Photodynamic Inactivation of Porphyromonas gingivalis utilizing Radachlorin and Toluidine Blue O as Photosensitizers: An In Vitro Study

Porphyromonas gingivalis is one of the major pathogens in the development and progression of periodontal disease. Antimicrobial photodynamic therapy (aPDT) is a new approach which is sorted in non-invasive phototherapy for bacterial elimination. This in vitro study was conducted to compare photodynamic inactivation using Radachlorin and Toluidine blue O (TBO) as photosensitizers on P. gingivalis.
Bacterial suspensions (200 μL) of P. gingivalis were exposed to either TBO with concentration of 0.1 mg/mL associated with portable light-emitting diode (LED) device (peak wavelength: 630 nm, output intensity: 2.000 mW/cm2, tip diameter: 6.2 mm) or 0.1% Radachlorin® and laser irradiation (InGaAlP, Peak wavelength: 662±0.1% nm, output power: 2.5 W, energy density: 6 J/cm2, fiber diameter: 2 mm). Those in control groups were subjected to laser irradiation or LED alone, Radachlorin® or TBO alone, and one group received neither photosensitizer nor light irradiation. Then counting of colony forming units (CFU) was performed to determine the bactericidal effects in each subgroup.
LED-based aPDT reduced the colony count of P. gingivalis more than that of TBO (P Considering the results of this study, the viability of P. gingivalis was more affected by the combination of laser and Radachlorin® 0.1% in comparison with LED and TBO 0.1%.