JPS61191606A - Calcium phosphate composition for dental use - Google Patents

Abstract

PURPOSE:To obtain the titled composition having excellent biocompatibility, and integrable with the dental tissue, by calcining a mixture of dibasic calcium phosphate and calcium carbonate at a specific molar ratio, and adding barium sulfate, calcium hydroxyapatite and a kneading liquid to the calcined product. CONSTITUTION:Dibasic calcium phosphate of formula CaHPO4 or its dihydrate of formula CaHPO4-2H2O is mixed with calcium carbonate at a molar ratio of 2:1, and the mixture is calcined and pulverized to fine powder. The objective fluid or plastic composition for filling a dental cavity can be produced by mixing the above powder with a kneading liquid composed of barium sulfate, calcium hydroxyapatite, and water, physiological saline water, aqueous solution of polyacrylic acid, aqueous solution of acrylic acid-itaconic acid copolymer, or their mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dental cement that has excellent biocompatibility and is later integrated with tooth tissue.

Dental cement has been used for about 100 years and is an essential material for dental treatment, with a wide range of uses including bonding, filling, lining, pulp protection, and temporary sealing. There are many types of cement, including zinc phosphate cement, which is made by mixing zinc oxide with an aqueous solution of orthophosphoric acid;
Silicate cement made by kneading silicon oxide with phosphoric acid aqueous solution,
The main types are carboxylic acid cement, which is made by kneading zinc oxide with a polyacrylic acid aqueous solution, and ionomer cement, which is made by kneading silicon oxide with a polyacrylic acid aqueous solution. In addition, polycarboxylic acid aqueous solution is freeze-dried and powdered.
There is also a hydraulic carboxylate cement that is mixed with zinc oxide in advance and mixed with water before use.

The main components of dental cement powder made by these known techniques are zinc oxide, silicon oxide, and aluminum oxide,
Calcium fluoride, magnesium oxide, pickling methods, etc. are added as trace ingredients.

In addition, as described in JP-A No. 58-83605 as a recent known technique, a freeze-dried powder of a polymer of unsaturated carboxylic acid such as polyacrylic acid and zinc oxide is mixed in advance into hydraulic carboxylic acid cement. , hydroxyapatite (CaH(PO4)6(OH)2).

Apatite has low chemical +i activity, and metal oxides such as zinc oxide react with unsaturated carboxylic acids, which are cement binders. Therefore, as the amount of apatite mixed in increases, the physical properties (fracture resistance, collapse rate) decrease. Therefore, the biocompatibility of apatite and the physical properties of zinc oxide are in an antinomic relationship, and apatite 1
Biocompatibility is not considered to be sufficient unless it is reduced to 00%.

In any case, dental cements according to the prior art use metal oxides such as zinc oxide as a main component, and therefore have many problems in terms of biocompatibility. In particular, for dental cement that is often used in areas close to the bone marrow, it is necessary to use materials with excellent biocompatibility.

As previously described in detail in Japanese Patent Application No. 59-056676, the present inventor focused on the biocompatibility, progeny and self-hardening properties of α-tricalcium phosphate, and proposed a human hard tissue substitute material. The present invention describes the details of a dental cement composition, which is a specific application thereof.

The dental cement powder according to the present invention contains α-tricalcium phosphate as a main component, and if necessary, a calcium phosphate compound having excellent biocompatibility such as calcium may be mixed with hydroxyapatite and phosphoric acid. When X-ray contrast properties are required, such as as a lining agent for tooth cavities used for pre-filling with composite resin, etc., an appropriate amount of barium sulfate, etc. may be added.
Preferably within 100 ft. Furthermore, when used as a root canal filling material, etc., it may be necessary to distinguish it from tooth dentin, and a pigment (food additive) may be added to give it a different hue from dentin. As an auxiliary agent to adjust the curing time after kneading,
Carboxylic acid compounds such as citric acid, tartaric acid, malic acid, glycolic acid, and lactic acid may be added as necessary.

As the kneading liquid, as known in the art, water, physiological saline, aqueous solutions of inorganic salts, aqueous solutions of carboxylic acids (organic or inorganic),
An aqueous solution of a single polymer or a copolymer of two or more unsaturated carboxylic acids can be considered. Preferable results have been obtained when the concentration of the aqueous solution of the unsaturated carboxylic acid polymer is 20 to 60%. Alternatively, a method may be considered in which the above-mentioned acids are mixed in advance into powder in a dry state, and only water is added at the time of use (kneading).

The present invention will be explained in more detail below using experimental examples and examples.

Experimental Example 1 (Powder I) CaHPO4.2H20 or 2 moles of CaHPO4 and 1 mole of CaC0a are thoroughly mixed, dried at 100°C for about 1 hour, and then calcined at 1200°C for 2 hours. After firing, it is ground into a fine powder that passes 350 mesh. In order to obtain a powder with a higher density, the powder is compressed by a rubber press method and then re-fired at 1250° C. to become a fine powder.

(Powder ■) Powder 110y calcined by the above method is mixed in 1,000 liters of water, reacted at 80° C. for 4 hours, and the reactant is taken from house to house and dried to obtain hydroxyapatite.

(Kneading solution) When kneaded with a 20 to 60 weight aqueous solution of an acrylic acid polymer or an aqueous solution of a copolymer of unsaturated carboxylic acids, which is known in the art, it hardens in 3 to 20 minutes. The average molecular weight of the polymer and the concentration of the water bath solution must be adjusted depending on the application. In addition, physiological saline was adjusted to pH 6.5 to 4 with a small amount of nitric acid.
Even if it is kneaded with a solution adjusted to 5, it will harden in 8 to 40 minutes.

Example CaHPO4.2H20 or CaHPO4 and CaC
Table I shows an example of a composition using Powder I obtained by mixing and firing Powder 03, Powder 1 which is apatite obtained by hydration reaction of Powder 1, and Ba So 4 which is an X-ray contrast agent.

(Powder) Table - ■ (% by weight) Powder ■ Powder II Ba5O dye a 87.
65 0 12.05 0.03b 86.
17 13.80 0 0.03c 20
．． 85 70.25 8.87 0.03d
38.35 51.35 10.28 0.02
(Liquid) As an aqueous solution of a polymer or copolymer of unsaturated carboxylic acids such as acrylic acid, a copolymer of 85 mol of acrylic acid and 15 mol of itaconic acid was selected and polymerized using a known technique. .

l! : 50% aqueous solution of a copolymer of 85% acrylic acid and 15% itaconic acid (m): 20% aqueous solution of the same copolymer Example 2 (1) Powder a and liquid L were kneaded at a powder-liquid ratio of 1.5. A composite resin was applied to the artificially created cavity floor of the mandibular premolar tooth, and then filled with composite resin. After 8 weeks, the tooth was extracted, specimend, and observed. As a result of the composite resin not reacting, the tooth had not invaded the pulp, and calcification had progressed from the contact surface with the tooth.

(2) Powder d and solvent m were mixed at a powder-liquid ratio of 1.5, and the apical foramen of the mandibular root canal was enlarged with a reamer, and the mixture was filled. A hard tissue matrix with a width of about 8 pm was formed after one week in contact with one of the apical fillings. In the cases in which the filling was applied after 8 weeks, calcification had progressed, and in a few cases, the enlarged apical foramen was completely closed with calcified material.

Claims (2)

[Claims] (1) Barium sulfate [BaSO_4], calcium hydroxyapatite [Ca_1_0 (PO_4) )_6(
A fluid or plastic tooth filling composition characterized by comprising: OH)_2] and a kneading liquid. (2) A patent claim characterized in that the kneading liquid is selected from the group consisting of water, physiological saline, an aqueous polyacrylic acid solution, an aqueous solution of an acrylic acid-itaconic acid copolymer, or a mixture thereof. The composition according to item 1.