WO2000059460A1 - Additifs permettant de desensibiliser et de remineraliser des compositions de dentifrices - Google Patents

Additifs permettant de desensibiliser et de remineraliser des compositions de dentifrices Download PDF

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Publication number
WO2000059460A1
WO2000059460A1 PCT/US2000/009420 US0009420W WO0059460A1 WO 2000059460 A1 WO2000059460 A1 WO 2000059460A1 US 0009420 W US0009420 W US 0009420W WO 0059460 A1 WO0059460 A1 WO 0059460A1
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Prior art keywords
composition
inorganic oxide
oxide particles
dentifrice composition
dispersion
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PCT/US2000/009420
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English (en)
Inventor
Michael Vance Ernest
William Alan Welsh
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W.R. Grace & Co.-Conn.
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Application filed by W.R. Grace & Co.-Conn. filed Critical W.R. Grace & Co.-Conn.
Priority to AU42191/00A priority Critical patent/AU4219100A/en
Publication of WO2000059460A1 publication Critical patent/WO2000059460A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K8/00—Cosmetics or similar toiletry preparations
    • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
    • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
    • A61K8/25—Silicon; Compounds thereof
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K8/00—Cosmetics or similar toiletry preparations
    • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
    • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
    • A61K8/22—Peroxides; Oxygen; Ozone
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
    • A61Q11/00—Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
    • A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
    • A61K2800/41—Particular ingredients further characterized by their size
    • A61K2800/412—Microsized, i.e. having sizes between 0.1 and 100 microns

Definitions

  • This invention relates to inorganic oxide-based dentifrice additives having particle sizes that promote their deposition and retention on and within hard (enamel) and soft (dentin) oral tissues.
  • Tooth oi "dentinal hypei sensitivity” is defined as acute, localized pain in response to thermal, osmotic, tactile oi air blast stimulation of exposed dentin
  • the hydrodynamic theory is the most widely accepted explanation for dentinal sensitivity. The mechanism for this phenomena is believed to stem from flow changes in open/exposed (i.e., to the oral environment) dentin tubules (which occurs frequently with gingival recession) which mechanically stimulates nerve receptors located at the dentin-pulp junction.
  • Remineralization is a process in which calcium and phosphate are reintroduced into legions of the dentin and enamel that have reduced mineral content (i.e., deminerahzation). Reduced mineral content is typical in areas where caries and tooth decay are present. Microcracks and fissures in enamel/and or dentin surfaces can act as pathways for acidic oral fluid that contributes to canes development and weakened enamel.
  • tubulai blockage and/oi 2 Two established approaches to alleviate or reduce dentinal hypersensitivity are via 1 ) tubulai blockage and/oi 2) use of chemical agents to leduce sensory pulpal nerve activity. Credence to the effectiveness of the tubular blockage approach has been developed clinically by the use of high fluoride content topical treatment. Fluoride reacts with soluble calcium in the tubular fluids to precipitate very insoluble calcium fluoride. Such high fluoride content dentifrices are sold and recommended generally for professional use While effective, they have the very undesirable side effect of biownish tooth staining Professional topical agents which contain oxalate - -
  • the second approach is one that is now commercially practiced.
  • a number of dentifrices are marketed to provide relief from the discomfort associated with dentinal hypersensitivity
  • the inclusion of potassium and to a lessei degree strontium salts in dentifrice compositions is a typical formulating approach Potassium nitrate is most commonly employed, but it is the K + ion that in effect reduces the excitability of nerves at the pulp-dentinal junction Fluid movements in the tubules act as poweiful excitei s of nerve activity It has been shown by in vitro testing that the lole of potassium in the treatment of dentin itself is that of a modulator of nei ve excitability whereas hydraulic conductance testing shows its efficacy is foi tubulai blockage
  • a commeicially used approach to fostei leminerahzation involves the addition of adding soluble calcium and phosphate to a dentif ⁇ ce in ordei to increase the concentrations of calcium and phosphate above ambient oral fluid levels during brushing Calcium phosphate precipitates fiom these treatments, and ultimately crystallizes and foims hydroxyapatite
  • This cui rent invention is focused on the tubulai blockage mechanism and is the lesult of discovering and developing materials which aie paiticularly effective for reducing dentinal fluid flows through the deposition of said matenals on and within the dentin s uctuie.
  • paiticular inorganic oxide materials when leduced to, e.g., submicron particle sizes, which are much smaller with a far greatei population of such particles than employed in commercially available dentifrice compositions, have the ability to deposit and be retained on and within the dentin structure This results in blockage of tubulai openings which i educes the degree ofizid flow that can occui due to external stimuli such as air blast and/or temperature changes
  • These principally submicron matenals e.g., silica gels and precipitates, aie chemically compatible with the ingiedients typically foimulated into commercial dentifrice matenals Fuithermore, they can be used in conjunction with materials such as potassium nitrate that aie employed in desensitizing paste and gel type dentifrice foimulations
  • These matenals can be fuithei modified with chemical components such as calcium and/oi phosphate that aie well known as being beneficial foi leminerah
  • the particles of the invention also have poiosity such that when an aqueous dispeision of the pai tides is dried at least about 0 5 cc/g ol poie volume as measuied by BJH mtiogen poiosimetiy is fiom poies having a poie size oi 600A oi smallei Silica particles, and especially piecipitated silica and silica gel pai tides aie mournrred Especially pieferred pai tides have a median paiticle size in the range of 0 05 to about 1 macon
  • the composition can be in the foim of a dispeision oi sluny of the pai
  • Figuie 1 illustrates the diffusion test cell foi dentin disks
  • Figuie 2 illustiates the appaiatus foi testing hydiauhc conductance
  • Figuie 3 illusti tes a blushing machine and closei pei spective of the test cell illustrated in Figuie 1
  • Figuie 4 illustrates the particle size distribution of a feed dispeision used to make the invention
  • Figuie 5 illustrates the paiticle size dist ⁇ bution of the feed dispeision in Figure
  • Figuie 6 illustiates the paiticle size dist ⁇ bution of a dispeision accoiding to the invention which was piepaied by cent ⁇ fuging the dispeision of Figure 5
  • Figure 7 illustrates the paiticle size dist ⁇ bution of anothei feed dispersion used to make the invention
  • Figure 8 illustrates the particle size distribution of the feed dispersion in Figure 7 after that dispersion has been milled.
  • Figure 9 illustrates the particle size dist ⁇ bution oi a dispersion according to this invention which was prepared by cent ⁇ fuging the dispersion of Figure 8
  • Figure 10 is a low magnification scanning electron micrograph (SEM) of dental surfaces (dental disk) which have been treated with the invention, as well as surfaces which have been untreated.
  • Figure 1 1 is a SEM/EDS representation of surfaces treated with invention.
  • Figure 12 is a graph of — versus mass traction solids ioi several inorganic
  • ⁇ is the viscosity of the dispeisions illustrated and ⁇ ⁇ ) is the viscosity of water
  • Inorganic oxides suitable tor piepa ⁇ ng the invention include precipitated inorganic oxides and lnoigamc oxide gels These inorganic oxides are referred to herein as “parent inorganic oxides," “parent particles” oi “parent dispersions” Amorphous piecipitated silica and silica gels are particularly suitable parent inorganic oxides
  • the dispersion can also be prepared from mixed inorganic oxides including
  • the dispersions are derived from porous inorganic oxide gels such as, but not limited to, gels comprising S ⁇ 0 2 , Al 2 O , AlPO ⁇ , MgO, T ⁇ 0 2 , and Z ⁇ 0 2 Calcium phosphate gels are also suitable
  • the gels can be hydrogels, aerogels, or xerogels.
  • a hydrogel is also known as an aquagel which is formed in water and as a result its pores are filled with water.
  • a xerogel is a hydrogel with the water removed
  • An aerogel is a type of xeiogel from which the liquid has been removed in such a way as to minimize any collapse or change in the gel's structure as the watei is lemoved
  • Silica gels commercially available as Syloid® grade gels, e.g., grades 74, 221 , 234, 244, W300, W500 and Genesis 1 M silica gels are suitable parent inorganic oxides
  • Gels are well known in the ait. See Ilei's "The Chemistry of Silica", p. 462 ( 1979).
  • Gel e.g. silica gel, particles aie distinguishable from colloidal silica oi precipitated silica particles.
  • colloidal silica is piepared as a slurry of dense, non-porous silica particles.
  • Colloidal silica particles typically are smaller than 200nm (0.2 micron). As mentioned earlier, these particles do not have internal porosity.
  • typical dispersed precipitated particles have some internal poiosity
  • the internal porosity in typically precipitated particles largely collapse undei capillary piessure cieated by receding menisci of water as the water evaporates during drying
  • the conditions for making colloidal silica and precipitated silica are well known.
  • Gels are prepared under conditions which promote coalescence of primary particles (typically having median particles sizes of 1 to l Onm, as measured under transmission electron microscopy, i.e., TEM) to form a relatively ngid three dimensional network
  • primary particles typically having median particles sizes of 1 to l Onm, as measured under transmission electron microscopy, i.e., TEM
  • the coalescence of gel is exhibited on a macioscale when a dispersion of inorganic oxide, e g., silica, hardens to a "gel” oi "gelled” mass having structural integrity
  • a silica gel is prepared by mixing an aqueous solution of an alkali metal silicate (e.g , sodium silicate) with a strong acid such as nitric or sulfu ⁇ c acid, the mixing being done undei suitable conditions of agitation to form a clear silica sol which sets into a hydrogel, i.e , maciogel, in less than about one-half hour. The lesulting gel is then washed.
  • an alkali metal silicate e.g , sodium silicate
  • a strong acid such as nitric or sulfu ⁇ c acid
  • the concentration of inorganic oxide, i.e., S ⁇ 0 2 , iormed in the hydrogel is usually in the range of about 10 and about 50, preferably between about 20 and about 35, and most preferably between about 30 and about 35 weight percent, with the pH of that gel being from about 1 to about 9, preferably 1 to about 4.
  • a wide range oi mixing temperatuies can be employed, this range being typically from about 20 to about 50°C
  • the newly formed hydrogels are washed simply by immersion in a continuously moving stream of watei which leaches out the undesirable salts, leaving about 99.5 weight percent or more pure inorganic oxide behind
  • the pH, temperature, and duration of the wash water will influence the physical properties of the silica, such as surface area (SA) and pore volume (PV)
  • Silica gel washed at 65-90°C at pH's of 8-9 for 15-36 houis will usually have SA's of 250-400 and form aerogels with PV's of 1 4 to 1 7 cc/gm.
  • Silica gel washed at pH's of 3-5 at 50-65°C for 15-25 hours will have SA's of 700-850 and form aerogels with PV's of 0 6- 1.3
  • N 2 poiosity analysis Methods for preparing inorganic oxide gels such as alumina and mixed inorganic oxide gels such as silica/alumina cogels aie also well known in the ait. Methods for preparing such gels aie disclosed in U S Patents 4,226,743, the contents oi which are incorporated by reference.
  • alumina gels are prepared by mixing alkali metal aluminates and aluminum sulfate Cogels aie prepared by cogellmg two metal oxides so that the gels are composited togethei.
  • silica alumina cogels can be prepared by gelling an alkali metal silicate with an acid or acid salt, and then adding alkali metal aluminate, aging the mixture and subsequently adding aluminum sulfate The gel is then washed using conventional techniques
  • Another embodiment of this invention is derived irom dispersions of DCtain piecipitated inorganic oxides. For example, milling certain precipitated silicas results in dispersions having the porosity properties described latei below
  • Reinforced precipitated silica such as that described in U.S. Patent 4, 157,920 can also be used to prepare the dispersion of this invention
  • reinfoiced precipitated silicas can be prepared by fust acidulating an alkali inoiganic silicate to create an initial precipitate.
  • the lesulting piecipitate is then leinfoiced or "post conditioned" by additional silicate and acid
  • the piecipitate lesulting from the second addition of silicate and acid comprises 10 to 70% by weight of the precipitate initially prepared.
  • the leinforced structure of this piecipitate is moie rigid than conventional precipitates as a result of the second precipitation It is believed that even after milling, cent ⁇ fuging and subsequent drying, the reinforced silicate substantially maintains its netwoik rigidity and poiosity. This is in contrast to othei precipitated silicas such as those disclosed in U.S Patent 5,030,286.
  • suitable inorganic oxides include amorphous silica derived from natural occurring deposits such as diatomaceous earth and biogenic silicas such as that prepared from rice hulls.
  • a liquid phase of the selected inoiganic oxide is prepared
  • the medium foi the liquid phase can be aqueous oi some other medium
  • These othei mediums include watei miscible liquids in which the final dispeision is used. These mediums are described latei on
  • the liquid phase for example, can be residual water in inorganic oxide gels which have been drained, but not yet dried, and to which additional water is added to reslurry the gel.
  • dried inorganic oxides e.g., xerogels, are dispersed in liquid medium.
  • the parent dispersion should be in a state that can be wet milled.
  • the pai ent dispersion has a median particle size approximately in the uinge of 10 to 40 microns
  • the size of the parent particles only needs to be sufficient such that the mill being used can produce a dispersion having the desired median particle size at about or below 3 microns.
  • the drained gel may first be broken up into gel chunks and premilled to produce a dispersion of particles in the range of 10 to 40 microns.
  • the parent dispersion is then milled.
  • the milling is conducted "wet", i.e., in liquid media.
  • the general milling conditions can vary depending on the feed material, residence time, impeller speeds, and milling media particle size. Suitable conditions and residence times are described in the Examples. These conditions can be varied to obtain the desired size within the range of 0.05 to about 3 microns.
  • the techniques for selecting and modifying these conditions to obtain the desired dispersions are known to those skilled in the art
  • the milling equipment used to mill the parent inorganic oxide particles should be oi the type capable of severely milling and reducing matenals to particles having sizes about three microns or smaller, particularly below one micron, e.g., through mechanical action.
  • Such mills are commercially available, with hammer and sand mills being particularly suitable for this purpose.
  • Hammer mills impart the necessary mechanical action through high speed metal blades
  • sand mills impart the action through rapidly churning media such as zuconia or sand beads
  • Impact mills can also be used Both impact mills and hammei mills reduce paiticle size by impact of the inorganic oxide with metal blades A dispeision comp ⁇ sing particles of thiee micions or smallei is then tecovered as the final pioduct
  • the milled dispersion is processed to separate the dispersion into a supernatant phase, which comprises the pai tides oi the final product, and a settled phase which comprises the larger particles
  • the separation can be created by cent ⁇ tuging the milled inorganic oxide particles.
  • the supernatant phase is then removed from the settled phase, e.g., by decanting
  • the supernatant is the dispersion of this invention
  • Conventional centrifuges can be used for this phase separation.
  • the supernatant may be pieferable to centrifuge the supernatant two, three or moie times to fuithei remove large particles remaining after the initial centrifuge. It is also contemplated that the laigei particles of a milled dispersion can separate ovei time under normal gi avity conditions, and the supernatant can be removed by decanting.
  • the settled phase also can be regarded as the particles of this invention.
  • the settled phase can be removed and ledispersed.
  • the pended dispersion may need to be milled more than once to insuie that the settled phase has the appropriate particle size in the range of 0.05 to 3 micions
  • the dispersion oi particles also can be modified after milling to insure a stable dispeision.
  • dispersions can also be stabilized in certain instances by employing water miscible liquids as the dispersing medium or exchange the water with a water miscible liquid.
  • the median particle size, i.e , particle diametei . of the particles in the dispersion is in the l ange of 0 05 to about 3 microns
  • the size is p ⁇ ma ⁇ ly dictated by the dispersion's use and can be in ranges of, e g . between 0 06 to 2 9, 0 07 to 2 8, and so on
  • the median particle size is measuied using conventional light scattering instrumentation and methods The sizes lepoi ted in the Examples were determined by a LA900 lasei scattering particle size analyzei from Ho ⁇ ba Instruments, Inc
  • the solids content of the dispersion vanes can be in the l ange of 1 -30% by weight, and all l anges in between It also may be as low as 0.5% by weight
  • a solids content in the l ange of 10 to 20% by weight is suitable foi a number of applications
  • the dispeision's viscosity should be such that the dispersion is a pumpable liquid
  • the viscosity of the dispersion is highly dependent upon the dispersion's solids content and the poiosity of the particles
  • the viscosity of the dispersion's liquid phase and the completeness of the dispersion can also affect the oveiall dispersion
  • Embodiments prepared from silica gel genei ally have viscosities similai to the viscosities of the parent silica dispersion.
  • Foi example when pended silica gel is milled at a pi escribed pH in the range of 9- 10, e.g , 9 5, the viscosity of the milled silica lemains lelatively unchanged This is distinguishable from viscosities oi milled precipitated silicas The viscosities of milled piecipitated silica are less than the viscosity oi the pending material
  • the pH of the dispersion depends upon the inorganic oxide and additives used to stabilize the dispersion
  • the pH can be in the l ange of 2 to 1 1 . and all ranges in between
  • dispersions of alumina geneially have a pH in the range of 2 to 6
  • the pH can also be modif ied using conventional pH modifiei s
  • the dispei sion is lelatively fiee of impui ities when compared to embodiments compi ising, foi example, piecipitated inoiganic oxide particles
  • Pending silica gels are typically washed to lemove substantially all impurities
  • the alkali salt content of gels are typically as low as 100 ppm by weight and generally no more than 0 1 % based on the weight of gel
  • the low impurity levels of silica gels aie especially advantageous when colloidally stable dispei sions oi pai tides aie desn ed
  • the poie volume of the pai tides in dispei sion can be measuied by mtiogen poi osnneti y aftei the dispei sion is d ⁇ ed
  • at least about 0 5 cc/g of the pai tides poie volume is fiom poies having
  • the poiosity of the pai tides piovides a mechanism foi cairying additional beneficial additives conventionally used in dental and oial caie pioducts
  • the porosity in silica gel embodiments provide a pioduct having a consistent pore volume that does not leadily collapse
  • the poiosity of the pai tides in this invention can also be def ined as a viscosity de ⁇ ved poi e volume
  • Figuie 12 shows that as loadings of poious paiticles incieases, viscosity (r] ) ⁇ nc ⁇ eases in such a manner that a linear relationship is obtained when — - is plotted against a ⁇ certain range of particle loadings.
  • 77 0 is the viscosity of the dispersion's solvent, i.e., water.
  • slope for the curve shown increases as the porosity of particles increases.
  • a "viscosity derived pore volume" for the inventive particles thus can be calculated from the slope of these curves.
  • 77 0 is the viscosity of the fluid in which the particles are dispersed
  • ⁇ is the volume fraction of the suspension occupied by the particles
  • a is the "intrinsic viscosity" (equal to 2.5 for spherical, or very low aspect ratio, uncharged particles)
  • b is the volume fraction at which the viscosity becomes infinite.
  • a relationship (2) also exists between ⁇ and the mass loading (A-) of particles in the suspension expressed as a mass fraction, and the particles skeletal density
  • Viscosity data foi a system of well dispersed particles can then be plotted in the form
  • a dispersion of selected inorganic oxide is milled at one liter per minute and cent ⁇ fuged for thirty minutes at 600 g or at 2,000 g.
  • ⁇ loading (x) is determined using conventional techniques and ESL is calculated from the following equation.
  • Silica dispersions of this invention show curves having an absolute slope of about 2 40 or greater, and generally in the range of 2 4 to 10.0. This data generally translates into dispersions having viscosity de ⁇ ved pore volumes (PVa' s) of at least about 0.5cc/g Pieferred embodiments have a slope in the range of 3 50 - 5.0 and prefe ⁇ ed PVa % of about 1 0 to about 1 5 cc/g
  • the stability of the porosity in the dispersed particles of this invention is evidenced by calculating the loss in pore volume after the dispersion is d ⁇ ed As stated eai hei , poiosity in aqueous dispersed pai tides comprising less rigid networks of primary particles can be significantly reduced as water evaporates from the dispersion Comparing the dispersion's PVa and the pore volume measured after the dispersion is dried shows that at least 40% of the PVa is maintained tor dispersions of this invention Ceitain embodiments show that at least about 60% of the pore volume is maintained.
  • the invention can comprise the dispersion as is pioduced by milling and cent ⁇ fuging
  • the slurry or dispersion can be aqueous or in some other medium.
  • Suitable mediums include water miscible liquids such as those typically used to make dentifrice compositions
  • Suitable mediums include sorbitol and glycerin
  • the median particle size of the slurry or dispersion is in the iange of about 0 05 microns to about 3 microns, but can also be in the range of 0 05 to 2 microns or 0.05 to 1 micron
  • Particulai embodiments described below have a median particle size in the range of 0.2 to 1 .0 micron or 0.2 to 0.8 micron, with a standard deviation in the range of 0.2 to 0 8 micron
  • These pai ticle sizes are repoited in conventional volume-based statistics Without being held to a particular theory, it is believed that the pai ticle sizes of the invention are the same as oi smaller than the diameters of the tubular openings on the dentinal surface.
  • the particles of the invention deposit and otherwise become anchored to the surfaces of the enamel and dentin fissures and microcracks mentioned earlier.
  • the inorganic particles can then act as a host foi calcium phosphate precipitation and subsequent crystallization and formation of hydroxyapatite
  • the solids content of the dispersion can be in the l ange of 0.5 to 30% by weight. Howevei , the solids content can vai y depending on the medium in which the particles are dispersed and the viscosity desired for the dispersion. The solids content also depends on the amounts of inorganic oxide needed to effect desensitization and/or remineralization.
  • calcium and/or phosphate can be combined with, oi incorporated into inoiganic oxide particles of this invention to enhance remineralization as a result of calcium phosphate piecipitation it the site of deposition oi said inoi ganic oxide particles.
  • the calcium and/or phosphate can be added by co-milling calcium and/or phosphate salts along with the inorganic oxide, or in a specific embodiment co-milling amorphous forms of calcium and/or phosphate
  • the calcium and/or phosphate can also be mixed with the dispei sion oi inorganic oxide pai tides after the particles have been milled and cent ⁇ f uged Adding calcium and/or phosphate to the porous pai tides oi the invention allows the calcium and/oi phosphate to be incorporated within the porous structui e of the particles Then, upon deposition of the invention onto and/or within the dentinal tubular openings, the calcium and/or phosphate are delivered to and undergo piecipitation at the same site Upon
  • Conventional dentifrice foimulations comprise humectants, abrasives, and additives such as flavors, anti-canes additives and the like Additional examples of dental additives aie potassium nitrate and strontium chloride added for desensitization
  • dental additives aie potassium nitrate and strontium chloride added for desensitization
  • anti-microbial agents aie t ⁇ closan, cetylpy ⁇ dinium chloride (CPC), chlorhexidene, 13G (aldyl dimethyl betamine, dimethyl alkylamine oxide, sodium fluoride) and methyl paiaben
  • anti-miciobial agents include metal salts such as zinc
  • the particles can be added to the dentifrice as a dispersion prepared using the methods above.
  • the pai tides of the afoiementioned dispeision can be added so that the pai tides are a pait of oi in addition to any inoiganic abi asives employed in the dentifi ice
  • Dental abrasives typically have median pai tides sizes in the l ange of 8-20 microns and geneially make up 10 to 30% by weight of the dentifi ice
  • the lemaimng balance of the dentifrice comprises humectants such as soi bitol oi glycerin, tieatment additives such as the va ⁇ ous forms of fluoride, colorants, and the like
  • the aforementioned dispersion would be added so that the particles of the dispersion is a distinct portion of the dentifiice which comprises 0 5 to about 15% by weight of the dentifi ice
  • a dentifi ice accoiding to this invention comprises a population of particles which is believed to be unique compaied to conventional abiasive-containing dentif ⁇ ces
  • the dentifrice of this invention comprises 0 5 to 15% by weight of poious inorganic particles having a median particle size in the range of 0.05 to 3 microns
  • the dentif ⁇ ce comprises 2- 10% by weight of porous inoi ganic pai tides having a median particle size in the tange of 0 05 to 2 micions, and even more preferably a median particle size of 0.5 to 1.0 micron.
  • the size of particles per this invention can also be characterized as preferably having a mean particle size in the range of 0.2 to 1.0 micron and having a standard deviation in the range of 0.2 to 0.8 micron
  • the pH of the dentifrice would be that of conventional dentifrices and could be different over the pH of the invention comp ⁇ sing the dispeision per se
  • the pH of typical dentif ⁇ ces e.g., a toothpaste
  • the dispersion per se would be more in the range of 8- 10 and could be modified just prior to use to have a pH in the range of 5.5 to 8 This modification could be effected by mixing the dispersion with a pH modifying component
  • pai t comprises the dispei sion pei se and the other comprises a pH modifier such as monobasic potassium phosphate oi monobasic sodium phosphate
  • a pH modifier such as monobasic potassium phosphate oi monobasic sodium phosphate
  • the pH modifiei is selected to modify the pH of the invention in order to produce a product which is safe, e.g., neutral, foi contact with oral tissue, as well as produce a compatible environment for other oral caie additives, such as fluoride
  • Human molars (typically unerupted thud molars) are used as sources of dentin foi in vitro flow measuiement commonly iefe ⁇ ed to as hydraulic conductance testing Disks of approximately 0 7- 1 millimeter in thickness are prepared by cutting the tooth using a saw (such as a Buehler Isomet low speed saw) with diamond containing wafe ⁇ ng blade
  • a saw such as a Buehler Isomet low speed saw
  • the occlusal suiface (ci own side) of a selected (based on coloi , lack of obvious caries or fillings) tooth is bonded using a commercial epoxy resin system to a short length of aluminum lod
  • the aluminum rod serves to provide a secure mount in the saw
  • the fust cut is made parallel to the occlusal suiface and lemoves the root Ideally that cut will be at the pulp-dentin junction with the pulp removed by saw keif.
  • the smeai layei is basically the cutting and sanding debris that remains on the dentin sin faces This smeai layei causes plugging of at least some of the tubulai openings which manifests itself in leduced fluid flows compared to the possible fluid flows with all the tubules open Most common piactice in studying the effect of materials on tubular blockage is to remove the smeai layer before such testing This is typically accomplished by acid etching.
  • Phosphoric, boric and citric acids are commonly used for smear layei removal
  • a 15 second etch with 37% phosphoric acid, followed by copious flush with watei is employed as a standard smeai layei lemoval tieatment
  • Hydraulic conductance testing measures the rate of fluid flow thiough the dentin disks prepared and conditioned as discussed above.
  • the key equipment used to test the late of fluid flow through dentin specimens, specifically dentin disks is the same as that reported in the journal hteratuie and is what is commonly known as a
  • Pashley permeability test cell (puichased commercially from Kenward Company oi North Augusta, South Caiohna).
  • the conditioned dentin disk is mounted in the test cell (see Figuie 1 ) in such an orientation that the flow direction will be through (in) the pulp side of the disk to (out) the crown side of the disk. That orientation is used for all testing to be described herein.
  • Distilled water is used as the test fluid in the examples to follow.
  • Ten psig of fluid pressure is applied to the test cell.
  • the flow rate is determined by measuring the linear movement of a bubble in a capillary tube of established volume/length ratio (both 25 ⁇ l/65mm and 100 ⁇ l/ l 15mm capillaries sizes are used) See Figure 2 for photo of test equipment.
  • Hydraulic conductance is defined as the volume flow rate pei unit time per unit cross-sectional flow area pei unit hydiostatic water pressuie
  • the units of measure will only be reported as microliters per minute per cm of watei pei squaie centimetei (cm) oi cross-sectional area
  • the nominal cross-sectional flow area is 0 157cm " Because dentin is variable from tooth to tooth, lephcate testing is conducted with each dentin specimen used as its own control. Multiple readings aie taken aftei each specific treatment
  • Hydraulic conductance testing measures how the flow characteristics vary as the dentin disks aie treated with matenals (e g., silica slui ⁇ es, toothpaste) of varying properties (chemical as well as physical)
  • matenals e g., silica slui ⁇ es, toothpaste
  • properties chemical as well as physical
  • the device requires the samples to be dried. Where drying was carried out, it was done so in vacuo at ambient temperature. Once dried the dentin disks are prepared and examined via conventional SEM and EDS imaging techniques. Care is taken to be certain that the orientation (that is, the pulpal and occlusal sides) can be related to the side that has been exposed directly to the treatment materials.
  • Example 1 This example describes preparing an embodiment of this invention from a silica gel. Furthermore, the submicron particles of silica produced are sufficiently small enough to penetrate into the tubular openings.
  • Syloid® W500 A commercially available silica gel powder known as Syloid® W500 was used as the silica source in preparing the submicron silica dispersion.
  • Syloid W500 has a solids content of 47% by weight as measured using an Ohaus moisture determination balance model 6010. Particle size distribution measured using a Horiba LA900 laser diffraction analyzer is shown in Figure 4 which shows the absence of submicron particles. Median particle size is 7.64 microns (measured after 2 minutes ultrasonication).
  • a 20% solids slurry was prepared by high shear dispersing 1063.8 gra s Syloid W500 into 1436.2 grams deionized water. The resultant slurry was introduced into a Netzsch LabStar Type LS- 1 Zeta media mill. The silica slurry was milled for 45 minutes producing a slurry with reduced particle size as shown in Figure
  • Example 1 B-S dispersion at 8% solids and pH ⁇ 9 to be known as Example 1 B-S
  • Example 1 A-S dispersion at 12% solids and pH ⁇ 9 to be known as Example 1 A-S
  • Example 1 P-S monobasic potassium phosphate solution to be known as Example 1 P-S
  • Example 2 The example desc ⁇ bes the pieparation of anothei submicron silica dispeision that exhibits effectiveness for reducing dentin fluid flows
  • a size reduced silica hydrogel was used as the silica source in preparing submicron silica gel dispersions for this example.
  • the silica gel has a solids content oi 47.2% by weight as measured using an Ohaus moisture determination balance model 6010 Particle size distribution measured using a Horiba LA900 lasei diffi action analyzei is shown in Figuie 7 Median particle size is 8.89 microns
  • Example 3 Hydraulic conductance testing was cai ⁇ ed out on three separate dentin disks employing the test protocol discussed eaihei .
  • the data are summarized in Table I
  • the silica dispersion identified as Example IB-S was used in the three test runs The data show this silica dispersion is quite effective foi I educing hydraulic conductance
  • Example 4 Hydraulic conductance testing was carried out on three separate dentin disks employing the test protocol as discussed eaihei The data aie summarized in Table 2
  • silica dispersion identified as Example 1 A-S/ 1 P-S mix was used in the three test runs
  • Freshly mixed dispersions weie employed foi each brushing tieatment The data show this silica dispeision is quite effective foi i educing hydiaulic conductance
  • Example 6 To illustrate the ineffectiveness foi hydraulic conductance reduction, a silica (a silica source as used for dispersions piepared in Example 1 ) having a particle size typical of silicas employed as a dentif ⁇ ce abrasive was dispei sed in deionized water to form an 8%> solids content slu ⁇ y This dispersion was then employed in the bl ushing treatments in triplicate testing of separate dentin disks. The data are summarized in Table 4. The data show treatment with conventionally sized silica is generally ineffective for reducing hydraulic conductance.
  • SEM data are shown in Figure 10 of the occlusal (side) surface which shows how the silica has coated the dentin where it has come in contact.
  • the dentin disk had been removed from the test cell after run 19 (see Table 2) was completed.
  • the dentin disk was vacuum dried at ambient temperature.
  • SEM imaging of the pulpal (side) surface shown in Figure 1 1 indicates that the submicron silica has penetrated through the tubules.
  • the presence of silica had been established via EDS analysis of selected areas on the pulpal side of the dentin disk which had not had direct contact with the silica dispersion.

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Abstract

L'invention concerne une composition et un procédé permettant de désensibiliser et de reminéraliser des surfaces dentinaires et/ou d'émail. Ce procédé consiste à placer en contact une surface dentinaire avec des particules d'oxyde inorganique dont la taille particulaire moyenne est de l'ordre du sous-micron, mais qui peut être comprise entre 0,05 et 3 microns. Ces particules sont, de préférence, poreuses et présentent une porosité d'au moins 0,5 cc/g lors de leur mesure à partir d'une dispersion séchée de particules d'oxyde inorganiques. Cette composition peut être appliquée sous forme d'une dispersion particulaire aqueuse ou miscible avec l'eau. Ces particules peuvent également être placées dans une pâte dentifrice traditionnelle contenant des abrasifs d'oxydes inorganiques traditionnels. Le gel de silice et la silice précipitée constituent des exemples de matériaux d'oxydes inorganiques particulièrement appropriés pour la présente invention.
PCT/US2000/009420 1999-04-07 2000-04-07 Additifs permettant de desensibiliser et de remineraliser des compositions de dentifrices WO2000059460A1 (fr)

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Cited By (9)

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WO2008040723A1 (fr) 2006-10-04 2008-04-10 Fritz Ley Composition dentaire, en particulier reminéralisante et efficace contre les dents sensibles, ainsi que particules dentaires, en particulier pour la composition
EP2070541A1 (fr) * 2006-09-21 2009-06-17 Toshiki Oguro Promoteur de régénération des tissus durs
WO2011123121A1 (fr) * 2010-03-31 2011-10-06 Colgate-Palmolive Company Composition de soin buccal
WO2011123123A1 (fr) * 2010-03-31 2011-10-06 Colgate-Palmolive Company Composition de soins bucco-dentaires
DE102013004088A1 (de) * 2013-03-11 2014-09-11 Voco Gmbh Besonders lagerstabile und thixotrop standfeste Prophylaxepaste für den professionellen zahnärztlichen Gebrauch
JP2015535924A (ja) * 2012-08-31 2015-12-17 ジョンソン・アンド・ジョンソン・コンシューマー・カンパニーズ・インコーポレイテッドＪｏｈｎｓｏｎ ＆ Ｊｏｈｎｓｏｎ ＣｏｎｓｕｍｅｒＣｏｍｐａｎｉｅｓ，Ｉｎｃ． 透過性フローセル及び水力学的コンダクタンスシステム
JP2016500150A (ja) * 2012-08-31 2016-01-07 ジョンソン・アンド・ジョンソン・コンシューマー・カンパニーズ・インコーポレイテッドＪｏｈｎｓｏｎ ＆ Ｊｏｈｎｓｏｎ ＣｏｎｓｕｍｅｒＣｏｍｐａｎｉｅｓ，Ｉｎｃ． 透過性フローセル及び水力学的コンダクタンスシステム
US9927422B2 (en) 2014-05-13 2018-03-27 The Procter & Gamble Company Method and device for measuring dentin permeability
WO2021236910A1 (fr) * 2020-05-20 2021-11-25 The Regents Of The University Of California Compositions pour le traitement de taches blanches dentaires

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EP2070541A1 (fr) * 2006-09-21 2009-06-17 Toshiki Oguro Promoteur de régénération des tissus durs
CN101573127A (zh) * 2006-09-21 2009-11-04 大黑俊树 硬组织再生促进剂
JPWO2008035816A1 (ja) * 2006-09-21 2010-01-28 俊樹 大黒 硬組織再生促進剤
US20100143488A1 (en) * 2006-09-21 2010-06-10 Toshiki Oguro Promoter of hard tissue regeneration
EP2070541A4 (fr) * 2006-09-21 2011-04-13 Toshiki Oguro Promoteur de régénération des tissus durs
JP5557448B2 (ja) * 2006-09-21 2014-07-23 俊樹 大黒 硬組織再生促進剤
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WO2008040723A1 (fr) 2006-10-04 2008-04-10 Fritz Ley Composition dentaire, en particulier reminéralisante et efficace contre les dents sensibles, ainsi que particules dentaires, en particulier pour la composition
WO2011123121A1 (fr) * 2010-03-31 2011-10-06 Colgate-Palmolive Company Composition de soin buccal
US10441516B2 (en) 2010-03-31 2019-10-15 Colgate-Palmolive Company Oral care composition
CN102811698A (zh) * 2010-03-31 2012-12-05 高露洁-棕榄公司 口腔护理组合物
US8652495B2 (en) 2010-03-31 2014-02-18 Colgate-Palmolive Company Oral care composition
WO2011123123A1 (fr) * 2010-03-31 2011-10-06 Colgate-Palmolive Company Composition de soins bucco-dentaires
US11628128B2 (en) 2010-03-31 2023-04-18 Colgate-Palmolive Company Oral care composition
US11103431B2 (en) 2010-03-31 2021-08-31 Colgate-Palmolive Company Oral care composition
CN102821739A (zh) * 2010-03-31 2012-12-12 高露洁-棕榄公司 口腔护理组合物
US9320699B2 (en) 2010-03-31 2016-04-26 Colgate-Palmolive Company Oral care composition
US9532932B2 (en) 2010-03-31 2017-01-03 Colgate-Palmolive Company Oral care composition
US9883995B2 (en) 2010-03-31 2018-02-06 Colgate-Palmolive Company Oral care composition
JP2016500150A (ja) * 2012-08-31 2016-01-07 ジョンソン・アンド・ジョンソン・コンシューマー・カンパニーズ・インコーポレイテッドＪｏｈｎｓｏｎ ＆ Ｊｏｈｎｓｏｎ ＣｏｎｓｕｍｅｒＣｏｍｐａｎｉｅｓ，Ｉｎｃ． 透過性フローセル及び水力学的コンダクタンスシステム
JP2015535924A (ja) * 2012-08-31 2015-12-17 ジョンソン・アンド・ジョンソン・コンシューマー・カンパニーズ・インコーポレイテッドＪｏｈｎｓｏｎ ＆ Ｊｏｈｎｓｏｎ ＣｏｎｓｕｍｅｒＣｏｍｐａｎｉｅｓ，Ｉｎｃ． 透過性フローセル及び水力学的コンダクタンスシステム
US10299997B2 (en) 2013-03-11 2019-05-28 Voco Gmbh Particularly storage-stable and thixotropically stable prophylaxis paste for professional dental use
DE102013004088A1 (de) * 2013-03-11 2014-09-11 Voco Gmbh Besonders lagerstabile und thixotrop standfeste Prophylaxepaste für den professionellen zahnärztlichen Gebrauch
US9927422B2 (en) 2014-05-13 2018-03-27 The Procter & Gamble Company Method and device for measuring dentin permeability
WO2021236910A1 (fr) * 2020-05-20 2021-11-25 The Regents Of The University Of California Compositions pour le traitement de taches blanches dentaires

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