The aim of this study was to evaluate the effects of plasma treatment on adhesion between fiber-reinforced posts and a composite core material. Two types of posts, methacrylate-based (FRC Postec) and epoxy resin-based (DT Light-Post), were treated with oxygen plasma (O2), argon plasma (Ar), nitrogen plasma (N2), or helium mixed with nitrogen plasma (He+N2) using a radio-frequency generator before bonding to a methacrylate-based composite. Pull-out tests were performed using a universal testing machine. Surface roughness of each group was evaluated using a profilometer. On tensile-shear bond strength, statistical analysis revealed that the type of post, type of plasma treatment, and their interaction significantly influenced the results (p<0.05). Tukey's test revealed significant differences in tensile-shear bond strength between the control and other plasma treatment groups (p<0.05). On surface roughness, Tukey's test revealed significant differences between the control group and the Ar group (p<0.05) with DT Light Post. Plasma treatment appeared to increase the tensile-shear bond strength between post and composite.

No abstract

Polyetheretherketone (PEEK) has become an alternative material for orthopaedics and dental implants. However, bio-inertness is an important limitation in this material. In the present study, a hydroxyapatite (HA)–titanium nitride (TiN) coating was fabricated via pulsed DC magnetron sputtering and treated with hydrothermal treatment to improve the bioactive property of PEEK. The dissolution behavior of the coating was studied in simulated body fluid solution (SBF) at 1, 3, 5, 7, 14, 21, 28, and 56 days. The coating surface was analyzed before and after the immersion process by X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and scanning electron microscope (SEM). The calcium and phosphorus concentration alteration in SBF was quantified by an inductively coupled plasma-optical emission spectrometer (ICP-OES). Coating dissolution and the precipitation of calcium phosphate complex from SBF were observed as occurring suddenly and continuously throughout the immersion times. These processes resulted in an alteration in both physical and chemical coating properties. After 56 days, the coating remained on PEEK surfaces and the Ca/P ratio was 1.16. These results indicate that HA-TiN coating via pulsed DC magnetron sputtering followed by hydrothermal treatment improved the bioactivity of materials and provided a potential benefit to orthopedics and dental applications.

No abstract

This study sought to investigate the effect of immersion time in simulated body fluid (SBF) on the adhesion strength of hydrothermally treated hydroxyapatite-titanium nitride (HA-TiN) films on polyetheretherketone (PEEK) substrates. The HA-TiN films were deposited on PEEK substrates via magnetron sputtering and annealed with hydrothermal treatment. The crystalline phase and element compositions on the deposited films were confirmed by X-ray diffractometry (XRD), and X-ray photoelectron spectrometry (XPS). The samples were then immersed in SBF at 37°C for 7 to 56 days, where the surface characterization and chemical composition of the films were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), and XPS. After the in vitro degradation in SBF, the adhesion strength between HA-TiN films and PEEK substrates were measured by a universal testing machine and further investigated the failure mode using a stereomicroscope and SEM. The results demonstrated the improvement of crystallinity on HA-TiN sputtered films after hydrothermal treatment. After immersion in SBF, the coating surface revealed some nucleation without any detachment and exhibited an increase of surface roughness. The hydroxyapatite and titanium dioxide were revealed on the surface throughout the 56 days, while the Ca/P ratio decreased and remained constant during immersion. The adhesion strength did not significantly differ in all groups. These findings concluded that hydrothermally treated HA-TiN sputtered films on PEEK substrates showed the stability of adhesion strength throughout 56 days in simulated physiological conditions. The dissolution and precipitation during immersion represented the favorable characteristics of the films in the orthopedic or dental application. Keywords: Adhesion, Degradation, Thin films, Hydroxyapatite, Titanium dioxide