JP2813906B2 - Dental cement hardener - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a cement hardened material which is excellent in operability and kneadability when mixed with cement powder, and which is excellent in physical strength such as crush resistance. It relates to the resulting dental cement hardener.

<Prior art and problems to be solved> Dental cement is widely used as a restoration material for teeth, a bonding material for inlays or crowns, a bonding material for orthodontic teeth, a backing material, and the like.

Examples of these dental cements include zinc phosphate cement, polycarboxylate cement containing zinc oxide as a main component, calcium phosphate cement containing calcium phosphate as a main component, fluoroaluminosilicate glass and alkali earth metal aluminofluorosilicate glass. Glass ionomer cements and the like are known as typical cements.

Immediately before use, these cements are mixed and kneaded with an aqueous solution of a cement hardener immediately before use, and the kneaded material is filled in an affected area to form a hardened cement. As the aqueous cement hardener solution, an aqueous solution of a linear acrylic acid polymer or a copolymer of acrylic acid and another copolymerizable unsaturated monomer is most widely used. When this hardener aqueous solution is used for the various cements, the respective advantages,
Although the problem has already been clarified, a common major problem is that the kneadability with the cement powder is not sufficient.

Usually, the cement powder and the hardener aqueous solution are mixed and kneaded at a fixed ratio on a kneading plate (or kneading paper), and before the hardening reaction substantially proceeds, that is, in a state of high fluidity, In addition, it must be applied to the affected area, so that the kneading operation has to be completed in as short a time as possible. In addition, if the kneading is not performed sufficiently in a short time, the original performance of the cement is not exhibited, and as a result, the final performance of the hardened cement material tends to vary.

However, it is difficult to mix a cement powder, which is originally hardly compatible with water, with a hardener aqueous solution in a short period of time, and it is difficult to knead the mixture with a spatula or the like. Was. In view of such circumstances, the present inventors have conducted intensive studies and as a result, have found a hardening agent which is excellent in kneadability with cement powder and the like, and which can obtain a hardened cement material having excellent physical strength, and reached the present invention. It was done.

<Means for Solving the Problems> That is, the present invention relates to a method for preparing an unsaturated carboxylic acid monomer or a mixed monomer of the monomer and another copolymerizable unsaturated monomer in an aqueous medium in the presence of a dental cement powder. The present invention relates to a dental cement hardener comprising a polymer-cement composite obtained by polymerization.

 Hereinafter, the present invention will be described in detail.

As the dental cement powder used in the present invention, various known cements usually used for dental cement can be used without any particular limitation. Specifically, for example, fluoroaluminosilicate glass made of silica, alumina, cryolite, fluorite or the like, or alkali aluminofluorosilicate made of silica, alumina, cryolite, aluminum fluoride, aluminum phosphate, strontium fluoride or the like Representative examples include glass ionomer cement powder represented by earth metal salt glass, polycarboxylate cement powder containing zinc oxide as a main component, calcium phosphate cement powder such as α-calcium triphosphate, calcium tetraphosphate, calcium octaphosphate, and the like. It is mentioned as a typical thing.

The particle size of the cement powder is 50 μm or less from the viewpoint of dispersion stability of the obtained polymer-cement composite aqueous suspension,
Preferably, 1 to 10 μm is appropriate.

As the unsaturated carboxylic acid monomer which is a constituent monomer of the polymer used in the present invention, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, aconitic acid, glutaconic acid, sicolaconic acid, mesaconic acid, One type such as tiguric acid or a mixture of two or more types thereof is mentioned as a typical example.

Other copolymerizable unsaturated monomers include one or more of acrylonitrile, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl propionate, methyl itaconate, styrene, 2-hydroxyethyl methacrylate, and the like. Mixtures are mentioned as representative.

The average molecular weight of the obtained polymer is preferably 1,
About 500 to 150,000 is appropriate, and the constituent ratio of the unsaturated carboxylic acid monomer in the polymer is preferably 90 to 100.
The weight percentage is appropriate, but not limited thereto.

A typical aqueous medium used in the present invention is water or a medium containing water as a main component and a mixture of water-soluble alcohols such as ethanol, isopropanol, hydrophilic glycol, polyhydric alcohol and lower alkyl ether thereof. It is listed as.

Next, a typical method for producing the dental cement hardener of the present invention will be described, but it is needless to say that the method is not limited to this method.

An aqueous medium containing a known polymerization initiator such as a persulfate, hydrogen peroxide, an organic peroxide or a redox system, and a chain transfer agent for adjusting the molecular weight if necessary, and in which cement powder is dispersed. An unsaturated carboxylic acid monomer or another monomer copolymerizable with the unsaturated carboxylic acid monomer is dropped therein to cause radical polymerization. The polymerization conditions are not particularly limited, but generally it is appropriate to carry out the polymerization at 50 to 100 ° C. under normal pressure. The ratio of the cement powder and the monomer is not particularly limited except for physical and chemical conditions that substantially hinder polymerization, but the stability of the resulting polymer-cement composite aqueous suspension is not limited. Considering the original function as a curing agent, the weight ratio (0.1 to 1
0): (99.9 to 90) is appropriate. Preferably, for example, when the cement powder is a glass ionomer cement, the weight ratio is (0.1-5) :( 99.9-95): α-
In the case of calcium triphosphate powder, weight ratio (0.1 to 10):
(99.9-90) is particularly preferred. Since the reactivity differs depending on the type of the cement powder, a suitable ratio can be appropriately selected.

The cement hardener of the present invention thus obtained is
An aqueous suspension of the polymer-cement composite obtained by polymerization in the aqueous medium can be used as a curing agent, or a suspension obtained by adjusting the concentration of the suspension in an aqueous medium can be used as a curing agent. It is also possible to temporarily turn the suspension into a polymer-cement composite powder by means such as freeze-drying, and to disperse and suspend the suspension again in an aqueous medium before use. However, it is desirable to remove and purify unreacted residual monomers and the like. For example, a dry powder of a polymer-cement composite is once produced by a freeze-drying method as a means, and this is re-suspended and dispersed in pure water to ensure safety. It is preferable to use a highly hardened and stable cement hardener. The solid content concentration of the cement hardener is arbitrarily determined according to the type and particle size of the cement powder component, but generally, 30 to 70% by weight is appropriate.

As described above, the reason why the aqueous suspension of the curing agent composed of the polymer-cement composite of the present invention as described above has improved kneadability with the cement powder component is not clear, but is presumed to be due to the following reason. Is done.

Constituting a complex as a hardener, the cement powder surface is ionic, and when it comes into contact with an unsaturated carboxylic acid monomer having a carboxyl group having chelate binding or ionic binding ability, the cement powder surface is blended in, When the monomer is polymerized while keeping it wet, the secondary agglomerates consisting of aggregates of the primary particles of the cement are loosened apart, and finally polymer chains with good affinity for aqueous media are formed. It is considered that fine particles of the polymer-cement composite wrapped with the polymer having the fine particles are obtained, and a good dispersion system is completed.

The fact that the cement particles are finely divided and dispersed with the formation of the polymer is easily understood from the fact that it has been confirmed that the polymerization catalyst is crushed and powdered as the polymerization reaction proceeds in catalytic chemistry. Presumed.

When the dried cement powder component is brought into contact with the aqueous suspension of the hardener comprising the polymer-cement composite of the present invention thus obtained, the cement powder component is easily incorporated into the aqueous suspension system. As soon as wetting, mutual familiarity is improved, and dispersion stability is improved, as a result, fluidity is improved, resistance during kneading is reduced, and operability and kneadability are improved. Conceivable.

This phenomenon is well understood from the fact that once a stable system is formed in a certain colloid or emulsion system, it becomes easier to take in a new medium, and the process of rapidly shifting to dispersion stabilization has been confirmed. It matches. Such effects are also supported by some data.

For example, to dry cement powder having the same particle size distribution,
A curing agent having the same concentration, that is, a conventional aqueous solution of a polyacrylic acid polymer, and an aqueous suspension of the polymer-cement composite of the present invention were respectively mixed, and the same amount of the kneaded material in the initial stage of kneading was mixed on a glass plate. When the aqueous suspension of the polymer-cement composite as the curing agent of the present invention was used, the film thickness was slightly widened. This also proves that the cement powder is loosened well in a short period of kneading and is in a uniformly dispersed state.

The aqueous suspension (L) of the curing agent comprising the polymer-cement composite of the present invention is used immediately before use as the cement powder component (P).
In general, (P) / (L) (weight ratio) is mixed and kneaded at a ratio of 1 to 3 and used for use.
For example, ethylenediaminetetraacetic acid, dihydroxytartaric acid, salicylic acid, 2,4- and 2,6-dihydroxybenzoic acid, citric acid, nitrilotriacetic acid, tartaric acid to improve initial curing speed, hardness, adhesion, crushing resistance, disintegration rate, etc. It is preferable to add a chelating agent such as a compound having two or more carboxyl groups in the molecule, β-diketone, polyglycol, etc. to the whole by several weight%.

<Effect of the Invention> The dental cement hardener comprising the polymer-cement composite of the present invention is superior to conventional hardeners when mixing with a dry cement powder component, and has excellent operability and kneadability, Therefore, it can be sufficiently kneaded in a short time without requiring much skill.
In addition, it has the effect of obtaining a hardened cement material having excellent physical strength such as crushing resistance and the like, and having no variation in final performance.

Hereinafter, the present invention will be described in more detail with reference to Examples.
In the examples, "parts" and "%" are shown on a weight basis.

<Preparation method of α-TCP powder> According to a known method, an equimolar mixture of γ-calcium pyrophosphate and calcium carbonate is uniformly mixed, and then calcined to synthesize α-tricalcium phosphate. The mixture was passed through a mesh sieve to obtain α-tricalcium phosphate powder.

<Method of preparing glass ionomer cement powder> Al ₂ O ₃ 100 parts, SiO ₂ 175 parts, Na ₃ AlF ₆ 30 parts, CaF ₂
207 parts, AlF ₃ 32 parts, AlPO ₄ 60 parts were pulverized and mixed, 1150
C., and then crushed and passed through a 400 mesh sieve to obtain a glass ionomer cement powder.

Example 1 64.00 parts of water, 8.00 parts of ethanol, 4.00 parts of itaconic acid,
A synthesis reactor equipped with a flask containing 0.10 parts of the glass ionomer cement powder was maintained at 80 ° C., and 0.70 parts of ammonium persulfate (APS) was added as a polymerization initiator to 4.00 parts of water.
Then, 16.00 parts of acrylic acid was uniformly dropped by a dropping funnel over 2 hours. After completion of the dropwise addition, a mixture of 0.30 parts of APS and 4.00 parts of water was added as an additional catalyst, and aging was further performed at 80 ° C. for 90 minutes. next,
In order to remove unreacted monomer, this was freeze-vacuum-dried, and 49.50 parts of the obtained powder and 45.0 parts of water were mixed to produce a curing agent aqueous solution.

Example 2 A curing agent aqueous solution was produced in the same manner as in Example 1 except that the amount of the glass ionomer cement powder was changed to 1.00 part.

Example 3 A hardener aqueous solution was produced in the same manner as in Example 1 except that the amount of the glass ionomer cement powder was changed to 2.00 parts.

Example 4 In Example 1, 4.00 parts of itaconic acid was replaced with aconitic acid
A curing agent aqueous solution was produced in the same manner as in Example 1 except that 4.00 parts was used.

Example 5 In Example 1, the glass ionomer cement powder was used.
0.10 parts of the α-tricalcium phosphate (α-TCP) powder 0.1
A curing agent aqueous solution was produced in the same manner as in Example 1 except that 0 part was used.

Example 6 A curing agent aqueous solution was produced in the same manner as in Example 5, except that 0.10 part of the α-TCP powder was changed to 1.00 part.

Example 7 A curing agent aqueous solution was produced in the same manner as in Example 5, except that 0.10 part of the α-TCP powder was changed to 5.00 parts.

Example 8 A curing agent aqueous solution was produced in the same manner as in Example 5 except that 0.10 part of the α-TCP powder was changed to 10.00 parts.

Comparative Example 1 A hardener aqueous solution was produced in the same manner as in Example 1 except that the glass ionomer cement powder was not added.

9.5 parts of the aqueous curing agent solution thus obtained and tartaric acid
0.5 part of the liquid agent and 18.0 parts of the glass ionomer cement powder were kneaded for 30 seconds, and the crush resistance 24 hours later was measured according to the method described in JIS T 6602 for dental cement. The kneadability test was determined as follows.

Kneadability test: 0.30 part of the powder and 0.20 part of the liquid were placed on kneaded paper, kneaded for 15 seconds, the kneaded cement composition was placed on a glass plate, and a glass plate weighing 20 g was placed on the glass plate. A weight of 100 g was placed on the top, and the average value of the maximum diameter and the minimum diameter of the sample that spread after 10 minutes was determined, and this was used as a measure of kneadability (fluidity). The larger the average value, the better the kneadability.

 The results are shown in Table 1 below.

As is clear from Table 1, the dental cement of each example using the hardener of the present invention had improved crushing resistance and kneading property as compared with Comparative Example 1 using the conventional hardener.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) A61K 6/00

Claims (2)

(57) [Claims] 1. A polymer-cement composite obtained by polymerizing an unsaturated carboxylic acid monomer or a mixed monomer of said monomer and another copolymerizable unsaturated monomer in an aqueous medium in the presence of dental cement powder. Dental cement hardener consisting of body. 2. The hardening agent for dental cement according to claim 1, wherein said cement powder is a glass ionomer cement powder.