Evaluation of Antimicrobial Photodynamic Therapy Using Indocyanine Green and Near-Infrared Diode Laser Against Enterococcus faecalis in Infected Human Root Canals.

OBJECTIVE

Photodynamic therapy (PDT) is considered a promising adjunct to the currently available endodontic disinfection techniques leading to more effective reduction of intracanal bacteria. The present ex vivo study aimed to assess the antimicrobial effect of PDT using indocyanine green (ICG) as photosensitizer and a near-infrared (NIR) diode laser in root canals of human teeth infected with Enterococcus faecalis.

MATERIALS AND METHODS

Ninety single-rooted teeth after chemomechanical preparation and sterilization were contaminated with an E. faecalis strain. The specimens were divided, randomly, into eight experimental groups: (1) PDT with ICG and laser (0.5 W output power-medium-energy fluence), (2) PDT with ICG and laser (1 W output power-high-energy fluence), (3) only laser emission, (4) only ICG, (5) 2.5% sodium hypochlorite (NaOCl) as irrigant, (6) 2.5% NaOCl and PDT with ICG and laser, (7) no treatment (positive control), and (8) no bacterial biofilm growth (negative control). The root canal contents were sampled by flushing and the collected washings were plated on an appropriate culture medium, which was incubated for 48 h at 35°C ± 2.0. The colony-forming units (CFUs) were determined to assess the bactericidal effect of the tested experimental combinations.

RESULTS

The microbiological tests revealed that PDT groups, regardless of the overall power, showed significant lower mean log CFU levels, than groups 3 and 4 (p < 0.001) and similar reduction of viable counts with group 5. The combination treatment (group 6) achieved adequate reduction of log CFU levels in the viable counts. However, no significant difference (p > 0.05) was observed between groups 1, 2, 5, and 6 and significant difference was noticed between groups 3, 4, and 5 (p < 0.001).

CONCLUSIONS

ICG-mediated PDT activated by an NIR diode laser provided increased disinfection of the root canal system, but the overall benefit in total bacterial elimination should be further investigated.