| Research Abstract |
The peri-implant connective tissue fiber could be expected to make a biological seal which serves to prevent the penetration of periodontally pathologic chemical and bacterial substances. In order to those demands, we evaluated extension and spread of fibroblasts and epithelial cells, and oral bacterial adherence and antibacterial activity on surface-modified titanium. The extension and spread of fibroblasts and epithelial bells were critically influenced by the pore size of 1.2-3.0 u.m in diameter on millipore filters. Our observation of in vitro experiment also suggest that a range of 50 to 100 μm in pore size is most critical for the connective tissue cells to migrate and orientated right angle to the implant surface similar tosharpey's fibers may influence a biological seal around the implant. This is the reason why we create the pores around the neck of the implant surface.
The influence of surface modifications to titanium on the initial adherence of P. gingivalis ATCC33277 and A.
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actinomycetemcomitans ATCC437 1 8 was evaluated. Surface modifications were carried out with dry processes that including ion implantation (Ca^+, N^+, F^+), oxidation (anode oxidation, titania spraying), ion plating (TiN, alumina),and ion beam mixing (Ag, Sn, Zn, Pt) with Ar+ on polished pure titanium plates. Comparatively large amounts of.P.gingivalis and A. actinomycetemcomitans adhered to polished titanium plates. The degree of P. gingivalis adhesion showed a positive correlation with surface energy and the amount of calcium-ion adsorption. Both P.gingivalis and A. actinomycetemcomitans adherence increased on calcium-implanted surfaces compared to polished titanium surfaces, whereas P. gingivalis adherence was remarkably decreased on alumina-coated surfaces. These findings indicate that titanium implants exposed to the oral cavity requiresurface modification to inhibit the adherence of oral bacteria, and that surface modification with a dry process is useful in controlling the adhesion of oral bacteria as well as ensuring resistance against wear. The antibacterial effect of surface modifications to titanium on those bcteria was also evaluated. F+-implanted specimens significantly inhibited the growth of both P. gingivalis and A. actinomycetemcomitans. than the polished titanium. The other surface-modified specimens did not exhibit effective antibacterial activity against both bacteria. No release of the fluorine ion was detected from F-Jmplanted specimens under dissolution testing. This result and the characterization of the F^+-implanted surfaces suggested that the possible antibacterial mechanism of the F^+-implanted specimen was caused by the formation of a metal fluoride complex on the surfaces. In addition, F^+-implanted surfaces did not inhibit the proliferation of fibroblast L929-cells. These findings indicate that surface modification by means of a dry process is useful in providing antibacterial activity of oral bacteria to titanium implants exposed to the oral cavity. Less
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