Papers by Author: Yasushi Suetsugu

Abstract: Unidirectional porous hydroxyapatite (UDPHAp) was developed which has microstructure in that cross sectionally oval pores 100 ~ 300µm in diameter penetrate through the material, and that is suitable for osteogenesis and angiogenesis.The porosity of the UDPHAp was 75 % and the compression strength was 14 MPa. A cortical bone defect was made at proximal tibia of Japanese white rabbit, and a trapezoidal prisms shaped UDPHAp was implanted. By histlogical evaluation, 2 weeks after implantation, new bone and new capillary was observed inside UDPHAp. Twelve weeks after implantation, new bone formation was observed in 41.6 % of the porous area. The results of this study suggest a great possibility of utilizing it in actual clinical setting as a bone substitution.

Abstract: Porous ceramics of hydroxyapatite was fabricated utilizing the crystal growth of thin ice columns parallel to one another in gelatin gel containing hydroxyapatite nanoparticles. The obtained ceramics possessed unidirectional pore channels with a porosity of around 75% and showed compressive strength of up to 13.1 MPa. As control materials, porous hydroxyapatite ceramics with a directionless pore structure were also fabricated by isotropic freezing and compared with the unidirectional samples regarding compressive strength and tissue reaction in vivo. Although the porosity and pore size distribution were similar, the compressive strength and new bone formation ability of the unidirectional samples were significantly greater than those of the random structured porous ceramics.

Abstract: Single crystals of AB-type carbonate apatite were grown by a CaCO3-Na2CO3 flux method under high pressure of Ar gas. The crystals obtained were hexagonal prismatic elongated along the c-axis with the length of 2mm and the diameter of 0.3mm at a maximum. Chemical formula was Ca8.8Na1.2[(PO4)4.8(CO3)1.2]CO3 and the space group was hexagonal P6 with cell parameters a = 0.9379(2)nm, c = 0.6935(1)nm. The detailed crystal structure determined with a reliability factor Rw = 0.047 indicated that the triangular plane of carbonate ion occupying B-site was slanted off the crystallographic mirror plane and the angle of the carbonate triangle with the mirror plane varied depending on Na-substitution of adjacent Ca sites whilst the A-site carbonate ion was parallel to the c-axis.