Aim: This study evaluated both smear layer removal and reduction of
Enterococcus faecalis after instrumentation with ultrasonic
irrigation. Methods: Root canals were experimentally inoculated with E.
faecalis for 20 days and microbiological samples were collected before
and after chemomechanical preparation by using sterilized absorbent
paper points. The irrigation solutions used were NaOCl 2.5% and EDTA
17%. In Group 1 (G1), conventional irrigation was used, whereas in
Group 2 (G2) ultrasonic irrigation was performed. In group 3 (control),
root canals were irrigated with distilled water. The samples were
inoculated in BHI broth and turbidity was observed after 48 h to
evaluate the reduction in the number of bacteria. Residual smear layer
was examined by scanning electron microscopy (SEM). Results: The
results showed no significant differences between ultrasonic and
conventional irrigation. Conclusions: It was concluded that the level
of disinfection and cleanliness of root canals achieved with ultrasonic
irrigation is comparable to that obtained by conventional methods