U.S. patent application number 10/483269 was filed with the patent office on 2004-09-02 for cleansers, cleaning system, bleaching agents and compositions for environmental conservation.
Invention is credited to Hase, Hiroko, Nonami, Toru.
Application Number | 20040171505 10/483269 |
Document ID | / |
Family ID | 27482443 |
Filed Date | 2004-09-02 |
United States Patent
Application |
20040171505 |
Kind Code |
A1 |
Nonami, Toru ; et
al. |
September 2, 2004 |
Cleansers, cleaning system, bleaching agents and compositions for
environmental conservation
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.
Inventors: |
Nonami, Toru; (Aichi,
JP) ; Hase, Hiroko; (Gifu, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
27482443 |
Appl. No.: |
10/483269 |
Filed: |
January 16, 2004 |
PCT Filed: |
July 18, 2002 |
PCT NO: |
PCT/JP02/07324 |
Current U.S.
Class: |
510/302 |
Current CPC
Class: |
A61L 2/186 20130101;
C11D 11/007 20130101; A61Q 11/02 20130101; A61L 9/18 20130101; A61K
8/29 20130101; A61L 9/00 20130101; A01N 59/26 20130101; A61K 8/24
20130101; A61L 2202/17 20130101; C11D 7/08 20130101; C11D 11/0011
20130101; C11D 7/20 20130101; A61L 2/16 20130101; A01N 59/26
20130101; A01N 59/16 20130101; A01N 59/26 20130101; A01N 2300/00
20130101 |
Class at
Publication: |
510/302 |
International
Class: |
D06L 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2001 |
JP |
2001-217803 |
Jul 18, 2001 |
JP |
2001-217849 |
Jul 18, 2001 |
JP |
217855 |
Oct 26, 2001 |
JP |
2001-329439 |
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
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 2. Description of the Related Art
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] The following methods are examples of ways to remove such
stains from dental prosthetics.
[0023] 1) Mechanical Cleaning
[0024] 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.
[0025] 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.
[0026] 2) Ultrasonic Cleaning
[0027] 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.
[0028] 3) Chemical cleaning
[0029] 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:
H.sub.2O.sub.2+OCl - - - O.sub.2+H.sub.2O+Cl.sup.-
[0030] and a neutral type that generates carbon dioxide gas as
follows:
NaHCO.sub.3+H.sup.+ - - - CO.sub.2+H.sub.2O+Na.sup.+.
[0031] 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.
[0032] As for hypochlorous acid, examples of its foaming mechanism
include an alkaline type that generates oxygen gas as follows:
OCl.sup.-+H.sub.2O.sub.2 - - - O.sub.2+H.sub.2O+Cl.sup.-
[0033] and a neutral type that generates carbon dioxide gas as
follows:
NaHCO.sub.3+H.sup.+- - - CO.sub.2+H.sub.2O+Na.sup.+.
[0034] 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.
[0035] 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.
[0036] Enzymes that have been used include digestive enzymes such
as protease, amylase, and lipase, and mutanase, dextranase,
.beta.-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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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).
[0041] 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.
[0042] Examples of these methods are given below.
[0043] There is a bleaching method in which 30% H.sub.2O.sub.2 is
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% H.sub.2O.sub.2 is 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 H.sub.2O.sub.2 replenished about every 5
minutes so that the gauze will not dry out.
[0044] 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.
[0045] In the bleaching of teeth, the bleaching method and
bleaching agent must satisfy the following conditions.
[0046] (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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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).
[0054] 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.
[0055] 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
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] The present invention will now be described in further
detail.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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.degree. C., and it
should be performed while ultrasonic or other vibration is
imparted, which results in better mixing and a more uniform
solution.
[0073] 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.
[0074] Also, with the present invention, metals or cloths can be
cleansed by soaking them in the diluted or undiluted cleansing
agent.
[0075] 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.sub.x(BO.sub.y).sub.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 CO.sub.3, 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,
Ca.sub.9(PO.sub.4).sub.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 Ca.sub.9(PO.sub.4).sub.6 or titanium dioxide will
exhibit a decomposition function, which allows the material to be
deodorized and sterilized.
[0076] 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.
[0077] 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.
[0078] "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.
[0079] With the present invention, an outstanding cleansing effect
can be obtained by using a sol solution of titanium dioxide to
improve dispersibility.
[0080] 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.
[0081] Further, titanium dioxide that has been compounded with
calcium phosphate as discussed below can be used in the present
invention.
[0082] 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.
[0083] The compound composed of at least one
A.sub.x(BO.sub.y).sub.zX unit and having photoactivity
(photo-oxidation function) used in the present invention will now
be described by using as an example Ca.sub.9(PO.sub.4).sub.6 having
photoactivity (photo-oxidation function). This contains at least
one of the above-mentioned Ca.sub.9(PO.sub.4).sub.- 6 as the
minimum unit. The structure may comprise just the
Ca.sub.9(PO.sub.4).sub.6 units 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.
[0084] 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.sub.9(PO.sub.4).sub.6 units 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 Ca.sub.9(PO.sub.4).sub.6 units may be stacked
in a number of layers to form an amorphous or crystalline
phase.
[0085] This compound composed of at least one
Ca.sub.9(PO.sub.4).sub.6 unit and having photoactivity
(photo-oxidation function) is most preferably produced from a
simulated body fluid containing at least phosphorus and calcium.
Specifically, clusters of Ca.sub.9(PO.sub.4).sub.- 6 are 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
Ca.sub.9(PO.sub.4).sub.6 unit is to be bonded is dispersed,
suspended, or immersed in a simulated body fluid, the compound
composed of at least one Ca.sub.9(PO.sub.4).sub.6 unit 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 Ca.sub.9(PO.sub.4).sub.6
units. This compound can be apatite, tricalcium phosphate, or the
like, but basically any such compound can be used. The
Ca.sub.9(PO.sub.4).sub.6 having photoactivity (photo-oxidation
function) is excellent in terms of its adsorption of substances
such as bacteria, viruses, aldehydes, ammonia, and other harmful
substances.
[0086] The size of the compound composed of at least one
Ca.sub.9(PO.sub.4).sub.6 unit is preferably from 0.01 nm or 50
.mu.m. A range of 0.1 nm or 10 .mu.m 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
Ca.sub.9(PO.sub.4).sub.6 unit.
[0087] If nothing is added to the simulated body fluid, the
Ca.sub.9(PO.sub.4).sub.6 clusters will group together and produce
this compound.
[0088] 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.sub.3(PO.sub.4).sub.2). This working fluid is
prepared, for example, by dissolving NaCl, NaHCO.sub.3, KCL,
K.sub.2HPO.sub.4.3H.sub.2O, MgCl.sub.2.6H.sub.2O, or CaCl.sub.2 and
Na.sub.2SO.sub.4, NaF, or the like in water. It is preferable to
adjust the pH to between 7 and 8 with HCl,
(CH.sub.2OH).sub.3CNH.sub.2, or the like. A pH of 7.4 is
particularly favorable. The Ca.sup.2+ 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.
[0089] 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.
[0090] 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.
[0091] "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.
[0092] 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.
[0093] 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.
[0094] 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.
[0095] For example, three of the above can be weighed out and mixed
under agitation at 25.degree. C. or higher, and preferably from 30
to 40.degree. 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.
[0096] The pH of this cleansing agent solution is preferably
between 1 and 7. Outside this range the titanium dioxide may
separate.
[0097] Preferably, the pH of the cleansing agent solution is
between 1 and 4. Outside this range separation may occur during
long-term storage.
[0098] 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.
[0099] 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.
[0100] 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.
[0101] 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.
[0102] 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.
[0103] 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.sup.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.
[0104] 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.
[0105] 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.sup.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.
[0106] 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.
[0107] 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.
[0108] 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.degree. C. are undesirable
for resins and so forth, and may lead to deformation or
discoloration.
[0109] 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 .mu.m, 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.
[0110] 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.
[0111] 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.
[0112] 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.
[0113] 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.sup.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/cm.sup.2.
[0114] 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.
[0115] 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.
[0116] 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 .mu.m, 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.
[0117] 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.
[0118] 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.
[0119] 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.
[0120] 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.
[0121] 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.sub.9(PO.sub.4).sub.6
in 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.
[0122] 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.
[0123] 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.
[0124] 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.
[0125] A simulated body fluid is prepared by dissolving NaCl,
NaHCO.sub.3, KCl, K.sub.2HPO.sub.4.3H.sub.2O, MgCl.sub.2.6H.sub.2O,
or CaCl.sub.2 and Na.sub.2SO.sub.4, NaF, FeSO.sub.4, FeCl.sub.3, or
the like in water. It is preferable to adjust the pH to between 7
and 8 with HCl, (CH.sub.2OH).sub.3CNH.sub.2, or the like. Adjusting
the pH to 7.4 is particularly favorable.
[0126] The composition of the simulated body fluid used in the
present invention preferably comprises 120 to 1000 mM Na.sup.+, 1
to 200 mM K.sup.+, 0.5 to 100 mM Ca.sup.2+, 0.5 to 50 mM Mg.sup.2+,
80 to 2000 mM Cl.sup.-, 0.5 to 300 mM HCO.sup.3-, 1 to 200 mM
HPO.sub.4.sup.2-, 0.1 to 200 mM SO.sub.4.sup.2-, 0.5 mM F.sup.-,
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.
[0127] The preferred temperature of the simulated body fluid is
from 30 to 100.degree. 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.degree. 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.
[0128] 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.
[0129] 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.
[0130] 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.
[0131] In one preferred embodiment of the calcium phosphate
pertaining to the present invention, this compound can be expressed
by the following general formula.
[0132] The structure includes A.sub.9(BO.sub.4).sub.6, and
preferably A.sub.x(BO.sub.y).sub.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.
[0133] 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.
[0134] 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 .mu.m. 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.sup.2/g. Below this, photoactivity
and adsorptivity will be poor. An even better range of particle
size is from 1 nm to 2 .mu.m. Above 2 .mu.m, it will be difficult
to coat the surface of the teeth.
[0135] 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.
[0136] Tooth coloration factors are listed below, roughly divided
into extrinsic and intrinsic factors.
[0137] Extrinsic Coloration Factors
[0138] I. Food components (dyes)
[0139] Hard water (containing iron, etc.)
[0140] Soft drinks (tea, coffee, cocoa, cola, red wine, etc.)
[0141] II. Dyes produced by bacteria in the oral cavity
[0142] III. Tobacco
[0143] IV. Metallic vapor
[0144] V. Medications (disinfectants)
[0145] Intrinsic Coloration Factors
[0146] I. Pulp decay
[0147] II. Intrapulpal bleeding (injury, following extirpation of
pulp, arsenious acid)
[0148] III. Root canal filler components (amalgam, silver powder,
iodine, etc.)
[0149] IV. Tooth decay, rheumatic fever
[0150] V. Metabolic disorders, (congenital) ochronosis,
alcaptonuria, congenital erythropoietic porphyria, fetal
erythroblastosis, neonatal severe jaundice
[0151] VI. Medications (antibiotics, root canal treatment
drugs)
[0152] VII. Hard water (containing fluorine)
[0153] 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.
[0154] 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.
[0155] 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.
[0156] 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.
[0157] 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.
[0158] 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.
[0159] 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.sub.3,
KCl, K.sub.2HPO.sub.4.3H.sub.2O, MgCl.sub.2.6H.sub.2O, or
CaCl.sub.2 and Na.sub.2SO.sub.4, NaF, FeSO.sub.4, FeCl.sub.3, or
the like in water. It is preferable to adjust the pH to between 7
and 8 with HCl, (CH.sub.2OH).sub.3CNH.sub.2, or the like. Adjusting
the pH to 7.4 is particularly favorable.
[0160] The composition of the simulated body fluid used in the
present invention preferably comprises 120 to 1000 mM Na.sup.+, 1
to 200 mM K.sup.+, 0.5 to 100 mM Ca.sup.2+, 0.5 to 50 mM Mg.sup.2+,
80 to 2000 mM Cl.sup.-, 0.5 to 300 mM HCO.sub.3.sup.-, 1 to 200 mM
HPO.sub.4.sup.2-, 0.1 to 200 mM SO.sub.4.sup.2-, 0.5 mM F.sup.-,
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
(Ca.sub.9(PO.sub.4).sub.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.
[0161] The preferred temperature of the simulated body fluid is
from 30 to 100.degree. 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.degree. 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.
[0162] 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.
[0163] 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.
[0164] 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.
[0165] In one preferred embodiment of the calcium phosphate
pertaining to the present invention, this compound can be expressed
by the following general formula.
[0166] A.sub.x(BO.sub.y).sub.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.
[0167] 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.
[0168] 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 .mu.m. 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.sup.2/g. Below this, photoactivity
and adsorptivity will be poor.
[0169] 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.
[0170] 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 .mu.m and a specific surface area of at least 5
m.sup.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
[0171] FIG. 1 illustrates the cleansing system of the present
invention.
[0172] Key:
1 1 container component 2 irradiation component 3 lamp 4 lid
component 5 dental prosthetic 6 cleansing agent solution
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0173] The present invention will now be described in specific
terms through examples, but the present invention is in now way
limited by these examples.
EXAMPLES A
Example 1
[0174] 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.
[0175] 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.
Example 2
[0176] 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.
[0177] 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.
Example 3
[0178] 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.
[0179] 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.
Example 4
[0180] 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.degree. C. in a simulated
body fluid containing phosphoric acid ions and calcium ions. The
coverage was 1%.
[0181] 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.
Example 5
[0182] 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.
[0183] 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.
Comparative Example 1 (Cleaning with a Brush)
[0184] Tartar adhering to dentures was scrubbed with a denture
brush, but almost none could be removed, nor could the odor be
removed.
Comparative Example 2
[0185] A commercially available enzyme type of denture cleansing
agent was used according to the included instructions.
Specifically, 300 cc of 40.degree. 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.
Example 6
[0186] 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.
[0187] 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.
Example 7
[0188] 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.
[0189] 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.
Example 8
[0190] 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.
[0191] 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.
[0192] Reference Example (Manufacture of Photocatalyst Partially
Covered with a Compound Composed of at Least One
Ca.sub.9(PO.sub.4).sub.6 Unit)
[0193] 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.degree. C., and then dried at 100.degree. 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.sub.9(PO.sub.4).sub.6 unit.
Example 9
[0194] The TiO.sub.2 obtained in the Reference Example, which was
partially covered with a compound composed of at least one
Ca.sub.9(PO.sub.4).sub.6 unit, 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.
[0195] Staphylococcus aureus KPI S-96 and O-157 entero-hemorrhagic
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.degree. 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.degree. C., the product of which was
diluted with PBS to adjust the concentration to 1.2.times.105
CFU/mL O-157 and 1.2.times.10.sup.5 CFU/mL Staphylococcus aureus,
and then subjected to testing.
[0196] The test cloth was produced by cutting a JIS dye fastness
cotton test cloth into pieces measuring 5.times.5 cm, and
sterilizing these for 15 minutes in a 121.degree. C. autoclave.
[0197] 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.
[0198] No live bacteria of either O-157 or Staphylococcus aureus
could be recovered from the test cloth.
Examples B
Example
[0199] (1) Preparation of Cleansing Agent Solution
[0200] A cleansing agent solution was prepared from the following
components.
[0201] 0.05% titanium dioxide and apatite-covered titanium dioxide
(sol solution)
[0202] 1% phosphoric acid
[0203] 2% sodium pyrophosphate
[0204] water
[0205] (2) Apparatus
[0206] FIG. 1 shows the apparatus used in these examples.
[0207] 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.
[0208] (3) Cleansing Method
[0209] 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.
[0210] (4) Results
[0211] Table 1 shows the results. In Table 1, the units of "Energy
of 380 nm or lower" are mW/cm.sup.2. "Effect" indicates the extent
of the cleansing effect. "Temperature over 60.degree. C." indicates
the temperature range of the article being cleansed.
[0212] At an energy of 380 nm or lower (units: mW/cm.sup.2), there
was a cleansing effect at 10 mW/cm.sup.2 and above.
[0213] 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.degree. C. and a slight deformation in the resin was noted.
[0214] 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.sup.2, whereas a good effect was
not obtained when the energy of 380 nm or lower was less than 10
mW/cm.sup.2 or when the proportion of light with a wavelength of
430 to 800 nm was 80%.
2TABLE 1 Energy of Light 380 nm or Temperature Apparatus 1 source
lower Effect 430-800/200-800 nm over 60.degree. 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
[0215] (1) Measurement of Photoactivity
[0216] 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.
[0217] 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.times.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.sup.2 at 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.
[0218] The degree of photoactivity was defined as (L* value after
test)-(L* value before test)/(L* value before test).
[0219] (2) Preparation of Bleaching Agent
[0220] 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 calcium 1 to 4 are given as 1 to 4 in Table 3.
[0221] A simulated body fluid was prepared by using NaCl,
NaHCO.sub.3, KCl, K.sub.2HPO.sub.4.3H.sub.2O, MgCl.sub.2.6H.sub.2O,
CaCl.sub.2, and Na.sub.2SO.sub.4 or NaF, FeSO.sub.4, FeCl.sub.3, 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.
[0222] (3) Production of Tooth Bleaching System
[0223] 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.
[0224] (4) Bleaching of Discolored Teeth
[0225] Discolored teeth were bleached by the following procedure
using the above-mentioned bleaching agent.
[0226] 1) As pretreatment, detritus, tartar, tar, and so forth were
removed with an ultrasonic scaler.
[0227] 2) The surface of the teeth was cleaned with a rubber cup
and then dried, by a standard method.
[0228] 3) A simple moisture protection treatment was performed.
[0229] 4) The surface of the teeth was coated with each solution
and irradiated with visible light.
[0230] 5) With each iteration lasting 1 minute, the above-mentioned
coating with solution and optical irradiation were repeated 5
times, once every minute.
[0231] (5) Results
[0232] 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.
3TABLE 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
[0233]
4TABLE 3 Precipitates/ Na.sup.+ K.sup.+ Ca.sup.2+ Mg.sup.2+
Cl.sup.- HCO.sub.3.sup.- HPO.sub.4.sup.2- SO.sub.4.sup.2- F.sup.-
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
[0234] The degree of discoloration was classified as follows.
[0235] F1: Entire tooth crown was evenly colored pale yellow,
brown, or gray, with no stripes seen.
[0236] F2: Entire tooth crown was evenly colored more darkly than
F1, with no stripes seen.
[0237] F3: Dark gray or bluish gray stripes were included.
[0238] F4: Entire tooth crown was discolored in very dark purple or
grayish purple.
[0239] The effect was indicated as follows.
[0240] +++: Pronounced bleaching effect with improved whiteness
[0241] ++: Some bleaching effect noted, but coloration
(discoloration) remained.
Examples D
Examples 1 to 17
[0242] (1) Photoactivity
[0243] 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.
[0244] 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.times.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.sup.2 at 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.
[0245] The degree of photoactivity was defined as (L* value after
test)-(L* value before test)/(L* value before test).
[0246] (2) Photo-oxidation
[0247] 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.sub.2O/minute) was termed the oxygen absorption rate and used as
an index of photo-oxidation.
[0248] (3) Preparation of Compound of Phosphorus and Calcium
[0249] A simulated body fluid was prepared by using NaCl,
NaHCO.sub.3, KCl, K.sub.2HPO.sub.4.3H.sub.2O, MgCl.sub.2.6H.sub.2O,
CaCl.sub.2, and Na.sub.2SO.sub.4 or NaF, FeSO.sub.4, FeCl.sub.3, 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.
[0250] In Table 4, compositions 1 to 9 of the simulated body fluid
were as indicated by 1 to 9 in Table 5.
[0251] For comparison, commercially available hydroxyapatite made
by Wako was used. This apatite has relatively good crystallinity,
and its shape is spherical.
[0252] 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.
5TABLE 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
[0253]
6TABLE 5 Na.sup.+ K.sup.+ Ca.sup.2+ Mg.sup.2+ Cl.sup.-
HCO.sub.3.sup.- HPO.sub.4.sup.2- SO.sub.4.sup.2- F.sup.- 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
[0254] (4) Preparation of Paint
[0255] 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.
[0256] 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.
[0257] The following effects are realized with the present
invention.
[0258] (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.
[0259] (2) The final product can be in concentrated form.
[0260] (3) Better cleansing performance can be achieved through pH
control.
[0261] (4) The product readily dissolves before use, making it
easier to ship or carry around.
[0262] (5) The product is effective at deodorization.
[0263] (6) It is possible to provide a new type of sterilizing and
cleansing agent for cloths, fibers, and metal products.
[0264] (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.
[0265] (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.
[0266] (9) The cleansing effect of titanium dioxide and the like on
dental prosthetics can be enhanced by a simple process.
[0267] (10) A good cleansing effect can be obtained in a short
time.
[0268] (11) Stains on dental prosthetics can be completely cleansed
away without the use of any other cleansing means.
[0269] (12) A good cleansing effect can be obtained without
damaging dental prosthetics.
[0270] (13) It is possible to provide a novel bleaching agent for
discolored teeth.
[0271] (14) It is possible to bleach both medullated teeth and
nonmedullated teeth.
[0272] (15) Bacteria in the oral cavity can be effectively
eliminated.
[0273] (16) A bleaching effect can be obtained safely, with a
simple operation, and in a short time.
[0274] (17) The product has less of a psychological effect on the
patient.
[0275] (18) Color gradation can be controlled.
[0276] (19) It is possible to select the improvement in color
desired by the patient.
[0277] (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.
[0278] (21) The above-mentioned composition exhibits adequate
photoactivity for an environment cleaning material.
[0279] (22) The above-mentioned composition has good adsorptivity,
photoactivity, and biocompatibility.
[0280] (23) The above-mentioned composition has the action of
preventing bacteria and mold, odors, and stains, and of cleaning
the atmosphere or water.
[0281] (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.
[0282] (25) The above-mentioned composition can be used by coating
building materials (exterior or interior), vehicles (automobiles,
trains), and so forth.
* * * * *