CA1260839A - Astringent dentifrice - Google Patents

Abstract

ASTRINGENT DENTIFRICE
ABSTRACT
Astringent dentifrice containing a water-soluble zinc salt and a hydrous silica gel polishing agent compatible and substantially non-reactive with the zinc salt. The astringent dentifrice may additionally contain alkali metal monofluorophosphate, alkali metal carboxymethyl cellulose or combinations thereof, each of which is substantially non-reactive with the zinc salt and the hydrous silica gel.

Description

~Z6(;P~35~

This invention relates to a dentifrice containing a water-solub]e zinc salt which provides an astringent effect on oral mucosa and periodontal tissue during toothbrushing, and optionally an alkali metal monofluorophosphate or a gelling agent, or both.
Each of the components is compatible and substantially non-reactive with a hydrous silica gel polishing agent.
The astringent effectiveness of zinc ions provided by water-soluble zinc salts to promote and improve oral hygiene has long been known. Nevertheless, there have been limits on the practical use of zinc in dentifrice compositions since zinc ions can readily react with typical dentifrice components causing substantial loss of availability of zinc ions.
Likewise, the monofluorophosphate ion has long been known to promote oral hygiene and reduce caries formation by release of fluoride but its effectiveness too has been reduced by incompatibility with some dentifrice components, such as water-I soluble zinc compounds. ~, Nonionic gelling agents such as hydroxyethyl cellulose havebeen preferably used in dentifrices when water-soluble zinc salt j is employed. However, when alkali metal carboxymethyl cellulose has been employed in the presence of zinc ions, reaction occurs removing zinc ions, leading to possible gel breakdown and phase separation. In U.S. Patent 3,728,446, to Roberts et al, the l in situ reaction between zinc ions and alkali metal carboxymethyl cellulose to form vislùle particles i9 described.

. I . .

lZ60839 ,1 Furthermore, gel-type dentifrices providing zinc astringency ~¦ have been limited due to the incompatibility of zinc ions with various siliceous polishing agents. Such siliceous polishing agents as silica xerogel having an average particle size between about 2 and 20 microns and generally a surface area of at least about 300 m2/gm, typically about 300-370 m /gm, or about 1 600-800 m /gm, which are described in U.S. Patent No. 3,538,230 Il to Pader et al, undergo in situ reaction with zinc ion so that ¦I much of the theoretically available zinc is lost by physio-chemical means such as absorption.
Similar compatibility problems would occur when water-soluble zinc salt is present together with other dentiErice salt polishing agents, particularly calcium salts such as dicalcium phosphate or ca]cium carbonate. In fact, it has been believed that it would Ij be difficult to employ water-soluble zinc salt and mainta:in high j~ level of availability of zinc ions in such conventional 1I dentifrices.
¦I Compatibility is also a problem when alkali metal monofluorophosphate is employed with such siliceous polishing agent in a dentifrice containing a water-soluble zinc salt.
It has therefore been difficult to prepare dentifrices containing siliceous polishing agent and amounts of zinc ions ; with or without alkali metal monofluorophosphate or alkali metal ..

~Z6(~839 carboxymethyl cellulose or both, which remain effective in prov:iding the astringent properties of zinc and the anti-caries properties of fluoride. In particular, gel-type dentifrices providing both zinc astringency with or without a fluoride anti-caries effect have not been satisfactorily available due to the incompatibility of zinc ion with monofluorophosphate and with alkali metal carboxymethyl cellulose in the presence of various siliceous polishing agents.
In the present invention, use is made of a precipitated, amorphous silica gel which has been described in British Published Patent Application No. 2 038 303 A to Feig et al and in U.S.
Patent No. 4,528,181 granted July 9, 1985. In U.S. Patent No.
4,528,181, a dentifr:ice contain:ing the precipitated, amorphous silica gel is described in which a dual source o~ fluoride containing sodium fluoride and sodium monofluorophosphate and a source of calcium is stabilized by an alkali metal phytate to improve fluoride retention.
Such precipitated, amorphous silica gel material is available from Grace G.m.b.H. as product such as Syloblanc 81, Syloblanc 81C and Syloblanc 82. It is distinct from the types of xerogel which have been sold by W R. Grace and Co. under the trademark Syloid and which are particularly described in U.S. Patent 3,538,230 to Pader et al. Indeed, although some products sold by Grace G.m.b.H. under the trademark Syloblanc were formerly or are still available under the trademark Syloid, none of Syloblanc 81, Syloblanc 81C or Syloblanc 82 had ever been available under the trademark Syloid. It is particularly noteworthy that the grades of the silica gel employed in the present invention are less abrasive as the surface area increases whereas the grades of silica xerogel which are described in U.S.
Patent 3,538,230 are generally more abrasive as their surface area increases.
In view of the low compatibility of most polishing agents with zinc including those polishing agents of U.S. Patent No. 3,538,230, it was quite unexpected that a particular siliceous polishing material would not have such a problem and that further, in the presence of such polishing agent, the reaction between zinc ions and alkali metal carboxymethyl cellulose is substantially reduced. Furthermore, it was unexpected, that in the presence of such particular siliceous polishing material and æinc ions, alkali metal monofluorophosphate remains stable and compatible to provide fluoride. Nevertheless, in accordance with the present invention, it has been found that retention of high levels of astringency from zinc ions is attained when such particular siliceous polishing material is employed, whether or not alkali metal carboxymethyl cellulose is also employed, or monofluorophosphate is employed to give high levels of fluoride ions which are also retained.
It is an advantage of this invention that an astringent dentifrice c~ontaining zinc ions is provided, which may effectively contain monofluorophosphate or an alkali metal carboxymethyl cellulose gelling agent or both.

1%f;~839 ;l It is a further advantage of this invention that an astringent gel-type toothpaste containing zinc ions is provided, which may optionally contain monofluorophosphate or an alkali metal carboxymethyl cellulose gelling agent or both.
Further advantages of the invention will be apparent from consideration of the following specification.
~ n accordance with certaln of its aspects, this invention relates t:o an astringent dentifrice comprising about 20-90% by ¦ weight of liquid vehicle comprising water in amount of at least ¦¦ about 3% by weight of said dentifrice, about 0.05-5% by weight of a gelling agent and about 10-50% by weight of a polishing agent comprising a synthetic precipitated, amorphous silica gel having an average particle size of 1 to 30 microns and a) a surface area of 1 to 600 m2/g, b) a pore volume of 0.05 to 0.5 cm /g, I c) a product of surface area (in m2/g) by pore volume (in cm3/g) less than or equal to 240, ¦ d) a calculated pore diameter of 1.5 to 2.5 nm, and e) a water content of less than 25% by weight;
and up to about 5% of a water-soluble zinc salt which provides at least about 50 ppm of zinc ions to said dentifrice. Furthermore said dentifrice may contain an alkali metal carboxymethyl cellulose as the gelling agent and/or may contain an alkali metal monoEluorophosphate in amount to provide about 0.01-1% fiuoride.

12~i0~339 1~

As indicated above, the synthetic precipitated silica is of the type described in British Published Patent Application

2 038 303 A and U.S. Patent No. 4,528,181. Specific grades of the silica material described therein are suitable for use in the practice of the present invention. Further, specific grades which are particularly preferred are described l in an October, 1980, trade publication of Grace G.m.b.H. of ¦I Norder!~tadt, Germany, as Syloblanc 81 and Syloblanc 82 as have l the foLlowing typical physical and chemical charactertistics:

, SYLOBLANC 81 SYLOBLANC 82 1, Average particle size ,l (according to Coulter) um 4 7 Wet screen residue (42 um) % 0.02 0.02 pH (5% suspension in water) 3 6 l~ Surface area (B.E.T.)m2/g 400 480 ~l Loss on drying % 7 4 ¦I SiO2 content (on ignited , substance) % 96 99 1 Refractive index 1.46 1.46 l, In a variation of Syloblanc 81 available as Syloblanc 81C, the 1I pH (5% suspension in water) is about 6-8.
1~ Syloblanc 81 and 81C, in particular, are highly effective in polishing dental surfaces. Syloblanc 82 is lower in polishing etEect bu an be useù by consumers desiring such reduced effect.
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IZ6~ 9 Likewise, grades of the silica material may be proportioned in mixtures to ~produce appropriate polishing characteristics. It is noteworthy that the dentifrices are compatible in unlined aluminum dentifrice tubes even in the absence of phytate salt, which is necessary in the invention described in U.S. Patent No. 4,528,181. The precipitated amorphous silica gel is employed in amount of about 10-50% by weight, typically about 10-40% in a gel dentifrice.
Aqueous slurries of the silica materials (e.g. about 5 to 20~ slurries) typically have a pH of about 2 to 9. Since the dentifrice composition of the present invention preferably has a pH (measured in 10% aqueous slurry) of at least about 5.5, e.g.
about 5~5-7.5, the pll of the dentifrice may be adjusted with an appropriate material such as sodium hydroxide, etc.
l'he water-soluble zinc salt is present in the dentifrice in amount of up to about 5% by weight, preferably above 0.01-3%
I and most preferably about 0.1-2%. Water--soluble zinc salts in accordance with the present in-rention are at least about 10%
by weight, preferably at least 20%, soluble in water. There is provided at least about 50 ppm of zinc ions to the dentifrice, preferably at least about 750 ppm and most preferably at least about 1000 ppm of zinc ions. Suitable zinc salts include zinc sulphate, zinc chloride, zinc bromide, zinc iodide, zinc ; nitrate and zinc acetate. In tlle case of the zinc chloride, ~6~39 i~ - 8 -!~
0.01% by weight provides about 50 ppm of zinc ions and 0.2% by weight provides about 1000 ppm of zinc ions. 0.48% by weight of ~inc sulphate heptahydrate provides about 1000 ppm of zinc ions. In addition, zinc oxide, a sparingly soluble (below 0.0005~) zinc compound may also be added to prevent a lowering of the pH in the product. This acts as a buffer system and improves p~l stability and compatibility in unlined aluminum tubes.
It may be present in amount of about 0.005-0.5% by weight.
The dentifrice comprises a liquid vehicle containing about

3-60% by weight of water, typically mixed with at least one humectant. The liquid phase comprises about 20-90% by weight of the dentifrice and is generally about 25-80% liquid, typically with about 3-50% by weight, preferably about 3-10% of water in a substantially clear gel dentifrice or gel dentifrice which would be substantially clear except for the presence of an opacifying agent, such as titanium dioxide, and about 11-50% of water in a hazy to opaque gel dentifrice with about 10-90% by weight, preferably about 15-80%, of humectant. Typical humectants include glycerine, sorbitol (e.g. 70% solution), maltitol, polyethylene glycol of molecular weight of about 400-600, propylene glycol and mixtures thereof.
The dentifrice also contains a gelling or binding agent as a solid ve~hicle agent, although this may be in small amount, since the synthe!tic, precipitated silica can effect a thickening or gelling of the dentifrice into a creamy or pasty consistency.

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_ 9 _ Alkali metal carboxymethyl cellulose is preferred in accordance with an aspect of this invention, but other gelling or binding agents that may be present include hydroxyethyl cellulose, hydroxypropyl cellulose, xanthan, Irish moss, iota-carrageenan, gum tragacanth, polyvinyl pyrrolidone, starch and mixtures thereof. Such gelling agents may be used in amount of about 0.05%-5% by weight, typically about 0.05-2%
and preferably about 0.1-1.5%. Particularly desirable is the I use of sodium carboxymethyl cellulose.
¦ Alkali metal, such as sodium monofluorophosphate and ¦ potassium monofluorophosphate is compatible in the dentifrice.
Sodium monofluorophosphate is especially preferred. In the past, j~ when it has been attempted to formulate a dentifrice with liquid ¦ vehic:le, gelling agent, polishing agent, zinc salt and sodium I monofluorophosphate, substantial levels of zinc ions and fluoride ¦l ions have been lost by insolubilisation. Unexpectedly, when the i polishing agent is the defined synthetic, precipitated, amorphous silica gel, high levels of fluoride ions and substantial l retention of zinc ions are attached. Such high levels of fluoride I I retention is not attained when simple fluoride such as sodium fluoride is employed.
Sodium monofluorophosphate, Na2P03F, as commercially available, may vary considerably in purity. It may be used in any suitable purity provided tllat any impurities do not substantially adversely affect the desired properties. In general, l:he purity is desirably at least 80%, and preferably ~Z60~3~

_ 10 --at least 90% by weight of sodium monofluorophosphate with the balance being primarily impurities or by-products of manufacture such as sodium fluoride and water-soluble sodium phosphate salt.
Expressed in another way, the sodium monofluorophosphate employed should have a total fluoride content of above 12%, preferably 12.7%, a content of not more than 1.5%, preferably not more than 1.2%, of free sodium fluoride; and a sodium monofluorophosphate content of at least 12%; preferably at least 12.1% all calculated as fluoride. Alkali metal monofluorophosphate is present in amount to provide fluoride in amount of about 0.01-1% by weight, preferably about 0.1%. Thus, sodium monofluorophosphate can be present in amount of about 0.076-7.6%, preferably 0.76%, which corresponds to about 100-10000 ppm of fluoride, preferably about 1000 ppm.
Any suitable surface active or detersive material may be included in the dentifrice compositions. Such compatible materials are desirable to provide additional detersive foaming and antibacterial properties depending upon the specific type j of surface active material and are selected similarly. These I detergents are water-soluble compound usually, and may be anionic, nonionic, amphoteric or cationic in structure. It is usually preferred to use the water-soluble non-soap or synthetic organic detergents.~ Suitable detersive materials are known and include, for example, the water-soluble salts of higher fatty acid and moDog1yceride monosulph-te deterp,ent ~e.g. sodium coconut fatty !l li lZ1~0839 acid monoglyceride monosulphate), higher alkyl sulphate (e.g.
sodlum lauryl sulphate), alkyl aryl sulphonate (e.g. sodium dodecyl benzene sulphonate, higher fatty acid esters of 1,2-dihydroxy propane sulphonate) and the like.
Further surface active agents include the substantially saturated higher aliphatic acyl amides of lower aliphatic amino carboxylic acid compounds, such as those having 12 to 16 carbons in the acyl radical. The amino acid portion is derived generally from the lower aliphatic saturated monoaminocarboxylic acid compounds. Suitable compounds are the fatty acid amides of glycine, sarcosine, alanine, 3-aminopropanoic acid and valine having about 12 to 16 carbons in the acyl group. It is preferred to use the N-lauroyl, myristoyl and palmitoyl sarcoside compounds, however, for optimum effects.
The amide compounds may be employed in the form of the free acid or preferably as the water-soluble salts thereof, such as the alkali metal, ammonium, amine and alkylolamine salts.
Specific examples thereof are the sodium and potassium N-lauroyl, myristoyl and palmitoyl sarcosides, ammonium and ethanolamine N-lauroyl glycide and alanine. For convenience herein, reference to "amino carboxylic acid compound," "sarcoside," and the like refers to such compounds having a free carboxylic group or the water-soluble carboxylate salts.
Such materials are utilized in pure or substantially pure form. They should be as free as practicable from soap or similar .' 3~

higher fatty acid material which tends to reduce the activity of these compounds. In usual practice, the amount of such higher fatty acid material is less than 15% by weight of the amide and insufficient to adversely affect it, and preferably less than about 10% of said amide material.
Other particularly suitable surface-active materials include nonlonic agents such as condensates of sorbitan monostearate with approximately 20 moles of ethylene oxide, condensates of ethylene oxide with propylene oxide, condensates of propylene glycol ("Pluronic" materials) and amphoteric agents such as long chain (alkyl) amide-alkylene-alkalated amine derivatives, which are available under the trademark "Miranol" C2M. Cationic surface active germicides and antibacterial compounds such as diisobutyl-pheno~yethyoxyethyl dimethyl benæyl ammonium chloride, benzyl dimethyL stearyl ammonium chloride, tertiary amines having one fatty alkyl group tof from 12-18 carbon atoms) and two (poly) oxyethylene groups attached to the nitrogen (typically containing a total of from about 2 to 50 ethanoxy groups per molecule) and salts thereof with acids, and compounds of the structure (CH2CH20)XH ~ CH2cH20)xH
R N CH2cH2cH2 ~
~ (CH2CH20)y~ !
wherein R represents a fatty alkyl group containg from about 12 !!
to 18 carb~in atoms, and x, y and 2 total 3 or higher, as well as salts thereof with mineral or organic acids, may also be used.

It is preferred to use from about 0.05 to 5% by weight of the ; ~I foregolng surface-active materials in the oral preparation of ~ present invention.

~;~6~839 Var-ious other materials may be incorporated in the dental creams of this invention. Examples thereof are opacifiers, preservatives, stabilizers, silicones, chlorophyll compounds and ammoniated materials such as urea, diammonium phosphate and mixtures thereof. These adjuvants are incorporated in the instant compositions in amounts which do not substantially adversely affect the desired properties and characteristics and are suitably selected and used in conventional amounts.
For some purposes it may be desirable to include antibacterial agents in the compositions of the present invention.
Typical antibacterial agents which may be used in amount of about 0.01% to about 5%, preferably about 0.05 to about 1.0%, by weight of the dentifrice composition include cetyl pyridinium chloride, benzethonium chloride as well as:
Nl-4 (chlorobenzyl) -N5- (2,4-dichlorobenzyl) biguanide p-chlorophenyl biguanide;

4-chlorobenzhydryl biguanide;
4-chlorobenzhydrylgu~nylurlea;
N-3-lauroxypropyl-N5-p-chlorobenzylbiguanide;
1,6-di-p-chlorophenylbiguanidohexane;
l-(lauryldimethylammonium)-8-(p-chlorobenzyldimethyl-ammonium) 5,6-dichloro-2-guanidinobenzimidazole;
Nl-p-chlorophenyl-N5-laurylbiguanide;
; ' 5-amin~o-1,3-bis (2-ethylhexyl)-5-methylhexahydropyrimidine;
and their non-toxic addition saIts.

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1~6Q~13~

Any suitable flavoring or sweetening materials may be employed in formulating a flavor for the compositions of the present invention. Examples of suitable flavoring constituents include the flavoring oils, e.g. oils of spearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus, marjoram, clnnamon, lemon and orange, as well as methyl salicylate.
SuitabLe sweetening agents include sucrose, lactose, maltose, sorbitol, sodium cyclamate, sodium saccharine, dipeptides of U.S.
Patent 3,939,261 and oxathia~in salts of U.S. Patent 3,932,606.
Suitable flavor and sweetening agents may together comprise from about 0.01 to 5% or more of the composition.
i~ The dentifrice is packaged in a container from which it can be readily extruded such as a pressure differential or mechanically operated dental cream dispenser or a lined or unlined il aluminum tube or wax lined lead tube or plast-lc tube, which may I be laminated with aluminum. The rheological properties are highly ; ~I desirable when a mechanically operated dispensing container of the type described in British Patent Application 2,070,695A, published September 9, 1981, is employecl. This dispensing container comprises a dispensing mouthpiece, a tension member, a central rod, a piston and operating hand control.
Pressure differential dispensing container may be of the aerosol o~ vacuum type. Suitable pressure differential dispensers ~z~

include those comprising a collapsible product-containing bag being ciisposecl within a rigid container which contains a propellant fluid. In such dispensing containers, operation of the valve permits release of the product only, the propellant fluid being separated from the product by the fluid impermeable bag. Dispensers of this type are described in U.S. Patents ~I 3,828,977 and 3,838,796. These are the so-called Sepro~
dispensers. So-called Exxel and Enviro Spray containers also utilize pressure.
Still another type dispenser is the barrier piston container described in U.S. 4,171,757. Such container includes a valve, a product-containing compartment and an essentially fluid-tight barrier piston which separates the propellant fluid from the contained product (the so-called Diamond container).
The dentifrice is typically prepared by forming a premix of the gelling agent with the liquid vehicle components, e.g.
water and humectant, which may also contain additional ingredients such as the monofluorophosphate and/or sweetener, and blending therewith the synthetic precipitated silica gel and ~inc salt. Additional employed ingredients may then be added.
Although the invention is described with regard to the i illustrative examples, it will be apparent to one skilled in the art that various modifications may be made thereto which fall within its scope. All amounts are by weight unless , otherwise :indicated.

Il .

~0~39 The following opacified gel dentifrices are prepared and placed in unlined aluminum tubes:
PARTS
_A B

Glycerine 25.00D 25.000 Sorbitol (70%) 47.050 43.830 Xanthan 0.260 0.260 Sod:Lum saccharin 0.170 0.170 Titanium tlioxide 1.000 1.000 Water 3.000 3.000 Zinc sulphate heptahydrate 0.480 0.480 Precipitated amorphous silica gel* 20.000 Silica xerogel*t~ - 17.000 Silica aerogel*** - 6.500 Sodium hydroxide (40%) 0.280 Sodium lauryl sulphate 1.760 1.760 Flavor 1.000 1.000 pH (20% slurry) 5.9 6.1 *Syloblanc 81 available from Grace G.m.b.H.;
**Syloid ALl available from Grace G.m.b.H., formerly known as Syloid 63;
***Syloid 244 thickener available from W. R. Grace & Co.
The th~oretical amount of soluble zinc ions in each gel ¦, dentifrice is 1000 ppm or 0.100%.
. ~i .

Ij !

~6~8;~9 Dentifrice A does not require the presence of thickener material to provide desirable gel character. Its consistency is about equivalent to that of dentifrice B.
E,ach dentifrice is aged at room temperature and at 43C.
Both retain generally equivalent desirable consistencies. The percentage amounts of available soluble zinc ions in each dentifrice is determined to be as follows:
% Zn+2-Room Temperature l 3 Initial ~onth Months Weeks Month Months Dentifrice A 0.084 0.080 0.050 0.091 0.070 0.050 Dentifrice B 0.054 0.042 0.005 0.049 0.048 0.005 Dentifrice A containing Syloblanc 81 retains superior levels of soluble zinc ions compared to the otherwise generally equivalent Dentifrice B containing Syloblanc ALl.
Similar superior levels of retention of soluble zinc ions are a-tt~ined when Syloblanc 81 of the dentifrice A is replaced with Syloblanc 82 and with a 1:1 mixture of Syloblanc 81 and 82, in each, with levels of sodium hydroxide reduced or omitted, with their amounts added to sorbitol (70%).
Likewise, superior retention levels of soluble zinc ions are attained when Syloblanc 81 is replaced with Syloblanc 81C, with sodium hydroxide omitted and its amount added to sorbitol (70~)-0.25 parts of zinc oxide are incorporated into each ofdentfifrices A and B, in place of corresponding amounts of sorbitol, ~thereby stabilizing the pH during aging and improving compatibility with unlined aluminum tubes for prolonged periods.

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~¦ EXAMPLE 2 The following opacified gel dentifrices are prepared and placed in unlined aluminum tubes:

PARTS
l A B
! Glycerine 25.000 25.000 ¦ Sorbitol (70%) 47,050 43 550 Sodium carboxymethyl ! cellulose 0.260 0.260 Sodium saccharin 0.170 0.170 , Ti~anium dioxide 1.000 1.000 il~ Water 3.000 3.000 Zinc sulphate heptahydrate 0.480 0.480 Precipitated amorphous si:Lica gel~ 20.000 Silica xerogel~* - 17.000 Silica aerogel*** - 6.500 'I Sodium hydroxide (40%) 0.280 0.280 ~¦ Sodium lauryl sulphate 1.760 1.760 Flavor 1.000 1.000 ¦ pH (20% slurry) 5.9 6.1 *; **; *** - See Example 1.

The theoretical amount of soluble zinc ions in each gel dentifrice is lO00 ppm or 0.100%.
Dentifrice A does not require the presence of thickener material to provide desirable gel character initially.
Each dentifrice is aged at room temperature and at 43C.
Both generally retain equivalent desirable consistencies. The percentage amounts of available soluble zinc ions in each dentifrice is determined to be as follows:
% Zn~2-Room Temperature 43C
Initial Month Months Weeks Month Months Dentifrice A 0.080 0.079 0.050 0.082 0.069 0.050 Dentifrice B 0.052 0.039 0.002 0.050 0.060 0.002 Dentifrice A containing Syloblanc 81 retains gel character and superior levels of soluble zinc ions compared to the otherwise generally equivalent dentifrice B containing Syloblanc 63. When the conventional 7 MXF grade of sodium carboxymethyl cellulose is employed there is phase separation and breakdown in the presence of Syloid 63 polishing agent which does not occur as much when Syloblanc 81 is employed.
It is noted that the two-week and one-month Dentifrice B
evaluation levels at 43C reflect routine experimental variations.
Similar superior levels of retention of soluble zinc ions are attained when Syloblanc 81 of dentifrice A is replaced with Syloblanc 82 and with a 1:1 mixture of Syloblanc 81 and 82, in each, with levels of sodium hydroxide reduced, or omitted with their amounts added to sorbitol (70~). j ~26~8~9 ¦ Likewise, superior retention levels of soluble ~inc ions are attained when Syloblanc 81 is replaced with Syloblanc 81C, with sodium hydroxide omitted and its amount added to sorbitol (70%).
0.25 parts of zinc oxide are incorporated into each of dentlfrices A and B, in place o~ corresponding amounts of sorbitol, thereby stabilizing the p}l during aging and improving compati.bility with unlined aluminum tubes for prolonged ! periods.

l¦ The following opacified gel dentifrices are prepared and jj placed in unlined aluminum tubes:
; PARTS
A B
j Glycerine 25.000 25.000 . Sorbitol (70%) 46.340 46.880 Sodium carboxymethyl cel.lulose O.l90 0.190 Sodium saccharin 0.170 0.170 Titanium dioxide 1.000 1.000 Water 3.000 3.000 Zinc sulphate heptahydrate 0.480 0.480 Sodium monofluorophosphate 0.760 ; Sodium fluoride - 0.220 Precipitated amorphous silica ~3el* 20.000 20.000 Sodium hydroxide (40%) 0.300 0.300 Sodium lauryl sulphate l.760 1.760 Flavor . 1.000 1.000 ph (20% slurry) 6.0 5.9 ; * - See Example 1.

3~

The theoretical amounts of soluble zinc ions and fluoride in each gel dentifrice is lOOO ppm or 0.100%, for each of the zinc ions and fluoride.
Each dentifrice is aged at room temperature and at 43C.
The percentage amounts of available soluble zinc ions and of fluoride in each dentifrice is determined to be as follows at room temperature:

% Zn~2; % Monofluorophosphate as Fluoride (Dentifrice A);
% Fluoride (Denti~rice B) Room Temperature Initial One Month Dentifrice A 0.66 Zn 0.066 Zn 0.096 F 0.097 F
Dentifrice B 0.070 Zn 0.051 Zn 0.100 F 0.048 F
Dentifrice A containing sodium monofluorophosphate provides substantial retention of both zinc ions and fluoride compared to dent:ifrice B containing sodium fluoride. At 43C, gas forms in the unlined aluminum tube containing dentifrice B, while the unlined aluminum tube containing dentifrice A remains stable.
Zinc ion and fluoride retention are low when the xerogel Syloid 63 available from W. R. Grace & Co. replaces Syloblanc 81.
; Similar results to those determined with dentifrice A are attained when potassium monofluorophosphate replaces sodium monofluorophosphate.

., ~26~39 Similar superior levels of retention of soluble zinc ions and fluoride are attained when Syloblanc 81 of dentifrice A is replaced with Syloblanc 82 and with a 1:1 mixture of Syloblanc 81 and 82, in each, with levels of sodium hydroxide is reduced or omitted with their amounts added to sorbitol (70%).
Likewise, superior retention levels of soluble zinc ions and fluoride are atained when Syloblanc 81 is replaced with Syloblanc 81C, with sodium hydroxide omitted and its amount added to sorbit:ol (70%), 0.2'i parts of zinc oxide are incorporated into each of dentifrices A and B, in place of corresponding amounts of sorbitol, thereby stabilizing the pH during aging and improving compatibility with unlined aluminum tubes for prolonged periods.

The following stable visually clear gel dentifrices are prepared ancl placed in unlined aluminum tubes:
PARTS
A B C D
Glycerine 25.000 25.00025.000 25.000 Sorbitol (70%) 48.310 48.59048.590 48.450 Xanthan 0.260 0.260 0.260 0.260 Sodium saccharin 0.170 0.170 0.170 0.170 Water 3-000 3.000 3-000 3.000 Zinc chloride 0.020 0.020 0.020 0.020 Syloblanc 81 20.000 - - 10.000 Syloblanc 81C - 20.000 Syloblanc 82 - - 20.000 10.000 Sodium hydroxide (40%)0.280 - - 0.140 Sodium lauryl sulphate1.760 1.760 l.760 1.760 Flavor 1.000 1.000 1.000 1.000 Blue color solution (Ig) 0.200 0.200 0.200 0.200 I

~26083~
i Il The following stable visually clear gel dentiErices are prepared and placed in unlined a:l.uminum tubes:
PARTS
A B C D
Glycerine 25.00025.000 25.000 25.000 Sorbitol (70%) 48.31048.590 48.590 48.450 Sodium carboxymethyl ce:l.lulose 0,260 0.260 0.260 0.260 Sodium ;saccharin 0.170 0.170 0.170 0.170 Water 3.000 3.000 3.000 3.000 Zinc chloride 0.020 0.020 0.020 0.020 Syloblanc 81 20.000 - - 10.000 Syloblanc 81C - 20.000 Syloblanc 82 - - 20.000 10.000 Sodium hydroxide (40%)0.280 - - 0.140 Sodium lauryl sulphate1.7601.760 1.760 1.760 Flavor 1.000 1.000 1.000 1.000 Blue color solution (1%) 0.200 0.200 0.200 0.200 Similar stability is attained when potassium carboxymethyl . cellulose replaces sodium carboxymethyl cellulose.

;:

~;:60133~

¦The following stable visually clear gel dentifrices are prepared and placed in unlined aluminum tubes: !

I PARTS
¦ A B C D
Glycerine 25.000 25.000 25.000 25.000 Sorbitol (70%) 47.550 47.830 47.830 47.690 Xanthan 0.260 0.260 0.260 0.260 Sodium saccharin 0.170 0.170 0.170 0.170 Water 3.000 3.000 3.000 3.000 . Sodium monofluoro-I phosphate 0.760 0.760 0.760 0.760 :' Zinc chloride 0.020 0.020 0.020 0.020 I Syloblanc 81 20.000 - - lO.000 Syloblanc 81C - 20.000 Sylob:Lanc 82 - - 20.000 10.000 Sodium hydroxide (40%) 0.280 - - 0.140 Sodium lauryl sulphate 1.760 1.760 1.760 1.760 Flavor l.000 1.000 1.000 l.000 Blue color solution (1%) 0.200 0.200 0.200 0.200 ;

The following ha~y and opaque gel dentifrices are prepared and packaged in mechanically operated dispensing containers:

I PARTS
A B C D
Glycerine 25.000 25.00025.C00 25.000 Sorbitol (70%) 24.970 24.870 24.870 24.870 Iota carrageenan 0.700 0.700 0.700 0.700 ¦I Sodium saccharin 0.170 0.170 0.170 0.170 j Water 25.000 25.00025.000 25.000 ll Zinc bromide dihydrate 0.400 - - -.1, Zinc iodide - 0,500 " Zinc nitrate hexahydrate - - 0.500 Zinc acetate dihydrate - - - 0.500 Syloblanc 81C 21.000 21.000 21.000 21.000 Sodium lauryl sulphate 1.7601.760 1.760 1.760 Flavor 1.000 1.0001.000 1.000 ¦l In the examples sodium cyclamate may replaced sodium sacch~rin.

~26(~83~

The following stable hazy and opaque gel dentifrices are prepared and placed in unlined aluminum tubes:
PARTS
-A B C D
Glycerine 25.000 25.000 25.000 25.000 Sorbiltol (70%~ 24.970 24.870 24.870 24.870 Sodlum carboxymethyl cellulose 0.700 0.700 0.700 0.700 Sodium saccharin 0.170 0.170 0.170 0.170 Water 25.000 25.000 25.000 25.000 Zinc bromide dihydrate 0.400 Zinc iodide - 0.500 Zinc nitrate hexahydrate - - 0.500 Zinc acetate dihydrate - - - 0.500 Syloblanc 81C 21.000 21.000 21.000 21.000 Sodium lauryl sulphate 1.760 1.760 1.760 1.760 Flavor 1.000 1.000 1.000 1.000 In the examples sodium cyclamate may replace sodium saccharin.

I

;~
~

~Z6~383~

The following stable hazy and opaque gel dentifrices are prepared and packaged in mechanically operated dispensing containers:
PARTS
A B C D
Glycerine 25.000 25.000 25.000 25.000 Sorbitol (70%) 24.210 24.110 24.110 24.110 Iota carrageenan 0.700 0.700 0.700 0.700 Sodium saccharin 0.170 0.170 0.170 0.170 Water 25.000 25.000 25.000 25.000 Sodium monofluoro-phosphate 0.760 0.760 0.760 0.760 Zinc bromide dihydrate 0.400 - - -Zinc iodide - 0,500 Zinc nitrate hexahydrate - - 0.500 Zinc acetate dihydrate - - - 0.500 Syloblanc 81C 21.000 21.000 21.000 21.000 Sodium lauryl sulphate 1.760 1.760 1.760 1.760 Flavor 1.000 1.000 1.000 1.000 In the examples, sodium cyclamate may replace sodium saccharin.
~ It will be apparent to those skilled in the art that further ;i modifications of the examples illustrat:ive of the invention may be made thereto.

i ' 1!

Claims (20)

THE EMBODIEMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An astringent dentifrice comprising about 20-90% by weight of liquid vehicle comprising water in amount of at least about 3%
by weight of said dentifrice, about 0.5-5% by weight of a gelling agent and about 10-50% by weight of a polishing agent comprising a synthetic precipitated, amorphous silica gel having an average particle size of 1 to 30 microns and a) a surface area of 1 to 600m2/g, b) a pore volume of 0.05 to 0.5 cm3/g, c) a product of surface area (in m2/g) x pore volume (in cm3/g) less than or equal to 240, d) a calculated pore diameter of 1.5 to 2. 5 nm and e) a water content of less than 25% by weight;
and with up to about 5% of a water-soluble zinc salt which provides at, least about 50 ppm of zinc ions to said dentifrice.

2. The astringent dentifrice claimed in Claim 1 wherein said gelling agent is an alkali metal carboxymethyl cellulose gelling agent.

3. The astringent dentifrice claimed in Claim 1 which further contains an alkali metal monofluorophosphate in an amount which provides about 0.01-1% fluoride ions.

4. The astringent dentifrice claimed in any of Claim 1, Claim 2 or Claim 3 wherein said zinc salt is present in amount of 0.01-3% by weight.

5. The astringent dentifrice claimed in any of Claim 1, Claim 2 or Claim 3 wherein said zinc salt is selected from the group consisting of zinc sulphate, zinc chloride, zinc bromide, zinc iodide, zinc nitrate and zinc acetate.

6. The astringent dentifrice claimed in Claim 1, Claim 2 or Claim 3 wherein said zinc salt is zinc sulphate heptahydrate.

7. The astringent dentifrice claimed in Claim 1, Claim 2 or Claim 3 wherein said zinc salt is zinc chloride.

8. The astringent dentifrice claimed in Claim 1 wherein said water in said liquid vehicle comprises about 3-10% by weight of said dentifrice and said synthetic amorphous silica gel comprises about 10-40% by weight of said dentifrice.

9. The astringent dentifrice claimed in Claim 1 wherein said water in said liquid vehicle comprises about 11-50% by weight of said dentifrice.

10. The astringent dentifrice claimed in Claim 1 wherein said synthe-tic amorphous silica gel is at least one of the synthetic amorphous silica gels having the further characteristics of:

11. The astringent gel dentifrice claimed in any of Claim 1, Claim 2, or Claim 3 wherein said gelling agent is sodium carboxymethyl cellulose.

12. The astringent gel dentifrice claimed in Claim 1, Claim 2 or Claim 3 wherein said gelling agent is sodium carboxymethyl cellulose and said zinc salt is present in an amount of 0.01-3% by weight.

13. The astringent gel dentifrice claimed in Claim l, Claim 2 or Claim 3 wherein said gelling agent is sodium carboxymethyl cellulose and said zinc salt is selected from the group consisting of zinc sulphate, zinc chloride, zinc bromide, zinc iodide, zinc nitrate and zinc acetate.

14. The astringent dentifrice claimed in Claim 3, wherein said alkali metal monofluorophosphate is sodium monofluorophosphate.

15. The astringent dentifrice claimed in Claim 14 wherein said zinc salt is present in an amount of 0.01-3% by weight.

16. The astringent dentifrice claimed in Claim 14 wherein said zinc salt is selected from the group consisting of zinc sulphate, zinc chloride, zinc bromide, zinc iodide, zinc nitrate and zinc acetate.

17. The astringent dentifrice claimed in Claim 3 wherein said water-soluble zinc salt is present in amount which provides about 1000 ppm of zinc ions and said alkali metal monofluorophosphate is present in amount which provides about 1000 ppm of fluoride.

18. The astringent dentifrice claimed in Claim 17 wherein said zinc salt is zinc sulphate heptahydrate and said alkali metal monofluorophosphate is sodium monofluorophosphate.

19. The astringent dentifrice claimed in any of Claim 1, Claim 2 or Claim 3 wherein said dentifrice is packaged in an unlined aluminum tube.

20. The astringent dentifrice claimed in any of Claim 1, Claim 2 or Claim 3 wherein said dentifrice also contains about 0.005-0.5% by weight of zinc oxide.