Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2001-08-02
2004-06-08
Krass, Frederick (Department: 1614)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S044000, C424S049000, C424S052000, C424S053000, C424S057000, C424SDIG006, C054S050000
Reexamination Certificate
active
06746679
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to compositions for whitening human teeth, and more particularly, to composition that do not contain hydrocarbon humectants and which when applied onto the surface of teeth acts to whiten without damage to tooth surfaces.
2. The Prior Art
A tooth is comprised of an inner dentin layer and an outer hard enamel layer, which is coated with a protective layer called the pellicle. Teeth can become stained when the chromogenic materials penetrate the enamel or chromogenic materials get trapped within the pellicle.
Many substances can stain or reduce the whiteness of one's teeth. In particular, the foods, tobacco products and fluids such as tea and coffee that one consumes tend to stain one's teeth. These products or substances tend to accumulate within the pellicle and then permeate the enamel. This problem occurs gradually over many years, but imparts a noticeable discoloration of the enamel of one's teeth.
Stain can be removed from tooth surfaces by the use of dentifrices, especially toothpaste, gels and powders containing active oxygen or hydrogen peroxide liberating ingredients such as peroxides, percarbonates and perborates of alkali and alkaline earth metals or complex compounds containing hydrogen peroxide with salts of the alkali or alkaline earth metals. However, these methods generally work very slowly and do not fulfill the needs of individuals who desire rapid whitening of teeth.
Individuals desiring rapid whitening of teeth can usually have it done in the dental office. One method for whitening teeth used by dental professionals involves the use of 30-35% hydrogen peroxide in combination with heat and/or light to promote the oxidation reaction. This method, although fast, is losing favor with dentists because clinical and scientific evidence shows that high concentrations of peroxide are deleterious to oral tissues. Improvements to this method have resulted in the usage of lower concentrations of hydrogen peroxide. However, this method also has a drawback because it is expensive and confines the patient to the dental chair for extended periods of time. Another professional method for bleaching teeth involves the use of hydrogen peroxide generating compounds such as urea peroxide (carbamide peroxide) at concentrations of 10-20% to achieve the desired whitening effect. Urea peroxide rapidly breaks down into hydrogen peroxide due to the water present in saliva. This method known as “at home use dentist dispensed bleaching system” involves the use of a mouth guard or tray within which the bleaching agent is placed. The tray is then placed upon the teeth of the patient and bleaching is allowed to take place. This method of treatment has drawbacks including tooth sensitivity, possibly due to demineralization and irritation of oral tissues. An additional disadvantage of the tray application method is that the bleaching effect is very slow compared to in-office methods.
One of the drawbacks to home use bleaching products containing oxygen liberating bleaching compounds is the tendency of these products to decompose within a relatively short period of time following manufacture with concomitant loss of all or a substantial amount of the available oxygen thereby limiting the efficacy of these products as teeth whitening compositions. Peroxy compounds such as hydrogen peroxide are notoriously unstable with respect to maintenance of peroxide level and have been found to be difficult to formulate into aqueous gels or pastes, which will have an adequate shelf-life and yet will readily liberate oxygen when applied to the oral cavity. Therefore, the prior art, for example U.S. Pat. Nos. 4,988,450 and 3,657,413 in formulating oxygen-liberating compositions for the whitening of teeth utilize anhydrous powders or water-free pastes or gels, which must be protected against contamination and chemical interaction. A drawback to the use of such anhydrous products is that, due to the absence of water, application of the oral composition tends to desiccate oral tissues, which leads to irritation and tissue damage.
In order to overcome the disadvantage of irritation and tissue desiccation, prior art discloses oxygen releasing toothpaste compositions, which have greater water content. However all have hydrocarbon humectants or hydrocarbon carriers such as glycerin, sorbitol, polyethylene glycol etc. The purpose of the humectant is to keep the composition from hardening upon exposure to air. Illustrative of oral compositions containing peroxide compounds include U.S. Pat. Nos. 4,980,152; 4,839,156; 4,522,805; 4,567,036; 4,405,599; 4,980,152; 5,171,564 and 5,256,402.
U.S. Pat. No. 4,980,152 discloses a non-abrasive aqueous oral gel composition comprising about 0.5 to about 10% by weight urea peroxide and 0.01 to 2% by weight of a fluoride-providing compound. The composition further includes a thickening agent such as carboxypolymethylene, a non-ionic surfactant such as PLURONIC F127 which is a trademark of the BASF Corporation, alkali soluble cellulose ethers as viscosity increasing agents, potassium phosphate as a buffering agent and glycerin as a carrier and flavoring and sweetening agents.
U.S. Pat. No. 1,839,156 discloses an aqueous denial gel containing 18-25% by weight of a polyoxyethylene polypropylene block copolymer gelling agent, hydrogen peroxide, 15-40% by weight of a polyethylene glycol humectant, flavor, sweetening agent and a non-ionic surfactant as the essential ingredients. This has been defined as a ringing gel. However addition of metal chelating agents have been described to have an adverse impact upon the stability of peroxide.
U.S. Pat. Nos. 4,522,805 and 4,567,036 disclose a stable toothpaste to aid in controlling periodontal disease, containing an oxidizing agent such as urea peroxide which dissociates into urea and hydrogen peroxide in the oral cavity, in a paste carrier comprising an anionic detergent, sorbitol and glycerin humectant and a thickening agent such as gum tragacanth, sodium alginate or sodium carboxymethyl cellulose.
U.S. Pat. No. 4,405,599 discloses toothpaste consisting essentially of a combination of calcium peroxide and sodium perborate oxidizing agents, dicalcium phosphate, calcium carbonate and magnesium carbonate cleaning agents, sorbitol humectant, cornstarch, cellulose gun thickening agents, and an anionic detergent. There is no indication of the effect of the toothpaste on whitening or stain removal from teeth. U.S. Pat. No. 4,980,152 discloses toothpaste consisting of urea or hydrogen peroxide with a fluoride compound as a pH stabilizing compound. There is no indication of the effect of the toothpaste on whitening or stain removal from teeth.
U.S. Pat. No. 5,171,564 discloses an oral care composition, which contains an abrasive in combination with a metal free peroxide, a chelating agent, a thickening agent such as a polyoxyethylene polypropylene block copolymer and humectants such as polyethylene glycol, glycerin or sorbitol.
U.S. Pat. No. 5,256,402 discloses an oral care composition, which contains an abrasive in combination with a metal free peroxide, a chelating agent, tooth desensitizing agents a thickening agent such as a polyoxyethylene polypropylene block copolymer and humectants such as polyethylene glycol, glycerin or sorbitol.
The prior art listed above, all contain hydrocarbon humectants and have a primary drawback of having limited stain removal/tooth whitening effectiveness. The purpose of the hydrocarbon humectants in tooth whitening compositions is to help solubilize flavor materials, surfactants and also to act as a carrier for peroxides. However, hydrocarbon humectants have a disadvantage because they are known to react with the active bleaching species such as free radicals and the perhydroxyl anions. Other prior art compositions contain abrasives, which have been shown to abrade enamel. In addition, newer tooth colored restorative materials contain very fine filler particles in order to increase polishability. Unfortunately, this
Krass Frederick
McGuire Woods LLP
Oral Health Clinical Services LLC
Ostrup Clinton
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