Antimicrobial activity of various 'active' gutta-percha points against Enterococcus faecalis in simulated root canals

Aim To test the antimicrobial activity of various gutta-percha points against Enterococcus faecalis in simulated root canals. Methodology Root canals were simulated by inoculated glass capillaries. A 2.5 mu L increment of a suspension of E. faecalis was placed into 10 simulated root canals together with Calcium Hydroxide(R) points (CHP), Calcium Hydroxide Plus(R) points (CH+P), active points(R) (AP), conventional gutta-percha points (CP) (Coltene Whaledent, Langenau, Germany) or no points (NP) (control) (each n = 2). The points and simulated root canals were flushed with 2 mL of sterile saline solution after 10 min or after 5 h of anaerobic incubation (37 degrees C, 100% humidity). Dilution sequences until 10(-3) and 10(-4) were prepared and plated on agar plates. The original suspension, diluted until 10(-6) and 10(-7), served as another control. The numbers of colony forming units were counted after 24 h. This experimental procedure was repeated 15 times. Results Without gutta-percha points, bacteria grew threefold in number within 5 h. With CHP and CH+P bacterial counts at 10 min and 5 h were approximately 50% compared with the control. AP killed all bacteria within 5 h. With CP, bacteria proliferated more than without points (counts at 5 h 177% of NP). Except for CHP versus CH+P differences between groups were statistically significant (Mann-Whitney test, P < 0.01). Conclusions In this experimental model, the potential of CHP and CH+P to kill E. faecalis was limited. CP stimulated bacterial growth. AP killed all bacteria after 5 h.