The effect of sodium hypochlorite on the elimination of E. Faecalis using rotary instrumentation and intermittent passive ultrasonic irrigation

OBJECTIVE: The purpose of this study was to evaluate in vitro the effect of different variables (delivery system, surface contact with the irrigant, the frequency of changing the irrigant and the total volume of the irrigant) of sodium hypochlorite on the elimination of E. faecalis using rotary instrumentation and intermittent passive ultrasonic irrigation (IPUI). MATERIALS and METHODS: Sixty extracted single-rooted teeth were instrumented up to size 20 K-file, then inoculated with E. faecalis. The root canals were prepared up to a # 40 using 0.04 profile rotary files and irrigated with 2 ml of 2.25% NaOCl. Ultrasonic P5 with NiTi file # 25 was oscillated for 30 seconds after # 30 file, at the end of the preparation, and after NaOCl was left in situ for 5 minutes to complete 15 minutes of preparation. A total volume of 10 ml of sodium hypochlorite was used. The root canals were divided equally into four experimental and one control groups. In Group I, pipette was used to deliver the irrigant; Group II, the total contact time of irrigant was 30 minutes; Group III, the canal was flushed every 2 minutes; Group IV, the total volume of the irrigant was 20 ml and in Group V (control), chemo-mechanical preparationwas carried out without IPUI. The root canals were sampled before and after instrumentation and the zone of bacterial growth were measured in mm and recorded. RESULTS: A significant bacterial reduction was demonstrated in Groups I (P=0.020), II (P=0.001), and IV (P=0.000) as compared to Groups III and V. CONCLUSIONS: The results of this study showed that the flushing action, the larger volume of sodium hypochlorite irrigant and the increase in the contact time of the irrigant combined with rotary instrumentation and IPUI enhanced the elimination of E. faecalis from the root canal.