title: Antimicrobial efficiency of photodynamic therapy with different irradiation durations.
abstract: OBJECTIVE
  This study aimed to evaluate the antimicrobial efficiency of PDT and the effect of different irradiation durations on the antimicrobial efficiency of PDT.
  
  
  METHODS
  Sixty freshly extracted human teeth with a single root were decoronated and distributed into five groups. The control group received no treatment. Group 1 was treated with a 5% sodium hypochlorite (NaOCl) solution. Groups 2, 3, and 4 were treated with methylene-blue photosensitizer and 660-nm diode laser irradiation for 1, 2, and 4 min, respectively. The root canals were instrumented and irrigated with NaOCl, ethylenediamine-tetraacetic acid, and a saline solution, followed by autoclaving. All the roots were inoculated with an Enterococcus faecalis suspension and brain heart infusion broth and stored for 21 days to allow biofilm formation. Microbiological data on microorganism load were collected before and after the disinfection procedures and analyzed with the Wilcoxon ranged test, the Kruskal-Wallis test, and the Dunn's test.
  
  
  RESULTS
  The microorganism load in the control group increased. The lowest reduction in the microorganism load was observed in the 1-min irradiation group (Group 2 = 99.8%), which was very close to the results of the other experimental groups (99.9%). There were no significant differences among the groups.
  
  
  CONCLUSIONS
  PDT is as effective as conventional 5% NaOCl irrigation with regard to antimicrobial efficiency against Enterococcus faecalis.
authors.affiliation: Departments of Endodontics, Faculty of Dentistry, Gaziantep University, Gaziantep, Turkiye.
authors.forename: Cihan
authors.initials: C
authors.lastname: Yildirim
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Gaziantep University, Gaziantep, Turkiye.
authors.forename: Emine Sirin
authors.initials: ES
authors.lastname: Karaarslan
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Gaziantep University, Gaziantep, Turkiye.
authors.forename: Semih
authors.initials: S
authors.lastname: Ozsevik
authors.affiliation: Department of Microbiology, Faculty of Medicine, Gaziantep University, Gaziantep, Turkiye.
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Zer
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Bezmialem Vakif University, Istanbul, Turkiye.
authors.forename: Tugrul
authors.initials: T
authors.lastname: Sari
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Bezmialem Vakif University, Istanbul, Turkiye.
authors.forename: Aslihan
authors.initials: A
authors.lastname: Usumez
keywords: Enterococcus faecalis; irradiation duration; methylene blue; photodynamic therapy