WO2002002060A2

WO2002002060A2 - Oral compositions

Info

Publication number: WO2002002060A2
Application number: PCT/US2001/020611
Authority: WO
Inventors: Vincent Bercovici; Robert Francis Date; Kieran John Michael Madigan; Christopher David White
Original assignee: The Procter & Gamble Company
Priority date: 2000-06-30
Filing date: 2001-06-28
Publication date: 2002-01-10
Also published as: GB0016067D0; WO2002002060A3; PE20020139A1; AU2001270235A1

Abstract

The invention relates to oral compositions providing improved cleaning of teeth. The compositions comprise a cleaning silica, having a particle size ranging from 8 to 14 ν, an oil absorption ranging from 60 to 120 cm3/100 g, and a mercury intrusion (HGI) void volume of 1.0 to 4.0 cm3/g; the silica, when formulated into a dentifrice, having a Pellicle Cleaning Ratio (PCR) of from 70 140 and a Radioactive Dentin Abrasion (RDA) value of from 60 to 130, wherein the ratio of the PCR to the RDA is at least 1.1. The compositions further comprise a phosphate ester of myo-inositol, such as phytic acid, or a salt thereof.

Description

ORAL COMPOSITIONS

Field of the Invention

The present invention relates to dentifrice compositions such as toothpastes, which provide improved oral cleaning. More particularly the invention relates to oral compositions comprising a cleaning silica and a phytic acid compound.

Background Of The Invention

A satisfactory dentifrice composition should have a cosmetic effect upon the teeth, namely, keeping them light coloured. It should also clean and remove debris as well, thereby aiding the prevention of tooth decay and promoting gingival health. Abrasives aid in the removal of the tightly adherent pellicle film. This film usually comprises a thin acellular, glycoprotein-mucoprotein coating which adheres to the enamel within minutes after teeth are cleaned. The presence of various food pigments lodged within the film accounts for most instances of teeth discoloration. Ideally, an abrasive should provide satisfactory removal (cleaning) of the pellicle film with minimal damage (abrasion) to oral tissue, i.e. the dentine and enamel.

The use of a variety of agents to clean the oral cavity and reduce plaque and mouth malodour has been recognised for some time. Examples include the disclosures of U.S. patents 4,138,476; 4,140,758; 4,154,815; 4,737,359; 4,986,981; 4,992,420; 5,000,939; 4,652,444; 4,725,428; and 4,355,022. Other patent publications in the same field include WO 86/02831, JP 02/105,898; JP 03/128,313 and JP 03/223,209. Abrasives are described in US-A-4,340,583, US-A-3,574,823, EP-A-535,943 and WO 92/02454.

Oral compositions comprising phytic acid compounds are known. US-A-4,259,316 and US-A-4,335,102 describe oral compositions for caries prophylaxis. US-A-3,934,002 relates to oral compositions, such as toothpastes, which contain an anti-calculus agent which inhibits the tendency of a bis-biguanide compound to produce a stain on oral surfaces. US-A-4,263,276 and US-A-4,305,928 disclose the use of phytic acid, in dentifrices containing a siliceous polishing agent and a dye, to prevent or reduce colour fading. WO 93/07850 describes stannous compositions for reducing plaque and gingivitis which can comprise phytic acid and silicas. WO 93/11740 teaches phytate compositions comprising cationic anti-microbial compounds. EP-A-329,069 describes phytate oral compositions which inhibit hydroxyapatite formation.

In spite of the many disclosures relating to compositions for cleaning and stain removal, the need for improved products still exists. The present inventors have developed oral compositions oral compositions incorporating a particular silica abrasive and a phytic acid compound which providing improved pellicle cleaning and stain removal and prevention.

It is therefore an object of the present invention to provide an oral care product and methods of using the same directed at pellicle cleaning and in particular for preventing or reducing stain on teeth. It is a further object of the present invention to provide compositions and methods which are effective in arresting the accumulation of plaque and preventing gum disease. A still further object of the present invention is to provide compositions that will also abate subsequent calculus formation and stain build up.

These objectives and additional objectives will become readily apparent from the detailed description which follows.

Summary Of The Invention

The present invention relates to dentifrice compositions comprising: a) from 1% to 95% of a low structure precipitated silica having a mean value (MV) particle size ranging from 8 to 14 μm, an oil absorption ranging from 60 to 120 cm^/lOO g, and a mercury intrusion (HGI) void volume of 1.0 to 4.0 cm-Vg; the silica, when formulated into a dentifrice, having a Pellicle Cleaning Ratio (PCR) of from 70 to 140 and a Radioactive Dentin Abrasion (RDA) value of from 60 to 130, wherein the ratio of the PCR to the RDA is at least 1.1; b) from 0.1 % to 20% of a phytic acid compound; and c) from about 0.1 % to about 99% of an orally-acceptable carrier.

The present invention further relates to a method for preventing or reducing stain on teeth comprising the application of the compositions to the teeth. All percentages and ratios herein are by weight unless otherwise specified. Percentages are by weight of the total composition unless otherwise specified and, in relation to ingredient levels refer to the amount on a 100% active basis, unless otherwise specified. PCR and RDA are unitless. Additionally, all measurements are made at 25°C. unless otherwise specified.

Detailed Description Of The Invention

A "safe and effective amount," as used herein, means a sufficient amount to reduce stain and/or plaque/gingivitis without harming the tissues and structures of the oral cavity.

The term "orally-acceptable carrier," as used herein, means a suitable vehicle which can be used to apply the present compositions to the oral cavity in a safe and effective manner.

The pH of the present compositions generally range from about 3 to about 9, preferably from about 6 to about 8.

The essential as well as optional components of the compositions of the present invention are described in the following paragraphs.

Silicas

The precipitated silicas of the present invention provide unique Radioactive Dentin Abrasion (RDA) values in the dentifrice compositions of the present invention and are characterised by having a mean value particle size (MV) as measured on a Microtrac Particle Analyzer, in the range of about 8 to about 14 μm and more preferably from 8 to 10 μm. These silicas also have good fluoride compatibility. The silicas and their manufacture are described in more detail in WO 96/09809, incorporated herein by reference.

Preferred precipitated silica materials include those available from the J.M. Huber Corporation under the tradename Zeodent®, particularly the silica carrying the designation Zeodent® 118.

Certain of the precipitated silicas of the present invention can also be characterised as agglomerated or cohered silicas wherein subparticles are cohesively bound together during the process of acidulation and/or curing to form the agglomerated precipitated silicas having the mean particle size of 8 to 14 μm. Preferably greater than about 2%, more preferably greater than about 5%, even more preferably greater than about 10% and most preferably greater than about 15% by weight of the precipitated silica particles of the present invention are made up of these agglomerates. Agglomeration is not a result of the addition of a binding agent to the process, but rather is a natural agglomeration caused by physical binding characteristics of the subparticles. It is theorised that during digestion and subsequent curing, the particles of silica become more unifonn in size by a process of cohesion of smaller particles and breaking apart of large agglomerates.

It is therefore theorised that when used in dentifrice formulations, the agglomerated particles break down during the brushing process when in contact with dentine or enamel so that the precipitated silica particles appear to be softer particles when used in the dentifrice formulations. This property, when considered with the fact that the precipitated silicas already possess lower RDA values than alternate silicas, provides dentifrice compositions with increased cleaning but lower abrasiveness. Therefore, a feature of the precipitated silicas of the invention is that they are agglomerated precipitated amorphous silicas of substantially uniform particle size and having mean particles sizes of 8 to 14 μm, and more preferably from 8 to 10 μm, and which have reduced RDA values as compared to the prior art.

A feature of these precipitated silicas is the relationship of the mean particle size and exhibited RDA. The preferred precipitated silicas of the invention have a mean particle size of 8 to 14 μm and also unexpectedly have a relatively lower abrasivity or hardness than other silicas of the same particle size. This relatively lower abrasivity for a low structure silica is unique to the precipitated silicas of the invention.

The precipitated silicas of the invention are Low Structure silicas in accordance with the definitions set forth in the J. Soc. Cosmet. Chem. 29., 497-521 (August, 1978), and Pigment Handbook: Volume 1, Properties and Economics, Second Edition, Edited by Peter A. Lewis, John Wiley & Sons, Inc., 1988, p. 139-159. Further, the precipitated silicas may be characterised as having an oil absorption ranging from 60 to 120 cm^/lOO g and preferably 80 to 100 cm^/lOO g, more preferably about 90 cm^/lOO g. The silicas may also be characterized as having a BET surface area in the range of 50 to 250 m^ /g.

A further feature of the precipitated amorphous silicas of the invention is the porosity as determined by mercury intrusion (HGI) void volume measurements. The silicas of this invention have mercury intrusion values in the range of 1.0 to 4.0 cmVg and preferably 1.5 to 2.5 cm^/g. A further feature of the precipitated silicas of the invention resides in the pH which ranges from 4.0 to 8.5 and preferably from 6.5 to 8.5, as measured in a 5% aqueous slurry.

The Pellicle Cleaning Ratio (PCR) of the inventive silica, which is a measurement of the cleaning characteristics of a dentifrice, ranges from 70 to 140 and preferably from 100 to 130 for the precipitated silica of the invention. The Radioactive Dentin Abrasion (RDA) of the inventive silicas, which is a measurement of the abrasiveness of the precipitated silicas of the invention when incorporated into a dentifrice, ranges from 60 to 130, preferably from 60 to 100, and more preferably from 80 to 90.

The silicas of the invention may also be characterised as having a pour density ranging from 0.19 - 0.26 g/cm^, a pack density ranging from 0.4 to 0.5 g/cm^ and median average particle size ranging from 7 to 11 μm.

These silicas, when incorporated into a dentifrice composition provide an improved PCR/RDA ratio. The PCR/RDA ratio is used to determine the relative ratio of cleaning and abrasion characteristics of a dentifrice formulation. Commercially available dentifrice formulations generally have a PCR/RDA ratio in the range of 0.5 to below 1.0. The precipitated silicas used in the compositions of the present invention provide PCR to RDA ratios to dentifrice formulations of greater than 1, usually in the range of 1.1 to 1.9, but more preferably in the range 1.2 to 1.9.

The precipitated silicas of the invention are preferably characterised as synthetic hydrated amorphous silicas, also known as silicon dioxides or Siθ2- This definition is intended to include gels and hybrids of silicas such as Geltates.

The RDA (Radioactive Dentine Abrasion) values are determined according to the method set forth by Hefferren, Journal of Dental Research, July- August 1976, pp. 563- 573, and described in the Wason US patents US-A-4,340,583, US-A-4,420,312 and US- A-4,421,527, which publication and patents are incorporated herein by reference.

The PCR (Pellicle Cleaning Ratio) cleaning values are determined by a slightly modified version of the PCR test described in "In Vitro Removal of Stain With Dentifrice", G. K. Stookey, T. A. Burkhard and B. R. Schemerhorn, J. Dental Research, 61, 1236-9, 1982. Cleaning is assessed in vitro by use of the modified pellicle cleaning ratio test.

This test is identical to that described by Stookey et al. with the following modifications: (1) a clear artificial pellicle film is applied to bovine chips prior to application of the stained film, (2) solution heating is used rather than radiative heating during film application, (3) the number of brush strokes is reduced to 200 strokes and (4) the slurry concentration is 1 part dentifrice to 3 parts water.

In the present specification, oil absorption is measured using the ASTM rubout method D281. Surface area is determined by the BET nitrogen adsoφtion method of Brunaur et al, J. Am. Chem. Soc, 60, 309 (1938). To measure brightness, fine powder materials that are pressed into a smooth surfaced pellet are evaluated using a Technidyne Brightimeter S-5/BC. This instrument has a dual beam optical system where the sample is illuminated at a angle of 45°, and the reflected light viewed at 0°. It conforms to TAPPI test methods T452 and T646, and ASTM Standard D985. A series of filters direct to reflected light of desired wavelengths to a photocell where it is converted to an output voltage. This signal is amplified and then processed by an internal microcomputer for display and printout.

The average particle size (mean value and median or 50%) is measured using a Microtrac II apparatus, Leeds and Northnap. Specifically, a laser beam is projected through a transparent cell which contains a stream of moving particles suspended in a liquid. Lights rays which strike the particles are scattered through angles which are inversely proportional to their sizes. The photodetector array measures the quantity of light at several predetermined angles. Electrical signals proportional to the measured light flux values are then processed by a microcomputer system to form a multi-channel histogram of the particle size distribution.

The pore volumes (mercury pore volume) are determined using an Autopore II 9220 Porosimeter (Micromeritics Corporation). This instrument measures the void volume and pore size distribution of various materials. Mercury is forced into the voids as a function of pressure and the volume of mercury intruded per gram of sample is calculated at each pressure setting. Total pore volume expressed herein represents the cumulative volume of mercury intruded at pressures from vacuum to 416MPa (60,000 psi). Increments in volume (cm-Vg) at each pressure setting are plotted against the pore radius corresponding to the pressure setting increments. The peak in the intruded volume versus pore radius curve corresponds to the mode in the pore size distribution. It identifies the most common pore size in the sample.

The silicas can be further characterised using a Einlehner At- 1000 Abrader to measure the softness of the silicas in the following manner: A Fourdrinier wire screen is weighed and exposed to the action of a 10% aqueous silica suspension for a certain length of time. The amount of abrasion is then determined as milligrams weight lost of the Fourdrinier wire screen per 100,000 revolutions. Brass Einlehner (BE) results are expressed in milligrams. The silicas preferably possess a BE of less than about 7 and preferably between 2 and 5.

The silica in the compositions described herein is generally present at a level of from about 1% to about 50%, preferably from about 5% to about 35% when the dentifrice is a toothpaste. Higher levels, as high as 95%, may be used if the composition is a toothpowder.

Phytic acid compound

The compositions of the invention comprise from 0.1% to 20%, preferably from 0.5% to 10%, more preferably from 1% to 6% of a phytic acid compound. The hexakis phosphate ester of myo-inositol is known as phytic acid. As used herein "phytic acid compound" means the hexakis phosphate ester of myo-inositol and the lesser substituted trikis, tetrakis and pentakis phosphate esters of myo-inositol and any physiologically acceptable derivatives and salts thereof, such as alkali metal, alkaline-earth metal, ammonium salts or mixtures thereof. These phytic acid compounds may be used singly or in combination.

The phytic acid compounds which can be used in the present invention include phytic acid and metal salts of phytic acid in which all or some of the hydrogen atoms in the phosphate groups at the 1- to 6-positions of phytic acid are replaced by metal substituents, for example, alkali metal salts of phytic acid such as sodium phytate, potassium phytate and lithium phytate, ammonium phytate, divalent metal salts of phytic acid such as magnesium phytate, zinc phytate and calcium phytate, aluminium phytate and phytin, and double salts thereof. Mixtures of any of these salts are also included. Particularly preferred are those soluble in water. More preferably, the phytic acid compound is selected from the group consisting of phytic acid, sodium phytate, potassium phytate, lithium phytate, ammonium phytate and mixtures thereof.

Pharmaceutically Acceptable Carrier

The carrier for the components of the present compositions can be any vehicle suitable for use in the oral cavity. Such carriers include the usual components of toothpastes, tooth powders, prophylaxis pastes, lozenges, gums and the like and are more fully described hereinafter. Toothpastes are the preferred systems. The toothpaste can be packaged as a single product or be part of a dual or multi-phase system in which different toothpaste formulations are so packaged as to be presented as a single product upon use, such as is known in the art in e.g. striped toothpastes.

Water is usually present in the oral compositions of this invention. Water employed in the preparation of commercially suitable toothpastes should preferably be deionised and free of organic impurities. Water generally comprises from about 10% to 50%, preferably from about 20% to 40%, by weight of the toothpaste compositions herein. These amounts of water include the free water which is added plus that which is introduced with other materials such as with sorbitol. Optional components

In addition to the above described essential components, the embodiments of this invention can contain a variety of optional dentifrice ingredients some of which are described below. Optional ingredients include, for example, but are not limited to, adhesives, sudsing agents, flavouring agents, sweetening agents, additional anti-plaque agents, abrasives, and colouring agents. These and other optional components are further described in US-A-5,004,597; US-A-4,885,155; US-A-3,959,458 and US-A- 3,937,807, all being incorporated herein by reference.

Surfactants:

One of the preferred optional agents of the present invention is a surfactant.

Preferred anionic surfactants useful herein include the water-soluble salts of alkyl sulphates and alkyl ether sulphates having from 10 to 18 carbon atoms in the alkyl radical and the water-soluble salts of sulphonated monoglycerides of fatty acids having from 10 to 18 carbon atoms. Sodium lauryl sulphate and sodium coconut monoglyceride sulphonates are examples of anionic surfactants of this type. Mixtures of anionic surfactants can also be utilised.

Other useful surfactants include alkali metal or ammonium salts of sarcosinates, isethionates and taurates. Preferred herein are the sodium and potassium salts of the following: lauroyl sarcosinate, myristoyl sarcosinate, palmitoyl sarcosinate, stearoyl sarcosinate and oleoyl sarcosinate.

Other suitable compatible surfactants, which can optionally be used in combination with the surfactants above include those mentioned in US-A-3,959,458; US-A-3,937,807; and US-A-4,051,234.

The surfactant is preferably present in the compositions of the present invention at a level of from about 0.1% to about 2.5%, preferably from about 0.3% to about 2.5% and most preferably from about 0.5% to about 2.0% by weight of the total composition.

Preferred cationic surfactants useful in the present invention can be broadly defined as derivatives of aliphatic quaternary ammonium compounds having one long alkyl chain containing from about 8 to 18 carbon atoms such as lauryl trimethylammonium chloride; cetyl pyridinium chloride; benzalkonium chloride; cetyl trimethylammonium bromide; di-isobutylphenoxyethyl-dimethylbenzylammonium chloride; coconut alkyltrimethyl- ammonium nitrite; cetyl pyridinium fluoride; etc. Preferred compounds are the quaternary ammonium fluorides described in US-A-3,535,421, where said quaternary ammonium fluorides have detergent properties. Certain cationic surfactants can also act as germicides in the compositions disclosed herein. Some cationic agents such as chlorhexidine, although suitable for use in the current invention, are not preferred due to their capacity to stain the oral cavity's hard tissues. Persons skilled in the art are aware of this possibility and should incoφorate cationics only with this limitation in mind.

Preferred nonionic surfactants that can be used in the compositions of the present invention can be broadly defined as compounds produced by the condensation of alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound which may be aliphatic and/or aromatic in nature. Examples of suitable nonionic surfactants include the Pluronics, polyethylene oxide condensates of alkyl phenols, products derived from the condensation of ethylene oxide with the reaction product of propylene oxide and ethylene diamine, ethylene oxide condensates of aliphatic alcohols, long chain tertiary amine oxides, long chain tertiary phosphine oxides, long chain dialkyl sulphoxides and mixtures of such materials.

Preferred zwitterionic synthetic surfactants useful in the present invention can be broadly described as derivatives of aliphatic quaternary ammonium, phosphonium, and sulphoniurn compounds, in which the aliphatic radicals can be straight chain or branched, and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic water-solubilising group, e.g., carboxy, sulphonate, sulphate, phosphate or phosphonate.

Preferred betaine surfactants are disclosed in US-A-5, 180,577. Typical alkyl dimethyl betaines include decyl betaine or 2-(N-decyl-N,N-dimethylammonio) acetate, coco betaine, myristyl betaine, palmityl betaine, lauryl betaine, cetyl betaine, cetyl betaine, stearyl betaine, etc. The amidobetaines are exemplified by cocoamidoethyl betaine, cocoamidopropyl betaine, lauramidopropyl betaine and the like. The betaines of choice are preferably the cocoamidopropyl betaine and, more preferably, the lauramido propyl betaine.

Chelating agents:

Another preferred optional agent is a chelating agent. Preferred chelating agents are selected from tartaric acid and pharmaceutically-acceptable salts thereof, citric acid and alkali metal citrates and mixtures thereof. Chelating agents are able to complex calcium found in the cell walls of the bacteria. Chelating agents can also disrupt plaque by removing calcium from the calcium bridges which help hold this biomass intact. However, it is possible to use a chelating agent which has an affinity for calcium that is too high. This results in tooth demineralisation and is contrary to the objects and intentions of the present invention.

Sodium and potassium citrate are the preferred alkali metal citrates, with sodium citrate being the most preferred. Also preferred is a citric acid/alkali metal citrate combination. Preferred herein are alkali metal salts of tartaric acid. Most preferred for use herein are disodium tartrate, dipotassium tartrate, sodium potassium tartrate, sodium hydrogen tartrate and potassium hydrogen tartrate. The amounts of chelating agent suitable for use in the present invention are about 0.1% to about 2.5%, preferably from about 0.5% to about 2.5% and more preferably from about 1.0% to about 2.5%. The tartaric acid salt chelating agent can be used alone or in combination with other optional chelating agents.

Other optional chelating agents can be used. Preferably these chelating agents have a calcium binding constant of about 10 to 10^ provide improved cleaning with reduced plaque and calculus formation.

Another group of agents particularly suitable for use as chelating agents in the present invention are the soluble polyphosphates, polyphosphonates, and pyrophosphates which are useful as anticalculus agents. The pyrophosphate salts used in the present compositions can be any of the alkali metal pyrophosphate salts. Specific salts include terra alkali metal pyrophosphate, dialkali metal diacid pyrophosphate, trialkali metal monoacid pyrophosphate and mixtures thereof, wherein the alkali metals are preferably sodium or potassium. The salts are useful in both their hydrated and unhydrated forms. An effective amount of pyrophosphate salt useful in the present composition is generally enough to provide at least 1.0% pyrophosphate ion, preferably from about 1.5% to about 6%, more preferably from about 3.5% to about 6% of such ions. It is to be appreciated that the level of pyrophosphate ions is that capable of being provided to the composition (i.e., the theoretical amount at an appropriate pH) and that pyrophosphate forms other than P2θ7"4 (e.g., (HP2θγ^~3)) may be present when a final product pH is established. The pyrophosphate salts are described in more detail in Kirk & Othmer, Encyclopedia of Chemical Technology, Second Edition, Volume 15, Interscience Publishers (1968).

Also useful are the soluble polyphosphates such as sodium tripolyphosphate and sodium hexametaphosphate. Long chain anticalculus agents of this type are described in WO 98/22079, incoφorated herein by reference.

Still another possible group of chelating agents suitable for use in the present invention are the anionic polymeric polycarboxylates. Such materials are well known in the art, being employed in the form of their free acids or partially or preferably fully neutralised water soluble alkali metal (e.g. potassium and preferably sodium) or ammonium salts.

Preferred are 1:4 to 4:1 copolymers of maleic anhydride or acid with another polymerisable ethylenically unsaturated monomer, preferably methyl vinyl ether (methoxyethylene) having a molecular weight (MW) of about 30,000 to about 1,000,000. These copolymers are available for example as Gantrez AN 139 (MW 500,000), AN 119 (MW 250,000) and preferably S-97 Pharmaceutical Grade (MW 70,000), of GAF Chemicals Coφoration.

Other operative polymeric polycarboxylates include those such as the 1:1 copolymers of maleic anhydride with ethyl acrylate, hydroxyethyl methacrylate, N-vinyl-2-pyrollidone, or ethylene, the latter being available for example as Monsanto EMA No. 1103, MW 10,000 and EMA Grade 61, and 1:1 copolymers of acrylic acid with methyl or hydroxyethyl methacrylate, methyl or ethyl acrylate, isobutyl vinyl ether or N-vinyl-2- pyrrolidone.

Additional operative polymeric polycarboxylates are disclosed in US-A-4,138,477 to Gaffar and US-A-4,183,914 to Gaffar et al., and include copolymers of maleic anhydride with styrene, isobutylene or ethyl vinyl ether, polyacrylic, polyitaconic and polymaleic acids, and sulphoacrylic oligomers of MW as low as 1,000 available as Uniroyal ND-2.

Fluorides:

It is common to have an additional water-soluble fluoride compound present in dentifrice and other oral compositions in an amount sufficient to give a fluoride ion concentration in the composition at 25°C₅ and/or when it is used of from about 0.0025% to about 5.0% by weight, preferably from about 0.005% to about 2.0% by weight, to provide additional anticaries effectiveness. A wide variety of fluoride ion-yielding materials can be employed as sources of soluble fluoride in the present compositions. Representative fluoride ion sources include: stannous fluoride, sodium fluoride, potassium fluoride, calcium monofluorophosphate, sodium monofluorophosphate and many others. Sodium fluoride is particularly preferred.

Silicone oils

An optional ingredient in the present compositions is a silicone oil. Suitable classes of silicone oils include, but are not limited to, dimethicones, dimethiconols, dimethicone copolyols and aminoalkylsilicones, preferred silicone oils are selected from , dimethicone copolyols and aminoalkylsilicones, more preferably from dimethicone copolyols.

Suitable aminoalkylsilicones are selected from noncyclic, hydrophobic aminoalkylsilicones having a formula comprising two basic units:

1) (R )m(R)n$iO(4-m-n)/2 wherein m+n is 1, 2 or 3; n is 1, 2 or 3; m is 0,1,2; and

2) (R )a(R^)bSiO(4-a-b)/2 ^{wnereul a+D} is 1, 2, or 3, and a and b are integers, wherein R* and R^ are independently selected from H ,alkyl and alkenyl of about 1 to about 10 carbons optionally substituted with fluoro or cyano groups, hydroxy, alkoxy, and acetoxy, for example, wherein R and R^ are independently selected from methyl, ethyl, phenyl, vinyl, trifluoropropyl and cyanopropyl, and R is

wherein R- is a divalent alkylene of about 1-20, preferably about 3-5 carbon atoms optionally substituted or interrupted by O atoms, R^, R5 and R^ which may be the same or different are selected from H, alkyl of about 1-20, preferably about 1-10, more preferably about 1-4 carbons optionally substituted or interrupted by N and/or O atoms, and X" is a monovalent anion such as halide, hydroxide, and tosylate, the amino- alkylsilicone including from about 0.1 to 2%, preferably from about 0.5 to 2% of unit (1) on a repeating unit basis.

Preferred aminoalkylsilicones are amodimethicones. Amodimethicones are polydimethylsiloxane polymers containing aminoalkyl groups. The aminoalkyl groups may be present either pendant or at one or more ends of the polydimethylsiloxane chain. In preferred aminoalkylsilicones the aminoalkyl moiety R is selected from (CH2)3NH2, (CH₂)3NHCH2CH₂NH2, (CH₂)3N(CH2CH₂OH)2, (CH₂)₃NH₃ ⁺X-, and

(CH2)3N(CH₃)2(Ci8H37)⁺X-, and especially from (CH₂)3NH₂ and (CH₂)3NH- CH2CH2NH2. Also preferred are aminoalkyl silicones having an average molecular weight of about 5,000 and above, preferably from about 5000 to about 100,000, more preferably from about 5000 to about 30,000.

Methods of preparing aminoalkylsilicones are given in, for example, US-A-2,930,809. Examples of amodimethicones include OSI's Magnasoft fluid.

More preferred for use herein are alkyl- and alkoxy-dimethicone copolyols and mixtures thereof. Especially preferred are dimethicone copolyols selected from alkyl dimethicone copolyols and alkoxy dimethicone copolyols having the formula (I):

wherein X is selected from hydrogen, alkyl, alkoxy and acyl groups having from 1 to about 16 carbon atoms, Y is selected from alkyl and alkoxy groups having from about 8 to about 22 carbon atoms, n is from 0 to about 200, m is from about 1 to about 40, q is from 1 to about 100, the molecular weight of the residue (C2H4O-)_x(C3HgO-)yX is from about 50 to about 2000, preferably from about 250 to about 1000 and x and y are such that the weight ratio of oxyethylene:oxypropylene is from 100:0 to 0:100, preferably from 100:0 to about 20:80. In preferred embodiments, the dimethicone copolyol is selected from C12 to C20 alkyl dimethicone copolyols and mixtures thereof. Highly preferred is cetyl dimethicone copolyol marketed under the trade name Abil EM90.

The silicone oil is useful as an antiplaque agent and helps to prevent re-soiling of teeth. It is generally present in a level of from about 0.1% to about 15%, preferably from about 0.5% to about 5%, more preferably from about 0.5% to about 3% by weight.

Antimicrobials

Also useful for inclusion in the compositions of the present invention are antimicrobial agents. A wide variety of antimicrobial agents can be used, including stannous salts such as stannous pyrophosphate and stannous gluconate, quaternary ammonium salts, such as cetyl pyridinium chloride and tetradecylethyl pyridinium chloride, bis-biguanide salts, copper bisglycinate, nonionic antimicrobial agents and certain flavour oils such as thymol. Such agents are disclosed in U.S. Pat. No. 2,946,725, Jul. 26, 1960, to Norris et al. and U.S. Pat. No. 4,051,234, Sep. 27, 1977 to Gieske et al. Also useful is sodium chlorite, described in WO 99/43290.

Antimicrobial agents , if present, are typically included at levels of from about 0.01% to about 10%. It is preferred to keep the level of stannous and cationic antimicrobial agents to less than 5%, preferably less than 1% to avoid staining problems.

Preferred antimicrobial agents are non-cationic antimicrobial agent, such as those described in US5037637. A particularly preferred antimicrobial agent is 2',4,4'-trichloro- 2-hydroxy-diphenyl ether (triclosan).

Other components:

Flavouring agents can also be added to the present compositions. Suitable flavouring agents include oil of wintergreen, oil of peppermint, oil of spearmint, oil of sassafras, and oil of clove. Sweetening agents which can be used include aspartame, acesulphame, saccharin, dextrose, laevulose and sodium cyclamate. Flavouring and sweetening agents are generally used in dentifrice at levels of from about 0.005% to about 2% by weight.

In preparing toothpastes, it is usually necessary to add some thickening material to provide a desirable consistency and prevent precipitation of the silica. Preferred thickening agents are carboxyvinyl polymers, such as the Carbopol® series, carrageenan, hydroxethyl cellulose and water soluble salts of cellulose ethers such as sodium carboxymethyl cellulose and sodium carboxymethyl hydroxethyl cellulose. Natural gums such as gum karaya, xanthan gun, gum arabic, and gum tragacanth can also be used. Thickening agents in an amount from 0.5% to 5.0% by weight of the total composition can be used.

It is also desirable to include some humectant material in a toothpaste to keep it from hardening. Suitable humectants include glycerin, sorbitol, and other edible polyhydric alcohols at a level of from about 15% to about 70%.

Other optional components include buffering agents, bicarbonates, peroxides, nitrate salts such as sodium and potassium nitrate.

Suitable lozenge and chewing gum components are disclosed in US-A-4,083,955 and WO97/02009, both incoφorated herein by reference. The following examples further describe and demonstrate preferred embodiments within the scope of the present invention. The examples are given solely for illustration and are not to be construed as limitations of this invention.

Examples

The following are representative toothpaste formulations according to the present invention.

Example 7 is a chewing gum formulation according to the present invention.

The compositions of the present invention can be prepared by standard techniques known to those skilled in the art.

Claims

WHAT IS CLAIMED IS:

1. An oral composition comprising: a) from 1% to 95% of a low structure precipitated silica having a mean value (MV) particle size of 8 to 14 μm, an oil absoφtion of 60 to 120 cm lOO g, and a mercury intrusion (HGI) void volume of 1.0 to 4.0 cm /g; the silica, when formulated into a dentifrice, having a Pellicle Cleaning Ratio (PCR) of from 70 to 140 and a Radioactive Dentin Abrasion (RDA) value of from 60 to 130, wherein the ratio of the PCR to the RDA is at least 1.1; b) from 0.1 % to 20% of a phytic acid compound; and c) from about 0.1% to about 99% of an orally-acceptable carrier.

2. A composition according to Claim 1 wherein the silica has an RDA, when formulated into a dentifrice formulation, of from 60 to 98, a BET surface area of from 50 to 250 m^/g, a pH of 5% water slurry of from 4.0 to 8.5 and wherein smaller particles are cohesively adhered to each other by physical binding to be within said MV particle size.

3. A composition according to Claim 1 or Claim 2 wherein greater than about 2%, preferably greater than 5%, of said precipitated silica are agglomerated.

4. A composition according to any preceding claim wherein the phytic acid compound is selected from phytic acid, sodium phytate, potassium phytate, lithium phytate, ammonium phytate and mixtures thereof.

5. A composition according to any preceding claim which further comprises a fluoride ion source selected from sodium fluoride, potassium fluoride, stannous fluoride, sodium monofluorophosphate, calcium monofluorophosphate and mixtures thereof.

6. A composition according to any preceding claim which further comprises from about 0.1% to about 2.5% of a chelating agent selected from tartaric acid and pharmaceutically-acceptable salts thereof, citric acid and alkali metal citrates and mixtures thereof.

7. A composition according to any preceding claim which has a pH of from 3 to 9.

8. A composition according to any preceding claim which further comprises an anticalculus agent selected from polyphosphates, polyphosphonates, pyro- phosphates and mixtures thereof; preferably from polyphosphates, pyrophosphates and mixtures thereof, .

9. A composition according to any preceding claim which further comprises a silicone oil.

10. A composition according to Claim 9 wherein the silicone oil is a dimethicone copolyol.

11. A composition according to any preceding claim which further comprises an antimicrobial agent, preferably a non-cationic antimicrobial agent, more preferably triclosan.

12. An oral composition according to any preceding claim in the form of a toothpaste, tooth powder, prophylaxis paste, lozenge, gum, or oral gel.

13. A method for preventing or reducing stain on teeth comprising the application of a safe and effective amount of a composition according to any preceding claim to the teeth.