Comparison of antibacterial and toxic effects of various root canal irrigants

To compare the antibacterial properties and toxicity of 5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine gluconate and 0.2% chlorhexidine gluconate plus 0.2% cetrimide (Cetrexidin); Vebas, San Giuliano, Milan, Italy).

The antibacterial effects of the irrigants in vitro were examined after 5 min and 48 h in freshly extracted human teeth with single roots, whose canals were infected by Enterococcus faecalis ATCC 29212. In a separate in vivo study, bacterial culture samples were collected before treatment from the infected root canals of deciduous teeth containing necrotic pulp tissue. Irrigants were used to clean the canals which were then left empty for 48 h. Aerobic/facultative anaerobic and anaerobic bacterial growth were compared before and 48 h after irrigation. Finally, the toxic effects of the irrigants were assessed by injecting them into the subcutaneous tissues of rats. The inflammatory reactions that occurred 2 h, 48 h and 2 weeks after the injections were evaluated.

In the laboratory study, the 2% chlorhexidine gluconate and Cetrexidin were significantly more effective on E. faecalis than the 5.25% NaOCl at 5 min (P < 0.05). Similarly, in the in vivo study, 2% chlorhexidine gluconate and Cetrexidin were significantly more effective on anaerobic bacteria than the 5.25% NaOCl at 48 h (P < 0.05). At the end of 2 weeks, the toxicity of the NaOCl solution was greater than that of the other irrigants (P < 0.05).

Cetrexidin and 2% chlorhexidine gluconate were more effective, and had more residual antibacterial effects and lower toxicity than 5.25% NaOCl solution.