JP5618133B2 - Glass polyalkenoate cement for sealing dental pits and fissures - Google Patents

Description

  The present invention relates to a foveal fissure plugging material, which is a preventive dental material used for preventing dental caries and suppressing the progress of carious teeth by plugging the small fossa fissure which is a narrow gap in which caries are likely to occur in preventive dentistry ( The present invention relates to a glass polyalkenoate cement for sealing dental pits and fissures used as a sealant material.

  Cavity fissure filling method (sealant) that seals the fossils that are pits and fissures with a sealant material is used for deciduous fossa crevices, bony fissures, buccal lateral grooves and maxillary anterior teeth of young permanent teeth. It is appropriate to treat the side of the palate immediately after tooth eruption.

  The most common disease in children is caries. One reason for this is that new teeth are not hard enough, and it takes two to four years to grow before calcification progresses completely. Another factor is the preference for beverages and sweets that contain sugar. It has been reported that more than 80% of pediatric caries originate from narrow grooves (pits and fissures) in the molars that cannot be reached by the toothbrush. In addition, it has been found that the caries generated mainly from the pits and fissures are generated regardless of sugar intake and frequency. For this reason, the use of fluoride in the dental clinic and the use of fluoride are particularly important for the prevention of caries in children today.

  The sealant that fills the sealer with a sealant is a method for preventing caries that physically seals the grooves of the back teeth and promotes the remineralization action by the fluoride contained in the filler. Sealant was first reported in 1967 by Cueto and Buonocore for clinical success. About 4% of caries preventive effect is recognized in 4 years or more, and the caries preventive effect is further increased by the combined use with fluoride application. Sealants are particularly effective when applied to teeth that have a high risk of caries development.

  The improvement of sealant material has greatly contributed to the background of the prevention of caries by sealant as it is today. In addition to physically sealing the back tooth groove with glass ionomer cement (GIC), the back tooth groove is physically sealed with a resin. There are methods in which a chemical promotes remineralization.

Resin-based sealant materials for use in sealants have been developed. However, the resin-based sealant material has various drawbacks compared to the GIC-based sealant material.
The adhesive resin sealant material developed by Buonocore (see Non-Patent Document 1) in 1955 has been improved since then, and the photopolymerization type is widely used today. However, resin-based sealant materials are indispensable for (1) tooth decalcification treatment with an acid in order to adhere to the tooth. Most teeth that require sealant are immature young teeth that are poorly calcified, but resin sealants that block the tooth structure from the oral environment (2) inhibit postmature maturation of young permanent teeth. There is a drawback. In recent years, therefore, resin-based sealant materials that release fluorine gradually have been made as countermeasures against tooth damage caused by tooth demineralization and inhibition of maturation after eruption. However, a certain effect has not been recognized. further,
(3) A rubber dam must be installed to prevent saliva contamination and moisture. Moreover,
(4) If the resin sealant material is partly detached, the possibility of secondary caries is higher than that of teeth that do nothing, so regular management in the dental clinic is required.
(5) The resin-based sealant material has been confirmed to be cytotoxic in in vitro studies, and concerns regarding the safety of bisphenol A contained in the resin have not been dispelled.

  In order to compensate for the drawbacks of this resin-based sealant material, glass ionomer cement (also referred to as glass polyalkenoate-based cement) -based sealant material (hereinafter referred to as GIC-based sealant material) is on the market. The advantages of GIC-based sealant materials are that no acid treatment is required, rubber dams are not required, fluorine is sustainedly released for a long time, and even if it is desorbed, the tooth structure is strengthened by fluorine, and the possibility of caries generation Since it is extremely small, it can be applied to cases where regular management is impossible. Furthermore, biocompatibility is superior to resin-based sealants.

  The GIC sealant material has characteristics superior to those of the resin sealant material, but further excellent fluorine sustained release ability is required. However, the conventional GIC sealant material has a drawback that the sustained release ability of fluorine is not sufficient.

  By the way, as a sealant material, the influence on the generation of a total of six materials including four resin-based materials and two glass ionomer-based materials has been investigated from the beating rate of cardiomyocytes differentiated from mouse-derived ES-D3 cells. In the experiment, three parameters including 50% cell differentiation rate (ID50) and 50% cell viability (IC50) of the same cell and other differentiated cells of the same type (Balb / c 3T3cell) were used. It has been studied by the Embryonic Stem Cell Test method for predicting developmental toxicity. As a result, an average of 6.4 to 9.2 g / ml for the resin 50 was obtained for ID50. In the liquid of GIC system 2 material, the average is 157.3 g / ml in Fuji III, and 54.1 g / ml in Fuji III LC. The IC50 of both cells shows similar results to ID50. On the other hand, ID50 and IC50 cannot be obtained with the powder of GIC system 2 material. In addition, regarding the cytotoxicity of the cured material examined at the same time, the resin-based 4 materials show stronger cytotoxicity than the GIC system.

  As described above, the resin-based material as the sealant material was weak, but the result was a suspicion of the developmental toxicity, whereas the liquid of the GIC-based two material has no suspicion of the developmental toxicity.

  By the way, the use of sealants is promoted in the 2004 statement of the Center for Prevention and Prevention of the United States. In this statement, the sealant that fills the occlusal surface of the molar part with Plastec is a safe and effective method for preventing caries for children. There have already been cases where the initial cavity is stopped. Sealants significantly reduce the risk of children with untreated cavity.

  For this reason, “Healthy People 2010” in the United States has set a target so that 50% of children will have a sealant by 2010. CDC researchers have evaluated a number of strategies and acknowledged that sealant treatment for economically underprivileged schoolchildren is the most cost-effective way to correct gaps in sealant use. In addition, the Special Headquarters for Community Prevention Services recommends school-based sealant programs or school-related sealant programs as an effective method for preventing and controlling caries.

  Furthermore, in the International Dental Federation (FDI) statement (2001), extensive research worldwide over 50 years has consistently shown the safety and effectiveness of fluoride for caries prevention. The scientific basis for fluoride use and safety is recognized by countless scientists, expert groups, and government agencies. The use of fluoride has reduced the incidence and prevalence of caries, leading to improvements in the quality of life for many people. It has now been found that the most important factor is the constant supply of the appropriate concentration of fluoride in the oral cavity. The presence of low-concentration fluoride suppresses enamel demineralization and promotes remineralization. These findings are very important when considering the use of fluoride as a preventive and therapeutic measure. It has been confirmed that the topical application of fluoride, or any means of maintaining the proper concentration of fluoride in the oral cavity, is extremely important for caries prevention.

The inventor of the present invention pays attention to the fact that GIC reacts quickly at the boundary with the tooth which is hydroxyapatite (HAp) to generate a new product, which is chemically bonded to the tooth surface without any treatment. By realizing this state in the entire GIC, the mechanical strength of the GIC in the cured state was improved, and this was successfully used for dental filling glass polyalkenoate cement. The GIC used in this glass polyalkenoate cement for dental filling is added and mixed with a specific HAp to form a new compound at the boundary between the GIC and the glass powder and harden the whole to increase the mechanical strength. Improve. (See Patent Document 2)
The GIC used for this glass polyalkenoate cement for filling can increase the mechanical strength from the early stage of curing of GIC by reacting hydroxyapatite and glass powder quickly at the boundary.

  The GIC of Patent Document 2 is conceived from the fact that it is chemically reacted with a tooth that is about 95% HAp and bonded, and the GIC of the bonded portion is stronger than most of the other. This dental filling glass polyalkenoate cement is made by adding a specific HAp and mixing it to cause a reaction that occurs at the boundary between the tooth and the GIC to occur at the boundary between the GIC glass powder and the hydroxyapatite. By curing the whole, the mechanical strength was successfully increased from the initial stage of curing.

  By the way, in recent years, the concept of Minimal Intervention (MI) has been spreading worldwide in dentistry, and the frequency of use of GIC, which is a dentine adhesive material and has high tissue affinity, has been increasing. In particular, the chemically hardened GIC is used as a restoration material for Atraumatic Restrative Treatment (ART) in developing countries by WHO, and it is a glass polyalkenoate system for dental filling that fills the cavity of the cavity without shaving the teeth. By using it as a cement, it prevents the progress of cavity and prevents the generation of new cavity, and is highly evaluated and effective for its treatment. Therefore, the provision of a high-quality and safe chemical-hardening type GIC that adheres to teeth without treatment as shown in Patent Document 2 is an urgent issue in the world, preventing caries from all human beings, It provides a very good gospel that can be treated in an ideal condition without pain. The GIC filled in the cavity of the cavity without scraping the teeth can prevent the progress of the cavity and prevent the generation of a new cavity because of the secondary caries suppression effect by the release (release) and uptake (recharge) of fluoride ions and It is because it produces an antibacterial action.

Special table 2007-524635 Japanese Patent Application No. 2008-513227 Buonocore, M. G .: Caries prevention in pits and fissures sealed with adhesive resin polymerized by ultraviolet light: A two year study of a single adhesive application.J.A.D.A. 82: 1090-1093, 1971. Wada, Toshiri: Basic research on various pit and fissure sealing materials. Fukuoka Dental University Journal, 22 (2): 229-246, 1995.

  As described above, the GIC described in Patent Document 2 was developed as a GIC that can treat dental caries and the like without shaving teeth, but by increasing the amount of liquid and reducing the powder-liquid ratio, the dental pits It has the potential to be used for fissure sealing. If this can be achieved, it will be an ideal treatment method, especially in developing countries, and it will prevent dental caries in an ideal state in those countries where dental treatment is not sufficient.

  However, it is difficult for the glass polyalkenoate-based cement described in Patent Document 2 to smoothly enter into the pits and fissures, which are narrow gaps, and it is necessary to use a specific hydroxyapatite. In addition, there is a drawback that the price is extremely high, and that the mechanical strength is remarkably lowered by increasing the amount of liquid, and the amount of fluorine ions released is not sufficient.

The GIC sealant material used for this purpose is required to have the following characteristics.
(1) The viscosity should not be high so that it can smoothly enter a narrow pit and fissure.
(2) Reduction of material cost (3) Improving the long-term sustained sustained release concentration (release amount) of fluorine ions and improving the fluorine ion release concentration (recharge amount) after external fluorine ion incorporation.
(4) Excellent biocompatibility

  In particular, the GIC sealant material effectively penetrates into the pits and fissures that are difficult to penetrate deeply into the crevice, in order to effectively prevent dental caries and effectively treat dental caries. It is extremely important to increase the sustained release amount of ions. This is because the GIC sealant material that has penetrated deeply into the narrow pit and fissure causes secondary caries suppression and antibacterial action by releasing (releasing) and taking up (recharging) fluorine ions. Moreover, it is extremely important to reduce material costs while realizing excellent characteristics from the application.

  The present invention has been developed for the purpose of achieving the above-mentioned object, and an important object of the present invention is that it can smoothly enter the pits and fissures of teeth, which are narrow gaps, and the amount of liquid can be reduced. High-quality materials that have high strength, increase the sustained release of fluorine ions, possess the original characteristics and advantages of GIC, and use inexpensive hydroxyapatite as the material. It is an object of the present invention to provide a glass polyalkenoate cement for dental foveal cleft sealing made of a chemically hardened GIC capable of significantly reducing costs.

The present invention relates to a GIC used for a glass polyalkenoate cement for sealing dental pits and fissures used for preventing caries by filling the pits and fissures. A mixture of hydroxyapatite and a mixture of hydroxyapatite and glass powder is added and mixed with a specific amount of reaction solution to achieve a viscosity and high strength that can smoothly penetrate into the crevice cleft, which is a narrow gap between teeth. Realizing and using cheaper hydroxyapatite, increasing the sustained release amount of fluorine ions, filling the pits and fissures, and curing them quickly.

The glass polyalkenoate-based cement for sealing dental pits and fissures, which is a chemical hardening type GIC of the present invention, has the following configuration in order to solve the above-mentioned problems.
(1) Fine particle hydroxyapatite having an average diameter of 0.1 μm or more and 100 μm or less, a compressive strength of 0.9 MPa or less, and a specific surface area per unit weight of 30 m ² / g or more is used.
(2) In the mixed powder containing hydroxyapatite and glass powder, the mixing amount of hydroxyapatite is 15% by weight to 50% by weight.
(3) An amount of reaction liquid in which P / L (weight ratio of mixed powder / reaction liquid), which is a weight ratio of the mixed powder of glass powder and hydroxyapatite and the reaction liquid, is 0.3 or more and less than 2, Added and mixed, chemically cured.

  The glass polyalkenoate cement for sealing dental pits and fissures according to the present invention can have an average hydroxyapatite diameter of 5 μm or more, and further can be 10 μm to 30 μm.

  In the glass polyalkenoate cement for sealing dental pits and fissures according to the present invention, the reaction solution is a solution mainly composed of polyacrylic acid, distilled water, and a carboxylic acid for chemical reaction for curing. Can do.

  Furthermore, the glass polyalkenoate cement for sealing dental pits and fissures according to the present invention can make the average particle size of the glass powder smaller than that of hydroxyapatite. For example, the average particle size of the glass powder is 1 μm to 30 μm. be able to. Furthermore, the chemically hardened glass polyalkenoate cement for sealing dental pits and fissures according to the present invention is such that, in the particle size distribution of the glass powder, the proportion of the powder having a particle size of 10 μm or more is 20% or less. It can be used to penetrate more smoothly than a narrow crevice pit.

In addition to eliminating all the disadvantages of photo-curing GIC, the chemical-curing dental pit and fissure sealing glass polyalkenoate cement of the present invention is a conventional chemical-curing GIC sealant material. It was not possible to achieve high strength and smoothly penetrated into the crevice crevice with a narrow gap while increasing the sustained release amount of fluorine ions and using inexpensive hydroxyapatite. Realizes the ideal feature of being able to cure quickly.
The chemical hardening type GIC of the present invention uses a specific hydroxyapatite having a low crystallinity with a compressive strength of 0.9 MPa or less and a specific surface area of 30 m ² / g or more. Add a reaction solution in an amount that makes P / L (mixed powder / reaction solution weight ratio) of 0.3 or more and less than 2 as the weight ratio of the mixed powder of hydroxyapatite and the reaction solution. Because.

  FIG. 1 is a graph showing the release (release) amount of fluorine ions between the GIC (curve B) previously developed by the inventor described in Patent Document 2 and the GIC sealant material (curve A) of the present invention. is there. The GIC of the curve A and the curve B has the same amount of hydroxyapatite mixed in the mixed powder as 32% by weight. The release (release) of ions is about 35% more than that of GIC of Patent Document 2, and a large amount of fluorine ions are released to produce an excellent secondary caries inhibitory effect and antibacterial action.

In FIG. 1, the release (release) of fluorine ions is measured as follows.
A kneaded cement is filled in an acrylic disk-shaped mold having a diameter of 10 mm and a thickness of 2 mm, and pressed with a load of 500 g through celluloid strips and a slide glass. After 10 minutes at room temperature, the sample is removed from the mold and stored for 50 minutes at a temperature of 37 ° C. and a humidity of 100%. The sample is then immersed in 10 ml of distilled water and stored at 37 ° C. for 23 hours. Thereafter, a sample is taken out to obtain an eluate. The amount of fluorine eluted in the eluate is measured with an ion meter connected to a composite electrode. The sample taken out is wiped lightly and again immersed in 10 ml of fresh distilled water. In order to evaluate the reuptake ability of fluorine, after the measurement on the seventh day, the sample was immersed in 10 ml of NaF aqueous solution adjusted to 9000 ppmF for 5 minutes, taken out, washed with 5 ml of distilled water, lightly wiped off water, and then 10 ml of distilled water. Immerse in water and measure the amount of elution of fluorine every 24 hours until the 14th day.

Further, FIG. 2 shows the amount of release (release) of fluorine ions of the glass polyalkenoate cement of the present invention. In this figure, P / L (weight ratio of mixed powder / reaction liquid) is 1.2 and 1.6.
Curve A is 28% by weight of HAp and 1.2 P / L ratio,
Curve B shows the HAp mixing amount of 28% by weight and the P / L ratio of 1.6.
Curve C has a HAp mixing amount of 0 wt% and a P / L ratio of 1.2, and curve D has a HAp mixing amount of 0 wt% and a P / L ratio of 1.6. .

In FIG. 2, the amount of released (released) fluorine ions is measured as follows.
A kneaded cement is filled in an acrylic disk-shaped mold having a diameter of 10 mm and a thickness of 2 mm, and pressed with a load of 500 g through celluloid strips and a slide glass. After 10 minutes at room temperature, the sample is removed from the mold and stored for 50 minutes at a temperature of 37 ° C. and a humidity of 100%. The sample is then immersed in 8 ml of distilled water and stored at 37 ° C. for 23 hours. Thereafter, the sample is taken out and washed with 2 ml of fresh distilled water on the immersed distilled water to obtain a total of 10 ml of eluate. The amount of fluorine eluted in the eluate is measured with an ion meter connected to a composite electrode. The sample taken out is wiped off lightly and immersed in 8 ml of fresh distilled water again, and measurement is performed every 24 hours until 30 days and then every 90 days until 5 days.

  The glass polyalkenoate-based cement for sealing dental pits and fissures of the present invention reacts quickly with the HAp tooth structure at the interface and bonds strongly and hardly. The present invention does not harden the GIC by adding hard HAp as a filler. HAp to be added is made into specific fine particles with low compressive strength, that is, low crystallinity, and the specific surface area is increased, so that fine particles of HAp and GIC react quickly so that the teeth react quickly with GIC. To cure. In particular, since the GIC of the present invention uses HAp having low crystallinity and a large specific surface area, the release (release) and uptake (recharge) of fluorine ions are effective, and the sustained release amount of fluorine ions is large. Further, since a large amount of the reaction solution is used, the reaction proceeds to the inside of the particulate HAp, and the HAp and GIC are bonded in a uniform matrix to be quickly cured. Further, by using HAp having low crystallinity and a large specific surface area, the reactivity with GIC is improved, and the curing time is further shortened to be cured quickly.

  The glass polyalkenoate-based cement for sealing dental pits and fissures of Example 1 described below of the present invention has low crystallinity and is very inexpensive as 1/10 of HAp used for GIC of Reference 2. , Smoothly penetrate into the narrow pits and fissures, harden quickly, and increase the amount of sustained release of fluoride ions.

Since the glass polyalkenoate cement for sealing dental pits and fissures according to the present invention hardens quickly by a chemical reaction, the following (a) to () required for a GIC sealant material compared to a photo-curing resin: The excellent characteristics described in f) are also realized.
(A) Secondary caries inhibitory effect and antibacterial action by release (release) and uptake (recharge) of fluorine ions.
(B) Tooth adhesion (chemical adhesion) that does not require tooth surface treatment (acid etching).
(C) Compared to a photo-curing resin, it achieves low irritation to the dental pulp and high biocompatibility. This is because unstimulated hydroxyapatite is added to unstimulated GIC.
(D) It has a thermal expansion coefficient approximating that of the tooth.
(E) Mechanical strength is comparable to photocuring GIC.
(F) It cures to a clinically effective level in a short time of 15 minutes or less at room temperature.

  Furthermore, in recent years, the concept of Minimal Intervention (MI) has been spreading worldwide in the dental field, and the frequency of use of glass polyalkenoate cement for sealing dental pits and fissures with high tissue compatibility has increased. The invention can meet such worldwide demand.

It is a graph which shows the release amount of the fluorine ion of this invention and GIC of patent document 2. FIG. It is a graph which shows the release amount of the fluorine ion of the glass polyalkenoate-type cement of this invention. It is a particle size distribution figure of the glass powder for GIC type sealants used for the example of the present invention. It is an electron micrograph of the glass powder for GIC type sealants used for the example of the present invention. It is an electron micrograph which shows the surface state of HApS used for the Example of this invention. It is an electron micrograph which shows the surface state of HApS used for the Example of this invention. It is an electron micrograph which shows the internal state of HApS used for the Example of this invention. It is an electron micrograph of the fracture surface of the GIC type sealant material obtained in Example 1 of the present invention. It is an electron micrograph of the fracture surface of the GIC type sealant material obtained in Example 1 of the present invention. 4 is an electron micrograph showing the surface state of HAp100f used in Comparative Example 1. FIG. 4 is an electron micrograph showing the internal state of HAp100f used in Comparative Example 1. It is a graph which shows the three-point bending strength of Examples 1, 2 and Comparative Examples 2, 3. 6 is a graph showing a release amount of fluorine ions of GIC in Comparative Example 2.

The embodiment of the present invention will be described in detail as follows.
The glass polyalkenoate cement for sealing dental pits and fissures according to the present invention is a chemical hardening type GIC sealant material in which HAp is blended with a powder component. The present GIC sealant material, which is a glass polyalkenoate cement for sealing dental pits and fissures, is a GIC glass powder such as aluminosilicate glass, a powder composed of HAp powder, and a GIC reaction solution such as an aqueous polycarboxylic acid solution. Consists of. Furthermore, the present GIC sealant can be developed in both of a hand kneading method in which powder and liquid are kneaded by hand and a capsule method in which powder and liquid are put into a capsule and automatically kneaded by a machine.

[GIC sealant glass powder]
The glass powder preferably has an average particle size of 1 μm to 30 μm. Further, as the glass powder, a glass powder having a particle size distribution of 20 μm or less, more preferably 10% or less, is used in the particle size distribution. The glass polyalkenoate-based cement using this glass powder has a feature that it can penetrate deep into narrow pits and fissures. However, as the glass powder, a wide variety of commercially available glass powders for chemically curing GIC can be used.

[Reaction solution for GIC sealant]
As the reaction solution, a solution containing polyacrylic acid, distilled water, a carboxylic acid for chemical reaction for curing, and the like as main components is used. However, any carboxylic acid that is already commercially available as a GIC reaction solution and that will be developed as a GIC reaction solution can be used for this reaction solution.

[Hydroxyapatite]
The GIC sealant of the present invention contains a specific HAp. The addition of HAp is in the form of fine particles in consideration of the sustained release (release) and uptake (recharge) of fluorine ions, the curing time of GIC, the difference in thermal expansion coefficient between GIC and tooth, biocompatibility, etc. A porous HAp [Ca10 (PO ₄ ) ₆ (OH) ₂ ] having a specific average diameter and compressive strength and low crystallinity and having a specific surface area of 30 m ² / g or more is used.

  Further, as this HAp, one having a compressive strength of 0.9 MPa or less, preferably larger than 0.5 MPa and smaller than 0.9 MPa is used. HAp increases in compressive strength as crystallinity increases. The GIC developed by the present inventor and described in Patent Document 2 is used for filling in the cavity of the cavity, and HAp having higher crystallinity than the HAp used in the present invention is used. And glass powder were reacted quickly at the boundary to improve the mechanical strength.

On the other hand, the GIC of the present invention was developed as a sealant for sealing healthy pits and fissures, and it contains a large amount of an inexpensive porous HAp with low compressive strength and low crystallinity. In the course of the reaction, the reaction liquid is infiltrated into the voids of the porous empty HAp and uniformly cured to the inside, so that it is hardened quickly. As the HAp having low crystallinity used for the GIC sealant material of the present invention, an inexpensive material commercially available as a cosmetic material or an adsorbent can be used. For example, HApS manufactured by Taiyo Kagaku Sangyo with an average particle diameter of 21 μm, a specific surface area of 42 m ² / g, a compressive strength of 0.6, and an average pore diameter of 25 nm, which is commercially available as an additive for dentifrice, can be used. However, this HAp is extremely inexpensive at 1/10 compared to the HAp described in Patent Document 2. While using such inexpensive HAp, the glass polyalkenoate cement of the present invention realizes extremely excellent properties as a GIC sealant material.

  Further, the glass polyalkenoate-based cement of the present invention has a large amount of reaction solution, that is, P / L (mixed powder / weight of reaction solution) which is the weight ratio of the mixed powder of glass powder and hydroxyapatite to the reaction solution. The ratio) is set to 0.3 or more and less than 2 so that the reaction solution and the cement substrate component can quickly penetrate into the voids of HAp having low crystallinity.

  P / L (weight ratio of the mixed powder / reaction liquid) is set to less than 2 lower than that filled in the recess so as to obtain a preferable fluidity as a sealant material immediately after kneading. However, if it is too low, the flow is too good and the curing time is extended, so that the operability is deteriorated and the strength is lowered, which is not preferable. Therefore, P / L (weight ratio of mixed powder / reaction liquid) is 0.3 or more. As the liquid component, a conventional GIC liquid is used, and P / L (weight ratio of mixed powder / reaction liquid) is set to 0.3 or more and less than 2 in order to lower the viscosity and improve the fluidity.

The glass polyalkenoate cement for sealing dental pits and fissures of the present invention undergoes a curing reaction as follows.
(1) When aluminosilicate glass, which is a glass powder of the powder component, reacts with the polyalkenoic acid (mostly polyacrylic acid) in the reaction solution by kneading, metal ions (Al ³⁺ , Ca ²⁺ , Sr) are reacted from the glass. ²⁺ ) and fluoride ions simultaneously release Ca ²⁺ from the HAp, which migrates to the liquid layer and precipitates as a valence anion hydrated gel. At the same time, silica gel depleted of ions is produced in the outer layer of the glass powder.

(2) Next, part of the silica gel and hydrated gel in the generated cement mud penetrates into the voids of the porous HAp due to the adsorption force of HAp having a low crystallinity and a large specific surface area.
(3) Polyacrylic acid also enters the surface of the HAp molecule by adsorption, and causes phosphate migration or substitution on the HAp crystal surface.
(4) Furthermore, the free carboxyl group present in the adsorbed cement mud and HAp are hydrogen-bonded. Thereafter, the hydrogen bond is replaced with an ionic bond, and is replaced with a cation supplied from glass powder or HAp.
It is polyalkenoic acid polyelectrolyte that plays an important role in this reaction (adhesion between the cement matrix and the HAp crystal), and its role is to crosslink the interface between the cement matrix and the HAp crystal.
That is, polyacrylate ions are generated and ionic bonds are formed with calcium ions.
(5) As part of the subsequent complex ion exchange, calcium ions leave the HAp with the phosphate, and an intermediate layer of calcium phosphate, aluminum phosphate, and polyacrylate is at the cement matrix and HAp crystal interface. It is formed.

  Note that the mechanical strength of HAp decreases even if the average diameter is small or large. In addition, since the curing time becomes longer if it is too small, the average diameter is 0.1 μm to 100 μm, preferably 5 μm or more, more preferably in consideration of the release amount of fluorine ions, mechanical strength, curing time, fluidity and the like. Is 10 μm to 30 μm. Furthermore, HAp having a specific surface area of 30 m <2> / g or more is used to improve reactivity.

[HAp blending amount]
In consideration of the fact that the fine particle HAp is mixed and mixed to increase the mechanical strength of the matrix holding the GIC glass component particles in the cured product and increase the release of fluoride ions, The amount of HAp added and mixed is 15% to 50% by weight with respect to the mixed powder, desirably about 15% to 30% by weight, and optimally about 20% to 28% by weight.

  Increasing the amount of HAp added can increase fluorine ion release. However, the amount of HAp added and mixed affects the bending strength in the cured state, and the bending strength decreases if the amount of added and mixed is too large or too small. Therefore, the amount of HAp added and mixed is set to 15% by weight to 50% by weight with respect to the mixed powder in consideration of both fluorine ion release and bending strength.

[Chemical curing process]
(1) Add HAp to the GIC sealant powder and mix it thoroughly.
(2) Next, a reaction solution for GIC sealant is added to and mixed with the mixed powder of GIC sealant powder and HAp and kneaded sufficiently. At this time, P / L (weight ratio of mixed powder / reaction liquid), which is a ratio of the mixed powder and the reaction liquid for GIC, is set to 1.2 or 1.6. However, the weight ratio of P / L may be 0.3 or more and less than 2.
(3) The obtained kneaded material begins to cure, and is cured to a desired mechanical strength when it is allowed to stand for about 3 to 30 minutes, preferably about 5 to 10 minutes at room temperature, body temperature, etc. .

  Examples of the present invention will be given below to specifically explain the configuration and effects of the present invention. However, the present invention is not limited to these examples.

[Example 1]
In the following steps, a glass polyalkenoate cement for dental pit and fissure sealing, which is a chemical hardening type GIC to which HAp is added, is hardened.
GIC reaction liquid and GIC powder include commercially available chemically cured GIC “Fuji III [manufactured by GC Corporation (Japan)]” glass powder (hereinafter referred to as “III powder”) and reaction liquid (hereinafter referred to as “III powder”). (Denoted as “III liquid”). FIG. 3 shows the particle size distribution of the III powder, and FIG. 4 shows an electron micrograph of the III powder.

  As the HAp added to the glass powder, 1 HApS manufactured by Taiyo Kagaku Sangyo, which is commercially available as an additive for dentifrice, is used. HApS has an average particle diameter of 21 μm, a specific surface area of 42 m 2 / g, a compressive strength of 0.6, and an average pore diameter of 25 nm. Electron micrographs of this HApS are shown in FIGS. FIG. 5 shows the surface state of HApS, FIG. 6 shows a further enlarged surface state, and FIG. 7 shows the internal state of HApS. In this HApS, fine particles of 0.2 μm to 0.3 μm are aggregated in a state where fine voids are formed inside.

A trial powder is prepared by adding 28% by weight of the above-mentioned HApS and 72% by weight of glass powder (III powder).
Next, the III powder is added to the prototype powder so that the P / L (mixed powder / reaction solution) is 1.2 by weight, and then the mixture is kneaded to prepare a sample.

The sample is cured as follows.
(1) IX powder and HAp powder are mixed for 1 minute by an automatic mixer (vortex).
(2) A separating material (SURE SEP) is applied to a stainless steel mold (3.0 mm × 3.0 mm × 25.0 mm) with a small brush, and then thinned with air.
(3) The mixed powder and the liquid III are kneaded for 45 seconds on a paper kneading board using a plastic spatula.
(4) Then, this is put into a syringe (like a syringe) and injected into a mold. At this time, press with a plugger that does not generate bubbles or gaps, and place it on a glass plate.
(5) Press with a weight (500 g) through transparent strips and leave at room temperature for 10 minutes.
In this state, the GIC sealant material is cured.
(6) A sample is taken out from the mold and allowed to stand for 50 minutes in a state of 37 ° C. and humidity of 100% (wrap the sample with filter paper soaked in water) for 50 minutes.
This step is a step of applying stress as an environment in the mouth where the GIC is used.

  The GIC sealant material cured in the above steps smoothly penetrates into a narrow pit and fissure in an uncured state and cures quickly to release (release) a large amount of fluorine ions. The amount of released (released) fluorine ions is shown by curve A in FIG.

Further, FIGS. 8 and 9 show electron microscopes of the fracture surface of the GIC sealant material. As shown in the electron micrograph of FIG. 7, the reaction liquid penetrates into the HApS in the cured GIC sealant material and is cured.
Further, the three-point bending strength of this GIC sealant material is shown in FIG.

[Example 2]
The GIC sealant material is cured in the same manner as in Example 1 except that the P / L ratio is 1.2 to 1.6.
The GIC sealant material cured in the above steps also smoothly penetrates into the narrow pits and fissures in an uncured state, and quickly cures to release (release) a large amount of fluorine ions. The amount of released (released) fluorine ions is shown by curve B in FIG.

[Example 3]
The GIC sealant material is cured in the same manner as in Example 1 except that the amount of HApS added is 32% by weight.
The GIC sealant material cured in the above steps also smoothly penetrates into the narrow pits and fissures in an uncured state, and quickly cures to release (release) a large amount of fluorine ions. The amount of released (released) fluorine ions is shown by curve A in FIG.

[Comparative Example 1]
For comparison, the GIC is cured in the same manner as in Example 3 except that HApS is as follows.
HAp is an extremely finely pulverized HAp100 commercially available from Taihei Chemical Industry Co., Ltd. (Japan) as a bone filler with an average particle size of 200 μm using an automatic mortar (Electric Dancing Mill, Nippon Ceramic Science Co., Ltd.). And having an average particle size of 11 μm is used. Electron micrographs of this HAp100f are shown in FIGS. FIG. 10 shows the surface state of HAp100f, and FIG. 11 shows the internal structure of HAp100f. As shown in the electron micrograph of FIG. 10, HAp100f has ultrafine particles of several nanometers to several hundred nanometers attached to its surface and has a compressive strength of 1 MPa.

  The amount of released (released) GIC fluorine ions cured in the above steps is shown by curve B in FIG. In this GIC, although the same amount of HAp as in Example 3 is added, the amount of released (released) fluorine ions is considerably smaller than that in Example 3 shown by curve A in FIG.

  When point analysis is performed using the energy dispersive X-ray analyzer for the elements contained in the GIC obtained in Comparative Example 1 and the GIC sealant material obtained in Example 1, the following Table 1 is obtained. .

  The elements contained in HAp are Ca, P, O and H. The main contained elements of the GIC of Comparative Example 1 and the GIC sealant material of Example 1 obtained by using this are C, O, F, Al, Si, P, and Sr. When a point analysis was performed on the central part of the HAp added to the GIC by EDS, the GIC component was detected, which revealed that the HAp adsorbs the GIC component. Furthermore, there is a difference in the amount of various GIC elements adsorbed depending on the type of HAp, and it is recognized that HApS has a higher ratio of F and Si than HAp100f. In addition, the HAp-derived element had a lower Ca value (%) than HAp100f, indicating that HApS adsorbs more GIC components inside the HAp. The greater the content of F adsorbed in the HAp, the more the fluorine ion sustained release amount from the GIC, and the more the Si amount adsorbed in the HAp, the better the strength of the GIC. From the above results, it can be seen that HAp added to GIC is more effective than HAp100f.

[Comparative Example 2]
For comparison, the GIC is cured with the P / L ratio set to 1.2 in the same manner as in Example 1 except that HApS is not added. The amount of fluorine ion released (released) by this GIC is shown by curve C in FIG. The 90-day fluoride ion release amount of Comparative Example 2 is 42% of the fluoride ion release amount of Example 1 (curve A in FIG. 2). Further, the three-point bending strength is shown in FIG. The 3-point bending strength of Comparative Example 2 is 58% inferior to that of Example 1.

[Comparative Example 3]
Also, without adding HApS, the GIC is cured at a P / L ratio of 1.6 in the same manner as in Example 2 except that. The amount of fluorine ion released (released) by this GIC is shown by curve D in FIG. The 90-day fluorine ion release amount of Comparative Example 3 is 61% of the fluorine ion release amount of Example 2 (curve B in FIG. 2). Further, the three-point bending strength is shown in FIG. The three-point bending strength of Comparative Example 3 is inferior by 40% compared to Example 2.

[Comparative Example 4]
Further, the glass powder is a glass powder of a commercially available chemical curing type GIC “FujiIX [manufactured by GC Corporation (Japan)]”, the reaction solution is changed from the III solution to the IX reaction solution, and the P / L ratio is 1. The GIC is cured in the same manner as in Example 1 except that the amount is 2 to 3.6 and the addition amount of HApS is 10% by weight.

  This GIC is not cured, and cannot smoothly enter the crevice cleft with a narrow gap, and in the cured state, fluorine releases (releases) ions considerably. FIG. 13 shows the release (release) amount of fluorine ions of this GIC. In this GIC, although the same HAp as in Example 1 is added, the amount of released (released) fluorine ions is considerably smaller than that in Example 3 indicated by curve A in FIG.

The glass polyalkenoate cement for sealing dental pits and fissures is effective for preventing caries in the dentistry field. In particular, it is effective as a sealant material for the pits and fissures in all parts of deciduous teeth and permanent teeth.

Claims (7)

Fine particles of hydroxyapatite having an average diameter of 0.1 μm or more and 100 μm or less, a compressive strength of 0.9 MPa or less, and a specific surface area per unit weight of 30 m ² / g or more, and this hydroxyapatite mixed A mixed powder containing hydroxyapatite and glass powder, wherein the mixed amount of hydroxyapatite is 15 wt% to 50 wt%,
Further, the reaction solution in such an amount that P / L (mixed powder / reaction solution weight ratio), which is a weight ratio of the mixed powder of the glass powder and the hydroxyapatite and the reaction solution, is 0.3 or more and less than 2. A glass polyalkenoate- based cement for sealing dental pits and fissures, which is used for the prevention of caries by being filled into pits and fissures that are added and mixed and chemically hardened.   The glass polyalkenoate-based cement for sealing dental pits and fissures according to claim 1, wherein the hydroxyapatite has an average diameter of 5 µm or more.   The glass polyalkenoate-based cement for sealing dental pits and fissures according to claim 2, wherein the hydroxyapatite has an average diameter of 10 µm to 30 µm.   4. The chemical-curing type dental small body according to claim 1, wherein the reaction liquid is a solution mainly composed of polyacrylic acid, distilled water, and a carboxylic acid for chemical reaction for curing. Glass polyalkenoate cement for sealing fissures.   5. The chemically hardened glass polyalkenoate cement for sealing dental pits and fissures according to claim 1, wherein the glass powder has an average particle size smaller than that of hydroxyapatite.   The glass polyalkenoate cement for chemically curing dental pits and fissures according to any one of claims 1 to 5, wherein the glass powder has an average particle size of 1 to 30 µm.   7. The glass polyalkeno for chemically curing dental pit and fissure sealing according to claim 1, wherein in the particle size distribution of the glass powder, the proportion of the powder having a particle size of 10 μm or more is 20% or less. Ate cement.