Enhanced funtion of human periodontal ligament cells cultured on nanoporous titanium surfaces

Biological integration of implant to surrounding tissue is important process as it determines its clinical success and attraction of bone cells. Also, in order to reduce the problems of implant-related infections, many kinds of the surface treatment on titanium have been proposed. The formations of TiO₂ nanotubes on the titanium have been widely studied to improve the biocompatibility of the surface, and silver nanoparticles have been known to exhibit the antibacterial efficacy. The purpose of this study was to carry out surface treatment on titanium and observe response of human periodontal ligament (hPDL) cells using combination of nanotube formation and silver nanoparticles treatment. Surface modification of titanium was performed in two different ways. One was nano-porous anodic oxidation (NAO) prepared by HF solution and the other was magnetron sputtering incorporated with silver nanoparticles on nanoporous anodic oxidation (S-NAO). The surface morphology and characterization was analyzed by Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive Spectroscopy (EDS). Inflamed hPDL cells were isolated from the inflamed hPDL tissue obtained from intra-bony defects during flap surgery, and characterized by colony-forming unit assay, fluorescence-activated cell sorting, and mRNA expression in comparison with healthy hPDL cells obtained from extracted teeth for orthodontic purpose. The hPDL cells attachment and its morphological features were observed by FE-SEM. WST1 assay was performed to assess its cytotoxicity and cell proliferation. From the FE-SEM analysis, nano-porous and silver nano particles on surface of titanium were observed. The nanoporous structures were well formed with diameter of 100nm. hPDL cells were well attached at NAO and S-NAO treated surfaces and result of WST-1 assay indicated that NAO and S-NAO treated surfaces have no cytotoxicity to hPDL cells. However, cell proliferation rate was little higher with NAO treated surface then S-NAO. Our findings showed that NAO treated titanium surface samples provided an attractive substrate for hPDL cells adhesion, proliferation and differentiation.