Efficacy Of Sodium Hypochlorite As Endodontic Irrigation In Reducing Enterococcus Faecalis Within Root Canals

Object: This experiment evaluates the efficacy of 5.25%sodium hypochlorite (NaClO) as endodontic irrigation solution against Enterococcus faecalis within root canals.Method: A total of 20 extracted human mandibular premolar teeth with a single root canal, were dealed with standard technique.The teeth were placed into glass tubes containing enterococci medium and autoclaved. The root canals of twenty extracted teeth were infected by Enterococcus faecalis in vitro, and then cultured in enterococci medium. The teeth were instrumented using sterile stainless steel K-files up to size 40 with standardization . Twenty extracted human premolars were randomly and evenly divided into 5.25% sodium hypochlorite, 0.9% sterile saline solution(NaCl), each group 10 premolars. Canals were sampled after instrumentation using sterile paper points, and then incubated at 37℃.The colony forming units (CFU) grown were counted at 24h, 48h and 1week.Result: At 24 hour, 48 hour, Enterococcus faecalis in 5.25% sodium hypochlorite group were completely killed, and the colony forming units were 0 CFUml-1. The average colony forming units of the NaCl group were respectively 1.2×106 CFUml-1, 1.7×106 CFUml-1 . There were significant differences between the two tested groups (P< 0.01).At 1 week, few Enterococcus faecalis were detected. The average colony forming units of the 5.25% sodium hypochlorite group was 109 CFUml-1 and the NaCl group was 3.8×106 CFUml-1 . There were significant differences between the two tested groups (P< 0.01).Conclusion:5.25% sodium hypochlorite endodontic irrigation solution can immediately kill Enterococcus faecalis, but it can not clean up the Enterococcus faecalis completely. Sodium hypochlorite only can reduce the amount of the Enterococcus faecalis,and make it in bacteriostasis within a period of time.