Does supplemental photodynamic therapy optimize the disinfection of bacteria and endotoxins in one-visit and two-visit root canal therapy? A randomized clinical trial

Aim To evaluate the effectiveness of supplemental photodynamic therapy (PDT) in optimizing the removal of bacteria and endotoxins from primarily infected root canals after one-visit and two-visit treatments. Methodology: Twenty-four primarily infected root canals with apical periodontitis were selected and randomly divided into one-visit (n = 12) and two-visit treatment groups (n = 12). Chemo-mechanical preparation (CMP) was performed by using the single-file reciprocating technique + 2.5% NaOCL and a final rinse with 17% EDTA. The photosensitizer agent (methylene blue 0.1 mg/mL) was applied to root canals for 60 s before application of laser with a potency of 60 mW and energy density of 129 J/cm(2) for 120 s after CMP in the one-visit treatment and after 14-day inter-appointment medication with Ca(OH)(2) + Saline solution (SSL) in the two-visit treatment. Samples were collected before and after root canal procedures. Endotoxins were quantified by chromogenic limulus amebocyte lysate assay. Culture techniques were used to determine bacterial colony-forming unit counts. Results: Bacteria and endotoxins were detected in 100% of the initial samples, with median values of 1.97 x 10(5) CFU/mL and 24.983 EU/mL, respectively. The CMP using single-file reciprocating technique was effective in the reduction of bacteria and endotoxins (All, p < 0.05). The supplemental PDT was effective in reducing bacterial load in the one-visit (p < 0.05) but not in the two-visit treatment after use of Ca(OH)(2) medication for 14 days (p > 0.05). In the two-visit group, after 14 days of inter-appointment medication with Ca(OH)(2), a significant reduction in the median levels of endotoxins was found in comparison to CMP alone (from 1.041 to 0.094 EU/ mL) (p < 0.05). Despite the type of treatment, the supplemental PDT was not effective against endotoxins (p > 0.05). Conclusions: The photodynamic therapy optimized the disinfection of bacteria from root canals in one-visit but not for two visit treatment modality with the accomplishment of calcium hydroxide medication. Despite the type of treatment, the supplemental PDT was, not effective against endotoxins.