GB2137494A - Sodium bicarbonate-containing tooth powder - Google Patents

Abstract

A tooth powder comprising at least about 50% by weight of sodium bicarbonate particles, wherein said sodium bicarbonate particles have a median particle size of between about 74 and about 210 microns. Flavoring, sweetening, and fluoridating agents may be included in the tooth powder.

Description

SPECIFICATION Sodium bicarbonate-containing tooth powder This invention relates to a sodium bicarbonate-containing tooth powder. More particularly, this invention relates to a sodium bicarbonate-containing tooth powder wherein the sodium bicarbonate particles have a median size within a specific range.

Many different dentifrice compositions are known for cleaning, whitening, and preserving the teeth. Many of these dentifrice compositions include a high content of water-insoluble abrasives, such as dicalcium phosphate, which aid in preventing pellicle and stain build-up on the teeth. In order to preserve the teeth as much as possible, it is widely accepted that the least abrasive material necessary to remove plaque and stain should be used in dentifrice compositions.

Baking soda particles are relatively soft as compared to most conventional abrasive materials used in dentifrice compositions. The American Dentai Association has recommended that "if only a slight degree of abrasion is necessary to keep teeth from staining, baking soda will usually be found satisfactory." Accepted Dentral Therapeutics, pp.340-341 (38th ed., 1979). Toothpaste formulations containing sodium bicarbonate particles as a cleansing agent for teeth have been previously disclosed. See, for example, U.S. 3,943,240 (Delaney et al) and similar patents which disclose a toothpaste composition containing at least about 20%, preferably at least about 30%, sodium bicarbonate particles.The size of the sodium bicarbonate particles in the disclosed toothpaste compositions may vary; but it is preferred that a major portion of the particles be above 0.01 mum and below 0.4mm in diameter. U.S. 2,128,917 (Crocker) also discloses a sodium bicarbonate-containing toothpaste. This patent discloses that the sodium bicarbonate comprises close to 50% by weight of the toothpaste and that the sodium-bicarbonate particles may be sifted through a #200 mesh sieve.

Most dentifrices formulated today are in the form of a paste, gel or powder. Toothpastes and gels generally contain, in addition to the abrasive material, humectants, water, thickeners, surfactants, flavors and sweeteners. Tooth powders generally contain only abrasives, flavor, sweetener and sometimes a surfactant. Both types of products sometimes contain additional ingredients for special functional or aesthetic reasons, for example, fluoridating or coloring agents.

Tooth pastes and gels have gained wider consumer acceptance than powders since they tend to be more convenient to use. However, powder formulations have certain advantages over tooth pastes. For example, humectants, thickeners and water serve no useful purpose in the actual cleaning of teeth but are needed to provide stability to the desired paste or gel form. Powders do not require these ingredients.

One drawback of paste and gels is the cost of the non-cleaning ingredients. Pastes and gels usually contain 20-50% humectant and thickener, representing a disproportionate share (30-50%) of the cost of the finished toothpaste or gel. Tooth powders, which may contain up to 99% useful abrasive materials, eliminate the need for the costly (non-cleaning) humectant and thickener ingredients.

A further drawback of pastes and gels is the difficulty of ensuring that these products have the right consistency, are stable and that the ingredients are compatible. Tooth powders, in contrast, are much easier to formulate.

In the case of pastes or gels containing sodium bicarbonate as the abrasive material, stability of the formulation is a frequent problem. Sodium bicarbonate is unstable in an aqueous solution and reieases carbon dioxide gas. See, e.g., U.S. 3,943,240 at column 1, lines 32-34. Also, sodium bicarbonate is not always compatible with other abrasive materials in pastes and gels. See, e.g., U.S. 3,943,240 at column 2, lines 58-62. In contrast, sodium bicarbonate is stable as a dry powder and is compatible in almost any proportion with most other dry ingredients. Thus, sodium bicarbonate-containing tooth powders have decided advantages over sodium bicarbonate-containing toothpastes or gels.

In addition to the above advantages of a sodium bicarbonate-containing tooth powder, it should be mentioned that it is possible to formulate a tooth powder having a much higher proportion of sodium bicarbonate than is possible in tooth pastes or gels. Sodium bicarbonate. gives a clean, fresh feeling to the mouth. Sodium bicarbonate also helps to deodorize the oral cavity by neutralizing acidic odors. Thus, it is desirable to maximize the sodium bicarbonate content of a dentifrice. However, because of stability problems, it is difficult, if not impossible, to provide more than about 60% sodium bicarbonate in a paste or gel and maintain the product in usable form. A tooth powder, however, may contain higher levels of sodium bicarbonate.

Thus, it is desirable to provide a dentifrice in the form of a tooth powder in which a major proportion of the ingredients comprises sodium bicarbonate particles.

Several tooth powders containing sodium bicarbonate particles have been previously described. U.S.

1,082,681 (Danner), discloses a sodium bicarbonate-containing tooth powder having a fineness of about #30 mesh sieve. U.S. 2,024,146 (Crowther) discloses a tooth powder comprising less than 50% by weight of sodium bicarbonate. The tooth powder passes through a #40 mesh sieve. U.S. 4,276,287 (Cabardo, Jr.) discloses a periodontal powder comprising less than 50% by weight of sodium bicarbonate. The fineness of the sodium bicarbonate particles in this patent is not disclosed. However, none of these patents discloses a sodium bicarbonate-containing tooth powder within the scope of the present invention.In addition, the multipurpose baking soda which is sold to the public, and which often contains a suggestion on the package that it may be used for cleaning the teeth, contains sodium bicarbonate particles having a median particle size in the range of 44-73 microns.

One major problem encountered in formulating a tooth powder having a major proportion by weight of abrasive particles, including sodium bicarbonate particles, is reducing the abrasiveness of the tooth powder to acceptable levels. Excessive abrasiveness can lead to loss of tooth enamel and erosion of exposed dentin.

Abrasiveness is of particular concern in tooth powders since the concentration of abrasives is much higher than in pastes or gels. Also, the ingredients present in the pastes and gels often serve to moderate the abrasivity of the overall formulation.

Another major problem encountered in formulating a tooth powder containing sodium bicarbonate particles is the salty taste of sodium bicarbonate. It has been found that the salty flavor decreases and can be more readily masked if coarser grades of sodium bicarbonate are used in the tooth powder. In order to prepare a sodium bicarbonate-containing dentifrice which is not too salty, the use of large sodium bicarbonate particles is indicated. However, it is known that abrasiveness generally increases with increasing particle size. See, for example, Cosmetics Science and Technology, Vol. 1, pages 427,428 (Wiley-lnterscience, 2d Edition, 1972); Tainter, M.L., and S. Epstein, 30 J.Am. Dent Assoc. pages 1036-1045 (1943).Thus, with the higher levels of sodium bicarbonate present as the principal abrasive in a tooth powder, one would expect that a significant increase in the mean particle size would increase the abrasivity.

It has now been found that, contrary to expectations, a tooth powder containing a major portion by weight of sodium bicarbonate particles can be formulated in which the abrasiveness of the sodium bicarbonate particles decreases with increasing particle size. In accordance with various aspects of the present invention, it is now possible to formulate a sodium bicarbonate-containing tooth powder which is effective in preventing pellicle and stain build-up on the teeth, but is not so abrasive as to deleteriously affect tooth enamel, cementum, or dentin. In addition, the sodium bicarbonate particles are sufficiently coarse so that the tooth powder is not excessively salty but leaves the user with a fresh mouth taste.

In accordance with the present invention, a tooth powder may be prepared comprising at least about 50% by weight of sodium bicarbonate particles, wherein the sodium bicarbonate particles have a median particle size within the range of about 74 to about 210 microns. (As used herein, the term "median" particle size is equivalent to the "mean" particle size.) Preferably, the median size of the sodium bicarbonate particles in the tooth powder is within the range of about 74 to about 149 microns. It has surprisingly been found that such a tooth powder is lower in abrasivity than tooth powders in which the median particle size of sodium bicarbonate is less than 74 microns. In addition, the sodium bicarbonate particles in a tooth powder according to the present invention are sufficiently coarse so that the tooth powder is not unduly salty.

The tooth powder of the present invention comprises at least about 50% by weight of sodium bicarbonate particles within the specified range. Preferably, the tooth powder comprises about 75% to about 98% by weight of sodium bicarbonate. Most preferably, the tooth powder comprises about 90% to about 98% by weight of sodium bicarbonate.

As mentioned previously, tooth powders may contain other ingredients in addition to the sodium bicarbonate. The tooth powder may contain from about 0 to about 50% by weight of additional abrasive materials. Since it is desirable that the tooth powder be low in abrasivity, it is preferred that the additional abrasive materials have RDA's (radioactive dentin abrasion tests) in the range of about 20 to about 100.

Abrasive materials suitable for the present invention are well known in the art and include for example, dicalcium phosphate, chalk, silica, alumina, zirconium silicate, and the like, or mixtures thereof. As also mentioned previously, sodium bicarbonate as a dry ingredient of a tooth powder is compatible with these additional abrasive materials.

The tooth powder of the present invention may also include a suitable flavoring agent. Examples of suitable flavoring agents include the flavoring oils, for example, oils of spearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus, marjoram, cinnamon, lemon, and orange, as well as sodium methylsalicylate. The flavoring agent may be present in the tooth powder in an amount within the range of about 0 to 2% by weight of the tooth powder. A carrier for the flavoring agent may optionally also be present in the tooth powder. Such carriers are well known to those skilled in the art. Suitably, the carrier is present in an amount within the range of about 0 to 5% by weight of the tooth powder.

A sweetening agent may also optionally be included in the tooth powder. Examples of suitable sweetening agents include lactose, maltose, sorbitol, aspartame, and saccharin. The amount of sweetener present in the tooth powder may suitably be within the range of about 0 to 3% by weight. The flavoring and sweetening agents help to mask the salty taste of the sodium bicarbonate.

An anti-caking agent, such as silica or tricalcium phosphate, may be included in the present tooth powder.

Suitably the amount of anti-caking agent is within the range of about 0 to 2% by weight of the tooth powder.

An organic surface active agent may also be incorporated into the tooth powder. The surface active agent aids in cleaning the teeth and also improves the foaming properties of the tooth powders Suitable surface active agents are well-known in the art and include, for example, water-soluble salts of the higher alkyl sulfates, such as sodium lauryl sulfate, water-soluble salts of sulfonated monoglycerides of fatty acids, such as sodium coconut monoglyceride sulfonate, salts of am ides of higher fatty acids with lower aliphatic amino acids, such as sodium lauryl sarcosinate, and the iike. The surface active agent may be present in the tooth powder in amounts ranging from about 0 to about 2% by weight The tooth powder of the present invention may additionally contain a fluoridating agent to aid in preventing dental caries.Many fluoridating agents suitable for use in a dentifrice composition are known.

Among these are sodium, potassium, ammonium, lithium, and amine fluorides, monofluorophosphate salts, such as sodium, potassium, ammonium, and lithium MFP, and other fluoridating agents well known to those skilled in the art. The fluoridating agents are present in an effective but non-toxic amount, such as within the range of about 0 to 2% by weight of the tooth powder. Preferably, the tooth powder of the present invention will contain about 0 to 0.5% by weight of sodium fluoride or O to 1% by weight of sodium MFP as the preferred fluoridating agent.

In a preferred form, the tooth powder of the present invention contains between about 75 and about 98%, most preferably between about 90 and about 98%, by weight of sodium bicarbonate particles having a median particle size within the range of about 74 to about 149 microns, and about 0.22% by weight of sodium fluoride.

The following examples will serve to illustrate the practices of the present invention.

Example 1 Tests were run to show the effect of the concentration of sodium bicarbonate particles on the abrasiveness of dentifrice compositions. In runs 1,2 and 3 shown below, different amounts of multipurpose baking soda having a median particle size within the range of 44-73 microns were mixed with 50 ml of water containing 0.5% of carboxymethyl cellulose (CMC) as a thickener. The mixtures were subjected to the well-known radioactive dentin abrasion (RDA) and the radioactive enamel abrasion (REA) tests. The results are shown in Table I. Table I also shows the results when comparable RDA and REAtests were performed on two commercial toothpastes which do not contain sodium bicarbonate. Paste A (Crest with-fluoristat) contains hydrated silica as the dental abrasive.Paste B (Colgate dental cream) contains dicalcium phosphate as the dental abrasive.

TABLE I Concentration RDA REA Baking Soda 10g NaHCO3/50ml H20 25 16 Baking Soda 25g NaHCO3/50ml H20 62 16 Baking Soda 50g NaHCO3/50ml H20 68 20 Paste A 25gi50ml H20 67 50 Paste B 25g/50ml H20 46 14 As expected, the results in Table I show an increase in abrasivity with increasing concentration of sodium bicarbonate particles.

Example 2 A preferred tooth powder was formulated comprising 97.32% of sodium bicarbonate particles, wherein the median size of the sodium bicarbonate particles was in the range of 74-149 microns, 2% flavoring and saccharin, 0.22% sodium fluoride, and traces of other ingredients. The tooth powder was mixed with 50 ml of water containing 0.5% CMC and was tested as in Example 1 for abrasivity by the RDA and REA tests at different concentrations. The results are shown in Table II.

TABLE II Concentration RDA REA Baking Soda 10g NaHCO3/50ml HzO 21 16 Baking Soda 259 NaHCO3/50ml H20 52 16 Baking Soda 509 NaHCO3/50ml H20 54 13 These results, when compared to the results of Table I, demonstrate that sodium bicarbonate particles having a median particle size within the range of 74-149 microns are less abrasive than sodium bicarbonate particles having a median particle size within the range of 44-74 microns.

Example 3 The abrasivity of sodium bicarbonate particles of different sizes as compared to calcium pyrophosphate was tested by the RDA test. The results are shown in Table III.

TABLE III Median Particle Size Average RDA Calcium pyrophosphate 100 Baking Soda < 44 > 39 Baking Soda 44-73 28 Baking Soda ~ 74 > 25 Baking Soda > 149 > 22 The results show that sodium bicarbonate is much lower in abrasivity than calcium pyrophosphate. The results also show that the abrasivity of sodium bicarbonate particles decreases as the median particle size increases. Thus, a tooth powder low in abrasivity and low in salty flavor can be formulated which is comprised of a major proportion by weight of sodium bicarbonate particles having a median size within the specified range.

While the invention has been described by reference to specific embodiments, this was for purposes of illustration only and should not be construed to limit the spirit or scope of the invention.

Claims (21)

1. A dentifrice composition comprising at least about 50% by weight of sodium bicarbonate particles as a dental abrasive material, wherein the sodium bicarbonate particles have a median particle size within the range of 74 to 210 microns, said dentifrice composition being in the form of a tooth powder.

2. The dentifrice composition of claim 1 wherein the median particle size of said sodium bicarbonate particles is within the range of 74 microns to 149 microns.

3. The dentifrice composition of claim 2 further comprising an additional ingredient selected from the group consisting of a second dental abrasive material, a fluoridating agent, a flavoring agent, a carrier, a sweetening agent, a surface active agent, an anti-caking agent, and mixtures thereof.

4. The dentifrice composition of claim 3 wherein said second dental abrasive material has a RDA in the range of 20 to 100.

5. The dentifrice composition of claim 3 wherein said fluoridating agent is sodium fluoride or sodium MFP.

6. The dentifrice composition of claim 3 wherein the sweetening agent is aspartame or saccharin.

7. A dentifrice composition comprising between 75% and 98% by weight of sodium bicarbonate particles as a dental abrasive material, wherein the sodium bicarbonate particles have a median particle size within the range of 74 to 149 microns, and 0% to 2% by weight of a fluoridating agent, said dentifrice composition being in the form of a tooth powder.

8. The dentifrice composition of claim 7 wherein said sodium bicarbonate comprises 90% to 98% by weight of said tooth powder.

9. The dentifrice composition of claim 8 wherein said fluoridating agent comprises about 0.22% by weight of sodium fluoride.

10. The dentifrice composition of claim 9 further comprising about 2% by weight of a flavoring agent, sweetening agent, or mixtures thereof.

11. A method for cleaning the teeth and gums comprising applying a tooth powder to said teeth and gums, said tooth powder comprising at least about 50% by weight of sodium bicarbonate particles as a dental abrasive material, wherein the sodium bicarbonate particles have a median particle size within the range of 74 to 210 microns.

12. The method of claim 11 wherein the median particle size of said sodium bicarbonate particles is within the range of 74 to 149 microns.

13. The method of claim 12 further comprising an additional ingredient selected from the group consisting of a second dental abrasive material, a fluoridating agent, a surface active agent, a sweetening agent, a flavoring agent, a carrier, an anti-caking agent, and mixtures thereof.

14. The method of claim 13 wherein said second dental abrasive material has a RDA in the range of 20 to 100.

15. The method of claim 13 wherein said fluoridating agent is sodium fluoride or sodium MFP.

16. The method of claim 13 wherein said sweetening agent is saccharin or aspartame.

17. A method for cleaning the teeth and gums comprising applying a tooth powder to said teeth and gums, said tooth powder comprising between 75% and 98% by weight of sodium bicarbonate particles as a dental abrasive material, wherein the sodium bicarbonate particles have a median particle size within the range of 74 to 149 microns, and 0% to 2% by weight of a fluoridating agent.

18. The method of claim 17, wherein said sodium bicarbonate comprises 90% to 98% by weight of said tooth powder.

19. The method of claim 18 wherein said fluoridating agent comprises about 0.22% by weight of sodium fluoride.

20. The method of claim 19 further comprising about 2% by weight of a flavoring agent, a sweetening agent, or mixtures thereof.

21. A dentifrice composition substantially as described in the examples herein.