JPH0320363B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a dentifrice, and particularly to a dentifrice having a bactericidal effect against caries pathogens. [Prior Art] The present applicant discovered that N-type semiconductor has a decomposing effect on dental plaque, and proposed a toothpaste containing N-type semiconductor powder (Japanese Patent Application No. 119955/1989 ”). Although this dentifrice has a remarkable effect on breaking down dental plaque that promotes dental caries, it does
In some respects, it was not necessarily sufficient from the perspective of making a direct attack on (mutans). The reason for this is that the ingredients contain organic substances, so even if N-type semiconductor powder is contained, the energy acts on the organic substances in the dentifrice ingredients during the photocatalytic reaction, reducing the effect by half. In addition, on the surface of the N-type semiconductor, an oxidation reaction occurs due to holes generated by photoexcitation, which steals electrons from the water in the solution and generates OH, but electrons are released from the N-type semiconductor. It is thought that this is because the photocatalytic effect was difficult to obtain. [Problems to be solved by the invention] Therefore, in this invention, by containing N-type semiconductor powder, it has a plaque decomposition effect, and
The emission of electrons from the N-type semiconductor is activated to exhibit sufficient photocatalytic action, and at the same time, the energy during the photocatalytic reaction is used efficiently, so that the N-type semiconductor powder is in contact with the moisture in the oral cavity. The purpose of the present invention is to provide a toothpaste with a novel composition in which OH radicals (.OH) generated when exposed to light have a sufficient bactericidal action to destroy and kill the Myutans bacteria. [Means for Solving the Problems] In order to achieve the above technical problem, the present invention provides a dentifrice that effectively activates the photocatalytic reaction of N-type semiconductor powder by removing organic compounds, particularly A dentifrice is provided, which is characterized in that it contains a mixture of a powdered abrasive that is an inorganic compound, a powdered additive that is an inorganic compound, and an N-type semiconductor powder supported on platinum. The above polishing agent must be an inorganic compound,
Specifically, conventional calcium hydrogen phosphate, heavy or light calcium carbonate, or a mixture thereof may be used. Suitable additives include any auxiliary agents, including inorganic compounds, that enhance the preservability of the dentifrice or enhance its plaque-decomposing action or bactericidal action against the Myutans bacterium. If the content of the N-type semiconductor powder exceeds 20% by weight, the light energy conversion efficiency of the N-type semiconductor powder will deteriorate. Therefore, an N-type semiconductor powder content of up to about 20% by weight is preferred, particularly in the range of about 1 to 20% by weight, and even more preferably in the range of about 5 to 10% by weight. It is said that the composition contains. Furthermore, by applying a dye such as metal phthalocyanine to the N-type semiconductor powder, the usable absorption wavelength range of the semiconductor can be extended to the absorption wavelength range of the dye, and it is possible to measure the light energy conversion efficiency by dye sensitization. In addition to this treatment method, hydrogen reduction at high temperature under hydrogen gas ventilation creates oxygen defects and hydrogen incorporation within the crystal lattice, making it possible to transform the semiconductor into a higher quality semiconductor and further enhance the photocatalytic reaction. strengthened. [Function] The N-type semiconductor powder contained in the dentifrice of the present invention can be prepared by suspending the semiconductor powder in an aqueous solution of chloroplatinic acid with pH adjustment, and irradiating it with light under a nitrogen atmosphere to transfer platinum onto the semiconductor. By supporting platinum using a photoelectrodeposition method in which it is deposited on a metal or a kneading method in which semiconductor powder is kneaded with platinum black, free electrons of platinum are easily released, so it is easy to release electrons from the semiconductor. , thus increasing the reduction reaction. This means that the oxidation reaction on the surface of the N-type semiconductor is also increased. Therefore, the photocatalytic effect will be improved. When this N-type semiconductor is exposed to natural light or artificial light while in contact with saliva in the oral cavity or water used when brushing teeth, for example, when titanium dioxide is used as an example of N-type semiconductor powder,
Through the reaction of equation (1), holes and excited electrons are generated on the surface of titanium dioxide. (h ⁺ indicates a hole.) TiO ₂ +hν→h ⁺ +e ^- (1) The hole generated on the surface of titanium dioxide is caused by an oxidation reaction that takes electrons from the water in saliva, as shown in equation (2). to
Generates OH radicals (・OH). H ₂ O + h ⁺ →・OH+H ⁺ ...(2) On the other hand, the electrons that reached the titanium dioxide surface through the diffusion process undergo a reduction reaction in the presence of dissolved oxygen (3)
As shown in the formula, OH radicals are generated via HO ₂ radicals. H ⁺ +O ₂ +e ^- →・HO ₂ −1/2O ₂ ――――――→ [1/2H ₂ O ₂ ]→・OH ……(3) Dextran, which is the main component of dental plaque, is the following (4) ) It is presumed that it is decomposed into glucose by OH radicals and becomes solubilized. It was confirmed through a culture test that the OH radicals have a bactericidal effect on the Myutans bacteria. Details of this test are as follows. That is, we used physiological saline instead of a culture solution to set up an environment where B. mutans would not grow, and investigated how the amount of bacteria changes depending on the presence or absence of semiconductor powder. A. Experimental procedure (1) Perform preculture in a test tube using the standard method. (2) Add an appropriate amount of preculture solution to the medium (BHI 3.7W/V%
Collect into 100ml of Sucrose (5W/V%) at 37°C.
Perform anaerobic culture. (3) Measure the PH and OD (540nm) of the above culture solution. (4) Prepare two containers, one containing 100 ml of physiological saline, and the other containing 100 ml of physiological saline with 0.1 W/V% of N-type semiconductor powder added. (5) Collect 0.5 ml of the 10 ² -fold dilution of the culture solution whose PH and OD (540 nm) were measured earlier into two containers, and divide into 15 ml portions each. After preparing the sample in this way, (6) Place the sample 1 into the desiccator 2 as shown in FIG. 2 to bring it into an anaerobic state. Also, the liquid temperature was set to 37°C, and irradiation was performed with a 100W mercury lamp 3. (7) Take 0.5 ml of the sample every hour and culture it on a plate agar for about 48 hours on a shear plate. In FIG. 2, number 4 is a water tank interposed between the mercury lamp 3 and the desiccator 2, and number 5 is a stirrer that maintains the sample 1 in the desiccator 2 in a stirring state. B Test results: Two representative examples are shown below. Test results (a) Culture conditions: After 24 hours of preculture, 0.5 ml of a 10-fold dilution of the preculture was collected and incubated for 27 hours. OD (540nm) 0.212 PH 4.55 Number of viable bacteria per 0.5ml 38×10 ⁶ (7.50) (b) Changes in the amount of bacteria over time were as shown in Table 1 below. Test results (a) Culture conditions: After pre-culturing for 25 hours under conditions different from the test results, add 0.5 ml of a 10 ³ -fold dilution of the pre-culture solution.
was collected and cultured for 23 hours. OD (540nm) 0.180 PH 4.55 Number of viable bacteria per 0.5ml 42×10 ⁷ (8.62) (b) Changes in the amount of bacteria over time were as shown in Table 2 below.

[Table] *No colonies were formed even in the stock solution.

〔Effect of the invention〕

According to this invention, the light energy irradiated to the N-type semiconductor powder is effectively used to generate OH radicals in saliva etc. that are in contact with the powder, and these radicals have a plaque decomposition effect and a bactericidal effect. Since a dentifrice composition is provided that allows this to occur, it is possible to achieve a high level of dental hygiene that cannot be achieved using conventional oral cleaning methods.
This is due to the fact that by directly exterminating the bacteria Myutans that produce dental plaque, the subsequent growth of dental plaque is inhibited, and the already formed dental plaque is removed by the decomposition action described above. What should be particularly noted here is that the dentifrice of the present invention is composed only of inorganic compounds, and the OH radicals are contained in organic compounds in conventional dentifrices, such as humectants such as glycerin, lauryl sulfate, etc. There is no risk of unnecessary consumption of foaming agents such as sodium, flavoring agents such as peppermint, or sweeteners such as saccharin. In other words,
Substantially all of the OH radicals are effectively utilized for decomposing dental plaque and destroying the cell membranes of the Myutans bacteria, for example. Moreover, by supporting the N-type semiconductor on platinum, a sufficient photocatalytic action is performed and many OH radicals are generated, so that the above-mentioned bactericidal effect can be further increased. When using the powdered dentifrice of the present invention, there are no particular restrictions on how it can be used, as long as care is taken to avoid its use in combination with any organic compounds.For example, it may be added to water or physiological saline in a pot. It can be decomposed and used as a water toothpaste (using a toothbrush), it can be applied as a powder to areas with a lot of plaque and rubbed with your fingertips, or, of course, it can be applied to the bristles of a toothbrush and used as a conventional toothpaste. It is possible to use the powder like toothpaste, etc. Of course, it is also possible to use it by mixing it into a transparent jelly-like substance. [Examples] Below, several examples of the present invention are shown in Tables 3 to 9. (1) The composition of the dentifrice of Example 1 is shown in Table 3.

[Table] (2) Examples 2 to 7 are shown in Tables 4 to 9, respectively. Example 2 differs from Example 1 in the content of titanium dioxide, and Example 3 differs from Example 1 in the ratio of components other than titanium dioxide. Example 4 is the same as Example 1 except that iron sesquioxide (Fe ₂ O ₃ ), which is harmless to the human body, is used instead of titanium dioxide as the N-type semiconductor powder. In Examples 5 to 7, the proportions of all the components in Example 1 were changed, and in particular, purified water was added to Examples 6 and 7.

【table】

【table】

【table】

【table】

【table】

[Table] The above-mentioned excellent effects were obtained in any of the above examples.

[Brief explanation of the drawing]

The drawings are for explaining this invention, and the drawings are for explaining the invention.
The figure shows the mechanism by which N-type semiconductor powder (titanium dioxide) generates OH radicals, Figure 2 is a partially cutaway front view of the device for testing its bactericidal effect, and Figures 3 and 4 are tests for its bactericidal effect. It is a graph showing the results.

Claims (1)

[Scope of Claims] 1. A dentifrice containing an N-type semiconductor powder supported on platinum that causes a photocatalytic reaction in a dentifrice component consisting of an inorganic compound abrasive and an inorganic compound additive. 2. The dentifrice according to claim 1, wherein the N-type semiconductor powder is obtained by subjecting it to hydrogen reduction treatment. 3. Claim 1 or 2, wherein the N-type semiconductor powder is obtained by subjecting it to dye sensitization treatment.
Toothpastes listed in section. 4. The dentifrice according to any one of claims 1 to 3, wherein the content of the N-type semiconductor powder is about 20% or less by weight. 5. The dentifrice according to claim 4, wherein the content of the N-type semiconductor powder is about 5 to 10% by weight. 6. The dentifrice according to any one of claims 1 to 5, wherein the form of the dentifrice is a toothpaste. 7. The dentifrice according to any one of claims 1 to 5, wherein the target dentifrice is in the form of a semi-toothpaste. 8. The dentifrice according to any one of claims 1 to 5, wherein the form of the dentifrice is powder toothpaste. 9. The dentifrice according to any one of claims 1 to 5, wherein the form of the dentifrice is liquid dentifrice.