Nobel bone regeneration system using carbonate apatite-coated carbonate calcium in vivo

Abstract

Statement of the Problem: Effective bone regeneration system requires artificial bone substitutes to replace bone. We developed carbonate apatite (CAp) blocks, which is a component of in vivo bone, by using a new procedure. We have already reported that CAp blocks receive absorption by osteoclasts just like in vivo bone and induce effective bone replacement[1]. Here, we further investigated modified CAp granules, which could be controlled with its absorption. Materials and Methods: CAp granules were prepared by using dissolution-precipitation reaction from carbonate calcium (CaCO3) as a precursor[2]. During that reaction, we were able to get the intermediate block, ‘‘carbonate apatite coated carbonate calcium’. The degree of coating with CAp was measured by X-ray diffraction (XRD), then 10% and 30% CAp-coated CaCO3 were prepared. Sixteen rabbits were subjected to bone regeneration assay. We examined 5 groups, 1) Sham group, 2) CaCO3 group, 2) 10% CAp-coated CaCO3 (10% CAp) group, 3) 30% CAp-coated CaCO3 (30% CAp) group, 4) CAp group. Cylindrical bone defects (F5.0 mm 8.0 mm) of rabbit femurwere formedbyusing dental trephinebar. Those rabbits were sacrificed at 4 and 8 weeks after material implantation surgery and analyzed by means of microcomputed tomography (microCT; Latheta LCT-200, ALOKA). Histological observation (MMA embedded; Villanueva-Goldner staining, Toluidine blue staining) was used to quantify new bone volume at the defect site. Methods of Data Analysis: For quantification of the degree of absorption of those granules in rabbit bone defect study (n=3/group), the sacrificed samples at 4 and 8 weeks after operation were scanned by microCT. After standardizing the images, the area of granules was evaluated with Photoshop CS5.1 (Adobe). For quantification of new bone volume, we calculated the area of new bone in five random images/group (40X-magnification) using ImageJ in toluidine blue stained sections. For