JP7719600B2 - Denture cleanser composition - Google Patents

Description

The present invention relates to a denture cleanser composition. More specifically, the present invention relates to a liquid cleanser composition, especially a concentrated liquid cleanser composition.

In recent years, concentrated liquid denture cleansers that eliminate the need for dissolving in water have been proposed as denture cleansers that can be used in a short amount of time. However, the types of dirt that adhere to dentures include denture plaque, food residue, stains (colored deposits), and tartar, and these must be cleaned and removed effectively in a short amount of time. Stain adhesion to dentures is particularly undesirable from both a hygienic and aesthetic standpoint, making stain removal a major challenge for denture cleansers.

For this reason, various liquid denture cleansers have been proposed that are effective in disinfecting Candida and removing stains. For example, a concentrated liquid denture cleanser composition containing a combination of (A) hydroxyethanediphosphonic acid, (B) an alkylamine oxide, and (C) benzoic acid or a derivative thereof (see Patent Document 1), and a liquid denture cleanser composition containing (A) hydroxyethanediphosphonic acid and (B) one or more surfactants selected from anionic surfactants and amphoteric surfactants, and having a pH of 5 to 9 at 20°C (see Patent Document 2) have been proposed. These compositions are said to be able to effectively remove stains without containing peroxides or bleaching agents.

JP 2018-90501 A JP 2018-90499 A

The object of the present invention is to provide a denture cleanser composition that has a disinfecting effect against Candida and also inhibits stain adhesion (discoloration) to dentures.

In the course of conducting research to achieve the above-mentioned objective, the inventors discovered that dentures cleaned with a denture cleanser containing a cationic surfactant that exhibits excellent antibacterial properties against Candida bacteria are prone to stain buildup over time, resulting in staining. Through extensive research to resolve this issue, they discovered that the use of cationic surfactants, specifically compounds in which a nitrogen atom is bonded to a linear carbon chain having 6 to 18 carbon atoms, and particularly quaternary ammonium salts, significantly reduces stain buildup on dentures and prevents denture discoloration.

The present invention was completed after further investigation based on the discovery of the problems caused by the cationic surfactants and the means to solve them, and includes the following embodiments.

(I) Denture cleanser composition (I-1) A denture cleanser composition containing, as a cationic surfactant, a compound in which a group having an open carbon chain of 6 to 18 carbon atoms is bonded to one nitrogen atom.
(I-2) The denture cleanser composition according to (I-1), wherein the compound is a quaternary ammonium salt.
(I-3) A denture cleanser composition according to (I-1) or (I-2), which is a liquid composition, preferably a concentrated liquid composition.

(II) Method for Using a Cationic Surfactant (II-1) A method for using a cationic surfactant, characterized in that a compound having a group having an open carbon chain of 6 to 18 carbon atoms bonded to a nitrogen atom is blended into a denture cleanser composition as a cationic surfactant, thereby imparting to the denture cleanser composition a disinfecting function and a function for inhibiting stain adhesion to dentures.
(II-2) The method of use according to (II-1), wherein the compound is a quaternary ammonium salt.
(II-3) The method of use according to (II-1) or (II-2), wherein the denture cleanser composition is a liquid composition, preferably a concentrated liquid composition.

The present invention provides a liquid denture cleanser composition that not only has a disinfecting effect on dentures but also inhibits stain deposition. Specifically, the denture cleanser composition of the present invention exhibits excellent disinfecting effect against Candida due to the disinfecting action of the cationic surfactant, while simultaneously inhibiting stain deposition on dentures caused by the cationic surfactant. Therefore, the present invention effectively prevents discoloration of dentures due to stain deposition when using a liquid denture cleanser, which is a problem with liquid denture cleanser compositions containing cationic surfactants. Furthermore, because the denture cleanser composition of the present invention can be provided in liquid form, there is no need to go through the trouble of dissolving solid agents such as tablets or granules, and it can be used immediately to clean dentures either as is or after simple steps such as dilution.

(I) Denture cleanser composition The denture cleanser composition of the present invention is characterized by containing, as a cationic surfactant, a compound in which a group having an open carbon chain of 6 to 18 carbon atoms is bonded to a nitrogen atom (hereinafter, this will be referred to as "the compound").

Specific examples of the open-chain carbon chain having 6 to 18 carbon atoms (hereinafter simply referred to as "C6-18 open-chain carbon chain") in this compound include open-chain hydrocarbon groups (acyclic hydrocarbon groups). Such open-chain hydrocarbon groups include open-chain saturated hydrocarbon groups (alkyl groups) and open-chain unsaturated hydrocarbon groups (alkenyl groups, alkynyl groups). Open-chain saturated hydrocarbon groups are preferred. The open-chain saturated hydrocarbon group may be either a linear alkyl group or a branched alkyl group, but is preferably a linear alkyl group.

The number of carbon atoms in the open carbon chain can be selected from the aforementioned range of 6 to 18, and although not limited, is preferably 8 to 18 carbon atoms, and more preferably 12 to 18 carbon atoms. Specific examples include capryl groups (octyl groups), lauryl groups (dodecyl groups), myristyl groups (tetradecyl groups), cetyl groups (hexadecyl groups), and stearyl groups (octadecyl groups). Lauryl groups, cetyl groups, and stearyl groups are preferred, with lauryl groups being more preferred.

The group having a C6-18 open carbon chain may be the C6-18 open hydrocarbon group itself, or may be a group partially containing the C6-18 open hydrocarbon group. The group partially containing a C6-18 open hydrocarbon group is not limited, but includes groups in which a C6-18 open hydrocarbon group is bonded to an atom other than a carbon atom, such as an oxygen atom (e.g., an alkoxy group), and alkyl groups containing such alkoxy groups (alkoxyalkyl groups). Specific examples include alkoxyalkyl groups in which an alkyl group having 1 to 6 carbon atoms, preferably 2 to 3 carbon atoms, is bonded to an alkoxy group having 6 to 18 carbon atoms.

The present compound is a compound in which one group having a C6-18 open carbon chain is bonded to a nitrogen atom, and is preferably a quaternary ammonium compound. The other group bonded to the nitrogen atom is desirably an atom or group other than the group having a C6-18 open carbon chain, or an acyclic group, such as a hydrogen atom or an open-chain alkyl group having 1 to 5 carbon atoms. Preferably, it is an alkyl group such as a methyl group or an ethyl group, and more preferably a methyl group.
The present compound is preferably a trimethyl-type quaternary ammonium compound in which a group having one C6-18 linear carbon chain and three methyl groups are bonded to a nitrogen atom. Specific examples include lauryltrimethylammonium (dodecyltrimethylammonium), cetyltrimethylammonium (hexadecyltrimethylammonium), stearyltrimethylammonium (octadecyltrimethylammonium), coconut alkyltrimethylammonium, tallow alkyltrimethylammonium, octadecyloxypropyltrimethylammonium, and salts thereof. Lauryltrimethylammonium and its salts are preferred. Examples of salts include, but are not limited to, chlorides.

As demonstrated in the experimental examples described below, these cationic surfactants exhibit effective antibacterial effects against Candida fungi while being less likely to induce staining on denture materials. In contrast, dialkyl (C6-20) dimethyl ammonium salts and alkyl (C6-20) dimethyl benzyl ammonium salts, which are also quaternary ammonium compounds, exhibit effective antibacterial effects against Candida fungi, but have the disadvantage of being more likely to induce staining on denture materials. For this reason, it is preferable that the denture cleanser composition of the present invention contains only the above-mentioned compounds as cationic surfactants, either alone or in combination of two or more types, and does not contain any other cationic surfactants (for example, the above-mentioned quaternary ammonium compounds).

The amount of cationic surfactant (the present compound) in the denture cleanser composition of the present invention may be any amount sufficient to impart a disinfecting effect to the denture cleanser composition. When the denture cleanser composition of the present invention is a liquid denture cleanser composition that is used without dilution (sometimes referred to as a "concentrated liquid denture cleanser composition"), the proportion of the present compound can be appropriately selected from the range of 0.1 to 50% by mass of the total denture cleanser composition. It is preferably 0.5 to 30% by mass, and more preferably 1 to 20% by mass. When the denture cleanser composition of the present invention is a liquid denture cleanser composition that is used by diluting it with tap water (sometimes referred to as a "concentrated liquid denture cleanser composition"), for example, when the dilution rate is 10 times, the proportion of the present compound can be appropriately selected from the range of 0.01 to 5% by mass of the total denture cleanser composition. It is preferably 0.05 to 3% by mass, and more preferably 0.1 to 2% by mass.

In addition to the above components, other known ingredients can be blended into the denture cleanser composition of the present invention as needed. Examples include, but are not limited to, surfactants (anionic surfactants, amphoteric surfactants, nonionic surfactants), solvents, fragrances, colorants, buffers, pH adjusters, disinfectants, stabilizers, and rust inhibitors.

Anionic surfactants include, but are not limited to, alkyl sulfates, α-olefin sulfonates, acylamino acid salts, and alkyl phosphates. Among these, alkyl sulfates having 8 to 18 carbon atoms (e.g., lauryl sulfate), α-olefin sulfonates having 8 to 18 carbon atoms, and acylamino acid salts having an acyl group with 8 to 18 carbon atoms are preferred in terms of stain removal power, with the above-mentioned acylamino acid salts being more preferred. As salts, alkali metal salts such as sodium salts and potassium salts are preferred, with sodium salts being particularly preferred.

Examples of amphoteric surfactants include alkylamine oxides and betaine-type amphoteric surfactants. As the alkylamine oxide, alkyldimethylamine oxides, preferably those in which the alkyl group has 12 to 18 carbon atoms, and particularly 12 to 16 carbon atoms, can be used, such as lauryldimethylamine oxide.

Examples of betaine-type amphoteric surfactants include 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, fatty acid amidopropyl betaines such as coconut oil fatty acid amidopropyl betaine, and lauryl dimethylaminoacetic acid betaine. Of these, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine and fatty acid amidopropyl betaine are preferred, with fatty acid amidopropyl betaine being particularly preferred.

Preferred nonionic surfactants are polyethylene glycol-type surfactants, particularly polyoxyethylene alkyl ethers and polyoxyethylene hydrogenated castor oil. More preferred are polyoxyethylene alkyl ethers with an alkyl group containing 12 to 20 carbon atoms and an average ethylene oxide addition mole count (hereinafter abbreviated as E.O. addition mole count) of 10 to 20 moles, and/or polyoxyethylene hydrogenated castor oil with an E.O. addition mole count of 5 to 60 moles.

These surfactants can be used alone or in any combination of two or more. The amount of these surfactants (anionic surfactants, amphoteric surfactants, nonionic surfactants) in the denture cleanser composition of the present invention is not limited, but can be appropriately selected from the range of 0.1 to 50% by mass of the total amount in the case of a concentrate-type liquid denture cleanser composition, for example. It is preferably 0.5 to 30% by mass, and more preferably 1 to 20% by mass.

Water (ion-exchanged water) is usually used as the solvent, but lower alcohols such as ethanol or polyhydric alcohols such as glycerin can also be added in amounts of, for example, 1 to 30% by mass.

Since the cationic surfactants mentioned above exert a disinfecting effect, it is not necessary to include a disinfectant, but a nonionic disinfectant such as isopropylmethylphenol can also be included. In the present invention, oxidizing agents and bleaching agents such as peroxides such as sodium percarbonate and sodium perborate, hypochlorous acid or its salts, and sulfites, which are used as denture cleanser ingredients, are poorly stable, particularly in liquid compositions, and are therefore best not to include them (0% inclusion amount). Even if they are included, it is preferable to keep the amount included to a small amount of 0.03% or less, and especially 0.01% or less, of the total undiluted denture cleanser composition.

The denture cleanser composition of the present invention is preferably adjusted so that the pH at 20°C during use (when diluted with tap water) is between 5 and 9. The preferred pH is between 5.3 and 8. The pH may be adjusted spontaneously, or may be adjusted by adding a pH adjuster as appropriate.

The denture cleanser composition of the present invention is prepared in liquid form using the solvent described above. This liquid denture cleanser composition may be one that can be used as is without dilution at the time of use (undiluted liquid denture cleanser composition), but if necessary, dentures may be immersed in a diluted solution prepared by diluting a concentrated liquid denture cleanser composition with water. After immersion and cleaning, the dentures can be used by rinsing with water as necessary.
When preparing a concentrated liquid denture cleanser composition, it is preferable to design the concentration of the formulation so that when the composition is diluted with water 10 to 100 times, particularly 10 to 50 times, from the viewpoints of usability and solubility, the concentration of the cationic surfactant falls within the range of the concentration in the undiluted liquid denture cleanser composition.

The denture immersion time is preferably 5 minutes or more, more preferably 10 minutes or more. There is no particular upper limit to the immersion time, but it is usually 8 hours or less, and especially 6 hours or less. It is even more effective to immerse the denture in the liquid denture cleanser composition of the present invention after lightly removing stains with a toothbrush or the like. Furthermore, since the liquid denture cleanser composition of the present invention is liquid and highly dispersible, it may be diluted with a detergent solution and cleaned in conjunction with a known ultrasonic cleaner. In this case, the denture immersion time is preferably 15 minutes or less, and especially about 5 minutes. Using a toothbrush or ultrasonic cleaner allows for more efficient removal of denture stains.

(II) Method for Using a Cationic Surfactant The present invention provides a method for using a cationic surfactant, characterized in that a compound comprising a nitrogen atom to which one open-chain carbon chain having 6 to 18 carbon atoms is bonded is incorporated as a cationic surfactant into a denture cleanser composition, thereby imparting to the denture cleanser composition a disinfecting function and a function for inhibiting the adhesion of stains to dentures.
The type of the present compound used as the cationic surfactant and its ratio relative to the denture cleanser composition are as explained in (I) above, and the description therein can be incorporated by reference in this section.
As described above, in this specification, the terms "comprise" and "contain" encompass the meanings of "consist of" and "consist essentially of."

The present invention will be explained below using experimental examples to aid in understanding the configuration and effects of the present invention. However, the present invention is in no way limited by these experimental examples. Unless otherwise specified, the following experiments were conducted at room temperature (25±5°C) and atmospheric pressure. Unless otherwise specified, "%" below means "% by mass" and "parts" means "parts by mass."

Experimental Example 1: Evaluation of the disinfecting effect of an aqueous solution containing a cationic surfactant and stain adhesion to dentures (Part 1)
Concentrated liquid denture cleanser compositions (Examples 1 to 3, Comparative Examples 1 to 4) were prepared by dissolving various cationic surfactants listed in Table 1 in purified water. Using these, the following tests (disinfection test, stain adhesion [coloring] test) were carried out to evaluate the disinfecting effect and stain adhesion.

(1) Experimental method
(1-1) Stain Adhesion Test The following procedure was carried out.
1) Each concentrated liquid denture cleanser composition (Examples 1 to 3, Comparative Examples 1 to 4) was diluted 15 times with tap water to prepare 2 mL of cleaning solution, which was then placed in a 6-well plate. Additionally, as a reference example, purified water was similarly diluted 15 times with tap water to prepare 2 mL of cleaning solution, which was then placed in a 6-well plate.
2) A resin (manufactured by Wada Precision Dental Research Co., Ltd.) (size: 20 mm x 20 mm x 1.5 mm square) that has been previously immersed in artificial saliva for 5 seconds is placed and immersed in 2 mL of the above-mentioned cleaning solution.
3) Allow to stand at room temperature for 30 minutes.
4) After leaving it to stand, the resin is removed from the cleaning solution, and the cleaning solution adhering to the surface is removed with a Kimtowel (manufactured by Nippon Paper Crecia Co., Ltd.).
5) Immerse the resin in an artificial stain solution (2 tea bags added to 600 mL of distilled water, boiled for 10 minutes, instant coffee added, stirred to dissolve, and then cooled to room temperature) and leave to stand for 30 minutes.
6) After leaving it to stand, remove the resin from the stain solution and dry it in a constant temperature bath at 50°C.
7) The above steps 1) to 6) were repeated three times, and the degree of coloration of the resin was visually observed.

(1-2) Bacterial elimination test Using Candida albicans NBRC1595 (purchased from the National Institute of Technology and Evaluation), an evaluation test of the sterilization effect was conducted according to the following procedure. Candida is known to adhere to dentures and cause odors and stains.

(1) Cultivation of Candida albicans NBRC1595 strain Potato dextrose agar medium (Kohjin Bio Co., Ltd.) at 35 ° C. overnight, the strain was suspended in a medium (5% sucrose TSB medium) containing 5% sucrose added to TSB medium (Trypticase Soy Broth, BD Co., Ltd.), and diluted appropriately using a spectrophotometer so that the turbidity at 600 nm (OD600) was 0.150. Next, a 3 × 3 cm PMMA resin plate treated with albumin adjusted to 100 μg / mL was placed in a 6-well plate, one per well, and then 5 mL of the bacterial solution obtained by dilution as described above was added, and the plate was incubated at 35 ° C. for 18 hours to form a biofilm on the resin plate.

(2) Disinfection test After incubation, the resin plate was slowly removed from the well and then immersed for 5 minutes in each concentrated liquid denture cleanser composition (Examples 1 to 3, Comparative Examples 1 to 4) diluted 30 times with purified water (n=6 for each composition). Thereafter, the resin plate was slowly removed and washed with sterilized purified water. Next, the washed resin plate was placed in SCDLP liquid medium (Soybean-Casein Digest Broth with Lecithin & Polysorbate 8, manufactured by Daigo Co., Ltd.), and the biofilm was removed from the resin plate using a cell lifter (manufactured by Violamo Co., Ltd.) and suspended. A 10-fold dilution series was prepared using the resulting suspension, and 100 μL each of the 10-fold diluted solution, 100-fold diluted solution, and 1000-fold diluted solution was smeared on GPLP agar medium (Glucose Peptone Agar with Lecithin & Polysorbate 80, manufactured by Daigo Co., Ltd.), and after 24 hours of incubation at 35 ° C., the number of grown colonies (number of colonies per 1 mL of the suspension) was counted. This was designated as the "number of colonies after washing" in the following formula.

The sterilization rate was calculated using the following formula: Specifically, first, the sterilization rate A for each resin plate was calculated, and the average value of the sterilization rates A for a total of six resin plates was taken as the sterilization rate (%) of the sterilization test.
[formula]
Bacterial elimination rate A (%) = {1 - (number of colonies after washing/number of colonies after unwashing)} x 100

In this formula, the "unwashed colony count" refers to the number of colonies counted in the same manner as the number of colonies after washing, except for the step of immersing the specimens for 5 minutes in each concentrated liquid denture cleanser composition diluted 30 times with purified water in (2) above.

(2) Experimental Results The experimental results are summarized in Table 1.
The test results were evaluated according to the following criteria.

(2-1) Stain adhesion (coloring)
○: The degree of coloring is almost the same as that of the resin treated with the cleaning solution of the reference example (reference resin).
x: The degree of coloring is clearly darker than the degree of coloring of the reference resin.

(2-2) Bactericidal Effect Based on the sterilization rate calculated by the above method, evaluation was performed according to the following criteria. A higher value indicates a higher sterilization rate.
○: Disinfection rate is 99% or more ×: Disinfection rate is less than 99%

As shown in Table 1, it was confirmed that adding a cationic surfactant to a denture cleanser can provide an effective disinfecting effect, but that depending on the type of cationic surfactant used, stains can accumulate on the denture material (Comparative Examples 1 to 4) . It was also confirmed that using a compound in which a nitrogen atom is bonded to a linear carbon chain having 6 to 18 carbon atoms, such as lauryltrimethylammonium chloride, as a cationic surfactant can provide an effective disinfecting effect and suppress or prevent the accumulation of stains on the denture material. Similar trends were also confirmed with compounds in which a nitrogen atom is bonded to a linear carbon chain having 6 to 18 carbon atoms, such as cetyltrimethylammonium chloride and stearyltrimethylammonium chloride.

Experimental Example 2: Evaluation of the disinfecting effect of aqueous solutions containing cationic surfactants and stain adhesion to dentures (Part 2)
Concentrated liquid denture cleanser compositions (Examples 4 and 5, Comparative Examples 5 and 6) were prepared by dissolving various cationic surfactants and other components listed in Table 2 in purified water. Using these, a sterilization test and a stain adhesion [coloring] test were carried out in the same manner as in Experimental Example 1, and the sterilization effect and stain adhesion were evaluated.

The results are also shown in Table 2.

As shown in Table 2, it was confirmed that the use of a compound in which one open carbon chain having 6 to 18 carbon atoms is bonded to a nitrogen atom, such as lauryltrimethylammonium chloride, particularly a quaternary ammonium salt, as a cationic surfactant, not only provides an effective disinfecting effect but also inhibits or prevents the accumulation of stains on denture materials.On the other hand, it was confirmed that cationic surfactants such as quaternary ammonium salts in which two open carbon chains having 6 to 18 carbon atoms are bonded to a nitrogen atom, such as didecyldimethylammonium sulfate, and quaternary ammonium salts having a cyclic carbon chain having 6 to 18 carbon atoms, such as benzalkonium chloride, provide an effective disinfecting effect, but cause stains to accumulate on the denture material and discolor it with use.

Concentrated liquid denture cleanser compositions of the present invention were prepared according to the formulations shown in the table below. These can be diluted 10 to 50 times with tap water before use and used for immersion cleaning of dentures.

Claims (3)

A liquid denture cleanser composition containing 0.1 to 50% by mass of at least one cationic surfactant selected from the group consisting of lauryltrimethylammonium , cetyltrimethylammonium, stearyltrimethylammonium, and salts thereof:
However, the following compositions (1) and (2) are excluded:
(1) General formula (1)
(wherein R1 ^is an alkyl group having 6 or more carbon atoms, R2 ^and R3 ^are alkyl groups having 1 to 6 carbon atoms which may be the same or different, R4 is an alkylene group ^having 1 to 6 carbon atoms, R5 ^, R6 ^and R7 ^are alkyl or alkoxy groups having 1 to 6 carbon atoms which may be the same or different, and X is a halogen ion or an organic carbonyloxy ion) , and
Cationic surfactants (excluding the above silicon-containing compounds)
A cleaning composition comprising
(2) (A) citral 0.002% by mass or more and 0.1% by mass or less; (B) cationic disinfectant 0.001% by mass or more and 0.1% by mass or less; (C) fragrance component other than component (A) 0.35% by mass or less;
An oral composition containing no ethanol or containing 12% by mass or less of ethanol and 0.2% by mass or more and 1.5% by mass or less of polyoxyethylene hydrogenated castor oil,
The oral composition, wherein the cationic antiseptic is at least one selected from the group consisting of lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, and stearyltrimethylammonium chloride. The denture cleanser composition according to claim 1, which has a pH of 5 to 9 at 20°C when diluted with tap water. does not contain a dialkyl (C6 to C20) dimethyl ammonium salt and an alkyl (C6 to C20) dimethyl benzyl ammonium salt, and/or has a content of 0 to 0.03 mass% of at least one compound selected from the group consisting of sodium percarbonate, sodium perborate, hypochlorous acid or a salt thereof, and a sulfite;
3. A denture cleanser composition according to claim 1 or 2.