Surface Modification of SLA-treated Titanium Implant by Anodic Oxidation and CyclicPrecalcification Treatments

Abstract

This study was performed to evaluate the bioactivity of titanium implant modified by anodic oxidation and cyclic precalcification treatments. Twelve SLA-treated titanium implants with dimensions of 4.0 ㎜ in diameter and 11.5 ㎜ in length were used. In order to increase surface area, nanotubular TiO₂ layer were formed via anodic oxidation treatment. After that, the precalcification treatment which was carried out by alternative immersion in solution and Ca(OH)₂ saturated solution for 30 cycles was conducted to induce the precipitation of HAp crystals on the surface. Finally, the specimens were heat-treated for structural stability and elimination of remaining impurities. To investigate the bioactivity of these surface, the specimens were immersed in SBF solution and microstructural change of the surfaces was observed by FE-SEM. In addition, the concentration and the crystal structure of elements present on the surface were analyzed using an energy dispersive X-ray spectroscopy and X-ray diffraction, respectively. Nanotubes formed by anodizing treatment were completely self-arranged with dense structures in which the tubes with a small diameter were formed between the tubes with a relatively large diameter. Calcium phosphate precipitates were interlocked with the porous nanotubular surfaces and partially penetrated into the nanotubes after the cyclic precalcification treatments. Additionally, there was more precipitation of HAp as the result of immersion in the SBF for 5 days. The formation of nanotubular TiO₂ layers on titanium surface followed by HAp precipitation via cyclic precalcification treatments greatly improved bioactivity.