title: Dentin inhibits the antibacterial effect of new and conventional endodontic irrigants.
abstract: BACKGROUND
  This in vitro study aimed to compare the antibacterial effect of a new irrigant, QMiX, with that of conventional irrigation solutions in the presence or absence of dentin powder.
  
  
  METHODS
  Dentin powder was prepared from bovine incisors and sterilized. The following irrigants were tested against Enterococcus faecalis (ATCC 29212): 6% sodium hypochlorite (NaOCl), 1% NaOCl, QMiX, 2% chlorhexidine gluconate (CHX), and 17% EDTA. Sterilized saline solution was used as negative control. Survival of bacteria exposed to the irrigants in the presence or absence of dentin was monitored under planktonic conditions. Colony-forming units were counted, and log-transformed numbers were analyzed by using Kruskal-Wallis and Mann-Whitney tests. P values less than .05 were considered significant.
  
  
  RESULTS
  In the absence of dentin, after 10 seconds of contact with the bacterial suspension, 6% NaOCl showed the lowest bacterial count; the difference to the negative control was significant. After 30 seconds, 6% NaOCl displayed 0 colony-forming units per milliliter, whereas 1% NaOCl and QMiX showed reduced number of colonies in comparison with the negative control. After 1 minute, both concentrations of NaOCl presented no bacterial growth and QMiX reduced the number of colonies, but EDTA and CHX had bacterial counts similar to the negative control. Dentin had a significant inhibitory effect on 6% NaOCl (10 seconds), 1% NaOCl (10 seconds and 1 minute), and QMiX (10 seconds and 1 minute). After 6 hours, both concentrations of NaOCl, QMiX, and CHX killed all bacteria, regardless of the presence of dentin.
  
  
  CONCLUSIONS
  Six percent NaOCl was the most effective irrigant against E. faecalis. Saline and EDTA had no measurable antibacterial effect. Dentin delayed the antibacterial activity of NaOCl and QMiX but did not completely prevent their action.
authors: Department of Endodontics, Pontifical Catholic University of Rio Grande do Sul, School of Dentistry, Porto Alegre, Brazil. remorgental@hotmail.com
authors: Renata Dornelles
authors: RD
authors: Morgental
authors: Aruna
authors: A
authors: Singh
authors: Harkeet
authors: H
authors: Sappal
authors: Patrícia Maria Poli
authors: PM
authors: Kopper
authors: Fabiana Vieira
authors: FV
authors: Vier-Pelisser
authors: Ove A
authors: OA
authors: Peters
mesh_terms: D000818:Animals; D000891:Anti-Infective Agents, Local / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D001645:Biguanides / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000494:pharmacology*; D002417:Cattle; D002710:Chlorhexidine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D015169:Colony Count, Microbial; D003804:Dentin / Q000502:physiology*; D004492:Edetic Acid / Q000494:pharmacology; D013293:Enterococcus faecalis / Q000187:drug effects; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology*; D012388:Root Canal Irrigants / Q000737:chemistry / Q000494:pharmacology*; D012973:Sodium Hypochlorite / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: D000891:Anti-Infective Agents, Local; D001645:Biguanides; D011108:Polymers; C557698:QMix root canal irrigant; D012388:Root Canal Irrigants; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D002710:Chlorhexidine