[Bactericidal effects and smear layer removal of Er:YAG-laser radiation against Enterococcus faecalis in root canals]

To evaluate the cleaning ability of Er:YAG laser against Enterococcus faecalis in root canals.
 Methods: The single-rooted human teeth were sterilized and inoculated with Enterococcus faecalis and were randomly assigned into 2 groups. A group of teeth was irrigated with saline during root canal preparation while another group with NaClO. After mechanical preparation, the two groups were randomly divided into 3 subgroups according to the different treatments: Samples, laser radiation, and calcium hydroxide intracanal medication for 7 days. Bactericical effects were compared among groups. Root canal walls and dental tubules were observed under scanning electron microscope.
 Results: Er:YAG laser was the most efficient way for anti-bacteria among the groups (P<0.05), but there was no significant difference between the 2 laser groups (P>0.05). Meanwhile the smear laser was efficiently removed by laser compared with other treatments, and the laser could open the dentinal tubules.
 Conclusion: Er:YAG laser can be effectively used for root canal disinfection without NaClO and Ca(OH)2.