SUBJECTS AND METHODS: Roots from human premolar teeth (n = 40) were infected with E. faecalis strain the American Type Culture Collection 29212 in brain heart infusion for 21 days. After the experimental period, specimens were divided into two groups, Group A (n = 20), Group B (n = 20), and Group A specimens were stained with fluorescein diacetate dye for the detection of viability and adherence Group B were stained with acridine orange dye for detection of metabolic activity and adherence. Samples were washed, thoroughly sectioned and examined by confocal laser scanning microscopy. Computer-assisted determinants of fluorescence, bacterial viability, metabolic activity, and adherence were compared statistically.
RESULTS: E. faecalis was able to invade the dentinal tubules to a depth of 1-400 μm and adhere to 1-200 μm depth. Adherence (90%) was significantly higher in 1-100 μm using fluorescein diacetate and acridine orange dye.
CONCLUSION: Adherence of E. faecalis as evaluated by confocal laser scanning microscope was highest at the depth of 1-100 μm which may have an impact on the shaping and cleaning procedures on the root canal.