Abstract:
The method of the present invention is directed to the storage and dispensing of a peroxide containing tooth whitening composition. During storage and subsequent use the composition in the storage chamber must be maintained segregated from the applicator surface. This is accomplished by delivering the peroxide containing tooth whitening composition from the storage chamber through a delivery channel having a length and a cross-sectional diameter sufficient to preclude the migration of moisture and the enzyme catalase from the application surface to the storage chamber. The composition is applied to teeth by means of bristles, a sponge surface or fibrillated surface. This applicator can be used with both aqueous and non-aqueous peroxide containing tooth whitening compositions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a divisional of U.S. application Ser. No. 11/403,732, filed Apr. 13, 2006, now allowed, which is a continuation of International Application No. PCT/US04/33502, filed Oct. 12, 2004, which claims priority from U.S. Provisional Application No. 60/511,020, filed Oct. 14, 2003, all of which are incorporated by reference herein in their entirety. 
    
    
     FIELD OF INVENTION 
     This invention is directed to a method of applying a tooth whitening composition to teeth and an applicator to be used in this method. 
     BACKGROUND 
     Tooth whitening products are applied in different ways. A common technique is to cast an impression of a person&#39;s teeth and provide a tray of the shape of this impression. A person then only needs to add a whitening composition to the tray and to apply the tray to his/her teeth. This is left in place for a period of time and then removed. After a few treatments the teeth gradually whiten. Another technique is to use a strip that has a whitening composition on one surface. This strip is applied to a person&#39;s teeth and left in place for about 30 minutes. After several applications the teeth are gradually whitened. Yet another technique is to apply a whitening composition to teeth using a small brush. This brush is repeatedly dipped back into the container during the application of the tooth whitening composition to ones teeth. After a few treatments the teeth gradually whiten. 
     A problem with the latter technique is that saliva in the mouth contains the enzyme catalase. This enzyme will catalize the decomposition of peroxides. The brush can pick up some catalase during the application of some of the whitening product to teeth and transport that catalase back to the bottle. This catalase now in the bottle can degrade the peroxide in the bottle. Another problem with this latter technique is that it does not adapt for use with anhydrous whitening compositions. Here the brush may transport moisture from saliva from the mouth back into the bottle. This will have a negative affect on the whitening composition by potentially decomposing the peroxide active ingredient. In addition if a person washes the brush each time after use moisture from the wet bristles can enter the bottle. 
     These problems require a better way to deliver the whitening composition to the teeth. The objective is to maintain the supply of whitening composition segregated from the general environment and from mouth saliva. This objective has to be fulfilled using a dispenser that is easy to use by a person to apply the whitening composition to his/her teeth and is gentle on the teeth and gums. Additionally in a preferred embodiment the dispenser should be readily portable. 
     The present invention addresses and solves these problems. Preferred dispensers are elongated and pen-like in shape. They can contain about 0.5 ml to 20 ml of a product in the body portion and they have an applicator end for applying the contained tooth whitening compositions to a person&#39;s teeth. The applicator end is constructed such that moisture and saliva components will not migrate from an applicator surface into the part of the dispenser where the whitening composition is stored. In addition the applicator components must be compatible with the whitening compositions. 
     BRIEF SUMMARY 
     This invention comprises a method for applying a tooth whitening composition to a persons teeth, and in one preferred embodiment an anhydrous tooth whitening composition. This latter composition must be maintained substantially anhydrous prior to an application to a persons teeth. In addition all compositions must be maintained free from catalase contamination during use. This requires a dispenser that is to be used for multiple treatments to maintain the stored whitening composition substantially segregated from the application surface throughout the multiple treatments. The method comprises using a dispenser having a body portion and a dispensing portion. The body portion has a cavity to contain about 0.5 ml to about 20 ml of a tooth whitening composition. At one end there is at least one aperture for the dispensing of the tooth whitening composition to an applicator. The aperture, (and collectively when there is a plurality of apertures) has a cross-sectional of area less than about 10 sq. mm, preferably less than about 5 sq. mm, and most preferably less than about 2 sq. mm. Further a channel from the body portion to the applicator surface has a length of more than about 5 mm, preferably more than about 10 mm, and most preferably more than about 15 mm. At the other end of the body portion of the dispenser is a piston to dispense the tooth whitening composition through the channel to the applicator surface. This is manually operated by a twisting motion or by a push button. 
     The apertures in a preferred embodiment have an associated application surface to apply the anhydrous tooth whitening composition to ones teeth. This can consist of bristles, a pad, a sponge-like surface or fibrillated surface. The size of the apertures and the length of the channel will preclude the migration of catalase and moisture into the body of the dispenser during each dispensing and subsequent to the dispensing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational view of a dispenser for a tooth whitening composition. 
         FIG. 2  is an elevational view of the dispenser of  FIG. 1  in a vertical section. 
         FIG. 3  is an exploded view of the applicator tip of the dispenser. 
         FIG. 4  is an elevational view in a vertical section of the applicator tip assembled. 
         FIG. 5  is an elevational view of the drive mechanism of the dispenser. 
         FIG. 6  is an exploded view of the dispenser casing. 
         FIG. 7  is an elevational view of an applicator tip with a fibrillated surface in a casing in vertical section. 
         FIG. 8  is an exploded view of the applicator tip of  FIG. 7   
         FIG. 9  is an elevational view of an applicator tip with a sponge-like surface in a casing in a vertical section. 
         FIG. 10  is an elevational view of the applicator tip with a sponge-like surface of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     The invention will be disclosed with regard to the preferred embodiments with reference to the drawings. This invention is directed to a method of applying a tooth whitening composition to a persons teeth from a dispenser. 
     It has been found that peroxide containing tooth whitening compositions are very useful in tooth whitening. These usually are applied in multiple applications. The composition in the dispenser must be maintained substantially segregated from the applicator surface from the first application through to the last application. Consequently a technique for applying the composition is needed to fulfill these requirements. There also is a further requirement that it be easy for the individual to apply it themselves. This is provided by the techniques and dispensers of this invention. 
     The following are useful non-aqueous whitening compositions that can be used with the present dispenser. 
     
       
         
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Component 
                 Content 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Non-Aqueous Hydrophilic Polymer 
                 5 to 85 
                 wt % 
               
               
                   
                 Adhesive Enhancing Agent Peroxide 
                 0.1 to 25 
                 wt % 
               
               
                   
                 Peroxide Whitening Agent 
                 0.25 to 50 
                 wt % 
               
               
                   
                 Surfactant 
                 0 to 50 
                 wt % 
               
               
                   
                 Flavor 
                 0.1 to 2 
                 wt % 
               
               
                   
                 Peroxide Activator 
                 0 to 10 
                 wt % 
               
               
                   
               
             
          
         
       
     
     The nonaqueous hydrophilic polymers useful in the practice of the present invention preferably provide a viscosity for the composition in the range between about 1,000 cps to 900,000 cps. This will have a moisture content of less than about 2% and preferably less than about 1%. 
     A preferred nonaqueous liquid hydrophilic polymer vehicles suitable for use in the practice of the present invention includes polyethylene glycols, that is, nonionic polymers of ethylene oxide having the general formula:
 
HOCH 2 (CH 2 OCH 2 ) n OH
 
     wherein n represents the average number of oxyethylene groups. Polyethylene glycols available from Dow Chemical are designated by a number such as 200, 300, 400, 600, 2000 which represents the approximate average molecular weight of the polymer. Polyethylene glycols 200, 300, 400 and 600 are clear viscous liquids at room temperature, and are preferred for use in the practice of the present invention. 
     A second preferred nonaqueous liquid hydrophilic polymer used to prepare the composition of the present invention is comprised of a water soluble, nonionic block copolymer of ethylene oxide and propylene oxide of the formula:
 
HO(C 2 H 4 O) a (C 3 H 6 O) b (C 2 H 4 O) c H
 
     The block copolymer is preferably chosen (with respect to a, b and c) such that the ethylene oxide constituent comprises from about 65 to about 75% by weight, of said copolymer molecule and the copolymer has an average molecular weight of from about 2,000 to about 15,000, with the copolymer being present in the liquid tooth whitening composition in such concentration that the composition is liquid at room temperatures (23° C.). 
     A particularly desirable block copolymer for use in the practice of the present invention is available commercially from BASF and designated Pluraflo L1220 which has an average molecular weight of about 9,800. The hydrophilic poly(ethylene oxide) block averages about 65% by weight of the polymer. 
     Adhesion enhancing agents are used in the compositions of the present invention to enhance the adhesive properties of the anhydrous hydrophilic polymers and include inorganic materials as well as organic natural and synthetic polymers. Inorganic materials include amorphous silica compounds which function as thickening agents include colloidal silica compounds available under trademarks such as Cab-o-sil fumed silica manufactured by Cabot Corporation and distributed by Lenape Chemical, Bound Brook, NJ; Zeodent 165 from J.M. Huber Chemicals Division, Havre de Grace, Md. 21078; and Sylox 15 also known as Sylodent 15, available from Davison Chemical Division of W.R. Grace Corporation, Baltimore, Md. 21203. 
     Organic polymers useful as adhesion enhancing agents useful in the practice of the present invention include hydrophilic polymers such as carbomers such as carboxymethylene polymers such as acrylic acid polymers, and acrylic acid copolymers. Carboxypolymethylene is a slightly acidic vinyl polymer with active carboxyl groups. A carboxypolymethylene preferred for use in the practice of the present invention is a copolymer of acrylic acid cross linked with approximately 0.75% to approximately 1.5% polyallyl sucrose that is sold under the trade designation Carbopol 934, 974 by B.F. Goodrich. 
     Hydrophobic organic materials are also useful as adhesion enhancing agents in the practice of the present invention include hydrophobic materials such as waxes such as bees wax, mineral oil, plastigel, (a blend of mineral oil and polyethylene), petrolatum, white petrolatum, versagel (blend of liquid paraffin, butene/ethylene/styrene hydrogenated copolymer) acrylate and vinyl acetate polymers and copolymers, polyethylene waxes, silicone polymers such as dimethicone, silicone elastomers, organosiloxane resins, silicone gums and polyvinyl pyrrolidone/vinyl acetate copolymers. 
     Anhydrous whitening agents useful in the practice of the present invention include anhydrous peroxide containing compounds such as urea peroxide, sodium percarbonate, sodium perborate and PVP-H 2 0 2  complexes (hereinafter “PVP-H 2 0 2 ”). PVP-H 2 0 2  both linear and cross linked complexes are known to the art and are disclosed in U.S. Pat. No. 3,376,110 and U.S. Pat. No. 3,480,557 and have been used in compositions for treating acne vulgaris (U.S. Pat. No. 5,122,370). PVP-H 2 0 2  complexes are disclosed in U.S. Pat. No. 5,122,370. PVP-H 2 0 2  is stable in an anhydrous environment. By exposure to aqueous environments, as in the oral cavity, the whitening agent dissociates into individual species (PVP polymer and H 2 0 2 ). The PVP-H 2 0 2  complex is generally comprised of about 80% by weight polyvinyl pyrrolidone and 20% by weight H 2 0 2 . 
     Nonionic surfactants which are compatible with peroxide compounds serve as a solubilizing, dispersing, emulsifing and wetting agents and are especially effective to solubilize a flavor if included in the liquid whitening composition. A particularly useful nonionic surfactant is a water soluble polyoxyethylene monoester of sorbitol with a C10 to C18 fatty acid, marketed commercial under the Tween trademark. The Tween surfactants are mixtures of C10 to C18 fatty acid esters of sorbitol (and sorbitol anhydrides), consisting predominately of the monoester, condensed with about 10-30, preferably about 20, moles of ethyleneoxide. The fatty acid (aliphatic hydrocarbonyl monocarboxylic acid) may be saturated or unsaturated, e.g., lauric, palmitic, stearic, oleic acids. Polysorbate 20 (e.g., Tween 20) is especially preferred and is commonly referred to as polyoxyethylene (20) sorbitan monolaurate. The nonionic surfactant constitutes about 0 to 50% by weight and preferably 0.5 to 40% by weight of the liquid composition. 
     Flavoring agents that are useful include essential oils as well as various flavoring aldehydes, esters, alcohols, and similar materials. Examples of the essential oils include oils of spearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus, marjoram, cinnamon, lemon, lime, grapefruit, and orange. Also useful are such chemicals as menthol, carvone, and anethole. Of these, the most commonly employed are the oils of peppermint, spearmint and wintergreen. The flavoring agent is incorporated in the whitening liquid composition of the present invention at a concentration of about 0.1 to about 2% by weight and preferably about 0.1 to about 0.5% by weight. A sweetening material may also be employed as a complement to the flavoring material. Suitable sweetening agents are water soluble and include sodium saccharin, sodium cyclamate, xylitol, perillartien, D-tryptophan, aspartame, dihydrochalcones and the like. 
     Peroxide decomposition activators such as sodium bicarbonate, sodium carbonate, manganese gluconate may be incorporated in the liquid whitening gel composition of the present invention. The activator is relatively nonactive with the peroxide whitening agent when present in the stored nonaqueous liquid composition due to the anhydrous compositions. The activator functions to react with the peroxide to release oxygen when the liquid whitening composition applied to the teeth is contacted with saliva in the oral cavity. 
     An enhancement of the above compositions is to add a silicone adhesive agents. This will aid in holding the peroxide whitening agent onto tooth surfaces. This is formed by condensing a silicone resin and an organosiloxane such as polydiorgano siloxane. Useful silicone adhesive agents are available from the Dow Corning Company under the brand name BIO-SPA. These can be present in a content of about 1 to 80 wt present. 
     Suitable aqueous whitening composition are set out in Table 2. However other aqueous whitening compositions can be used. 
     
       
         
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
             
             
               
                   
                 Carbopol Polymer 
                 0.1 to 4 
                 wt % 
               
               
                   
                 Polyethylene glycol 
                 2 to 30 
                 wt % 
               
               
                   
                 Antioxidant 
                 .01 to .1 
                 wt % 
               
               
                   
                 Humectant 
                 0 to 50 
                 wt % 
               
               
                   
                 Thickener 
                 0 to 5 
                 wt % 
               
               
                   
                 Hydrogen peroxide 
                 1 to 35 
                 wt % 
               
               
                   
                 Monobasic sodium phosphate 
                 0 to 5 
                 wt % 
               
               
                   
                 Phosphoric Acid 
                 0 to 1 
                 wt % 
               
               
                   
                 Flavor 
                 .1 to 1 
                 wt % 
               
               
                   
                 Saccharin 
                 .01 to 1 
                 wt % 
               
               
                   
                 Purified water 
                 to 100 
                 wt % 
               
               
                   
               
             
          
         
       
     
     The Carbopol polymer, polyethylene glycol, flavors and saccharin been described above with regard to the non-aqueous tooth whitening compositions. 
     A preferred useful antioxidant is butylated hydroxyl toluene. Other useful antioxidants include nordihydroguararetic acid, propyl gallate and trihydroxy butrophenone. 
     A preferred humectant is glycerin. Other useful humectants include sorbitol and polytheylene glycol in a molecular weight range of 200 to 1000. Mixtures of humectants also can be used. 
     A preferred thickner is xanthan gum. However a range of organic natural and synthetic thickness can be used. These include carrageenan, starch, polyvinylpyrrolidone, and cellulose compounds such as hydroxypropyl menthyl cellulose, hydroxyethyl cellulose, hydroxyethylpropyl cellulose and hydroxybutyl methyl cellulose. 
     Hydrogen peroxide is a preferred whitening agent and preferably is added as a 35% solution of hydrogen peroxide in the peralkalai form. However it can be used at other concentrations and can be used in a form where hydrogen peroxide is released during use. Some such peroxides in another form are discussed above. 
     Phosphoric acid is the preferred acid added to adjust the pH of the composition. However a range of equivalent organic and inorganic acids can be used. These include sulfuric, hydrochloric, alginic, citric, succinic, lactic and tartaric acids and their salts. Included are salts of these acids with a preferred phosphoric acid salt being monobasic sodium phosphate. 
     The compositions can be made by mixing the components together in essentially any order. However one technique is for the components other than the polymers and thickeners, and water for the aqueous compositions, be admixed together and then the polymers and thickeners added. Water would be added to the aqueous to achieve the desired viscosity. An objective is for the production of a uniform whitening composition. 
     The dispenser  10  is shown as a complete unit in  FIGS. 1 and 2 . The dispenser is comprised of three sections. These are an applicator section  12 , a whitening product storage section  14  and a dispenser drive section  16 . The applicator section is comprised of an overcap  18 , an applicator surface  30 , an applicator surface holder  32 , an applicator mounting unit  36  and a delivery channel  34 . The whitening product in product chamber  40  is delivered to the applicator surface through delivery channel  34 . A tubular wall  20  forms the product chamber  40 . Piston  42  forms the upper wall of product chamber  40 . 
     The dispenser drive section  16  is comprised of the mechanism to advance piston  42  downward in whitening product chamber  40 . This dispenser drive section is shown in more detail in  FIG. 5 . Rotating unit  22  will rotate while tubular wall  20  of the whitening product chamber is stationary. 
       FIGS. 3 and 4  show the applicator section  12  in more detail. The applicator surface  30  is shown here as a bundle of bristles in holder  32 . The bristles are inserted into bristle holder  32  with flange  31  of the bristles held in recess  33 . The delivery channel  34  is held by friction in the center passage  35  of the applicator mounting unit  36 . Whitening product will flow through passage  37  of the applicator mounting unit  36 , into delivery channel  34  and then onto the applicator surface  30 . The applicator section  12  is shown prior to assembly in  FIG. 4 . 
       FIG. 5  shows the mechanism of drive section  16 . At a lower end is piston  42  which is attached to piston rod  50 . This piston rod  50  has threads  52  over a substantial part of its length. Stationary unit  58  is held in place in whitening product section  20  by an interlocking of ribs  56  and recesses  21  on product chamber wall  20  in  FIG. 2 . Rotary unit  57  fits into stationary unit  58  and has rotation limiting cams  55  and on a lower surface. These cams  55  interact with a cooperating cam surface in stationary unit  58  to limit rotation of piston rod  50  to only one direction to only move piston  42  downward. The piston cannot be retracted upward since this would draw product in delivery channel  34  towards and/or into the product chamber  40 . This could cause contamination of product in product chamber  40 . The piston is held in recess  51  of the piston rod  50 . A spring  54  causes rotating unit  57  to stay mounted within stationary unit  58 . 
       FIG. 6  shows the exterior parts of the dispenser in a exploded view. Shaft  23  of rotating unit  22  fits into and rotates within whitening product section  14 . It is held in place on the lower end of the product section tubular wall  20  by projection  13  and recess  17 . Overcap  18  fits onto end section  25  of the composition containing unit  40 . 
       FIG. 7  shows an applicator tip with a fibrillated surface The applicator tip is comprised of channel  60  having a cross-section  65  which receives the peroxide containing tooth whitening composition from storage chamber  40 . Fibrillated surface  62  is the application surface to apply the composition to the teeth. The peroxide tooth whitening composition flows through opening  64  of the channel  60 . Applicator surface holder  66  holds channel  60  and is in turn held in place by applicator mounting unit  68 .  FIG. 8  is an exploded view of the applicator tip of  FIG. 7 . Additionally shown in this view is a chamber  70  on the applicator surface holder channel  72  of the applicator mounting unit  68 . Flange  74  holds the applicator surface holder  66  in applicator mounting unit  68 . 
       FIGS. 9 and 10  show a sponge-like applicator surface. Delivery channel  76  has a porous sponge-like surface  78  on the applicator end. This applicator end has an aperture  80  for the delivery of the peroxide containing tooth whitening composition. An overcap  18  covers the applicator tip end. Shown are applicator tip holder  84  and applicator mounting unit  88 . The parts of this applicator tip are shown in more detail in  FIGS. 10 to 13 . 
     The chamber  40  will contain about 0.5 ml to about 20 ml of the tooth whitening composition. The delivery channels  34 ,  60 ,  76  will maintain the product in chamber  40  segregated from the applicator surface  30 ,  64 ,  78 . This segregation primarily is affected by the length and internal diameter of delivery channel  34 . This delivery channel should have a length of more than about 5 mm, and preferably more than about 10 mm, and most preferably more than about 15 mm. The internal diameter should be less than of about 4 mm and preferably less than about 2 mm. When there are a plurality of channels the additive diameter of all channels should be less than about 4 mm and preferably less than about 2 mm. The cross-sectional area of the channel should be less than 15 sq. mm, and preferably less than about 7 sq. mm. This is the cross-sectional area of a single channel or if more than one channel, cross-sectional diameter of the total number of channels. 
     The dispenser can be made out of any moldable plastics. Moldable thermoplastics are preferred. Suitable plastics include polymers and copolymers of ethylene, propylene, butadiene, vinyl compounds and polyesters such as polyethylene terephthalate. However the chosen plastics must be compatible with peroxide containing compositions and should no degrade such compositions. The bristles can be of any common bristle material such as nylon. The sponge-like materials can be of any common foam material such as urethane foams. The fibrillated surfaces will be comprised various thermoplastics. These are all known materials. 
     The applicator for the whitening composition can be any surface that can apply a viscous substance onto the hard surface of teeth. This can include a bristle surface, a sponge surface or a fibrillated surface. In the use of a bristle surface the delivery channel will deliver the composition to near the ends of the bristles. Usually there will be a single delivery channel. For sponge and fibrillated surfaces there usually will be plurality of smaller diameter channels so as to more uniformly distribute the composition onto a persons teeth. A fibrillated surface is an essentially planar surface that has a plurality of protruding fibrils up to about 3 millimeter in length. Such a fibrillated surface provides a mini-brush surface. 
     The viscosity is measured using a Brookfield Model DV II viscometer with spindle E. The sample is centered about 0.6 cm to 1.25 cm below the spindle tip. The viscometer motor is started which starts spindle rotation. The helipath switch on lowers the spindle. When the spindle penetrates the sample the pen on a recorder senses the different force on the spindle. The spindle is monitored for 1.5 minutes. The viscosity is calculated from a line tangent to the Y-slope and another averaging the X-slope an the intersection of these tangent lines.