Attachment of Porphyromonas gingivalis To Corroded Titanium Discs

Dental Implant surfaces, made of titanium, can get corroded due to electrochemical interaction in the oral environment. The corrosion process may result in surface modification either chemically or topographically. We hypothesized that modified titanium (Ti) surface due to corrosion process may enhance attachment of periodontal pathogens. Objectives: To evaluate the effect of corroded Ti surfaces on attachment of Porphyromonas gingivalis  (Pg). Methods: The Ti discs used in this study included cp-Ti (type 2) and Ti-6Al-4V (type 5). Ti discs alloy were anodically polarized in a standard 3-electrode setting in simulated oral environment in artificial saliva at pH 3, 6.5 and 9. Non-corroded discs were used as control. A total of 24 discs (three for each pH and three for controls) were used. Test discs were placed in 12-well microtiter plates containing growth medium, inoculated with Pg, and incubated at 37 ^oC. After 4 hr, the discs with attached Pg were washed gently with phosphate buffer (0.05M, pH 6.5) and stained with crystal violet and attachment was expressed based on O.D. at 550nm. The attached cells were also stained with LIVE/DEAD BacLight ^TM, and the biofilm examined under a fluorescent Leica DMRE microscope (Wetzlar, Germany). Results: Both type 2 and type 5 corroded discs at all pHs promoted significantly more bacterial attachment than the non-corroded controls (11.02% and 41.78%; p<0.0001). Significantly higher amount (11.8%) of Pg attached to the Type 2 discs than the type 5 discs (p<0.074). In both type 2 and type 5 Ti discs, significantly higher bacterial attachment was noted in group pH 3 and pH 9 discs compared to the group pH 6.5 (type 2, p<0.014; type 5, p<0.0001). Conclusion: Based on data obtained from the current study, higher degree of implant surface corrosion may facilitate bacterial attachment and potentially leading to implant failure.