In Vitro antimicrobial photoinactivation with methylene blue in different microorganisms

Abstract

Aim: To evaluate the in vitro antimicrobial effects of photodynamic therapy (PDT). Methods: The microorganism indicators were: Candida albicans, Pseudomonas aeruginosa,Enterococcus faecalis and Staphylococcus aureus. A microbial pool was prepared (10 8 cells/mL), from which aliquots were transferred to culture plates for carrying out the PDT using methylene blue (50 µM) and low-power laser (660 nm, 100 mW and 9 J).The effect of methylene blue alone, low power laser and the absence of treatments were evaluated. Then, aliquots of 1 µL were plated in a media culture, the number of colony forming units (CFU/mL) was obtained and the data submitted to the F test (ANOVA) with Tamhane's comparisons. Results:The laser radiation in the presence of methylene blue was able to eliminate 74.90% of C. albicans, 72.41% of P. aeruginosa, 96.44% of E. faecalis and 95.42% of S. aureus, thus statistically significant differences were found among the groups (p<0.001). Conclusions: PDT was effective in reducing the number of viable cells in the studiedmicroorganisms, especially E. faecalis and S. aureus.

The efficacy of photodynamic therapy and sodium hypochlorite in root canal disinfection by a single-file instrumentation technique

“…Due to their clinical importance and their role in endodontic failures [1,19], E. faecalis, P. aeruginosa, S. aureus and C. albicans were the microorganisms selected in this study because they presented resistance during antimicrobial therapy in agreement with Oliveira et al [9], Câmara et al [16] and Tirali et al [20].…”

“…Previous studies [9,31,37] have demonstrated that Gram-positive bacteria such as S. aureus and E. faecalis present higher susceptibility to the action of PDT compared to Gram-negative bacteria such as P. aeruginosa and fungi such as C. albicans. This occurs due to structural and compositional differences existing between those microorganisms, as Gram-positive bacteria possess an outer membrane that is relatively more porous than Gramnegative bacteria, allowing greater diffusion of the photosensitizer into the cell, whereas fungi possess a cell wall, which promotes a permeability barrier with a strength in between those of Gram-positive and Gram-negative bacteria [10].…”

“…With these conditions, multiples files and single-file instruments are similar [7,8]. In this regard, the use of Photodynamic Therapy (PDT) has emerged as a technological innovation auxiliary to endodontic treatment, seeking a more effective antimicrobial therapy [9][10][11][12].…”

The application of antimicrobial photodynamic therapy (aPDT) in dentistry: a critical review

“…Oliveira et al [48] evaluated, in vitro , the antimicrobial effect of aPDT using MB (50 μ M) and low level laser (660 nm, 100 mW and 9 J) against C. albicans , P. aeruginosa , E. faecalis and S. aureus . Laser radiation in the presence of MB eliminated 74.90% for C. albicans , 72.41% for P. aeruginosa , 96.44 and 95.42%, respectively for E. faecalis and S. aureus and showed statistically significant differences among the different groups ( p < 0.001).…”

Photodynamic Therapy: A Novel Ally for Surgical Endodontic Treatment? Case Report

“…Then, the retrograde cavity was prepared with an ultrasonic retro-tip (P1; Helse, Santa Rosa do Viterbo, SP, Brazil) (Figure 2a). After the conventional procedures, the retrograde cavity, as well as, the surgical cavity received an aqueous solution of 0.01% methylene blue (Chimiolux; Hypofarma, Belo Horizonte, MG, Brazil) for three minutes (Figure 2b), and, subsequently, were irradiated with a diode red laser (Whitening Lase II; DMC, São Carlos, SP, Brazil; diameter tip = 30 mm) for three minutes (wavelength = 660 nm, power = 100 mW, energy = 18 J, energy density = 640 J/ cm 2 , continuous emission mode) 8 (Figure 2c). After PDT, the surgical cavity was irrigated with a saline solution, the retrograde cavity was filled with a mineral trioxide aggregate (MTA Angelus; Londrina, PR, Brazil) ( Figure 2d), and the bone defect filled with calcium sulfate (Lumina-Set; Critéria, São Carlos, SP, Brazil) (Figure 2e).…”