Ex Vivo Analysis of the Antimicrobial Effect of Diode Laser and Sodium Hypochlorite on Enterococcus Faecalis Atcc 29212.

Abstract

Introduction: The present study evaluated the efficacy of the diode laser in eliminating Enterococcus faecalis ATCC 29212 from root canals through ex vivo experiments.

Methods: Ninety single-rooted premolars were prepared with Endogal files, incubated anaerobically at 37ºC for 14 days, and randomly assigned to six groups (n=15 per group): G1: irrigation with 5.25% sodium hypochlorite (NaOCl); G2: NaOCl plus diode laser L1 (660 nm, 100 mW, 90 s); G3: NaOCl plus diode laser L2 (808 nm, 100 mW, 90 s); G4: L1 alone; G5: L2 alone; and G6: 0.9% sodium chloride (NaCl) as control. Root canal samples were collected using sterile paper points, and bacterial load was assessed by mass plating on Mueller‒Hinton agar, followed by incubation at 37ºC for 24 hours to quantify colony-forming units (CFU/mL).

Results: The combination of NaOCl and photodynamic therapy (PDT) (G2) significantly reduced bacterial counts compared with NaOCl alone (G1) (Z=2.89, adjusted P=0.01), and NaOCl combined with the 808 nm laser (G3) was significantly more effective than PDT alone (G4) (adjusted P<0.001). When applied without NaOCl, both laser-based protocols were significantly less effective than NaOCl alone: NaOCl (G1) produced significantly greater bacterial reduction than PDT alone (G4) (Z=-2.50, adjusted P=0.04), followed by the 808 nm laser alone (G5) (Z=-4.40, adjusted P<0.001).

Conclusion: The combination of 5.25% NaOCl with PDT produced the lowest E. faecalis counts and was significantly more effective than NaOCl alone, followed by the laser protocols applied without NaOCl. However, it did not differ significantly from NaOCl combined with the 808 nm laser, indicating that its advantage over other NaOCl-based protocols was numerical rather than statistically confirmed.