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

Abstract Introduction: 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.Methods: Bacterial suspensions (۲۰۰ μL) of P. gingivalis were exposed to either TBO with concentration of ۰.۱ mg/mL associated with portable light-emitting diode (LED) device (peak wavelength: ۶۳۰ nm, output intensity: ۲.۰۰۰ mW/cm۲, tip diameter: ۶.۲ mm) or ۰.۱% Radachlorin® and laser irradiation (InGaAlP, Peak wavelength: ۶۶۲±۰.۱% nm, output power: ۲.۵ W, energy density: ۶ J/cm۲, fiber diameter: ۲ 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.Results: LED-based aPDT reduced the colony count of P. gingivalis more than that of TBO (P < ۰.۰۰۱) or LED group (P = ۰.۹۵۷). Also, laser-based aPDT had a great reduction in colony count of P. gingivalis in comparison with Radachlorin® (P < ۰.۰۰۱) or laser irradiation alone (P = ۰.۲۸). In addition, the colony count reduction of laser-based aPDT was significantly more than LED-based aPDT (P < ۰.۰۵).Conclusion: Considering the results of this study, the viability of P. gingivalis was more affected by the combination of laser and Radachlorin® ۰.۱% in comparison with LED and TBO ۰.۱% Keywords: Photochemotherapy Photosensitizing agents Porphyromonas gingivalis Lasers Periodontics.