Objective:To study the effects of Porphyromonas gingivalis colonization on titanium surface oxide film properties. Methods:The samples of pure titanium were immersed in Porphyromonas gingivalis bacterial suspensions. Biofilm microstructure on the titanium surface was observed using scanning electron microscopy(SEM). The experimental groups were immersed in bacterial suspensions while the control group was immersed in physiological saline. After being co-cultured for 7,14,and 21 days,both samples and solutions were collected to analysis titanium surface properties using X-ray photoelectron spectroscopy(XPS) and to detect the quantity of titanium ion release using inductively coupled plasma optical emission spectrometer(ICP-OES),respectively. Results:SEM observed a dense biofilm after Porphyromonas gingivalis colonized on the titanium surface. With co-culture time increased,the XPS survey spectra showed reductions in the surface levels of titanium and oxygen,corresponding with an evident reduction of dominant titanium dioxide (TiO2) on the titanium surface revealed by the XPS high resolution spectra. ICP-OES indicated a increase of titanium ion release after colonization of Porphyromonas gingivalis on the titanium surface with the time extension,and the fastest release rate happened in the first week. Conclusion:Porphyromonas gingivalis was able to colonize on the titanium surface and form a dense biofilm. Porphyromonas gingivalis colonization weakened the protective TiO2 film on the titanium surface and induced the release of titanium ions,which enhanced with the bacterial action time prolonged.