&agr;-TCP/HAP biphasic cement and its preparing process

Compositions: coating or plastic – Coating or plastic compositions – Dental

Reexamination Certificate

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Details

C106S670000, C501S001000, C423S311000, C423S315000, C423S305000

Reexamination Certificate

active

06338752

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a bone filling material biphasic cement of &agr;-TCP/HAP and its process for preparing.
BACKGROUND OF THE INVENTION
For those who have to remove partial bone because of traumas, bone tumors or cysts, proper bone filling materials or cement are necessary to remedy the defect.
Conventional bone filling cement is made from polymers such as acrylic resin and HDPE, but the polymers are not biocompaible with human beings. In view of this, some researchers therefore added calcium phosphates (CPs) into the polymers to improve their biocompatibility, because the CPs such as hydroxyapatite powder (Ca
10
(PO
4
)
6
(OH)
2
, HAP) or tricalcium phosphate powder (Ca
3
(PO
4
)
2
, TCP) are more biocompatible and can directly bind with bone tissue of human bodies. However, the CP powder tended to be enveloped by the polymers, which limited the effects since the CPs couldn't contact with the bone tissue.
Consequently many researchers try to develop the bone filling material only composed of inorganic CPs, e.g., calcium phosphate cement (CPC), because of their better biocompatibility and similar components to human beings'. So far, many CPC systems are being developed, such as tetracalcium phosphate (Ca
4
P
2
O
9
, TTCP), dicalcium phosphate (CaHPO
4
, DCP), octacalcium phosphate (Ca
8
H
2
(PO
4
)
6
. 5H
2
O, OCP) , &agr;-TCP, &bgr;-TCP and HAP.
In view of the development of bone filling materials, the ideal bone filling materials should (a) contain CPs because of its better biocompatibility, (b) provide plasticity at an earlier stage of the filling surgery, and (c) be able to rapidly set after being filled into the defective parts.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a biphasic bone filling material of &agr;-TCP/HAP, which is a kind of calcium phosphate cement (CPC), and can be plastic powder and set rapidly so that it is fit for bone filling surgery.
It is another object of the present invention to provide a process for preparing biphasic cement of &agr;-TCP/HAP, in which a superior bone filling material can be obtained.
It is still another object of the present invention to provide a process for preparing biphasic cement of &agr;-TCP/HAP, in which the composition of biphasic cement of &agr;-TCP/HAP can be controlled.
Biphasic cement of &agr;-TCP/HAP in the present invention primarily comprises &agr;-tricalcium phosphate (Ca
3
(PO
4
)
2
, &agr;-TCP) and hydroxyapatite (Ca
10
(PO
4
)
6
(OH)
2
, HAP). Biphasic cement of &agr;-TCP/HAP in the present invention has a preferred composition as 30-60 wt % of &agr;-TCP and 70-40 wt % of HAP.
Biphasic cement of &agr;-TCP/HAP in the present invention is a kind of calcium phosphate cement (CPC), which can set in human body because different kinds of CPs can be dissolved in water solution and perform segregation. Apatite crystal generated in segregation can interactively set with each other similar to the coagulation of cement. Biphasic cement of &agr;-TCP/HAP in the present invention is a superior cement since it can set rapidly while soaking in water solution.
The process for preparing biphasic cement of &agr;-TCP/HAP in the present invention is to bring the powder mixture of ammonium phosphate (AP) and hydroxyapatite (HAP) to thermal process, and then biphasic cement of &agr;-TCP/HAP is obtained. In the process of the present invention, the composition of biphasic cement of &agr;-TCP/HAP can be controled by adjusting the weight percentage of AP powder and HAP powder respectively.


REFERENCES:
patent: 4938938 (1990-07-01), Ewers et al.
patent: 5017518 (1991-05-01), Hirayama et al.
patent: 5180426 (1993-01-01), Sumita et al.
patent: 5238491 (1993-08-01), Sughara et al.

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