US2216821A - Dentifrice - Google Patents

Description

Patented Oct. 8, 1940 PATENT OFFICE DENTIFRICE Homer 0. Long, Golf, 111., assignor to The, Pepsodent 00., Chicago, 111., a corporation of Illinois No Drawing.

.4 Claims.

The present invention relates to dentifrlces and the like, and comprehends among its objects to provide a novel dentifrice which contains a novel combination or composition of substances whereby the dentifrice 'has a high degree of polishing and cleansing action with no deleterious effect on the enamel of the teeth; also has the property of readily slipping over the surface of the teeth when applying the dentifrice thereto than here--' tofore; has, furthermore, the property of preventing syneresis (bleeding) in the case when the dentifrice is in the form of a paste; has the characteristic of eliminating the tendency of packing when the dentifrice is in the form of a powder;

and also prevents decalcification of the tooth enamel by inhibiting the solvent action of any of the ingredients on the enamel of the teeth.

Other objects, advantages and capabilites are comprehended by the invention as will later appear and are inherently possessed thereby.

More specifically, my novel dentifrice comprises a combination or composition of insoluble sodium metaphosphate and a magnesium compound. Many, but not all, of the available magnesium compounds will perform one or all of the functions herein disclosed. As examples of magnesiumcompounds which will fail to perform at least one of the-functions disclosed, magnesium glycerophosphate, magnesium citrate, magnesium tartrate, magnesium lactate, magnesium pyrophosphate, magnesium chloride and magnesium sulphate may be cited as magnesium compounds which in reasonable proportion fail to abolish the enamel decalcifying tendencies of .the metaphos- 5 phate. 4

' The following specific magnesium compounds are illustrative of some of those which will sue-- cessfully fulfill the important functions outlined, and especially the prevention of decalcification of 40 tooth enamel: tri-magnesium phosphate, magnesium oxide, magnesium hydroxide, magnesium carbonate, alkaline magnesium silicate. It is of interest that monmmagnesium phosphate oifers some advantages in the prevention of decalcifica- 5 tion, and'that by the joint use of mono-magnesium phosphate and an alkaline magnesium compound, the requisite total amount of magnesium compound may be added and the pH of the finished dentifrice controlled. 50 The selection of a specific magnesium .compound or of a mixture of specific magnesium compounds to fulfill the function's setforth will rely more upon the inherent normal properties of these products than upon the specific functions described herein, since with such a-wide. variety Application November 4, 1938, Serial No. 238,844

of compounds, each of which can fulfill novel functions, the secondary characteristics will offer a basis of preference depending upon the exact type of product which is desired. I prefer to consider trl-magnesium phosphate as an example of one of the most practicable magnesium salts.

When making a paste of insoluble sodium metaphosphate as a polishing agent alone a cream is produced which is translucent. Consumer preference, however, has established that the paste should be opaquely white. By my invention I produce a dental cream in which I use, as a polishing agent, a combination or composition of insoluble sodium metaphosphate and a magnesium salt, such cream having the desired opacity and color.

Ground insolublesodium metaphosphate because of the shape and size of its particles, binds and is difficult to'move, as through the ducts of the manufacturing devices and also as through the outlet of the tooth paste tubewhen the paste is subjected to pressure. In other words, the re-' sistance to strain is very high. To make the dentifrice in the most sanitary way it is necessary it benot touched by norhandled with the hands of the workers. It should be mixed and manipulated by modern'machinery and pumps and fed through pipes or ducts to the filling machines Where, under sanitary conditions, the dentifrice is fed into collapsible tubes. I

Ihave discovered that when a magnesium salt is incorporated with the insoluble sodium metaphosphate, a' desirable slip is obtained, that is, the resistance to strain or fluidal flow is greatly reduced. This is very valuable in the manufacturing process and also when exuding the paste from the tube.

Also, when a toothpaste is made with only insoluble sodium metaphosphate as a polishing agen the interparticle spaces are such as to release the fluid phase and the paste undergoes, with pressure on it, syneresis or bleeding as it is more commonly termed. I have discovered that the incorporating of a magnesium salt will lessen this condition. Magnesium. salts are capable of being extremely finely powdered even to the particle size of a micron. So far as I can ascertain, this fine powder apparently fills the interstitial spaces of the insoluble sodium metaphosphate component with the massing agent and prevents the tooth paste tube, b1eeding-being prevented at all such points. Accordingly, the including of the magnesium salt as a component prevents syneresis or bleeding by (a) filling the interparticle spaces of the insoluble sodium metaphosphate, and (b) increasing the slip of the finished paste.

In the case of a tooth powder, if the insoluble sodium metaphosphate is used alone it has a tendency to pack and not to 'sift or flow freely from the container. By incorporating a magnesium salt these disadvantages or tendencies are materially overcome.

It is economically commercially extremely difficult, if not impossible, to manufacture 100% pure insoluble sodium metaphosphate. As I use it there is a maximum of 3% of soluble material formed in the insoluble sodium metaphosphate from mono-ortho-sodium phosphate. This soluble material is acidic in reaction and shows a tendency to decalcify human tooth enamel which may or may not be related to the acidity. The addition of a suitable magnesium salt, for example, the addition of tri-magnesium phosphate, has the property of bufi'ering this acidic reaction. However, the fulfillment of the functions set forth does not appear to be directly or essentially dependent upon such buffering action insofar as the word buffering" is used to imply a control of acidity. While it is true that the addition of a magnesium compound in sufilcient quantity to accomplish such buffering of acidity will inherently fulfill the other functions described, it is pointed out that the addition of a magnesium compound which is in itself acidic may also fulfill such functions at least to a significant degree.

The tendency of insoluble sodium metaphosphate to attack tooth enamel has only been and probably can only be demonstrated by more or less artificial experiments. It is entirely possible that such tendencies demonstrated in such ways are due not to the chemical compound insoluble sodium. metaphosphate but rather to the soluble impurities which by their very solubility must obviously be classed as contaminants. Since-it appears impracticable if not impossible to prepare insoluble sodium metaphosphate in commercial quantities in a condition which is and remains free of such soluble impurities, the calcium dissolving tendencies of such commercial mixtures has been discussed as a property of the insoluble sodium metaphosphate without proper realization and clarification of the true causes underlying such action.

The addition of a magnesium compound may therefore be regarded primarily as the addition of a substance to modify the action not of insoluble sodium metaphosphate itself but of the impurities which accompany it to greater or lesser degree. The quantity of such magnesium compound which is necessary therefore will be determined not only by the nature of the magnesium compound chosen but also by the purity of the commercial insoluble sodium metaphosphate with which tests are conducted. It has been specifically proven that five-tenths of one' per cent of magnesium oxide when mixed with a commercial but-relatively pure grade of insoluble sodium metaphosphate will yield a composition which will have no decalcifying effect upon human tooth enamel. I

The tests used to detect such decalcifying action and subsequently to prove the absence of such decalcifying action are as follows:

Tests have been conducted on pulverized human tooth enamel with a subsequent determination of the amount of calcium converted to a soluble form. This method of determination is subject to severe criticism in that any suspended calcium compound is likely to be determined as a solubilized calcium. A more satisfactory test is achieved when an extracted human tooth is covered with a protective coating of wax or other suitable substance, leaving a small window of enamel surface exposed, and when such partially coated tooth is submersed in a suspension of the dentifrice composition to be tested in water, if there is an active decalcifying tendency the exposed enamel under the window in the wax coating will become etched. If no such etching is determined even by microscopic examination after a continuous exposure of as long as three to thirty days, the mixture so tested is deemed to be free of decalcifying tendencies.

In adding a magnesium compound to overcome such decalcifying tendencies as commercial insoluble sodium metaphosphate may exhibit, it is deemed advisable to add an excess over the minimum quantity necessary to prevent the decalcification of tooth enamel by the test last referred to above. All of the effective magnesium compounds previously listed have been so tested and found to protect.

The proportions of the ingredients may vary between wide limits without departing from successful results or the spirit of my invention. For illustration, I can use less than one per cent of magnesium compound (such as magnesium oxide or tri-magnesium phosphate) to more than ninety-nine per cent by weight of insoluble sodium metaphosphate. I can also use more than fifty per cent by weight of magnesium compound but prefer to use less than fifty per cent. The reason for preferring to use less than fifty per cent by weight of magnesium compound is simply that the unusual and desirable cleansing and polishing actions of insoluble sodium metaphosphate become less pronounced when the proportion of this desirable substance is unduly reduced in favor of unnecessary quantities of magnesium compound. However, for producing generally optimum results for the various purposes of my invention, satisfactory results are obtained by the following proportions:

' Per cent Insoluble sodium metaphosphate 93 Magnesium compound (from list given earlier herein) '7 In the formula given above it is understood that any of the magnesium compounds set forth in this application when used in the proportion indicated with a reasonably pure grade of insoluble sodium metaphosphate will completely overcome any decalcifying tendencies of the insoluble sodium metaphosphate and will also serve to fulfill one or more of the other functions outlined. It is understood that this general formula may be modified by the addition of flavoring agents, detergents, coloring material and such other of the customary dentifrice ingredients as may be desired and as may be compatible with this basic formula. It is also understood that the magnesium compound chosen will to some extent influence the taste, feel and other properties of the dentifrice.

More specific formulas which have been found Tooth powder Per cent Insoluble sodium metaphosphate 84.00 Tri-magnesium phosphate 9.85 Gum 3.00 Alkyl sulphate 1.00 Flavors 2.15

Insoluble sodium metaphosphate 86.85 Tri-magnesium phosphate 10.00 Alkyl sulp 1.00 Flavor 2.15

Insoluble sodium metaphosphate 95.60 Magne ium mild. 1.00 Alkyl sulpha 1.25 Flavor 2.15

Insoluble sodium metaphosphate 89.60 Magnesium carbonate 7.00 Alkyl sulph 1.25 Flavor 2.15

Toothpaste v Pounds Insoluble sodium metaphosphate 75.00 Magnesium hydroxide .75 Glycerol 32.00 Water 19.58 Alkyl sulphate .42 Flavor g .698

Insoluble sodium metaphosphate 75.00 Magnesium carbonate .75 Gum 2.50 Glycerine 32.00 Water 19.58 Alkyl sulphate .42 Flavor l .70

Insoluble sodium metaphosphate 52.48 Tri-magnesium phosphate 4.20 Gum 1.75 Glyeerlne I 35.82 Water 15.81 Alkyl sulphate .29 Flavor .65

other functions herein set forth have, also been fulfilled, but which also have been found to'represent satisfactory practical formulas, are as follows:

Insoluble sodium metaphosphate 148.50

Pounds Magnesium oxide 1.50 Gum 5.00 Glycerine 66.80 Water 44.00 Alkyl sulphate 1.00 Flavor 1.30

The specific formulas Just given have all been found practical, workable formulas to achieve the ends set forth. It is to be understood, however, that the specific formulas given should not be construed to set any limitations upon the scope of the invention, as different magnesium compounds or difierent percentages thereof or the inclusion of other desirable ingredients or the exclusion of any of the additional ingredients specified in these formulas may be availed of without departing from the scope of the invention as set forth. I

In the disclosure as made nd in the examples as given, the amount of magnesium compound is n all cases deemed to be in excess. of the minimum amount to accomplish the functions set forth and in excess specifically of the minimum quantities necessary to completely pre- 1 vent any decalcifying action upon tooth enamel.

The scope of this application should, therefore, cover the use of a magnesium compound in quantities substantiall .less than those set forth as most desirable.

Having now described my invention, I claim:

1. A dentifrice composition consisting predominantly of insoluble sodium metaphosphate and including a suitable percentage as from 1% to 7% of magnesium compound chosen from the group consisting of magnesium oxide, magnesium hydroxide, magnesium carbonate, alkaline magnesium silicate, trimagnesium phosphate, and mono-magnesium phosphate.

2. A dentifrice composition consisting predominantly of insoluble-sodium metaphosphate and including from 1% to 7% of magnesium hydroxide.

3. A dentifrice composition consisting predominantly of insoluble sodium metaphosphate and including from 1% to 7% of magnesium carbonate.

4. A. dentifrice containing, as its essential Hem D. LONG.