Thulium, Erbium, and Diode Lasers for Intracanal Decontamination: Anti-Enterococcus faecalis Activity and Thermal Safety Ex Vivo.

Laser-assisted irrigation has emerged as a promising adjunct for root canal disinfection; however, evidence directly comparing different laser systems under standardized experimental conditions remains limited. This ex vivo study compared the antibacterial efficacy and thermal safety of an 808 nm diode laser, a 1940 nm thulium laser, and a 2940 nm erbium laser for intracanal decontamination against Enterococcus faecalis. Standardized infected human root canal specimens were treated using clinically relevant irradiation parameters. Antibacterial efficacy was evaluated by colony-forming unit (CFU) reduction and bacterial growth curve analysis, while thermal safety was assessed by measuring external root surface temperature changes during laser irradiation. All three laser systems demonstrated greater antibacterial activity than saline-treated controls. The erbium laser achieved the highest mean inhibition rate (99.0%) at 30 mJ for 30 s while maintaining external root surface temperature increases below the accepted 10°C thermal safety threshold. The thulium laser produced comparable antibacterial activity but exceeded the thermal safety threshold at its highest irradiation settings. The diode laser demonstrated lower antibacterial efficacy and greater temperature increases than the thulium and erbium lasers under the tested conditions. Within the limitations of this ex vivo model, the 2940 nm erbium laser demonstrated the most favorable balance between antibacterial efficacy and thermal safety and represents a promising adjunctive approach for intracanal disinfection.