Comparative analysis of antimicrobial activity and oxidative damage induced by laser ablation with indocyanine green versus aPDT with methylene blue and curcumin on E. coli biofilm in root canals.

Laser ablation and Antimicrobial Photodynamic Therapy (aPDT) serve as adjunctive treatments to enhance microbial reduction in endodontic root canals. This in vitro study assessed laser ablation with Indocyanine Green (ICG) compared to aPDT using Methylene Blue (MB) and Curcumin (CUR) photosensitizers for reducing E. coli biofilms and inducing oxidative damage in root canals. Methods Standardized bovine upper incisor roots (n = 100) were contaminated with E. coli for 10 days to form biofilms. Groups included ICG 0.05% activated by infrared diode laser, CUR 0.05% activated by blue LED, MB 0.01% activated by red laser, sterile saline (NC), and 2.5% sodium hypochlorite (PC). Root canal samples were collected pre- and post-treatment, plated on BHI agar for CFU/mL counting. Oxidative damage was assessed using TBARS and carbonylated protein methods. Percentage reduction data underwent two-way ANOVA and Student-Newman-Keuls test, Kruskal-Wallis, and Dunn's tests for CFU reduction, and one-way ANOVA (p < 0.05) for oxidative damage. Results No statistical differences were found among groups for E. coli reduction. All groups had higher reduction than NC and lower reduction than PC (p < 0.05). ICG and CUR showed higher oxidative damage than MB and controls in protein carbonyl analyses. In TBARS analysis, ICG exhibited the greatest oxidative damage, statistically higher than other photosensitizers, negative, and positive controls. Conclusion There was no difference between laser ablation with ICG and aPDT with CUR and MB, which were less effective in bacterial reduction than NaOCl. However, ICG-induced higher oxidative damage in Gram-negative bacteria, suggesting its potential as an adjunctive therapy in root canal procedures.