visually clear dentifrice claimed in Claim 2 wherein maltitol is present in aqueous solution containing about 73-85%
by weight of maltitol.

4. The visually clear dentifrice claimed in Claim 3 wherein the maltitol solution comprises about 65-100% by weight of the non-water portion of said liquid vehicle and the water portion of said liquid vehicle comprises about 5-25% by weight of said denti-frice, the water in said water portion being unassociated with humectant.

5. The visually clear dentifrice claimed in Claim 1 wherein said alkali metal aluminosilicate is sodium aluminosilicate.

6. The visually clear dentifrice claimed in Claim 5 wherein said sodium aluminosilicate contains about 0.1-3% alumina in com-bination with silica.

7. The visually clear dentifrice claimed in Claim 6 wherein said sodium aluminosilicate contains about 1% alumina in combina-tion with silica.

8. The visually clear dentifrice claimed in Claim 1 wherein the refractive index of said sodium aluminosilicate is within 0.005 units of that of said liquid vehicle.