US20040171505A1

US20040171505A1 - Cleansers, cleaning system, bleaching agents and compositions for environmental conservation

Info

Publication number: US20040171505A1
Application number: US10/483,269
Authority: US
Inventors: Toru Nonami; Hiroko Hase
Original assignee: Individual
Current assignee: National Institute of Advanced Industrial Science and Technology AIST
Priority date: 2001-07-18
Filing date: 2002-07-18
Publication date: 2004-09-02
Also published as: CN1533245A; WO2003007719A1; KR20040031776A

Abstract

The present invention provides a cleansing, bleaching, and sterilizing agent and a cleansing method for the oral cavity, dental prosthetics, and so forth, and a method for manufacturing said agent, a dental prosthetic cleansing system, a bleaching agent for discolored teeth and a method for manufacturing said agent, a bleaching system, a composition for environmental purification containing a photoactive compound composed of phosphorus and calcium, and a paint using the same.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a harmless, very safe cleansing, bleaching, and sterilizing agent, and more particularly relates to a novel cleansing, bleaching, and sterilizing agent composed of an acid and titanium dioxide, which are safe, harmless materials, and is used for cleansing and bleaching the oral cavity and dental prosthetics, cleansing and sterilizing foods and food containers, cleansing electronic and mechanical components, cleansing and sterilizing articles made of cloth, fiber, or metal, and so forth.

The present invention also relates to a cleansing system for dental prosthetics, and more particularly relates to a system for cleansing dental prosthetics and dental instruments used primarily in the oral cavity, such as dentures that have become stained or scented by nicotine, by foods or beverages such as coffee and curry, by tartar, or the like, and in particular to a dental cleansing apparatus having an optical irradiation function for removing stains, odors, and the like by photocatalytic action, with which the object to be cleansed is placed in a solution composed of a phosphate and a photocatalyst such as titanium dioxide and then irradiated with light.

The present invention also relates to bleaching away colorants (coloration or discoloration) and microbes that have been deposited on teeth, by the action of a compound of phosphorus and calcium. More particularly, the present invention relates to a method for bleaching discolored teeth, in which a bleaching agent composed of a specific composition having optical activity is applied to the surface of discolored teeth, and the teeth are bleached through the photoactive action produced by irradiating this portion with light; to a novel bleaching agent containing a compound of phosphorus and calcium the produces a photoactive action upon optical irradiation and 4% or less hydrogen peroxide and/or an acid such as phosphoric acid or pyrophosphoric acid, which is useful in said bleaching method; to a method for manufacturing said bleaching agent; and to a bleaching system comprising a combination of the above-mentioned bleaching agent, etc.

The present invention also relates to a composition for environmental purification containing a photoactive compound composed of phosphorus and calcium, and more particularly relates to a composition for environmental purification containing a compound composed of phosphorus and calcium that is cytophilic, has adsorptive characteristics, and is photoactive.

The present invention also relates to a paint that contains a compound composed of phosphorus and calcium, which is useful in environment cleaning or preventing the rotting of foods.

In the present invention, “composition for environmental purification” is defined as a composition used in all kinds of environment cleaning applications, such as preventing mold and mildew, deodorizing, preventing staining, or cleaning the atmosphere or water.

2. Description of the Related Art

The problems of dentures becoming stained or scented and the adhesion of microbes to dentures, and how to deal with these problems, have become an increasingly important social concern in our aging society. So far, however, there has been no cleansing agent capable of effectively removing stubborn tartar or tobacco nicotine from dentures, removing odors that seep into dental resins, and killing bacteria that grow in the oral cavity.

In particular, commercially available cleansing agents not only have weak cleansing power, but some of them contain enzymes and other harmful substances, and it is likely that these often have an adverse effect on the user's health and gustatory sensation.

In view of this, some of the present inventors developed a deodorizing dental material (Japanese Patent Application 2000-163679). With this cleansing agent, however, the dispersal of titanium dioxide and the adjustment of pH were not taken into account, so depending on how the product was used, the titanium dioxide powder might precipitate or the components might separate during storage, and some stains could not be removed. A particular problem was how long it took (several hours with sunlight) to obtain an effect in sterilization or the removal of stubborn stains. Furthermore, even though this cleansing agent was over 90% water, when it was concentrated, the large particle size of the titanium dioxide resulted in poor dispersion or the production of secondary particles, and poor pH matching led to the separation or precipitation of components, so this product could not be used in some cases. Also, because the product could not be concentrated, there were situations in which it was difficult to ship or carry around.

Accordingly, effectively resolving the problems encountered with the above-mentioned cleansing agent was deemed an urgent matter, and there was also a need for a material that would be safe and harmless in the cleansing, bleaching, and sterilizing of foods, food containers, and so forth.

Specifically, there has been a great need for the development of a bleaching and cleansing agent that would have excellent deodorizing, sterilizing, and other such effects, would not undergo component separation, and would not undergo precipitation, and more particularly, for an improvement in dispersibility and for a marked increase in cleansing performance through pH control, by such means as controlling the particle size of the titanium dioxide and utilizing titanium dioxide in the form of a sol, in the above prior art.

There has also been a need for a safe, harmless material that would have sufficient effect in the cleansing, bleaching, and sterilizing of tableware and decorative articles. In particular, metal articles become stained through the oxidation of their surface, and removing these stains entails work such as polishing with an abrasive. Expensive silver tableware and decorative articles in particular become blackened or otherwise tarnished as their surface becomes sulfided during use, and therefore require periodic polishing. Silver or an alloy whose main component is silver is used extensively in jewelry, Western tableware, and so forth. However, silver and silver alloys are tarnished by sulfide corrosion become stained during extended use, and end up losing the beautiful luster characteristic of silver. Specifically, silver and silver alloys react with sulfur dioxide or hydrogen sulfide in the air, producing a film composed of silver sulfide on their surface, so that the color of the surface tarnishes yellow or black depending on the thickness of this sulfide film.

In view of this, silver cleaners are marketed for the purpose of removing such stains or tarnish caused by sulfide films. These conventional silver cleaners can be roughly divided into three groups: those whose main component is a surfactant, an abrasive, or sulfuric acid. However, the following problems were encountered with these conventional cleaners.

Although cleaners whose main component is a surfactant are indeed effective on staining caused by handling and so forth, they are not good at removing sulfide films, which are the cause of the yellowing, blackening, and other such tarnishing characteristic of silver and silver alloys. Cleaners whose main component is an abrasive are effective on the above-mentioned sulfide films, but since they remove these sulfide films basically by planing down the silver surface, they required quite a lot of effort, and another drawback is that they damage the surface of silver articles. Furthermore, the fine abrasive powder gets in between fingerprint ridges on the hands during the cleaning work, and once adsorbed, this powder is not easy to wash off.

Meanwhile, cleaners whose main component is sulfuric acid are able to dissolve away sulfide films on silver, but because they contain sulfuric acid, which is an irritant, they are fairly dangerous and not suited to common household use. Another problem is that since silver readily dissolves in these cleaners, if the used cleaner should adhere to the hands, that portion of the hands will turn black. Furthermore, since any other active components present along with the sulfuric acid are decomposed by the sulfuric acid and precipitate, a drawback is that the product is susceptible to modification during distribution and storage.

Moreover, when silver is cleaned with these cleaners, the work is usually performed by hand, including household use situations, and the odor given off by these cleaners themselves is unpleasant. Unfortunately, the generation of odor is unavoidable with a cleaner that makes use of a strong acid such as sulfuric acid or a volatile acid.

It is impossible to polish some articles because they are intricately worked or have a complex shape, and in the case of fingerprints or the like, the staining is sometimes so bad that the article ends up not being used. There are also cleaning liquids, but these are strongly acidic, and in the case of decorative items, these products may damage stones or the like. There are also methods such as removing sulfide films from a surface by dipping or wiping a silver article in or with an aqueous solution of an acid such as thiouric acid, phosphoric acid, or citric acid (Japanese Laid-Open Patent Application H10-046375). With these methods, though, the cleaning effect is not sufficient, and severe stains, odors, and microbes cannot be removed. The laundering of cloths normally involves a detergent used in a washing machine. However, depending on the type of cloth, it may be damaged or faded by mechanical agitation or the detergent. In particular, it is not unheard of today for a person not to have a washing machine due to circumstances such as living alone or limited living space, and there is a need for a detergent that would provide a cleaning effect, antibacterial effect, and deodorizing effect without the use of a washing machine for the laundering of daily items such as underwear and handkerchiefs, merely by soaking.

The average lifespan today continues to lengthen, but the reduction in the proportion of people who lose their teeth is not keeping pace with this trend, and there will only be increasing demand in the future for a cleanser for dentures and other such dental prosthetics. In particular, eliminating denture staining and bad breath caused by the use of dentures, for example, is essential for senior citizens to lead their lives with self-confidence, and there is a tremendous need for the development of a cleanser that would provide an excellent cleansing effect while also being very safe to use.

Some of the causes of dental prosthetic staining include. stains and odors resulting from tobacco or foods and beverages, staining resulting from tartar, mutin, or microbes, and staining due to coloration.

The following methods are examples of ways to remove such stains from dental prosthetics.

1) Mechanical Cleaning

Mechanical cleaning with a brush is the most basic way to remove stains, and examples include the use of denture brushes and clasp cleaning brushes.

However, care must be taken when cleansing with a brush because the brush can excessively abrade areas such as the denture saddle. Brushes with long bristles are generally more prone to abrasion, but this can be prevented by employing the proper brushing technique. Plaque generally will not be completely removed merely by cleaning with a toothbrush by a patient. In particular, microbes infiltrate resins and tissue conditioners. Mechanical cleaning by brushing alone will be insufficient to remove this plaque.

2) Ultrasonic Cleaning

Portable ultrasonic cleaners are commercially available, but just as with mechanical cleaning by brushing, the cleaning effect with these alone is inadequate, and in actual practice microbes are detected even after cleaning. Therefore, ultrasonic cleaning must be combined with chemical cleaning.

3) Chemical cleaning

Examples of components used for chemical cleansers include peroxides, hypochlorous acid, acids, enzymes, and disinfectants. Of these, peroxides are the most widely used. Examples of the foaming mechanism of these peroxides include an alkaline type that generates oxygen gas as follows:

H₂O₂+OCl - - - O₂+H₂O+Cl⁻

and a neutral type that generates carbon dioxide gas as follows:

NaHCO₃+H⁺ - - - CO₂+H₂O+Na⁺.

Of these, the alkaline type is effective on coloration stains, but can have a harmful effect on denture materials, while the neutral type is effective on juvenile plaque, but has no effect on coloration staining. This type is commonly found in commercial products.

As for hypochlorous acid, examples of its foaming mechanism include an alkaline type that generates oxygen gas as follows:

OCl⁻+H₂O₂- - - O₂+H₂O+Cl⁻

and a neutral type that generates carbon dioxide gas as follows:

NaHCO₃+H⁺- - - CO₂+H₂O+Na⁺.

These eliminate coloration, dissolve mutin and organic matter, and have a sterilizing effect on bacteria and fungi. Nevertheless, the use of these products may cause the corrosion of metal or the bleaching of resin.

Acids that have been utilized include hydrochloric acid and phosphoric acid. These are extremely effective at removing coloration and tartar. However, a problem with the use of these acids is that they corrode metals.

Enzymes that have been used include digestive enzymes such as protease, amylase, and lipase, and mutanase, dextranase, β-1,3-glucanase, lysozyme, and the like that have antibacterial and antiplaque effects. These do not have tremendous cleansing action, but they are not very harmful to denture materials and are well suited to tissue conditioners.

Disinfectants are also used, but these are generally not available. These have an antibacterial effect, but another problem is damage caused by any killed microbes that remain behind.

Synthetic surfactants and bleaching agents generally have the property of irritating the skin and mucous membranes, and if their cleaning of dentures is inadequate, their use can lead to irritation of the mucous membranes or the tongue in the oral cavity, or to damage such as impaired gustatory sensation.

As discussed above, various cleansing methods and cleansing agents have been used in the past, but with all of these conventional cleansing agents there is the possibility of inadequate removal of stains, tartar, microbes, and so forth, and if the same cleansing agent is used continuously for an extended period, there is the potential for problems such as allergies, and there is an urgent need in this field of technology for the development of a novel cleansing technique that is free of these problems.

In recent years there has been growing demand for improvement in so-called cosmetic dental treatment, in which the patient seeks an improvement in tooth configuration, alignment, matching, and so forth. In light of this, there has recently been a growing number of cases in which dental treatment is sought out of a desire to whiten the teeth, which is considered an important element of beauty among young women. Causes of discoloration, pigmentation, and staining of teeth can be roughly divided into those known as extrinsic factors, such as the precipitation of colored substances (such as tobacco or tea), chromogenic microbes, coloration of repairs (primarily composite resins), and metal salts (primarily amalgams, silver sulfate, and ammoniacal silver), and those known as intrinsic factors, such as aging, chemical substances and drugs (such as fluorine and tetracycline), metabolic errors, hereditary disorders, and injury to a tooth. However, in dental prevention and treatment, bleaching is most often applied to discolored teeth belonging to the latter group (intrinsic factors).

Several methods have been proposed in the past as ways to improve the esthetics of discolored teeth, but of these, bleaching, if properly performed by selecting the method best suited to each individual case, can be considered the treatment that best preserves the dentine, although some problems may be encountered, such as occasional reoccurrence. Bleaching is basically a method in which a colored substance is rendered colorless by a chemical reaction, and various kinds of bleaching agents composed of various chemical agents, as well as bleaching methods that make use of these, have been proposed in the past, which can be classified as either vital bleaching or non-vital bleaching.

Examples of these methods are given below.

There is a bleaching method in which 30% H ₂O₂is used as the chemical agent, and light and heat are used together with this hydrogen peroxide. With this method, a strip of gauze soaked with 30% H₂O₂is placed over the lip surface and irradiated for 30 minutes from two 500 W photographic lamps on the right and left. With this method, the lamps must be brought in as close as possible, and the H₂O₂replenished about every 5 minutes so that the gauze will not dry out.

There are also a tooth bleaching agent and bleaching method in which hydrogen peroxide is mixed with orthophosphoric acid (Japanese Laid-Open Patent Application H8-143436/1996), a bleaching agent in which hydrogen peroxide is mixed with silicic anhydride, and a vital bleaching method in which the teeth are coated with this bleaching agent (Japanese Laid-Open Patent Application H5-320033/1993), a tooth bleaching composition composed of a tooth bleaching agent (such as urea hydrogen peroxide, hydrogen peroxide carbamide, or carbamide peroxide) and a matrix material (such as carboxymethylene), and a method for bleaching teeth by using this composition (Japanese Laid-Open Patent Application H8-113520/1996), and many others.

In the bleaching of teeth, the bleaching method and bleaching agent must satisfy the following conditions.

(a) The bleaching effect must be pronounced, (b) the chemicals used must not be toxic, (c) the work must be easy, (d) the properties of the dentine must not deteriorate after the procedure, (e) the treatment must be effective on both live and dead teeth, and (f) the bleaching effect must appear within a short time. If a bleaching method satisfied all of the above conditions, it would be possible to improve cosmetics while maintaining the configuration of the teeth, and the improvement effect thereof would be pronounced. With conventional bleaching methods, however, the primary agent is 30 to 35% aqueous hydrogen peroxide, which is highly corrosive to tissue, and the bleaching is based on the oxidizing action of this agent. At the present time, as discussed above, the various kinds of bleaching being performed here in Japan can all be considered to involve a combination of 30 to 35% aqueous hydrogen peroxide, various instruments, and other chemicals. One of the bleaching methods being performed in the United States makes use of 10% urea peroxide, and uses no 30 to 35% aqueous hydrogen peroxide, but this also poses problems with efficacy and safety, and at the present time is pending in court and has not been approved in Japan.

In addition, there is a method in which the teeth are coated with fluoroapatite after bleaching has been performed with hydrogen peroxide as above, which recalcifies and restores roughened enamel. Unfortunately, even with this method enamel that has been modified once cannot be completely restored.

Japanese Patent 3,030,380 discloses a method for bleaching discolored teeth, wherein a solution/paste of titanium dioxide powder and aqueous hydrogen peroxide is applied to the surface of the discolored teeth, and the teeth are bleached through the photoactive action produced when this area is irradiated with light. This method bleaches by directing light at a bleaching agent obtained by compounding hydrogen peroxide in a low concentration of no more than 3% with titanium dioxide, which causes no harm to the body, and does not use hydrogen peroxide in a dangerously high concentration as in a conventional method. This is safe and simple, and furthermore the effect is pronounced. However, there is a need for a bleaching agent with better affinity to enamel and with which bleaching can be performed more efficiently. The inventors of the present invention have proposed a method for bleaching teeth with hydrogen peroxide and titanium dioxide whose surface has been covered with apatite (Japanese Patent Application 2000-344640). The biocompatibility of the apatite improves conformance with the enamel and affords better bleaching. Here again, though, because the proportion of apatite is so low, conformance with the enamel is still inadequate, and there is therefore a need for a method with which bleaching can be performed more efficiently.

The bleaching effect is weak with commercially available apatite such as that produced by a conventional wet method or the like, so there are some cases involving non-caries pulp extraction. Also, when an attempt is made to use highly toxic 30 to 35% aqueous hydrogen peroxide and titanium dioxide in various bleaching methods, various limitations are imposed on the work and so forth, and in particular there has been indicated a limit to the bleaching effect on medullated teeth. Therefore, at present there is an urgent need for the development of a novel bleaching agent that has excellent safety, ease of use, and biocompatibility, that is effective on both medullated and nonmedullated teeth in a short time, and that will not damage enamel.

Products that make use of apatite have become prominent in recent years. Apatite is capable of adsorbing microbes and proteins, and this characteristic has been utilized in commercial products such as influenza masks, protein separation columns, and hand creams. Because of its ability to adsorb nitrogen oxides and aldehydes, apatite holds particular promise as a composition for environmental purification.

However, apatite merely adsorbs substances and does not decompose them, so a drawback is that it eventually reaches saturation and no longer functions, and up to now it has been used mainly in disposable applications. Consequently, its use as a composition for environmental purification in building materials, for example, posed difficulties.

As for methods for manufacturing apatite, there has also been proposed a compounding technique on the atomic level as a method for manufacturing a metal-modified apatite, comprising the compounding of apatite such as hydroxyapatite with a metal oxide having a photocatalytic action, that is, ion exchange between some of the metal ions in apatite crystals with the metal ions of a metal oxide having a photocatalytic action (such as titanium ions in the case of titanium oxide) (Japanese Laid-Open Patent Application 2000-327315). As a result, a metal oxide having a photocatalytic action is formed by ion exchange in an apatite crystal structure, which provides a metal-modified apatite that allows a novel photocatalyst function to be exhibited by further developing the catalyst function had by various kinds of apatite such as calcium hydroxyapatite, and at the same time allows the excellent distinctive adsorption characteristics with respect to organic substances and other such specific adsorption substances, which originate in the apatite. This method, though, has a fundamental problem in that the photocatalyst function is not readily exhibited because the titanium dioxide or other photocatalyst metal oxide is compounded within the crystals of apatite. It is therefore difficult to obtain the photocatalytic activity required for an environment cleaning material or the like, and the effect of the photocatalyst is weak, so in actual practice this method is difficult to use, and there has been a need for the development of an apatite material with better photocatalytic activity.

Meanwhile, a compound material obtained by coating titanium dioxide, which has a photocatalytic action and has been applied as a composition for environmental purification, with apatite has been proposed (Japanese Laid-Open Patent Application H10-244166).

This composition for environmental purification can be formed by immersing titanium oxide particles or a substrate to which a titanium oxide film has been applied in a simulated body fluid whose composition, pH, and so forth have been adjusted so as to facilitate the production of a film of porous calcium phosphate. This promises to afford maintenance-free, semi-permanent usage because the apatite adsorbs substances and the titanium dioxide decomposes them.

More recently, there have been reports that hydroxyapatite itself is what is known as photoactive, meaning that it generates active oxygen by the activation of oxygen under optical irradiation. However, this photoactive function of apatite only “seems” to exist, in that it can only be confirmed by measurements on the laboratory level, and far from being put to practical application, this can barely be utilized in actual practice. At any rate, imparting photoactivity to apatite having the ability to adsorb various kinds of substance has been greatly desired in this field of technology as the key to a novel, maintenance-free composition for environmental purification.

SUMMARY OF THE INVENTION

In the midst of this situation, and in light of the prior art discussed above, the inventors conducted diligent research aimed at developing a novel cleansing, bleaching, and sterilizing agent with which the problems encountered with the above prior art could be effectively solved, and as a result perfected the present invention upon discovering that the dispersibility of titanium dioxide can be improved and that pH can be controlled so as to enhance cleansing performance, by combining titanium dioxide having a photocatalytic function with an acid such as phosphoric acid or pyrophosphoric acid.

It is an object of the present invention to provide a novel cleansing, bleaching, and sterilizing agent capable of removing stains, odors, microbes, and so forth with a simple operation.

Also, in light of the past situation described above, it is an object of the present invention to provide a silver or cloth cleaner with which a sulfide film can be removed from silver or a cloth can be cleaned merely by soaking or another such simple process, the article can be stored for extended periods in a chemically stable fashion, and the process is safe and odorless and has no adverse effects on the human body or the environment.

Also, in light of the prior art discussed above, as a result of diligent research aimed at developing a novel technique for cleaning dental prosthetics with which the above-mentioned problems encountered with prior art could be effectively resolved, the inventors arrived at the present invention upon discovering that the desired object could be achieved by using light comprising a combination of ultraviolet light and visible light of a specific wavelength band as the light used for optical irradiation in a dental cleansing system that makes use of a specific cleaning solution having a photocatalytic action.

It is an object of the present invention to provide a cleansing agent for dental prosthetics, which effectively removes stains and odors and is also highly safe, so that the dental prosthetic is not damaged, in the cleansing of a dental prosthetic with a cleansing agent containing titanium dioxide and/or apatite-covered titanium dioxide, phosphoric acid, sodium pyrophosphate, or the like. It is another object of the present invention to provide a cleansing system for dental prosthetics, with which cleansing can be performed using an irradiation device having an irradiation function using light of a specific wavelength band, in the cleansing of dentures and other such dental prosthetics utilizing a photocatalyst.

Also, the inventors arrived at this invention upon discovering that a compound of phosphorus and calcium precipitated in a simulated body fluid exhibits excellent photoactivity and biocompatibility, and a pronounced bleaching effect and antibacterial effect. Specifically, as a result of diligent research aimed at establishing a novel bleaching method that would afford excellent safety and ease of use, and would also have a pronounced bleaching effect, the inventors arrived at the present invention upon discovering that the desired object can be achieved by using as an active component a compound of phosphorus and calcium such as apatite which has photoactivity, and is a component present in the body and therefore provides excellent biocompatibility.

Specifically, it is an object of the present invention to provide a novel bleaching agent that is safe and easy to use and that is effective on both medullated and nonmedullated teeth in a short time.

It is another object of the present invention to provide a method for manufacturing the above-mentioned bleaching agent, and a dental bleaching system that makes use of this bleaching agent.

Further, the inventors arrived at the present invention upon discovering that these materials, which have higher activity than ordinary compounds composed of phosphorus and calcium, can be utilized as environment cleaning materials and so forth, and that a compound composed of phosphorus and calcium such as apatite in the form of a sheet or ribbon precipitated from a simulated body fluid has markedly higher activity than ordinary compounds composed of phosphorus and calcium, and exhibits sufficient photoactivity to be used as an environment cleaning material.

It is an object of the present invention to provide a composition for environmental purification containing a compound composed of phosphorus and calcium and having an adsorption function and enough photoactivity for environment cleaning.

It is a further object of the present invention to provide a paint containing the above-mentioned compound composed of phosphorus and calcium, and an article coated with this paint.

The present invention will now be described in further detail.

If titanium dioxide is used in the form of a powder, it will precipitate or separate when made into an aqueous solution. It is therefore preferable to use a sol solution of an acid such as nitric acid, an alcohol, or water. Using a sol improves the dispersibility of the titanium dioxide, and when it is diluted into a cleansing agent, the deodorizing, antibacterial, and stain removal effects are all excellent. A powder is undesirable because of its poor dispersion, but the cleansing strength of a powder can be increased by reducing its particle size. If the particle size is large, the particles tend to precipitate or separate, and precipitation occurs particularly readily if the particle size is over 70 nm. On the other hand, if the particles are smaller than 0.1 nm, they tend to clump together into secondary particles that precipitate. It is therefore preferable for the particle size of the titanium dioxide to be from 0.1 to 70 nm, and 1 to 50 nm is even better. When the dispersibility of the titanium dioxide improves, there is an increase in the cleansing effect because of the higher probability that the titanium dioxide will come into contact with the dental prosthetic.

With the present invention, it is possible to produce a concentrated cleansing agent aqueous solution by following the particulars specified as the constitution of the present invention.

If this constitution is deviated from, the particles may precipitate and not disperse well when diluted. Concentrating the cleansing agent aqueous solution makes the product lighter, smaller, and easier to transport and carry around, which increases its commercial value. This cleansing agent aqueous solution may be used directly or after being diluted.

It was also found that using a so-called concentrated solution or pellets of this cleansing agent, either diluted or not, after the lapse of at least 2 hours from the time of production greatly enhances the increase in dispersibility and markedly increases cleansing strength. Specifically, the affinity improves between the titanium dioxide and the phosphoric acid or other constituent substances, which improves dispersibility and increases cleansing strength.

When titanium dioxide, phosphoric acid, pyrophosphoric acid, or other such constituent substances are mixed, the mixing should be performed at a temperature of at least 25° C., and it should be performed while ultrasonic or other vibration is imparted, which results in better mixing and a more uniform solution.

The cleansing agent of the present invention may be used not only to cleanse dental prosthetics, but also to bleach teeth in the oral cavity, for example. Its use is not limited to dental applications, and it can also be used in industrial and medical applications. The usage method may involve cleansing a dental prosthetic or treatment instrument, an industrial product, or the like by soaking it in the diluted or undiluted cleansing agent, but other methods are also possible.

Also, with the present invention, metals or cloths can be cleansed by soaking them in the diluted or undiluted cleansing agent.

The deterioration of fibers and so forth that occurs when fibers or the like are treated with a photocatalyst can be prevented by coating the photocatalyst surface of titanium dioxide with a compound composed of at least one A _x(BO_y)_zX unit (where A is one or more metal atoms selected from among Ca, Co, Ni, Cu, Al, La, Cr, Fe, and Mg, B is a phosphorus or sulfur atom or both, X is at least one member of the group consisting of OH, halogen atoms, and CO₃, x is a number from 8 to 10, y is a number from 3 to 4, and z is a number from 5 to 7) having optical activity (photo-oxidation function). Further, Ca₉(PO₄)₆, which is a favorable example of the above-mentioned compound, adsorbs harmful substances, and this adsorption function needs no light. If light does strike the material, the Ca₉(PO₄)₆or titanium dioxide will exhibit a decomposition function, which allows the material to be deodorized and sterilized.

The particle size of the titanium dioxide is from 0.1 to 70 nm, and ideally about 6 nm. Below this range, the particles will tend to form secondary particles and precipitate or separate, whereas above this range the particles will be so heavy that they will precipitate. Preferably, the particle size of the titanium dioxide is from 1 to 50 nm. The titanium dioxide will remain stably dispersed over an extended period if the particle size is within this range. Above or below this range, precipitation or separation may occur during long-term storage.

If possible, the titanium dioxide should be used in the form of a sol solution. If a sol solution is used, there will be basically no precipitation of titanium dioxide over time. The titanium dioxide content in the sol solution is ideally about 0.01 to 80%, optimally about 33%. If the titanium dioxide content in the sol solution is below this range, the amount of solvent will increase to the point that the titanium dioxide has only minimal effect, but above this range precipitation will tend to occur. Preferably, the titanium dioxide content in the sol solution is from 5 to 75%. The pH of the sol should be from 1 to 8. Outside this range, precipitation will occur when the titanium dioxide is mixed with the acid to produce a cleansing liquid. Preferably, the pH of the sol is from 1 to 5. Outside this range, separation will tend to occur at elevated temperatures or if the mixing is not uniform.

“Dispersibility is good” as used here means that the titanium dioxide is present in the solution in the form of single particles, or of secondary particles no larger than 1 micron, and preferably no larger than 500 nm.

With the present invention, an outstanding cleansing effect can be obtained by using a sol solution of titanium dioxide to improve dispersibility.

Regardless of the composition of the mixture, the titanium dioxide content is between 0.01 and 10%, and ideally 1.1%. If the proportion of titanium dioxide is below this range, the titanium dioxide will have no effect as a photocatalyst, but above this range, light will not be able to pass through, so there will be no effect. This proportion is preferably from 0.05 to 3%, even more preferably 1.1%, and ideally from 0.7 to 1.5%. Below this range there will tend to be no effect and the process will take longer, but above this range precipitation will tend to occur.

Further, titanium dioxide that has been compounded with calcium phosphate as discussed below can be used in the present invention.

This compounded titanium dioxide is, for example, titanium dioxide on whose surface calcium phosphate crystals have been deposited, with the calcium phosphate accounting for 0.001 to 200% with respect to the titanium dioxide, or is apatite, OCP, TCP, or a mixture thereof in which the calcium phosphate crystals are in the form of plates or columns. In this case, it is preferable if the calcium phosphate crystals do not completely cover the surface of the titanium dioxide, so that part of the titanium dioxide surface remains exposed. This is because the photocatalyst effect will be lost if the calcium phosphate crystals completely cover the surface of the titanium dioxide. Therefore, it is preferable for 0.001 to 99% of the surface area of the titanium dioxide to be covered by the calcium phosphate. When titanium dioxide is immersed in a simulated body fluid containing phosphoric acid ions and calcium ions, calcium phosphate is deposited on the surface of the titanium dioxide.

The compound composed of at least one A _x(BO_y)_zX unit and having photoactivity (photo-oxidation function) used in the present invention will now be described by using as an example Ca₉(PO₄)₆having photoactivity (photo-oxidation function). This contains at least one of the above-mentioned Ca₉(PO₄)₆as the minimum unit. The structure may comprise just the Ca₉(PO₄)₆units clustered together, or OH, fluorine, chlorine, or the like may be contained at the same time. Part of the calcium may be substituted with chromium, iron, or another such metal, and part of the phosphorus may be substituted with titanium, aluminum, or the like. This material may be either crystalline or amorphous. If it is crystalline, it may be apatite or tricalcium phosphate, octacalcium phosphate, or other such calcium phosphate crystals. The apatite here is hydroxyapatite, fluoroapatite, or the like.

As long as it has photocatalytic activity, the titanium dioxide photocatalyst may be either an anatase or rutile type. The titanium dioxide may be any ordinary titanium dioxide used as a pigment or as a photocatalyst. The particle size is from 1 nm to several millimeters. It may also be another oxide semiconductor having photocatalytic activity. As for its form, it may be a powder or a thin film. One or more of the above-mentioned Ca ₉(PO₄)₆units should be adhering to the surface of the photocatalyst. The adhesion may be at a single site or a number of different sites, or the units may be dispersed in stripes. Also, the above-mentioned Ca₉(PO₄)₆units may be stacked in a number of layers to form an amorphous or crystalline phase.

This compound composed of at least one Ca ₉(PO₄)₆unit and having photoactivity (photo-oxidation function) is most preferably produced from a simulated body fluid containing at least phosphorus and calcium. Specifically, clusters of Ca₉(PO₄)₆are produced in a simulated body fluid by controlling the composition of the simulated body fluid, and these clusters group together to produce a compound. If the substance to which the titanium dioxide powder or other such compound composed of at least one Ca₉(PO₄)₆unit is to be bonded is dispersed, suspended, or immersed in a simulated body fluid, the compound composed of at least one Ca₉(PO₄)₆unit will adhere to the surface thereof. This may be just one unit or a plurality of units. In the latter case, the produced compound will be composed of one or more amorphous or crystalline Ca₉(PO₄)₆units. This compound can be apatite, tricalcium phosphate, or the like, but basically any such compound can be used. The Ca₉(PO₄)₆having photoactivity (photo-oxidation function) is excellent in terms of its adsorption of substances such as bacteria, viruses, aldehydes, ammonia, and other harmful substances.

The size of the compound composed of at least one Ca ₉(PO₄)₆unit is preferably from 0.01 nm or 50 μm. A range of 0.1 nm or 10 μm is better yet. It is preferable for 1 to 99% of the surface of the titanium dioxide to be covered with the compound composed of at least one Ca₉(PO₄)₆unit.

If nothing is added to the simulated body fluid, the Ca ₉(PO₄)₆clusters will group together and produce this compound.

The term “simulated body fluid” as used in the present invention refers to a working fluid that gives a calcium phosphate compound expressed by various rational formulas, such as tricalcium phosphate (Ca ₃(PO₄)₂). This working fluid is prepared, for example, by dissolving NaCl, NaHCO₃, KCL, K₂HPO₄.3H₂O, MgCl₂.6H₂O, or CaCl₂and Na₂SO₄, NaF, or the like in water. It is preferable to adjust the pH to between 7 and 8 with HCl, (CH₂OH)₃CNH₂, or the like. A pH of 7.4 is particularly favorable. The Ca²⁺ ion concentration in the simulated body fluid used here is preferably 0.1 to 50 mM, and the phosphoric acid ion concentration is preferably 0.1 to 20 mM.

The particle size of the composite material of calcium phosphate and titanium dioxide is from 0.1 to 70 nm. Below this range, the particles will tend to form secondary particles and precipitate or separate, whereas above this range the particles will be so heavy that they will precipitate. Preferably, the particle size of the composite material should be 1 to 50 nm. The composite material will remain stably dispersed over an extended period if the particle size is within this range. Above or below this range, precipitation or separation may occur during long-term storage.

If possible, the composite material should be used in the form of a sol solution, as there will be basically no precipitation over time. The titanium dioxide content in the sol solution should be about 0.01 to 80%. Below this range, the amount of solvent will increase to the point that the composite material has only minimal effect, but above this range precipitation will tend to occur. Preferably, the composite material content in the sol solution is from 5 to 75%. The pH of the sol should be from 1 to 8. Outside this range, precipitation will occur when the composite material is mixed with the acid to produce a cleansing liquid. Preferably, the pH of the sol is from 1 to 5. Outside this range, separation will tend to occur at elevated temperatures or if the mixing is not uniform.

“Dispersibility is good” as used here means that the composite material particles are present in the solution in the form of single particles, or of secondary particles no larger than 1 micron, and preferably no larger than 500 nm. An outstanding cleansing effect can be obtained by using a sol solution to improve dispersibility. Regardless of the composition of the mixture, the composite material content is between 0.01 and 10%. Below this range, the titanium dioxide will have no effect as a photocatalyst, but above this range, light will not be able to pass through, so there will be no effect. This proportion is preferably from 0.05 to 3%, and ideally from 0.7 to 1.5%. Below this range there will tend to be no effect and the process will take longer, but above this range precipitation will tend to occur.

The phosphoric acid concentration is from 1 to 50%, and preferably from 3 to 50%. Below this range the phosphoric acid will have no effect of removing stains, but above this range the article being cleansed may be damaged (rusting, fading, or the like) by the acid. The ideal range is from 20 to 45%, within which cleansing, bleaching, and sterilizing can be performed favorably without damage to the article.

The pyrophosphoric acid concentration is from 1 to 50%. Below or above this range, the pH cannot be adjusted. A preferable range is from 30 to 80%, and an ideal range is from 50 to 75%, within which the pH can be controlled well. A favorable example in terms of safety here is tetrasodium pyrophosphate, which is a food additive.

Other acids can also be used instead of the above-mentioned phosphoric acid and pyrophosphoric acid if desired. Favorable examples include polyphosphoric acid, tripolyphosphoric acid, acetic acid, citric acid, tartaric acid, malic acid, formic acid, gluconic acid, cinnamic acid, succinic acid, oxalic acid, nitric acid, hydrochloric acid, sorbic acid, sulfuric acid, lactic acid, folic acid, and butyric acid.

For example, three of the above can be weighed out and mixed under agitation at 25° C. or higher, and preferably from 30 to 40° C., with a spoon, agitator, mixer/grinder, or the like. Ultrasonic or other vibration is preferably imparted here. After mixing, the mixture is allowed to stand for at least 2 hours. In this case, the time may be from 2 hours to about 1 minute, but the longer the better.

The pH of this cleansing agent solution is preferably between 1 and 7. Outside this range the titanium dioxide may separate.

Preferably, the pH of the cleansing agent solution is between 1 and 4. Outside this range separation may occur during long-term storage.

The above-mentioned cleansing agent solution is preferably shielded from some wavelengths of light during its shipping and storage, and particularly from light of 400 nm or less. Preferably, all the light is blocked. In specific terms, the above-mentioned cleansing agent solution is placed in a pouch or bottle made of plastic, glass, or metal. If the solution is exposed to light here, its components may separate and the titanium dioxide may precipitate.

The above-mentioned cleansing agent solution can be used directly as it is in the cleansing of dental prosthetics or the bleaching of teeth, for example. The solution may be applied and then exposed to light, or the article to be cleansed may be coated after the solution has been diluted between 3 and 1000 times, or the article may be cleansed by soaking. If the solution is more dilute than this, it will have not effect, but if it is less dilute than this, it will have such a high viscosity that it cannot be used as a cleansing solution, and furthermore may damage the article. A preferable dilution range is from 10 to 100 times, and an ideal range is 20 to 50 times, within which cleansing can be performed extremely well. Outside these ranges it may be impossible to remove certain stains, bacteria, and so forth.

This cleansing agent solution may also be used in dry form. To dry the cleansing agent solution and produce pellets or tablets, an organic or inorganic binder may be added.

Optical irradiation may be performed during bleaching and cleansing. In this case, as long as the light includes a component with a wavelength of 450 nm or less, any kind of light can be used, such as sunlight, fluorescent light, black light, xenon light, halogen light, metal halide light, or light from an LED.

An advantage to the cleansing solution of the present invention is that because of the good dispersibility of titanium dioxide, the cleansing and bleaching effects are superior to those of conventional cleansing agents and bleaching agents containing titanium dioxide. Furthermore, shipping and transportation costs can be lowered by concentrating the solution. With a conventional product, the pH, the form of the titanium dioxide, and so forth could not be controlled, so concentration led to the problem of separation or precipitation of the components, but an advantage of the cleansing, bleaching, and sterilizing agents of the present invention is that they are free of this problem.

The present invention also relates to a cleansing system for dental prosthetics, comprising a combination of an irradiation device with an optical irradiation component having the function of emitting visible purple light and/or ultraviolet light. In the present invention, examples of the article to be cleansed include dental prosthetics and dental instruments, although this list is not intended to be comprehensive. With the present invention, it is important in this cleansing system that the light emitted from the optical irradiation component have a wavelength of 200 to 800 nm at said optical irradiation component, that light with a wavelength of 430 to 800 nm account no more than 70% of the light with the above wavelength, and that the energy at 380 nm and lower be at least 10 mW/cm ². The cleansing system of the present invention has a container for holding the cleansing agent and an optical irradiation component with an optical irradiation function, as well as a light source, a filter, control means, and so forth, and the light source, filter, control means, and so forth can be selected as needed, with no particular limitations thereon.

The optical conditions at the above-mentioned optical irradiation component of the apparatus of the present invention are set so as to allow cleansing to be accomplished within about 20 minutes to 10 hours in a dental prosthetic cleansing apparatus with which a dental prosthetic is soaked in a container holding a cleansing agent that contains titanium dioxide and/or apatite-covered titanium dioxide, and the article to be cleansed is irradiated with light emitted from a light source.

Specifically, these conditions are determined by taking into account that a cleansing agent solution containing titanium dioxide and/or apatite-covered titanium dioxide has a good cleansing action at wavelengths of 380 nm and lower, and that when the irradiation energy drops below 10 mw/cm ², the energy is so low that cleansing takes an extremely long time, and that if the energy is above this level, a cleansing effect can be achieved in 10 hours or less.

The reason energy of 380 nm or lower has a good cleansing action is that titanium dioxide is activated by energy of 380 nm or lower and generates active oxygen, and this active oxygen decomposes organic matter.

Further, the irradiation energy of light with a wavelength of 430 to 800 nm must account for no more than 70% of the light with a wavelength of 200 to 800 nm.

This condition is necessary in order to reduce the proportion of light of 430 nm or greater, which is a cause of heat generation. Temperatures no less than 60° C. are undesirable for resins and so forth, and may lead to deformation or discoloration.

A cleansing agent solution composed of titanium dioxide and/or apatite-covered titanium dioxide is used in the present invention, and examples of favorable compositions thereof include a solution composed of titanium dioxide (as a photocatalyst) and a phosphate, and a solution composed of apatite-covered titanium dioxide, a phosphate, a titanium dioxide powder, and phosphoric acid, pyrophosphoric acid, or another such acid. In this case, examples of the titanium dioxide and/or apatite-covered titanium dioxide include one in the form of a sol or microparticles with a size of 1 to 10 μm, which preferably is mainly an anatase type. Microparticles or a sol will afford good dispersibility, so the particles will be less apt to precipitate during cleansing, there will be a higher probability that the titanium dioxide will come into contact with the dental prosthetic, and a better cleansing effect can be anticipated. The weight ratios of these components are 0.01 to 10% titanium dioxide and/or apatite-covered titanium dioxide, 1 to 50% phosphoric acid, and 30 to 50% pyrophosphoric acid, but these can be varied as needed according to the extent of staining and other such factors.

The article to be cleansed is immersed in the above-mentioned solution, and this solution is irradiated with light. The duration of this irradiation is from 20 minutes to 10 hours, and preferably at least 1 hour, but can be adjusted as appropriate depending on the extent of staining, the size of the article, and other factors. The direction in which the light is emitted can be from above the article being cleansed, from the side, or from below, or from a plurality of directions, and no particular limitations are imposed thereon.

The apparatus constituting the cleansing system of the present invention comprises a container component that holds the cleansing agent solution, an irradiation component having a function of irradiating a dental prosthetic soaking in the above-mentioned cleansing agent solution with light of a specific wavelength, a light source (lamp), a lid component that openably covers the opening at the top of the container component, a filter that selects the wavelength of the light source, a tray on which the dental prosthetic is placed, control switches, and so forth. There are no particular restrictions on the shape, structure, etc., of these constituent elements, and each can be selected as appropriate. Favorable examples of light sources include an LED, metal halide lamp, halogen lamp, xenon lamp, black light, fluorescent light, and sunlight.

An example of a control switch is one that prevents light from leaking to the outside when dentures or another such dental prosthetic is placed in the above-mentioned container component and irradiated with light, or one that actuates an irradiation switch when the lid to the container component is closed.

When a photocatalyst is irradiated with light it produces electrons and holes, which react with oxygen to produce active oxygen. Active oxygen has a powerful oxidation force, and decomposes nearly all organic matter into carbon dioxide and water. This light usually has a wavelength of 380 nm or lower. With the cleansing system of the present invention, if the irradiating light has a wavelength of 200 to 800 nm at the optical emission component, if light with a wavelength of 430 to 800 nm accounts for no more than 70% with respect to the above wavelength range, and if energy at 380 nm and lower is at least 10 mW/cm ², then the cleansing action produced at a wavelength of 380 nm or lower can be utilized to reduce the proportion of light of 430 nm or more, which is a cause of heat generation, and the cleansing time can be controlled with the irradiation energy of at least 10 mW/cm².

Also, apatite is able to adsorb substances, and is particularly adept at adsorbing bacteria, viruses, odors, and other such components. Therefore, the use of titanium dioxide covered with apatite makes it possible to create an environment in which the titanium dioxide decomposes these components, so the cleansing effect is better than when titanium dioxide alone is used. Also, when titanium dioxide adheres to the article being cleansed and is then exposed to light, the article itself may sometimes decompose, but this problem is avoided if the titanium dioxide is covered with apatite.

The present invention is characterized in that the oxidation and reduction action produced mainly by photoactivity is utilized to achieve a better bleaching effect on discolored teeth. “Discolored teeth” as used in the present invention is defined in a broad sense that encompasses coloration. The chemicals and devices used with the present invention are basically just apatite or another compound of phosphorus and calcium, hydrogen peroxide (preferably 4% or less), one or more kinds of acid such as phosphoric acid and pyrophosphoric acid, and a light source (irradiation device), but the safety, ease of operation, and bleaching effect thereof are pronounced.

The bleaching agent of the present invention comprises a compound of phosphorus and calcium in one preferred embodiment. Amorphous apatite, calcium phosphate, or a substance whose main component is calcium phosphate, with a particle size of about 1 nm to 10 μm, can be used favorably as the compound of phosphorus and calcium here, but this compound is not limited to these. As long as the effect is the same, that is, as long as it is a compound of phosphorus and calcium that produces photoactivity, the form and properties thereof are not important. A smaller particle size is preferable here because the activity will be higher, which means that a smaller amount need be applied, the amount used an be reduced, and since the coating film can be thinner, for example, a good bleaching effect can be obtained in a short time, among other advantages.

The compound composed of phosphorus and calcium pertaining to the present invention will now be described through preferred embodiments thereof, but the present invention is not limited to or by the following embodiments. With the present invention, as will be shown in specific terms in the examples given below, the photoactivity can be measured and the numerical value thereof used as an index to quantify the level of bleaching.

If this photoactivity is at least 0.1, stains of teeth F1 to F2 can be decomposed, and the product can be utilized as a bleaching agent. The photoactivity is preferably at least 0.2, in which case teeth of F3 and lower can be bleached, while at least 0.3 is better yet, in which case nearly all organic chemical substances can be adsorbed or decomposed.

The weight ratios of the above components can be suitably varied and adjusted according to whether the degree of discoloration is mild or severe, which allows products suited to each patient to be made available. The bleaching agent of the present invention is usually used in the form of a uniform transparent solution or a paste by mixing, kneading, and dispersing the compound of phosphorus and calcium in water, but other possibilities also exist, and any product prepared in a similar fashion is included in the scope of the present invention. There are no particular restrictions here on the means and apparatus used for preparing the bleaching agent, such as the mixing, kneading, and dispersing of the above components, the means for causing the bleaching agent to adhere, and so forth, and can all be selected as appropriate. One favorable example of how the bleaching agent can be made to adhere to the tooth surface is a method in which the tooth surface is directly coated with the bleaching agent, but other methods can also be used, and should be selected as appropriate. Here, the bleaching agent of the present invention, that is, a substance containing a compound of phosphorus and calcium having photoactivity, may be used to impregnate cloth, paper, glass cloth, ceramic paper, organic gel, inorganic gel, or the like, which is then made to adhere to the tooth surface and irradiated with light. In addition, the above-mentioned bleaching agent may be supported on a suitable carrier, which is then made to adhere to a tooth or a row of teeth, for example. Thus, the most appropriate method and means can be selected.

The bleaching agent of the present invention is characterized in that the above two components are used together as the active components, and can be used, for example, in the form of a solution or paste containing these components, or can be used in a form that suitably combines these components as separate entities, so there are no particular restrictions on the form thereof. The bleaching of discolored teeth with the above-mentioned bleaching agent can be accomplished, for example, by coating the surface of the teeth with a solution or paste of a compound of phosphorus and calcium having photoactivity, irradiating with light, and repeating this procedure a number of times. How many times the coating and optical irradiation are repeated should be appropriately adjusted as dictated by the severity of the discoloration, and there are no particular restrictions thereon. The operation involving coating with or otherwise applying the above-mentioned solution or paste usually involves applying fresh solution or paste about every 1 to 20 minutes, and the interval and frequency thereof should be appropriately set according to the condition of the teeth. The bleaching agent of the present invention is effective at bleaching both medullated and nonmedullated teeth, and has an outstanding effect in terms of bleaching teeth safely and easily. The above-mentioned bleaching agent need not comprise just a compound of phosphorus and calcium, and one or more of a low concentration (4% or less) of hydrogen peroxide and/or an acid such as phosphoric acid or pyrophosphoric acid can also be compounded.

The compound of phosphorus and calcium is preferably composed of at least one of octacalcium phosphate, tricalcium phosphate, or the like or apatite having Ca ₉(PO₄)₆in its structure, and it is particularly favorable for the apatite to be hydroxyapatite or fluoroapatite because these have excellent biocompatibility and high photoactivity. Further, these apatites usually contain elemental calcium, but some of this may be substituted with iron, chromium, magnesium, zirconium, aluminum, or the like.

A compound of phosphorus and calcium conforms well to the enamel of the teeth, and therefore bleaches more effectively than other materials. Specifically, when the surface of the teeth is coated with this compound, the powder is readily adsorbed to the enamel, so sufficient bleaching can be achieved even though the photoactivity is not all that high. Also, because of this, when hydrogen peroxide is used in a high concentration that promotes the recalcification, etc., of enamel, the enamel may be damaged through decalcification, resulting in a loss of surface gloss, and recurrence is more likely.

It is preferable for the particle size of the compound of phosphorus and calcium to be small because the activity will be higher and biocompatibility superior. Accordingly, it is preferable to employ a production method that will yield a finer compound of phosphorus and calcium. Particularly favorable is a compound of phosphorus and calcium produced in a simulated body fluid. The compound of phosphorus and calcium produced by this method will have a small particle size and a large surface area, and will therefore have extremely good photoactivity and biocompatibility.

Ideally, this apatite is manufactured by being precipitated in a simulated body fluid. Naturally, other standard manufacturing methods can also be employed; for instance, a wet process, wet heat process, or mechanochemical process, can be used, or the apatite can be taken from natural coral or the bones of animals.

A simulated body fluid is prepared by dissolving NaCl, NaHCO ₃, KCl, K₂HPO₄.3H₂O, MgCl₂.6H₂O, or CaCl₂and Na₂SO₄, NaF, FeSO₄, FeCl₃, or the like in water. It is preferable to adjust the pH to between 7 and 8 with HCl, (CH₂OH)₃CNH₂, or the like. Adjusting the pH to 7.4 is particularly favorable.

The composition of the simulated body fluid used in the present invention preferably comprises 120 to 1000 mM Na ⁺, 1 to 200 mM K⁺, 0.5 to 100 mM Ca²⁺, 0.5 to 50 mM Mg²⁺, 80 to 2000 mM Cl⁻, 0.5 to 300 mM HCO³⁻, 1 to 200 mM HPO₄ ²⁻, 0.1 to 200 mM SO₄ ²⁻, 0.5 mM F⁻, and 0.1 to 20 mM of at least one type of metal ion such as Fe, Cr, Zr, or Al. If the concentrations are below these ranges, it will take too long for the compound of phosphorus and calcium to precipitate, but if the concentrations are above these ranges, the compound of phosphorus and calcium will precipitate too suddenly, making it difficult to control the particle size and shape.

The preferred temperature of the simulated body fluid is from 30 to 100° C. If the temperature is lower than this, the compound of phosphorus and calcium will take too long to precipitate, but if the temperature is above this, evaporation of the simulated body fluid will make it impossible to control the particle size and porosity. The ideal temperature is between 30 and 60° C. The duration of the precipitation is preferably from 10 seconds to 18 days. The compound of phosphorus and calcium will not have time to precipitate sufficiently below this range, but the particles will be too large if the time is longer than this.

Photoactivity and shape can be controlled by varying the composition of the simulated body fluid, the temperature, and the duration. If the content of phosphorus or calcium is reduced, the temperature is lowered, or the duration shortened, the resulting compound of phosphorus and calcium will have a smaller particle size. If the content of phosphorus or calcium is increased or the temperature is raised, the resulting compound of phosphorus and calcium will have a larger particle size.

The compound of phosphorus and calcium precipitated in this manner may be either amorphous or crystalline, and may be tricalcium phosphate, octacalcium phosphate, hydroxyapatite, fluoroapatite, chloroapatite, or another such apatite, or any other type of calcium phosphate. A combination of these may also be used.

In actual use, the compound may be filtered or centrifuged and then washed before use, and depending on the application, it may be used directly as it is or concentrated before use.

In one preferred embodiment of the calcium phosphate pertaining to the present invention, this compound can be expressed by the following general formula.

The structure includes A ₉(BO₄)₆, and preferably A_x(BO_y)_zX (where A is one or more metal atoms selected from among Ca, Co, Ni, Cu, Al, La, Cr, Fe, Mg, and other such metal atoms, B is a metal atom such as P or S, and X is a hydroxyl group (—OH), a halogen atom (such as F or Cl), or the like). Examples of this calcium phosphate include apatite, hydroxyapatite, fluoroapatite, chloroapatite, tricalcium phosphate, and calcium hydrogenphosphate, although this list is not meant to be comprehensive. Apatites that can be used favorably in the present invention are hydroxyapatite and fluoroapatite in which X in the above formula is a hydroxyl group or a fluorine atom. It is preferable to use an apatite in which X in the formula is a hydroxyl group and A is calcium (Ca). Some of the A groups may be substituted with Co, Ni, Cu, Al, La, Cr, Fe, Mg, or the like.

A material in the form of a sheet or ribbon is preferred because it will offer superior photoactivity and adsorption function. Apatite, for example, is usually shaped like a pencil in the form of a hexagonal column, but a flat shape is particularly favorable. However, since the original shape is that of a hexagonal column, even if the material is manufactured in the form of a flat plate, the particles will attempt to grow in hexagonal form. Therefore, if the particles are produced from the outset in the form of plates, then even a compound of phosphorus and calcium with a less- than-perfect shape that is on the way to becoming a hexagonal columnar shape will function adequately. For instance, the ratio between the thinnest and longest portions should be at least 1.2. Below this, photoactivity will be too low, and 1.5 or higher is preferable.

As discussed above, the particle size of the compound of phosphorus and calcium is preferably small because the activity will be higher and biocompatibility superior, and to this end, it is preferable to produce the compound in a simulated body fluid that will yield a finer compound of phosphorus and calcium. The compound of phosphorus and calcium produced by this method will have a small particle size and a large surface area, and will therefore have extremely good photoactivity and biocompatibility. The apatite pertaining to the present invention and obtained in this manner has good biocompatibility and adsorbs proteins, amino acids, bacteria, viruses, and so forth. The particle size is preferably from 1 nm to 10 μm. Smaller than this, the particles will be difficult to handle, but if they are larger than this their photoactivity and adsorptivity will suffer. The specific surface area is preferably at least 5 m ²/g. Below this, photoactivity and adsorptivity will be poor. An even better range of particle size is from 1 nm to 2 μm. Above 2 μm, it will be difficult to coat the surface of the teeth.

The primary action of the bleaching agent of the present invention is the bleaching action produced by the compound of phosphorus and calcium. When the compound of phosphorus and calcium is irradiated with light it produces electrons and holes, which react with hydrogen peroxide to produce active oxygen. This active oxygen has a far more powerful oxidation force than ozone, and oxidizes and decomposes nearly all organic matter all the way down to carbon dioxide. Furthermore, when the bleaching agent is used as an aqueous solution of 4% hydrogen peroxide, active oxygen having a powerful oxidation force can be easily produced by irradiation with light, and the result is a synergistic effect that combines the oxidative action of the 4% aqueous hydrogen peroxide itself to effectively increase charge separation, electron-hole mobility, reactivity with protons or hydroxyl groups, and so forth as compared to when the bleaching agent is used alone.

Tooth coloration factors are listed below, roughly divided into extrinsic and intrinsic factors.

Extrinsic Coloration Factors

I. Food components (dyes)

Hard water (containing iron, etc.)

Soft drinks (tea, coffee, cocoa, cola, red wine, etc.)

II. Dyes produced by bacteria in the oral cavity

III. Tobacco

IV. Metallic vapor

V. Medications (disinfectants)

Intrinsic Coloration Factors

I. Pulp decay

II. Intrapulpal bleeding (injury, following extirpation of pulp, arsenious acid)

III. Root canal filler components (amalgam, silver powder, iodine, etc.)

IV. Tooth decay, rheumatic fever

V. Metabolic disorders, (congenital) ochronosis, alcaptonuria, congenital erythropoietic porphyria, fetal erythroblastosis, neonatal severe jaundice

VI. Medications (antibiotics, root canal treatment drugs)

VII. Hard water (containing fluorine)

The above coloration factors originate in various kinds of colorants, iron salts, tannic acid, chlorhexidine, benzalkonium chlorhexidine hydrochloride, cyclones sic, and so forth, and these coloring substances are deposited on tooth enamel and dentine. Because of its excellent biocompatibility, a solution of a compound of phosphorus and calcium and 4% or lower aqueous hydrogen peroxide will permeate between the dentine and between the enamel rods of the teeth, so that colored substances are decomposed by the oxidation and reduction action produced by photoactivity, and the teeth are bleached. The bleaching method of the present invention will provide a good bleaching effect on teeth discolored by both the intrinsic and extrinsic factors listed above. The light source (illuminating device) used in the present invention is generally an incandescent lamp, fluorescent lamp, halogen lamp, xenon lamp, mercury vapor lamp, UV lamp, or the like, but from the standpoints of safety, simplicity, and bleaching effect, particularly favorable examples include LEDs (light emitting diodes) and semiconductor laser lamps (penlights). In terms of generating active oxygen through photoactivity and the oxidation action thereof, the irradiating light preferably includes a large proportion of short-wavelength light, which has greater energy, such as ultraviolet rays. Ultraviolet rays, though, are harmful in that they can cause cancer and inflammation in humans, so visible light is preferable from the standpoint of safety, and purple light is especially good because of its greater energy. In the present invention, a tooth bleaching system (kit) can comprise the above-mentioned bleaching agent, mans for applying this bleaching agent (such as a coating device), an irradiation device, other medications, other dental treatment materials, devices, and so forth in a suitable combination.

The present invention is also a composition for environmental purification composed of a photoactive compound of phosphorus and calcium, wherein the degree of photoactivity is at least 2, and preferably at least 5, and even more preferably at least 8, and which is precipitated in a simulated body fluid in which calcium phosphate clusters are present, and is also a composition for environmental purification containing a compound of phosphorus and calcium in the form of a plate or ribbon. The present invention is also a powder or thin film of the above for coating an article, or is a paint containing one of these, or is a building material, artificial plant, food container, or other such article coated with one of these. The photoactive compound of phosphorus and calcium pertaining to the present invention will now be described through preferred embodiments thereof, but the present invention is not limited to or by these embodiments.

With the present invention, as will be shown in specific terms in the examples given below, the degree of photoactivity can be measured and the numerical value thereof used as an index to quantify photoactivity.

If the photoactivity is at least 0.005, it will be possible to adsorb or decompose organic chemical substances with a low concentration of 1 ppm or less, such as colorants, nitrogen oxides, or aldehydes, or bacteria and viruses in the air or water, allowing the product to be utilized as an environment cleaning material. Preferably, if the photoactivity is at least 0.02, organic chemical substances with a concentration of 0.2 ppm or less can be adsorbed or decomposed, and if the photoactivity is at least 0.2, then nearly all organic chemical substances can be adsorbed or decomposed.

Next, with the present invention, as shown in the examples given below, the degree of photo-oxidation can be measured and the numerical value thereof used as an index to quantify photoactivity.

If the photo-oxidation is at least 2, it will be possible to adsorb or decompose organic chemical substances with a low concentration of 1 ppm or less, such as colorants, nitrogen oxides, or aldehydes, or bacteria and viruses in the air or water, allowing the product to be utilized as an environment cleaning material. Preferably, if the photo-oxidation is at least 5, organic chemical substances with a concentration of 2 ppm or less can be adsorbed or decomposed, and if the photo-oxidation is at least 8, then nearly all organic chemical substances can be adsorbed or decomposed.

An apatite such as this is preferably manufactured by being precipitated in a simulated body fluid in which calcium phosphate clusters are present. Naturally, other standard manufacturing methods can also be employed. For instance, a wet process, wet heat process, or mechanochemical process, can be used, or the apatite can be taken from natural coral or the bones of animals. A simulated body fluid is prepared by dissolving NaCl, NaHCO ₃, KCl, K₂HPO₄.3H₂O, MgCl₂.6H₂O, or CaCl₂and Na₂SO₄, NaF, FeSO₄, FeCl₃, or the like in water. It is preferable to adjust the pH to between 7 and 8 with HCl, (CH₂OH)₃CNH₂, or the like. Adjusting the pH to 7.4 is particularly favorable.

The composition of the simulated body fluid used in the present invention preferably comprises 120 to 1000 mM Na ⁺, 1 to 200 mM K⁺, 0.5 to 100 mM Ca²⁺, 0.5 to 50 mM Mg²⁺, 80 to 2000 mM Cl⁻, 0.5 to 300 mM HCO₃ ⁻, 1 to 200 mM HPO₄ ²⁻, 0.1 to 200 mM SO₄ ²⁻, 0.5 mM F⁻, and 0.1 to 20 mM of at least one type of metal ion such as Fe, Cr, Zr, or Al. With this composition, calcium phosphate clusters (Ca₉(PO₄)₆) will be present in the solution, and these clusters will group together and produce a compound of phosphorus and calcium. If the concentrations are below these ranges, it will take too long for the compound of phosphorus and calcium to precipitate, but if the concentrations are above these ranges, the compound of phosphorus and calcium will precipitate too suddenly, making it difficult to control the particle size and shape.

The preferred temperature of the simulated body fluid is from 30 to 100° C. If the temperature is lower than this, the compound of phosphorus and calcium will take too long to precipitate, but if the temperature is above this, evaporation of the simulated body fluid will make it impossible to control the particle size and porosity. The ideal temperature is between 30 and 60° C. The duration of the precipitation is preferably from 1 minute to 18 days. The compound of phosphorus and calcium will not have time to precipitate sufficiently below this range, but the particles will be too large if the time is longer than this.

Photoactivity, shape, and particle size can be controlled by varying the composition of the simulated body fluid, the temperature, and the duration. If the content of phosphorus or calcium is reduced, the temperature is lowered, or the duration shortened, the resulting compound of phosphorus and calcium will have a smaller particle size. If the content of phosphorus or calcium is increased or the temperature is raised, the resulting compound of phosphorus and calcium will have a larger particle size. Photoactivity is greater with a compound whose particle size is smaller and specific surface area is greater.

A _x(BO_y)_zX (where A is one or more metal atoms selected from among Ca, Co, Ni, Cu, Al, La, Cr, Fe, Mg, and other such metal atoms, B is an atom such as P or S, and X is a hydroxyl group (—OH), a halogen atom (such as F or Cl), or the like). Examples of this calcium phosphate include apatite, hydroxyapatite, fluoroapatite, chloroapatite, tricalcium phosphate, and calcium hydrogenphosphate, although this list is not meant to be comprehensive. Apatites that can be used favorably in the present invention are hydroxyapatite and fluoroapatite in which X in the above formula is a hydroxyl group or a fluorine atom. It is preferable to use an apatite in which X in the formula is a hydroxyl group and A is calcium (Ca). Some of the A groups may be substituted with Co, Ni, Cu, Al, La, Cr, Fe, Mg, or the like.

A material in the form of a sheet or ribbon is preferred because it will offer superior photoactivity and adsorption function. Apatite, for example, is usually shaped like a pencil in the form of a hexagonal column, but a flat shape is particularly favorable. However, since the original shape is that of a hexagonal column, even if the material is manufactured in the form of a flat plate, the particles will attempt to grow in hexagonal form. Therefore, if the particles are produced from the outset in the form of plates, then even a compound of phosphorus and calcium with a less-than-perfect shape that is on the way to becoming a hexagonal columnar shape will function adequately. For instance, the ratio between the thinnest and longest portions should be at least 1.2. Below this, photoactivity will be too low, and 1.5 or higher is preferable.

The particle size of the compound of phosphorus and calcium is preferably small because the activity will be higher and biocompatibility superior, and to this end, it is preferable to produce the compound in a simulated body fluid that will yield a finer compound of phosphorus and calcium. The compound of phosphorus and calcium produced by this method will have a small particle size and a large surface area, and will therefore have extremely good adsorptivity, photoactivity, and biocompatibility. The apatite pertaining to the present invention and obtained in this manner has good biocompatibility and adsorbs proteins, amino acids, bacteria, viruses, and so forth. The particle size is preferably from 1 nm to 10 μm. Smaller than this, the particles will be difficult to handle, but if they are larger than this their photoactivity and adsorptivity will suffer. The specific surface area is preferably at least 5 m ²/g. Below this, photoactivity and adsorptivity will be poor.

A compound of phosphorus and calcium manufactured in this manner can be made into a composition for environmental purification containing this compound, or a paint containing this compound, and used to kill bacteria and mold, remove odors, prevent staining, purify water or the atmosphere, and so on. For example, the above-mentioned paint can be applied to polyethylene or other such disposable food containers and trays, reusable tableware and food storage containers, and kitchen utensils, and the effect will be that bacteria, mold, and odors will be eliminated from these coated articles. A binder here may be either organic or inorganic, and the above-mentioned paint may also be mixed into a conventional paint. In particular, because calcium phosphate is excellent at adsorbing bacteria and proteins, and is safe and harmless, it can be used by being applied to food containers and artificial plants. Accordingly, a powder may be applied directly, or as a paint mixture containing an organic or inorganic binder. The mixture may also include a resin, paper, tile, ceramic, or the like.

The present invention is also a composition for environmental purification containing a photoactivity compound of phosphorus and calcium, characterized by being precipitated in a simulated body fluid in which calcium phosphate clusters are present. The above-mentioned compound preferably has a particle size of 1 nm to 10 μm and a specific surface area of at least 5 m ²/g, has a degree of photoactivity of at least 0.02, has a degree of photo-oxidation of at least 2, and has good adsorptivity, photoactivity, and biocompatibility. As a result, this compound can be used to kill bacteria and mold, remove odors, prevent staining, and purify water or the atmosphere.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the cleansing system of the present invention. [0171]
Key: [0172]

1 container component

2 irradiation component

3 lamp

4 lid component

5 dental prosthetic

6 cleansing agent solution

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in specific terms through examples, but the present invention is in now way limited by these examples. [0173]

EXAMPLES A

Example 1

0.1 g of titanium dioxide powder with a particle size of about 50 nm was mixed under ultrasonic vibration with 5 g of phosphoric acid and 10 g of pyrophosphoric acid to obtain a mixed paste. [0174]
This was stored for 2 hours, and then water was added to bring the total up to 500 mL. The pH was 2. Stained dentures were placed in this aqueous solution and irradiated with light from a 500 W xenon lamp. 6 hours later the dentures were taken out and examined, which revealed that the stubborn tartar that had been adhering to the dentures had been completely removed. [0175]

Example 2

0.4 g of a sol solution containing 22% titanium dioxide with a particle size of about 6 nm was mixed under ultrasonic vibration with 3 g of phosphoric acid and 10 g of pyrophosphoric acid to obtain a mixed paste. [0176]
This was stored for 10 hours, and then water was added to bring the total up to 500 mL. The pH was 1. Stained dentures were placed in this aqueous solution and irradiated with sunlight. 6 hours later the dentures were taken out and examined, which revealed that the nicotine and odor that had been adhering to the dentures had been completely removed. [0177]

Example 3

0.5 g of a sol containing 30% titanium dioxide with a particle size of about 5 nm was mixed under ultrasonic vibration with 10 g of phosphoric acid and 30 g of pyrophosphoric acid to obtain a mixed paste. [0178]
This was stored for 2 hours, and then water was added to bring the total up to 500 mL. The pH was 1. Stained dentures were placed in this aqueous solution and irradiated with light from a 60 W halogen lamp. 2 hours later the dentures were taken out and examined, which revealed that the stubborn tartar, odor, and nicotine that had been adhering to the dentures had been completely removed. [0179]

Example 4

0.1 g of apatite-covered titanium dioxide powder with a particle size of about 50 nm was mixed under ultrasonic vibration with 5 g of phosphoric acid and 10 g of pyrophosphoric acid to obtain a mixed paste. The apatite covering was applied by soaking the titanium dioxide for 1 hour at 40° C. in a simulated body fluid containing phosphoric acid ions and calcium ions. The coverage was 1%. [0180]
This product was stored for 2 hours, and then water was added to bring the total up to 500 mL. The pH was 2. Stained dentures were placed in this aqueous solution and irradiated with light from an LED lamp. 6 hours later the dentures were taken out and examined, which revealed that the odor that had been adhering to the dentures had been completely removed. With this example, odor was completely removed, and no odor whatsoever was generated when the resin part of the dentures was shaved down. [0181]

Example 5

0.1 g of a sol solution containing 50% titanium dioxide with a particle size of about 3 nm was mixed under ultrasonic vibration with 5 g of phosphoric acid and 10 g of pyrophosphoric acid to obtain a mixed paste. [0182]
This was stored for 10 hours, and then water was added to bring the total up to 500 mL. The pH was 1. Stained dentures were placed in this aqueous solution and irradiated with sunlight. 6 hours later the dentures were taken out and examined, which revealed that the nicotine stains that had been adhering to the dentures had been completely removed. [0183]

Comparative Example 1 (Cleaning with a Brush)

Tartar adhering to dentures was scrubbed with a denture brush, but almost none could be removed, nor could the odor be removed. [0184]

Comparative Example 2

A commercially available enzyme type of denture cleansing agent was used according to the included instructions. Specifically, 300 cc of 40° C. hot water was put in a cup, into which one table was dropped. The tablet was dissolved and the dentures immersed. They were taken out and washed after 5 minutes, but none of the staining caused by tartar or nicotine had been removed. Most of the odor remained as well. Simple detritus, however, was successfully removed. [0185]

Example 6

The cleansing agent of the present invention was manufactured by mixing and dissolving a 1 wt % titanium dioxide sol (25%), 1 wt % phosphoric acid, and 2 wt % pyrophosphoric acid in water. This cleansing agent was placed in a container, sealed, and stored at room temperature for 2 months, during which time no precipitation or the like occurred. [0186]
Meanwhile, a silver sheet with a purity of 99.99% was left for 20 months in the air, during which time its surface tarnished black and a film of silver sulfide was formed. This silver sheet was soaked in the above-mentioned cleansing agent and left in sunlight, whereupon the surface returned to its original silvery gloss in approximately 120 minutes. No odor was generated during the soaking of the silver sheet, nor did any odor remain on the silver sheet after its cleansing. [0187]

Example 7

The same silver sheet as that in Example 6 above was soaked in a sodium polysulfide aqueous solution comprising sulfur saturated in a 20% sodium sulfide aqueous solution. At the point when the formation of a sulfide film had completely blackened the surface, the silver sheet was lifted out and rinsed with water. [0188]
This silver sheet was soaked in the same cleansing agent as in Example 6, whereupon the surface returned to its original silvery gloss in approximately 120 minutes. No odor was generated during the soaking of the silver sheet, nor did any odor remain on the silver sheet after its cleansing. [0189]

Example 8

The cleansing agent of the present invention was manufactured by mixing and dissolving a 1 wt % titanium dioxide sol (25%), 1 wt % phosphoric acid, and 2 wt % pyrophosphoric acid in water. [0190]
A cloth to which adhered perspiration odor and tobacco odor was soaked in this cleansing agent for 1 hour, which completely eliminated any odor from the cloth. [0191]
Reference Example (Manufacture of Photocatalyst Partially Covered with a Compound Composed of at Least One Ca[0192] ₉(PO₄)₆Unit)
10 g of anatase titanium oxide (Super Titania, average particle size of 30 nm, made by Showa Denko) was suspended in 1 liter of simulated body fluid, allowed to stand for 2 hours at 37° C., and then dried at 100° C. The simulated body fluid consisted of 8000 mg of sodium chloride, 200 mg of potassium chloride, 1150 mg of sodium hydrogenphosphate, 200 mg of potassium hydrogenphosphate, and 200 mg of calcium chloride in 1 liter of water. This yielded a photocatalyst in which part of the surface (approximately 2% according to electron microscopy) of titanium oxide particles was covered with a compound composed of at least one Ca[0193] ₉(PO₄)₆unit.

Example 9

The TiO[0194] ₂obtained in the Reference Example, which was partially covered with a compound composed of at least one Ca₉(PO₄)₆unit, was dissolved in water in an amount of 0.1 wt % along with 20% phosphoric acid and 10% pyrophosphoric acid to produce an aqueous solution. This cleansing agent was subjected to the following antibacterial test.
Staphylococcus aureus KPI S-96 and O-157 entero-hemorrhagic [0195] Escherichia coli KPI S-95 that had each been separately stored in its own place were used. In this use, 5 mL of brain heart infusion broth (BHI, Difco) was inoculated with one platinum loop of bacteria on a preservation medium, and cultivation was performed twice, for 4 hours each time, at 37° C. 0.5 mL of this culture broth was used to inoculate 5 mL of fresh BHI, and this was cultivated for 18 hours at 37° C., the product of which was diluted with PBS to adjust the concentration to 1.2×105 CFU/mL O-157 and 1.2×10⁵CFU/mL Staphylococcus aureus, and then subjected to testing.
The test cloth was produced by cutting a JIS dye fastness cotton test cloth into pieces measuring 5×5 cm, and sterilizing these for 15 minutes in a 121° C. autoclave. [0196]
0.1 mL of a dilute bacterial suspension was applied to the test cloth by pipette, and the cloth was soaked in the cleansing system solution for 12 minutes, after which any bacteria adhering to the sample were dispersed in 30 mL of 100 mL of PBS, the viable bacteria count was measured by pour culture method, and the survival rate was calculated. An ordinary agar medium was used for the pour culture. [0197]
No live bacteria of either O-157 or Staphylococcus aureus could be recovered from the test cloth. [0198]

Examples B

Example

(1) Preparation of Cleansing Agent Solution [0199]
A cleansing agent solution was prepared from the following components. [0200]
0.05% titanium dioxide and apatite-covered titanium dioxide (sol solution) [0201]
1% phosphoric acid [0202]
2% sodium pyrophosphate [0203]
water [0204]
(2) Apparatus [0205]
FIG. 1 shows the apparatus used in these examples. [0206]
This apparatus comprised a container component for holding a dental prosthetic, an irradiation component having the function of irradiating the dental prosthetic with the light of a light source (lamp) from a light emission component, a filter for selecting the wavelength, a lid component, and an operating switch for actuating an irradiation switch only when the lid is closed. A halogen lamp, metal halide lamp, black light lamp, and LED were used as the light sources. [0207]
(3) Cleansing Method [0208]
300 mL of the cleansing agent solution was put in the container component, and stained dentures were immersed in the solution. This was then irradiated with light from above. [0209]
(4) Results [0210]
Table 1 shows the results. In Table 1, the units of “Energy of 380 nm or lower” are mW/cm[0211] ². “Effect” indicates the extent of the cleansing effect. “Temperature over 60° C.” indicates the temperature range of the article being cleansed.
At an energy of 380 nm or lower (units: mW/cm[0212] ²), there was a cleansing effect at 10 mW/cm²and above.
As for 430-800/200-800 nm (units: %), when the proportion of light of 430 to 800 nm reached 80%, the temperature went over 60° C. and a slight deformation in the resin was noted. [0213]

When a combined evaluation was made, it was found that a good cleansing effect was obtained when the proportion of light with a wavelength of 430 to 800 nm with respect to light with a wavelength of 200 to 800 nm was 70% or lower and the energy of 380 nm or lower was at least 10 mW/cm ², whereas a good effect was not obtained when the energy of 380 nm or lower was less than 10 mW/cm²or when the proportion of light with a wavelength of 430 to 800 nm was 80%.

TABLE 1


		Energy of
	Light	380 nm or			Temperature
Apparatus
1	source	lower	Effect	430-800/200-800 nm	over 60° C.	Evaluation

2	halogen	40	**	80	over	poor
3	halogen	45	**	60	under	good
4	metal	70	***	30	under	good
	halide

5	metal	75	***	20	under	good
	halide

6	black light	20	**	40	under	good
7	black light	20	**	20	under	good
8	LED	2	*	5	under	poor
9	LED	10	***	5	under	good
10						good

Example C

Example

(1) Measurement of Photoactivity [0215]
The degree of photoactivity was measured as follows. In a test of colorant removal, glossy paper stained with hematoporphyrin was coated with apatite and irradiated with light, and the change in color was measured. [0216]
The stained paper was the back side of an Epson Superfine ink jet printer-use special glossy film, the hematoporphyrin was Sigma H-5518, and the ethanol was a guaranteed reagent. The film was immersed in a 0.1% hematoporphyrin ethanol solution (0.1 g/100 mL), then cut to a size of 9×50 mm to obtain a sample. A halogen lamp light source apparatus (made by Ushio Denki) was used for the optical irradiation (light source apparatus: model JCR12V-100WC, wavelength 380 to 460 nm, power 100 W, irradiation energy 204 mW/cm[0217] ²at the above-mentioned wavelength). An OFC-300A (made by Nippon Denshoku) was used as a color-difference meter. The paper was coated by pouring 40 mg of a 0.06% aqueous solution of apatite onto the paper, then placed 3 mm from the tip of the optical cable of the irradiation apparatus and irradiated with light for one minute. The test piece was washed with distilled water, after which the water was thoroughly wiped away and a measurement was made with the color-difference meter. This procedure was repeated 5 times. The L* value was 61 prior to the test.
The degree of photoactivity was defined as (L* value after test)−(L* value before test)/(L* value before test). [0218]
(2) Preparation of Bleaching Agent [0219]
A synthesized compound of phosphorus and calcium was combined as shown in Table 2 with water and hydrogen peroxide, then kneaded and dispersed to prepare a solution. Compounds of phosphorus and [0220] calcium 1 to 4 are given as 1 to 4 in Table 3.
A simulated body fluid was prepared by using NaCl, NaHCO[0221] ₃, KCl, K₂HPO₄.3H₂O, MgCl₂.6H₂O, CaCl₂, and Na₂SO₄or NaF, FeSO₄, FeCl₃, or the like and distilled water; an aqueous solution with a pH of 7.4 was prepared from the components in Table 3, and allowed to stand.
(3) Production of Tooth Bleaching System [0222]
A tooth bleaching system (kit) was produced by combining the above-mentioned bleaching agent, a coating device, an irradiation device (using the purple light of a metal halide lamp), and a pretreatment device in a container. [0223]
(4) Bleaching of Discolored Teeth [0224]
Discolored teeth were bleached by the following procedure using the above-mentioned bleaching agent. [0225]
1) As pretreatment, detritus, tartar, tar, and so forth were removed with an ultrasonic scaler. [0226]
2) The surface of the teeth was cleaned with a rubber cup and then dried, by a standard method. [0227]
3) A simple moisture protection treatment was performed. [0228]
4) The surface of the teeth was coated with each solution and irradiated with visible light. [0229]
5) With each iteration lasting 1 minute, the above-mentioned coating with solution and optical irradiation were repeated 5 times, once every minute. [0230]
(5) Results [0231]

Table 2 shows the effect produced by the above bleaching agent. As is clear from Table 2, a pronounced bleaching effect and antibacterial effect were obtained by performing the above procedure about one time for moderate discoloration (F1), about two or three times for medium discoloration (F2 to F3), or about four or five times for severe discoloration (F4). The above-mentioned bleaching effect was very long-lasting, with no recurrence. Also, the bleaching agent of the present invention provides a pronounced bleaching effect and antibacterial effect through a synergistic effect with the bleaching action of calcium phosphate, so none of the various limitations are imposed on work as in the past with highly toxic 30 to 35% aqueous hydrogen peroxide, and furthermore, since safety is excellent, it was found that this agent can be used for both medullated teeth and nonmedullated teeth. Also, the bleaching effect of the bleaching agent of the present invention was such that a bleaching effect of about four times or better, in terms of oxidation energy, could be obtained in a short time as compared to conventional bleaching agents whose main ingredient was titanium dioxide or aqueous hydrogen peroxide. Furthermore, as can be seen from Table 2, the bleaching tended to take longer as the concentration of aqueous hydrogen peroxide decreased.

TABLE 2


	Compound		Phosphoric
	Of P And	Hydrogen	acid/pyrophosphoric	Discolored			Surface of
Example	Ca	peroxide	acid	teeth	Effect	Recurrence	enamel	Photoactivity

1	1	0	0/0	F1	+++	none	glossy	0.1
2	1	3.5%	0/0	F2	+++	none	glossy	0.3
3	1	3.5%	1%/2%	F2	+++	none	glossy	0.35
4	1	3.5%		F4	++	none	glossy	0.15
5	2	0	0	F3	+++	none	glossy	0.2
6	2	3.5%	0	F4	+++	none	glossy	0.5
7	3	0		F4	++	none	glossy	0.2
8	3	3.5%		F4	+++	none	glossy	0.5
9	4	0		F4	++	none	glossy	0.16
10	4	3.5%		F4	+++	none	glossy	0.5

Comp. 1	0	31%		F1	+ (60 minutes)	no gloss	0.05

TABLE 3


												Precipitates/
	Na⁺	K⁺	Ca²⁺	Mg²⁺	Cl⁻	HCO₃ ⁻	HPO₄ ²⁻	SO₄ ²⁻	F⁻	Metal	Temp/time [min]	particle size

1	71	2.5	2.5	0	70	2	0.5	0.2	0	0	40/300	amorphous/1
2	71	2.5	2.5	1.5	70	2	0.5	0.2	5	0	40/60	apatite/2
3	71	2.5	2.5	1.5	70	2	0.5	0.2	0	Fe, 5	40/120	amorphous/100 nm
4	740	25	1.3	0	750	10	2.5	2.5	0	0	40/3	amorphous/50 nm

The degree of discoloration was classified as follows. [0234]
F1: Entire tooth crown was evenly colored pale yellow, brown, or gray, with no stripes seen. [0235]
F2: Entire tooth crown was evenly colored more darkly than F1, with no stripes seen. [0236]
F3: Dark gray or bluish gray stripes were included. [0237]
F4: Entire tooth crown was discolored in very dark purple or grayish purple. [0238]
The effect was indicated as follows. [0239]
+++: Pronounced bleaching effect with improved whiteness [0240]
++: Some bleaching effect noted, but coloration (discoloration) remained. [0241]

Examples D

Examples 1 to 17

(1) Photoactivity [0242]
The degree of photoactivity was measured as follows. In a test of colorant removal, glossy paper stained with hematoporphyrin was coated with apatite and irradiated with light, and the change in color was measured. [0243]
The stained paper was the back side of an Epson Superfine ink jet printer-use special glossy film, the hematoporphyrin was Sigma H-5518, and the ethanol was a guaranteed reagent. The film was immersed in a 0.1% hematoporphyrin ethanol solution (0.1 g/100 mL), then cut to a size of 9×50 mm to obtain a sample. A halogen lamp light source apparatus (made by Ushio Denki) was used for the optical irradiation (light source apparatus: model JCR12V-100 WC, wavelength 380 to 460 nm, power 100 W, irradiation energy 204 mW/cm[0244] ²at the above-mentioned wavelength). An OFC-300A (made by Nippon Denshoku) was used as a color-difference meter. The paper was coated by pouring 40 mg of a 0.06% aqueous solution of apatite onto the paper, then placed 3 mm from the tip of the optical cable of the irradiation apparatus and irradiated with light for one minute. The test piece was washed with distilled water, after which the water was thoroughly wiped away and a measurement was made with the color-difference meter. This procedure was repeated 5 times. The L* value was 61 prior to the test.
The degree of photoactivity was defined as (L* value after test)−(L* value before test)/(L* value before test). [0245]
(2) Photo-oxidation [0246]
The degree of photo-oxidation was measured as follows. Referring to Masuo and Kato, Journal of Industrial Chemistry [Kogyo Kagaku Zasshi], 1960, No. 5, pp. 748-751, 20 mL of tetralin and 0.02 g of a compound composed of phosphorus and calcium were sealed in a heat-resistant glass reaction vessel with a volume of 100 mL, the reaction temperature was kept constant under an oxygen atmosphere, the system was irradiated with ultraviolet light, and the oxygen absorption rate resulting from the liquid phase oxidation-reaction of the tetralin was found. Specifically, the pressure was read from a differential pressure gauge at specific time intervals within the reactor, and the pressure change (mm H[0247] ₂O/minute) was termed the oxygen absorption rate and used as an index of photo-oxidation.
(3) Preparation of Compound of Phosphorus and Calcium [0248]
A simulated body fluid was prepared by using NaCl, NaHCO[0249] ₃, KCl, K₂HPO₄.3H₂O, MgCl₂.6H₂O, CaCl₂, and Na₂SO₄or NaF, FeSO₄, FeCl₃, or the like and distilled water; an aqueous solution with a pH of 7.4 was prepared from the components given for Examples 1 to 17 in Table 4, and allowed to stand.
In Table 4, [0250] compositions 1 to 9 of the simulated body fluid were as indicated by 1 to 9 in Table 5.
For comparison, commercially available hydroxyapatite made by Wako was used. This apatite has relatively good crystallinity, and its shape is spherical. [0251]

As a result, as shown in Table 4, it was found that the apatite produced using the simulated body fluid exhibited far better photocatalytic activity than the commercially available product.

TABLE 4


				Degree	Degree
			Particle	of	of
	Simulated	Temp/	size/shape (aspect	photo-	photo-
Exam-	body	time	ratio)/specific	oxida-	ac-
ple	fluid	(min)	surface area	tion	tivity

1	1	40/60	2/sheet 3/10	6	0.15
2	1	40/180	10/sheet 6/2	2	0.03
3	1	60/10	5/sheet 3/2	2	0.03
4	1	30/300	20 nm/sheet 10/50	5	0.15
5	2	35/60	50 nm/sheet 5/100	8	0.5
6	2	35/180	100 nm/sheet 15/50	7	0.19
7	2	60/10	1/sheet 5/20	3	0.03
8	2	30/300	20 nm/sheet 23/35	6	0.18
9	3	40/60	2/sheet 10/10	5	0.13
10	3	40/180	5/sheet 20/10	4	0.04
11	3	60/10	2/sheet 10/10	4	0.04
12	4	30/300	20 nm/sheet 5/32	10	0.5
13	5	40/60	10 nm/sheet 6/20	9	0.45
14	6	40/60	100 nm/sheet 15/50	9	0.52
15	7	40/60	20 nm/sheet 4/100	8	0.36
16	8	40/180	1/sheet 15/10	6	0.13
17	9	40/1	10 nm/sheet 1.5/100	10	0.50
Comp.			1/granules/2	0	0
1

TABLE 5


	Na⁺	K⁺	Ca²⁺	Mg²⁺	Cl⁻	HCO₃ ⁻	HPO₄ ²⁻	SO₄ ²⁻	F⁻	Metal

1	147	5	2.5	1.5	147	4.2	1	0.5	0	0
2	71	2.5	2.5	0	70	2	0.5	0.2	0	0
3	71	2.5	2.5	1.5	70	2	0.5	0.2	5	0
4	71	2.5	2.5	1.5	70	2	0.5	0.2	0	Fe, 5
5	71	2.5	2.5	1.5	70	2	0.5	0.2	0	Fe, 10
6	71	2.5	2.5	1.5	70	2	0.5	0.2	0	Al, 0.2
7	71	2.5	5	1.5	70	2	0.5	0.2	0	0
8	71	2.5	7	1.5	70	2	0.5	0.2	0	0
9	750	25	1.3	0	750	10	2.5	2.5	0	0

(4) Preparation of Paint [0254]
A paint was prepared by mixing the sample of Example D-12 in Table 4 with water and an organic binder. This paint was then applied to the exterior walls of a building and left for 3 months, at which point there was no soiling whatsoever of the apatite of the present invention. [0255]
This paint was also used to coat a food container, and bread was placed inside and left for one week, at which point mold appeared on the third day with the commercially available product, but not with the apatite of the present invention. [0256]
The following effects are realized with the present invention. [0257]
(1) It is possible to provide a cleansing, bleaching, and sterilizing agent containing titanium dioxide, whose dispersibility is good and with which there is no separation or precipitation of the components. [0258]
(2) The final product can be in concentrated form. [0259]
(3) Better cleansing performance can be achieved through pH control. [0260]
(4) The product readily dissolves before use, making it easier to ship or carry around. [0261]
(5) The product is effective at deodorization. [0262]
(6) It is possible to provide a new type of sterilizing and cleansing agent for cloths, fibers, and metal products. [0263]
(7) Tartar and nicotine which there was no way to remove up to now can be easily removed, which means that the product can be effectively used on dentures. [0264]
(8) Stubborn stains and odors that could not be removed up to now can be removed by a simple process, which is increasingly important in our aging society in which the use of dentures is growing. [0265]
(9) The cleansing effect of titanium dioxide and the like on dental prosthetics can be enhanced by a simple process. [0266]
(10) A good cleansing effect can be obtained in a short time. [0267]
(11) Stains on dental prosthetics can be completely cleansed away without the use of any other cleansing means. [0268]
(12) A good cleansing effect can be obtained without damaging dental prosthetics. [0269]
(13) It is possible to provide a novel bleaching agent for discolored teeth. [0270]
(14) It is possible to bleach both medullated teeth and nonmedullated teeth. [0271]
(15) Bacteria in the oral cavity can be effectively eliminated. [0272]
(16) A bleaching effect can be obtained safely, with a simple operation, and in a short time. [0273]
(17) The product has less of a psychological effect on the patient. [0274]
(18) Color gradation can be controlled. [0275]
(19) It is possible to select the improvement in color desired by the patient. [0276]
(20) It is possible to provide a composition for environmental purification containing a novel photoactive compound of phosphorus and calcium and having much higher activity than an ordinary compound of phosphorus and calcium. [0277]
(21) The above-mentioned composition exhibits adequate photoactivity for an environment cleaning material. [0278]
(22) The above-mentioned composition has good adsorptivity, photoactivity, and biocompatibility. [0279]
(23) The above-mentioned composition has the action of preventing bacteria and mold, odors, and stains, and of cleaning the atmosphere or water. [0280]
(24) The above-mentioned composition is safe and harmless, and can be used by coating various articles such as food containers, artificial plants, and so forth. [0281]
(25) The above-mentioned composition can be used by coating building materials (exterior or interior), vehicles (automobiles, trains), and so forth. [0282]

Claims

What is claimed is:

1. A cleansing.bleaching.sterilizing agent comprising titanium dioxide with a photocatalytic function and an acid typified by phosphoric acid and pyrophosphoric acid.

2. The cleansing.bleaching.sterilizing agent according to claim 1, wherein the agent is a cleansing.bleaching.sterilizing agent for the oral cavity and dental prosthetics, a cleanser for semiconductors and other such electronic components, a cleanser for mechanical parts, a sterilizing cleanser for foods, a sterilizing cleanser for food containers, or a sterilizing cleanser for articles made of cloth, fiber, or metal.

3. The cleansing.bleaching.sterilizing agent according to claim 1, wherein the titanium dioxide is added as a sol solution;

the titanium dioxide content in the sol solution is from 0.01 to 80%;

the particle size of the titanium dioxide is from 0.1 to 70 nm;

the titanium dioxide produces photocatalytic activity upon optical irradiation of rutile, anatase, or the like; and