Effects on Antibacterial Activity and Osteoblast Viability of Non-Thermal Atmospheric Pressure Plasma and Heat Treatments of TiO2 Nanotubes.

The aim of this study was to evaluate the antibacterial activity against Porphyromonas gingivalis and osteoblast viability of heat and plasma treatment of TiO2 nanotubes. Specimens were divided into four groups: the Ti (polished titanium), Nano (TiO2 nanotube), NH 300 (heat treated at 300 °C on TiO2 nanotube) and NH 400 (heat treated at 400 °C on TiO2 nanotube) groups. Antibacterial activity and osteoblast viability were evaluated in the four groups according to plasma treatment. Surface adhesion of Porphyromonas gingivalis was evaluated by crystal violet assay. Osteoblast viability was examined by XTT assay. Adhesion of Porphyromonas gingivalis was significantly decreased in the Ti group, Nano group and NH 300 group after plasma treatment (P < 0.05). Osteoblast viability was increased in the NH 400 group in comparison to the Ti group before plasma treatment (P < 0.05). Within the limitations of this study, plasma treatment was found to reduce the adhesion of P. gingivalis but had no influence on osteoblast activation.

Effect on Adhesion of Porphyromonas gingivalis by Titanium Nitride Sputter Coating or Plasma Nitriding of Titanium.

Porphyromonas gingivalis (P. gingivalis) is one of main bacteria that adheres to the surface of dental implants and causes peri-implantitis. The purpose of this study was to observe the surface characteristics of titanium processed with either titanium nitride (TiN) sputter coating or plasma nitriding and to evaluate the subsequent adhesion of P. gingivalis. Specimens were divided into three groups: commercially pure (CP) titanium (control group), TiN sputter­coated titanium (group S), and plasma-nitrided titanium (group P). Surface characteristics such as roughness, morphology, and the formation of a thin TiN film or a nitriding layer were assessed. Adhesion of P. gingivalis in the three groups was determined by means of the crystal violet staining assay, and results were compared with one-way ANOVA, with post hoc comparison using Tukey's test (α = 0.05). Surface roughness values for the control group, group S, and group P were 0.08±0.02 µm, 0.19±0.04 µm, and 0.13±0.02 µm, respectively. In group S, the TiN layer was 1.36±0.1 µm thick, and nitrogen was detected on the surface of the specimens in group P, confirming formation of a nitrided layer. The level of adhesion in group P was significantly higher than that in the control group and in group S (p < 0.05), but there was no significant difference between the control group and group S. Within the limitations of this study, TiN sputter coating did not affect adhesion of P. gingivalis on the titanium surface, whereas adhesion was increased on the plasma-nitrided titanium surface.

Surface Characteristics of Bioactive Glass-Infiltrated Zirconia with Different Hydrofluoric Acid Etching Conditions.

The purpose of this study was to examine the surface characteristics of bioactive glass-infiltrated zirconia specimens that underwent different hydrofluoric acid (HF) etching conditions. Specimens were classified into the following six groups: Zirconia, Zirliner, Porcelain, Bioactive glass A1, Bioactive glass A2, and Bioactive glass A3. Zirliner and porcelain were applied to fully sintered zirconia followed by heat treatment. Bioactive glass was infiltrated into presintered zirconia using a spin coating method followed by complete sintering. All the specimens were acid-etched with 10% or 20% HF, and surface roughness was measured using a profiler. The surface roughness of the zirconia group was not affected by the etching time or the concentration of the acid. The roughness of the three bioactive glass groups (A1, A2, and A3) was slightly increased up until 10 minutes of etching. After 1 hour of etching, the roughness was considerably increased. The infiltrated bioactive glass and acid etching did not affect the adhesion and proliferation of osteoblasts. This study confirmed that surface roughness was affected by the infiltration material, etching time, and acid concentration. For implant surfaces, it is expected that the use of etched bioactive glass-infiltrated zirconia with micro-topographies will be similar to that of machined or sand-blasted/acid-etched (SLA) titanium.