Low Pressure Radio-Frequency Oxygen Plasma Induced Oxidation of Titanium – Surface Characteristics and Biological Effects

Abstract

ObjectiveThis research was designed to investigate the effects of low pressure radio-frequency (RF) oxygen plasma treatment (OPT) on the surface of commercially pure titanium (CP-Ti) and Ti6Al4V. Surface topography, elemental composition, water contact angle, cell viability, and cell morphology were surveyed to evaluate the biocompatibility of titanium samples with different lengths of OP treating time.Materials and MethodsCP-Ti and Ti6Al4V discs were both classified into 4 groups: untreated, treated with OP generated by using oxygen (99.98%) for 5, 10, and 30 min, respectively. After OPT on CP-Ti and Ti6Al4V samples, scanning probe microscopy, X-ray photoelectron spectrometry (XPS), and contact angle tests were conducted to determine the surface topography, elemental composition and hydrophilicity, respectively. The change of surface morphology was further studied using sputtered titanium on silicon wafers. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and F-actin immunofluorescence stain were performed to investigate the viability and spreading behavior of cultivated MG-63 cells on the samples.ResultsThe surface roughness was most prominent after 5 min OPT in both CP-Ti and Ti6Al4V, and the surface morphology of sputtered Ti sharpened after the 5 min treatment. From the XPS results, the intensity of Ti°, Ti2+, and Ti3+ of the samples’ surface decreased indicating the oxidation of titanium after OPT. The water contact angles of both CP-Ti and Ti6Al4V were increased after 5 min OPT. The results of MTT assay demonstrated MG-63 cells proliferated best on the 5 min OP treated titanium sample. The F-actin immunofluorescence stain revealed the cultivated cell number of 5 min treated CP-Ti/Ti6Al4V was greater than other groups and most of the cultivated cells were spindle-shaped. ConclusionsLow pressure RF oxygen plasma modified both the composition and the morphology of titanium samples’ surface. The CP-Ti/Ti6Al4V treated with 5 min OPT displayed the roughest surface, sharpest surface profile and best biocompatibility.

Effect of different surface treatments on the shear bond strength of luting cements used with implant-supported prosthesis: Anin vitrostudy

“…that the level of energy stabilizes after the initial energy bombardment that occurs during the first 5 minutes of application. 21,26 Most plasma studies have evaluated surface changes using atomic force microscope and profilometer 21,22 ; however, considering that these studies reported changes of less than 1 nm, this study evaluated water contact angle instead.…”

“…37 Oxygen plasma treatment can be performed under different atmospheric pressure conditions and with various types of electrically neutral ionized gas as well as using homogenous dielectric barrier discharge, and it has a wide range of applications from industry to medicine. 25,38 Studies examining the effects of oxygen plasma treatment application to titanium material on cell movement and osseointegration 21,22 have reported increases in surface concentrations of reactive species (O 2 ) and hydrophilicity that optimized cell growth. However, few studies 25,33 have looked at the effects of oxygen plasma treatment on bonding ability between titanium surfaces and luting cements.…”

“…19,20 NTP has been shown to achieve changes in surface chemistry without any cytotoxic effects. 19 Previous studies have investigated different NTP protocols, 21,22 mainly in order to assess cell response and gain a better understanding of the effects of altered implant surfaces on osseointegration. However, there is limited knowledge about the effect of shear forces on the luting cement applied on the titanium surfaces altered by NTP treatment.…”

Surface Modification of Direct-Current and Radio-Frequency Oxygen Plasma Treatments Enhance Cell Biocompatibility

“…For polymers, plasma bombards the polymer surface, increasing roughness [ 26 , 27 ]. Some relative studies proposed that plasma treatment might cause significant roughness changes on material surfaces, such as polished titanium, chitosan, or poly(etheretherketone) [ 4 , 28 , 29 ]. However, the plasma-treated SLA surface maintained its original surface texture, which contained micro- and sub-micro-scale roughness in all groups (as shown in Figure 1 and Figure 2 ).…”

“…Generally, hydrophilic surfaces exhibit better cell affinity, especially cell adhesion improvement [ 31 ]. A hydrophilic surface modification of titanium influenced differentiation and growth factor production for osteoblast-like cells [ 28 , 32 ]. Buser et al examined the commonly used hydrophilic SLActive implant, which promoted more bone healing in the early stage than the traditional SLA method [ 23 ].…”