Nanoparticle-based Endodontic Antimicrobial Photodynamic Therapy

Objective: To study the in vitro effects of poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with the photosensitizer methylene blue (MB) and light against Enterococcus faecalis (ATCC 29212). Materials and Methods: The uptake and distribution of nanoparticles in E. faecalis in suspension was investigated by transmission electron microscopy (TEM) after incubation with PLGA complexed with colloidal gold particles for 2.5, 5, and 10 minutes. E. faecalis species were sensitized in planktonic phase and in experimentally infected root canals of human extracted teeth with MB-loaded nanoparticles for 10 minutes followed by exposure to red light at 665 nm. Results: The nanoparticles were found to be concentrated mainly on the cell walls of microorganisms at all three time points. The synergism of light and MB-loaded nanoparticles led to approximately 2 and 1 log(10) reduction of colony-forming units (CFUs) in planktonic phase and root canals, respectively. In both cases, mean log(10) CFU levels were significantly lower than controls and MB-loaded nanoparticles without light. Conclusion: The utilization of PLGA nanoparticles encapsulated with photoactive drugs may be a promising adjunct in antimicrobial endodontic treatment. (J Endod 2010;36:322-328)