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摘要
Introduction: The present study aimed to clarify the relationship between the amount of singlet oxygen (O-1(2)) generated from excited Methylene blue (MB) and the bactericidal effects on Enterococcus faecalis. Methods: A diode laser was used as the laser irradiation source (lambda = 660 nm, 200 mW). The laser irradiation time periods were 300, 600, and 900 seconds. In experiment 1, the amount of O-1(2) generated from each concentration (0.0001%-1.0%) of excited MB was examined by using electron spin resonance to determine the optimal concentration of MB. In experiment 2, the bactericidal effects of O-1(2) on E. faecalis were examined. Experimental groups were with laser irradiation, L(+); without laser irradiation, L(-); including MB, M(+); and not including MB, M(-). These were combined to form 4 groups: L(+)M(+), L(+)M(-), L(-)M(+), and L(-)M(-). After treatment, E. faecalis was incubated for 48 hours at 37 degrees C, and the bactericidal effects of O-1(2) on E. faecalis were determined on the basis of the number of colony-forming units per milliliter. Results: The largest amount of O-1(2) was generated from 0.01% excited MB. After 300, 600, and 900 seconds of irradiation, 35.2, 87.2, and 117.1 mu mol/L O-1(2) were detected, respectively. In groupL(+) M(+),colony-forming units per milliliter of E. faecalis dramatically decreased depending on the amount of O-1(2) generated. No other groups showed any bactericidal effects. Conclusions: Our findings suggest that 0.001%-0.01% of MB is the most effective range for generating O-1(2) during the application of antimicrobial photodynamic therapy. At least 35.2 mu mol/L generated O-1(2) was necessary to achieve the sterilization of E. faecalis. (1 Endod 2013;39:411-414)
- 出版日期2013-3
