JPH05201824A - Hydraulic dental cement composition - Google Patents

Abstract

PURPOSE:To obtain a dental hydraulic cement composition having improved mechanical strength, adhesiveness and water resistance by blending polycarboxylate cement with a fibrous reinforcing material. CONSTITUTION:By taking advantage of aluminum borate whiskers having properties of a fibrous shape and crystal surface showing mutual action on a water-soluble carboxyl group, the maximum 50wt.% of the whiskers are blended with polycarboxylate cement to give a high-quality dental hydraulic cement composition having improved mechanical strength, adhesiveness and water resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dental hydraulic cement composition in which mechanical strength, adhesiveness and water resistance are improved by blending aluminum borate whiskers.

[0002]

2. Description of the Related Art Although zinc phosphate cement has been used as a dental cement for a long time, Smith et al. Of the University of Manchester developed polycarboxylate cement as a new dental cement and announced it in British Journal in 1968. did. Polycarboxylate cement is less irritating to pulp than zinc phosphate cement, and it has excellent adhesive strength with tooth structure and high tensile strength, so it is widely used today. There is. However, polycarboxylate cement
Compressive strength after hardening is 3 compared with zinc phosphate cement
There was a drawback that it decreased by about 50%.

Further, the addition of fibrous substances to plastics, metals, cements, ceramics and the like to improve the mechanical strength is a central technology of composite materials, and some of them are applied to dental materials. Has been announced. For example, JP-A-3-251513 and 3-504874.
Japanese Patent Application Laid-Open No. 59-227809 discloses addition of a fibrous substance to dental plastic, Japanese Patent Application Laid-Open No. 59-227809 describes addition of silicon nitride whiskers, Japanese Patent Application Laid-Open No. 63-44380 and Japanese Patent Application Laid-Open No. 3-16955. Have proposed whisker-reinforced calcium phosphate compounds.

However, polycarboxylate cement is composed of a powder part of oxides such as zinc oxide and magnesium oxide and a liquid part of polyacrylic acid aqueous solution,
Various studies have been conducted on the chemical components of the powder part or the liquid part in order to improve the compressive strength, but no report has been made on a reinforcing composition using whiskers or short fibers.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dental cement having excellent compressive strength, tensile strength, adhesive strength and water resistance after curing.

[0006]

Means for Solving the Problems As a result of many test studies in view of such circumstances, the present inventors have found that the crystal surface of aluminum borate interacts with the carboxyl groups of the polycarboxylate cement liquid part. By paying attention to the phenomenon described above, and further by adding aluminum borate whiskers to polycarboxylate cement, it was found that the intended purpose can be achieved, and the present invention has been completed.

The polycarboxylate cement used in the present invention is composed of two components, an inorganic powder called a powder part and a polyacrylic acid aqueous solution called a liquid part. It is used mainly for the gelation reaction of cations eluted from the powder part and the carboxyl group of polyacrylic acid to cure and to be used for restoration or attachment of prostheses and filling of tooth defects.

As the main component of the powder part, powders of zinc oxide, magnesium oxide, etc. are mainly used. In addition to these, recently developed silicon oxide, aluminum oxide, calcium fluoride, aluminum phosphate, cryolite. Etc. can be used.

The main component of the liquid portion is a polymer of acrylic acid or a copolymer of acrylic acid with an acrylic acid ester, a methacrylic acid ester or an unsaturated carboxylic acid (eg maleic acid, itaconic acid, aconitic acid, etc.). Is an aqueous solution of. In addition, low molecular weight carboxylic acids (eg citric acid, tartaric acid, maleic acid, etc.) in aqueous solutions of these polymers
Can be included.

As the aluminum borate whiskers to be blended with the hydraulic cement composition of the present invention, Japanese Patent Laid-Open Nos. 63-319298 and 63-319298 according to the invention of the present applicant.
Chemical formula 9Al ₂ O ₃ .2B described in Japanese Patent No. 319299.
Are those represented by ₂ O ₃ or 2Al ₂ O ₃ · B ₂ O _3, to fiber diameter of 0.1 to 5 [mu] m, the whiskers 100μm to fiber length is not 1 are suitable for use.

In carrying out the present invention, aluminum borate whiskers may be added when mixing commercially available products of polycarboxylate cement, and whiskers are uniformly mixed in advance with the powder portion of the commercially available polycarboxylate cement. After that, the liquid part may be mixed and used.

In carrying out the present invention, the mixing ratio of the powder part and the liquid part of the polycarboxylate cement is a predetermined amount which is commercially available. The mixing ratio of the aluminum borate whiskers and the polycarboxylate cement is
The amount of whiskers added should not exceed 50% by weight of the final mixture. When the weight ratio of the whiskers is more than the above range, the viscosity of the mixture becomes high, so that the whiskers cannot be sufficiently mixed and the wettability of the whiskers deteriorates.

[0013]

When the fibrous substance is added to plastics, metals, cements, ceramics, etc., the strength is improved because the fiber has a higher tensile strength than the matrix.
It is believed that the applied stress propagates through the adhesive force at the fiber-matrix interface.

The so-called whiskers refer to needle-shaped single crystals with a large aspect ratio, and their strength is high because there are few defects, so when added, conditions such as tensile strength can be sufficiently satisfied. is there. Therefore, such an effect can be expected using any chemical whisker, but when aluminum borate whiskers are added, the strength improvement rate is very large compared to other whiskers, and it becomes a simple fiber shape. It is unlikely that this is the only cause. It can be presumed that such a phenomenon is because the crystal surface of aluminum borate and the carboxylic acid portion, which is the liquid portion in the present invention, chemically interact with each other during curing, so that the adhesive force at the interface between the whiskers and the cement is improved.

Journal of the Ceramic Soc
According to "Interaction between alumina surface and polyacrylic acid" in Volume 100, January issue, pages 7-12, carboxyl groups interact with the surface of alumina particles in an aqueous solution. Has been done. The surface of alumina is A
Al-O-B-O has the same crystal structure as aluminum borate and has a crystal structure in which l-O is repeated.
It has the similarity that it is composed of a surface consisting of a structure that is repeated in. In addition, in the above paper, the author measured the zeta potential of alumina powder, and the isoelectric point
= 7.7, but this is the same value as aluminum borate.

Judging from the above-mentioned similarities, in the hydraulic dental cement composition of the present invention, the surface of the aluminum borate whiskers interacts with the carboxyl groups, which results in the adhesion between the whiskers and the cement matrix. Since it is improved, it is considered that the strength is expressed more than expected. Hereinafter, the present invention will be specifically described with reference to examples.

[0017]

Example 1 As the cement, a powder portion and a liquid portion of a commercially available dental polycarboxylate cement (trade name: Carlon SMFP, manufactured by Sankin Industry Co., Ltd.) were used. Average fiber diameter 1μm represented flour portion of the cement in the formula _{9Al 2 O 3 · 2B 2 O} 3, aluminum borate whiskers having an average fiber length of 20 [mu] m (trade name: Alborex G, manufactured by Shikoku Chemicals Corporation) and It was blended so that the final mixing ratio would be the ratio shown in Table 1, and mixed in a mortar to obtain a secondary powder part.

Next, the ratio of the secondary powder portion to the cement liquid portion was sampled at a weight ratio of 1.08: 0.60 and 3
After filling the Teflon mold with the mixture mixed for 0 seconds,
A cured product sample (diameter 6 mm x 12 mm) for compression test and a cured product sample (diameter 6 mm x 6 mm) for indirect tensile test were prepared by leaving at room temperature for 30 minutes. These samples were allowed to stand in water at 37 ° C. for 48 hours, after which the compressive strength and indirect tensile strength were measured. The results of these measurements are shown in Table 1, and the maximum compressive strength is 1. compared to the polycarboxylate cement containing no aluminum borate whiskers.
The indirect tensile strength was improved by 5 times and the indirect tensile strength was improved by about 3 times. The measurement tester used was Autograph AGS-500 manufactured by Shimadzu Corporation, and the crosshead speed was 2 mm / min.

[0019]

[Table 1]

[0020]

EXAMPLE 2 Using the same polycarboxylate cement as that used in Example 1, the average fiber diameter 0.5 The whiskers represented by the chemical formula _{2Al 2 O 3 · B 2 O} 3
Using aluminum borate whiskers (trade name: Arbolex G, manufactured by Shikoku Kasei Kogyo Co., Ltd.) having an average fiber length of 20 μm, the whiskers were mixed so that the final mixing ratio was 50%, and mixed in a mortar. The secondary powder part was used. Further, the ratio of the secondary powder portion and the cement liquid portion is 1.08: 1.0.
A sample of the cured product was prepared in the same manner as in Example 1 by collecting at a weight ratio of 0. Using this sample, the compression strength and indirect tensile strength were measured by the same method as in Example 1,
The measurement results as shown in Table 1 were obtained, and the same reinforcing effect as in Example 1 could be confirmed.

[0021]

EXAMPLE 3 Using the same materials as in Example 1, the same method by 9Al ₂ O ₃ · 2B final mixing ratio of the aluminum borate whiskers represented by ₂ O ₃ is 0 or 20 wt%
A polycarboxylate cement composition was prepared so as to have the following composition, and the tensile adhesive strength was measured. Dental gold-silver-palladium alloy is used as the adherend, and the adhesive surface is 1
It was ground with No. 000 water-resistant emery paper, and a cellophane adhesive tape with a hole having a diameter of 5 mm was attached to this to define the adhesion area. The polycarboxylate cement composition was placed on the hole and the surface to be adhered of the nut-like metal and lightly pressed with a finger for adhesion. Then, these were left at room temperature for 30 minutes to harden the cement, and further left in water having a water temperature of 37 ° C. for 48 hours, and then the tensile adhesive strength was measured under the condition of a crosshead speed of 1 mm / min. These measurement results showed that the tensile adhesive strength was 3.1 MPa when the aluminum borate whiskers were not added, but the tensile adhesive strength was 4.5 when 20% by weight of the whiskers were added.
It was MPa.

[0022]

[Example 4] Using the cured product sample for compressive strength measurement, which was compounded and cured so that the final mixing ratio of the aluminum borate whiskers obtained in Example 1 was 0 or 10% by weight, water resistance was used. The test was conducted. Water temperature of these samples 37
After standing in water at 30 ° C. for 30 days, the compressive strength was measured by the same method as in Example 1. When the aluminum borate whiskers were not added, the compressive strength slightly decreased from 64 MPa to 63 MPa. When using a sample containing 10% whiskers,
It increased from 73 MPa to 78 MPa, and it was found that its water resistance was good.

[0023]

[Example 5] As a dental polycarboxylate cement in place of the Carlon SMFP used in Example 1, a trade name A: GSI GF ionomer type I (manufactured by GC Dental Industry Co., Ltd.) and a trade name B: HYBOND (Shofu) (Manufactured by Co., Ltd.) and mixed by the same method as in Example 1 such that the final mixing ratio of aluminum borate whiskers was 20% by weight to prepare a cured product sample. .. When the compressive strength and the indirect tensile strength were measured using these samples, the measurement results are shown in Table 2.
It was confirmed that the same strength development as in Example 1 was confirmed.

[0024]

[Table 2]

[0025]

EFFECT OF THE INVENTION A hydraulic dental cement composition in which aluminum borate whiskers are blended with polycarboxylate cement has significantly improved mechanical strength, adhesive strength and water resistance as compared with conventional polycarboxylate cement. It is useful as a highly reliable dental bonding material and filling material, and has high utility value in dental applications.

Claims (2)

[Claims] 1. A hydraulic dental cement composition comprising a polycarboxylate cement and aluminum borate whiskers. 2. A chemical formula _{9Al 2 O 3 · 2B 2 O} 3 or _{2Al 2 O 3 · B 2 O} 3 hydraulic dental cement composition according to claim 1 using aluminum borate whiskers represented by.