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Periimplantitis is an inflammation similar to periodontitis, and is caused by biofilms formed on the surface of dental implants. Application of plasma on biomaterials has been reported to decrease the initial adhesion of microorganism by causing chemical changes without changing the surface morphology. The purpose of this study is to evaluate the effect of inhibition of biofilm formation on the elapsed time after plasma treatment. Non thermal plasma generator (PGS-200 Plasma generator, Expantech Co., Korea) was applied to the specimens. The elapsed time in the atmosphere was set to 5 immediately after treatment, after 30 minutes of treatment, after 60 minutes of treatment, after 90 minutes of treatment. Surface property change with the elapsed time in the atmosphere after plasma treatment were confirmed by X-ray photoelectron spectroscopy and contact angle. Inhibition of biofilm formation was evaluated by the fluorescent nucleic acid staining. It was confirmed that the chemical composition and bonding state of the surface changes as the elapsed time in the atmosphere increases after plasma treatment. The adhesion of Porphyromonas gingivalis was the lowest immediately after plasma treatment, and increased again with increasing elapsed time in the atmosphere after plasma treatment. As a result of this study, it was confirmed that elapsed time in the atmosphere is a very important factor for inhibition of biofilm formation.

In this study, we examined the effect of β-tricalcium phosphate (β-TCP) coating on alkali-treated CP Grade II titanium surface via RF magnetron sputtering on osteoblast like cell (MC3T3-E1) viability and bone formation in rat tibia. The specimens were divided into three groups; commercially pure titanium (control group), alkali-treated titanium with nanofiber structure (NF group) and β-TCP coating on alkali-treated titanium with nanofiber structure (TNF group). The surface characteristics of specimens were observed under a field emission scanning electron microscope (FE-SEM), and contact angle was measured. The cell viability was assessed in vitro after 1 day, 3 days and 7 days. Implants of 2.0 mm diameter and 5.0 mm length were inserted into the tibia of rats. After 4 wks, the histomorphometric analysis was performed. Group NF and group TNF showed improved hydrophilicity of Ti. Group TNF showed significantly higher cell viability (P < 0.05) after 7 days. The bone to implant contact (BIC) ratio of the control group, NF group, and TNF group were 32.3%, 35.5%, and 63.9%, respectively. The study results suggested that β-TCP coated alkali-treated titanium surface via RF magnetron sputtering might be effective in implant dentistry due to enhanced hydrophilicity, improved cell response, and better osseointegration.

The aim of this study was to evaluate the response of Streptococcus mutans (S. mutans) via crystal violet staining assay on titanium surface modified by physical vapor deposition/plasma assisted chemical vapor deposition process. Specimens were divided into the following three groups: polished titanium (control group), titanium modified by DC magnetron sputtering (group TiN-Ti), and titanium modified by plasma nitriding (group N-Ti). Surface characteristics of specimens were observed by using nanosurface 3D optical profiler and field emission scanning electron microscope. Group TiN-Ti showed TiN layer of 1.2 microm in thickness. Group N-Ti was identified as plasma nitriding with X-ray photoelectron spectroscopy. Roughness average (Ra) of all specimens had values < or = 0.2 microm (the threshold Ra), which had no effect on bacterial adhesion. No significant difference of S. mutans adhesion was found between the surfaces of control, TiN-Ti, and N-Ti (P > 0.05). Within the process condition of this study, modified titanium surfaces by DC magnetron sputtering and plasma nitriding did not influence the adhesion of S. mutans.

This study examined the effect of the immobilization of the Gly-Arg-Gly-Asp-Ser (GRGDS) peptide on titanium dioxide (TiO2) nanotube via chemical grafting on osteoblast-like cell (MG-63) viability and differentiation. The specimens were divided into two groups; TiO2 nanotubes and GRGDS-immobilized TiO2 nanotubes. The surface characteristics of GRGDS-immobilized TiO2 nanotubes were observed by using X-ray photoelectron spectroscopy (XPS) and a field emission scanning electron microscope (FE-SEM). The morphology of cells on specimens was observed by FE-SEM after 2 hr and 24 hr. The level of cell viability was investigated via a tetrazolium (XTT) assay after 2 and 4 days. Alkaline phosphatase (ALP) activity was evaluated to measure the cell differentiation after 4 and 7 days. The presence of nitrogen up-regulation or C==O carbons con- firmed that TiO2 nanotubes were immobilized with GRGDS peptides. Cell adhesion was enhanced on the GRGDS-immobilized TiO2 nanotubes compared to TiO2 nanotubes. Furthermore, significantly increased cell spreading and proliferation were observed with the cells grown on GRGDS-immobilized TiO2 nanotubes (P < .05). However, there was no significant difference in ALP activity between GRGDS-immobilized TiO2 nanotubes and TiO2 nanotubes. These results suggest that the GRGDS-immobilized TiO2 nanotubes might be effective in improving the osseointegration of dental implants.

This study examined the bone response to titanium dioxide nanotube modified implants. A total of 24 implants were placed in the femur of 4 beagles. Before placement, screw-shaped implants were classified into 3 groups; machined surface (group M), titanium dioxide nanotube modification of the machined surface (group MN) and titanium dioxide nanotube modification of the RBM surface (group RN). The texture morphology was observed via scanning electron microscopy. Animals were euthanized after 4 and 12 weeks of submerged healing and the histologic and histomorphometric analyses were performed. Groups MN and RN showed a significantly higher percentage of mineralized bone than that in group M (p < 0.05). The results of this in vivo study constitute significant evidence that the presence of the titanium dioxide nanotubes enhance osseointegration of implants.