Experimental Study On The Effect Of Porphyromonas Gingivalis Synergistically With Titanium Corrosion Behavior On Osteoblasts

Part I Effects of Porphyromonas gingivalis colonization on titanium surface oxide film propertiesObjective 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、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 significant 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.Conclusions 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 prolongedPart Ⅱ Synergistic effects of Porphyromonasgingialis-lipopolysaccharide and titanium ions on the behavior of MC3T3-E1 cellsObjective To study the influences of Porphyromonas gingivalis-lipopolysaccharide(Pg-LPS)and titanium ions(Ti ions)on MC3T3-E1 cells.Methods The proliferation of MC3T3-E1 cells were evaluated in the context of different concentrations of Pg-LPS and Ti ions exposure.Afterwards,the effects of Ti ions(5 ppm)on the proliferation and adhesion of MC3T3-E1 cells stiumlated with Pg-LPS(10 μg/mL)was analysed.The genes expression levels of OSX、COL1、CCL2 and TLR4 of MC3T3-E1 cells being exposed to Pg-LPS and Ti ions for 24 h were measured using real-time quantitative PCR.Results Pg-LPS at the concentration range 1-10 μg/mL had no significant effects on the cell viabilities of MC3T3-E1 cells,and a significantly reduced of cell proliferation could only be observed after being exposed to 100 μg/mL Pg-LPS for 5 days.Ti ions at the concentration of 10 ppm significantly decreased the viabilities of MC3T3-E1 cells in 1、3 and 5 days,while 5 ppm Ti ions inhibited cell proliferation in 3 and 5 days.The addition of 10 μg/mL Pg-LPS had no significant changes in the viabilities of MC3T3-E1 cells loaded with 5ppm Ti ions.MC3T3-E1cells showed more poor cell spreading and less attached cell numbers after simultaneously exposed to Pg-LPS and Ti ions.The results of real-time quantitative PCR showed that Pg-LPS and Ti ions had synergistic effects on MC3T3-E1 cells,including decrease in the mRNA expression of OSX、COL1 and increase in the mRNA expression of CCL2 and TLR4.Conclusions Pg-LPS had no significant effects on the viabilities of MC3T3-E1cells,while a significantly reduced of cell proliferation could be observed after being exposed to Ti ions.Pg-LPS and Ti ions negatively affected the adhesion of MC3T3-E1 cells on titanium surface.Ti ions increased the sensitivity of osteoblasts to Pg-LPS.Pg-LPS and Ti ions synergistically stimulated the inflammatory response and inhibited the osteoblast differentiation,which may contribute to bone resorption.