Influence of ultrasonic activation on photodynamic therapy over root canal system infected with Enterococcus faecalis – an in vitro study

• We proposed the root canal decontamination through photodynamic therapy.
• We proposed a new modality of photodynamic therapy.
• We suggested an improvement of photodynamic therapy by ultrasonic activation.

SummaryAimThe purpose of this study was to evaluate, in vitro, the influence of ultrasonic activation on photodynamic therapy over root canal system infected with Enterococcus faecalis.Material and methodsThe root canals of 50 single-rooted human extracted teeth were enlarged up to a file 60, autoclaved, inoculated with Enterococcus faecalis and incubated for 30 days. The samples were divided into five groups (n = 10) according to the protocol of decontamination: G1 (control group) – no procedure was performed; G2 – photosensitizer (0.01% methylene blue); G3 – ultrasonic activation of photosensitizer (0.01% methylene blue); G4 – photodynamic therapy with no ultrasonic activation; and G5 – photodynamic therapy with ultrasonic activation. Microbiological tests (CFU counting) and scanning electron microscopy (SEM) were performed to evaluate and illustrate, respectively, the effectiveness of proposed treatments. Data were subjected to one-way ANOVA followed by post hoc Tukey test (α = 0.05).ResultsThe microbiological test demonstrated that G5 (photodynamic therapy with ultrasonic activation) showed the lowest mean contamination (3.17 log CFU/mL), which was statistically different from all other groups (p < 0.05). G4 (photodynamic therapy) showed a mean of contamination of 3.60 log CFU/mL, which was statistically different from groups 1, 2 and 3 (p < 0.05).ConclusionThe use of ultrasonic activation on photodynamic therapy improved its potential for decontamination, resulting in the higher elimination Enterococcus faecalis from the root canal space.