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Title:
TOOTH WHITENING COMPOSITION AND METHOD
Document Type and Number:
WIPO Patent Application WO/2011/161240
Kind Code:
A2
Abstract:
A combined preparation is described comprising a first sodium or postassium hydroxide and xylitol aqueous solution, a second hydrogen peroxide aqueous solution and a third aqueous solution containing sodium or potassium hydroxide, a fluoride salt, hydroxyapatite and xylitol. Said preparation can be advantageously used in tooth whitening cosmetic methods without causing the undesired effects generally associated to the use of hydrogen peroxide.

Inventors:
MARINO, Elio (Via Strafavia 7, Saronno, I-20147, IT)
Application Number:
EP2011/060623
Publication Date:
December 29, 2011
Filing Date:
June 24, 2011
Export Citation:
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Assignee:
OCSLABO-ORALCARESCIENCELABO S.A.G.L. (Via Cantonale 6, Lugano, CH-6900, CH)
MARINO, Elio (Via Strafavia 7, Saronno, I-20147, IT)
International Classes:
A61K8/19; A61K8/21; A61K8/22; A61K8/24; A61K8/34; A61Q11/00
Attorney, Agent or Firm:
ASENSIO, Raffaella, Consuelo et al. (Perani & Partners S.p.A, Piazza San Babila 5, Milano, I-20122, IT)
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Claims:
CLAIMS

1) A tooth whitening combined preparation comprising:

a) a first aqueous solution (Solution 1) comprising sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w (weight/total weight of the solution) and xylitol at a concentration of 0.4 to 0.6% w/w;

b) a second aqueous solution (Solution 2) containing hydrogen peroxide at a concentration of 15 to 35% v/v (volume/ total volume of the solution);

c) a third aqueous solution (Solution 3) comprising sodium hydroxide or potassium peroxide at a concentration of 0.05 to 0.5 w/w, a fluoride salt at a concentration of 0.4 to 1 % w/w, hydroxyapatite at a concentration of 0.4 to 1 % w/w and xylitol at a concentration of 0.4 to 1% w/w.

2) The composition according to claim 1 wherein the second solution contains hydrogen peroxide at a concentration of 19% or 35% v/v of the composition.

3) A cosmetic method of tooth whitening comprising the following steps:

a) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 1) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w and xylitol at a concentration of 0.4 to 1% w/w to obtain a pH of at least 6.8 on the dental surface and oral mucosa;

b) applying (once or repeating 2 to 5 times) to the dental and gingival surface and 40 - 60 microliters of an aqueous solution (Solution 2) containing hydrogen peroxide at a concentration of 15 to 35% v/v;

c) rinsing the mouth with water;

d) repeating steps a) - c) for at least 1 to 5 additional times;

e) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 3) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5%) w/w, a fluoride salt at a concentration of 0.4 to 1% w/w, hydroxyapatite at a concentration of 0.4 to 1% w/w and xylitol at a concentration of 0.4 to 1% w/w to obtain a pH of at least 7 on the dental surface and oral mucosa.

4) The method according to claim 3 wherein the Solution 2 (step b) is held on the dental and gingival surface for 60 seconds.

5) The method according to claim 3 or 4 wherein 15 ml of the Solution 1 (step a) and 15 ml of the Solution 3 (Step e) are used and rinsing is carried out for 30 seconds.

6) The method according to claim 5 wherein the treatment is carried out for 5 to 18 consecutive days.

7) The method according to one of the claims 3-6 wherein the application of Solution 2 in step b) is performed by spraying.

8) The method according to one of claims 4-7 wherein the hydrogen peroxide concentration in Solution 2 is selected in an interval ranging from 19% to 35% v/v.

9) The method according to one of claims claim 5-8 further including a maintenance/remineralization cycle including the following steps following step e): f) rinsing the mouth with 5 - 30 ml of Solution 3 for 20 - 40 seconds;

g) applying (once or repeating 2 to 5 times) 40 - 60 microliters of Solution 2 on the dental and gingival surface and spit;

h) rinsing the mouth with water;

i) rinsing the mouth with 5 - 30 ml of Solution 3 for 10 - 60 seconds to obtain a pH of 7 or higher.

10) The method according to any of claims 1-9 further comprising the step of applying a layer of a protective lip balm to the lips prior to step a)

11) A kit for tooth whitening comprising the combined preparation of claim 1.

12) The kit of claim 11 further comprising a protective lip balm.

13) A cosmetic method of tooth whitening comprising the following steps: a) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 1) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w and xylitol at a concentration of 0.4 to 1% w/w to obtain a pH of at least 6.8 on the dental surface and oral mucosa;

b) applying to the dental surface a tooth whitening agent(Carbamide Peroxide, Hydrogen Peroxide, or similar substances );

c) rinsing the mouth with water;

d) repeating steps a) - c) for at least 1 to 5 additional times;

e) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 3) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5%) w/w, a fluoride salt at a concentration of 0.4 to 1% w/w, hydroxyapatite at a concentration of 0.4 to 1% w/w and xylitol at a concentration of 0.4 to 1% w/w to obtain a pH of at least 7 on the dental surface and oral mucosa.

Description:
"Tooth whitening composition and method" Field of the invention

The present invention relates to a tooth whitening combined preparation and a tooth whitening cosmetic method including the use of such preparation.

State of the art

The use of hydrogen peroxide as an ingredient in compositions for use in tooth whitening methods has been known for a long time.

The effectiveness of such compositions is higher the higher the concentration of ion peroxide (HOO ), which is the active species.

Hence, a first approach to increase the whitening (or bleaching) effect may be to increase the concentration of hydrogen peroxide in the composition. However, it must be considered that the concentration of hydrogen peroxide allowed in toothpastes and mouthwashes is generally 0.1%, a concentration considered safe for the consumer, while concentrations of hydrogen peroxide above 6% are considered not safe, unless it is demonstrated that the amount of hydrogen peroxide actually released in the saliva and on the gums does not exceed that released from products containing 6% hydrogen peroxide. This is due to the fact that administration of compositions containing hydrogen peroxide at a concentration of 0.1 to 6% volume/total volume of the composition (hereafter v/v) may cause some undesired effects, such as re-exacerbation of gingivitis or other periodontal diseases in predisposed subjects, for example in smokers or subjects consuming considerable amounts of alcohol.

The accidental application of a concentrated hydrogen peroxide solution to the oral mucosa and to the lips can cause burns and inflammation of the tissues, caused by the oxidising action of H 2 0 2 and by the acidic pH of the composition. Furthermore, particular attention must be paid to the use of hydrogen peroxide-based products immediately before or after treatments of tooth restoration in children and adolescents. Finally, accidental ingestion of hydrogen peroxide-containing products may have irritating effects on the oral cavity and gastrointestinal tract.

A second approach to increase the effectiveness of hydrogen peroxide-based whitening compositions is the addition of an alkalinizing agent. However, due to the scarce stability of hydrogen peroxide in a basic environment, it is not possible to prepare alkaline hydrogen peroxide solutions in advance.

A whitening product consisting of two phases has been placed on the market in the United States: a liquid form composition containing 1.5% hydrogen peroxide and a liquid form composition containing 10% sodium bicarbonate; such compositions are mixed at the time of use through a suitable dispenser and, shortly after, are applied on the dental surface and adjacent mucosa.

The use of dental whitening product has been linked also to damages of the dental surface, in particular of the enamel, such as root resorption, reduction in bond strength and demineralization which eventually results in change in micro-hardness (Joiner A. J. Dent. 2007 Dec;35(12):889-96, Epub 2007 Oct 26; Grobler S. R., Majeed A., Moola M. H. SAD J. 2009 Nov;64(10):474-9; Attin T, Schmidlin PR, Wegehaupt F, Wiegand A. Dent Mater. 2009 Feb;25(2):143-57. Epub 2008 Jul 16) and in roughness and morphology (Pinto CF, Oliveira R, Cavalli V, Giannini M. Braz Oral Res. 2004 Oct- Dec;18(4):306-l l).

These effects could be related to the presence of residual hydrogen peroxide in the interprismatic spaces as well as in the dentinal matrix and tubules. In addition, demineralisation and erosion of the tooth substance is known to be particularly favoured in an acidic environment (e.g. pH 4.4) such as that created after treatment of the dental surface with compositions containing hydrogen peroxide. If these processes are not effectively and quickly stopped, the erosion can penetrate the dentine and lead to loss of tooth substance.

Tooth enamel is a unique mineralized tissue in that it is acellular, is more highly mineralized, and is comprised of individual crystallites that are larger and more oriented than other mineralized tissues. Dental enamel forms by matrix-mediated bio- mineralization. Enamel crystallites precipitate from a supersaturated solution within a well delineated biological compartment. Mature enamel crystallites are comprised of non-stoichiometric carbonated calcium hydroxyapatite. The earliest crystallites appear suddenly at the dentine enamel junction (DEJ) as rapidly growing thin ribbons. The shape and growth patterns of these crystallites can be interpreted as evidence for a precursor phase of octacalcium phosphate (OCP). An OCP crystal displays on its face a surface that may act as a template for hydroxyapatite (OHAp) precipitation. Octacalcium phosphate is less stable than hydroxyapatite and can hydro lyze to OHAp. During this process, one unit cell of octacalcium phosphate is converted into two unit cells of hydroxyapatite. During the precipitation of the mineral phase, the degree of saturation of the enamel fluid is regulated.

Hydroxyapatite is very susceptible to acid attack, for example subject to dilute acid generated from sugar metabolized by the germs in plaque (Larsen M.J., Pearce E.I., Jensen S.J. Caries Res. 1993; 27(2): 87-95)

Remineralization can be obtained through enamel conditioning when fluoride and fluorapatite are available at the biofilm interface on the enamel surface.

Hydroxyapatite is also quite susceptible to "attack" by free fluoride ions as well, but instead of causing destruction of the hydroxyapatite crystals, it causes their transformation into fluorapatite. The fluoride ions essentially substitute themselves for the hydroxyl groups in the hydroxyapatite.

Remineralization is the physiologic reaction product of enamel/apatite fluoridation after topical application of fluoride.

Fluorapatite has most of the same characteristics as hydroxyapatite, but is quite resistant to attack by acid.

Hydroxyapatite replacement with fluorapatite is driven at high pH (Pearce E.I. Proc Finn Dent Soc. 1991;87(4) 527-39, Aoba T., Shimazu Y., Taya Y., Soeno Y., Sato K., Miake Y. J Electron Microsc (Tokyo) 2003;52 ¾ ) :615-25;.

US 2006/0204455 discloses an enhancing composition comprising a solvent and a base compound such as potassium hydroxide for activating peroxide whiteners, which can be used for advance application to the dentition before a whitening compound.

WOOO/48563 discloses a method for effecting heightened whitening of teeth wherein there is first applied to the teeth an aqueous rinse composition having an alkaline pH and thereafter brushing the teeth with a peroxide dentifrice.

US2009/0253101 discloses a method and apparatus that allows high concentrations of hydrogen peroxide for tooth whitening by use of an aerosol spray which may be delivered through a mouthpiece onto the teeth.

An object of the present invention is to provide a preparation suitable for tooth whitening that is stable over time and that can release the whitening agent with the highest efficacy on the dental surface.

Another object of the present invention is to provide a method of tooth whitening that is safe, easy to use also for the non-healthcare professionals and with maximum bleaching activity. Summary of the invention

It has now been found that it is possible to increase significantly the concentration of hydrogen peroxide in use to obtain an improved whitening effect without causing the above undesired effects.

These objects have been achieved via a combined preparation for tooth whitening comprising a first aqueous solution (Solution 1) comprising sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w (weight/total weight of the solution) and xylitol at a concentration of 0.4 to 0.6%> w/w, a second aqueous solution (Solution 2) containing hydrogen peroxide at a concentration of 15 to 35% v/v (volume/ total volume of the solution); and a third aqueous solution (Solution 3) comprising sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5%> w/w, a fluoride salt at a concentration of 0.4 to 1% w/w, hydroxyapatite at a concentration of 0.4 to 1% w/w and xylitol at a concentration of 0.4 to 1% w/w.

The objects of the invention have also been achieved via a kit comprising said combined preparation.

These objects have been achieved also via a cosmetic method of tooth whitening comprising the following steps:

a) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 1) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w and xylitol at a concentration of 0.4 to 0.6% w/w to obtain a pH of at least 6.8 on the dental surface and oral mucosa;

b) applying (once or repeating 2 to 5 times) to the dental and gingival surface 40 - 60 microliters of an aqueous solution (Solution 2) containing hydrogen peroxide at a concentration of 15 to 35% v/v;

c) rinsing the mouth with water;

d) repeating steps a) - c) for at least 1 to 5 additional times; e) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 3) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w, a fluoride salt at a concentration of 0.4 to 1% w/w, hydroxyapatite at a concentration of 0.4 to 1% w/w and xylitol at a concentration of 0.4 to 1% w/w to obtain a pH of at least 7 on the dental surface and oral mucosa.

Description of the Figures

Figure 1 : the Vitapan classical (standard "Value" scale for evaluation) and a typical visual score difference example.

Figure 2: the results of a test wherein the visual score difference between pre and post treatment is evaluated comparing three commercial whitening agents and Solution 2 of the invention ("Experimental solution").

Figure 3: methods and materials for evaluation of the remineralizing solutions effect on the Enamel Surface Characteristics.

Figures 4-6: results of the EDX analysis of the enamel surface after treatment with remineralizing solutions.

Figure 7: the scanning electron photographs of enamel surface after the application of the remineralizing solutions, as demonstrated by scanning electron photographs of enamel surface.

Figure 8: effects of the application of enamel surface conditioner and the application of remineralizer solution on the tooth colour change and the enamel surface characteristics. Figures 9-12: EDX analyses of the enamel surface after the application of enamel surface conditioner and the application of remineralizer solution.

Figure 13: scanning electron photographs of enamel surface with the application of enamel surface conditioner and with the application of enamel remineralizer solution (group 1). Figure 14: scanning electron photographs of enamel surface with the application of enamel surface conditioner only (Group 2) (Left), with the application of enamel remineralizer solution only (Group 3) (Middle), and no treatment (Group 4) (Right). Figure 15: results relative to colour change of teeth exposed to different bleaching solutions with the application of an enamel remineralizer rinse solution.

Figure 16: Representative photograph of colour data gathered by spectrophotometer: (a) group L, (b) group Gel-X and (c) group Gel-G. Each picture illustrates the different colour between the experimental bleach tooth (left) and the non bleached tooth (right). Figure 17: EDX analyses regarding the elemental composition (Ca, O, P), recorded in % by weight on the enamel surface.

Figure 18: representative SEM micrographs of enamel surface in group L (a) non bleached or control and (b) bleached part of the same tooth (original magnification xlOOO).

Figure 19: representative SEM micrographs of enamel surface in group Gel-X (a) non bleached or control and (b) bleached part of the same tooth (original magnification xlOOO). Notice: there is some remaining remineralizer deposited on the enamel surface. Figure 20: representative SEM micrographs of enamel surface in group Gel-G (a) non bleached or control and (b) bleached part of the same tooth (original magnification xlOOO).

Figure 21 : results in terms of average visual score difference and of mean (SD) tooth colour difference (ΔΕ).

Figure 22: results in terms of average visual score difference and of mean (SD) tooth colour difference (ΔΕ).

Figure 23: results in terms of average visual score difference and of mean (SD) tooth colour difference (ΔΕ). Figure 24: measurement of pH in the mouth during application of the method of invention

Figure 25 : evaluation of the degree of satisfaction obtained by use of the method of the invention.

Detailed description of the invention

Unless otherwise specified, concentration of the hydrogen peroxide solutions are in volume of hydrogen peroxide/ total volume of the solution.

Equation 1 explains the direct connection between pH and the peroxide radical creation c(HOQ) hydrogen a- oxide anion conc ntration

pH pH at real oper ation temperature

pK a value of hydrogen peroxide [17, 18]

ciHOa + HOOH) total hydrogen peroxide ncentration (r esult of the titration)

activity coefficient of univalent ion (typically about 0.8 in ionic strengths of hydrogen peroxide bleaching)

The equation clearly shows that, for a given pH level in the range pH 9- 13, the decomposition reaction is first-order with respect to total peroxide concentration.

The pH of these solutions is not observed to vary significantly during the initial course of radical peroxide formation reaction, that is up to 5% conversion. Under alkaline conditions, the decomposition of hydrogen peroxide has been attributed to an uncatalyzed, homogeneous bimolecular reaction involving the perhydroxy anion, H0 2 ~ . The active bleaching species associated with hydrogen peroxide is the perhydroxyl anion, HOO . The reversible equilibrium which determines the concentration of this anion is described by On the other hand, the cation H 3 0 is also in equilibrium with OH from the dissociation of water:

2¾0^¾0 + + OH (2)

Thus any increase in OH concentration depresses the level of H 3 0 (eq.2) and, consequently, raises the concentration of the HOO in equilibrium with it (eq. l). This implies that bleaching will occur more rapidly as the solutions of hydrogen peroxide are made more alkaline.

H 2 0 2 is more stable, and thus has a longer shelf life, in acidic solutions, but it is reactive as a bleaching agent at pH values closer to its dissociation constant (1.5 x 10 ~12 at 20°C), which means that the peroxide radical is liberated at very alkaline pH.

H 2 O 2 in aqueous solutions has an acidic pH, for example a 35% solution (v/v) has a pH value of 4.4.

The irreversible decomposition of hydrogen peroxide, on the other hand, is described by

Bleaching is not caused by the decomposition reaction.

The acidic pH of the H 2 O 2 , when applied to the dental surface, can cause demineralisation and erosion of the tooth substance. If this process is not effectively stopped or prevented, the erosions can damage the dental surface and eventually penetrate the dentine, ultimately leading to loss of the tooth substance.

It was surprisingly found that it is possible to maximise the teeth bleaching action of

H 2 O 2 without exposing the dental surface to risks deriving from erosion and demineralisation.

In a first aspect, the present invention relates to a tooth whitening combined preparation comprising:

a) a first aqueous solution (Solution 1) comprising sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w (weight/total weight of the solution) and xylitol at a concentration of 0.4 to 0.6% w/w;

b) a second aqueous solution (Solution 2) containing hydrogen peroxide at a concentration of 15 to 35% v/v(volume/ total volume of the solution); c) a third aqueous solution (Solution 3) comprising sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5%> w/w, a fluoride salt at a concentration of 0.4 to 1% w/w, hydroxyapatite at a concentration of 0.4 to 1% w/w and xylitol at a concentration of 0.4 to 1% w/w.

In solutions 1 and 3, the preferred concentration of sodium hydroxide is 0.2%, that of xylitol is 0.5%, that of the fluoride salt and hydroxyapatite is 0.55% .

The concentration of hydrogen peroxide in the second solution is, according to a first preferred embodiment of the invention, 35% v/v; such concentration is particularly well suited when the whitening treatment is carried out under professional control. In a second embodiment of the invention, Solution 2 contains 19% v/v of hydrogen peroxide; such solution is particularly well suited as a maintenance treatment or for at- home use.

Each solution may contain additional ingredients suitable for human administration. In particular, solutions 1 and 3 may also contain moisturizing agents, solubilizing agents, flow agents, preservatives, colours and flavours, while Solution 2 may contain ethanol, phosphoric acid and parabens as stabilizing substances. As moisturizing agents sorbitol and glycerine can be mentioned; as solubilizing agents castor oil polyethylene glycols, for example castor oil-PEG 40 and vinylpyrrolidone/ammonium acryloyldimethyltaurate copolymer can be mentioned; as a preservative cetyl- benzalkonium chloride can be mentioned. Advantageously, possible colours will be chosen in order to give the solutions different colourings, to facilitate their recognition by the user.

A preferred example of Solution 1 has the following composition: Ingredient Amount (percentage in weight)

Purified water 91.21

Sorbitol 3.0

Glycerin 3.0

Brilliant green bio colour 1% w/w LFS (INCI-EU code Aqua-CI 42090 - CI 19140) 1.0 Hydrogenated castor oil-PEG 40 0.5 Xylitol 0.5

Sodium hydroxide 0.2 Benzalkonium chloride 0.2 Teeth and gums flavour T1000840 0.1 Mint flavour GH- 1069 0.1 Cetyl-pyridinium chloride 0.07 Sodium saccharine 0.07 Menthol 0.05 Total 100.00

A preferred example of Solution 2 is the aqueous solution commercially known with the trademark Peroxal® comprising up to 30-35 hydrogen peroxide.

A preferred example of Solution 3 has the following composition: Ingredient Amount (percentage in weight) Purified water 89.71 Sorbitol 3.0 Glycerin 3.0

Vinylpyrrolidone/acryloyldimethyl taurate copolymer 0.8 Hydrogenated castor oil derivatized with PEG40 0.7 Sodium fluoride 0.55 Hydroxyapatite 0.55 Xylitol 0.5

Sodium hydroxide 0.2

Bio colour FD&C blue 1-Puricolour ABL 9 (INCI code CI 42090) 0.2 Benzalkonium Chloride 0.2 Flavour 0.2

Mint flavour GH-1069 0.2 Cetyl-pyridinium chloride 0.07 Sodium saccharine 0.07 Menthol 0.05 Total 100.00

Solutions 1 - 3 may be readily prepared by a skilled technician by means of conventional methods.

The combined preparation according to the invention may be marketed in the form of a kit, for example containing the three solutions in 5 different bottles, the second solution being contained in a bottle suitable to be connected with a supplier device allowing to dispense 50 microliters doses.

Alternatively, the combined preparation according to the invention may be already contained in a supplier bottle allowing to dispense such doses. Furthermore, the kit may possibly contain a lip balm or a protective lip cream. For example, the lip balm or lip cream may comprise paraffmum liquidum, cera alba, mirowax, vitamin E, bisabolol and aroma. Preferably, the lip balm is in the form of a lipstick.

In another aspect, the invention relates to a cosmetic method of tooth whitening comprising the following steps:

a) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 1) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w and xylitol at a concentration of 0.4 to 0.6% w/w to obtain a pH of at least 6.8 on the dental surface and oral mucosa;

b) applying (once or repeating 2 to 5 times) to the dental and gingival surface 40 - 60 microliters of an aqueous solution (Solution 2) containing hydrogen peroxide at a concentration of 15 to 35% v/v;

c) rinsing the mouth with water;

d) repeating steps a) - c) for at least 1 to 5 additional times;

e) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 3) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w, a fluoride salt at a concentration of 0.4 to 1% w/w, hydroxyapatite at a concentration of 0.4 to 1% w/w and xylitol at a concentration of 0.4 to 1% w/w to obtain a pH of at least 7 on the dental surface and oral mucosa.

The initial application of an alkaline mouth rinse (Solution A) creates an alkaline environment on the dental surface and oral mucosa before the usage of H 2 0 2 bleaching agent. Raising the pH to 9 before administration of the bleaching agent increases the dissociation rate of the peroxide radical producing an increase in tooth whiteness of approximately 2.7 times with respect to the whiteness obtained by applying H 2 0 2 at pH of 4.4 (standard 35% v/v solution) during identical exposure periods (Example 1).

This allows also a significant reduction in the time of exposure to H 2 0 2 while obtaining the same bleaching effect, thus reducing the harmful side effects of H 2 0 2 to the dental surface and to the oral mucosa.

This is achieved by application of small volumes (40-60 microliters) of an aqueous solution comprising hydrogen peroxide (Solution 2) at a concentration of 15 to 35 v/v. Preferably, Solution 2 is held in contact with the dental and gingival surface for a short period of time, e.g. 30-60 seconds. A period of 30 sec is preferable to minimize any possible side effect concern, while a period of 60 seconds is preferable for maximum bleaching effect.

The application of Solution 2 on the dental surface pre-conditioned to pH 9 in step a) of the method maximises the rate of formation of the peroxide radical, thus enhancing the bleaching action in a very short time.

The final treatment with Solution 3 performs various beneficial actions. Firstly, it equilibrates the pH in the mouth with a buffering action over the acidic pH obtained after application of concentrated hydrogen peroxide (Solution 2).

Experimental data in human (Example 2) demonstrate that the pH of the mucosa increased to 7.0 (standard deviation, sd, ±0.2) after step a) of the method, decreased to 4.9 (sd +0.3)after treatment with Solution 2 and increased again to 7.5 (sd +0.3) after rinsing with Solution 3.

It was found that, besides blocking the erosion of the dental surface due to the acidic pH, shifting the pH to neutral/slightly basic values after application of concentrated hydrogen peroxide promotes further production of peroxide radical from the residual H 2 0 2 present on the tooth surface, thus eliminating the risk of penetration of H 2 0 2 in the dentine and producing an extra increase in tooth whitening.

Furthermore, Solution 3 has an anticavity and remineralizing action because fluoride, xylitol and hydroxyapatite protect against demineralization and erosion of the tooth. It has been surprisingly found that the application of Solution 3 in the method of the present invention actually promotes remineralisation and actively restores the smoothness of the enamel surface, contrasting the adverse action of the acidic bleaching solution. Experimental data using Solution 3 (Example 3) reveal higher percentages of calcium ion deposit on tooth enamel when compared to a commercial remineralizing paste (Mi-Paste) and to a control group. Porosity of the enamel is also reduced by the application of Solution 3 after the bleaching step.

The anticavity effect is further achieved by the presence of xylitol, an antagonist of sugars which prevents the growth of bacteria responsible for the formation of plaque and accelerates the remineralization of damaged teeth.

The treatment defined at steps a) and e) may be carried out for 5 - 7 consecutive days, but it may also be carried out for a lower or higher number of days, e.g. from 9 to 18 days, in consideration of the pigmentation of the subject's teeth and of the desired degree of whitening.

Additionally, according to a preferred embodiment of the invention, step a) may be advantageously preceded by the application of a protective cream or balm on the lips, in order to protect them from the possible irritating effect of the solutions.

When the treatment is carried out by a professional, a Solution 2 containing 35% v/v of hydrogen peroxide will be used, while when the treatment is carried out as a maintenance and/or at-home treatment, a Solution 2 containing 19% hydrogen peroxide will be used. Preferably, in the method of the invention, Solution 2 of step b) is applied by spraying on the gingival and dental surface.

According to a further embodiment of the invention, the method may include a further cycle of maintenance/remineralization to be carried out with Solution 3 after carrying out steps a) - e) for a predetermined number of days; such cycle includes the following steps: f) rinsing the mouth with 5 - 30 ml, preferably 15 ml, of Solution 3 for 20 - 40 seconds, preferably 30 seconds; g) repeatedly spraying, preferably from once or repeating 2 to 5 times, 40 - 100 microliters, preferably 50 microliters, of Solution 2 on the teeth and spit; h) rinsing the mouth with water; i) rinsing the mouth with 5 - 30 ml, preferably 15 ml, of Solution 3 for 20 - 40 seconds, preferably 30 seconds.

The method according to the invention allows to obtain an increase of the whitening effect of at least 50% and up to 2.7 times in comparison with treatments carried out keeping the mouth pH around the normal value of 6.5, without causing the undesired effects commonly associated to whitening with hydrogen peroxide. In particular, neither an increase of dentinal sensitivity nor any phenomenon of enamel erosion are observed.

The improved effect of the combined preparation according to the invention is due to the fact that sodium hydroxide in Solution 1 allows to increase the pH of the oral cavity to a value of at least 6.8, thus promoting the dissociation of hydrogen peroxide contained in Solution 2 and increasing its effectiveness. In fact, by virtue of the administration of Solution 1 (conditioning mouthwash), it is possible to administer limited amounts of hydrogen peroxide at high concentrations; for example, performing five sprays of 50 microliters each of 35%> v/v hydrogen peroxide solution, the amount of hydrogen peroxide administered amounts to 87.5 microliters, which correspond to 98.87 milligrams. Hence, by performing five sprays of 50 microliters each and by performing three times steps a) - c), an amount of hydrogen peroxide of about 297 milligrams is administered altogether; considering the mean body weight of an individual being 60 kg, the daily administered amount is 0.005 mg/kg, therefore within the established safety limits. Instead, using a 19% hydrogen peroxide solution and repeating three times steps a) - c), the daily administered amount will be below 0.002 mg/kg.

Sodium hydroxide contained in Solution 3 allows to complete the whitening effect of Solution 2, since it promotes the dissociation of the hydrogen peroxide possibly left in the oral cavity after steps a) - d).

Xylitol in Solutions 1 and 3 minimizes the risk of enamel erosion and promotes remineralization processes; furthermore, in Solution 3, it acts in a synergistic way with the fluoride salt, promoting the deposition of fluorohydroxyapatite in dentinal tubules.

In another embodiment, the present invention relates to a cosmetic method of tooth whitening comprising the following steps:

a) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 1) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5% w/w and xylitol at a concentration of 0.4 to 1% w/w to obtain a pH of at least 6.8 on the dental surface and oral mucosa;

b) applying to the dental surface a tooth whitening agent (Carbamide Peroxide, Hydrogen Peroxide, or similar substances ) ;

c) rinsing the mouth with water;

d) repeating steps a) - c) for at least 1 to 5 additional times;

e) rinsing the mouth for 20 - 40 seconds with 5 - 30 ml of an aqueous solution (Solution 3) containing sodium hydroxide or potassium hydroxide at a concentration of 0.05 to 0.5%) w/w, a fluoride salt at a concentration of 0.4 to 1% w/w, hydroxyapatite at a concentration of 0.4 to 1% w/w and xylitol at a concentration of 0.4 to 1% w/w to obtain a pH of at least 7 on the dental surface and oral mucosa. The following examples are intended to illustrate some typical embodiments of the invention with no intent to limit its scope.

EXAMPLE 1

Evaluation of chroma changes during a new bleaching treatment with spray of 35% v/v hydrogen peroxide: preliminary results

The aim of this study is to evaluate the chroma changes, analyzing the LAB (wherein "L" indicates shine and is the value, the teeth are whiter when the value is high; "A" indicates the amount of red and green and is chroma; "B" indicates the amount of blue and yellow and is colour) of the dental surface after the use of a new bleaching treatment spray of 35% v/v hydrogen peroxide.

The bleaching system consists of three different products:

1. Solution 1 or Primer (applied for 30 seconds, 15 ml) which contains xylitol and prepares the pH of the mouth for the whitening treatment;

2. Solution 2 comprising Hydrogen peroxide 35% v/v whitening solution to be applied with a nozzle applicator to spray directly on the teeth;

3. Solution 3 or Remineralizer (applied for 30 seconds, 15 ml) containing NaOH, fluoride, xylitol and Hydroxyapatite, balancing pH and decreasing tooth porosity and sensitivity.

A group of 18 human subjects with good oral health are selected. Recording of chroma is performed with a high precision spectrophotometer (SpectroShade micro, MHT, Italy) before (time zero, TO) and after nine whitening procedure in nine days (time one, Tl). The chroma is detected on the surface of the upper central (element 2.1) and lateral incisor (element 2.2). The spectrophotometer analyzes over 2 million reference points and calculate the LAB. The results show that the average difference between L at TO and at Tl is 3.11 on the central incisor and 0.042 on the lateral incisor. About the A the value is respectively -0.47 and 0.44, while the B is 0.83 and 0.65. The software of spectrophotometer analyzes also the Delta E, number that can be defined as an indicator set that if it exceeds 2 (two) it means that the changes of chroma are visible to the naked eye. In this case the values are 3.29 for central incisor and 2.86 for the lateral.

The bleaching treatment shows good results in the changes to chroma. The experimental procedure is completed without complications and is well tolerated by the patients.

EXAMPLE 2 pH during a new bleaching treatment with spray of 35% v/v hydrogen peroxide

The aim of this study is to evaluate pH of the dental surface and of the oral mucosa at rest and during the use of a new bleaching treatment spray of 35% v/v hydrogen peroxide.

The bleaching system consists of three different products:

1. Solution 1 (contact time with the oral cavity 30 seconds, volume 15 ml) that contains xylitol and prepares the pH of the mouth for the whitening treatment;

2. Solution 2: 35% v/v hydrogen peroxide whitening solution to be applied with a nozzle applicator to be sprayed directly on the teeth;

3. Solution 3: remineralizer (30 seconds, 15 ml) containing NaOH, fluoride, xylitol and Hydroxyapatite, balancing the pH and decreasing tooth porosity and sensitivity.

A group of 14 human subjects in good oral health conditions are selected. Recording of pH is performed with a portable device used in gastroenterology for 24-hours monitoring of pH of oesophagus and stomach (pH-day 2, Menfis, Italy) on the surface of the upper central incisor before and after the whitening procedure and in the fornix in correspondence of the upper molars during the procedure. The results shows a high variability among the subjects: pH at rest 6.7 (sd+0.5) on the dental surface and 6.6 (sd+0.4) on the mucosa of the upper fornix. Using the Primer pH of the mucosa increases to 7.0 (sd+0.2), with the whitening solution pH decreases to 4.9 (sd+0.3), and with the Remineralizer Solution 3 the pH increases again to 7.5 (sd+0.3). At the end of the procedure pH of the enamel recovers to the initial values while the pH of the mucosa showed a slight increase to 0.5 (sd+0.2).

The experimental procedure has been completed without complications and is well tolerated by the patients: despite the sharp decrease of pH, applying the whitening solution the action of the primer and the remineralizer effectively protects the hard and the soft tissue from damage.

EXAMPLE 3

Colour Stability of Different Bleaching Protocols

Part I: The Effect of Different Bleaching Agents

The aim of this study is to evaluate the tooth colour change after exposure to different bleaching solutions.

Method and materials:

Extracted human third molar teeth are selected for tests.

An experimental solution (Solution 2 comprising 18% H 2 0 2 ) is selected as whitening solution.

Comparative whitening solutions are commercially available Venus White Tooth Whitening Gel™, Crest Whitestrips™, Spraywhite 90™, all applied according to the manufacturer's recommendation.

Tooth colour of pre-treatment and post-treatment is compared using Crystaleye dental spectrophotometer (Olympus America Inc) with reference to the Vitapan classical (standard "Value" scale for evaluation as in Figure 1).

The whitening solution is applied in 10 spray shots, 1.5 ml total volume and held on the dental surface for 1 minute.

As reported in figure 2, the Experimental Solution (Solution 2) gives the highest average Visual score difference between pre and post treatment. Part II: The Effect of the Application of Enamel Remineralizer Solution on the Enamel Surface Characteristics.

Method and materials:

Extracted human third molar teeth are selected for tests.

An experimental solution (Solution 3) is selected as remineralizing solution.

Comparative remineralizing solutions are commercially available MI -Paste™ and WOW Powder Oral Rinse™.

In each test, four different regions of the tooth are differentially treated as follows (Figure 3):

zone 1 no treatment (control);

zone 2 application of an enamel remineralisation solution selected between Mi-Paste™ WOW Powder Oral Rinse™ and Solution 3;

zone 3 application of commercial bleaching agent;

zone 4 application of bleaching agent, then rinse with water and apply an enamel remineralisation solution selected between Mi-Paste™ WOW Powder Oral Rinse™ and Solution 3. As shown in figures 4-6 (EDX analysis of the enamel surface), the application of Solution 3 has the effect of the highest increase in calcium content on the tooth surface.

Figure 7 shows the effects of the application of the remineralizing solutions, as demonstrated by scanning electron photographs of enamel surface.

Application of the Solution 3 according to the present invention results in a smoother surface with lower degree of microporosity.

Part III: The Effect of the Application of Enamel Surface Conditioner on the Tooth Colour Change and the Enamel Surface Characteristics The aims of this in vitro study is to determine the effect of the application of enamel surface conditioner and the application of remineralizer solution on the tooth colour change and the enamel surface characteristics.

Method and materials:

Extracted molar tooth (n=20; 5 per group) are treated as follows:

Group 1

(Rinse & Remineralizer Solution)

Initial colour measurement using Spectrophotometer.

Application of enamel surface conditioner for 1 min.

Application of bleaching solution (H 2 O 2 ) and hold for 1 min.

Rinse with water for 30 seconds.

Repeat the enamel conditioner rinse solution and the application of bleaching solution for 1 more time.

Application of remineralizer solution on tooth surface.

Leave the sample dry at room temperature.

Colour measurement re-evaluation.

Group 2 (rinse only).

Initial colour measurement using Spectrophotometer.

Application of enamel surface conditioner for 1 min.

Application of bleaching solution (H 2 O 2 ) and hold for 1 min.

Rinse with water for 30 seconds.

Repeat the enamel conditioner rinse solution and the application of bleaching solution for one more time.

No application of remineralizer solution.

Leave the sample dry at room temperature.

Colour measurement re-evaluation. Group 3 (remineralizer Solution only).

Initial colour measurement using Spectrophotometer.

Application of bleaching solution (H 2 O 2 ) and hold for 1 min.

Rinse with water 30 seconds.

Repeat the application of bleaching solution for one more time.

Application of remineralizer solution on tooth surface.

Leave the sample dry at room temperature.

Colour measurement re-evaluation.

Group 4 (N/A)

Initial colour measurement using Spectrophotometer.

Application of bleaching solution (H 2 O 2 ) and hold for 1 min.

Rinse with water for 30 seconds.

Repeat the application of bleaching solution for one more time.

Leave the sample dry at room temperature.

Colour measurement re-evaluation.

As shown in Figure 8, the rinse and remineralisation group has a higher average visual score difference with respect to the other groups.

Figures 9-12 show EDX analysis of the enamel surface for each group.

Figure 13 shows scanning electron photographs of enamel surface with the application of enamel surface conditioner and with the application of enamel remineralizer solution

(group 1) and figure 14 shows the scanning electron photographs of enamel surface with the application of enamel surface conditioner only (Group 2) (Left), with the application of enamel remineralizer solution only (Group 3) (Middle), and no treatment (Group 4)

(Right).

Group 1 (with enamel surface conditioner and enamel remineralizer solution) demonstrates the highest score of visual shade difference when compared to other testing groups. Statistical analysis reveals that there is a significant difference in colour change values (ΔΕ) between the testing groups ( =0.02). Group 4 (control; no treatment) demonstrates the lowest of the colour change values.

Part IV: Colour changes of teeth exposed to different bleaching solution with the application of new enamel remineralizer rinse solution (Solution 3)

Methods and materials:

Extracted molar teeth (n=10 per group) are treated as follows:

Group HW-18:

Initial colour measurement using Spectrophotometer.

Application of enamel conditioner rinse solution (15 ml) for 30 seconds.

Application of 10 sprayshots (1.5 ml) of experiment bleaching solution (18% H 2 O 2 ) and hold for 1 minute.

Rinse with water for 30 seconds.

Repeat the enamel conditioner rinse solution and the application of bleach for 2 more times.

Application of enamel remineralizer rinse (15 ml) for 30 seconds

Colour measurement re-evaluation.

Group HW-35:

Initial colour measurement using Spectrophotometer.

Application of enamel conditioner rinse solution (15 ml) for 30 seconds.

Application of 10 spray shots(1.5 ml) of experiment bleaching solution (35% v/v H 2 0 2 ) and hold for 1 minute.

Rinse with water 30 seconds.

Repeat the enamel conditioner rinse solution and the application of bleach for 2 more times.

Application of enamel remineralizer rinse (15 ml) for 30 seconds Colour measurement re-evaluation.

Group OP:

Application of commercial bleaching gel (Opalescent) for 1 hours.

Rinse with water.

Colour measurement re-evaluation.

Figure 15 shows the average visual score difference and the mean (SD) tooth colour difference. According to these results, bleaching with 35% v/v hydrogen peroxide achieves a better score difference and tooth colour change after a bleaching period of 5 days.

EXAMPLE 4

This study evaluates the morphologic and chemical changes of enamel surface after treatment with the bleaching product of the invention

Materials and Methods

1. Colour Analysis

Specimen Preparation

Extracted human anterior teeth (n=15) are used in this study. From the time of extraction, these teeth are kept hydrated in distilled water at room temperature. Teeth are randomly divided into three groups and are treated as follows.

Group L Group Gel-X Group Gel-G

- Apply HW Primer for 30 seconds

- Rinse with water for 10 seconds

- Apply 35% v/v hydrogen peroxide solution (Lot#G0128003) for 30 seconds

- Rinse with water for 10 seconds

- Repeat the bleaching process for two more times

- Apply HW Remineralizer

(Lot#0ADCZET00002) for 30 seconds - Colour analysis

Group Gel-X

- Apply HW Primer for 30 seconds

- Rinse with water for 10 seconds

- Apply HW Gel-X solution for 30 seconds

- Rinse with water for 10 seconds

- Repeat the bleaching process for two times more

- Apply HW Remineralizer (Lot#0ADCZET00002)

for 30 seconds

- Colour analysis

Group Gel-G

- Apply HW Primer for 30 seconds

- Rinse with water for 10 seconds

- Apply HW Gel-G solution for 30 seconds

- Rinse with water for 10 seconds

- Repeat the bleaching process for two times more

- Apply HW Remineralizer (Lot#0ADCZET00002) for 30 seconds

- Colour analysis

For each of the test groups, the colour difference (ΔΕ) is measured with a spectrophotometer (Crystaleye; Olympus America Corp., Center valley, PA) from 5 teeth for each variable combination tested. According to the manufacturer's information, this spectrophotometer measures the reflectance or transmittance factors of an object one wavelength at a time. This computer-aided tooth colour determination used 7 LEDs (light-emitting diodes) as an illumination source with 45/0-degree geometry. At the beginning of each session and prior to data acquisition, the instrument is calibrated using a calibration plate according to the manufacturer's recommendation. A plastic protective cap, which is acted as an aperture is placed on the spectrophotometer head and then the spectrophotometer is positioned to capture the crown image. The capture time is 0.2 seconds. The spectral data from the tooth is acquired from the captured image of the tooth. The reflectance values, from 400 to 700 nm, with 1-nm intervals for each pixel, are transferred from the spectrophotometer to a computer. The spectral data of the bleach tooth are analyzed and compared to the control tooth using ΔΕ to determine the colour difference in the body area (3.0 x 3.0 mm) of the crown. Determination of ΔΕ is based on the following equations:

ΔΕ = {(AL*) 2 + (Aa*) 2 + (Ab* } i/ 2

Where AL*=L*experimental tooth - L*control tooth, Aa*=a*experimental tooth - a* control tooth,

Ab* = b* experimental tooth - b* control tooth

Colour data of the control tooth images and the experimental tooth images are recorded. The mean and standard deviation of ΔΕ values are calculated.

2. EDX and SEM Analysis

Specimen Preparation

Extracted human third molars (n=3) are selected based on the criteria that there is no evidence of caries, no restorations, and they lack any cracks or fractures in the crown. Overall, the tooth size is within a 10% standard deviation. From the time of extraction, these teeth are kept hydrated in distilled water at room temperature. The coronal parts of each tooth are sectioned and enamel surfaces are cleaned and polished using water and fluoride-free pumice (3M ESPE, St. Paul, MN) with prophylaxis brush at a slow speed. Subsequently, specimens are cleaned in water and air dried. Using double-sided diamond disks (Brasseller USA, Savannah, GA), each tooth is cut incisocervically (vertically) into two parts. While one parts received no bleaching agent (control), the other parts are subjected to bleaching products. The bleaching protocol is shown in Table 1. All the experimental specimens are stored in water for 24 hours after the treatment.

EDX Analysis

To determine the element present on the enamel surface with or without the treatment, an energy dispersive x-ray spectroscopy (EDS) (FEI Sirion SEM, NPGS v.9, EDAX Falcon, Mahwah, NJ) are performed on a separate set of teeth. In each measurement area, the intensity profile of the major elements present is analyzed. The accelerating voltage is set at 15 KV with a working distance of 15 mm. The x-ray detector is set at 5 cm throughout the experiment under secondary electron (SE) mode at a magnification XI 000. Concentrations are determined after calculating the average percentage of the weight of a particular element at each spot.

Element content in %wt of calcium (Ca), phosphorus (P) and oxygen (O) are measured as a relative amount of the total element.

SEM Analysis

Specimens are analyzed using scanning electron microscope (SEM) (FEI Sirion SEM,

Mahwah, NJ) and the morphology of the enamel surface is observed.

Results

1. Colour Analysis

The mean and standard deviation of ΔΕ values are as followed: group L (1.52 ± 0.86), group Gel-X (0.96 ± 0.41), group Gel-G (0.80 ± 0.54). The greatest ΔΕ values qre obtained from the group L, however there is no significant different among these three testing groups (P =0.206).

Figure 16: Representative photograph of colour data gathered by spectrophotometer (a) group L, (b) group Gel-X and (c) group Gel-G. Note that each picture illustrates the different colour between the experimental bleached tooth (left) and the non bleached tooth (right).

2. EDX and SEM Analysis

The EDX analyses regarding the elemental composition (Ca, O, P) that are recorded in % by weight on the enamel surface are presented in Figure 17. The data reveal no significant changes in P %wt in all groups. The Ca %wt in group L decreases in bleached specimen, while it increases in group Gel-X and group Gel-G.

Figure 17: EDX analysis.

A Comparison between SEM images of bleached and remineralized enamel vs. untreated enamel reveals no alteration in surface enamel morphology in most cases. Where differences appear, the bleached enamel is either smoother or more porous than the control with no favoured trend. Only in group Gel-X some remaining of remineralizer solution is found deposited on the enamel surface.

Figure 18 shows representative SEM micrographs of enamel surface in group L (a) non bleached or control and (b) bleached part of the same tooth (original magnification xlOOO).

Figure 19 shows representative SEM micrographs of enamel surface in group Gel-X (a) non bleached or control and (b) bleached part of the same tooth (original magnification xlOOO). Notice: there is some remaining remineralizer deposited on the enamel surface. Figure 20 shows representative SEM micrographs of enamel surface in group Gel-G (a) non bleached or control and (b) bleached part of the same tooth (original magnification xlOOO).

EXAMPLE 5

The aim of this study is to evaluate the colour change of teeth exposed to different bleaching time. Extracted molar teeth (n=5 per group) are treated as follows:

- Group Without Enamel Conditioner Rinse (Control)

Initial colour measurement using Spectrophotometer.

Application of 10 spray shots (1.5 ml) of bleaching Solution 2 (35% v/v H 2 0 2 ) and hold for 1 minute.

Rinse with water 30 seconds.

Repeat the application of bleach for 2 more times.

Colour measurement re-evaluation.

- Group With Low-pH (pH=5) Enamel Conditioner Rinse (Test)

Initial colour measurement using Spectrophotometer.

Application of enamel conditioner rinse solution (15 ml) for 30 seconds.

Application of 10 sprayshots (1.5 ml) of bleaching Solution 2 (35% v/v H 2 0 2 ) and hold for 1 minute.

Rinse with water 30 seconds.

Repeat the enamel conditioner rinse solution and the application of bleach for 2 more times.

Colour measurement re-evaluation.

Figure 21 shows the results in terms of average visual score difference and of mean (SD) tooth colour difference (ΔΕ).

According to these results, applying an enamel conditioner rinse solution (pH =5) prior to bleaching with 35% v/v hydrogen peroxide reveals no significant difference in a visual score difference and tooth colour change after the bleaching periods of 3 days. EXAMPLE 6

Colour Changes of Teeth Exposed to Different Bleaching Time

Extracted molar tooth (n=5 per group) are treated as follows.

- Group 15S Initial colour measurement using Spectrophotometer.

Application of enamel conditioner rinse solution (15 ml) for 30 seconds.

Application of 10 spray shots (1.5 ml) of Bleaching Solution 2 (35% v/v H 2 0 2 ) and hold for 15 seconds.

Rinse with water 30 seconds.

Repeat the application of bleach for 2 more times.

Colour measurement re-evaluation.

- Group 30S

Initial colour measurement using Spectrophotometer.

Application of enamel conditioner rinse solution (15 ml) for 30 seconds.

Application of 10 spray shots (1.5 ml) of Bleaching Solution 2 (35%> v/v H 2 0 2 ) and hold for 30 seconds.

Rinse with water for 30 seconds.

Repeat the enamel conditioner rinse solution and the application of bleach for 2 more times.

Colour measurement re-evaluation.

Figure 22 shows the results in terms of average visual score difference and of mean (SD) tooth colour difference (ΔΕ).

According to these results, bleaching with 35 > v/v hydrogen peroxide for 60 seconds is the most effective in bleaching teeth as it reveals higher difference in a visual score difference and tooth colour change.

EXAMPLE 7

Colour Changes of Anterior Teeth Exposed to Bleaching.

Methods and materials.

Extracted mandibular central incisor (n=5 per group) and maxillary canine are treated as follows: Initial colour measurement using Spectrophotometer Application of enamel conditioner rinse solution (15 ml) for 30 seconds.

Application of 10 spray shots (1.5 ml) of bleaching Solution 2 (35% v/v H 2 0 2 ) and hold for 60 seconds.

Rinse with water for 30 seconds.

Repeat the enamel conditioner rinse solution and the application of bleach for 2 more times.

Colour measurement re-evaluation.

Figure 23 shows the results in terms of average visual score difference and of mean (SD) tooth colour difference (ΔΕ).

According to these results, bleaching on posterior teeth reveals a higher score in a visual score difference and tooth colour change.

EXAMPLE 8

Evaluation of colour changes induced by a new system of professional home bleaching The study aims to evaluate changes in the colour of teeth by using the whitening system of the invention. After one week (Tl) and after two weeks of use (T2). 36 subjects aged between 18 and 50 years are chosen, PSR 1-2, that have had no tooth whitening in the previous 24 months. Exclusion criteria for the individuals are numerous: cuts, sores, lesions and wounds of the mucous membranes, hypersensitivity to hydrogen peroxide, wearers of fixed orthodontic appliances and subjects, bearers of crowns, veneers or bridges on the upper teeth, teeth by conservative restorations 13 to 23, smoking over 10 cigarettes a day, carious lesions present, the presence of tartar on the second sextant developing enamel and dentine abnormalities. All subjects are asked to brush their teeth without toothpaste and then immediately, the colour (TO) of teeth 2.1 and 2.2 is measured using a spectro-photometer (SpectroShade Micro ®). The subjects are asked to use the bleaching kit at home and told to follow an appropriate oral hygiene procedure (not to take substances that can cause the formation of pigments for at least an hour before and one hour after rinsing). After a week of using the kit for whitening teeth (Tl), the colour of 2.1 and 2.2 of all subjects is measured. After the first week, each of the participants is asked if he/she wishes to continue with the use of the whitener for another week. The first 18 volunteers were asked to continue to use the whitening system. After an additional week, the colour of 2.1 and 2.2 (T2) is measured on the remaining members of the group. The results reveal significant variations in the chroma of 2.1. After the first week (-0.9, p <0.0001) after the second week (- 1.04, P <0.0034). Similarly for the shade, after the first week(-1.91, p <0.0001) and after the second week (-2.24, p <0.0011). Similar results are obtained on the 2.2 on the chroma, after the first (-1.09, p <0.0001) and the second week (- 1.13, P <0.0013), and on the shade after the first ( -3.02, P <0.0001) and the second week (-1.92, p <0.0001). The spectrophotometric analysis is used to define an indicator (ΔΕ), which shows how much the selected image is close to the readings of the tooth, based on an arithmetic average of value, chroma and shade. If ΔΕ exceeds two, it means the difference between the appearance of the tooth can be easily perceived by the human eye, and there is a visible colour change. In this sample, the ΔΕ after a week of treatment is found to be 2.44, but after two weeks of treatment 3.04. These results are true for both the 2.1 and the 2.2, except for slight variations. The new system of teeth whitening is proved to be effective in positively changing the colour of the tooth.

EXAMPLE 9

Evaluation of pH induced by the use of a new system of professional home bleaching The study aims to assess the changes in pH in the oral cavity caused by the use of the whitening system of the invention for the whole procedure. 18 subjects aged between 18 and 50 years are chosen. The analysis of salivary pH is performed with a pH meter (pH-day 2 ®, Menfis bioMedica). The process of using the new whitening product is as follows: a primer for 30 seconds, spray with hydrogen peroxide, primer for 30 seconds, spray with hydrogen peroxide and remineralizer for 60 seconds after the spray rinse for 60 seconds and after rinse with water. After measuring the pH of saliva, the active tip of the probe of the meter is positioned at the level of the vestibular surface of one of the upper incisors for 10 seconds to record the pH of the enamel. The probe is then placed in the upper fornix and held in position using an elastic orthodontic separator positioned between the upper molars. The thin and flexible probe cable is passed under the elastic separator and out of the corner of the mouth so as not to interfere with the closure and allow the patient to rinse and also to enable the application of the product according to the experimental procedure. This allows the pH of the upper vestibule to be continuously monitored throughout the duration of the test, after which the active tip of the probe was moved from the fornix and repositioned on the vestibular surface of the upper incisor for 10 seconds to measure the pH of the enamel at the end of experimental procedure. The subjects, during the recording of pH, can close their mouths, swallow and rinse according to the experimental procedure without inhibiting salivary clearance. The results show that the pH of the enamel is essentially unchanged from the beginning (6.59, sd 0.22) at the end of the procedure (6.88 sd 0.24). To illustrate more clearly alterations in pH, during the bleaching procedure, it is preferable to use a line graph in which the standard deviation is contained within the limits (minimum 0.24, maximum 0.46) (Figure 24).

The procedure therefore maintains the pH of saliva at values above 5 and for short periods of less than 3 minutes a the end the pH increases (0.53) above the base value. It can be claimed that the use of this new whitening system does not alter pH significantly enough to damage gums and mucous membranes. EXAMPLE 10

Evaluating the degree of satisfaction obtained by the use of a new system of professional home bleaching

The study aims to evaluate the satisfaction of the system obtained by the use of Healthy White / Pro. The experimental group consists of 95 subject whose ages ranged from 18 to 50. All subjects were given a measurement grid from 1 to 10 (1 = none; 10 = highest), on which they are to express their satisfaction with regard to taste, convenience, and the result obtained by the system of colour bleaching. Any judgement above 6 or above half the scale was considered positive. According to the table (Figure 25) 94% of the subjects gave a positive response regarding the practicality of the product. 87% of subjects where satisfied with the colour obtained and 55% of these were completely satisfied (rating 8- 10). With regard to the taste 11% gave a negative judgement. The results therefore demonstrate a high degree of satisfaction with this new whitening system.