Fabrication of rough surface on titanium using electrochemical treatment in NaCl electrolyte / 대한치과재료학회지

It is difficult to get sufficient roughness on titanium implant surface using traditional electrochemical treatments. In this study, we have developed a new method which provides a hybrid structured titanium surface having micro/nano roughness using electrochemical treatment in NaCl electrolyte and hydrothermal treatment. Titanium disks were anodically oxidized (ANO) in 0.15M NaCl electrolyte by applying positive electric pulses. The oxide compounds loosely attached to the surface were removed by ultrasonic cleaning (ANO group). These specimens were hydrothermally (HT) treated in an alkaline solution (ANO-HT group). ANO group showed the dimpled grain surfaces with a diameter of approximately 30 µm, and its roughness (Ra) was about 2.4 µm. The nano-sized crystallites which had an anatase TiO₂ crystalline structure were uniformly distributed on the surface of ANO-HT group. This group still retained high roughness (~2.7 µm) similar to ANO group and showed high hydrophilicity. Titanium surface with high roughness and hydrophilicity was fabricated using new electrochemical treating method and hydrothermal treatment. This surface modification method could be used for enhancing the osteoconductivity of the titanium implants.

Surface characterization of calcium phosphate coating formed on chitosan and alkali-treaDted titanium metal / 대한치과재료학회지

The calcium phosphate coating on various pretreated metals was prepared by soaking in modified simulated body fluid (m-SBF) solution. The coating structure and its surface morphologies were determined by x-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results revealed significant differences in morphology and composition of the calcium phosphate coatings with and without chitosan and NaOH-pretreated commercially pure titanium (cp-Ti) substrate. The calcium phosphates formed on chitosan coated-Ti pretreated with NaOH were ~ 350 nm-sized resulting in strong bonding of the apatite layer with the substrates and a uniform gradient of stress transfer from coating materials to the Ti-substrate. After NaOH pretreatment, the hydroxyl groups bind to Ca²⁺ to attract PO₄³⁻ anions, eventually resulting in a continuous layer of calcium phosphate on chitosan coated-Ti substrate during immersion in m-SBF solution. The chitosan coated-Ti showed hydrophobic surface while NaOH pretreatment resulted in maximum hydrophilicity to the Ti substrate. Due to improved wettability of Ti by NaOH pretreatment before chitosan coating, aggregation of calcium phosphate was prevented and size-controlled composite materials were obtained.

Hydroxyapatite Coatings on Titanium Using Electrochemical Deposition Method at Body Fluid Temperature / 대한치과재료학회지

In this study, hydroxyapatite (HAp) was coated on titanium using electrochemical deposition (ECD) method at body fluid temperature. The titanium specimens for ECD were prepared by chemically etching treatment using 5M NaOH solution. The electrolyte mixed with 5 mM Ca(NO³)² and 2 mM NH⁴H²PO⁴ which has pH 5 (E2) was adjusted to pH 3 (E1) and pH 6 (E3). The different electric pulses of −10, −15, −30 mA were applied to each specimen. The temperature of electrolytes was kept at 37℃. E1-10, E1-15, E1-30, E2-10, E2-15, E2-30, E3-10, E3-15, and E3-30 groups were prepared for this study. Scanning electron microscope (SEM) images showed that E1-10 and E1-15 groups were not coated and the powder-shaped compounds were formed on E3-15 and E3-30 groups. The cracks were observed on the surface of E1-30 and E2-30 groups. The evenly and stable coated layer was deposited on E2-10, E2-15 and E3-10 groups. The layer coated on titanium surface had an HAp crystalline structure. E1-30 and E2-30 groups had low crystallinity, even though they had thick layer. HAp layer on for E2-10 group was well deposited on the surface because it more aligned to c-axis compared with other groups.