Drug – bio-affecting and body treating compositions – Dentifrices
Reexamination Certificate
2003-01-15
2003-12-30
Rose, Shep K. (Department: 1614)
Drug, bio-affecting and body treating compositions
Dentifrices
C424S053000, C433S215000, C433S216000
Reexamination Certificate
active
06669930
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to tooth whitening liquid gels and more particularly to a stable, aqueous, peroxide-containing liquid gel whitening product useful for whitening tooth enamel.
2. The Prior Art
It has become desirable for a person's teeth to appear bright or “white”. Society places a high value on the “whiteness” of one's teeth. One whose teeth are white may enjoy more personal confidence and satisfaction and may even enjoy greater social acceptance.
A tooth is comprised of an inner dentin layer and an outer hard enamel layer that is the protective layer of the tooth. The enamel layer of a tooth is naturally an opaque white or slightly off-white (“ivory”) color. It is the enamel and dentin layers that can become stained or discolored. The enamel layer of a tooth is composed of hydroxyapatite mineral crystals that create a somewhat porous surface. These hydroxyapatite crystals form microscopic hexagonal rods or prisms that make up the enamel surface. As a result, the surface of the enamel layer presents microscopic spaces or pores between the prisms. It is believed that this porous nature of the enamel layer is what allows staining agents and discoloring substances to permeate the enamel and discolor the tooth. These remaining substances can occupy the microscopic spaces and eventually alter the color of the tooth.
Many substances that a person confronts or comes in contact with on a daily basis can “stain” or reduce the “whiteness” of one's teeth. In particular, the foods, tobacco products and fluids that one consumes tend to stain one's teeth. These products or substances tend to accumulate on the enamel layer of the tooth and form a pellicle film over the teeth. These staining and discoloring substances can then permeate the enamel layer. This problem occurs gradually over many years, but imparts a noticeable discoloration of the enamel of one's teeth. So long as the discolored teeth are still healthy and do not pose any health risk or problem, a product or substance that would whiten the discolored teeth would be advantageous.
It is also essential that a tooth whitening product that is to be used at home or in private by the consumer be safe and easy to use and be stable and retain its whitening efficacy during its storage on retail store shelves as well as over the period of use by the consumer.
Products and substances that are presently available to whiten teeth include a variety of different ingredients, but the primary active ingredient is a peroxide containing agent formulated into a liquid, solution, paste or gel. These products upon storage lose their whitening efficacy over time. A further limitation of commonly used aqueous peroxide solutions, is their brief period of efficacy when applied to the teeth in the oral cavity. For example, saliva, contains high concentrations of the enzyme catalase, which on contact, rapidly decomposes the peroxide into gaseous oxygen and water and so that there is only transitory contact of the peroxide whitening agent with the teeth. In addition, the low viscosities of aqueous peroxide solutions do not allow the peroxide whitening agent to remain in contact with the teeth for as long as is necessary to effect substantive whitening because of the constant flushing effects of salivary secretions. This tendency toward rapid decomposition of peroxide and the rapid flushing away of the peroxide agent applied to the teeth has severely limited their application to, and utility for, whitening teeth. It would be highly desirable, therefore, to provide a stable peroxide whitening liquid having increased retention on teeth to effect substantive whitening.
In copending U.S. patent application Ser. No. 10/155,496 filed May 24, 2002 there is disclosed a liquid gel dental whitening composition containing a peroxide whitening constituent dispersed in an aqueous liquid vehicle in which is dispersed a film forming component, the liquid gel rapidly drying when applied to the tooth surfaces to form in situ a gel-like film containing the peroxide whitening agent.
In one embodiment of the invention disclosed in U.S. Ser. No. 10/155,496 there is provided an aqueous tooth whitening liquid gel having enhanced stability and whitening efficacy, the liquid gel being comprised of an aqueous vehicle containing a film forming combination of an ethylene oxide linear homopolymer, a Carbomer and a peroxide whitening agent, the pH of the composition being maintained at an acidic level.
The whitening liquid gel of U.S. Ser. No. 10/155,496 is a portable oral care tooth whitener that can be conveniently painted onto the tooth surface. Upon the paint-on application to the teeth, the applied liquid whitening composition rapidly dries to produce, in situ, an adherent film of a thick gel that has the capacity to release the peroxide whitening agent over an extended period of time. The film adheres to the tooth surface whereby the released peroxide source then whitens the teeth to which the film is applied, the film being sufficiently adherent to counteract the tooth flushing action of saliva generated in the oral cavity. The adjustment and maintenance of the composition pH to acid levels provides a peroxide source that is stable to decomposition on storage.
A problem encountered in the use of the liquid whitening gel of U.S. Ser. No. 10/155,496 is that the composition is a clear, colorless product and the user when applying the product to tooth surfaces is uncertain, because of the product transparency, whether or not the tooth surfaces selected for whitening have had applied thereto the complete required application of the product. Less than complete application of the product to tooth surfaces can result in incomplete or reduced whitening results.
Attempts to opacify the clear product with opaque pigments particles encounter the problem that such opacifiers when present in the liquid whitening gel have been found to be interactive with, and decompose, the peroxide ingredient with the result that the whitening efficacy of the gel is reduced, providing undesirable uneven tooth whitening.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a stable, opaque liquid whitening gel which can be visualized by the user after application to tooth surfaces which gel comprises a peroxide containing whitening agent dispersed in an orally acceptable vehicle comprising a film forming ingredient and opacifying particles selected from polymer particles, titanium oxide and titanium dioxide coated mica particles, the peroxide containing whitening agent being substantially stable in the presence of the opacifying particles.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The vehicle used to prepare the liquid gel whitening composition of the present invention preferably includes a non-toxic volatile alcohol or any suitable mixture thereof. The presence of the volatile alcohol imparts a rapid drying property to the applied liquid gel whitening composition and is present in the composition at a concentration of about 10 to about 50% by weight and preferably about 25 to about 40% by weight. A monohydric alcohol such as ethanol is preferred as a volatile solvent. Water is included in the vehicle of the composition and about 5 to about 30% by weight of the composition and preferably about 10 to about 20% by weight.
The proportion of vehicle used to prepare the liquid gel composition of the present invention is generally within the range of about 40 to about 80% by weight of the invention and preferably about 40 to about 60% by weight of the composition. A humectant such as sorbitol, glycerin propylene glycol, PEG 600 is present in the vehicle of the present invention at a concentration of about 2 to about 15% by weight and preferably about 3 to about 8 by weight.
Examples of poly(ethylene oxides) useful in the practice of the present invention include PEG 2M, 5M, 7M, 14M, 23M, 45M and 90M commercially available from Union Carbide, Danbury, Conn., ranging in molecular weight from 1
Dixit Nagaraj
Hoic Diego A.
Mandadi Prakasarao
Patel Suryakant
Prencipe Michael
Bernard Lieberman
Colgate - Palmolive Company
Rose Shep K.
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