Antimicrobial effect of photodynamic therapy using high‐power blue light‐emitting diode and red‐dye agent on Porphyromonas gingivalis. (27th February 2013) - Chui, C.
Abstract : Background and Objective: Antimicrobial photodynamic therapy (a‐PDT) using a combination of red‐colored laser/light‐emitting diode (LED) and blue dye has been employed for periodontal therapy and the antimicrobial effect seems promising. Blue light, which has favorable wavelength properties, would be more effective as a light source for a‐PDT because blue light itself possesses an antimicrobial effect. This study aimed to investigate the effect of a‐PDT using a novel combination of high‐power blue LED and red‐dye agent on Porphyromonas gingivalis in vitro . Material and Methods: Porphyromonas gingivalis ATCC 33277 suspension was irradiated with blue LED (BL) (425–470 nm) or red LED (RL) (625–635 nm) at 30–90 J/cm 2, or was mixed with erythrosine (ER), phloxine B (PB) or rose bengal (RB) with or without BL irradiation (30 J/cm 2 ). RL (30 J/cm 2 ) in combination with toluidine blue was employed as positive control. All the suspensions of P. gingivalis were serially diluted, plated and incubated anaerobically, and the numbers of colony‐forming units (CFUs) were counted on day 7. Results: BL irradiation at 60 and 90 J/cm 2 demonstrated a significant reduction in the numbers of CFUs. ER, PB and RB solutions at 160 μg/mL showed almost no or only a minimal reduction in the numbers of CFUs. BL at 30 J/cm 2 combined with ER, PB or RB at 160 μg/mL resulted in a log reduction of 0.9, 1.0 and 7.1, respectively, in the numbers of CFUs; 30 J/cm 2 BL with RB at 1.6, 16 and 160 μg/mL demonstrated a log reduction of 6.3, 8.0 and 5.5, respectively; and a log reduction of 5.2 was obtained after 30 J/cm 2 RL with 16 μg/mL TB. Conclusion: Within the limits of this study, BL was found to have an antimicrobial/growth‐inhibiting effect on P. gingivalis, and a‐PDT using a combination of BL and RB shows promise as a new technical modality for bacterial elimination in periodontal therapy.