# Effect of Plasma Treatment of Titanium Surface on Biocompatibility
## 4 Discussion  
The aim of this study was to establish whether RBM cells respond differently to titanium implants that have undergone surface modification by plasma treatment. The results showed that adhesion and osteogenic differentiation increased in cells grown on plasma-treated disks compared to those raised on untreated disks. Titanium disks modified by plasma treatment promoted RBM cell adhesion and osteogenic differentiation. Titanium implant surface properties, such as chemistry, wettability, and morphology, affect osteoblast proliferation, extracellular matrix and local factor production, and stimulation of the osteogenic microenvironment [30; 31]. Thus, it is important to understand how material surface cleaning affects these physicochemical properties [32]. The optimal surface characteristics for clinically placed dental implants and orthopedic endoprostheses have not yet been determined. However, it is clear that removing contaminants from the material surface and imparting hydrophilicity to it are both useful [33; 34; 35]. In the present study, we investigated changes in titanium surfaces treated with atmospheric-pressure, low-temperature plasma. The device generating these conditions utilizes mechanical piezoelectric resonance to amplify electrical energy and generate high voltage. In this way, it ionizes the active gas or the surrounding atmosphere and produces plasma. Conventional plasma devices require vacuum and processing is both constrained and costly. In contrast, the piezobrush device used in the present study was compact and readily generated plasma. Therefore, it is suitable for chairside use in dentistry. Figure 10: Calcium deposition of titanium and plasma-modified titanium. Mineralization was greater in the cells on the plasma-treated specimens than the untreated titanium disk. Figure 9: Alkaline Phosphatase (ALP) activity of titanium and plasma-modified titanium. There were major differences in ALP activity between the plasma-treated and titanium surfaces at days 7 and 14. There were no perceivable differences in the SEM or SPM analysis between the untreated surface and that treated with atmospheric low-temperature plasma. On the other hand, the contact angle experiment test disclosed that atmospheric low-temperature plasma treatment increased the wettability of the titanium relative to that of the control [36; 37]. Atmospheric-pressure, low-temperature plasma treatment introduces hydrophilic functional groups to resinous organic materials and inactive inorganic substances such as zirconia and titanium [38]. Adhesion between cells and proteins increases with wettability. The XPS analysis revealed that the atmospheric pressure, low-temperature plasma treatment effectively removes the carbon content derived from organic contaminants on the material surface. Under atmospheric pressure, low-temperature plasma, high-energy ions collide with the sample surface, dissociate the carbon bonds in the organic contaminants, and cause them to volatilize. Analysis of the surface of the pure titanium material showed that low-temperature, atmospheric-pressure plasma treatment cleaned it, increased its hydrophilicity, and improved its biocompatibility. In the in vitro culture media and in vivo biological fluids, all implant surfaces are immediately covered with a layer of protein. This interface modulates a cascade of cellular responses and behaviors [38]. To examine the relationships among implant surface properties, opsonization, and phagocytosis in vivo, phagocytic experiments were conducted on a cell line grown in a culture medium supplemented with BSA and human opsonizing serum factors [39]. Albumin is the most abundant plasma protein. It inhibits the adsorption of proteins that stimulate inflammation and bacterial colonization [39; 40]. In the present study, the test group adsorbed more albumin than the control group. Indirect improvement of surface topography could involve the adsorption of proteins or ions that act as bridges between the nanostructured surface and the cells [41].