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Beta-tricalcium phosphate(β-TCP) coating layer is known to be resorbed much faster than hydroxyapatite(HA), however, there has been no report to explain the exact reason of these results. Eighty titanium discs, coated with HA(n=40) or β-TCP(n=40) by dip and spin coating method, were divided into 2 subgroups respectively; Dissolution(D, n=20) and osteoclast culture(C, n=20). The coated discs in D group were immersed in the cell culture media for 5 days, whereas, in C group, osteoclasts were seeded on the specimens and cultured for 5 days. After simple dissolution test, β-TCP coating layer showed much more cracks and denudation as compared to HA. In osteoclast culture group, mean area fraction of resorption pits in HA-C group was 11.62%, which was significantly higher than that of 0.73% in β-TCP-C group(p=0.001). In conclusion, the resorption mechanisms of HA and β-TCP coating layers were different each other in vitro study. The coated β-TCP was degraded mainly by dissolution and separation from implant, on the other hand, the HA coating layer was resorbed by osteoclastic activity.

A edible cuttlefish(Zoological name : Sepia esculenta) bone has a porous structure with all pores interconnected The purpose of this research is to develop porous hydroxyapatite prepared by hydrothermal treatment from cuttlefish bone and evaluate the biocompatibility using undecalcified materials through the in-vivo test of rabbits. In this study, the phase and substructure of a porous hydroxyapatite, prepared by hydrothermal treatment using edible cuttlefish bone as a calcium source, has been confirmed by X-ray diffractometer and scanning electronic microscope. After preparing the specimens with 5mm diameter and 7mm length, the specimens were implanted into the femoral condyles of rabbits. Each rabbits were sacrificed at each time period of 1, 2, 3, 4 weeks after operation, respectively and the stained section was examined by a transmission light microscope. The X-ray diffraction patterns of the edible cuttlefish bone was confirm for aragonite phase and of the sample after hydrothermal treatment showed mostly into hydroxyapatite phase. There was more bone density increase in porous HA rod around implant site than natural edible cuttlefish bone. Because the edible cuttlefish bone is a very pure and good calcium source, porous hydroxyapatite developed from this study is expected to be a biomaterial having a good biocompatibility to be used as a suitable bone substitute.

We observed the cytotoxicity of human bone marrow stromal cells(hBMSCs) by microparticles of bioactive glass with four particle groups(same chemical composition-45S5 but produced by two different manufacturer and two different size groups). In vivo test using rat calvaria were also carried out. The apoptosis rates of all small particle groups(10-20 ㎛) were increased than large(500-700 ㎛ or 200-900 ㎛) particle groups in any culture time and any amount of particles with statistical significance. In vivo study we observed pathologic signs such as macrophages and foreign-body giant cells in rat calvaria by micro-particles of bioglass. Small(10- 20 ㎛) sized particles induced foreign body reaction and bone resorption. There was proliferation of macrophages and cells in large number. But in large particle groups, only fibroblasts were surrounding the particles. The micro-particles of bioglass induced apoptosis of hBMSC and foreign body reaction in calvaria of rat, therefore micro-particles of bioglass may cause osteolysis if used in replacement arthroplasty.

Titanium alloy(Ti-6Al-4V, Samsung techwin, Korea) rods with diameter of 2.5mm were used as the implant materials. Polymethyl methacrylate(PMMA) bone cements(CMW, USA) were used as bone cement and -tricalcium phosphate(TCP)-based bone filler powder was used as osteoconductive additives. Hydroxyapatite(HA) was the desired end product after hydrolysis of the -TCP-based bone filler powder mixed with the blood. In animal study using rabbits, we divided the group into A, B, C and D. Rabbits were sacrificed at 1, 3, 9 weeks after implantation and the affinity index and bone density were calculated. X-ray diffraction patterns of HA formed by hydrolysis of -TCP-based bone filler powder showed higher and higher intensity in HA peak with increase of time period. There was more bone density increase in the group B and D containing - TCP-based bone filler powder around implant site than in the group A and C(p