JP3000719B2 - Hydraulic calcium phosphate cement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic calcium phosphate cement which can be used as a filling material for a bone defect and a bone cavity or a filling material for a tooth root canal.

[0002]

2. Description of the Related Art Hydraulic calcium phosphate is useful as a restoration material for teeth and bones because it is converted into a compound similar to the main components of teeth and bones in a living body by setting and hardening. It is known to be useful as an adsorbent for harmful organic or inorganic ions.

Conventionally, as the above-mentioned hydraulic calcium phosphate, a calcium phosphate cement using a combination of salts and a dilute acid as a hardening solution in JP-A-59-88351, and JP-A-60-253454. A calcium phosphate cement using an acidic solution containing an unsaturated carboxylic acid polymer is disclosed. However, in the case of the hydraulic calcium phosphate, there is a problem in that the hardening solution is strongly acidic until the hardening of the cement is completed, causing considerable irritation to the living body. There is also a problem that the pH is lowered due to elution of, and as a result, the living body is stimulated.

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

[0005] However, the hydraulic calcium phosphate comprises α-type tribasic calcium phosphate and dibasic calcium phosphate dihydrate in a Ca / P molar ratio of 1.20 to 1.4.
It is characterized by mixing at a ratio of 7 and, when left in water for a long time, its strength is deteriorated. Therefore, there is a very high risk of deterioration and destruction in a living body, and the curing time is slightly high. There is a problem of being slow.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a water which can be rapidly cured at a pH around neutrality and which has excellent biocompatibility without deterioration over a long period of time. It is to provide a hard calcium phosphate cement.

Another object of the present invention is to provide a hydraulic calcium phosphate cement having a short setting time.

[0008]

According to the present invention, tribasic calcium phosphate and monobasic calcium phosphate are combined with Ca / P
A hydraulic calcium phosphate cement comprising a powder and a liquid, which are mainly composed of a mixture obtained by mixing at a molar ratio of 1.400 to 1.498, wherein the third calcium phosphate is α-type third calcium phosphate And a β-type tribasic calcium phosphate.

Hereinafter, the present invention will be described in more detail.

[0010] The hydraulic calcium phosphate cement of the present invention is characterized in that a mixture obtained by mixing monobasic calcium phosphate and specific tribasic calcium phosphate at a specific Ca / P molar ratio is used as a main component of the powder. .

In the hydraulic calcium phosphate cement of the present invention, the tribasic calcium phosphate used as a dust component is a mixture of α-type tribasic calcium phosphate and β-type tribasic calcium phosphate. The α-type tribasic calcium phosphate in the mixture reacts with the monobasic calcium phosphate to produce and harden the octacalcium phosphate so as to exert the initial strength of the obtained cement hardened body,
Β-type tricalcium phosphate, whose reaction rate is much slower than that of type-tricalcium phosphate, is a component that reacts with time so as to gradually exert the strength of the obtained cement hardened body, By using a mixture of and a β-type tricalcium phosphate, it is possible to prevent deterioration of the strength of the obtained cement hardened body.

The α-type tricalcium phosphate and the β-type tribasic
The mixing ratio with calcium phosphate is 97: 3 by weight ratio.
It is preferred to be in the range of 50:50. When the mixing ratio of the β-type tribasic calcium phosphate is less than 3, the effect of preventing the deterioration of the strength cannot be obtained, and when the mixing ratio is more than 50, the initial strength decreases, which is not preferable.

In order to prepare the α-type tribasic calcium phosphate and the β-type tribasic calcium phosphate, for example, an equimolar mixture of calcium pyrophosphate and calcium carbonate is used. In addition, in the case of β-type tricalcium phosphate, a calcination temperature is preferably 900 ° C. to 1100 ° C., and a dry method in which a solid phase reaction is performed, or a tertiary calcium phosphate slurry synthesized by, for example, dropping phosphoric acid into slaked lime, is dried, It can be obtained by a wet method of baking at preferably 1200 ° C. or more for α-type calcium phosphate and preferably at 900 to 1100 ° C. for β-type calcium triphosphate.

[0014] The tribasic calcium phosphate synthesized by the wet method has higher hydration activity, can shorten the setting time of cement, and has a higher strength than the tribasic calcium phosphate synthesized by the dry method. Since it becomes high, it can be preferably used. At this time, both the α-type tricalcium phosphate and the β-type tricalcium phosphate can be synthesized by a wet method.
It is preferable to use at least α-type tribasic calcium phosphate synthesized by a wet method.

In the present invention, the first component used as a powder component
The calcium phosphate is not particularly limited, but preferably includes commercially available monobasic monobasic calcium phosphate and the like.

In the present invention, the mixing ratio of the tribasic calcium phosphate used as the powder component and the first calcium phosphate is from 1.400 to 1.400 in terms of a Ca / P molar ratio.
498 must be mixed. Said C
When the a / P molar ratio is less than 1.400, a large amount of unreacted monobasic calcium phosphate remains after kneading and the strength decreases, and when it exceeds 1.498, it takes a long time to cure. Therefore, it is necessary to set the above range.

The hydraulic calcium phosphate cement of the present invention may further contain dibasic calcium phosphate as a main component of the powder. The dibasic calcium phosphate is a component that reacts with α-type tribasic calcium phosphate in the presence of water to generate and harden octacalcium phosphate, and is a component that further improves the strength of the hardened cement. As the second calcium phosphate, commercially available second calcium phosphate
Preferred examples include calcium phosphate dihydrate. The reaction proceeds most rapidly at pH 6-8.

In this case, the mixing ratio of the dicalcium phosphate is preferably 10% by weight or less, particularly preferably 5% by weight or less based on the whole powder. If the mixing ratio of the second calcium phosphate exceeds 10% by weight, the strength is undesirably reduced.

Further, an X-ray contrast agent such as hydroxyapatite, β-type calcium phosphate, barium sulfate or the like having high biocompatibility may be added to the powder as needed. As the liquid agent used in the present invention, water alone is sufficient, but mucopolysaccharides such as sodium chondroitin sulfate and sodium hyaluronate are used to further improve operability, and sodium succinate is used to shorten the curing time. Or a water-soluble sodium salt such as sodium lactate.

The mixing ratio of the powder and the liquid is preferably in the range of 300 to 50: 100 by weight. If the mixing ratio of the powder is less than 50, it takes a long time to cure, and if it is more than 300, it is too hard at the time of kneading and the operability is undesirably reduced.

[0021]

The hydraulic calcium phosphate cement of the present invention contains α-type tribasic calcium phosphate and monobasic calcium phosphate as β-type tribasic calcium phosphate as a powder, so that the strength is not deteriorated for a long time, and Area pH
In addition, it can be cured within a practical time, and has excellent biocompatibility. Further, in the calcium phosphate cement of the present invention, since the powder can further contain dicalcium phosphate, a hydraulic calcium phosphate cement having higher strength can be obtained. Therefore, it is useful as a filling material for a bone defect and a bone cavity or a filling material for a tooth root canal.

[0022]

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0023]

Example 1 A mixture of α-tribasic calcium phosphate and β-tribasic calcium phosphate in a weight ratio of 80:20 was used as a tribasic calcium phosphate and monobasic calcium phosphate monohydrate (Wako Pure Chemical Industries, Ltd.) And food additives) and Ca /
P molar ratio of 1.40, 1.43, 1.46, 1.4
The mixture was mixed to obtain 9,1.498 to prepare a cement powder. Next, 60 parts by weight of water was added as a liquid to 100 parts by weight of the obtained cement powder, and the mixture was kneaded and cured. When the pH of the cement paste at the time of hardening was measured using a litmus test paper, the pH was 6
８8. The setting time and the compressive strength of the obtained cured cement were measured. Table 1 shows the results.
The hardening time was in accordance with JIS R5201, and the compressive strength was measured using a universal testing machine manufactured by Instron Co., Ltd. after immersing the hardened cement (7 mmφ, 14 mmL) in an artificial body fluid for 3 days, taking it out and getting wet. .

[0024]

Comparative Example 1 The curing time and compressive strength were measured in the same manner as in Example 1, except that the α-type tricalcium phosphate and the monobasic calcium phosphate were changed to Ca / P molar ratios of 1.33 and 1.499. Table 1 shows the results.

[0025]

[Table 1]

[0026]

EXAMPLE 2 The third calcium phosphate used in Example 1 and the first calcium phosphate had a Ca / P molar ratio of 1.4.
9, 2% by weight, 5% by weight, 7% by weight based on the whole powder material of dicalcium phosphate (manufactured by Wako Pure Chemical Industries, Ltd .; dicalcium phosphate dihydrate, special grade). And 10% by weight and 12% by weight, respectively, to obtain a cement powder. Next, 100 parts by weight of the obtained powder and 60 parts by weight of water as a liquid were kneaded and hardened. When the pH of the cement paste at the time of hardening was measured using a litmus test paper, the pH was 6
８8. The setting time and the compressive strength of the obtained cement hardened body were measured in the same manner as in Example 1. Table 2 shows the results.

[0027]

[Table 2]

[0028]

Example 3 The mixing ratio of β-type tribasic calcium phosphate in tribasic calcium phosphate was as shown in Table 3, and the tribasic calcium phosphate and monobasic calcium phosphate were Ca
It mixed so that / P molar ratio might be 1.49. Next, 60 parts by weight of a 20% by weight aqueous solution of sodium succinate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added as a liquid to 100 parts by weight of the obtained powder, and kneaded. The compressive strength at the indicated days was measured. Table 3 shows the results.

[0029]

Comparative Example 2 The curing time and compressive strength were measured in the same manner as in Example 3 except that β-type tricalcium phosphate was not contained. Table 3 shows the results.

[0030]

[Table 3]

[0031]

Example 4 The same procedure as in Example 4 was carried out except that the mixing ratio of β-type tribasic calcium phosphate in the tribasic calcium phosphate was as shown in Table 4, and 3% by weight of dibasic calcium phosphate was added to the whole powder. Then, the curing time and the compressive strength in the number of days shown in Table 4 were measured. Table 4 shows the results.

[0032]

Comparative Example 3 Curing time and compressive strength were measured in the same manner as in Example 4 except that β-type tribasic calcium phosphate was not contained. Table 4 shows the results.

[0033]

[Table 4]

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) A61L 27/00 A61K 6/00-6/06

Claims (2)

(57) [Claims] 1. A powder containing a mixture obtained by mixing a third calcium phosphate and a first calcium phosphate such that the Ca / P molar ratio is 1.400 to 1.498, and a liquid. A hydraulic calcium phosphate cement, wherein the third calcium phosphate is a mixture of α-type tricalcium phosphate and β-type tricalcium phosphate. 2. The hydraulic calcium phosphate cement according to claim 1, further comprising dicalcium phosphate as a main component of the powder of the hydraulic calcium phosphate cement.