Effect of photodynamic therapy according to differences in photosensitizers on Staphylococcus aureus biofilm on titanium.

PURPOSE

This study aimed to evaluate the antimicrobial effect of photodynamic therapy (PDT) against Staphylococcus aureus biofilm on a titanium surface and to compare the differences in the effect of PDT using toluidine blue O (TBO) and methylene blue (MB) as a photosensitizer.

METHODS

The bacterial strain S. aureus ATCC 25,923 was used. Sandblasted and acid-etched (SLA) disks were divided into the following six groups: phosphate buffer saline (PBS), TBO, MB, PBS with laser (PBS + L), TBO with laser (TBO + L), and MB with laser (MB + L). The laser group samples were irradiated by a cold diode laser for 60 s. After treatment, the number of surviving bacteria was calculated by counting the colony-forming units (CFUs) and confocal laser scanning microscopy (CLSM) was applied to observe the bacteria on the disk surface.

RESULTS

The TBO + L and MB + L groups showed significantly lower CFU/ml than the other groups (p < 0.01). The TBO + L group showed significantly lower CFU/ml than the MB + L group (p = 0.032). There was no significant difference between the PBS, TBO, MB, and PBS + L groups. Within the limitations of this in vitro study, PDT with TBO and MB can effectively reduce S. aureus biofilm on SLA titanium surfaces. TBO is more effective than MB as a photosensitizer. PDT with TBO may be applied to the treatment of peri‑implant disease in the future.