WO2010010196A1

WO2010010196A1 - Dental bleaching package

Info

Publication number: WO2010010196A1
Application number: PCT/EP2009/059620
Authority: WO
Inventors: Jacobus Alting
Original assignee: Jacobus Alting
Priority date: 2008-07-24
Filing date: 2009-07-24
Publication date: 2010-01-28
Also published as: NL1035744C2; NL1035744A1

Abstract

A kit comprising a dental applicator provided for insertion in the mouth, the applicator having a first (1) and a second (2) upright wall on opposite sides of a trough (5), the trough (5) containing a preset amount of bleaching agent for bleaching teeth and being provided for receiving and permitting immersion of the teeth of at least one dental arch in the bleaching agent, the kit further comprising a package for the dental applicator with an inner volume in which the dental applicator is received, characterised in that the package is sealed along at least one.closure edge, in that the package is made of a material comprising a film, which is impermeable to visible and UV light and comprises an oxygen barrier, and in that the inner volume of the package is maintained under reduced oxygen pressure.

Description

Dental bleaching package.

The present invention relates to a kit comprising a dental applicator provided for insertion in the mouth, the applicator having a first and a second upright wall on opposite sides of a trough, the through containing a preset amount of bleaching agent for bleaching teeth and being provided for receiving and permitting immersion of the teeth of at least one dental arch in the bleaching agent, the kit further comprising a package for the dental applicator with an inner volume in which the dental applicator is received, according to the preamble of the first claim.

Over the last years the importance of tooth whitening has received increasing attention. The technique has moved from a situation wherein the tooth whitening treatment is carried out in the dentist's office where tooth bleaching is achieved using irradiation with a laser source, to a situation where a wide variety of over-the-counter tooth whitening products and delivery systems are available, which permit the average consumer to whiten its teeth at home. Office bleaching methods usually employ either carbamide peroxide, which decomposes in the mouth to hydrogen peroxide, or hydrogen peroxide as bleaching agent. Bleaching gels typically contain 10- 30% carbamide peroxide or 3-10% hydrogen peroxide concentration. Carbamide peroxide is often preferred because of its better stability against decomposition. Care has to be taken that coating of the teeth with the bleaching composition and irradiation with the laser light are carried out in such a way that the peroxide is activated for bleaching, at minimum risk to overheating the pulp of the tooth. Usually one treatment will suffice to achieve substantial bleaching. Home bleaching methods focus on low- concentration whitening, which is far less effective and involves the use of a thin mouthguard or strip that holds a relatively low concentration of oxidizing agent next to the teeth. To improve the result, delivery systems which seek to improve the contact between the teeth and the whitening composition have been developed. Examples of delivery systems include strips coated with the tooth whitening composition, trays filled with tooth whitener, tooth whiteners incorporated into toothpaste, paint-on applicators, and others using brushes with bristles and foam-type brush applicators. Over-the-counter whiteners today fall into three major categories, in particular trays and gels, strips and paint-on whiteners. In tray and gel systems, a flexible tray is filled by the user with the whitening formulation and placed over the teeth. However, extrusion of the gel from the tray on to the gingival and the mucosa the ensuing risk to soft tissue irritation are difficult to avoid. When using strips which are placed on the teeth, a good portion of the strip tends to lay on the gingival area and to cause irritation.

Bleaching compositions are usually peroxide based and decompose readily when exposed to light or air, their activity has been found to deteriorate fast once the package containing them has been opened. To achieve good whitening, it is important that a sufficient amount of peroxide is present in and delivered by the composition; that the composition shows good adhesion to the teeth and is capable of penetrating the tooth enamel to a certain extent, that the composition has a suitable viscosity to permit application. US5989569 discloses a method for whithening teeth according to which an initially flat strip of material is applied to a portion of a tooth, to an entire tooth, or to a row of adjacent teeth. The side of the strip facing the tooth is capable of conforming to the teeth to be covered and is either coated with a tooth whitening substance or the teeth are coated with the substance and the strip is placed over the substance. The substance is preferably in a highly viscous state, such as a gel, such that it provides not only the active compound but also tackiness between the tooth surface and the strip to hold the strip in place. The strip is preferably of a size that individually fits the entire upper or lower rows of teeth when positioned against the teeth. The strip readily conforms to the teeth by lightly pressing it against the teeth. The strip is easily removed after use by peeling it off. Cadco Dental Products in Oxnard, Calif, have developed disposable U-shaped soft foam trays saturated with a premeasured quantity of bleaching agent.

US5575654 discloses a device for the treatment of dental arches and periodontal tissue. The device comprises a prefabricated dental appliance made of a non-porous polymeric material, which is adaptable to fit a range of variously sized dental arches. The device has a trough which contains a premeasured amount of bleaching agent, in which the teeth of a dental arch may be received for a whitening treatment. According to US 5575654, the dental device may be packaged in a kit in such a way that the pre-dispensed bleaching agent is sealed in a package surrounding the appliance, or sealed in the trough of the dental appliance. As a bleaching agent use is made of carbamide peroxide or another bleaching agent. Alternatively, the medicinal agent may be packaged in a separate container located adjacent to the trough, the container being sealed in a manner whereby the medicinal agent is capable of being directly expelled into the trough of the dental appliance when the seal is opened. One embodiment features a dental appliance wherein a first strip of open cell foam is affixed along the frontal inner wall of the dental appliance and a second strip of open cell foam is affixed along the rear inner wall of the dental appliance such that a reservoir cavity for containment of the medicinal agent is formed along the bottom of the trough of the dental appliance. The appliance further contains a buffer region in the area around the periodontal tissue surrounding the teeth subject to treatment, to prevent the periodontal tissue from coming into contact with the active bleaching agent.

US6669930 discloses to use an opaque liquid whitening gel which can be visualized after application to the tooth surface. The gel comprises a peroxide containing whitening agent, a film forming ingredient and opacifying particles. Suitable opcifying particles include polymer particles, for example polyethylene, polypropylene and ethylene/proylene copolymers, polytetrafluoro-ethylene and polyhexafluoropropene, or titanium oxide and titanium dioxide coated mica particles. The opacifying polymers have an average particle size of about 0.5 to about 100 microns. JP4257512 by DEMETORON RISAACHI CORP discloses a tooth bleaching paste containing concentrated hydrogen peroxide gel, a redox color indicator visually informing the operator of the activity of hydrogen peroxide in the paste, a viscosity modifier to cause the adhesion of the paste or gel resistant to sagging under gravitational force and provide a process for bleaching tooth with the gel or paste. Suitable examples of the viscosity modifier include non-aqueous inert silica gelling agent such as fumed silica. The gel or paste is applied to the surface of tooth to be bleached and the surface is irradiated with light energy having wavelength of 400-700nm to bleach the tooth.

When analysing the existing applicators for tooth whitening devices suitable for home bleaching, the inventors have observed that often use is made of carbamide peroxide because of its better stability upon storage. Up to now, despite of its better activity, hydrogen peroxide has known limited use in home bleaching applicators, mainly because it easily decomposes upon the slightest contact with air or light.

It is therefore the object of the present invention to provide a kit which permits stable storage of hydrogen peroxide bleaching compositions in a ready to use applicator suitable for home bleaching. This is achieved according to the present invention with a kit showing the technical features of the characterising portion of the first claim.

Thereto, the kit of the present invention is characterised in that in that the package is sealed along at least one closure edge, in that the package is made of a material comprising a film, which is impermeable to visible and UV light and comprises an oxygen barrier material, and in that the inner volume of the package is maintained under reduced oxygen pressure.

The oxygen pressure maintained in the inner volume of the package is preferably below 2 %, preferably below 1 %, more preferably below 0.6 %, most preferably below 0.5 %. Or in other words, in the inner volume of the package oxygen concentrations are reduced with respect to ambient conditions with at least 90 %, preferably at least 95 %, more preferably at least 97 %, taking into account that normal ambient conditions relate to an oxygen pressure of about 20 %.

Such oxygen poor conditions can be achieved by filling the package with an inert gas, for example nitrogen or any other gas considered suitable by the skilled person. But preferably the oxygen poor conditions are achieved by subjecting the inner volume of the package to vacuum, in particular by maintaining in the inner volume a pressure below 55 kPa, preferably below 40 kPa, more preferably below 5 kPa, most preferably below 1 kPa. Shielding the bleaching composition from oxygen and UV and visible light has the effect that hydrogen peroxide decomposition, which is facilitated upon contact with oxygen and or upon irradiation with visible and/or UV-light, is counteracted upon storage. This permits solving a problem which has existed for many years and which up to now prevented the use of hydrogen peroxide as a bleaching agent in home bleaching applications. Up to now carbamide peroxide was primarily used in home bleaching applications because of its better stability. With the present invention, the shelf life of hydrogen peroxide bleaching compositions can be prolonged to over 18 months, often to over 24 months. As a result, the more active hydrogen peroxide can now be made available for use in home tooth whitening products, as the activity will be maintained even upon storage for periods of months, while using acceptable hydrogen peroxide concentrations.

In order to shield the peroxide based bleaching agent from light, visible light as well as UV light, the film used for producing the package is preferably a multilayer film, which comprises an inner layer of a metal foil and an outer layer of a polymeric film. More preferably however, an inner face of the inner layer of the metal foil is covered with a polymeric film, to avoid direct contact of metal foil with the peroxide compound and to facilitate sealing of the package along the sealing edge, since often use is made of heat sealing for this type of packages. The preferred metal film is aluminium foil, as this material is commercially available in a wide variety of thicknesses and the thin foils easily deform to follow the contours of the object they cover upon application of vacuum. The presence of the metal foil also has the effect that evaporation of water from the bleaching agent is restricted to a minimum. This is important since the bleaching agent will often contain an amount of water.

A wide variety of polymers may be used as polymer film material, and they are well known to the skilled person. Preferred materials include ethylene vinyl alcohol copolymer (EVOH), polyamide (PA), polyethylene terephthalate (PET), olefins, low density polyethylene LDPE or linear low density polyethylene LLDPE.

Other typical examples of polyolefins suitable for use with the present invention include different grades of polyethylene or polypropylene or ethylene-propylene copolymers, but other heat-sealable polymers can be applied as well e.g. heat-sealable PET. The term "linear polyethylene" refers to homo- or co-polymers of ethylene having one or more co-monomers from the group of C4 tot C10 alpha olefins, such as 1-butene, octene etc., in which the co-polymer molecules are built up of long polymer chains with a small number of branches or cross-linking structures. This in contrast to the standard polyethylenes, which show a high degree of branching. With "linear medium density polyethylene" is meant a linear polyethylene with a density between about 0.93 and 0.94 g/cm³. With "linear high density polyethylene" is meant a linear polyethylene with a density between 0.940 and 0.965 g/cm³.

Polyamide designates polyamides as well as copolyamides, i.e. polymers containing amide bonds (-CONH-) in the polymer chain. Suitable polyamides include nylon 6, nylon 11 , nylon 66, nylon 610, nylon 612, nylon 6/66, amorphous polyamide and the like. Commercially available grades include those made available by DMS as Akulon® and

Stanyl®, by Honeywell as Oxyshield®, by EMS Switzerland as Grivory(R), Grilon(R) and Grilamid(R) as well as MXD-6 polyamide and its derivatives from Mitsubishi, Japan. Amorphous polyamides suitable for use with this invention include polyamides that exhibit no endothermic crystalline melting peak, when determined by the differential calorimetry (DSC). Examples of such polyamides include those manufactured form hexamethylenediamine, 2- methylpentamethyledediamine, 2,2,4-trimethylhexamethylenediamine, 2,2,4- trimethylhexamethylenediamine, bis(4-aminocyclohexyl)methane, 2,2-bis(4- aminocyclohexyOisopropylidene, 1 ,4-diaminocyclohexane, 1 ,3- diaminocyclohexane, methaxylylene diamine, 1 ,5-diaminopentane, 1 ,4- diaminobutane, 1 ,3-diaminopropane, 2-ethyldiaminobutane, 1 ,4- diaminomethyl- cyclohexane, p-xylylenediamine, m-phenylenediamine, p- phenylenediamine, alkyl- substituted m-phenylenediamine and p- phenylenediamine. Examples of suitable polyamides include those manufactured from di- carboxylic acids chosen from the group of isophthalic acid, terephthalic acid, alkyl-substituted isophthalic and terephthalic acids, adipic acid, sebacic acid, butanedicarboxylic acid and the like. Suitable "semi- crystalline polyamide" are polyamides, the crystalline melting point of which can be determined by a standard method in certain conditions, for example nylon 6, nylon 11 , nylon 12, nylon 66, nylon 69, nylon 610, nylon 612, MXD6, nylon 6/66, nylon 6/12, nylon 6/66 copolymer, nylon 66/610 copolymer, nylon 6/69 copolymer and blends thereof. An example of a multilayer film suitable for use with the present invention is Scotchpak® available from 3M, which is a translucent high barrier polyester (PET) based film with a heat-sealable polyolefin layer. These films contain a ceramic oxide coating (AIOx) which provides a strong barrier to moisture and oxygen, as well as UV blocking without the use of metal foils.

To achieve that the packaging film easily conforms to the contents it surrounds, the film has a limited thickness, which is preferably below 5 μm, more preferably below 1 μm, but the film may have a thickness below 500 nm or below 300 nm. A film with such a thickness is capable of conforming to the form of and of surrounding its contents when applying vacuum to the inner volume of the package. This way the package is capable of functioning as a cover for the bleaching agent, to maintain the bleaching agent in the through.

The bleaching agent contained in the applicator preferably comprises hydrogen peroxide. The bleaching composition will usually contain a sufficient amount of hydrogen peroxide to achieve good bleaching results, in particular at least 5 wt. % and usually up to 35 wt. %, or 40 wt. % or even 50 wt. %. According to a practical embodiment the hydrogen peroxide concentration will usually vary between 5 and 40 wt. % with respect to the weight of the composition, preferably between 5 and 36 wt. %depending on the envisaged bleaching effect.

Hydrogen peroxide is usually used in an admixture with a viscosity enhancing agent, to ensure that the viscosity of the bleaching composition is high enough to prevent if from flowing from the through and to prolong tooth contact. According to the invention, a wide variety of viscosity modifiers may be used, but preferably use is made of silicagel as this is a substantially inert compound, which is easily miscible with hydrogen peroxide and which can easily be rinsed off with water. Silicagel presents the advantage of being a good water absorbent and this way promotes the bleaching activity of the bleaching composition. It will usually be present in an amount of between 10 and 50 wt. %.

This way a bleaching agent is obtained which takes the form of a thick paste, which may be contained in the through in a convenient manner at minimum risk to flowing from the through.

If so desired, other viscosity enhancing agents may be used either in admixture with silicagel or as such, such as for example carbomers. Carbomers are well known to the skilled person, and include homopolymers and copolymers of acrylic acid, crosslinked with an allyl ether pentaerythritol, allyl ether of sucrose or allyl ether of propylene. Suitable carbomers are available from CarboMer and from Lubrizol. The viscosity enhancing agent will usually be present in an amount which varies from 1-10 wt. %, depending on the envisaged viscosity. Suitably the viscosity enhancing agent is used in the form of a powder, as this permits obtaining a paste.

The bleaching agent may further contain any other component considered useful by the skilled person, such as colourants, a complexing agent for any metal ions present in the composition.

The bleaching agent will further usually contain an amount of water, to facilitate mixing and achieve homogeneous distribution of all ingredients. The water content will usually vary between 40 and 75 wt. %.

The bleaching agent further preferably comprises a base in order to provide the bleaching composition with a neutral to alkaline pH, since hydrogen peroxide stability is improved in alkaline conditions. Preferably the pH of the bleaching agent is at least 7, more preferably between 7.5-8.5 as this does not adversely affect the pH of the mouth cavity.

The applicator which contains the bleaching composition may be made of a wide variety of materials, which are transparent to UV light to permit irradiation of the bleaching composition with the applicator positioned over the teeth. The material for the applicator is preferably at the same time sufficiently flexible to permit accommodating dental arches of varying shapes and dimensions, to avoid that it must be custom made, and has a low porosity to minimise the risk to absorption of the bleaching composition by the applicator. Preferably, use is made of a transparent thermoplastic elastomer. Suitable thermoplastic elastomers include those selected from the group of styrene butadiene copolymers, thermoplastic polyurethane, preferably polyurethane made from poly(propylene glycol)-block-poly(ethylene glycol) polyols, polyether block amides and styrene-ethylene butylene-styrene copolymers, polyether-polyamide, for example Vestamid.

An evaluation method of the oxygen barrier typical in the field is to measure the oxygen permeability of a material in a time unit. The determinations are made in standard temperature and humidity conditions. The usual determination conditions comprise a temperature of 23°C

/ relative humidity of 0%, a temperature of 23°C / relative humidity of 60%, and a temperature of 23°C / relative humidity of 85%. Equipment designed for the purpose, e.g., Ox-T ran 2/20 (Oxygen Transmission Rate Measurement Rate Measurement System), Mocon, Minneapolis, USA, is used to measure the oxygen flowing through a sample from one chamber to another, and it is given in a unit of cm³/m².d.b. Detailed information of the determination is given, e.g., by the American National Standards Institute by means of the standard method ASTM D 3985.

Packaging of the dental applicator in the above described multi-layer film may be done in several ways, the skilled person will be capable of selecting the most appropriate technique taking into account the viscosity of the bleaching agent contained in the applicator and the dimensions of the applicator. According to a first embodiment, use is made of a single sheet, which is double folded to receive the dental applicator in its interior. The edges of the sheet are sealed in such a way that at least one opening is left along which vacuum may be applied to the interior of the package. After a sufficient vacuum has been achieved, sealing of any remaining openings may be completed. According to another embodiment, use is made of a first and a second multi-layer film. The dental applicator is positioned upon an inner face of the first sheet, the second sheet is positioned on top of the applicator. The first and second sheet are connected to each other along their edges in such a way that at least one opening is left along which vacuum may be applied to the interior of the package. After a sufficient vacuum has been achieved, sealing of any remaining openings may be completed. Sealing of the edges may be achieved by applying heat and heat sealing the polymer, or by using a suitable adhesive, or according to any other technique considered suitable by the skilled person. The invention is further elucidated in the accompanying figure and figure description.

Figure 1 shows a view to the applicator used in the kit of the present invention.

As can be seen from figure 1 the applicator comprises a first and a second upright wall 1 , 2 on opposite sides of a trough

5. The through is provided for immersing teeth of at least one dental arch and contains a preset amount of a bleaching agent 10 for immersing teeth. If so desired, the applicator may be made to fit to either the upper or lower dental arch only, but it is preferably made to fit to both arches simultaneously, as is shown in figure 1. To that end, the applicator will usually comprise a first through 5 which is open towards the upper dental arch and a second through 6 which is open towards the lower dental arch. The second, lower through is delimited on opposite sides by a third and fourth upright side 3, 4 wall. A front part of the applicator preferably comprises a lens 6, with the purpose of capturing UV-light upon irradiation with an appropriate UV light source and of distributing the captured light over the part of the dental arch covered by the applicator. In stead of UV-light, use may be made of a laser source with an appropriate wavelength of between 400 and 550 nm. Teeth of an upper dental arch are received in the first through 5 and immersed in the bleaching agent contained therein, teeth of a lower dental arch are received in the second through 6 and immersed in the bleaching agent received therein. Following immersion of the teeth, the applicator, in particular lens 7 is irradiated with an appropriate light source. The lens 7 functions to distribute the light in width en height direction of the dental applicator.

The applicator is received in a package. The package is usually formed by positioning the dental applicator positioned upon an inner face of a first sheet, and by positioning a second sheet on top of the applicator. The first and second sheet are connected to each other along their edges. At least one opening is left along which vacuum is applied to the interior of the package. After a sufficient vacuum has been achieved, sealing of any remaining openings may be completed. Upon application of vacuum, the film will deform to follow the shape and contours of the dental applicator.

Claims

CLAIMS.

1. A kit comprising a dental applicator provided for insertion in the mouth, the applicator having a first and a second upright wall on opposite sides of a trough, the through containing a preset amount of bleaching agent for bleaching teeth and being provided for receiving and permitting immersion of the teeth of at least one dental arch in the bleaching agent, the kit further comprising a package for the dental applicator with an inner volume in which the dental applicator is received, characterised in that the package is sealed along at least one closure edge, in that the package is made of a material comprising a film, which is impermeable to visible and UV light and comprises an oxygen barrier, and in that the inner volume of the package is maintained under reduced oxygen pressure.

2. A kit as claimed in claim 1 , characterised in that in the inner volume of the package an oxygen pressure is maintained which is below 2 %, preferably below 1 %, more preferably below 0.6 %, most preferably below 0.5 %.

3. A kit as claimed in claim 1 or 2, characterised in that the film is a multilayer film comprising an inner layer of a metal foil and an outer layer of a polymeric film.

4. A kit as claimed in claim 3, characterised in that as a metal film use is made of aluminium foil.

5. A kit as claimed in claim 3 or 4, characterised in that the polymer film is made of a material selected from the group of ethylene vinyl alcohol copolymer (EVOH), polyamide (PA), polyethylene terephthalate (PET), low density polyethylene LDPE or linear low density polyethylene LLDPE.

6. A kit as claimed in any one of claims 1-5, characterised in that the film has a thickness of below 5 μm, preferably below 1 μm.

7. A kit as claimed in any one of claims 1-6, characterised in that the bleaching agent comprises 5-40 wt. % of hydrogen peroxide as bleaching agent.

8. A kit as claimed in any one of claims 1-7, characterised in that the bleaching agent comprises silicagel.

9. A kit as claimed in any one of claims 1-8, characterised in that the bleaching agent comprises a base, in particular sodiumhydroxide.

10. A kit as claimed in any one of claims 1-9, characterised in that the applicator is made of a transparent thermoplastic elastomer.

1 1. A kit as claimed in claim 10, characterised in that the thermoplastic elastomer is selected from the group of styrene butadiene copolymers, thermoplastic polyurethane, preferably polyurethane made from poly(propylene glycol)-block-poly(ethylene glycol) polyols, polyether block amides and styrene-ethylene butylene -styrene copolymers.

12. A kit as claimed in any one of claims 1-1 1 , characterised in that the first and second upright wall are provided to shield periodontal tissue surrounding the teeth subject to contact with the bleaching composition.