Corrosion of Titanium in Response to Sulfides From Porphyromonas gingivalis

Objectives: To determine the influence of sulfides produced by Porphyromonas gingivalis on the corrosion behavior of titanium.
Methods: Commercially available pure titanium disks 1.3 mm thick and 13.0 mm in diameter were prepared and mirror polished according to metallographic procedures (MP). Titanium disks were immersed in culture medium (BHI), spent culture medium after culturing Porphyromonas gingivalis (P. gingivalis) (BHI-S), and culture medium with P. gingivalis (BHI-P) and corrosion behavior was investigated. Specimens were placed in 3mL of test mediums and incubated aerobically at 37°C for 3 to 14 days for a total of 14 days. BHI-S and BHI-P mediums were renewed every 7 and 3-4 days respectively. Bacterial growth was confirmed through surface observation (FE-SEM) and sulfide levels. Titanium corrosion was evaluated through changes in color (ΔE*ab) and glossiness (Gs(20°)), and chemical composition using X-ray Photoelectron Spectroscopy (XPS). Trypsin was used to remove surface protein from the specimens before evaluation.
Results: ΔE*ab and ΔG(20°) did not significantly differ among the specimens placed in test mediums for 1 and 2 weeks (p>0.05). SEM images showed no signs of localized or overall corrosion on the specimens. XPS analysis showed sulfide and sulfate peaks on BHI-S and BHI-P confirming its attachment. All specimens showed clear titanium peaks regardless of the mediums’ sulfide content or presence of P. gingivalis. Valency fraction of titanium decomposed from Ti2p spectrum of BHI-S and BHI-P indicated no progression of oxidation in comparison to MP and BHI.
Conclusions: Within the limitations of this study, sulfides produced by P. gingivalis were detected on the surface of titanium specimens however oxidation was not indicated over the duration of 14 days.