An antibacterial surface on dental implants, based on the photocatalytic bactericidal effect

Background: It is well known that the moderately roughened surfaces of dental implants enhance direct bone-implant contact. However, rough implant surfaces, as compared to smooth surfaces, are thought to pose a higher risk of bacterial infection when exposed to the oral cavity. Purpose: This study was focused on evaluating the photocatalytic bactericidal effects of anatase titanium dioxide (TiO₂) on gram-negative anaerobic bacteria known to be associated with periimplantitis. Materials and Methods: A film of photocatalytic anatase TiO₂ was added onto the surface of commercially pure titanium disks by plasma source ion implantation (PSII) followed by annealing. The photocatalytic properties of the film were confirmed by the degradation of methylene blue. Actinobacillus actinomycetemcomitans and Fusobacterium nucleatum cells were incubated anaerobically and seeded on the disk. The disks were then exposed to ultraviolet A (UVA) illumination from black light in an anaerobic environment. After illumination, the number of viable cells was counted in terms of colony-forming units. Results: The anatase TiO₂ film added by the PSII method and annealing exhibited a strong photocatalytic reaction under UVA illumination. The viability of both types of bacteria on the photocatalytic TiO₂ film was suppressed to less than 1% under UVA illumination within 120 minutes. Conclusion: The bactericidal effect of the TiO₂ photocatalyst is of great use for sterilizing the contaminated surface of dental implants.