Antibacterial Effectiveness of 2 Root Canal Irrigants in Root-filled Teeth with Infection: A Randomized Clinical Trial

J Endod. 2016 Sep;42(9):1307-13. doi: 10.1016/j.joen.2016.06.006. Epub 2016 Jul 21.


Introduction: This study compared the antibacterial effects of 1% sodium hypochlorite (NaOCl) and 2% chlorhexidine digluconate (CHX) during retreatment of teeth with apical periodontitis.

Methods: Root canal-treated teeth with apical periodontitis were randomly distributed into 2 groups. Bacteriological samples were taken from the canals before (S1) and after (S2) preparation using either NaOCl or CHX irrigation and after calcium hydroxide medication (S3); 16S ribosomal RNA gene-based real-time quantitative polymerase chain reaction was performed to quantify total bacteria, streptococci, and Enterococcus faecalis.

Results: Forty-nine teeth were available for analysis (NaOCl, n = 20; CHX, n = 29). Bacterial DNA occurred in all S1 samples, streptococci in 57% and E. faecalis in 6%. The total bacterial counts decreased from S1 to S2 in both groups (P < .01) but were higher in S3 than S2 (P < .01). Thirty-five percent of the teeth in the NaOCl group were positive in S2, decreasing to 20% in S3. In the CHX group, 41% were positive in S2, decreasing to 31% in S3. The bacterial load in S1 influenced the incidence of bacteria in S2 (P < .01). Streptococci were significantly reduced in both groups, and E. faecalis was found in only 1 S2 sample and not in S3. No significant difference between NaOCl and CHX was found.

Conclusions: NaOCl and CHX both reduced bacterial counts and the number of infected canals. Intracanal medication with calcium hydroxide reduced the number of canals with persistent infection but resulted in overall larger bacterial counts in the cases positive for bacteria. The effectiveness of antimicrobial treatment can be influenced by the initial bacterial load.

Keywords: 16S ribosomal RNA gene; calcium hydroxide; chlorhexidine; endodontic retreatment; post-treatment apical periodontitis; quantitative real-time polymerase chain reaction; sodium hypochlorite.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / therapeutic use*
  • Bacterial Load / drug effects
  • Chlorhexidine / analogs & derivatives
  • Chlorhexidine / therapeutic use
  • Dental Pulp Cavity / microbiology
  • Enterococcus faecalis / drug effects
  • Enterococcus faecalis / genetics
  • Female
  • Gram-Positive Bacterial Infections / drug therapy
  • Humans
  • Male
  • Middle Aged
  • Periapical Periodontitis / surgery*
  • Real-Time Polymerase Chain Reaction
  • Root Canal Irrigants / therapeutic use*
  • Sodium Hypochlorite / therapeutic use
  • Streptococcal Infections / drug therapy
  • Streptococcus / drug effects
  • Streptococcus / genetics
  • Young Adult


  • Anti-Bacterial Agents
  • Root Canal Irrigants
  • Sodium Hypochlorite
  • chlorhexidine gluconate
  • Chlorhexidine