CA1042804A - Toothpaste - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A dental cream containing calcium carbonate as the principal abrasive and a lesser amount of sodium bicarbonate as an additional abrasive.
The principal abrasive of the toothpaste may also be comprised of a mixture of abrasives such as chalk, silica, alumina, zirconium silicate or sodium alumino-silicate in combination with the minor amount of sodium bicarbonate. The latter may be included in amounts up to about 25%, while the former may be included in amounts up to about 60%. This dental cream, with a major amount of calcium and some sodium bicarbonate, is unexpectedly stable with acid, fluoride and unlined aluminium tubes.

Description

Thi~ invention relates t~ toothpa~tes and more partlcularly to toothpastes containing a~ an ad~unct abrasive, dispersed particles of ~odium bicarbonate. The invention also relates to a dental cream composition suitable for use in an unlined aluminum tube.
Baking soda has been employed in many fields and is a common household ingredient. In past year~, its u~e in dentlfrices, particularly tooth powders, has been proposed but has not received much acceptance generally. The typical dentlfrlce which have had significant consumer acceptance in recent years are toothpastes having a hlgh content of water-insoluble abrasives such as dicalcium phosphAte or other lnsoluble phosphates in an aqueous humectant base.
The development of a practical and effective baking soda-containing toothpaste capable of consumer acceptability presents many special considerations. Among the factors which are to be considered are the unique character of baking soda chemically, physically and cosmetically when consldered and employed as a toothpaste lngredient. For example, it 18 comparatively water-insoluble and tends to release carbon dioxide in an aqueous system, It is extremely salty to the taste which is probably one of the more important factors ln the purchase and use Or a particular product, Other factors in formulation of a suitable product include the over-all cleaning and poli~hing power of the product, its stability and appearance combined with special care in manufacture, etc. l, qF :, In formulating a dentifrice based on precipitated calcium carbonate, the incompatibility of calcium carbonate with acids and most fluoride salts must be taken into account due to the character thereof.
As can be seenJ the problems are thus two fold where a dentifrice includes both baking soda and chalk therein. ~he foregoing is one from among the many difficulties which the instant invention overcomes and obviates.
A further feature of the invention is directed to the packaging of dental creams in unlined aluminum tubes, which is desired in view of the relatively low cost of such tubes and of their light weight. When dental creams are packaged in unlined aluminum containers, it is sometimes found that the containers corrode and/or dental cream formulations become unstable.
The present invention provides a dental cream containing about 25-60% by weight of an aqueous humectant system and dispersed therein (1) about 1-25% by weight of sodium bicarbonate and (2) about 20-50% by weight of a water-insoluble dental abrasive system compatible with said bicarbonate in the dental cream, said water-insoluble dental abrasive material being selected from the group consisting of silica, alumina, silicates and car-bonates non-reactive with the bicarbonate; the amount of said component ~2) being greater than the amount of said component (1).
In another aspect, the invention provides a method of making the dental cream hereinbefore defined, which method comprises admixing the glycerine and water of said medium with flavor and said sulfate and there-after adding thereto said sarcosinate and components ~1) and (2).

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In that embodiment of the invention where the dental cream is packaged in unlined alum~num tubes and wherein there 18 additionally present alumina as an abra~ire the inclusion of about 0 05 - 0.25% of dissolved or dispersed silicate is advantageous in order to render the dental cre~m more compatible with an unlined aluminum container. Further-more, calcium carbonate acts to stabilize the composition ,~
with consequent retention of active fluoride. Dental cream compositions containing calcium carbonate have added effec-tiveness in connection with stain removal from teeth.
Calcium carbonate in the form of chalk may be used.
Chalk in the form of a powder having a particle size of il between 1 and 10 microns is preferred. It is also preferred to use a grade of calcium carbonate of moderate apparent specific gravity, e.g., about 0.7 to 0.9. I~ desired~
calcium carbonate grade~ of higher apparent speclfic gravity, e.g., 1.19 to 1.29 may be used. "Apparent specific gravity"
refers to the untamped specific gravity of the calcium 1l carbonate. Calcium carbonate, particularly in the form of !
cO chsllc, often contains ms~neslum carbonate as an impurity. Calcium carbonate containing even small quantlties of magneslum carbonate, e.g. about 0.1 - 0.3%, tends to adversely af~ect the stability of a ~luoride cream wlth consequent loss of active fluori~e. The stable dental cream~ o~
the present invention tolerate small amounts o~ impur~ty, e.g., magnesium carbonate in amounts less than about 1%. However, it : 18 pre~erred that the magnesium carbonate should be about 0.1-0.5 based on the calcium carbonate, especially when ~luoride is present Furthermore, the presence of magnesium carbonate impurity in calclum carbonate or chalk tends to adversely a~fect the compatlbility of the dental cream with unlined aluminum surface8 in whlch it may be packaged. When magnesium carbonate impurity ls present in amountsof at least about 0.1% of the total calcium ~¦
carbonate, it is deslrable to include between about 0.025% and .25~ of a dissolved or dispersed slllcate ln the dental cream n order to render it more suitable for compatible use in an unline luminum contalner.
In accordance with various aspects of this invention~
t 18 now possible to prepare a unique baking soda toothpaste or use in aluminum tubes ln accordance with the ~everal mbodlment8 of the invention WhiCh i8 effective in promoting yglene in the oral cavity and capable of consumer desirab1lity r acceptability by the public. Such product wlll have acceptable leaning, pollshlng and other desirable characteristics 80 as have a beneficial effect upon parts of the dentition (which ay include the teeth and its surrounding or ad~acent elements r ~tructure~ including plaque, calculus, ging~va, muCou8 membranes, .
~nll~n, e .). In pnrtlcular it tonds to lenve ~lth the con3umer .
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1042804 ~:
desirable clean mouth or clean mouth-feel effect. The product ~ -can be formulated so it is stable upon aging or storage without significant release of carbon dioxide bubbles or other forms of undesirable separation or reaction. It is possible to produce and maintain, at certain levels of bicarbonate, a substantially dispersed non-crystalline-appearing granulate which is due in ~
part to the substantially homogeneous distribution of macro- ~-scopic crystalline bicarbonate particles or granules in an otherwise smooth, continuous base, or matrix, contributing to appearance, taste, effect and usage by the consumer.
One aspect of the invention relates to a toothpaste containing an abrasive content comprising a major proportion of a water-insoluble dental abrasive material or mixtures thereof and sodium bicarbonate in the dental cream. Thus the tooth-paste contains dispersed abrasive particles, the abrasive being ` ~ -a mixture of, for example, calcium carbonate, which constitutes the major proportion of the abrasive by weight and preferably makes up about 20 to 60% of the toothpaste, and a lesser amount of sodium bicarbonate. The water-insoluble dental abrasive may be chalk, silica, alumina, zirconium silicate, sodium alumino-silicate, or other compatible silicate or carbonate which is non-reactive with the bicarbonate, or a mixture of two or more of such water-insoluble abrasives. Advantageously, the amount of water-insoluble abrasive is over 20% at preferably at least about 25% of the toothpaste, ordinarily about 25-50%, more pre-ferably about 25-35%.
Although the sodium bicarbonate particles are relative-ly soft as compared to most conventional abrasive particles used ;
in toothpastes they do exert a mechanical cleaning effect on the . . ~: ' ", ;
_ 5 _ teeth. For instance, in a radioactive dentin abrasion (RDA) test a toothpaste containing about 50% of bicarbonate of soda, as the sole abrasive, may show an RDA value of about 100 whereas when the abrasive-free vehicle of that toothpaste is tested similarly the RDA value is only in the neighborhood of 50.
The toothpastes of this invention preferably contain 1% up to about 25%, more preferably about 10-20%, sodium bicar-bonate. The particle size of the sodium bicarbonate particles may vary; it is preferred that they be largely below 0.40 mm in o diameter, with a major proportion by weight being above 0.01 mm in diameter. The vehicle in which the sodium bicarbonate particles are dispersed is preferably aqueous, but its amount and character are preferably such that the sodium bicarbonate is primarily in the undissolved solid state in the toothpaste. It will be under-stood, however, that when the teeth are brushed the sodium bicarbonate particles will tend to dissolve in the saliva.
In one particularly preferred form of the invention the water-insoluble principal abrasive is chalk. It is found that this ingredient greatly improves the cleaning power of the sodium bicarbonate. In additionJ the presence of the chalk appears to promote an improvement in the stability of the tooth-paste on aging at 01evated temperatures such as a decrease in the tendency for essential oils used as flavors, to separate from the toothpaste on aging at 110 or 120F, e.g. when the particles of sodium bicarbonate are of relatively large size, e.g., over 150 microns in diameter.
The combination of the compatible water-insoluble ~ -abrasives such as chalk, silica, alumina, zirconium silicate, and -~
the like, or mixtures thereof is found to yield a sodium bicarbonate '-: , ':
: ' ' ' ' containing toothpaste which has improved cleaning power combined with resistance to flavor separation and which does not tend to form gas on storage. In contrast, when such common dental abrasives as dicalcium phosphate or insoluble sodium metaphosphate are added ts the sodium bicarbonate toothpaste considerable quantities of gas maybe formed even on short term storage (e.g.
at 120P), that is, when included in sufficient quantity.
The average particle size of the chalk is preferably less than 20 microns, most preferably below 10 microns and above -1 micron as earlier stated. Tables I and II below show the particle size ranges and densities of various grades of chalk that may be employed herein. ~-~

TABLE I i~
Sturge Precipitated Calcium ~ ; -Carbonates Particle size, a diameter (u) Apparent density Grade 0-3 3-6 6-10Over 10 (g/ml) Light 80% 14% 4% 2% 0.351-0.430 Medium 67 17 12 4 0.500-0.588 Dense 55 21 16 8 0.727-0.851 Extra dense 50 20 20 10 0.870-1.050 aFrom data obtained by microscopic count.
TABLE II

Particle Size Distribution of ;
PreciPitated Chalk (U.S.P.
Weight below indicated size (%) Grade ;
Diameter (~) Heavy Medium Light Extra light 10.0 85.3 97.7 98.6 98.8 7.5 66.4 92.9 96~8 98.8 5.0 30.6 61.4 85.7 95.6 4.0 14.9 43.7 77.5 93.1 3.0 7.3 32.1 52.1 70.6

2.0 3.6 19.7 20.0 27.7 1 0 2.1 10.1 10.2 10.5 0 5 - 5.1 5.2 5.5 ~ 7 ~

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One particularly suitable alumina is in the form of flat flakes of alpha-alumina crystals, of disk- or plate-like configuration, said flakes having a mean (by weight) particle diameter of less than about 7 microns (e.g. about 2 to 7 microns). The flat alpha-alumina crystals, and a process for preparing them, are described in United States patent

3,121,623. The dentifrice is preferably substantially free of anhydrous alumina particles having diameters above 15 microns and thicknesses above about 2 microns. While it is most preferred to use alumina flakes whose mean particle diameter is less than five microns (e.g. about 3 to 4 microns) it is within the broader scope of this invention to use alumina flakes of larger diameters but similar thickness, such as alumina flakes, described in the aforesaid patent 3,121,623 having average diameters of 9, 12, or 15 or more microns, free of particles over 40 microns in diameter ~preferably free of particles over about 20 microns in diameter) and substantial-ly free of particles having thicknesses above about 3 microns.
In a preferred form of the invention the alpha-alumina flakes are uncoated and free of adhesion to particles of other -materials. It is also within the broader scope of the inven-tion to include other alpha-aluminas, or other abrasives of Mohs hardness above 6, in admixture with the alpha-alumina flakes. For instance, one may replace about one half of the alumina flakes by a pulverized alpha-alumina of irregular shape and having a mean particle size of about 3 to 4 microns ~with all said irregular particles being less than about 7 ~- -microns in their largest dimension); thus, the toothpaste may contain, say 3% of the flakes and 2% of said irregular par- -ticles.

A typical alkali or alkaline earth metal aluminosilicate is a complex having a refractive index of about 1.45, a moisture content of about 5-20% (e.g. 10%) an alumina content of up to about 10% (e.g. 8%) a silica content of at least about 70%, a sodium oxide (or other alkali metal or alkaline earth metal oxide, e.g. calcium oxide) content of up to about 10% (e.g. 7%) and a particle size of below 40 microns, preferably about 1 to 20 `
microns.
Examples of mixtures are blends of chalk and hydrated alumina, in, say, equal amounts, or about 25/75 or about 75/25.
The toothpaste may also contain a small amount of titanium ;
dioxide powder, which has been found to have a marked polishing ~-effect on the teeth when used in the sodium bicarbonate toothpaste.
The weight of titanium dioxide particles in the tooth-paste is generally above about 0.1% of the weight of the toothpaste.
The amount of TiO2 may be included in amounts up to about 6.0%, preferably about 0.2 to 0.6% of the weight of the toothpaste. The particle size of the TiO2 is preferably about 0.1 to 1 micron.
The vehicle of the toothpaste is made up of suitable -liquid preferably containing a thickening agent (e.g. a gelling agent). As indicated the vehicle is preferably aqueous, but it is within the broader scope of the invention to employ non-aqueous vehicles. Generally the liquid will contain a humectant or other viscous water-miscible material such as glycerol, sorbitol, polyethylene glycol, mannitol or mixtures thereof, When water is present it prcferably constitutes about 5 to 35% (e.g. about 10 to 30%) of the total vehicle. Superior results (such as better taste) are obtained when the proportion of water is relatively low, e.g. about 10 to 20% of the total toothpaste, such as when the water to glycerol ratio is in the range of about 0.4:1 to 0.7:1. ;

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lOgZ8Q4 Gelling agents for toothpaste vehicles are well known in the art. These are often high polymers (e.g. gums or other thickening agents) which are soluble or swellable in water or aqueous medium. Sodium carboxymethylcellulose has given excel-lent results. Other materials are gum tragacanth, gum arabic, gum karaya, sodium alginate, hydroxyethyl cellulose, methyl cellulose,ethyl cellulose, carrageen and other polysaccharides, polyvinyl pyrollidones or surh thickening agents as "Veegum"* -(a complex magnesium aluminum silicate2 The amount of thickening agent used in the practice of this invention is preferably sufficient to impart to the mixture the pasty consistency, body and the non-tacky nature which is characteristic of conventional dental creams or toothpastes. As is well known, such dental ~;
creams are extrudable from ordinary collapsible toothpaste tubes to form a ribbon of substantial thickness (e.g. about 3/8 inch) which if left undisturbèd, substantially retains its original thickness over a period of, say, one minute or more (and does not penetrate substantially into the bristles of a toothbrush when resting on the end of such bristles for a similar period); but which preferably offers no substantial resistance to brushing or to deformation when, for instance, one touches it lightly with a finger; and which has little tack, in that lt does not tend to form a string when the finger is pulled away from the ribbon.
The proportion of thickening agent is often within the range of -about 0.5 to 2%, such as about 0.8 to 1.5%, of the toothpaste.
An organic surface active agent is preferably used in the compositions of the present invention to aid in the prophylactic action and in the thorough dispersion of the : . .
*Trade Mark -: '. ~ : , : ' - 10 - ~ ~ .
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,' :' ' ~ ' compositi~n throughout the oral cavity, and to improve cosmetic acceptability and deter~ive and foaming properties. Among the~e are water-soluble salts of the higher alkyl sulfates, such as sodium lauryl sulfate or other suitable alkyl sulfate having 8 to 18 carbon atoms in the alkyl group; water-soluble salts of sulfonQted monoglycerides of higher fatty acid~ such as sodium coconut monoglyceride sulfonate or other suitable sulfonated monoglyceride of a fatty acid of 10 to 18 carbon atoms; salts of amides of higher fatt~ acld (e.g. 12 to 16 carbon atom BCid8) with lower aliphatic amino acids (e.g. taurine or sarcosine) or other amino acid of 2 to o carbon atoms, such as sedium-N-methyl-N-palmitoyl taurlde, sodium N-lauroyl, N-myristoyl or N-palmitoyl sarcosinates; water-soluble salt of the esters of such fatty acids with isethionic acid or with glycerol monosulfate, such as the sodium ~alt of the monosulfated monoglyceride of hydrogenated coconut oil fatty acids; water-soluble salts of olefin sulfonates, e.g. alkene sulfonates or hydroxyalksne sulfonates o~ mixtures thereof having 12 to 18 carbon atoms in the carbon chain of the molecule; water-soluble soaps of higher fatty acids such as those of 12-18 carbon atoms e.g. coconut fatty acids. The cation of the salt may be, for instance, sodium (which is preferred) potassium or mono-di- or triethanolamine. Mixtures of surface-active agents may be used. A particularly ~uitable mixture which provides a high foaming powder with little or no irritating ef~ect comprisea a higher alkyl sulfate and a higher fatty acid sarcosinate, e.g. ln a ratlo of about 1:2 to 2:1, such as about 1:1; instead of all or part of the sarcosinate a higher ~att~
acid monoglyceride sulfonate may be present.

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104Z8~4 Other sultable surface-active materials include nonionic agents such as condensates of sorbitan monostearate with approximately ~0 moles of ethylene oxide, condensates of ethylene oxide with propylene oxide condensates of propylene glycol (available under the trademark "Pluronics") and amphoteric agents ~uch as quaternized imidazole derivatives which are available under the trademark "Miranol" such a~
Miranol C2M. Cationic surface-active germicides and anti-bacterial compounds may also be used. Such compounds include di-l~obutylphenoxyethoxyethyl dimethyl benzyl ammonium chloride, benzyl dimethyl stearyl ammonium chloride, tertiary amines, having one fatty alkyl group (of from 12 to 18 carbon atoms) and two (poly) oxyethylene groups attached to the nitrogen (typically containing a total of from about 2 to 50 ethenoxy groUpB per molecule) and salts thereof with acids, and compounds of the structure:
( CH2CH20 ) ZH ( CH2CH20 ) XH
R-~-c~c~2cH2N----'~''~ (CH2C~2o)yH
where R is a fatty alkyl group consisting from about 12 to 18 carbon atoms, and x~ y and z total 3 or hlgher, as ~ell as salt~
thereof with mineral or organic acids. It is preferred to use from about 0.05 to 5 percent by weight of the foregoing surface-active materials in the instant dentifrice preparations.
The proportion of surface-active agent is preferably ~ithin the range of about 0.05 - 5~ of the toothpaste, more preferably in the range of about 1 to 3~, such as about 1-1/2 to 2%.
In accordance with certain aspects of this invention~
cationic antibacterial agents are included in the compositions of the present invention. Such agents include:

10428~4 ~

Nl-(4-chlorobenzyl)-N5-(2,4-dichlorobenzyl) biguanide;
p-chlorophenyl biguanide;

4-chlorobenzyhydryl biguanide; -4-chlorobenzhydrylguanylurea;
N-3-lauroxpropyl-N5-~-chlorobenzylbiguanide;
l-(lauryldimethylammonium)-8- (p-chlorobenzyldi-methylammonium) octane dichloride;

5 6-dichloro-2-guanidinobenzimidazole;
Nl-p-chlorophenyl-N5-laurylbiguanlde;
5-amlno -1,3-bis (2-ethylhexyl)-5-methylhexahydro-Pyrimidine cetyl pyridinium chloride and their non-toxic acld addltion salts, ~articularly the fluorides and the dlhydrogen fluorides. 1,6-di-(p-chloro~henylbiguanido-hexane) is particularly preferred. Thece agents may be used in amo~unts ranging from about 0.01 to 5 percent by weight of the dentifrice.
Any suitable flavoring or sweetening materials may be employed in formulating a flavor for the compositions of the pre~ent invention. Examples o~ suitable flavoring constituents include the flavoring oils, for example, oils of spearmint, peppermlnt, wintergreen, sassafras, clove, sage, eucalyptus, mar~oram, cinnamon, lemon and orange, as well as methyl~alicylate.
Suitable sweetening agents include lactose, maltose, sorbitol, sodium cyclamate, perillartine, saccharine and ammoniated glycyrrhizin (e.g. its monoammonium salt). Suitably~ flavor and - ~-sweetening agent together comprise from about 0.01 to 5 percent or more of the compositions of the instant inventlon. Preferably the amount of flavoring oil is above 0.3%, e.g. 0.8 to 1.2~.
There may also be included in like amounts, a sweetener of the neohesperidin dihydrochalcone group.
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The dental cream may also contain a fluoride~containing anticaries agent. There are many water-soluble inorganic salts which are suitable sources of fluoride ions. Among these are sodium, potassium, ammonium, manga-nese, and lithium and amine fluorides. The monofluorophosphate salts are also useful and include Na4P309F, K4P309F, ~NH4)P309F, Na3KP309F, (NH4) NaP309F, and Li4P309F. Complex water-soluble fluoride-containing salts such as fluoro-silicate (i.e., Na2SiF6), fluorozirconate (i.e., Na2ZrF6), fluorostannite (i.e., KSnF3), fluoroborate (i.e., NaBF4), fluorotitanate (i.e., NaTiF5), and fluorogermanate ~i.e., K2GeF6) may also be useful. The fluoride ion may also . -be supplied by an organic fluoride which yields fluoride ions in water. Suit-able organic compounds include mono-, di-, and triethanolamine hydrofluoride.
These materials are present in an effective but non-toxic amount, usually within the range to provide about 0.01 to 1 percent by weight of the water-soluble fluorine content thereof to the dentifrice. Sodium fluoride, and sodium monofluorophosphate are the preferred compounds.
Various other materials may be incorporated into the dentifrice pre-parations of this invention. Examples thereof are coloring and whitening agents, preservatives, silicones, chlorophyll compounds, and mixtures thereof, and other constituents. These adjuvants are incorporated in the instant com-20 positions in amounts which do not substantially adversely affect the pro--: .
perties and characteristics desired and are selected and used in proper amount depending upon the particular type of preparation involved. ~ -Particular embodiments of the present invention will now be des-cribed, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a photomicrograph of sodium bicarbonate crystals used in the preparation of the toothpaste of Example 1, Figure 2 is a view of the sodium bicarbonate crystals of Figure 1 in -a scanning electron microscope, and Figure 3 is a photomicrograph of sodium bicarbonate crystals used in the preparation of the toothpaste of Example 2.
Tn this application all proportions are by weight unless otherwise indicated.

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A toothpaste is prepared by forming a gel by mixing a gelling agent, in this case sodium carboxymethyl cellulose ("CMC") with glycerol and water (in the presence of a sweetener, sodium saccharin, a flavor and a preservative, sodium benzoate), then adding to the gel, sodium bicarbonate (baking soda) chalk, and titanium dioxide powder and thereafter degassing the mixture under vacuum. The proportions used are: baking soda, 10%; chalk, 35%; titanium dioxide, 0.4%; deionized water, 16.1%; glycerol, 34.0%; CMC, 1.2%, solution of 35% sodium N-lauroyl sarcosinate in -a mixture of 35% water and 30% glycerol, 2%; sodium lauryl sulfate, 0.98; sodium benzoate, 0.5%; sodium saccharin, 0.2%; flavor, ~:
0.9%. . ~ '.
The baking soda powder in U.S.P grade having the ;
following particle size distribution in which percentages represent the cumulative per cent retained on the named sieve, and sieve sizes are U.S. Standard: #45 sieve, trace; #70 sieve (sieve open-ing 210 microns), 27%, #80 sieve (sieve opening 177 microns) 66.5%; ~
#ioo sieve (sieve opening 149 microns), 92.5%; #170 sieve (sieve ~ ;
opening 88 microns), 99%.
The chalk is U.S.P. precipitated calcium carbonate con-taining at least 98% CaCO3 with no more than 0.2% insoluble in dilute HCl. Its particle size is such that over 99% passes through a U.S. Standard #325 mesh sievej the particles being principally in the 1 to 10 micron size, the average particle size being about 3 microns. A grit free U.S.P. non Fer Al Chalk of similar properties may also be employed with accompanying adjust-ment of gelling agent and viscosity.
The titanium dioxide used is a grit-free anatase powder at least 99O0% of which passes through a #325 U.S. Standard sieve lU4Z8~4 and whose mean particle dlameter (~8 measured on a Kahn sedimen-tation balance) i8 below 1 mlcron, Microscopic measurementR
lndicate lts average particle diameter is 0.3 micron.
The toothpaste has good cleaning power and whiteness and ageæ well in tests at 8F, 40~, 110F, 120F, The toothpa6te has a pleasant smell durlng brushing; whi~e the large particles of bs,klng Roda are moderately palpa~le~they break down to smaller partlcles easily under the pressure o~ the toothbrush and under the actlon Or the sallva.

Example 1 i8 repeated except that the level o~ ch~lk 18 reduced to 25% and the level of sodium blcarbonate lncreased to 20~.

Example 1 i6 repeated except that 5% hydrated alumlna s substituted for 5% o~ the chalk, the proportion of baking soda ema$ns the same, the flavor used i8 a mixture Or essential oil~, argely peppermint.
The hydrated alumina has the ~ollowing particle size i~trlbutlon~ and i6 alpha alumina trihydrate:
28-40% finer than 5 microns ~6-67~ finer than 10 microns ,~5-93~ ~iner than 20 microns 94-99% finer than 30 micron~

Example 3 i6 repeated except that instead of the 5% o~
,ydrated alumina there is employed 5~ zlrconlum sllicate powder the rollowlng particle size di6tribution:
80% finer than 1.25 micronR
~ 90% finer than 1.77 microns 95% finer than 2.15 micron~
99% finer than 2.50 m~rons Ex~mple 3 i8 repeated except that instead of the 5%
of hydrated alumlna there ls used 5~ of micronized silica, and half the baklng soda i~ replaced by a more ~inely divided baking soda havlng the following particle size distribution (in which percen-tages represent the cumulative per cent retained on the named sieve , and sieve slzes are U.S. Standard): #45 sieve (sieve opening 350 microns), trace; #lO0 sieve (sleve opening 149 microns), 0.5%;
#170 sieve (sieve opening 88 microns), 20%; #200 sieve (sleve opening 74 mlcrons), 35~, #325 sleve (sleve opening 44 mlcron~), 70%; ~400 sleve, 80%.
It ls also withln the broader scope of the lnvention to use calcium pyrophosphate (e.g. the B or ~ form of calcium pyrophosphate, or mlxtures of those forms ln various proportions such a~ ln about l:l ratlo, e.g. 53% B, 47% ~), having an average particle s1ze below about 20 microns, e.g. about 1 or 2 to lO
mlcrons, for part of the water-insoluble abrasive in the toothpaste .

Another aspect of this invention r~lates to the de-gassing/toothpastes containing the sodium bi(~arbonate particles.
It i 8 found that when such toothpastes are sub~jected to high vacuum, e.g. above 26 inches of mercury, the paste bubbles and expands but, unlike conventional toothpastes~ it does not con-tract to substantially its original volume on continued vacuum treatment, but instead continues to expand. It has now been found that an excellent deaerated product, having good stability and desirable rheologlcal characteristics can be produced by sub,1ecting the toothpaste containing sodium bicarbonate to a vacuum of at least 26 inches of mercury 80 that it expands to a volume whlch is at least 150~ (e.g. about 200~ of its volume at stmospherlc pressure and then discontinuing the treatment at high vacuum when the expanded mixture begins to contract but while its volume i8 still st least 150% of its volume at atmospheric pressure.
Example 6 This Example illustrates the degassing treatment of this inventlon. 18.3 parts of glycerol; 1.1 ~art of sodium carboxymethyl cellulose; 0.5 part Or sodium benzoate; 0.2 part of sodium saccharln and 15.4 parts of water are mixed at 110-115F.
for 20 minutes and placed in a vertical cylindrical container equipped with a stirrer, specifically a Dopp mixer which has a series of intermeshing counter-rotating radially dispo8ed mixing rods located all along its height. Then 25 parts of calcium carbonate (chalk), 20 parts of sodium bicarbonate, 0.4 part of titanlum dloxide are added and mixed slowly while a vacuum of 27 1/2 inches of mercury is applied; the speéd of mixing i8 then increased; during this vacuum treatment, ~hich la~ts about 5 ~0428Q4 minutes, the batch rises to a volume about 2/3 greater than its volume before vacuum is applied and then decreases somewhat.
The mlxture i~ then vented to the atmosphere and 0.975 parts o~
sodium lauryl sulfate and 2 parts of a solution of 35% sodium lauroyl sarcosinate in a water-glycerol (35~ 30~) mixture are then added, a vacuum 28 2 inches of mercury is applied and the mlxture 18 kept under the vacuum for about 5 minutes while stirring; during ~his time, the volume of the batch increases and decreases somewhat, the volumes being little greater than observed during the preceding vacuum treatment. The mixture is then vent-ed to the atmosphere. 15.1 parts of glycerol are added and the mlxture i8 then stirred under a vacuum o~ 2~ inches o~ mercury ror about 5 minutes during which treatment its volume increa3es by more than 100~ (i.e. to a volume which is more than 200~ of the original volume) and then begins to decrease somewhat. At the conclu~ion o~ this 5 minute period, the ~essel is vented to the atmosphere while the volume of the mixture is still about 75-lOO~ greater than its volume ~ust prior to this vacuum treatment. One part of essential oil flavor is then added, stirring i8 resumed while a vacuum Or 28 l/2 inches is applied;
stirrlng under this uacuum is continued ror about 12 minutes~
arter ~hich the vessel is vented to the atmosphere; durlng thls 12 mlnute period, the expansiQn of the mixture 18 similar to that observed during the immediately preceding vacuum treatment.
Just be~ore the mixture is vented to the atmosphere, the ex-pansion o~ the mixture is still evident.
It is preferable to dlscontinue the vacuum treatment, even though exp~n~ion may continue before the change in pH (i.e. the pH of the vacuum treated mixture minus the -19 - .

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i~ 10428Q4 pH of the mixture without vacuum treatment) reaches one pH unlt and preferably less, e~g. l/2 unit; this avoids decomposltlon o~
sodium bicarbonate and production o~ sodium carbonate during degasslng.
In accordance with a further embodiment Or the invention the toothpaste may be prepared and degassed as ~ollows:
The gel mix is prepared by adding the formula amount o~ glycerine, then adding CMC to vortex of mixing liquid and without heat, mixing ~or 2 minutes, then adding saccharin and sodium benzoate and further mlxing for one mlnute, Thereafter there 1B added the formula amount o~ water, sodium lauryl sulfate and ~lavor. Mlxing i8 then continued for 15 minutes. Mixing i8 continued untll ready to drop the batch. The cover of the Dopp crutcher i5 then closed and there i8 applled 28 inches vacuum and then the vacuum valve i8 closed. Half the gel mix i8 then draw~
in. The mixer i8 then turned of~, the vacuum released and there is added ~ormula amounts of:Titanium dioxide, Sodlum N-lauroyl ~arcosinate, after which there is applied vacuum to 28", while maintaining vacuum until the level o~ the cream drops. The~e is then drawn in the other half o~ gel mix and it i6 dearated ~or 5 minutes at 28 lnches vacuum, Mixer i6 tu~ned O~r, vacuum released and calcium carbonate and sodlum bicarbonate added; apply vacuum wlth mlxing. Continue mixlng for 15 minute~
under full vacuum. With mixer at lower 6p~ed, release vacuum and discharge cream.

~ -~

l 1042804 Thi~ Fxample lllustrQtes the u~e of alphs alumlna .
flakes ln the baking soda toothpaste.
l The toothpaste is made up (usin~, for inRtance, the ¦method o~ Example 1) of 10% of the baking soda powder o~ Example 1, 30% chalk, 5% of ~lpha-alumina flakes, 0.4% titanlum dioxide ¦f Example 1, 33.4% glycerol, 15.4% deionized water, 1,1% CMC
(Hercules 7MF), 2% of a solution o~ 35% sodium N-lauroyl sarcosi-¦nate ln a mixture o~ 35% water and 30% glycerol, 1% sodium lauryl ¦sulfate, 1% flavor (water-lnsoluble essential oil flavoring agent;
le.g., cssentlal oil mlxture rich ln peppermint oll), 0~5% fiodium ¦benzoate and 0.2% sodium saccharln.
The alpha alumina flakes have a mean (by weight) ¦particle diameter of about 4 microns, all the particles thereo~
¦have dlameters less than 10.1 microns, about 85-95% (by weight) ¦have dlameters less than 6.o microns and about 30-35% have partlcle di~meters le~s than 3.5 microns.
The characterlsticæ of the toothpaste Or this Example are ll~e those given in Example 1 above. It has very good re~is-tance to rlavor separatlon.
~XAMPLE 8 .
Example 7 is repeated except that the toothpaste contalns 0.~22% sodium rluoride (the glycerine content being corresponaingly decreased by 0.22%. The toothpaste shows excellent aging characterlstics including very good resistance to ~lavor separation on aging and very good retention -of fluoride content. Like the toothpaste Or Example 8, it hss a high ~olishing effect on enamel; its percent re~olish is 64~.
The ~ercent repolish is determined by a test in which sections of human dental enamel~ upon which have been ground flat areas, are fir~t ~oli.shed, when dulled with chalk, and then brushed with a ~lurry of a dentifrlce for 5000 recipro-cal ~trokes. A " Monsanto Tooth Reflectance Instrument" is em~loyed to measure the s~ecular reflectance of the surface after each step described above. The dulled surface is ad-Justed 80 that it i8 approximately 150 units (Monsanto In-strument) lower than the polished surrace. The polishing ability Or the dentifrlce is expressed by the followlng equation: ( SR -SP
Percent Repolish s 5000 strokes dulled polished - dulled where SR SR and SR
~polished, dulled 5000 strokos are respectively specular reflectance values Or the en~mel surface after the inl-tlal pollshing, after dulllng Nlth chalk, and arter brushlng with a dentlrrlce slurry.

Example 7 18 repeated except that the toothpaste contalns o.76% sodium monorluorophosphate (the glycerine content being correspondlngly decreased by 0.76~).
EXAMPLE lO
Examples 7, ô and 9 are repeated except that the alpha-alumlna flake~ have a mean particle diameter of 5 micron~, sub-stantially all being les~ than about 12 micron~ in dlameter.

' -1()4Z804 This Example illustrates the use of unlined aluminum toothpaste tubes with certain baking soda toothpastes.
~a) A toothpaste is made up (using, for instance, the method of Example 1) of 20% of the baking soda powder (of Example 1) 25% of calcium carbonate, (of Example 1), 0.4%
titanium dioxide of Example 1, 34.02% glycerol, 16.1 deionized water, 1.2%CMC (Hercules* 7MF), 2% of a solution of 35% sodium ~`
N-lauroyl sarcosinate in a mixture of 35% water and 30% glycerol, about 0.9 sodium lauryl sulfate, 0.9 flavor (water-insoluble essential oil flavoring agent; e.g., essential oil mixture rich in peppermint oil), 0.5% sodium benzoate, and 0.2% sodium saccharin.
(b) Example lla is repeated except that 0.5% of fumed silica tCab-0-Sil)* is included, the amount of calcium carbonate is raised to 35%, the amount of baking soda is decreased to 10%.
~c) Example llb is repeated except that the amount of `~
. , .: .
sodium bicarbonate is decreased to 5~ with accompanying changes in other ingredients.
~d) Example 11 is repeated four times, with additional ;
inclusion of various proportions of non-acidic dicalcium phosphate .
dihydrate in the formulation, i.e., in amounts of 0.04%, 0~2%, and 0.8% tbased on the weight of the formulation without said ~;
phosphate); the first case (0.04%) the titanium dioxide is omitted.
The dicalcium phosphate dihydrate is of dentifrice grade and has ;
an average particle diameter of about 4 microns and its pH
(measured in 20% slurry thereof in water is in the range of 9.3 ~ -to 9.9; it yields phosphate ions on contact with water. -~
~e) Example lla is repeated with the additional inclus-ion of insoluble sodium metaphosphate in the formulation in the amount ~ ~
,.......................................................................................... .... .... , ,.,",, *Trade Mark .......................................................................................... .... ... ..

of o.8% (based on the we~ght of the ~ormulation wlthout sald pho~phate). The insoluble sodium metaphosphate is of dentifrice grade having an average particle size of about 5 mlcrons; its pH
(measured in 20% slurry thereof in water) is in the range of 5.3 to 6.3; it yields phosphate ions on contact with water~
(f) Example lla ls repeated except that 5% mlcronized silica 18 substituted for 5% of the calcium carbonate, a different essential oll flavor ls used, the amount of flavor is 0.9% and th~ amount of glycerol is 33.5%.
(g) Example lla i8 repeated except that 3% micronized 8111ca is substituted for 3% Or the calclum carbonate, and the toothpaste contains 0.9% of an essentlal oil ~lavor.
(h) Example lla is repeated except that 5% precipitated sllica 18 ~ubstituted for 5% of the calclum carbonate:
(i) Example lla is repeated except that 5% anhydrous dicalcium phosphate is substituted for 5% of the calcium carbonate;
the toothpaste contains 0.9% of an essential oll flavor. The anhydrous dicalcium phosphate is a fine non-acldlc powder of dentifrlce grade. Its pH (as measured on a 20% slurry thereof water) 18 7.6-7.8; it ylelds phosphate lons, in low concentration, on contact wlth water.
(~) Example lla is repeated except that 5% zirconium sllicate of Example 3 is substituted for 5~ of the calcium carbon-ate (Wlth minor change in proportion and type Or flavor).
(k) Example lla is repeated except that 5% beta phase calcium pyrophosphate i8 8ubstituted for 5% of the calcium carbon- -ate. The calcium pyrophosphate is a fine powder of d~ntifrice grade. It~ pH (as measured on a 20% slurry thereof ln water) i8 5.2-5.3.
Each of the foregoing toothpastes 18 placed ln an 104Z8~4 lndivldual toothpaste tube of unlined aluminum of high purity .
(99.7% Al or purer) and aged. On aging at 120F. the tube fllled wlth the lla toothpaste tends to swell or is found to have a foamy product film in contact wlth the inner aluminum walls of the tube, tubes filled with the llb, c, d, f, g, h, i, 1 and k toothpastes do not show such effects. The 11 preceeding toothpastes show substantially less tendency to react with the walls of the tube than the lla toothpa~te.
The fumed sllica (as in Example llb) is described ln Encyclopedia of Chemical Technology Kirk-Othmor 2nd Edi-tlon, Vol. 18 at pages 62 and 67, for instance. It is with-ln the broader scope of the lnvention to use the fumed sili-ca ln baklng soda toothpaste from which the compatible water-insoluble abrasive (such as calcium carbonate) has been omltted, ln unllned alumlnum tubes. It is also within the broader scope of the invention to employ, ln place of the rumed sillca, very finely dlspersed or dissolved silica ln other rorms such as alkQli metal sllica such as sodium 8ili-cate, e.g. hydrated sodlum slllcate supplled ln flake form con-talnln~ Na20 :S102.H20 in a ratlo of about 1:2-3.2:5, or sodlum slllcate solutions (water glass) such as those ln which the Na20:S102 ratio ls at least about 1:2, or sodium slllcate ~ormed in situ in the dental cream, or colloidal silica or procipitated slllca (see Encyclopedla of Chemlcal Technology Klrk-Othmer, 2nd edltion Vol. 18, pages 63 and 66-67, for ln-stance) or other silicate.
The dicalcium phosph~te dihydrate Or Ex~mple lld is a commerclal stabilized dentifrice grade of this material. A
descrlption of the method of preparation of dlcalcium phos-phate dihydrate and of its stabilization is found in U.S.
patent Or Schlaeger et al 3,169,096 February 9, 1965, who~e di~closure ~ incorporated herein by reference. See also "Cosmetic Sclence" Vol. 1 pub. 1972 (Wlley Interscience) ed-ited by BAlsam and Sagarln pQges 477-479. One typical analy-sis of dicalcium pho~ph~te dihydrate indicates that its content of water-soluble material 18 0.18% (and it~ percent water-solubles expre~sed as P205 is 0.11%). A typical st~bllizeæ

-26_ content i8 a mixture Or about 1-2~ of sodium calcium pyro-phocphate and a smaller amount, e.g. about 0.4~, of pyro-phc~sphoric acid.
The lnsoluble sodium metaphosphate of Ex~mple llc is 5 a commercial dentifrice grade of this material. Its method of preparation and properties are described in the previ-ously cited "Cosmetic Sclence" at pages 480-481 and "Phos-phorus and Its Compounds" by Van Wazer Vol. 2 pub. 1961 (Interscience) page~ 1652-1653.
The anhydrous dicalcium phosphate of Example lli and the calcium pyrophosphate of Example llk are commercial den-tifrice grades of these materials. See the previously cited "Pho~phorus and It~ Compound~" page 1651 and "Cosmetic Sci-ence" pages 479-480.

Example lla is repeated except that the toothpaste contains added anhydrous disodium phosphate (incorporated as a water-soluble powder) in umount of (a) 0.05~ and (b) 0.01%, the amount of water in the toothpaste being ad~usted accord-20 ingly to total 100%. In each case, on aging in unlined aluminumtubes (as in Example 11) the filled tubes do not swell or gas and (after 9 weeks aging at 120F.) the inner walls of the tubes are found to be gold-colored, the wall color in the tube containing the 12b toothpaste being very light. On inspection 25 of the inner walls o~ the unlined aluminum tubes containing the lOd toothpastes (again after 9 weeks at 120 F.) they are ~ound to be dark (when the paste~ contain o.8~ or 0.4,9~ of the dicalcium phosphate dihydrate) or golden (when the tubes con-tain 0.04% and 0.2~ of the dicalcium phosphate dihydrate);

on inspection of the inner walls of the unlined aluminum tubes containing the llk toothpaste they are found to be golden after 3 and 6 weeks aging at 120F. and dark after 9 weeks of such aging. It is believed that the toothpastes containing the dicalcium phosphate dihydrate conta~n (or form, on aging) ~mall amounts of dissolved phosphate ions (e.g. orthophosphate and/or pyrophosphate) which may act on the aluminum wall~, or on the aluminum oxide layer on said walls, to form a protective layer thereon. The amount of dlssolved phosphate ion present in the preferred composition iB sufficient to inhibit the gas-forming reaction between the alkallne toothpaste composition and the aluminum walls of the tube but the amount of the phospahte or acidic ingredient therein is insufficient to cause a gas-forming reaction (e.g.
resulting in swelling or bursting of the tube) between the ingredients of the toothpaste; the tendency for the latter reaction can, of cour e, be tested by placing the composition in a suitably lined aluminum tube (whose walls are thus sub-stantially lnert to the composition) and aging for several weeks (e.g. 9 weeks) at an elevated temperature (e.g. 120F.) Storage of the toothpastes of other types in unlined aluminum tubes i8 discussed in such patents as U.S. 3,662,o66 and 3,678,155 and Austrian 267,070. As is well known to con-sumers of toothpastes, aluminum toothpaste tubes are ~queezed and deformable to express the toothpaste from the nozzle of the tube and the main body of the tube is of relatively thin, ductile, aluminum.

~042804 This Example illustrates the use of olefin ~ulfonate surfactant in a baking soda toothpaste; these olefin sur-factants are found to produce very good foaming during tooth brushing despite the fact that the medium (saliva and baking soda toothpaste) has a relatively high concentration of dis-solved electrolyte.
(a) ~he toothpaste foFmulatlon is the same as that of Example 10 except that in place of the solution of the sarcosinate there is included about Q.7% of a sodium olefin sulfonate detergent and the amount o~ water is increased to about 16.6~.
(b) The toothpaste formulatlon is the same as in Example 10 except that in place of the sodium lauryl sul-fate and the solution of the sarcosinate there is includedabout 1.7% of a sodium olefin sulfonate detergent and the amount of water is increased to about 16.5~.
The olefin sulfonate detergent used in Example 13 is a reaction product of S03 and an olefin mixture (such as may be obtained by cracking paraffin wax) containing approximately equal amounts of 15, 16, 17 and 18 carbon atoms olefins and having an average chain length of about 16 1/2 carbon atoms.
Other olefin sul~onate surfactants may be employed in the baking soda dentifrice. The olefin ~ulfonate surfactants are well known in the detergent art. Generally they contain long chain alkenyl sulfonates or long chain hydroxyalkane sulfonates (with the OH being on a carbon atom which is not directly attached to the carbon atom bearing the -S03-group). More usually, the olefin sulfonate detergent com-prises a mixture of these two types of compounds in varyingamounts, often together with long chain disulfonates or sul-fate-sulfonatss. Such olefin sulfonates are described in many patents, such as U.S. patent noR. 2,061,618; 3,409,637, 1l)4Z804 3~332J880; 3~420~875; 3~428~654; 3~506~580~ and British patent no. 1.139,158, and in the article by Baumann et al in Fette-Sei~en-Anstrichmlttel 72 no. 4 p~ 247-253 (1970)o All the above-mentloned disclosures are incorporated herein by reference. As indicated in these patents and published literature, the olefin sulfonates may be made from straight chain ~ -olefins, internal ole~ins, olefins in which the unsaturation ~n a vinylidene side chain (e.g. dimers of alpha olefins), etc. or, more usually, mixture~ of such compounds, with the c~-ole~in u8uAlly being the maJor constituent. The ~ulfonation i8 usually carried out with sulfur trioxide under low, partial pres6ure, e.g. S03 hi~hly diluted wlth inert gas such as air or nitrogen or S03 under vaCuum.
Thi~ reaction generally yield8 an alkenyl sulPonic acid, often together with a sultone; the resultlng acidic material i8 gen-erally then made alkallne and treated to open the sultone ring to form hydroxyalkane sulfonate and alkenyl sulfonate. The number of carbon atoms ln the olefin i8 usually within the range of 10 to 25, more commonly 12 to 20, e.g. a mixture o~ principally C12, C14 and C16 having an average of about 14 carbon atoms or a mixture of princlpally C14, C16 and C18 having an average o~ about 16 carbon atoms. The preferred olefin sulfonates are sodium salts but it 18 within the broader scope o~ the lnvention to use other water-801uble 8alt8 suCh as ammonium or potas~ium ~alt8.

-3~-- : . 1 - ~

- lO~Z~304 The bakin~ 60da used in the Examples ls a product mnde by precipltAtion from solution (a8 by treatlng a sodlum c~rbonate 801utlon wlth carbon dioxlde to precipitate the bicarbonate) followed by drying, curing with carbon dioxide ga~
and screening to the deslred particle size (generally without substantial crushing or pulverizlng).
These particles are generally monoclinic crystals or tablets or conglomerated thereof (e.g. twinned crystals) some having pro~ecting spike-like portions o~ generally rhombohedral shape wlth many reentraut angles. See Fig. l which is a photo-micrograph of the cry~tals used in Example l and Flg. 2 which i8 A vlew thereof in a scannlng electron mlcroscope. Fig. 3 i8 a photomlcrograph o~ the crystals used in Example 2, The toothpastes of the foregolng Examples are non- :-efrervescent. Thus when diluted with water they do not actively evolve bubbles of carbon dioxide.
The toothpastes of this inventlon have an al~aline pH, generally ln the range of about 8.5 tOl0.0, usually about .3 - 9 9 The dentin abrasion Or the toothpastes may be determined .
by the procedure based on a radioactive technique descrlbed by Grabenstetter et al ln the "Journal of Dental Research", Volume .
37, P. 1060 (1958) as modifled by the descriptlon by Stookey et ~l. ln the "Journal Or Dental Research", Volume 47, page 524 (July-August 1968).

It ls understood that the foregoing detailed des-crlption i~ given merely by way of illustration and that var~ations may be made therein without departing from the spirit of the invention. The "Abstract" given above is merely -~
for the convenience of technical searchers and is not to be given any weight with respect to the scope of the invention.

.

~ .

Claims (34)

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

1. A dental cream containing about 25-60% by weight of an aqueous humectant system and dispersed therein (1) about 1-25% by weight of sodium bicarbonate and (2) about 20-50% by weight of a water-insoluble dental abrasive system compatible with said bicarbonate in the dental cream, said water-insoluble dental abrasive material being selected from the group consisting of silica, alumina, silicates and carbonates non-reactive with the bicarbonate;
the amount of said component (2) being greater than the amount of said com-ponent (1).

2. A dental cream as in claim 1 wherein component (2) is calcium carbonate.

3. A dental cream as in claim 2 wherein component (2) is precipitated calcium carbonate having a density of about 0.7 to 0.9 g/cc, about 99% of which will pass through a 325 mesh sieve.

4. A dental cream as in claim 1 wherein component (2) is flat flakes of alpha-alumina.

5. A dental cream as in claim 1 in a water-glycerol vehicle, the water:
glycerol ratio being in the range of about 0.4:1 to 0.7:1.

6. A dental cream as in claim 1, containing a water-soluble polymeric gelling agent and a water-insoluble essential oil flavoring agent in the range of about 0.5 to 1.5%.

7. A dental cream as in claim 1 containing sodium carboxymethyl-cellulose as gelling agent.

8. A dental cream as in claim 1 containing a compatible surfactant.

9. A dental cream as defined in claim 1 wherein said bicarbonate has a particle size largely principally above about 150 microns but below about 0.4 mm in diameter.

10. A dental cream as defined in claim 1 wherein a major proportion by weight of said bicarbonate has a particle size above about 0.01 mm in diameter.

11. A dental cream as defined in claim 1 additionally containing titanium dioxide included in amounts of about 0.2 to about 6.0 percent by weight of the toothpaste.

12. A dental cream as defined in claim 11 wherein said titanium dioxide is a grit-free anatase powder at least 99.0% of which passes through a No. 325 United States standard sieve.

13. A dental cream as in claim 1 additionally containing sodium fluoride.

14. A dental cream as in claim 1 additionally containing sodium mono-fluorophosphate.

15. A dental cream as in claim 1 additionally containing sodium lauryl sulfate and a higher fatty acid sarcosinate surfactant.

16. A dental cream as in claim 1 additionally containing sodium lauryl sulfate and a higher olefin sulfonate surfactant.

17. A dental cream as in claim 1 additionally containing a higher olefin sulfonate surfactant.

18. A dental cream as defined in claim 1 wherein said dental cream is in an unlined aluminum tube, said dental cream containing an abrasive system in an aqueous vehicle including silica dissolved or dispersed therein.

19. A product as in claim 18, said silica being fumed silica, or sodium silicate.

20. A dental cream as defined in claim 1 wherein said dental cream is in an unlined aluminum tube, said dental cream containing an abrasive system in an aqueous vehicle and additionally containing anhydrous dicalcium phosphate.

21. A dental cream as defined in claim 1 wherein said dental cream is in an unlined aluminum tube, said dental cream containing an abrasive system in an aqueous vehicle and additionally containing calcium pyrophosphate.

22. A dental cream in an unlined aluminum tube, said dental cream con-taining an abrasive system as defined in claim 1 in an aqueous vehicle and additionally containing zirconium silicate.

23. A dental cream as defined in claim 1 wherein said dental cream is in an unlined aluminum tube, said dental cream containing an abrasive system in an aqueous vehicle and containing phosphate ion in amount sufficient to inhibit gas-forming attack on said aluminum tube, said dental cream being stable to gas-formation on storage in inert-walled toothpaste tubes.

24. A dental cream as in claim 23 containing calcium carbonate and dicalcium phosphate dihydrate.

25. A dental cream as in claim 23 containing calcium carbonate and insoluble sodium metaphosphate.

26. A dental cream as in claim 23 containing calcium carbonate and a water-soluble phosphate.

27. A dental cream as in claim 26 in which the amount of said phosphate is such as to cause the inner walls of said unlined aluminum tube to be golden on storage for 9 weeks at 120°F.

28. A dental cream as defined in claim 23, the aluminum walls of said aluminum tube in contact with said toothpaste being covered with a reaction product of phosphate and the aluminum of said walls.

29. A dental cream as in claim 28, said reaction product being gold-colored.

30. A dental cream as defined in claim 1 wherein said sodium bicarbonate has a crystalline structure corresponding to the photomicrograph of Figure 1.

31. A dental cream as defined in claim 1 wherein said sodium bicarbonate has a crystalline structure as shown in the scanning electron photomicrograph of Figure 3.

32. A dental cream as defined in claim 1 wherein sodium bicarbonate is generally monoclinic crystals, some of which have projecting spike-like portions of generally rhombohedral shape with many reentrant angles.

33. A method of making the dental cream as defined in claim 19 compris-ing admixing the glycerine and water of said medium with flavor and said sul-fate and thereafter adding thereto said sarcosinate and components (1) and (2).

34. A packaged dispensable dental product comprising the dental cream as defined in claim 1.