Objective:To evaluate the effects of micro-nano patterned titanium surface modification on Streptococcus mutans adhesion. Methods:According to different titanium surface modifications,there were four groups:Mechanical polishing group,Sandblasting group,Anodic oxidation group,and Sandblasting-anodic oxidation group. The specimen of each group were characterized by scanning electron microscopy. The contact angles of double distilled water on specimen of each group were calculated to evaluate the wettabilities. The specimens were incubated in Streptococcus mutans cell suspension,and the bacteria on specimens were numbered by colony-forming units and observed by scanning electron microscopy. Results:Scanning electron microscope demonstrated that the micro-nano patterned structure of nano-tube arrays within micro-pores grew on the titanium surface of Sandblasting-anodic oxidation group. The sequence of surface contact angles among four groups was as follows:Mechanical polishing group,Sandblasting group > Anodic oxidation group,Sandblasting-anodic oxidation group. The sequence of the bacterial adhesion quantities among four groups was as follows:Anodic oxidation group,Sandblasting-anodic oxidation group > Sandblasting group > Mechanical polishing group. Conclusion:In comparison with the nano-tube arrays,the micro-nano patterned surface modification did not increase the adhesion of Streptococcus mutans on the titanium surface.