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Photodynamic inactivation of Enterococcus faecalis in dental root canals in vitro
Author(s) -
Foschi Federico,
Fontana Carla R.,
Ruggiero Karriann,
Riahi Reza,
Vera Antonio,
Doukas Apostolos G.,
Pagonis Tom C.,
Kent Ralph,
Stashenko Philip P.,
Soukos Nikolaos S.
Publication year - 2007
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.20579
Subject(s) - enterococcus faecalis , root canal , photodynamic therapy , agar plate , methylene blue , scanning electron microscope , chemistry , agar , bacteria , microbiology and biotechnology , chromatography , dentistry , materials science , biology , medicine , staphylococcus aureus , biochemistry , organic chemistry , photocatalysis , composite material , genetics , catalysis
Background and Objectives We previously reported the use of a flexible fiber optic that uniformly distributed light in the root canal space for targeting bacteria after their sensitization with methylene blue (MB). In the present study, we investigated the photodynamic effects of MB on Enterococcus faecalis species in experimentally infected root canals of extracted teeth after their sensitization with a concentration of MB that exhibits reduced dark toxicity. Study Design/Materials and Methods In a model of root canal infection, 64 root canal specimens were prepared from extracted, single‐rooted teeth and inoculated with E. faecalis (ATCC 29212). Three days later root canal infection was confirmed by scanning electron microscopy. The root canal systems were then incubated with 6.25 µg/ml MB for 5 minutes followed by exposure to light at 665 nm (60 J/cm 2 ) that was delivered from a diode laser via a fiber optic with a diameter of 500 µm. Following photodynamic therapy (PDT) the canal content was sampled by flushing the root canals, serially diluted and cultured on blood agar. Survival fractions were calculated by counting colony‐forming units. High‐performance liquid chromatography (HPLC) was employed to determine the porphyrins content of E. faecalis . Results Scanning electron microscopy confirmed the presence of bacteria in the root canal system. PDT achieved 77.5% reduction of E. faecalis viability. MB alone and light alone reduced bacterial viability by 19.5% and 40.5%, respectively. HPLC did not reveal any porphyrin patterns expressed by E. faecalis . Conclusion The results of this study support the need to determine the optimum MB concentration and light parameters to maximize bacterial killing in root canals. Lasers Surg. Med. 39:782–787, 2007. © 2007 Wiley‐Liss, Inc.