JP5416510B2 - Tooth whitening or brightening screening method - Google Patents

Description

  The present invention relates to a whitening agent for whitening teeth and a screening method for tooth brighteners for improving tooth gloss.

  The cause of coloring of human teeth is mainly caused by adhesion of various colored substances to tartar, plaque, and the surface. Various physical or chemical methods have been reported as means for removing the cause of coloring of the tooth surface. As a physical method, in addition to removal by polishing, a method of removing a colored material using n-butyl ether or butyl butyrate (Patent Documents 1 and 2), or covering the teeth with a ceramic veneer or the like to adjust the color tone There is a way to improve. As chemical methods, a method for promoting remineralization with an oral composition containing hydroxyapatite (Patent Documents 3 and 4), a method for oxidative bleaching using a peroxide (Patent Document 5), a peroxide (Patent Document 6) using a tooth whitening composition containing a self-setting calcium phosphate compound and a fluorine compound, etc., and a method for promoting remineralization of enamel with a composition for oral cavity containing a liquefied calcium phosphate compound ( Patent Document 7) and the like are known. Moreover, the composition for oral cavity (patent document 8) which uses a polyvalent metal cation and polyphosphoric acid together and prevents tartar and dirt is known. However, the method of promoting tooth remineralization using calcium phosphate compounds such as hydroxyapatite mainly makes the teeth healthy by repairing the enamel surface with apatite. I can't say. Moreover, it cannot be said that there is a sufficient whitening effect even when polyphosphoric acid and a polyvalent metal cation are used in combination. And these conventional oral compositions and treatment methods do not impart gloss to the teeth themselves.

  In addition, the method using ceramic veneer or the like needs to delete the tooth quality, and the use of this method requires guidance and treatment by a dentist. The method of oxidative bleaching with peroxides requires the use of a high concentration of peroxide that enables oxidative bleaching of the teeth. The gloss is reduced. In addition, even under the guidance of specialists, peroxides may cause damage to the teeth and gums and hypersensitivity.

JP-A-1-203316 JP-A-1-104004 JP-A-1-305020 JP-A-9-202718 JP 2005-526853 A JP-A-11-116421 JP-A-8-319224 JP-A-52-108029

As described above, although searching for a component that makes teeth white and improves the gloss of the teeth is eagerly desired, the searching means is not known at all.
Accordingly, a first object of the present invention is to provide a whitening agent capable of giving an excellent whitening effect to teeth and imparting gloss, and a method for screening for a brightening agent.
Conventionally, for example, Patent Document 5 is applied to a subject (human tooth), and the L whitening effect is confirmed by measuring the L value. In Patent Document 6, it is applied to a human extracted tooth. The whitening effect has been confirmed visually, but when applied to human teeth, the number is limited, and it is necessary to evaluate not only the appearance whiteness but also the damage to the teeth and the effect of improving the gloss. is there. Therefore, the second object of the present invention is to provide a whitening agent capable of giving an excellent whitening effect to teeth and imparting gloss, and a method for efficiently screening without using human teeth.

The enamel of a tooth is made up of a collection of columnar bodies made of hydroxyapatite polycrystals called enamel trabeculae. In general, in the youth, a space (gap), that is, a trabecular space exists between the enamel trabeculae and the enamel trabeculae, and is filled with water, saliva components, and the like. In such a tooth, the incident light to the enamel is scattered due to a large difference in refractive index between the enamel trabeculae and the space between the trabeculae, and the teeth appear white.
However, if the substance dissolved in saliva continues to accumulate in the trabecular space of the tooth enamel surface, for example due to aging, the trabecular space is filled, and as a result, the refractive index of the enamel trabecular space is smaller than that of the trabecular space. Since the difference becomes smaller, the enamel becomes more transparent and the incident light tends to reach yellow or brown dentin located deep in the enamel, and the teeth appear yellow.
Therefore, the present inventors have formed enamel by selectively removing from the trabecular space a material (hereinafter referred to as “trabecular space material”) present in the trabecular space of the tooth enamel surface layer. By re-forming the trabecular gap while suppressing damage to the enamel trabecula itself, and increasing the reflected light from the inside of the enamel by light scattering by the space of the trabecular gap, natural white teeth can be obtained Thought.
Further, the present inventors have found that the interstitial material is mainly composed of low crystalline, low crystalline hydroxyapatite unlike the highly crystalline hydroxyapatite forming the enamel trabeculae. I found. Furthermore, the fine solid product on the tooth surface is a deposit of nano-level solid products having a thickness of 200 nm or less, preferably 100 nm or less. These nano-level solid products also have a low crystalline hydroxy content. It has been found that deposits of components such as calcium and phosphorus mainly composed of apatite are deposited. Furthermore, high crystalline hydroxyapatite forming enamel trabeculae and low crystalline hydroxyapatite forming trabecular interstitial materials are distinguished by the half width of (300) plane by powder X-ray diffraction method. I also found what I can do.
The present inventors pay attention to the difference in crystallinity of this hydroxyapatite, and the components whose solubility in low crystalline hydroxyapatite is higher than the solubility in high crystalline hydroxyapatite, that is, the trabecular space substance and the tooth surface. A whitening agent that re-forms the trabecular space while suppressing damage to the trabecular space of the enamel by selecting components that can selectively dissolve and remove the small solid product, and fine solids on the tooth surface It has been found that brighteners that selectively remove the product can be screened.

  That is, the present invention relates to a low crystalline hydroxyapatite having a half-value width of 0.45 ° or more of the (300) plane of the hydroxyapatite crystal in the powder X-ray diffraction method using (A) CuKα ray as the test component. Solubility, (B) the half-value width of the (300) plane of hydroxyapatite crystals in a powder X-ray diffraction method using CuKα rays is 0.45 ° or less, and the half-value of the low crystalline hydroxyapatite The solubility in highly crystalline hydroxyapatite is 0.1 ° or more smaller than the width, and (A) the solubility in low crystalline hydroxyapatite is (B) 1.6 times the solubility in highly crystalline hydroxyapatite The present invention provides a screening method for a tooth whitening agent or a tooth brightening agent, in which an ingredient is selected. Hereinafter, the (300) plane of the hydroxyapatite crystal in the powder X-ray diffraction method using CuKα rays is referred to as the (300) plane by X-ray diffraction.

ADVANTAGE OF THE INVENTION According to this invention, the component which can provide the whitening effect and the glossiness which were excellent in the tooth | gear, suppressing the damage to a trabecular space can be screened.
In order to confirm the components that can selectively remove the trabecular space material and nano-level solid products on the tooth surface, obtain untreated human extracted teeth with trabecular space material buried in the trabecular space, It is thought that screening can be performed by applying the test component and observing the space between the trabecula and the tooth surface with a scanning electron microscope or the like. However, an observation process with an electron microscope or the like is required, and the untreated human is removed. There is also a limit to the number of teeth you can get. On the other hand, according to the present invention, if two types of hydroxyapatite having different crystallinity are prepared, a tooth whitening agent and a brightener can be screened easily and in large quantities.

The SEM photograph of Taihei Chemical HAP-100 (a) and Taihei Chemical HAP-200 (b) is shown.

  Two types of hydroxyapatite having different crystallinity used in the screening method of the present invention are (A) low crystalline hydroxyapatite having a half-value width of (300) plane of 0.45 ° or more by X-ray diffraction, and (B ) A highly crystalline hydroxyapatite having a half width of (300) plane of 0.45 ° or less by X-ray diffraction and (A) 0.1 ° or more smaller than the half width of low crystalline hydroxyapatite. .

The half width is the width of the diffraction intensity curve at ½ intensity of the peak intensity of the X-ray diffraction intensity curve, and is known as a measure of crystal regularity, ie crystallinity, measured in X-ray diffraction. Yes. That is, it is determined that the crystallinity is low when the half width is large, and the crystallinity is high when the half width is small.
Moreover, the X-ray diffraction in this invention is measured on condition of the following.
The apparatus uses RINT-2500 manufactured by Rigaku Corporation and performs X-ray diffraction measurement under the following measurement conditions.
Measurement conditions are CuKα (λ = 1.541Å) as an X-ray source, voltage: 40 kV, current: 120 mA, scan speed 10 ° / min, sampling width 0.01 °, divergence slit 1 °, divergence longitudinal slit. Measurement is performed with 10 mm and a light receiving slit of 0.3 mm.
An X-ray diffraction profile of 2θ-intensity is drawn, and peak separation fitting is performed in the range of 2θ = 20 ° to 45 ° using analysis software Jade 5.0 installed in the apparatus, and the (002) plane of the hydroxyapatite hexagonal system ( The diffraction peaks of the (102) plane, (210) plane, (211) plane, (112) plane, (300) plane, (202) plane, etc. are obtained. Of these, the half width of the diffraction peak on the (300) plane is used as an index.

  The (A) low crystalline hydroxyapatite used in the present invention has a (300) plane half width of 0.45 ° or more, more preferably 0.46 ° or more, as determined by X-ray diffraction. The upper limit of the half width is preferably 0.9 °. As a commercially available product, for example, HAP-100 manufactured by Ohira Chemical Co., Ltd. may be mentioned.

The (A) low-crystalline hydroxyapatite used in the present invention can be synthesized from, for example, (a) calcium glycerophosphate, (b) dipotassium hydrogen phosphate, and (c) a fluoride ion feed compound. (C) As a fluoride ion supply compound, sodium fluoride, potassium fluoride, ammonium fluoride, etc. are mentioned, and sodium fluoride is preferable. Specifically, it can be synthesized by mixing a calcium glycerophosphate solution with a mixed solution of dipotassium hydrogen phosphate and sodium fluoride. If a plate is placed in this calcium glycerophosphate-containing mixed solution, a film-like (A) low crystalline hydroxyapatite can be obtained. It is preferable to form a film by placing a white acrylic plate in a calcium glycerophosphate-containing mixed solution assuming the actual tooth surface.
In addition, (A) low crystalline hydroxyapatite can also be obtained as a powder form, and the said powder form thing can also be used.
(A) As for the liquid mixture which synthesize | combines low crystalline hydroxyapatite, what contains 0.005-0.5M of (a) calcium glycerophosphate is preferable, and what contains 0.01-0.2M is further preferable. (B) Dipotassium hydrogen phosphate preferably contains 0.005 to 0.5M, more preferably 0.01 to 0.2M. (C) The fluorine ion supply compound preferably contains 0.001 to 0.2M, more preferably 0.002 to 0.1M. The molar ratio [(a or b): c] of component (a) or component (b) to component (c) is preferably 1: 1 to 10: 1, and more preferably 2: 1 to 6: 1.

  The (B) highly crystalline hydroxyapatite used in the present invention has a half-value width of (300) plane of 0.45 ° or less by X-ray diffraction, and is 0.1 ° less than (A) the low crystalline hydroxyapatite. Although it is small above, the thing smaller than 0.15 degree is more preferable. The half width of the (300) plane by X-ray diffraction is preferably 0.4 ° or less, more preferably 0.35 ° or less, and particularly preferably 0.3 ° or less. Further, the lower limit of the half width is preferably 0.10 °. The half-value width in the (300) plane of the human tooth enamel is between 0.184 and 0.284 °, although it varies depending on age, tooth damage and the like. Moreover, as a commercial item, Ohira-made HAP-200 is mentioned, for example, It is thought that it is a hydroxyapatite near a human tooth.

The (B) highly crystalline hydroxyapatite used in the present invention can be synthesized from, for example, (d) calcium chloride or calcium lactate, (b) dipotassium hydrogen phosphate and (c) a fluoride ion supplying compound. Specifically, it can be synthesized by mixing a solution of calcium chloride with a mixed solution of dipotassium hydrogen phosphate and sodium fluoride. If a plate is placed in this calcium chloride-containing mixed solution, a film-like (B) highly crystalline hydroxyapatite can be obtained. Assuming the actual tooth surface, it is preferable to form a film by placing a white acrylic plate in a mixed solution containing calcium chloride.
In addition, (B) highly crystalline hydroxyapatite can also be obtained as a powder form, and the said powder form thing can also be used.
(B) The liquid mixture for synthesizing highly crystalline hydroxyapatite is preferably (d) containing 0.005-0.5M calcium chloride or calcium lactate, and more preferably containing 0.01-0.2M. . (B) Dipotassium hydrogen phosphate preferably contains 0.005 to 0.5M, more preferably 0.01 to 0.2M. (C) The fluorine ion supply compound preferably contains 0.001 to 0.2M, more preferably 0.002 to 0.1M. The molar ratio [(d or b): c] of component (d) or component (b) to component (c) is preferably 1: 1 to 10: 1, and more preferably 2: 1 to 6: 1.

  Fig. 1 (a) shows a photograph of HAP-100 (example of low crystalline hydroxyapatite) manufactured by Ohira Chemical Co., Ltd. by SEM (electron microscope: Hitachi S-4800), and Fig. 1 (b) shows a product manufactured by Ohira Chemical Co., Ltd. The photograph by SEM of HAP-200 (example of highly crystalline hydroxyapatite) is shown. The SEM photograph shows the difference in crystallinity.

  The screening method of the present invention measures the solubility of a test component in (A) low crystalline hydroxyapatite and (B) the solubility in high crystalline hydroxyapatite, and the solubility ratio (A / B ) Is 1.6 times or more, preferably 2 times or more, more preferably 2.5 times or more. Here, the solubility measuring means is not particularly limited, but the residual amount after dissolution of (A) low crystalline hydroxyapatite and (B) high crystalline hydroxyapatite may be measured, or from the hydroxyapatite Any of the measurement of calcium ion elution amount may be used.

  The solubility of hydroxyapatite can be determined by measuring the residual amount of hydroxyapatite after dissolution. For example, it is applied by bringing a hydroxyapatite film into contact with a test component-containing liquid for a certain period. The contact method is carried out by immersing the hydroxyapatite film in the test component-containing liquid or applying a porous member impregnated with the test component-containing liquid to the hydroxyapatite film. The contact time is, for example, preferably 5 seconds to 3 minutes, more preferably 10 seconds to 1 minute. And after contact or immersion, it rinses with ion-exchange water for 1 to 3 seconds and dries. By measuring the surface reflectance before contact with the test component and after contact and drying, and measuring the amount of film before and after dissolution of the film, solubility can be evaluated and screened. Screening based on the solubility of these films is based on the removal rate (solubility) of the film, and (A) the removal rate of the low crystalline hydroxyapatite film and (B) the removal rate of the highly crystalline hydroxyapatite film. The ratio (A / B) is 1.6 times or more, preferably 2 times or more, more preferably 2.5 times or more, and particularly preferably 3 times or more. For example, when the hydroxyapatite film is immersed in a test component-containing solution for 10 seconds, the removal rate of the (B) highly crystalline hydroxyapatite film is less than 50%, preferably 25% or less, more preferably 20% or less. Certain components can be screened. Further, the hydroxyapatite film was immersed in the test component-containing solution for 10 seconds. (A) The removal rate of the low crystalline hydroxyapatite film was 55% or more, preferably 80% or more, more preferably 90% or more. Certain components can be screened. The screened ingredients whiten the teeth to recreate the trabecular space while reducing damage to the tooth enamel trabecular space and the tooth enamel surface, and the fine solid products on the tooth surface. Since it is selectively removed, the effect of improving gloss is recognized.

  When measuring the calcium elution amount from hydroxyapatite, the calcium elution amount from hydroxyapatite is measured after applying hydroxyapatite for a certain period of time in the test component-containing solution. In the selection of the tooth whitening agent and tooth brightener of the present invention, the ratio (A / B) of calcium elution amount of the test component (B) high crystalline hydroxyapatite and (A) low crystalline hydroxyapatite is 1 The component is selected 6 times or more, preferably 2 times or more, more preferably 2.5 times or more.

  For example, when (B) HAP-200 manufactured by Taihei Chemical Co., Ltd. is used as the high crystalline hydroxyapatite, and (A) HAP-100 manufactured by Taihei Chemical Co., Ltd. is used as the low crystalline hydroxyapatite, Screening can be performed by immersing the HAP-200 and HAP-100 powders for 1 minute to 1 hour, more preferably 10 minutes to 40 minutes, and measuring the amount of calcium dissolved in each powder. The calcium dissolution amount is expressed in mg / kg as the dissolution amount with respect to 1 kg of the test ingredient-containing solution. In the case of screening based on the dissolution amount of HAP-200 and HAP-100 powders, HAP-200 powder 50 g each was applied to 1 g HAP-200 powder and 1 g HAP-100 powder for 30 minutes. The calcium elution amount from 200 is 250 mg / kg or less, preferably 100 mg / kg or less, more preferably 80 mg / kg or less, and the calcium elution amount from HAP-100 is 100 mg / kg or more, preferably 150 mg. / Kg or more components can be screened. The screened ingredients whiten the teeth to recreate the trabecular gap and remove minute solid products on the tooth surface while reducing damage to the tooth enamel trabecular space and tooth enamel surface. And the effect of improving gloss is recognized.

"Preparation of low crystalline hydroxyapatite film and high crystalline hydroxyapatite film"
(1) Low crystalline hydroxyapatite film (GPCa film): A white acrylic plate is put in a 200 mL beaker, and 30 mL of 0.1 M dipotassium hydrogen phosphate solution and 10 mL of 0.05 M sodium fluoride solution are put therein. After stirring and mixing, 50 mL of 0.05 M calcium glycerophosphate solution was stirred and mixed, and then stirred and mixed for 1 hour. It was confirmed that the formed film of the calcium glycerophosphate-containing mixed solution had a half width of 0.64 to 0.82 ° on the (300) plane by X-ray diffraction.
(2) Highly crystalline hydroxyapatite film (CaCl ₂ film): A white acrylic plate is placed in a 200 mL beaker, and 30 mL of 0.05 M dipotassium hydrogen phosphate solution and 10 mL of 0.05 M sodium fluoride solution are added thereto. After stirring and mixing, 50 mL of 0.05M calcium chloride solution was stirred and mixed, and then stirred and mixed for 1 hour. It was confirmed that the formed film of calcium chloride-containing mixed solution had a half-value width of 0.346 ° on the (300) plane by X-ray diffraction.

“Measurement of solubility of low crystalline hydroxyapatite and high crystalline hydroxyapatite membranes”
(1) Treatment: A white acrylic plate with a low crystalline or highly crystalline hydroxyapatite film is immersed for 10 seconds in a test solution containing 1% by mass of the test target component and pH adjusted with NaOH. Rinse with ion exchange water for 1-2 seconds and dry.
(2) Evaluation of film solubility by measuring relative reflectivity: The relative reflectivity shown in (3) below is measured after the preparation of hydroxyapatite film and after the treatment, and the decrease in relative reflectivity after film preparation ( 100-relative reflectivity after film preparation) and relative reflectivity after treatment were calculated to calculate the film removal rate and to express the solubility of the film.
Film removal rate (%) = (Relative reflectance after treatment−Relative reflectance after film production) / (100−Relative reflectance after film production) × 100
(3) Relative reflectance measurement method: A method of measuring the surface reflected light intensity from image analysis using polarized light was used. As a device for taking images for evaluation, the camera is a digital single-lens reflex camera Nikon D70, the lens is an Ai AF micro Nikkor 105mm F2.8D, and the flash emission is a wireless remote speedlight SB-R200 (all manufactured by Nikon). The installed one was used. Photographing was carried out by placing a plastic polarizing plate (manufactured by Edmond) in front of the light emitting part of the speedlight and the lens so that the transmission axes intersected 30 degrees. For the captured image, the average brightness of the highlight portion was determined by using Adobe Photoshop CS3 (manufactured by Adobe System). The luminance from the white acrylic plate was also obtained, and the relative reflectance was obtained with the image luminance of the white acrylic plate as 100.

"Measurement of calcium solubility in low crystalline hydroxyapatite powder and high crystalline hydroxyapatite powder"
HAP-100 and HAP-200 made by Taihei Chemical Sangyo Co., Ltd. were used as powders of low crystalline hydroxyapatite and high crystalline hydroxyapatite.
The half width at the (300) plane by X-ray diffraction of this HAP-100 is between 0.460 and 0.467 °, and the half width at the (300) plane by X-ray diffraction of HAP-200 is 0.00. It was between 182 and 0.197 °. By measuring the calcium dissolution amount described below, the dissolution amount in a solution containing the test component to be screened was determined using these two types of hydroxyapatite. Screening was performed by comparing values of calcium dissolution of each hydroxyapatite powder.
1 g of each hydroxyapatite powder is precisely weighed, immersed in 50 mL of a test solution containing 1% by mass of each test target test component, stirred for 30 minutes, and the suspension is filtered through a membrane filter having a pore diameter of 0.45 μmφ. The Ca ions eluted in the filtrate were quantified with ICP-AES (apparatus: ICP emission spectrometer, Horiba, Ltd., JY238ULTRACE), the amount of Ca ions in the test solution was expressed in mg / kg, and the test component calcium The amount dissolved was used.

"Evaluation of color difference and gloss"
Table 1 shows a 1% by weight aqueous solution of each test component (component to be screened) as a test solution. When human teeth are immersed for 48 hours, changes in b ^* values before and after immersion Δb ^* and gloss are evaluated. Hydroxyapatite film Evaluation results of calcium dissolution amount by hydroxyapatite powder are shown. The pH was adjusted with a NaOH solution.
The human tooth used for the test is a sample in which the other part is covered with wax while leaving the enamel surface to be evaluated for Δb ^* and gloss.
Change before and after dipping in the b ^* value at the time of the human teeth were immersed at room temperature for 48 hours [Delta] b ^* in each test solution, and measuring the b ^* value after immersion with before immersion, (after immersion b ^* - before immersion b ^* )
This b ^* value is an L ^* a ^* b ^* color system obtained by using Adobe Photoshop (manufactured by Adobe Systems) for an image photographed using a digital camera D1x (manufactured by Nikon) and a white flash light source (manufactured by Konica Minolta). Represented and sought. The closer the value of b ^* is to 0, the less yellowish the whiteness increases, and the larger -Δb ^* (Δb ^* absolute value) means the whiteness increases.
The gloss of the teeth is evaluated by an image taken using a digital camera D1x (Nikon) and a white flash light source (Konica Minolta). (Magnification 10 times) was observed with the naked eye and evaluated according to the following criteria.
-: No change 5: Glossiness appeared on the entire surface 4: Glossiness was observed except for a part 3: Glossiness was partially exhibited 2: Concavities and convexities were partially formed 1: Concavities and convexities were formed on the entire surface

As shown in Table 1, in the human tooth test, the absolute value of Δb ^* was 1.5 or less, and Test Example 1 in which no change in gloss was observed is the Ca elution amount of HAP-100 and HAP-200. The film removal rates of the GPa film and the CaCl ₂ film were all low, and the Ca elution ratio (HAP-100 / HAP-200) and the film removal ratio (GPa film / CaCl ₂ film) were also less than 1.6. Further, in the test examples 2, 7, and 8 in which the absolute value of Δb ^* was 1.5 to less than 3 and no change in gloss was observed in the human tooth test, the Ca elution amount and the film removal rate were low, and the Ca elution amount The ratio (HAP-100 / HAP-200) and membrane removal ratio (GPa film / CaCl ₂ film) were less than 1.6. Furthermore, although the absolute value of Δb ^* was 3 or more in the test of human teeth, Test Examples 9 and 11 in which irregularities were formed on the surface of the tooth were the amount of Ca elution of HAP-100 of low crystalline apatite and the GPa film. The removal rate of HAP-200, a highly crystalline apatite, and the removal rate of CaCl ₂ film are as high as this, and both the Ca elution amount ratio and the membrane removal ratio are less than 1.6. there were.
In contrast, in Test Examples 3 to 5, 10, 12, and 13 in which high results of 1.6 or more in Ca elution amount and membrane removal ratio were obtained, the absolute value of Δb ^* was 3 in the human tooth test. The gloss was also obtained.

From Table 1, according to the method of the present invention, (A) the amount of Ca elution and membrane removal for low crystalline hydroxyapatite is 1.6 or more with respect to the amount of Ca elution and membrane removal for (B) high crystalline hydroxyapatite. By selecting Test Examples 3-5, 10, 12, and 13 with high results, even when applied to human teeth, gloss is imparted without damaging the teeth, and the color difference of the teeth A brightener exhibiting a whitening effect with an absolute value of (Δb ^* ) of 3 or more can be selected.

Claims (8)

Powder X-rays synthesized from a mixed solution of (A) (a) calcium glycerophosphate, (b) dipotassium hydrogen phosphate and (c) a fluorine ion supply compound as test components. (B) (d) calcium chloride or calcium lactate , (B) solubility in low crystalline hydroxyapatite having a half-value width of the (300) plane of 0.46 ° to 0.9 ° in the diffraction method , b) synthesized from a mixed solution of dipotassium hydrogen phosphate and (c) fluorine ion supply compound, and the half-value width of the (300) plane of the hydroxyapatite crystal in the powder X-ray diffraction method using CuKα rays is in 0.4 ° below 0.10 ° or more, and for that low-crystalline 0.15 ° or more than the half width of the hydroxyapatite small highly crystalline hydroxyapatite A method for screening a tooth brightener, comprising measuring a desolubility and selecting (A) a component whose solubility in low crystalline hydroxyapatite is (B) 1.6 times or more of the solubility in high crystalline hydroxyapatite . The solubility of the test component in low crystalline hydroxyapatite having a half-value width of 0.64 to 0.82 ° of the (300) plane of the hydroxyapatite crystal in the powder X-ray diffraction method using (A) CuKα ray (B) The solubility in high crystalline hydroxyapatite having a half-value width of (300) plane of the hydroxyapatite crystal of 0.35 ° or less in the powder X-ray diffraction method using CuKα ray is measured. (A) A method for screening a tooth brightener, wherein a component having a solubility in low crystalline hydroxyapatite (B) that is 1.6 times or more of the solubility in high crystalline hydroxyapatite is selected. The solubility of the test component in (A) the low crystalline hydroxyapatite and the solubility of the test component in (B) the high crystalline hydroxyapatite are the (A) low crystalline hydroxyapatite and (B) high in the test component. The screening method according to claim 1 or 2, wherein the measurement is conducted by contacting crystalline hydroxyapatite for 5 seconds to 1 minute. (A) Low crystalline hydroxyapatite and (B) high crystalline hydroxyapatite are in the form of a film, and the solubility of the test component in (A) low crystalline hydroxyapatite and the test component (B) high crystalline hydroxy The screening method of any one of Claims 1-3 which evaluates the solubility with respect to apatite by the removal rate of a film | membrane . The screening method according to any one of claims 1 to 4 , wherein the solubility measurement means is measurement of calcium ion elution amount from (A) low crystalline hydroxyapatite and (B) high crystalline hydroxyapatite. (A) The content of the component (a) in the mixed solution of (a) calcium glycerophosphate, (b) dipotassium hydrogen phosphate and (c) fluorine ion supply compound for synthesizing the low crystalline hydroxyapatite is 0 0.005 to 0.5M, the content of component (b) is 0.005 to 0.5M, and the content of component (c) is 0.001 to 0.2M, and
(B) Inclusion of component (d) in a mixture of (d) calcium chloride or calcium lactate, (b) dipotassium hydrogen phosphate and (c) fluorine ion supplying compound for synthesizing highly crystalline hydroxyapatite The amount is 0.005 to 0.5M, the content of component (b) is 0.005 to 0.5M, and the content of component (c) is 0.001 to 0.2M. The screening method according to any one of 1 to 5. Further, (A) from the powdery low crystalline hydroxyapatite in which the half-value width of the (300) plane of the hydroxyapatite crystal in the powder X-ray diffraction method using 'CuKα ray is 0.45 ° or more as a test component. And (B) the half width of the (300) plane of hydroxyapatite crystals in a powder X-ray diffraction method using 'CuKα rays is 0.45 ° or less, and the low crystalline hydroxyapatite Calcium ion elution amount from powdery high crystalline hydroxyapatite smaller than half width by 0.1 ° or more is measured. (A) 'Calcium ion elution amount from powdery low crystalline hydroxyapatite is (B The component according to any one of claims 1 to 6, wherein a component that is 1.6 times or more the calcium ion elution amount from the powdery highly crystalline hydroxyapatite is selected. Ningu way. (A) Low crystalline calcium ion elution amount from the hydroxyapatite (B) according to any one of claims 1-7 for selecting a highly crystalline at least twice a component of calcium ion elution amount from the hydroxyapatite Screening method.