Drug – bio-affecting and body treating compositions – Dentifrices – Oxygen or chlorine releasing compound containing
Reexamination Certificate
2000-11-17
2002-07-16
Rose, Shep K. (Department: 1624)
Drug, bio-affecting and body treating compositions
Dentifrices
Oxygen or chlorine releasing compound containing
C424S049000, C424S052000
Reexamination Certificate
active
06419905
ABSTRACT:
SUMMARY
The composition comprises carbamide peroxide (0.3-60%), xylitol (0.5-50%), a potassium salt (0.001-10%) and a fluorine salt (0.15-3%). A gel is disclosed that contains, as well as the bleaching composition, between 0.5 and 6% by weight of an appropriate gelling agent. The gel is suitable for bleaching dental pieces by means of a treatment that comprises applying an effective quantity of said bleaching gel to the dental pieces to be bleached. The composition can also be presented in the form of a toothpaste, colutory or elixir.
1. Field of the Invention
This invention relates to a composition suitable for bleaching the teeth, based on carbamide peroxide as well as presentation formulations thereof
2. Background of the Invention
Dental discoloration, or loss of whiteness of dental pieces with subsequent appearance of stains thereon, is a complex process in which numerous and different causes may be implicated. Types of dental discoloration can be classified in accordance with the localisation and aetiology of the stains. Recent studies propose the classification of dental stains (extrinsic and intrinsic) according to the chemistry of the dental discoloration [Nathoo, S. A., “The chemistry and mechanism of extrinsic and intrinsic discoloration”, JADA, 1997, 128:65-95]. According to this work, extrinsic dental stains, that is to say, those that are found on the surface of the dental pieces, are classified into the following groups:
(a) direct dental stains, that may be: (i) of N1 type, when the chromogen which binds to the dental surface to provoke the discoloration has a colour similar to that of the dental stain and may be due to the formation of a film of saliva that leads to fixing of components from the saliva by the dental enamel, to the ingestion of certain drinks and foods such as tea, coffee and wine, to bacterial adhesion and to the presence of metals in the oral cavity, or (ii) of type N2, when the chromogen changes colour after binding to the dental piece, due, for example, to the accumulation or chemical modification of proteins present in the film of saliva by means, for example, of denaturing with acids or detergents or else due to darkening, with the passage of time, of the dental stains of type N1 caused by drinks and foods; and
(b) indirect dental stains, in which a transparent material (or pre-chromogen material) binds to the dental piece and undergoes chemical reaction that produces the stain Among the products that provoke this type of stain there can be found, for example, food products rich in carbohydrates and sugars as well as certain therapeutic agents, for example, tin fluoride.
The intrinsic discoloration of the dental pieces is due to the presence of chromogenic material within the enamel or dentin. This type of discoloration can be due, among other things, to a fluorosis provoked by an excessive ingestion of fluorine during dental development, to the administration of tetracycline during the years of tooth formation, to a congenital malformation of the dental tissue, to certain hematologic disorders (erythroblastosis fetalis, thalassemia), to cracks and breaks in the dental pieces, to haemorrhages in the dental pulp, and to the normal ageing process.
Different methods and systems are known for eliminating dental discoloration and for provoking the bleaching of the dental pieces that comprise the use either of abrasives, such as prophylactic pastes, or a combination of abrasives and surfactants, for example, whitening toothpastes. ES-B-2079325 discloses a bleaching toothpaste containing an abrasive system (silica) and a detergent (sodium laurylsarcosinate). The use of abrasives for whitening dental pieces is not recommendable as it may lead to the elimination of part of the dental enamel along with the stains themselves which would facilitate the appearance of tooth decay and erosions due too the elimination of the natural defensive structure of the enamel with the subsequent dental hyperesthesia.
A tooth whitening composition in the form of a gel is provided by U.S. Pat. No. 5,718,886, wherein it is disclosed a stabilized anhydrous tooth whitening gel composition comprising carbamide peroxide dispersed in an anhydrous gelatinous carrier, said carrier comprising a polyol, a thickener, and xanthan gum in order to stabilize the gel composition against viscosity degradation during oral use.
In general, said whitening methods avoid the accumulation, and, to a certain extent, eliminate extrinsic dental stains although total and satisfactory elimination of the dental stains depends on the type of discoloration. In general, the extrinsic stains of type N1 can be avoided or eliminated by means of good oral hygiene, while the extrinsic stains of type N2, which are more difficult to eliminate, require the skill of a professional for dental bleaching. This is also true for stains of type N3. On the other hand, the elimination of intrinsic dental stains requires the use of products that penetrate the enamel and dentin with the aim of discolouring and dissolving the chromogens responsible for these stains.
Dental discoloration occurs widely in society (it is estimated that two out of every three adults suffers from some type of dental discoloration). It produces a certain anti-aesthetic effect that can even inhibit the smile of people suffering from discoloration. The occurrence can become particularly important in certain situations and professions where showing clean and white teeth is essential.
There exists, therefore, the need to have a new medium suitable for eliminating dental stains and bleaching the dental pieces that overcomes the drawbacks mentioned hereinabove. This objective may be attained by means of the use of a bleaching composition provided by this invention whose use leads to a clearing up of the dental enamel, which thus starts to a acquire a whiter and more brilliant appearance.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides a dental bleaching composition, hereinafter, composition of the invention, that comprises:
Components
% by weight with respect to total
Carbamide peroxide
0.3-60
Xylitol
0.5-50
Potassium salt
0.001-10
Fluoride salt
0.15-3
The carbamide peroxide is a mixture of hydrogen peroxide and carbamide whose amino groups neutralise the acidity of the hydrogen peroxide. This compound acts as an oxidative bleaching agent that liberates oxygen. It is able to oxidatively degrade numerous organic colouring agents present both in food products and in pharmaceutical products that produce dental colourings. In general, the organic colouring agents owe their dyeing capacity to the present of chromophor groups, that is to say, chemical groups rich in electrons, generally conjugated double bonds. Illustrative examples of organic colorants are, erythrosine, used as a developer for bacterial plaque, tartracine, used as a food additive, indigotine, used in the formulation of some drugs, and tetracycline, an antibiotic that produces dental colourings that range from yellow to brown. It is believed that oxidative degradation (oxidative bleaching) of this type of colorant occurs via a mechanism that implicates the decomposition of hydrogen peroxide and the formation of free radicals (HO—) that attack the double bonds present in the molecules of said colorants and, subsequently, produce the breakage of the double bonds and the oxidation of the carbons implicated to corresponding carbonyl groups. The carbonyl groups formed, although they also possess &pgr; (Pi) electrons as in the C═C double bonds, absorb in the ultraviolet zone of the spectrum and so do not contribute to discoloration. Numerous studies show that the bleaching activity of the carbamide peroxide (see for example, Van B. Haywood, “History, safety and effectiveness of current bleaching techniques and applications of the nightguard vital bleaching technique”, Quintessence Int. 23: 471-488 (1992); Howard E. Strassaler et al., “Carbamide Peroxide At-Home Bleaching Agents”, The New York State Dental Journal, April 1992, 30-34; Van. B. Haywood,
Biocosmetics, S.L.
Katten Muchin Zavis & Rosenman
Rose Shep K.
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