Drug – bio-affecting and body treating compositions – Dentifrices – Oxygen or chlorine releasing compound containing
Reexamination Certificate
1999-11-04
2002-06-25
Rose, Shep K. (Department: 1614)
Drug, bio-affecting and body treating compositions
Dentifrices
Oxygen or chlorine releasing compound containing
C424S049000, C433S215000, C433S217100
Reexamination Certificate
active
06409993
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates to dental bleaching compositions and methods for bleaching teeth surfaces. More particularly, the present invention is directed to sticky and viscous dental bleaching compositions which incorporate a perborate bleaching agent, such as sodium perborate monohydrate. Such compositions are advantageously used in combination with a dental tray.
2. The Relevant Technology
Since its introduction in early 1989, there has been significant interest among the dental profession and the general public for home-use tooth bleaching products and methods. In its simplest form, home bleaching products typically include a dental bleaching composition having a form of hydrogen peroxide as the active bleaching agent. Some compositions are in the form of toothpastes that are simply brushed onto the teeth during a person's daily dental hygiene routine. Other, more specialized bleaching compositions are adapted for extended contact with the teeth to be bleached, such as by means of a dental tray.
As a general rule whitening toothpastes have largely been ineffective in whitening teeth due to their relatively low potency or concentration of active bleaching agent coupled with the short duration of contact of such formulations with a person's teeth. Because of the manner in which toothpastes are manufactured, shipped, stored and sold, toothpastes are largely incapable of incorporating higher concentrations of active bleaching agents that remain stable over the intended manufacturing and storage life of the toothpaste prior to use. Moreover, it is well-known that people typically brush for 60 seconds or less, thus further reducing the effectiveness of the already low concentration bleaching agent within over-the-counter toothpastes.
In view of the foregoing, bleaching compositions having increased bleaching activity coupled with methods that maintain such dental compositions in contact with the teeth for longer periods of time are necessary to effect a noticeable bleaching effect in most people. Typical dental bleaching compositions include from 5-20% by weight of carbamide peroxide (CO(NH
2
)
2
.H
2
O
2
), which is a complex of urea and hydrogen peroxide.
Such dental bleaching compositions are typically applied to a person's teeth using a dental tray configured so as to retain the dental composition against the person's teeth. A self-sealing dental “splint” that can be used with more fluid and less sticky dental bleaching compositions are disclosed in U.S. Pat. No. Re. 34,196 to Munro. Munro recommends the use of Proxigel®, manufactured according to U.S. Pat. No. 3,657,413 to Rosenthal, which at the time contained only 0.6% carboxypolymethylene as a thickening agent, or a mixture of Proxigel® and Peroxyl® gel, which is an even more fluid bleaching composition than Proxigel®. The Munro dental tray is especially suitable for use with such highly fluid dental compositions since it is made from a rigid plastic material and configured so as to form a fluid-tight seal against the person's gums. Such trays, however, are not always comfortable for the user, particularly when the dental tray is held in place over long periods of time within a person's mouth.
Flexible, more comfortable-fitting dental trays that are preferably used in combination with more sticky and viscous dental bleaching compositions are disclosed in U.S. Pat. Nos. 5,098,303 and 5,234,342, both to Fischer. Such dental trays, while being more flexible and generally thinner-walled compared to prior dental trays, are preferably trimmed in a preferred embodiment so as to terminate below the gingival margin and then scalloped up and around the interdental papilla. This provides maximum bleaching of the entire surface of the person's teeth while minimizing or eliminating actual contact with the person's gums, including the interdental papilla, thus providing minimum discomfort. Further enhancement of bleaching is provides by optionally building “reservoirs” into the dental trays so as to allow for increased loading of bleaching composition within the dental tray that can contact the teeth.
In some countries hydrogen peroxide and certain derivatives thereof such as carbamide peroxide are not permitted as dental bleaching agents. However, liquid or highly fluid perborate compositions have been allowed. Whereas the substitution of a perborate bleaching agent for hydrogen peroxide or carbamide peroxide may be desirable, simply substituting perborates for carbamide peroxide or hydrogen peroxide in a sticky and viscous bleaching composition is not straightforward. Many, if not most, peroxide-based dental bleaching compositions, such as those disclosed in U.S. Pat. No. 3,657,413 to Rosenthal and U.S. Pat. Nos. 5,098,303 and 5,234,342 to Fischer, use carboxypolymethylene as the primary or preferred thickening and tackifying agent. Unfortunately, the combination of sodium perborate monohydrate with carboxypolymethylene was found to be unstable. Under the conditions under which the inventors mixed carboxypolymethylene and sodium perborate monohydrate, a vigorous reaction ensued.
From the foregoing, it will be appreciated that what is needed in the art are improved compositions and methods for manufacturing suitable dental bleaching compositions that include perborates, such as sodium perborate.
Additionally, it would be a significant advancement in the art to provide dental bleaching compositions having a perborate as the active dental agent which also had sufficient stickiness and viscosity so as to enable such compositions to adhere and retain a comfortable-fitting dental tray in place for the duration of a desired treatment regimen.
It would be another significant advancement in the art to provide perborate-based dental bleaching compositions having the aforementioned level of stickiness and viscosity which were sufficiently stable so as to maintain the desired bleaching activity until bleaching of the teeth is desired.
Such dental bleaching compositions and methods for their manufacture and use are disclosed and claimed herein.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention is directed to dental bleaching compositions used to treat tooth surfaces having a perborate bleaching agent. A preferred perborate bleaching agent is sodium perborate monohydrate, which has the formula NaBO
3
.H
2
O. The sodium perborate monohydrate is dispersed within a sticky carrier material, such as a mixture of an appropriate polyol and fumed silica. The sticky carrier material may include other gelling agents such as finely divided gel-forming metal oxides and/or organic thickeners known in the art and which are stable in the presence of sodium perborate monohydrate. Because the dental bleaching compositions according to the present invention are preferably sticky and viscous, they are especially suitable for use in combination with a custom dental tray that is designed so as to not exert significant mechanical pressure onto a person's teeth. The elimination or substantial reduction of mechanical pressures that are exerted onto a person's teeth during bleaching greatly increases the comfort experienced by the user. The inventive dental bleaching compositions are preferably formulated so as to a have a stickiness and viscosity that causes the bleaching compositions to adhere and retain a flexible, thin-walled dental tray against a person's teeth for as long as needed to carry out the desired bleaching process, such as the type of dental tray disclosed in U.S. Pat. Nos. 5,098,303 and 5,234,342, both to Fischer. For purposes of disclosing flexible, thin-walled, comfortable-fitting dental trays suitable for bleaching a person's teeth, the foregoing patents are incorporated herein by specific reference.
In order to carry out a desired bleaching process, the bleaching compositions of the present invention can be placed against a person's teeth for as little as 10 minutes and as long as 8 hours or more, depending on the po
Fischer Dan E.
Jensen Steven D.
Rose Shep K.
Ultradent Products Inc.
Workman & Nydegger & Seeley
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