The Biological Behaviour Of Gingival Fibroblasts On Different Titanium Alloy (Ti6Al4V) Surface Topographies

Objective: The success of dental implantation is not only depend on theexcellent osseointegration, but also depended on a favorable soft tissueintegration of the implant neck part. The topography of implant necksurface is one of the most important factors which can affect the softtissue attachment. The purpose of this study is to evaluate the effect ofthree different titanium alloy surface characteristics on the biologicalbehavior of fibroblasts(L929),and to find a proper surface which canpromote the proliferation and attachment of the fibroblasts and enhancethe soft tissue integration, meanwhile, provide a guidance for thedesignation of the implant neck part.Methods: Three different titanium alloy surface topographies werecreated by machining(M),direct current electrochemical etching(DC) andalternating current electrochemical etching(AC) respectively. Theirsurface topographies were investigated using field emission scanningelectron microscopy(FSEM). Mouse L929fibroblasts were seed ondifferent surfaces. The attachment and biocompatibility of cells wereexamined through acridine orange staining fluorescence. Theproliferation of cells was measured using MTT assayResults: The machined group had a relatively smooth surface with isotropic grooves, the direct current electrochemical etching group had amicro-scale rough surface with micro-submicro holes and the altercurrent electrochemical etching group had a micro-submicro-nanohierarchical structure. The acridine orange staining fluorescence resulthad shown that all the three titanium alloy specimens have a goodbiocompatibility. The fibroblasts attachment of the M surface was weakerthan the DC and AC surfaces, and the AC surface had the best fibroblastsattachment. The MTT assay shown that the proliferation of fibroblasts onthe AC and DC surfaces was superior to the M surface at the2~7day andthe proliferation of fibroblasts on the AC surface was higher than the DCsurface at the3~5day. At the3rd day,the cells on the machined surfacewere thin and flat, similar to round, with a parallel orientation and thecells did not spread very well. At high magnification, the cells had shortpseudopodia. The cells on the DC surface were spread well and hadlonger pseudopodia than the machined surface with some pseudopodiaputting in the pore. On the AC surface, some cells were falling in themicro pore, the cells spread better than the DC surface and thepseudopodia were much longer and stronger. Some of the pseudopodia ofadjacent cells were fused together. At the7thday, the extracellular matrixon three group surfaces were increased significantly. The M group surfacewere covered by a mass of extracellular matrix, the cell were round andwith a poor spread. The pseudopodia were longer and increased than the 3rdday. On the DC group, the micro pore were covered by a mount ofextracellular matrix, the cells were flap and spread totally. There are somenew round cells which were sitting on the extracellular matrix. Theprocessus and pseudopodia of the cell were attaching on the micro poretightly. The cells on the AC group were much more flap and irregular.The body of the cells were sitting in the micro pore and had the longestprocessus pseudopodia with some pseudopodia putting in the distant poreand could form three-dimension structure suspended in midair.Conclusion: The AC surface with the micro-submicro-nano hierarchicalstructure had a good biocompatibility, which can promote the attachmentproliferation of the fibroblast and the secretion of extracellular matrix.