A study on bacterial attachment on titanium and hydroxyapatite based films

The attachment of the oral bacteria Porphyromonas gingivalis on titanium (Ti), titanium nitride (TiN) and modified hydroxyapatite (HA) films was studied. Direct current magnetron sputtering method was used to deposit various Ti and TiN films with similar smooth topography but different surface composition as investigated by using atomic force microscope and X-ray photoelectron spectroscope. Native oxidation was predominant in all the films, however, the nitrogen percentage varied from 2.6–14.1% and 3.1–19.3% in the surface of Ti and TiN films respectively. Fluorine and zinc modified HA films were prepared by solution gel method. Replacement of a percentage of OH− group by F and 3.2 at.% of Ca by Zn in hydroxyapatite was confirmed by Fourier transform infrared spectroscope and energy dispersive analysis using X-rays measurements respectively. All the film samples were sterilized by gamma radiation or pressurized steam prior to bacterial culture experiments. The bacterial culture was performed at anaerobic condition and the bacteria treated samples were examined by means of scanning electron microscope measurements. A few of the Ti films with typical surface stoichiometries of combinations of oxygen and nitrogen exhibited minimum bacterial attachment, and on the modified HA films relatively less attached bacteria were recorded. The TiN films did not show any inhibiting action against the attachment of the bacteria, where more number of bacteria were found attached on the TiN films independent of the surface chemical composition of the films.