Effect of Temperature, Concentration, and Contact Time of Sodium Hypochlorite on Enterococcus Faecalis

Background and Aim: To compare time, concentration and temperature dependent antimicrobial activity of sodium hypochlorite (NaOCl) against Enterococcus faecalis (E. faecalis). Materials and Methods: A total of 144 antibiotic discs were infected by E. faecalis; 6 antibiotic discs served as negative controls. Discs were further divided into 12 subgroups according to 2 contact times (1and 5min) and 2 concentrations (2.5% and 5 %) with NaOCl at 3 different temperatures (25°C, 37°C or 45°C). Growth of the bacteria was observed after 48 h following incubation under normal atmosphere conditions at 37°C. Statistical analysis was performed using the multiple logistic regression (p<0.05). Results: There were no significant differences between the contact times and concentrations tested (p=0.316 and p=0.052, respectively). However, there was a statistically significant difference among temperatures tested (p<0.001). Conclusion: Growth of E. faecalis is dependent on the temperature of NaOCl. It could be advantageous to irrigate root canals with NaOCl that has higher temperature than room temperature, especially during the treatment of persistent periapical infections.