JPH0523385A - Calcium phosphate cement - Google Patents

Abstract

PURPOSE:To enhance strength and acid resistance, to reduce the irregularity of strength and to shorten a curing time by using a powder based on calcium phosphate cement composed of a specific composition rich in biocompatibility and a liquid containing specific fluoride as base materials. CONSTITUTION:Water containing fluoride selected from the group consisting of NaF, KF, NH4 and a mixture of them is mixed with a cement powder prepared by mixing alpha-type calcium tertiary phosphate and calcium secondary phosphate so that a Ca/P mol ratio becomes 1.40-1.498 and the resulting mixture is cured. By this method, acid resistance is enhanced and a curing time can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a calcium phosphate cement which can be used as an orthopedic cement such as a filling material for bone defects and bone voids, or a dental cement such as a backing layer and a pulp capping material.

[0002]

BACKGROUND OF THE INVENTION Hydraulic calcium phosphate is useful as a tooth and bone restorative material because it is converted into a compound similar to the main components of teeth and bones in the body by setting and hardening.
Further, it is known to be useful as an adsorbent for biopolymers and harmful organic substances or inorganic ions in the living body.

Conventionally, as the hydraulic calcium phosphate, calcium phosphate cement, which uses a combination of salts and a dilute acid as a hardening liquid in JP-A-59-88351, is not disclosed in JP-A-60-253454. A calcium phosphate cement using an acidic solution containing a saturated carboxylic acid polymer is disclosed.
However, in the hydraulic calcium phosphate, until the hardening of the cement is completed, there is a problem that the acidity of the hardening liquid is strong and gives considerable irritation to the living body.
Further, there is a problem that the pH is lowered due to the elution of unreacted acid even after the hardening of the cement, resulting in irritation to the living body.

Therefore, in order to solve such a problem, hydraulic calcium phosphate cement which is hardened by water has been developed (for example, FC REPORT, vol. 6 (19).
88), p. 475-480 "Hydraulic apatite as bioceramics"). The hydraulic calcium phosphate that is hardened by water is described in JP-A-64-37445.
In the publication, simply kneading with water at 37 ° C,
A hydraulic calcium phosphate cement that hardens in about 10 minutes has been proposed. The hydraulic calcium phosphate has a pH
It is almost neutral and causes less irritation to the living body, and solves the problems of conventional hydraulic calcium phosphate cement.

However, the above-mentioned hydraulic calcium phosphate has a problem that the curing time is rather long in practical use and the acid resistance of the cured product itself is low, so that the risk of deterioration and destruction particularly when used for dentistry is extremely high. is there.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a calcium phosphate cement having excellent biocompatibility, short curing time, practically sufficient strength, and excellent acid resistance. ..

[0007]

According to the present invention, Ca / α-type tribasic calcium phosphate and dibasic calcium phosphate
A powder agent containing a mixture having a P molar ratio of 1.40 to 1.498 as a main component and a liquid agent, wherein the liquid agent is NaF or K.
There is provided a calcium phosphate cement characterized in that it contains a fluoride selected from the group consisting of F, NH ₄ F and mixtures thereof.

The present invention will be described in more detail below.

In the calcium phosphate cement of the present invention, the α-type tribasic calcium phosphate and the dibasic calcium phosphate used as the main components of the powder are components which react in the presence of water to produce 8-calcium phosphate and harden. .. The 8-calcium phosphate is a component that is rapidly converted into hydroxyapatite in vivo. As the dicalcium phosphate, commercially available dicalcium phosphate 2
A hydrate and the like can be preferably mentioned. The reaction proceeds most rapidly at pH 6-8.

The mixing ratio of the α-type tribasic calcium phosphate and the dibasic calcium phosphate is 1.4 in terms of Ca / P molar ratio.
It must be in the range of 0 to 1.498. Ca / P
When the molar ratio is less than 1.40, the maximum strength is poor, and 1.
If it exceeds 498, the initial strength tends to be poor, so it is necessary to set it in the above range. At this time, the Ca / P molar ratio is 1.40.
In the case of 1.47, the initial strength is excellent and 1.47 to 1.4
In the case of 98, the maximum strength that develops on the 3rd day after curing is excellent.

In the calcium phosphate cement of the present invention, a liquid agent for hardening the powder is prepared by shortening the hardening time of the cement and replacing the hydroxide ion in the hydroxyapatite produced by hardening the cement with a fluorine ion. NaF, K to improve acid resistance
It is necessary to include a fluoride selected from the group consisting of F, NH ₄ F and mixtures thereof.

[0012] The mixing ratio of the above-mentioned fluoride is preferably such that the concentration in the liquid preparation is in the range of 0.001 mol / l to 1 mol / l. If it is less than 0.001 mol / l, the effect of shortening the curing time cannot be obtained, and if it exceeds 1 mol / l, fluorine affects the living body, which is not preferable.

In the present invention, water is sufficient as the base material of the liquid agent containing the fluoride, but in order to improve the operability, mucopolysaccharides such as sodium chondroitin sulfate and sodium hyaluronate, Water-soluble sodium salts such as sodium succinate and sodium lactate may be added to shorten the curing time.

The mixing ratio of the powder agent and the liquid agent is preferably in the range of 1.0 to 3.0: 1 by weight. If the mixing ratio of the powder is less than 1.0, it takes a long time to cure, and if it exceeds 3.0, the operability during kneading is deteriorated, which is not preferable.

Further, the calcium phosphate cement of the present invention may contain barium sulfate, bismuth subcarbonate, yo-yo, if necessary.
X-ray contrast agents such as doform; antibacterial agents such as iodoform and chlorhexidine may be added and used.

[0016]

The calcium phosphate cement of the present invention is
Since the base material is a powder agent containing calcium phosphate cement of a specific composition rich in biocompatibility as a main component, and a liquid agent containing a specific fluoride, it has excellent biocompatibility, high strength and little variation in strength, and Short curing time and excellent acid resistance. Further, when used as a dental cement, it has a caries preventive effect due to gradually released dissolved fluoride ions.

[0017]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0018]

Reference Example 1 α-type tribasic calcium phosphate and dibasic calcium phosphate (manufactured by Wako Pure Chemical Industries, Ltd .; dibasic calcium phosphate dihydrate, special grade) at a Ca / P molar ratio of 1.40,
Cement dusts were obtained by mixing them so as to be 1.45, 1.48 and 1.498, respectively. Then the obtained powder 10
0 parts by weight and 60 parts by weight of water as a liquid agent were kneaded and cured. Further, the curing time and the compressive strength of the obtained cement cured product were measured. The results are shown in Table 1. Curing time is JI
According to SR5201, the compressive strength was measured by immersing the cement hardened body (7 mmφ, 14 mmL) in the artificial body fluid for 3 days, and then taking it out and using a universal testing machine manufactured by Instron.

[0019]

Reference Example 2 The curing time and compressive strength were measured in the same manner as in Reference Example 1 except that the Ca / P molar ratios of α-type tribasic calcium phosphate and dibasic calcium phosphate were changed to 1.33 and 1.499. The results are shown in Table 1.

[0020]

[Table 1]

[0021]

Examples 1 to 3 100 parts by weight of cement dust prepared by mixing α-type tribasic calcium phosphate and dibasic calcium phosphate so that the Ca / P molar ratio was 1.48, at the concentration shown in Table 2 as a liquid agent, 60 parts by weight of water containing fluoride shown in Table 2 was mixed and cured, and the curing time and compressive strength were measured. The results are shown in Table 2.

[0022]

[Table 2]

[0023]

Example 4 100 parts by weight of cement dust prepared by mixing α-type tricalcium phosphate and dicalcium phosphate in a Ca / P molar ratio of 1.45 was added to water containing NH ₄ F (0.25 mol). / L) 60 parts by weight were mixed as a liquid agent and cured. Five molded bodies (20 mmφ, 10 mmL) obtained by molding the obtained cured body into a constant shape were always used.
After immersing in an aqueous citric acid solution adjusted to pH 3 at 30 ° C for 30 days, it was taken out and the diameter was precisely measured using a micrometer to calculate an average value of 19.85 ± 0.
It was 03 mm.

[0024]

[Comparative Example 1] A cured product was prepared in the same manner as in Example 4, except that water containing no fluoride was used as the liquid agent, and after dipping it in an aqueous citric acid solution, the diameter was measured.
It was ± 0.07 mm.

From the results of Example 4 and Comparative Example 1, it can be seen that the calcium phosphate cement of the present invention has excellent acid resistance.

Claims (1)

Claims: 1. A Ca / P molar ratio of α-type tribasic calcium phosphate and dibasic calcium phosphate is 1.40 to 1.498.
Consisting of a powder having a mixture as a main component and a liquid,
A calcium phosphate cement, characterized in that the solution contains a fluoride selected from the group consisting of NaF, KF, NH ₄ F and mixtures thereof.