JPH0667815B2 - Dental cement hardening liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a dental cement hardening liquid, and more specifically, it is an aqueous dispersion of a novel graft copolymer having particularly improved adhesiveness to the tooth structure. The present invention relates to a dental cement hardening liquid containing a liquid.

Compared with composite resins, glass ionomer cements used for dentistry have an extremely slight harmful effect on pulpal pulp, and exhibit adhesiveness to both enamel and dentin, and have a margin sealing property. It is useful for restoration of the anterior tooth portion as well as joint fitting of prostheses, temporary sealing, lining, and manufacturing.

<Prior Art> Dental cement hardening liquid has almost no pulp irritation,
Moreover, it is the only cement that has adhesive properties. Various studies have been made on the dental cement hardening liquid, for example, Japanese Patent Publication No. 54-21858, Japanese Patent Publication No. 55-8019 or Japanese Patent Publication No. 54-149296 discloses a desired treatment time and curing. Dental cement compositions containing chelating agents have been described to improve speed and fracture resistance.

However, in the above composition, the amount of the chelating agent added is 0.01 to 10% by weight, particularly preferably 5% by weight, that is, 10% by weight or less, based on the polycarboxylic acid.
For important adhesive properties as a dental cement hardening liquid,
The reality is that we are not fully satisfied.

Further, Japanese Patent Publication No. 50-26573 proposes a dental carboxylate cement hardening liquid, and although the operability and the crushing resistance are improved, the addition amount of an organic acid of 2 or more bases is a polycarboxylic acid. On the other hand, since it is 0.1 to 5.0% by weight, which is 10% by weight or less, there is a drawback that sufficient adhesiveness cannot be obtained as in the case of the above composition.

Further, in Japanese Patent Publication No. 61-4826, a composition comprising a trimellitic acid ester or its acid anhydride and at least one polymerizable compound having an ethylenically unsaturated bond is used for metals, teeth and the like. It has been proposed to have excellent adhesion.

However, in the above composition, 30% by weight of the tooth structure
Since an etching operation with a phosphoric acid aqueous solution is required, the operation is complicated, and furthermore, since the polymerizable compound is used as it is, it has a drawback that it stimulates dental pulp.

Furthermore, it is the fact that it is not known at all to make a dental cement hardening liquid contain a graft copolymer having a carboxylic acid group to obtain a hardening liquid for an aqueous dispersion.

<Problems to be Solved by the Invention> An object of the present invention is to provide excellent control of curing speed and crushing resistance,
Moreover, it is to provide a dental cement hardening liquid of an aqueous dispersion having excellent adhesiveness and disintegration rate.

<Means for Solving the Problems> According to the present invention, a graft copolymer containing a carboxylic acid group is contained in a curing liquid in an amount of 40 to 50% by weight, and a polybasic acid is added to 100 parts by weight of the graft copolymer. On the other hand, there is provided a dental cement hardening liquid of an aqueous dispersion characterized by containing 11 to 20 parts by weight.

The present invention will be described in more detail below.

The dental cement hardening liquid of the present invention is characterized by being an aqueous dispersion containing a graft copolymer containing a specific amount of a carboxylic acid group and a specific amount of a polybasic acid.

The graft copolymer used in the present invention is a copolymer which does not dissolve in water but is dispersible and has a carboxylic acid group. That is, preferably composed of a hydrophilic side chain containing a polymer of an unsaturated monomer having a carboxylic acid group and a hydrophobic main chain having no carboxylic acid group, or having a carboxylic acid group A hydrophilic main chain containing a polymer of an unsaturated monomer,
It is a cationically reactive graft copolymer composed of a side chain having no carboxylic acid group.

In the present invention, the polymerizable monomer for constituting the graft copolymer is an unsaturated monomer having the carboxylic acid group, specifically, (meth) acrylic acid, itaconic acid, maleic acid. , Glutaconic acid, aconitic acid,
Citraconic acid, mesaconic acid, fumaric acid, tiglic acid, crotonic acid, muconic acid, isocrotonic acid, 3-butenoic acid,
Preferable examples include cinnamic acid, abietic acid, maleic anhydride, itaconic anhydride, or substituted products or derivatives thereof, and an unsaturated monomer having no carboxylic acid group, specifically, for example, methyl ( (Meth) acrylate, ethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexyl (meth ) Acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate,
2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, glyceryl (meth) acrylate, dimethylamidoethyl (meth) acrylate,
Diethylaminoethyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 2,
3-dibromopropyl (meth) acrylate, trimethylolethane (meth) acrylate, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, vinyl acetate, styrene, α-methylstyrene, 2,2-bis [( (Meth) acryloyloxypolyethoxyphenyl]
Preferable examples include propane, 2,2'-bis [4- (3-methacryloyloxy-2-hydroxypropoxy) phenyl] propane, (meth) acrylonitrile, acrolein, or their substitution products or derivatives.

The blending ratio of the graft copolymer used in the present invention is in the range of 40 to 50% by weight, preferably 40 to 45% by weight in the curing liquid. When the blending ratio is less than 40% by weight, the crushing resistance is significantly reduced, and when it exceeds 50% by weight, the miscibility becomes extremely poor and it becomes difficult to mix it with the cement powder, so it is necessary to set it within the above range. is there. Also, the smaller the average molecular weight (polymerization average) of the graft copolymer, the lower the viscosity of the aqueous dispersion, which is suitable for kneading operability, but when it is less than 1000, the characteristics of the polymer in the glass ionomer are lost, and when it exceeds 500000, the aqueous dispersion is dispersed. The viscosity of the liquid increases and the kneading operability deteriorates.
The range of 00-500000 is preferable, and the range of 2000-200000 is particularly desirable. Moreover, the molecular weight of the side chain is preferably in the range of 500 to 300,000, and particularly preferably in the range of 1,000 to 100,000. Furthermore, in order to improve physical properties such as disintegration rate, adhesion to dentin, durability, and kneading operability, the unsaturated monomer containing a carboxylic acid group is 50 to 98% by weight in the graft copolymer. %, More preferably 70 to 95% by weight.

In the present invention, in order to prepare the graft copolymer, an unsaturated monomer having a carboxylic acid group is polymerized,
Obtaining the main chain of the graft copolymer, and then polymerizing an unsaturated monomer having no carboxylic acid group in the obtained main chain or by polymerizing an unsaturated monomer having no carboxylic acid group Then, the main chain of the graft copolymer is obtained, and in a sense, it can be obtained by a method of polymerizing an unsaturated monomer having a carboxylic acid group. The polymerization reaction when preparing the graft copolymer, for example, a redox reaction initiator such as a cerium salt,
Polymer containing a peroxide agent, polymer containing a diazo group,
A polymer containing a double bond, a polymer containing a mercapto group, a polymer containing an anion-generating group, or the like, or a method using a macromonomer or a condensation reaction between polymers can be synthesized. it can. Further, the polymerization reaction can be performed by known radical polymerization, ionic polymerization, photopolymerization or the like. The polymerization reaction may be performed by a known method and is not particularly limited. For example, in radical polymerization, the reaction temperature is 0 to 200 ° C and the reaction time is 1
It is preferably carried out in about 20 hours. If the temperature is lower than 0 ° C., the reaction rate is slow and a high molecular weight polymer may not be obtained, and if it exceeds 200 ° C., a side reaction occurs and a polymer having desired physical properties cannot be obtained, which is not preferable. Reaction time is 1
If it is less than the time, the polymerization reaction does not proceed sufficiently, the monomer remains, and the yield decreases, which is not preferable. When the polymerization reaction is carried out in an organic solvent, the molecular weight can be controlled relatively easily, so that a polymer having desired physical properties can be easily obtained.

Examples of the polybasic acid used in the present invention include tartaric acid, citric acid, malic acid, malonic acid, maleic acid, fumaric acid, phthalic acid, pimelic acid, nicotinic acid, oxalic acid, succinic acid, glutaric acid, glutamic acid, glutathioic acid. , Oxaloacetic acid, azelaic acid, aspartic acid, adipic acid, itaconic acid, aconitic acid, mesaconic acid, muconic acid, glutaconic acid, citraconic acid, trimellitic acid, pyromellitic acid, etc. Preferable examples thereof include organic acids or inorganic acids such as orthophosphoric acid, pyrophosphoric acid and tripolyphosphoric acid, which can be used alone or as a mixture.

In the present invention, the blending ratio of the polybasic acid is in the range of 11 to 20 parts by weight, preferably 15 to 20 parts by weight, based on 100 parts by weight of the polymer. When the blending ratio is less than 11 parts by weight, the improvement of the adhesiveness is not sufficient, and when it exceeds 20 parts by weight, the disintegration rate is lowered, and therefore the above range is required.

The dental cement hardening liquid of the present invention can be prepared by dispersing the graft copolymer containing a carboxylic acid group and the polybasic acid in water at a ratio within the above-mentioned specific range.

In the present invention, the method of using the dental senmet curing liquid,
For example, it is preferable to mix the dental cement hardening liquid of the present invention with a known cement powder in a weight ratio of 1: 1 to 3: 1. The cement powder is not particularly limited, for example, 25 to 35 wt% silicate, 10 to 20 wt% hydroxide, 2 to 15 wt% metal oxide, 25 to 35 wt% fluoride,
A mixture of 5 to 15% by weight of phosphate and 2 to 8% by weight of carbonate can be used, and a powder for zinc phosphate cement obtained by firing a mixed component consisting of zinc oxide and magnesium oxide. It is also possible to mix and use. The particle size of the cement powder is 100 microns or less, preferably 0.1 to 10 microns. The cement powder is not particularly limited as long as it can be kneaded at a filling consistency by changing the powder-liquid ratio, and a cement powder mixture having a high powder-liquid ratio can be used depending on the preferable surface characteristics of the cement powder.

<Effects of the Invention> Since the dental cement hardening liquid of the present invention contains a graft copolymer having a carboxylic acid group and a polybasic acid in a specific amount, it has particularly excellent adhesiveness and disintegration rate in the mouth. Can be added to cement for use.

<Example> Next, an example and a comparative example will be specifically described. The parts in the examples are parts by weight, and the molecular weight represents the weight average molecular weight by the GPC method (gel permeation chromatography).

Production Example 1 (Production of Graft Copolymer) In a polymerization method of methyl methacrylate, a macromonomer whose one end is methacrylate (number average molecular weight = 20)
00) 5 parts, acrylic acid 20 parts, itaconic acid 5 parts, ethyl alcohol 120 parts and 2,2'-azobisisobutyronitrile
0.1 part was charged into the reaction layer, the atmosphere was replaced with nitrogen for 30 minutes, and the mixture was refluxed at a temperature of 95 ° C for 8 hours. After completion of the reaction, the solvent was removed under reduced pressure, 300 parts of distilled water was added thereto, and freeze-dried. The polystyrene reduced molecular weight by GPC of the obtained graft copolymer was 56400.

Production Example 2 Production Example 1 except that a polymer of n-butyl methacrylate (number average molecular weight of 6000) was used in place of methyl methacrylate, the compounding amount of ethyl alcohol was 50 parts, and further 50 parts of isopropyl alcohol was added. Similarly, a graft copolymer was prepared. The polystyrene reduced molecular weight by GPC of the obtained graft polymer was 60300.

Production Example 3 (Production of Random Copolymer) A random copolymer was prepared in the same manner as in Production Example 1 except that 5 parts of methyl methacrylate was used instead of 5 parts of macromonomer in Production Example 1. GPC of the obtained polymer
The polystyrene-converted molecular weight according to the method was 46,000.

Examples 1 to 6 The graft copolymer obtained in Production Example 1 or Production Example 2,
The polybasic acid shown in Table 1 and distilled water were mixed at the mixing ratio shown in Table 1 to obtain a dental cement hardening liquid as an aqueous dispersion. Next, 1.0 part of the obtained hardening liquid and 1.8 parts of dental cement powder shown in Table 2 were kneaded for about 30 to 60 seconds, and the disintegration rate and the adhesive strength were measured according to the following measuring methods. The results are shown in Table 3. Table 1 shows the composition and amount ratio of the obtained effect liquid.

Measurement method 1. Disintegration rate Other than using 0.001M lactic acid aqueous solution instead of distilled water,
It carried out according to the disintegration rate test of JIS T6602.

2. Bonding strength A dental cobalt-chromium alloy rod is bonded to the dentin polished surface of the morning tooth with glass ionomer cement, and it is left for 37 hours.
After soaking in water at 0 ° C, the compressive shear bond strength was measured.

Comparative Examples 1 to 5 After preparing a dental cement hardening liquid using the polymer shown in Table 1, polybasic acid and distilled water, the dental cement powder shown in Table 2 was kneaded in the same manner as in Examples 1 to 6. Then, the disintegration rate and the adhesive strength were measured. The results are shown in Table 3.

Front Page Continuation (72) Inventor Yoshitaka Goto 2-24-5 Umezono, Tsukuba City, Ibaraki Prefecture (72) Inventor Masayo Nakayama 2-15-5 Umezono, Tsukuba City, Ibaraki Prefecture (56) Reference JP-A-52-3613 (JP, A) JP-A-52-101893 (JP, A)

Claims (1)

[Claims] 1. A graft copolymer containing a carboxylic acid group,
A dental cement hardening liquid for an aqueous dispersion, which is contained in an amount of 40 to 50% by weight in a hardening liquid and contains 11 to 20 parts by weight of a polybasic acid with respect to 100 parts by weight of the graft copolymer.