Anodic Oxidation Modification Improve Bioactivity and Biocompatibility of Titanium Implant Surface

Abstract

Current dental implant research aims at seeking an innovative surface able to promote a more favorable biological response to the cells and tissues at the bone-implant interface and to accelerate osseointegration. Anodic oxidation is a promising method for acquiring nanotube structures on the implant surface. In this paper, we modified the titanium surface using anodic oxidation to form nanotube structures on the surface and observed the surface by scanning electron microscopy (SEM). The bioactivity of the Ti implants was evaluated by simulated body fluid soaking test. We further sought to characterize the cellular and molecular responses of murine preosteoblast MC3T3-E1 cells to anodic oxidation modified titanium surface with a nanotube-texture. Gene expression of osteoprotegrin (OPG) was also evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and quantitative real-time PCR. SEM showed that the inner diameter of the nanotubes was about 70nm, the wall thickness was around 20nm, and the depth was about 200nm. The simulated body fluid soaking test displayed that bone-like apatite was formed on the nanotube-textured Ti surface after immersion in simulated body fluid for two weeks, but not on the smooth surface Ti surface. The biocompatibility was investigated by an in vitro cell culture test. Cell morphology exhibited a more differentiated characteristic, and gene expression of osteogenic markers OPG was also remarkably upregulated by anodic oxidation modification. Based on these results, it can be concluded that bioactivity and osteogenic responses to the nanotube-structured Ti surface were better than to the smooth surface, and gene expression indicates that OPG activation may be responsible for this increased osteogenic differentiation.