WO2012128629A1

WO2012128629A1 - Cleaning composition for dental objects, kit and method

Info

Publication number: WO2012128629A1
Application number: PCT/NL2012/050178
Authority: WO
Inventors: Frederik BATEMA
Original assignee: Simus B.V.
Priority date: 2011-03-23
Filing date: 2012-03-22
Publication date: 2012-09-27
Also published as: NL2006460C2; EP2689002A1

Abstract

The invention provides a cleaning composition for cleaning dental objects such as dentures dental braces and/or dentist's tools, comprising lactic acid. The denture cleaning liquids described here were found to provide an improved cleaning effect, which allows for a shorter cleaning time. The cleaning composition is effective against various types of contamination, including smoking and coffee stains, micro-organisms and tartar. The invention also provides a kit and a method for cleaning dental objects.

Description

Cleaning composition for dental objects, kit and method

FIELD OF THE INVENTION

The invention relates to a cleaning composition, a kit and a method of cleaning.

BACKGROUND OF THE INVENTION

Dentures used by a person attract contamination, such as micro-organisms, tartar, and stains caused by smoking or beverages such as coffee. In the manufacture of dentures, traces of cement and gypsum from the moulds may still remain. Thus, dentures need to be cleaned regularly. Commercially available denture cleaners include tablets and powders that are dissolved in water for cleaning the dentures.

OBJECT AND SUMMARY OF THE INVENTION

The invention provides a cleaning composition for cleaning dental objects such as dentures dental braces and/or dentist's tools, comprising lactic acid, preferably at least 6% w/w lactic acid, more preferably at least 8%. Liquid dental cleaners are preferred over tablets and powders, as they are more convenient to apply. The denture cleaning liquids described here were found to provide an improved cleaning effect, which allows for a shorter cleaning time for a similar cleaning result. Preferably, the composition is based on an aqueous solution of lactic acid. Natural lactic acid (L-Lactic acid) is preferred, although D-lactic acid or a mixture of D and L stereoisomers could also be used. The cleaning composition showed to be highly versatile in its uses, and is effective against various types of contamination, including smoking and coffee stains, microorganisms and tartar. In addition to dentures, the cleaning composition is also suitable for the cleaning of other dent-related items, such as dentist's tools or dental braces. Apart for private use, the relatively short cleaning time makes the cleaning liquid suitable for use in professional denture laboratories were often fast cleaning is desired, for instance for removing debris and waste material produced when preparing or adjusting dentures, in particular traces of cement and gypsum.

In addition to lactic acid, the composition may comprise other functional ingredients. The constitution of the compositions may range from a clear solution to a relatively thick paste. The composition may be a multi-phase system such as an emulsion or dispersion. The cleaning composition may be a concentrated liquid, for instance having 20, 30 or 40% lactic acid w/w. One part of such a concentrated solution may be diluted with 1 -20 parts of water to obtain a lactic acid concentration ready to use.

The palatability of lactic acid solutions, even at relatively high concentrations was acceptable; thus rinsing off remainders of the denture cleaning liquid after cleaning did not have to be as thorough as for more foul tasting cleaning agents. It is preferred if the liquid comprises from 6-15% w/w lactic acid, more preferably from 6-12% w/w lactic acid. Optimal cleaning results are obtained if the liquid is an aqueous composition having a pH below 3.5.

The compositions described herein are particularly suitable for cleaning dentures using mechanical cleaning, for instance using an electrical tooth brush or a sonic tooth brush. Apart from cleaning bacteria and food remains, the lactic acid makes the compositions are also particularly suitable to remove traces of gypsum, cement and adhesives from dentures. Such materials may remain on dentures as a result of the production or repair methods of dentures in moulds. In a preferred embodiment, the composition comprises a combination of lactic acid and an oxidant. The combination of lactic acid and an oxidant showed an improved cleaning effect and also shortens the cleaning time to minutes rather than hours.

Preferably, the composition comprises a source of peroxide radicals. Peroxide radicals showed to give a good cleaning effect combined with lactic acid. The oxidizing properties of peroxides also may give a bleaching effect. The combination of lactic acid and peroxide radicals showed to give relatively stable solutions. Possible sources of peroxides comprise enzymatic systems (peroxidases), including lactoperoxidase, horseradish peroxidase and glucoperoxidase systems. Other sources of peroxide radicals are organic and inorganic peroxides. Numerous peroxide compounds are commercially available, although some may be unsuitable for use in a denture cleaning composition due to the toxicity that some compounds may have at the preferred concentration. Suitable organic peroxides include peroxy acids (derived from carboxylic acids) and organic hydroperoxides (derived from ethers or alcohols) include peracetic acid, perpropionic acid, perbutyric acid, peroctanoic acid, perglycolic acid, perglutaric acid, persuccinic acid, perlactic acid, percitric acid, perdecanoic acid or mixtures thereof. A particularly suitable compound for cleaning dentures is carbamide peroxide. Suitable inorganic peroxides include the peroxy salts of alkali metals and earth alkali metals with a relatively low toxicity, such as lithium peroxide, sodium peroxide, potassium peroxide, magnesium peroxide and calcium peroxide. Hydrogen peroxide is most preferred as a source of peroxide radicals. Hydrogen peroxide has a low toxicity, reacts to yield water and is well soluble in aqueous solutions. Also, a synergistic effect is observed when cleaning dentures or other dental objects with a combination of hydrogen peroxide and lactic acid. Also, lactic acid stabilises the peroxide during storage. Part of the lactic acid may react with hydrogen peroxide to yield perlactic acid. Hydrogen peroxide also ensures a better cleaning result may be obtained in a shorter time.

In a preferred embodiment, the cleaning composition comprises hydrogen peroxide in an amount of at least 0.05% w/w, or a molecular equivalent amount of peroxide. In such amounts, an advantageous cleaning effect and increase in cleaning speed is observed, and is particularly successful in removing stains. Preferably, the denture cleaning composition has from 0.05-5% w/w hydrogen peroxide, or a molecular equivalent amount of peroxide. In yet another embodiment, the composition also comprises at least 1 %, preferably at least 6% w/w ethanol. Compositions using ethanol combined with lactic acid show an improved synergistic cleaning effect. Relatively high ethanol concentrations having at least 4% w/w ethanol, give a significant antibacterial effect. Preferred concentrations are the range of 6- 12% w/w ethanol.

In a preferred embodiment the composition comprises at least 6% lactic acid, at least 1 % ethanol, and at least 0.05% w/w hydrogen peroxide. The combination of these three ingredients shows a very good cleaning effect. It is advantageous if the composition comprises at least one acid-resistant gel forming agent. The gel forming agent allows to obtain an improved cleaning effect and efficient and convenient use, as the liquid may be kept on the area to be cleaned for a longer time due to the viscosity and/or adhesive effect of the gel. However, is was discovered that not all gel-formers were compatible with lactic acid. The viscosity may range from a slightly viscous liquid to a slowly flowing gel composition. Preferably, the gel forming agent comprises at least one compound selected from the group consisting of gellan gum, carrageenan gum and xanthan gum, or a mixture thereof. Xanthan gum showed the best results. Gel forming agents are typically added in amounts of 0.01 -10%, depending on the viscosity desired. Compositions in the range of 0.05-3% w/w, gellan gum (or an equivalent of other thickeners are preferred, giving a good balance between the ease of application and spreading the

Preferably, the composition also comprises at least one acid resistant flavour compound comprising extracts from mint and/or eucalyptus, preferably comprising menthol. These flavour compounds showed to be particularly suitable to mask the taste of lactic acid. Flavours may include mint extracts, in particular extracts obtained from peppermint, spearmint, and apple mint. Fruity tastes such as strawberry, orange and cola may also be used. Also, synthetic equivalents may be used. The flavour gives a pleasant taste for the user of the cleaned denture. Multiple flavours may be mixed. Flavour compounds comprising menthol are preferred, as it is stable in the presence of lactic acid and hydrogen peroxide. Also, menthol proved to be particularly effective in the masking of the taste of lactic acid.

The invention may further comprise additional ingredients. The addition of surfactants may be desirable in some cases, in order to obtain a homogenous composition.

The invention further provides the use of a cleaning composition according to any of the preceding claims for the cleaning dental objects, in particular dentures, dental braces and/or dentist's tools.

The invention further provides a kit for cleaning dentures, comprising at least one container comprising the denture cleaning liquid as described herein, a receptacle for immersing dentures in the cleaning composition, and at least one mechanical cleaning device. Such a kit makes it relatively easy to clean dentures by pouring the liquid into the container, and cleaning the dentures using the mechanical cleaning device (for instance a brush), The container with denture cleaning liquid may actually be a sealed as the receptacle for immersing dentures, in which case the receptacle is immediately ready to use after opening. The invention further provides a method for the cleaning of dentures, comprising the steps of providing dentures to be cleaned, providing a denture cleaning liquid as described herein, contacting the dentures with the cleaning composition for a predetermined cleaning time, optionally combined with mechanical cleaning of the dentures. The compositions described herein are particularly suitable for cleaning dentures using an electrical tooth brush. In a preferred embodiment, the contacting of the dentures with the cleaning composition is combined with ultrasonic treatment. The combination of ultrasonic waves and the denture cleaning composition gives a good cleaning result in a relatively short time. The ultrasonic waves may be generated by commercially available ultrasonic equipment, in particular ultrasonic baths. This is of particular interest for professional denture laboratories.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a kit of parts according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Compositions

A number of example formulations of the cleaning compositions according to the invention were prepared, as shown in table I. These compositions are particularly useful for daily home cleaning of dentures, but may also be used for other dent-related objects such as dental braces or dentist's tools. A typical treatment time of 2-10 minutes of immersion of the object to be cleaned, optionally combined with mechanical of ultrasonic cleaning, is sufficient for a satisfactory cleaning result. Optionally, surfactants and other functional ingredients could be added to the composition to stabilize the composition and to further improve the cleaning result.

Table I: Denture cleaning compositions

Formula %w/w A B C D

lactic acid 1 1 1 1 1 1 1 1

HOOH - 1 - 1

ethanol - - 10 10

menthol 0.1 0.1 0.1 0.1

water To 100% To 100% To 100% To 100% pH 1 .9 1 .9 1.9 1 .9 The ingredients were mixed and put in bottles using standard techniques. The cleaning compositions were tested on dentures, pre-treated with representative microorganisms typically found on dentures, without additional mechanical cleaning such as brushing. After 5 minutes of immersion of the dentures in the formulas mentioned above, the microorganisms on the dentures were quantified. Relative test results are given in table II. The lactic acid formulations according to the invention all proved to give satisfactory cleaning of dentures. Most notably, the combination of lactic acid and an oxidant (hydrogen peroxide in this example), showed a synergistic disinfecting effect. The addition of alcohol also improved the disinfecting effect. Menthol was used as the flavouring agent in this example, and was noted to be effective in covering the taste of lactic acid, improving the palatability of traces of the cleaning composition that may be left in the denture even after washing the denture with water. Combining the cleaning with mechanical cleaning using a regular tooth brush improved the cleaning result, but the relative cleaning effect for the formulas appeared to be the same.

Table II: Relative test results of denture cleaning compositions after 8 hours

Formula A B C D

Cleaning effect + +++ ++ ++++

The cleaning was also repeated using the cleaning compositions mentioned above during 5 minutes while exposed to ultrasonic waves in a commercially available ultrasonic bath. The relative cleaning results of the different compositions remained mostly the same, but the ultrasonic treatment appeared to give a further enhancement, in particular in the compositions B and D comprising the oxidant hydrogen peroxide. This indicates that a further synergistic effect in using the lactic acid compositions with an oxidant combined with ultrasonic treatment, and also significantly decreases the cleaning time needed. This is of particular importance for denture professionals concerned with the manufacture, customizing and repair of dentures, who also regularly need to clean dentures as part of their work. Concentrated formulations

The invention also provides concentrated denture cleaning compositions shown in table III. In principle, all of the cleaning compositions A, B, C and D mentioned in Table I could also be prepared as a concentrated composition, wherein only water needs to be added to arrive at the concentrations. A preferred concentrated cleaning solution would be in the range of 1 -1 Ox concentrated. Table III: concentrated denture cleaning compositions

Formula %w/w E (x2) F(x4)

lactic acid 20 40

HOOH 4

ethanol

menthol 0.2 0.4

water To 100% To 100%

PH 1.5 1 .1

Formula E (2x concentrated) could for instance be diluted with an equivalent volume of water to obtain a cleaning solution having 10% lactic acid. Formula F (4x concentrated) could be diluted with 3 equivalent volumes of water to yield a cleaning solution comprising 10% lactic acid and 1 % hydrogen peroxide.

The concentrated cleaning compositions could also be used as such, without diluting, to obtain a more thorough and/or faster cleaning result. Highly concentrated compositions may be regarded as irritating chemicals, and as such use is only recommended for trained professionals.

Gel cleaner

Gel cleaners have the advantage to remain attached to the denture after the denture cleaner has been spread out over the surface of the cleaner. Various acid-resistant thickeners may be used as an addition to the formulations mentioned above. Suitable thickeners include carbomers and galactomannans, including gellan gum, carrageenan gum and xanthan gum. Gellan gum showed a particularly good adhesive effect to dentures, and also proved to have a good resistance to the presence of oxidative species such as HOOH. An example of a liquid gel formulation for denture cleaning is shown below in table IV. Gellan gum concentrations give a notable adhesive effect from around 0.01 % w/w, but the best results are obtained when concentrations in the range from 0.1 -3%w/w are used. The gel formulations may for instance be packed in a squeeze bottle, pump bottle or tube. Table IV: gel denture cleaning compositions

Formula %w/w G H

lactic acid δ 8

HOOH 1 xanthan gum 1 1

menthol 0.1 0.1

water To 100% To 100% pH 2 2

Viscosity

Cleaning kit

Although the cleaning compositions described herein could be sold separately, a denture cleaning kit provides an attractive package for cleaning dentures, suitable for consumers as well as professionals. The proposed cleaning kit comprises at least one container comprising a cleaning composition according to the invention, such as a plastic, glass bottle or, for gel formulations a tube or pump bottle. The amount of liquid should be available in a quantity sufficient for one or more cleanings. Typically 10-200 ml denture cleaning composition per cleaning is sufficient, depending on the

concentration. The container could also comprise a concentrated cleaning solution that is to be diluted with water to obtain the predetermined concentrations for use.

In addition to the cleaning liquid, the kit also comprises a receptacle of sufficient size and shape to hold a denture immersed in the cleaning liquid. The receptacle could for instance be have a box-like shape, optionally provided with a lid, but may also be a sealable bag.

Further, the kit comprises one ore more mechanical tools for additional cleaning of the dentures. Such tools could for instance comprise a brush, toothpicks and the like. Mechanical cleaning of dentures before or during immersion of the dentures into the cleaning liquid improves the cleaning result.

Alternatively, the cleaning kit may also be made suitable for the cleaning of other objects, such as dental braces or dentist's tools, or tools used in the manufacture of dentures.

Figure 1 shows an example of a cleaning kit 1 for dentures (dentures not shown). The kit includes a bottle 2 of concentrated denture cleaning liquid as described herein, a resealable receptacle 3 provided with a removable holder 4, shaped to accommodate dentures, and a tooth brush 5. The user may put the concentrated denture cleaning liquid 2 in the receptacle 3 up to a first level indicator A, and then dilute with water up to a second level indicator B to obtain the desired dilution. Dentures may be placed in the denture holder 4, the dentures may be immersed into the diluted cleaning liquid, for instance for 5 minutes. The cleaning liquid will spread into the holder 4 through apertures 6 provided in the bottom thereof. During cleaning or storage, the lid 7 of the receptacle 3 may be sealed liquid-tight. The cleaning may be enhanced by using the brush 5, which is a hand brush in this case but could also be a disposable brush top for use in aa mechanical or ultrasonic electrical tooth brush. After cleaning, the cleaning liquid may be rinsed off the cleaned dentures using water, and the cleaning liquid may be disposed. Similar kits may be provided for dental braces or dentist's tools, wherein the shape of the receptacle 2 may be modified to accommodate the object to be cleaned.

Claims

Claims:

1. Cleaning composition for cleaning dental objects such as dentures, dental braces and/or dentist's tools, comprising lactic acid.

2. Cleaning composition according to claim 1 , wherein the composition comprises at least 6% w/w lactic acid, more preferably at least 8%.

3. Cleaning composition according to claim 1 or 2, wherein the composition comprises a combination of lactic acid and at least one oxidant.

4. Cleaning composition according to claim 3, wherein the composition comprises a source of peroxide radicals.

5. Cleaning composition according to claim 3 or 4, wherein the composition comprises hydrogen peroxide.

6. Cleaning composition according to any of the claims 4 or 5, wherein the composition comprises at least 0.05% w/w hydrogen peroxide, or a molecular equivalent amount of peroxide.

7. Cleaning composition according to any of the preceding claims, wherein the composition also comprises at least 1 % w/w ethanol, preferably at least 6% w/w ethanol.

8. Cleaning composition according to any of the preceding claims, wherein the composition comprises at least 6% lactic acid, at least 1 % w/w ethanol, and at least 0.05% w/w hydrogen peroxide.

9. Cleaning composition according to any of the preceding claims, wherein the composition comprises at least one acid-resistant gel forming agent.

10. Cleaning composition according to claim 10, wherein the gel forming agent comprises at least one compound selected from the group consisting of gellan gum, carrageenan gum and xanthan gum, or a mixture thereof.

1 1 . Cleaning composition according to any of the preceding claims, wherein the composition also comprises at least one acid resistant flavour compound comprising mint and/or eucalyptus, preferably comprising menthol.

5 12. Use of a cleaning composition according to any of the preceding claims for the cleaning dental objects, in particular dentures, dental braces and/or dentist's tools.

13. Kit for cleaning dental objects such as dentures, dental braces and/or dentist's tools, comprising at least one container comprising the cleaning composition according to any0 of the preceding claims 1 -1 1 , a receptacle for immersing the dental object to be cleaned in the cleaning composition, and optionally at least one mechanical cleaning device.

14. Method for the cleaning of dentures or other dental objects, comprising the steps of

- providing dentures to be cleaned,

5 - providing a cleaning composition according to any of the claims 1 -1 1 , and

- contacting the dentures with the cleaning composition for a predetermined cleaning time, optionally combined with mechanical cleaning of the dentures.

15. Method according to claim 14, wherein the contacting of the dentures with the o cleaning composition is combined with ultrasonic treatment.