Objectives: Antimicrobial photodynamic therapy (aPDT) in periodontal pockets using lasers is difficult to perform in some cases because of the high cost of irradiation equipment and the narrow irradiation field. The purpose of the present study was to examine the effects of aPDT in combination with a plaque-disclosing solution and blue light-emitting diode (LED), which are used for composite resin polymerization.
Methods: The reactive oxygen species generated by irradiating 0.001% RB or MB with blue light were analyzed using electron spin resonance spectroscopy. Blue-light exposure was performed at 6.92, 20.76 and 124.6 J. The microorganism to be sterilized was Porphyromonas gingivalis. After aPDT, colony-forming units (CFUs) were measured to estimate cell survival. Carbonylated protein (PC) levels were used to evaluate oxidative stress. All statistical analyses were performed with Tukey's multiple comparisons test or the unpaired t-test.
Results: Singlet oxygen (1O2) generation was confirmed by RB+blue LED. 1O2 production was significantly greater with the blue LED irradiation of RB than that of MB (p < 0.0001). CFUs were significantly lower in the blue LED-irradiated group than in the non-LED-irradiated group (p < 0.01). The bactericidal effect increased in a time-dependent manner. aPDT increased PC levels. No morphological changes were observed in P. gingivalis.
Conclusions: The present results suggest that aPDT exerts bactericidal effects against P. gingivalis by increasing oxidative stress through the generation of 1O2 in cells. Periodontal disease may be treated by aPDT using the equipment available in dental offices.
Keywords: Antimicrobial photodynamic therapy; Blue light; Oxidative stress; Plaque disclosing solution; Porphyromonas gingivalis; Reactive oxygen species.
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