|Budget Amount *help
¥3,700,000 (Direct Cost : ¥3,700,000)
Fiscal Year 1999 : ¥1,700,000 (Direct Cost : ¥1,700,000)
Fiscal Year 1998 : ¥2,000,000 (Direct Cost : ¥2,000,000)
Conventional apatite cement (c-AC), and fast-setting apatite cement (fs-AC) and anti-washout apatite cement (aw-AC) which we developed are epoch-making organism activity cement which shows excellent tissue affinity and osseous conduction, since their hardening body becomes the apatite. However, c-AC induces the inflammation in spite of not happening in fs-AC when the stress was taken in the paste condition in the cement. Then, the purpose of this research is to examine the indication in the clinic of apatite cements by elucidating the condition for showing tissue affinity which these apatite cements are excellent.
At first, to understand the cause of an inflammatory response to c-AC when its paste, not the set mass, was implanted subcutaneously in a rat several apataite powders were implanted subcutaneously in the rat. Although the set c-AC showed excellent tissue response, all apataite powders caused an inflammatory response even though there was a difference in the degree of the infla
mmatory response. The inflammatory response was severer in the order of dicalcium phosphate anhydrous (DCPA)>tetracalcium phosphate (TTCP)>mixture of TTCP and DCPA, i.e., powder phase of AC>crushed set c-AC. In addition, the apatite cement variously was buried in defective part of bone of the hemorrhage condition, and tissue affinity was examined. As the result, the excellent biocompatibility was shown without causing the inflammation, even if these cements were buried in the bone defect of the hemorrhage condition. Especially, not inflammatory reaction but sever foreign body reaction was caused by any cement powder which flew in the circumference without hardening. However, it is disadvantageous that c-AC does not harden, when it touches the blood. Then, it is considered that the newly formed bone happened in the groove without hardening in the one lump after c-AC filling, and the replacement to the bone became frequent in order to surround the cement by the osteoblast from the cement inside. As a result, if it is considered from the stability in vivo, it is understood that the cement of which the set time is short, and which does not washout even if the blood is contacted, is excellent.
We concluded, therefore, that AC shows excellent tissue response only when it is set to form apatite mass, and is difficult to induce the inflammation. Thus, AC should be used for the regions which does not generate a collapse of the cement after the implantation, or AC in which a collapse is not generated should be used, even if it is implanted in the region. Less