TAKASHI Noriyuki Hokkaido University, Medical&Dental Hospital, Research Associate, 医学部・歯学部附属病院, 助手 (40312376)
TOTSUKA Yasunori Hokkaido University, Graduate School of Dental Medicine, Professor, 大学院・歯学研究科, 教授 (00109456)
UO Motohiro Hokkaido University, Graduate School of Dental Medicine, Associate Professor, 大学院・歯学研究科, 助教授 (20242042)
AKASAKA Tsukasa Hokkaido University, Graduate School of Dental Medicine, Research Associate, 大学院・歯学研究科, 助手 (00360917)
YOKOYAMA Atsuro Hokkaido University, Medical&Dental Hospital, Lecturer, 医学部・歯学部附属病院, 講師 (20210627)
|Budget Amount *help
¥12,100,000 (Direct Cost: ¥12,100,000)
Fiscal Year 2003: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2002: ¥9,200,000 (Direct Cost: ¥9,200,000)
[Purpose]In dental material the powder/liquid method is abundantly used and abrasion powder arises in the sliding part of artificial joint. To study the effect of powders on health the size dependence of fine particles on biocompatibility was investigated by cell functional test and implantation test.
[Method] Monodispersed particles were extracted by sedimentation for the size 0.5, 3, 10μm and by ultrafiltration for less than 300nm. The particles were thus prepared with the same size for different materials.
[Size dependence] In cell functional test using the human neutrophil, periodontal ligament cell and rat macrophage, the cell survival rate was lowered and the emission of LDH, oxygen radical, cytokines TNF-α, IL-1β, IL-8, M-CSF increased as particle size became smaller, for Ti, Fe, Ni(each 500nm ; 3,10, 50, 150μm), TiO_2(30, 60, 300, 500nm ; 2μm), polylactic acid (1, 13μm). Especially, for the case of smaller than 10μm where phagocytosis was induced, the effect was remarkably pronou
nced. The stimulatibility of these effects is lower by about 1/100〜1/1000 than the intracellular toxicity.
[Material dependence]Both Ti whose ionic dissolution was negligible, confirmed by the ICP elemental analysis, and Fe, much more dissolvable, showed the similar size dependency. In Ni, cell survival rate was lower, emission of oxygen radical and cytokine was larger, the cell destruction was observed by microscopy, which was due to the stronger cytotoxicity of Ni.
[Conclusion]In animal implantation test, Ti particles showed biocompatibility for the size larger than about 100μm, and inflammation for smaller than 50μm. For less than 10μm phagocytosis was induced and inflammation was continued for the long term. For the biocompatibility in the material with a macroscopic size the material-dependent, chemical effect through dissolved ions is generally dominant. For the range of μm〜nm, the material-independent, physical size effect origined from the relative size relation between particles and cell/tissue becomes tangible, even for the bioactive and bioinert materials. Less