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Updated: Jun 14, 2026
LED-Based In Vitro Screening for Assessing Photoactivable Molecules in Bacterial Photodynamic Inactivation
Published on: January 24, 2025
Endodontic photoactivated disinfection using a conventional light source: an in vitro and ex vivo study
Sebastian Schlafer1, Michael Vaeth, Preben Hørsted-Bindslev
1School of Dentistry, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark. sebastian.schlafer@hotmail.de
Objective:
The antimicrobial effect of photoactivated disinfection (PAD) using toluidine blue and an LED lamp was tested on endodontic pathogens in planktonic suspension and after inoculation into extracted teeth. Irradiation time was limited to 30 seconds.
Study Design:
The effect of PAD on planktonic suspensions of Escherichia coli, Candida albicans, Enterococcus faecalis, Fusobacterium nucleatum, and Streptococcus intermedius was analyzed using Poisson regression. Moreover, cultures of S. intermedius were inoculated into prepared root canals of extracted molars. The effect of PAD performed immediately after inoculation or after overnight bacterial incubation was determined by a 2-sample t test.
Results:
Photoactivated disinfection yielded significant reductions (P < .001) in the viable counts of all organisms in planktonic suspension. The PAD treatment of S. intermedius in root canals yielded a mean log10 reduction of 2.60 (P < .001) immediately after inoculation and of 1.38 (P < .001) after overnight incubation.
Conclusion:
Photoactivated disinfection using a conventional light source strongly reduces the number of viable endodontic pathogens in planktonic suspension and in root canals.
