WO1997021417A1

WO1997021417A1 - Inclusion of tooth whitening oxidation chemistries into slow releasing food products

Info

Publication number: WO1997021417A1
Application number: PCT/US1996/019765
Authority: WO
Inventors: Paul Losee; F. Richard Austin; Blaine D. Austin
Original assignee: Cpi Incorporated
Priority date: 1995-12-12
Filing date: 1996-12-11
Publication date: 1997-06-19
Also published as: AU1415997A

Abstract

A composition for whitening teeth for placing in the mouth and method for manufacture, the composition comprising a water-free, non-hygroscopic base and carbamide peroxide.

Description

INCLUSION OF TOOTH WHITENING OXIDATION CHEMISTRIES INTO

SLOW RELEASING FOOD PRODUCTS

Field of The Invention

This invention relates to a preparation for introduction of whitening chemicals to

the surface of teeth and method of use and manufacture More particularly, the present

invention relates to such preparations in a solid or tablet form, which is less costly and

easier to use for the consumer than existing products available

Background of the Invention

The anatomy of a tooth is well known with an inner dentin layer and an outer hard surface enamel layer Enamel is an opaque white or off-white color It is the enamel that

can become stained and/or discolored The porous nature of the enamel layer allows stain

and discoloring substances to enter the enamel surface and thereby discolor the tooth

Many substances and food items, such as juices, tea, coffee and tobacco, can

"stain" or reduce the "whiteness" of teeth These substances are consumed on a daily

basis and gradually over several months or years can impart a noticeable discoloration of the enamel surfaces of the teeth

Presently the dental profession uses methods to whiten teeth that are based on the presentation of either hydrogen peroxide or carbamide peroxide in a gel preparation to the

enamel surfaces of the teeth These compounds come in varying strengths from 10 wt % to 35 wt % The gels are delivered either by the dentist in the dental office, accompanied

by light and/or heat, or by using home-use kits via plastic trays fitted to the teeth The home-use kits, which use low concentration compounds, require the

fabrication of a plastic tray filled with a whitening gel before placement over the teeth

For proper fitting, a dentist must usually fabricate the tray The treatment time is high and

the activities of the consumer are restricted while the tray is in place Generally several treatments are required The disadvantage of this system is the lengthy time required to

whiten teeth and the high inconvenience accompanying its use

Faster whitening is accomplished by the dentist in the office, where the higher concentration gels are used However, the cost to the consumer is higher and there is

additional risk of the higher concentrations causing some soft tissue irritation

There is a demand in the marketplace for a less costly and more easily utilized whitening product which is without the constraints on time, the mess of the gels and lack of dental trays

Candies, tablets, gums, and the like have been used as a vehicle for introducing

various chemical agents to a tooth surface A strict requirement, however, for these compositions is that they have a long shelf-life, at least on the order of several weeks This requirement has limited the use of solids for tooth-whitening preparations because,

in general, the active components for tooth-whitening are not stable under ambient

conditions of humidity and temperature In solid compositions, these components quickly

become degraded to unsuitably low concentrations In addition, the whitening

compositions frequently degrade to reactions products with a bad taste Thus, the

compositions can become unpalatable even before the active component has degraded to

insufficient levels An example of a tablet or gum or tooth treatment is disclosed in U S Patent

4,302,441 issued to Muhlemann et al on November 24, 1981 This patent discloses a solid oral preparation comprising active urea hydrogen peroxide (carbamide peroxide) that

is effective in countering acid fermentable carbohydrates in dental plaques The solid oral

composition in the form of a lozenge tablet or chewing gum comprises urea hydrogen

peroxide and, in the absence of glycerol, and a sweetener selected from the group

consisting of mannitol, sorbitol, xylitol and saccharin, and a carrier selected from the

group consisting of soluble cellulose ethers and carbohydrate gums These compositions

may be effective in introducing carbamide peroxide to the surface of the teeth of the

person to whom it is administered, but they suffer from having a short shelf life In solid

materials carbamide peroxide gradually reacts with ambient water such as from humidity

in the air and with water in the composition to form urea and oxygen or hydrogen

peroxide This not only leads to a decrease in the effective amount of the carbamide

peroxide, it also produces urea, which in small concentrations lends a sharp, unpleasant

taste to the composition Thus, even before the composition becomes ineffective from depletion of the carbamide peroxide it becomes unpalatable in only a few days and unacceptable as a consumer product

Objects of the Invention

It is, therefore, an object of the invention to provide a system for delivering

whitening agents to tooth surfaces that overcomes the shortcomings of the prior-art gel systems It is also an object of the invention to provide a whitening composition with a long

shelf-life that does not degrade quickly to become unpalatable or ineffective

An object of the invention is also to provide a system that is less costly and can be

used by the consumer in a manner that does not restrict activity and requires an undue

amount of time

It is further an object of the invention to provide a composition in a solid form that

is commercially acceptable, that is, introduces a sufficient carbamide peroxide to the tooth surface to provide a whitening effect, but also to provide sufficient stability that the

product over a storage period of several weeks will not decompose to form urea to give

the product an unpleasant taste.

It further an object of the invention to provide a system that avoids the messy gels and liquids, and high peroxide concentrations

Further objects will become evident in the description that follows

Summary Of The Invention The invention involves a composition and method for manufacture for a solid

orally administered formulation containing carbamide peroxide and a water-free base

formulation that is non-hygroscopic The formulation is stable, having a shelf life of

several weeks

The active ingredient in the present invention, carbamide peroxide, CON₂H₄,H₂O₂

is the addition compound of hydrogen peroxide and urea and is also known as urea

peroxide, or urea hydrogen peroxide The composition of the invention contains carbamide peroxide in a whitening effective amount, i e , an amount to be efficacious to effect a whitening of teeth when taken orally (placed in the mouth) and chewed or

dissolved to release the carbamide peroxide A efficacious amount has been found to be greater than about 3 wt % If the amount of carbamide peroxide is too high, greater than

about 12 wt %, it may impart an unpleasant taste to the composition Suitable amounts

for a commercially suitable product have been found to be between about 3.5 wt % and

about 10 wt %

As mentioned above, carbamide peroxide when reacted with water decomposes into urea In the compositions of the present invention, the carbamide peroxide is isolated

from water while in the product, thus the solid product does not degrade and has a long

shelf-life As the product is placed in the mouth and slowly dissolved by the saliva, it

reacts with the saliva to produce a bleaching effect on the tooth surface without producing

an unpleasant taste It has been found that any urea that is formed in this process of

dissolution in the mouth is insufficient to impart a bad taste to the product

It has been found that prior-art gum, tablet and gum compositions contain water, or often contain substances that attract water from the humidity in the air In normal

compositions this water is no problem, but if carbamide peroxide is present, that water is

available to react with and degrade the carbamide peroxide to produce urea

In the practice of the present invention, water is expelled from the composition of

the invention and because of the inherent properties of the base of the composition of the invention, there is no reabsorption or attraction of water from the humidity in the air

Accordingly, the carbamide peroxide is protected or shielded from water and the decomposition reaction does not take place sufficiently to produce an unpleasant taste

Accordingly, it has been found that the compositions of the present invention can be stored for several weeks with no detectible deterioration in taste and with an insignificant

loss of the active ingredient.

The base composition, for purposes of this disclosure, is the portion of the

composition of the invention other than the carbamide peroxide component. The base of the present invention is essentially water-free and non- hygroscopic. By "water-free" is

meant that it contains negligible water that is free to react with the carbamide peroxide

The composition may contain waters of hydration, but they must be bound sufficiently to

the base composition or present in such a small amount to provide negligible reactive water

By "non-hygroscopic"is meant a composition lacking a hygroscopic property, i.e.,

the tendency of the substance to hydrate by absorbing water, usually from the ambient

humidity The base material should be non-hygroscopic at ambient temperatures and humidities usually encountered during handling and storage The composition of the

invention may comprise materials that are hygroscopic, but they must be present in small enough amounts to retain the non-hygroscopic nature of the entire base composition Essentially the substantial portion of the base material should be non-hygroscopic. The

base is a solid, i.e., a solid or semisolid material such as a candy, gum, tablet, paste, or any

solid or semisolid form capable of being placed in the mouth and which is dissolvable to

release the carbamide peroxide to the surface of the tooth The substantial portion of the base comp ^.ition is preferably isomalt A derivative

of sucrose, isomalt is an equimolar mixture of two isomeric disaccharide polyols, α-D-

glucopyranosyl-l,6-D-sorbitol (GPS) and α-D-glucopyranosyl-l, l-D-mannitol (GPM)

Isomalt is sold under the trademark Palatinit™ by Palatinit Sussungsmittel GmbH, Mannheim, Germany Isomalt is non-hygroscopic, particularly at ambient temperatures

and humidities At 25 °C isomalt absorbs very little water At temperatures as high as

60 °C and 80 °C the relative humidity must be 75% and 65% respectively for significant

water absoφtion A detailed discussion of isomalt and its various properties is disclosed

in Isomalt, by Peter Strater and William E Irwin in Alternative Sweeteners, edited by Lyn

O'Brien Nabors and Robert C Gellardi, Marcel Dekker, Inc., 1992

Other suitable base materials include other non-hygroscopic materials, and may

include, but not be limited to disacharide materials, and sweetening compounds with a low molecular polarity

The base composition may comprise other suitable ingredients that are used in orally administered compositions, such as flavors, sweeteners, anti-oxidants, stabilizers,

colorants, and the like.

The composition of the invention is made by incoφorating the carbamide peroxide whitening compound into the solid base material by first heating the base material to a temperature sufficient to drive off any water in the composition For isomalt, this is a

temperature of about 150°C or above The base material is then cooled to a temperature

at which the carbamide peroxide can be incoφorated and mixed into the base material

As the temperature approaches near 120°C, the carbamide peroxide disassociates

Accordingly, the preferred mixing temperature is 1 18°C or below When isomalt cools to near 1 10°C it becomes difficult to mix the carbamide peroxide in an isomalt base

Accordingly the preferred temperature for mixing in isomalt is 1 14°C or above In

summary, for mixing carbamide peroxide in isomalt, the mixing temperature is preferably

between 1 14°C and 118^QC, more preferably about 1 16°C After incorporating the carbamide peroxide, the material is then allowed to

solidify The solid base can be formed into hard candy shapes by any suitable method, or

crushed into powder and then hard pressed in to tablets, or otherwise processed by

conventional methods into a solid form that can be orally administered Basically, any process that permits the heating to expel the water and the mixing temperature of the

carbamide peroxide is suitable for the present invention The other components of the

composition, i e., the sweeteners, stabilizers, flavors, etc are added at any suitable time,

as dictated by their properties

When the composition of the invention is placed within the mouth, the composition slowly dissolves adjacent to the teeth which provides an effective amount of

the carbamide peroxide to the surface of the tooth Preferably, a candy or tablet of the invention is composed to dissolve slowly over about a 20 minute period A consistent

daily use of the tablets of the invention will then obtain a maximum whitening of the teeth

of the consumer

Brief Description Of The Drawing

The sole figure is a flow diagram of a process of the invention

Detailed Description Of The Invention

Referring to the figure which is a flow sheet of the method of the invention, a non-

hygroscopic base is provided and heated to 150° C to drive of the water in the base The

base is cooled to 1 16°C, the temperature at which carbamide peroxide is added and

mixed The material is then allowed to cool to form a solid material Examples

Example I - Hard Candy Composition

Candy bases were made and formed into hard candies according to the invention

A base mixture comprising isomalt and the ingredients shown in Table A were compounded by conventional candy making technique and then heated to a temperature

of 150°C for a sufficient period to drive of any free water The mixture was then cooled

to 1 16°C and the active ingredient, carbamide peroxide, was added The other ingredients

were added and compounded according to standard candy making practice The

composition was then allowed to cool and was molded formed into candy shapes by

conventional techniques Alternately, the composition is allowed to solidify, ground, and the ground composition pressed into tablets The amounts of the ingredients in percent,

based upon the original unheated mixture and the final product are shown in Table A

TABLE A CANDY FORMULATION

Base Ingredients Mixture Final

(wt %) Composition

(wt %)

Isomalt 78 0 93 19

Titanium Dioxide 0.2 0 24

Aspartame 0 85 1.0

Deionized Water 16 30 -

Flavoring (Pina Cola) 0 65 0.78

Active Ingredient

Carbamide Peroxide 4 0 4 78 Example II

A candy composition was made, essentially as in Example I, except a different

flavor was used The amounts of the ingredients as a percentage of the initial mix are

shown in Table B

TABLE B

CANDY FORMULATION

Base Ingredient Mix (wt %)

Isomalt 78 0

Titanium Dioxide 0 2

Aspartame 0 85

Flavoring (Spearmint) 0 40

Water 16 55

Active Ingredient

Carbamide Peroxide 4 0

Example III

A hard candy composition was made essentially as in Example I except that

Vitamin E was added as an antioxidant and a preservative The amounts of the

ingredients as a percentage of the initial mix and the composition of the final product are

shown in Table C TABLE C

VITAMIN E CANDY FORMULATION

Base Ingredient Mιx (wt %) Final

Composition (wt %)

Isomalt 78 2 90 20

Titanium Dioxide 0 2 0 23

Aspartame 0 85 0 98

Water 13 30 -

Flavoring (Cherry) 0 65 0 75

Vitamin E 3 0 3 46

Active Ingredient

Carbamide Peroxide 3 8 4 38

Example IV

A composition was produced in the form of a tablet This accomplished by mixing

essentially water-free isomalt in a powder form with the other ingredients also in powder

form, and pressing the powder mixture into tablets by conventional techniques Isomalt

is available commercially in an essentially water-free condition Alternately, the isomalt may be heated to 150°C, resolidified and ground to form a power The base composition was mixed, heated to 150°C for sufficient time to drive off the free water The

composition of a tablet in grams and wt % of the ingredients are shown in Table D TABLE D

TABLET COMPOSITION

10% ACTIVE INGREDIENT

Base Ingredient Grams (wt %)

Isomalt 50 79 66

Citric Acid 0 2 0 32

Vanilla 3 5 5.58

NutraSweet 0 95 1 51

Magnesium Stearate 1 5 2.39

Peppermint Oil 0 32 0 51

Active Ingredient

Carbamide Peroxide 6 3 10 04

TOTAL 62 77 100 00

Example V

This example illustrates a paste composition of the invention A composition of the invention in a semisolid paste form is manufactured by blending, using conventional

tooth-paste technology ingredients, in the amounts listed in Table E The result is a tooth¬

paste composition that may be used for whitening teeth Other ingredients used in

conventional tooth-paste manufacture may also be used, as long as the composition is

compounded without the addition of the water that would react with the active ingredient TABLE E

TOOTHPASTE COMPOSITION

Base Ingredient Grams

Dicalcium Phosphate Dihydrate 27 7

Glycerin 17 8

Sorbitol 16 7

Hydrated Silica 2 2

Flavor (Peppermint/Wintergreen) 1 1

Cellulose Gum 2 8

Isomalt 1 1 1

Sodium Bicarbonate 1 1 1

Sodium Saccharin 1 1

Sodium Laurel Sulfate 2.8

Active Ingredient

Carbamide Peroxide 5.6

TOTAL 100 0

Comparative Examples

Compositions were made, essentially as described in Example I, except that hygroscopic base materials were substituted for the isomalt The final product was stored

in ambient room-temperature/humidity conditions and periodically tested for taste and

amount of active ingredient (AI) remaining in the composition

The hygroscopic base materials used were mannitol, sorbitol, and xylitol In compositions with these materials there was a noticeable urea taste after 2 days The amount of the carbamide peroxide active ingredient decreased from 4 wt.% to 2 wt.% in

6 days. Basically, for all the comparative compositions made from hygroscopic bases, the composition became uneflficacious and unpalatable in less than one week due to the decomposition of the carbamide peroxide.

As a comparison, composition made according to Examples I to IV above were

made and stored under similar conditions After one month there was no detectable

change in taste and no detectable decrease in the amount of carbamide peroxide.

As seen from the above data, the use of a non-hygroscopic base material is critical to the invention. The candy compositions with the comparative base materials all

exhibited poor shelf life. This was due to the hygroscopic nature of the base material that

rendered the carbamide peroxide unstable. In comparison, the composition of the

invention shows excellent shelf life with no urea taste nor significant deterioration of the

carbamide peroxide.

While this invention has been described with reference to certain specific embodiments and examples, it will be recognized by those skilled in the art that many variations are possible without departing from the scope and spirit of this invention, and

that the invention, as described by the claims, is intended to cover all changes and

modifications of the invention which do not depart from the spirit of the invention.

Claims

What is claimed is

1 A non-hygroscopic solid composition for a tooth whitening composition for placing in the mouth comprising

carbamide peroxide in an amount effective to dissolve and produce a whitening

effect on teeth when the composition is in the mouth,

a solid, essentially water-free, non-hygroscopic base

2 The composition of claim 1 wherein the carbamide peroxide is present in

an amount above 3 weight percent and below 12 weight percent, based upon the total

weight of the composition

3 The composition of claim 1 wherein the carbamide peroxide is present in

an amount between 3 5 weight percent and 10 weight percent, based upon the total weight of the composition

4 The solid composition of claim 1 wherein the base comprises a non-

hygroscopic polyol in an amount sufficient to maintain the base as essentially non- hygroscopic

5 The solid composition of claim 4 wherein the non-hygroscopic polyol is

an equi-molar mixture of two isomeric disaccharide polyols 6 The solid composition of claim 5 wherein the mixture is isomalt

7 The solid composition of claim 5 wherein the base comprises hygroscopic

materials in an amount sufficiently small to retain the non-hygroscopic nature of the entire

base composition

8 The solid composition of claim 1 wherein the solid, essentially water-free,

non-hygroscopic base is in the form of a tablet

9 The solid composition of claim 1 wherein the solid, essentially water-free,

non-hygroscopic base is in the form of a candy

10 The solid composition of claim 1 wherein the solid, essentially water-free,

non-hygroscopic base is in the form of a gum

1 1 The solid composition of claim 1 wherein the solid, essentially water-free,

non-hygroscopic base is in the form of a paste

12 A method for manufacturing a solid composition for whitening teeth

comprising, a providing an essentially non-hygroscopic base. b heating the base to a temperature sufficient to drive essentially all of the

free water from the base, c mixing a tooth whitening amount of carbamide peroxide into the base at

a temperature below the decomposition temperature of carbamide peroxide, and

d allowing the mixture to cool to form a solid

13 A method for manufacturing a solid tooth whitening composition comprising,

a heating isomalt to a temperature of 150°C sufficient to drive essentially all of the free water from the isomalt,

b allowing the isomalt to cool to a temperature between 1 14 ° C and 1 18 ° C,

c mixing into the base carbamide peroxide in an amount between 3 5 and 4 weight percent, based upon the total composition, at a temperature between about

1 14°C and 1 18°C, and d allowing the mixture to cool to form a solid

14 The method of claim 13 wherein the carbamide peroxide is mixed into the isomalt at a temperature of about 1 16°C

15 The method of claim 12 wherein the solid is formed into shapes

16 The method of claim 12 wherein the solid is ground and then pressed into tablets 17 The method of claim 12 wherein the solid is molded into shapes before the

isomalt completely solidifies

18 A method for manufacturing a solid tooth whitening composition comprising

compounding and compressing an essentially water-free powder that comprises

a non-hygroscopic base and a tooth-whitening amount of carbamide peroxide into tablets.

19 A method of whitening teeth comprising

placing in the mouth an essentially water-free composition comprising carbamide

peroxide in an amount effective to produce a whitening effect on teeth when the composition is placed in the mouth, and a solid, essentially water-free, non-hygroscopic

base

20 A tablet comprising of an essentially water-free, hygroscopic base and a tooth whitening amount of carbamide peroxide

21 A gum comprising of an essentially water-free, hygroscopic base and a

tooth whitening amount of carbamide peroxide

22 A candy comprising of an essentially water-free, hygroscopic base and a tooth whitening amount of carbamide peroxide

23 A paste comprising of an essentially water-free, hygroscopic base and a tooth whitening amount of carbamide peroxide

24 A method for stabilizing carbamide peroxide in a solid material adapted for placing in the mouth comprising

compounding the carbamide peroxide with an essentially water-free, non-

hygroscopic base to form the solid material