Dental etching agent

Abstract

To provide a dental etching agent that can suitably be used for a "selective enamel etching method" that performs etching and cleaning treatment only on parts of the enamel margin without demineralizing the dentin, the dental etching agent being easy to prepare, having good operability (ejectability from a syringe) when used by filling a syringe, and having shape retention properties that makes spreading thereof after ejection unlikely.SOLUTION: A powder comprising a water insoluble polymer is used as a thickener in a water insoluble polymer having an amino group known to function as a cationic thickener, 2.0-6.5 parts by mass of this mixture is blended with 100 parts by mass of an acid solution such as a phosphoric acid solution to form a viscous fluid which is used as a dental etching agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel dental etching agent, and more particularly to a novel dental etching agent used before dental restorative treatment. [Background technology]

[0002] Dental restorative materials used in dental treatment include direct restorative materials such as composite resins and indirect restorative materials such as metals and ceramics. When restoring living dental tissue, these dental restorative materials must be bonded to the dental tissue. However, the dental restorative materials themselves lack adhesive properties. Therefore, the surface of the dental tissue to be restored is typically treated (etched or decalcified) with an etching agent containing an aqueous solution of phosphoric acid, carboxylic acid, or citric acid (an acidic aqueous solution). This increases the adhesive area by forming fine irregularities on the surface, and the dental restorative material is then bonded using a dental adhesive. Etching agents are also used to etch non-cut tooth surfaces during loose tooth fixation and orthodontic treatment, to remove saliva, plaque, and other contaminants from the surface, and to clean the surface of indirect restorative materials.

[0003] However, etching agents can cause problems when the acid solution spreads from the application site, attacking healthy teeth, dental pulp, or even gums, and in some cases causing unnecessary pain to the patient. Also, excessive demineralization of dentin can cause postoperative pain.

[0004] Known techniques for preventing such problems include a technique of compounding carboxymethylcellulose sodium salt and / or highly dispersible silica to form a paste (see Patent Document 1), and a technique of compounding silica and a nonionic water-soluble polymer to increase viscosity (see Patent Document 2).

[0005] Furthermore, in recent years, the development of self-etching bonding agents with improved adhesion to dentin has made it possible to etch and clean only the enamel margins without demineralizing the dentin. This method is called the "selective enamel etching method," and in order to apply this method, there is a growing demand for etching agents that have the ability to retain their shape so that they do not flow out of the application area when applied directly to only a small area using a syringe equipped with a small-diameter nozzle tip.

[0006] As an etching agent with improved shape retention, Patent Document 3 discloses a dental pretreatment agent in which fumed silica is dispersed in an acidic aqueous solution, wherein the fumed silica has an average primary particle diameter of 5 to 100 nm and is dispersed while satisfying the following agglomerated secondary particle properties i) to iii) as measured by a laser diffraction scattering method: i) The volume average particle size of the agglomerated secondary particles is 5 to 50 μm ii) The volume percentage of agglomerated secondary particles with a volume particle size of 1 μm or less is 20% or less iii) The volume percentage of agglomerated secondary particles having a volume particle size of 100 μm or more is 5% or less.

[0007] According to Patent Document 3, when the etching agents described in Patent Documents 1 and 2 are used, increasing the viscosity can improve shape retention, but this reduces the ejection properties from a syringe. In contrast, the above etching agent (dental pretreatment agent) does not require excessive ejection pressure when ejected from a syringe, and it has sufficient viscosity, appropriate consistency, and shape retention even after being ejected from the syringe. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 53-36994 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-222642 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-63489 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in the dental etching agent (dental pretreatment agent) described in Patent Document 3, it is necessary to strictly control the primary particle size of the fumed silica to be added, the particle size distribution of the secondary aggregated particles, and the like. Therefore, in producing the agent, not only is it necessary to mix the components under strict condition control using a planetary centrifugal mixer, but also, for quality control of the product, it is necessary to check the dispersion state of the fumed silica secondary particles in the resulting mixture using a particle size distribution measuring device or the like, which imposes a heavy burden on production and quality control.

[0010] Therefore, an object of the present invention is to provide an etching agent that can be easily prepared without using fumed silica, which requires complicated control of the dispersion state, and that, when used (applied) using a syringe with a thin nozzle for application in, for example, a "selective enamel etching method," exhibits good shape retention after ejection without making the ejection pressure of the etching agent ejected from the syringe excessively high (heavy). [Means for solving the problem]

[0011] The present invention is intended to solve the above-mentioned problems, and a first aspect of the present invention is a dental etching agent comprising a viscous fluid containing 100 parts by mass of an acid aqueous solution and 2.0 to 6.5 parts by mass of a powder that functions as a cationic thickener and is made of a water-insoluble polymer having an amino group.

[0012] In the dental etching agent of the above form (hereinafter also referred to as "etching agent of the present invention"), it is preferable that the water-insoluble polymer has structural units represented by the following formulas (A), (B), and (C), and the proportion of the structural units represented by the following formula (A) in the entire water-insoluble polymer is 15 to 85 mass %. However, in the following structure, R 1 represents a hydrogen atom or a methyl group, and R 2 represents a linear alkyl group having 1 to 17 carbon atoms.

[0013] [ka]

[0014] The water-insoluble polymer powder preferably has a volume average particle size of 10 to 100 μm as measured by a laser diffraction scattering method.Moreover, the powder is preferably for use in etching enamel.

[0015] A second form of the present invention is a syringe-filled dental etching agent, which is provided in a state where the dental etching agent is filled in a syringe, and after a nozzle is attached, the dental etching agent is ejected from the nozzle and applied to a predetermined location on the enamel, characterized in that the dental etching agent filled in the syringe is the dental etching agent of the present invention for etching enamel.

[0016] The syringe-filled dental etching agent in the above form (hereinafter also referred to as "syringe-filled etching agent of the present invention") is preferably used by attaching a nozzle having an inner diameter of the nozzle projection hole within a range of 0.07 to 0.8 mm. [Effects of the Invention]

[0017] When the etching agent of the present invention is used (applied) using a syringe with a narrow nozzle, it can be ejected from the syringe without significantly increasing the ejection pressure, and the shape (form) after ejection can be easily maintained. Therefore, the etching agent ejected from the syringe is less likely to spread from the intended application site, and even if the intended site is narrow (minor), it is possible to pretreat (apply only to) the intended site. Furthermore, the powder functioning as a cationic thickener, which is made of a water-insoluble polymer used in the etching agent of the present invention, is available as a cationic thickener, and commercially available products can be used as is, so it can be easily prepared by simply mixing the respective components in the appropriate amounts according to the composition.

[0018] Furthermore, the syringe-filled dental etching agent of the present invention has the advantages of being easy to handle and having good shape retention after application, due to the use of the etching agent of the present invention as a dental etching agent filled in a syringe, and is therefore particularly suitable as a syringe-filled dental etching agent for selective enamel etching. DETAILED DESCRIPTION OF THE INVENTION

[0019] In the present invention, a water-insoluble polymer powder containing amino groups known to function as a cationic thickener is used. It is generally believed that thickening of aqueous compositions by the addition of a cationic thickener is due to a water-retention mechanism in which a strong positive charge is generated on the amino groups in the polymer through a neutralization reaction between the amino groups and an acid, resulting in ionic repulsion within the polymer molecules, causing the crosslinked polymer to swell and incorporate water molecules into the polymer molecules. However, as shown in Comparative Example 1 below, when a water-soluble polymer known as a cationic thickener is used, it is difficult to achieve both improved shape retention and suppressed discharge pressure increases. Therefore, the reason why the etching agent of the present invention exhibits the above-mentioned effects cannot be explained solely by the water-retention mechanism.

[0020] Although the present invention is not bound by any theory, it is presumed that the positively charged amino groups in the water-insoluble polymer produced by the neutralization reaction with the acid and the negatively charged oxygen atoms in the water trapped between the insoluble powder particles are attracted to each other by electrostatic force, resulting in the development of a type of cross-linked structure between the particles, strengthening the aggregation between the particles and retaining water between or within the particles (by capillary action or the above-mentioned water retention mechanism), thereby improving shape retention. Furthermore, the reason why the protrusion pressure is difficult to increase is thought to be that the bonding strength of the above-mentioned cross-linked structure is weak and easily (temporarily) collapses when pressure is applied.

[0021] The etching agent of the present invention and the syringe-filled etching agent of the present invention will be described in detail below. In this specification, unless otherwise specified, the expression "x to y" using numerical values ​​x and y means "greater than or equal to x and less than or equal to y." In such an expression, when a unit is assigned only to the numerical value y, the unit is also applied to the numerical value x.

[0022] 1. Etching agent of the present invention The dental etching agent of the present invention is characterized in that a specific amount of "powder that functions as a cationic thickener and is made of a water-insoluble polymer having multiple amino groups in its molecule" (hereinafter also referred to as "water-insoluble powdered cationic thickener") is dispersed in an acidic aqueous solution to form a viscous fluid. That is, the water-insoluble powdered cationic thickener is blended in an amount of 2.0 to 6.5 parts by mass per 100 parts by mass of the acidic aqueous solution.

[0023] Here, a water-insoluble polymer means a polymer in which, when 0.05 g of a powdery polymer (resin or polymeric substance) is dispersed in 100.0 g of water at 23.0°C, the entire amount does not dissolve, and at least a portion remains in an undissolved state, which can be visually confirmed.

[0024] The etching agent of the present invention is not particularly different from conventional etching agents except for the above points, and as the acid aqueous solution and other optional components, those that can be used in conventional etching agents can be used without any particular restrictions. Therefore, first, the water-insoluble powder cationic thickener will be explained in detail, then the other components and their blending amounts will be explained, and further, the preparation method and properties of the etching agent of the present invention will be explained.

[0025] (1) Water-insoluble powder cationic thickener The water-insoluble powder cationic thickener is not particularly limited as long as it is a powder composed of (fine) particles of a water-insoluble polymer having amino groups and functions as a cationic thickener. A polymer having amino groups typically has multiple amino groups in the polymer backbone, which neutralize with an acid in the presence of water, thereby acquiring a positive charge and exhibiting a thickening effect. In the present invention, the use of a water-insoluble polymer powder makes it possible to increase the viscosity at rest and provide shape retention without significantly increasing the viscosity under shear stress. Specifically, when used (applied) using a syringe with a narrow nozzle, it is possible to impart the property of being less likely to spread beyond the intended application site after ejection without increasing the ejection pressure when ejected from the syringe.

[0026] The amino group possessed by the water-insoluble polymer refers to -NH2, -NHR, or -NRR' (R and R' are substituents). Among these, it is preferable to have an -NRR' group which becomes a tertiary amine. Examples of water-insoluble polymers having an amino group include poly-N,N-dimethylallylamine, poly-N,N-diethylallylamine, and poly-N,N-diallylmethylamine.

[0027] From the viewpoints of availability and effectiveness, the water-insoluble polymer having an amino group is preferably a polymer having structural units represented by the following formulae (A), (B) and (C).

[0028] [ka]

[0029] In addition, R in the structural unit 1 means a hydrogen atom or a methyl group, and R 2 means a linear alkyl group having 1 to 17 carbon atoms.

[0030] When the structural unit (A) is mixed with an acid, it generates positively charged amino groups in the water-insoluble polymer, which electrostatically attract negatively charged oxygen atoms in the water trapped between the insoluble powder particles, forming a crosslinked structure between the particles and strengthening the aggregation between the particles. The proportion of the structural unit (A) in the water-insoluble polymer is preferably 15 to 85% by mass, more preferably 25 to 65% by mass, and even more preferably 30 to 55% by mass.

[0031] The water-insoluble polymer having the structural units represented by the formulas (A), (B) and (C) is described, for example, in JP-A-5-140531, and is also represented by the following formula (1) (where R 1 is a hydrogen atom or a methyl group, and R 2 is a linear alkyl group having 1 to 17 carbon atoms. Compounds having the structure shown in are commercially available.

[0032] [ka]

[0033] The water-insolubility of polymers having structural units represented by the formulae (A), (B), and (C) depends on the molecular weight; the larger the weight-average molecular weight, the higher the water-insolubility (the lower the water-solubility). Therefore, a polymer having a weight-average molecular weight that exhibits water-insolubility according to the definition of the present invention can be appropriately selected and used. For example, it is known that polymers having a structure represented by the formula (1) with a weight-average molecular weight of 5,000,000 are water-insoluble.

[0034] From the viewpoint of effectiveness, the water-insoluble polymer powder constituting the water-insoluble powder cationic thickener preferably has a volume-average particle diameter of 10 to 100 μm, particularly 30 to 50 μm, as measured by laser diffraction scattering. The volume-average particle diameter of the etching agent can be measured using a particle size analyzer (e.g., Beckman Coulter LS13 320) for a sample prepared as follows: First, 2.0 g of the etching agent containing the water-insoluble polymer dispersed therein and 18.0 g of ethanol are mixed, placed in a 20 cc cylindrical glass container (e.g., a screw tube), and shaken thoroughly (without ultrasonic treatment) until uniform dispersion is visually confirmed. Furthermore, the inventors' studies have confirmed that the volume-average particle diameter of the water-insoluble polymer does not change when the dental etching agent and ethanol are mixed by shaking.

[0035] To achieve the above-mentioned effects, the blending amount of the water-insoluble powder cationic thickener in the dental etching agent of the present invention should be 2.0 to 6.5 parts by mass of the water-insoluble polymer having multiple amino groups per 100 parts by mass of the total mass of the acid and water in the acid aqueous solution described below. In consideration of better shape retention (shape retention) and ejection properties, the blending amount is more preferably 2.0 to 5.5 parts by mass, and even more preferably 3.0 to 5.0 parts by mass.

[0036] (2) Acid aqueous solution The acid aqueous solution has the function of decalcifying teeth and the function of facilitating removal of stains by decomposing or dissolving them, etc. The acid aqueous solution is not particularly different from those used in conventional dental etching agents, and aqueous solutions of phosphoric acid or carboxylic acid can be suitably used.

[0037] The phosphoric acid may be any acid formed by hydration of diphosphorus pentoxide, including metaphosphoric acid, pyrophosphoric acid, orthophosphoric acid, triphosphoric acid, and tetraphosphoric acid. Among these, orthophosphoric acid (H3PO4) is preferred. Other examples include phosphate group-containing polymerizable monomers such as 2-methacryloyloxyethyl dihydrogen phosphate, bis(2-methacryloyloxyethyl)hydrogen phosphate, and 10-methacryloyloxydecyl dihydrogen phosphate.

[0038] Examples of carboxylic acids include carboxylic acids having 2 to 4 carbon atoms. Specific examples include acetic acid, propionic acid, malonic acid, maleic acid, and succinic acid. Also included are carboxylic acid group-containing polymerizable monomers such as (meth)acrylic acid and 11-(meth)acryloyloxy-1,1-undecanedicarboxylic acid.

[0039] In addition to phosphoric acid or carboxylic acid, inorganic acids such as nitric acid, sulfuric acid, or hydrofluoric acid, and organic acids such as acidic group-containing polymerizable monomers (e.g., 2-methacrylamido-2-methylpropanesulfonic acid) can also be used. These acids may be used alone or in combination of two or more.

[0040] It is preferable that the water in the acid aqueous solution be free from harmful impurities by distillation, filtration, ion exchange, or the like.

[0041] The acid concentration in the acid aqueous solution is not particularly different from that of conventional dental etching agents, and the amount of acid is usually 5 to 80 parts by mass, preferably 15 to 70 parts by mass, and particularly preferably 20 to 55 parts by mass, when the total amount of acid and water is 100 parts by mass.

[0042] (3) Other ingredients The dental etching agent of the present invention may contain thickeners other than the water-insoluble powder cationic thickener, as long as they do not adversely affect the effects of the present invention. Suitable thickeners include organic thickeners such as polymethyl methacrylate (PMMA), polyethylene glycol (PEG), polymethyl methacrylate-polyethyl methacrylate copolymer, ethylene-vinyl acetate copolymer, and styrene-butadiene copolymer, as well as inorganic thickeners composed of inorganic powders such as fumed silica, silica-zirconia particles, quartz, and fluoroaluminosilicate glass. Organic-inorganic composite thickeners obtained by mixing these inorganic powders with polymerizable monomers, polymerizing the mixture, and pulverizing the mixture can also be used. These other thickeners can be used alone or in combination of two or more. The amount of the other thickener can be determined appropriately depending on the intended use. The amount of the other thickener can be determined appropriately depending on the intended use, but it is preferably 5 parts by weight or less, and more preferably 2 parts by weight or less, based on 100 parts by weight of the total amount of acid and water. It should be noted that there is no particular need to use special fumed silica such as that described in Patent Document 3.

[0043] The dental etching agent of the present invention may also contain the following components (additives) as needed: colorants such as various natural dyes and tar dyes, fluorescent agents, or flavoring agents; antibacterial substances such as benzalkonium chloride and cetylpyridinium chloride; medicinal ingredients such as chlorhexidine that inhibit the activity of proteolytic enzymes such as matrix metalloproteinase; various radical polymerizable monomers, and various chemical and photopolymerization catalysts. The amount of these additives may be determined appropriately depending on the purpose, but is typically about 0.01 to 10 parts by mass when the total amount of acid and water is 100 parts by mass.

[0044] (4) Preparation method and characteristics of the etching agent of the present invention The etching agent of the present invention can be suitably prepared by mixing predetermined amounts of each component using a stirring and mixing device such as a magnetic stirrer, stirring blade, or planetary mixer. The acid, water, water-insoluble powdered cationic thickener, and other additives, if necessary, can usually be simultaneously added to the stirring and mixing device. However, when phosphoric acid is used as the acid, it is preferable to prepare an aqueous phosphoric acid solution in advance and mix it with the other components. This is because phosphoric acid is difficult to handle due to its high hygroscopicity. In this case, the concentration of the aqueous phosphoric acid solution is preferably 70 to 90% by mass.

[0045] The dental etching agent of the present invention is acidic, and its pH can be adjusted appropriately depending on the specific application (purpose) of use. For example, when the purpose is decalcification and cleaning of tooth tissue, a pH of 0 to 5 is preferable, and when the purpose is to dissolve and remove smear layers, etc., as a pretreatment for tooth bonding operations, a pH of 0 to 3 is particularly preferable. Furthermore, when used as an acid etching agent to dissolve tooth tissue, a pH of 0 to 1 is preferable.

[0046] When using the etching agent of the present invention, for example, the dental etching agent is first applied to the treatment surface, such as the missing portion of a patient's tooth or the surface of the uncut tooth, using a brush or sponge or directly supplied from a syringe. After allowing it to act for several seconds to several minutes, the treatment surface is washed and dried, and then a restorative material, such as an adhesive or composite resin, is applied or filled to the treatment surface. The etching agent of the present invention may be applied not only to tooth enamel but also to dentin, which exists beneath the enamel. Furthermore, it can also be used for cleaning dental restorative materials, such as those made of metal, ceramic, or composite resin. By using the dental etching agent according to the embodiment of the present invention, only the treatment area requiring extremely small pretreatment can be cleaned or etched, and then the tooth can be effectively restored.

[0047] The dental etching agent of the present invention is a viscous fluid with moderate viscosity and good shape retention, making it suitable for pretreatment of narrow (micro) areas. Such viscoelastic properties can be evaluated as "consistency." Here, "consistency" is used in the dental field as an index for evaluating the shape retention of a viscous fluid, and is evaluated based on the degree of spread when a predetermined load is applied to a predetermined amount of viscous fluid. Essentially, for the purpose of relative comparison between different types of viscous fluids, it is a physical property value under certain unified evaluation conditions (e.g., amount, load, load application method, etc.) (rather than an absolute physical property value such as density). However, in the dental field, it is often used as an index for determining the quality of shape retention. In the present invention, the value measured by the following method is referred to as "consistency."

[0048] Specifically, (1) first, prepare two polyester sheets (e.g., Tokyo Glass Instruments Co., Ltd., product name Polyester Film, thickness 0.1 mm) cut into 5 cm x 5 cm squares. (2) Next, place 0.1 g of dental etching agent near the center of one of the sheets placed on a horizontal surface, taking care to avoid the inclusion of air bubbles, etc., so that it forms a circle with a diameter of 10 mm or less. Then, gently place the other sheet on top of it (overlapping them so as not to add weight). (3) Then, place a rectangular plate-shaped weight with a horizontal surface measuring 6 cm in length and width on top of the other sheet, adjusted so that the total weight with the other sheet is 50 g, so that its surface is in contact with the top surface of the other sheet. Note that, even during this process, be careful not to apply excessive pressure with your hands (do not apply a weight of more than 50 g). (4) After leaving the sheet in this state for 10 seconds, the weight is removed by lifting it upward without applying any extra load. The longest distance (mm) of the diameter of the thin film of dental etching agent that spreads out in an approximately circular shape while sandwiched between the two sheets is measured as the major axis, and the diameter of the thin film of dental etching agent on the line passing through the center of the major axis and intersecting the major axis at right angles is measured as the minor axis. (5) The average value of the major axis and the minor axis, i.e., (major axis + minor axis) / 2 (mm), is taken as the consistency.

[0049] The dental etching agent of the present invention typically has a consistency of 8.0 to 24.0 mm, which provides good shape retention and prevents excessive discharge when discharged from a syringe. When the consistency exceeds 24.0 mm, the agent tends to be unable to maintain good shape retention, while when the consistency is below 8.0 mm, the agent tends to be less dischargeable. To maintain better shape retention and dischargeability, the consistency is preferably 12.0 to 21.0 mm, and more preferably 18.0 to 21.0 mm.

[0050] 2. Syringe-filled etching agent of the present invention The etching agent of the present invention is usually provided in a container such as a syringe, eye dropper, tube, or bag, but is preferably provided as a syringe-filled dental etching agent of the present invention because the effects of the present invention are most effectively exhibited when applied to the "selective enamel etching method." That is, the etching agent of the present invention is preferably provided as a syringe-filled dental etching agent for use in enamel etching, and is provided in a state filled in a syringe, to which a nozzle is attached and from which the dental etching agent is ejected and applied to a predetermined location on the enamel.

[0051] The syringe can be the same as that used for conventional syringe-filled etching agents, without any particular limitations. Regarding the nozzle, it is preferable to use a single-use, replaceable nozzle tip that is attached to the nozzle when in use. Syringes that are highly airtight even after long-term storage are preferred from the viewpoint of storage stability, and lure-lock types are suitable because they can prevent the contents from scattering due to unexpected detachment of the nozzle tip. The nozzle tip can be made of metal or plastic, and the length of the discharge needle portion of the nozzle tip is usually about 2 to 50 mm. The inner diameter of the nozzle tip does not have to be constant, and a nozzle tip with a variable inner diameter, such as a tapered structure, can also be used. Furthermore, the inner diameter of the nozzle tip used in the syringe-filled etching agent of the present invention is preferably 0.8 mm or less {gauge size in accordance with ISO09626 is 18 G or more (inner diameter is 18 G or less)}, more preferably 0.5 mm or less (gauge size in accordance with ISO09626 is 22 G or more (inner diameter is 22 G or less), and even more preferably 0.3 mm or less (gauge size in accordance with ISO09626 is 24 G or more (inner diameter is 24 G or less). The lower limit of the inner diameter of the tip is not particularly limited, but is 0.07 mm in consideration of normal use.

[0052] Even when discharged from a syringe equipped with such a nozzle tip, the etching agent of the present invention does not exert excessively heavy discharge pressure. Furthermore, even after being discharged from the syringe, it maintains sufficient viscosity, suitable consistency, and shape retention, making it difficult to spread beyond the intended application site, allowing for pretreatment of only the intended site, even when the target site is small. For example, when pretreating the enamel margin of a narrow cavity, if the etching agent is applied directly from a syringe equipped with a small inner diameter tip, the applied etching agent maintains its shape as applied as much as possible and is unlikely to spread beyond the application site. The margin may be 2 mm or less, 1.5 mm or less, or even 1 mm or less. [Example]

[0053] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. First, raw materials used in the examples and comparative examples will be described.

[0054] (1) Acid aqueous solution The following acids were dissolved in distilled water:

[0055] Phosphoric acid: 85% by weight phosphoric acid (orthophosphoric acid) aqueous solution Acetic acid Malonic acid.

[0056] (2) Thickener <Water-insoluble powder cationic thickener> Coscut GA468 {manufactured by Osaka Organic Chemical Industry Ltd., consisting of a polymer powder having a weight-average molecular weight of approximately 5,000,000 and a structure represented by the formula (1) (volume-average particle size measured by the laser diffraction scattering method: approximately 40 μm)} <Water-soluble cationic thickener> HC Polymer 1S (M) {Osaka Organic Chemical Industry Co., Ltd.}: Vinylpyrrolidone-N,N-dimethylaminomethacrylic acid copolymer sulfate solution <Other thickeners> PEG: Polyethylene glycol (PEG) PMMA: Polymethyl methacrylate (PMMA) QS-102: Primary particle size is 12 nm, specific surface area measured by BET is 200 m 2 / g of fumed silica (manufactured by Tokuyama Corporation).

[0057] Example 1 An 85% by weight aqueous solution of phosphoric acid was mixed in a polypropylene container so that the total weight was 34.6 parts by weight of phosphoric acid, 65.4 parts by weight of distilled water, and 2.0 parts by weight of Coscut GA468, a water-insoluble powder cationic thickener, and the mixture was stirred for 5 minutes using a magnetic stirrer to obtain a dental etching agent.

[0058] The dental etching agent thus obtained was evaluated for shape retention, ejection property, and consistency. The shape retention and ejection property were evaluated by the following methods, and the consistency was determined by the method described above (see 1.(4)). The results of each evaluation are shown in Table 1.

[0059] <Method for evaluating shape retention and ejection properties of dental etching agents> 0.1 g of etching agent was applied to the surface of a bovine tooth and then placed vertically. After leaving it for 30 seconds, the displacement of the bottom end of the etching agent was measured to evaluate shape retention and ejection from the syringe. The evaluation was performed at 23°C. The bovine tooth was polished parallel to the tooth surface with P120 and P600 waterproof abrasive paper under water injection. A commercially available syringe (manufactured by Terumo Corporation) with a capacity of 2.5 cc and equipped with a nozzle tip (a syringe tip with a gauge size of 27 G conforming to ISO 09626; the inner diameter of the metal tube at the ejection site was 0.2 mm, the outer diameter of the metal tube at the ejection site was 0.4 mm, and the length of the metal tube at the ejection site was 11 mm) was used.

[0060] The evaluation criteria for each evaluation are shown below.

[0061] Shape retention evaluation criteria: ◎: Does not spread after application (less than 1 mm) ○: Slight expansion is acceptable (1mm to less than 2mm) ×: Too much spread (more than 2 mm).

[0062] Dischargeability evaluation criteria: ◎: Good controllability ○1: A little heavy but good ○2: A little light but good ×1: Too heavy ×2: Too light.

[0063] [Table 1]

[0064] Examples 2 to 7 and Comparative Examples 1 to 9 Dental etching agents were prepared and evaluated in the same manner as in Example 1, except that the types and amounts of the thickener and acid in Example 1 were changed as shown in Table 1. The results are shown in Table 1.

[0065] Examples 1 to 7 are examples of etching agents of the present invention that contain a water-insoluble powder cationic thickener as specified in the present invention, and as shown in Table 1, in all cases, shape retention and ejection properties were good.

[0066] In contrast, in Comparative Examples 1 to 5, in which an organic thickener other than a water-insoluble powder cationic thickener was used, the thickening effect was insufficient even when the blending amount was significantly increased, and good shape retention and ejection properties were not obtained. Furthermore, when an inorganic thickener was blended, as shown in Comparative Examples 6 and 7, increasing the blending amount improved shape retention, but caused clogging of the syringe tip, and good ejection properties were not obtained.

[0067] Furthermore, even when a water-insoluble powdery cationic thickener was used, the thickening effect was insufficient and good shape retention and ejection properties were not obtained in Comparative Example 8, where the blending amount was below the lower limit of the present invention. Conversely, when the blending amount exceeded the upper limit (Comparative Example 9), the ejection properties were too heavy.

Claims

1. A dental etching agent comprising a viscous fluid containing 100 parts by mass of an acid aqueous solution and 2.0 to 6.5 parts by mass of a powder that functions as a cationic thickener and is made of a water-insoluble polymer having an amino group.

2. The water-insoluble polymer is represented by the following formulas (A), (B), and (C) {wherein R １ represents a hydrogen atom or a methyl group, and R in formula (C) ２ represents a linear alkyl group having 1 to 17 carbon atoms.}, and the proportion of the structural unit represented by the following formula (A) in the entire water-insoluble polymer is 15 to 85 mass %. 【Chemical 1】

3. 3. The dental etching agent according to claim 1, wherein the water-insoluble polymer powder has a volume average particle size of 10 to 100 μm as measured by a laser diffraction scattering method.

4. The dental etching agent according to any one of claims 1 to 3, which is used for etching enamel.

5. A syringe-filled dental etching agent is provided in a state where the dental etching agent is filled in a syringe, and after a nozzle is attached, the dental etching agent is discharged from the nozzle and applied to a predetermined position of enamel, 5. The dental etching agent filled in a syringe, wherein the dental etching agent filled in the syringe is the dental etching agent according to claim 4.

6. 6. The syringe-filled dental etching agent according to claim 5, which is used with a nozzle having an inner diameter of a nozzle projection hole within a range of 0.07 to 0.8 mm.

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