Indocyanine green‑activated photodynamic therapy with diode laser eradicates Enterococcus faecalis in infected root canals: An in vitro study

Abstract

Background: The current endodontic disinfection techniques may be supplemented with
photodynamic therapy (PDT), which is believed to eliminate intracanal bacteria more efficiently. This
in vitro study aimed to assess the antimicrobial effectiveness of PDT using various photosensitizers,
in conjunction with a near‑infrared diode laser (810 nm wavelength), in the root canals of teeth
infected with Enterococcus faecalis. This research is crucial for determining the optimal PDT method
for eliminating E. faecalis, thereby enhancing the effectiveness of endodontic disinfection techniques.
Materials and Methods: This in vitro experimental study was conducted on 50 intact human
maxillary first molars, which were decoronated, and palatal roots were instrumented to ISO size
X5. After autoclaving, roots were inoculated with E. faecalis (ATCC 29212; 108 CFU/mL) and
incubated anaerobically for 72 h. The roots were randomly divided into five experimental groups:
control (C), laser alone (L), PDT with indocyanine green (ICG), PDT with methylene blue (MB),
and PDT with cetrimide (CT) 2%. Root canals were flushed with phosphate‑buffered saline, and
serial dilutions were plated on agar. Colony‑forming units were counted after 48‑h incubation. Data
were analyzed using one‑way analysis of variance followed by Tukey’s post hoc test for pairwise
comparisons. A significance level of P < 0.05 was considered.
Results: PDT with ICG resulted in complete eradication of E. faecalis (0 CFU/mL), whereas
PDT with MB and CT produced significant reductions (5.08 ± 0.2 and 5.55 ± 0.1 log10 CFU/mL,
respectively; P < 0.05). Laser alone reduced CFU/mL to 5.94 ± 0.07.
Conclusion: PDT with ICG and an 810 nm diode laser achieved complete eradication of E. faecalis,
outperforming MB, CT, and laser alone. These results advocate for ICG‑PDT as a potent adjunct
in endodontic disinfection protocols.
Key Words: Anti‑infective agents, diode laser, drug combination, endodontics, photodynamic therapies, photosensitizing agents, root canal preparation

Saeed Asgary: Pubmed,Google Scholar