In vitro implant materials have the mechanical characteristics, the biocompatibility and biofunctionability to maintain the stable function. Till now, the compatibility of experimental animal, and osteoblast or osteosrcoma cell lines have been mainly reported. Recently it must be necessary to examine the compatibility of normal human osteoblastic cell lines on titanium surface. We used two methods: in vitro and in vivo study.
NHOst cell lines were cultured under DMEM containing 10% FBS, and examined by inverted microscopy. These cells attached to the surface of titanium plates were fixed with 2.5% paraformaldehyde, dehydrated, coated with gold, and examined by SEM, Growth curve, and adhesion assay according to 2, 5, 10% FBS concentration, respectively were done. At 5th, 8th, 11th weeks, bone around titanium were fixed with 10% neutral formalin solution, dehydrated, and embedded with Spurr low viscosity resin. For LSM, rabbits were injected with 30mg/Kg calcein blue(CB) and 50mg/Kg alizarin red(AR) before on the 1, 2 week of sacrification, respectively. After the specimen was cut by 500㎛ with slow diamond wheel saw, these were grinded up to 100-150㎛, examined with LM, and PM, and LSM. Carbon coated resin sections were examined by REM, and qualitatively analyzed for Ca and P deposition by EPMA. The obtained results were as follows.
1. In inverted microscopy, NHOsts were attached the surface of titanium at 3rd days, showed multilayer at 2nd wks and extracellular mineralized matrix at 4th wks.
2. In SEM, NHOsts with long processes were interconnected each other at 2nd wks, and showed thicker multilayer at 4th wks.
3. Doubling time was about 30 hours, and adhesion activity was the highest under DMEM containing 10% FBS.
4. In toluidin blue staining new bone was tightly attached to the surface of titanium at 5th wks, and new bone was well demarcated from compact bone at the 8th wk, and well calcified bone with Haversian canals and osteocytes at the 11th wk were seen. PM showed new bone as yellow or blue color around titanium at 5th wks, and new bone as yellow color at the 11th wk.
5. In REM, there was dark grey color in new bone at 5th and 8th wks, while similar color to that of compact bone at the 11th wk.
6. In LSM, AR and CB labelled bone were seen around titanium, but labelled bone was decreased at 8th and 11th wks and labelled osteons were increased at the 11th wk.
7. In EPMA, Ca and P deposition in new bone around titanium at 8th and 11th wks were gradually increased in comparision with that at 5th wks, but Ca deposition at 11th wks was lower than that of compact bone.
From the aboving results, NHOst cell lines showed the highest adhesion activity in DMEM containing 10% FBS, and mutilayer growth. There were well osseointegration between the surface of titanium, and increased bone formation from 5th to 8th wks, and lower Ca deposition than that of compact bone at 11wks. It was suggested that titanium plate showed the biocompatibility to NHOst, and new bone at 11th weeks showed less mineralization compared to compact bone.
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