치과 임플란트 Ti합금에 Ca 및 P가 함침된 PEO피막에서 나노튜브형성

Abstract

The dental implant was required excellent corrosion resistance, biocompatibility, osseointegration, and excellent mechanical properties. In general, Cp-Ti and Ti–6Al–4V alloy were mainly used for dental materials. Cp-Ti and its alloys can be connected to the bone, but it is difficult to have chemically strong bonds. For this reason, various surface treatment methods for improving bioactivity have been actively studied. In this study, nanotube formation on dental implant surface after Ca and P doping by PEO treatment were investigated with the condition of various PEO treated time (1, 3, 5, and 10 min). And then, formed the nanotube films on the PEO-treated films were investigated with the initial PEO treatment duration.

The substrate used in this study was Ti-6Al-4V ELI disk (Grade 5, ZAPP, Germany). Samples were used as anodes and high dense carbon rod was used as cathode. Electrolytes were for PEO (plasma electrolytic oxidation) process as follows: 0.15M calcium acetate monohydrate and 0.02M calcium glycerophosphate at 280V for various duration (1, 3, 5, and 10 min) using DC power supply (6812B. KEYSIGHT Co., USA). And then, these samples were used as anodes and platinum rod was used as cathode. The nanotube oxide films were formed on the PEO films by an anodic oxidation method in 1M phosphoric acid electrolyte containing 0.8 wt.% sodium fluoride at 30V for 1 hour. Surface morphology and content of elements were investigated by field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS). The phase and crystallite size were observed by X-ray diffraction (XRD). Surface characterization were examined by wettability, roughness, and Vicker's hardness test.

The results were as follows:

1. The PEO-treated surface with containing Ca and P ion was formed porous oxide layer by PEO method and size of pores were distributed 0.6-5.8 ㎛. As PEO-treated time increased, porosity and number of pore decreased, and maximum and minimum size of pore increased.

2. In case of PEO+Nanotube treated sample, nanotube was formed by anodic oxidation method on the PEO films. The diameter of nanotube was 44-96 nm, as initial PEO treatment time increased, the diameter of nanotube increased, and the wall thickness decreased.

3. From the EDS analysis, as PEO treatment time increased, the content of Ca and P ions increased, and Ca/P ratio was higher on the surface.

4. In case of PEO-Nanotube treated sample, as the initial PEO treatment time increased, the content ion (Ca, P) and Ca/P ratio increased. It was higher the pore than surface. But, PEO+Nanotube treated samples had a lower content and Ca/P ratio than PEO-treated sample.

5. The XRD pattern of anatase phase was observed on PEO and PEO+Nanotube films. As PEO-treated time increased, the crystallite size of anatase was slightly larger and it was larger with PEO-treated samples.

6. The result of wettabiliy test, it was affected by PEO treatment time, surface roughness and pore properties. As PEO-treated time increased, contact angle increased on PEO-treated sample. Regardless of initial PEO treatment time, the sample of PEO+Nanotube had a superior wettability.

7. The surface roughness (Ra) and the Vicker's hardness were depended on the initial PEO treatment time, its values were increased with PEO-treated time from 1 min to 10 min. The sample of PEO+Nanotube was higher surface roughness, but, the Vicker's hardness was higher PEO-treated sample.