Reduction in Antimicrobial Substantivity of MTAD After Initial Sodium Hypochlorite Irrigation

Franklin R. Tay, Noriko Hiraishi, George S. Schuster, David H. Pashley, Robert J. Loushine, Hani F. Ounsi, Simone Grandini, Joyce Y.Y. Yau, Annalisa Mazzoni, Adam Donnelly, Nigel M. King

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Potential intrinsic tetracycline staining of intraradicular dentin has been observed when BioPure MTAD was employed as the final irrigant after initial rinsing with NaOCl. This study examined the effect of NaOCl-MTAD interaction on the antimicrobial substantivity of MTAD in dentin. Dentin cores previously irrigated with either MTAD, or in conjunction with 1.3% NaOCl as an initial irrigant were placed on blood agar plates inoculated with Escherichia faecalis at 105 cfu/ml. Dentin cores irrigated with 1.3% NaOCl only, and autoclaved dentin disks were used as the respective positive and negative controls. After anaerobic incubation, the mean diameter of bacterial inhibition zones formed around the MTAD group was significantly larger than the NaOCl/MTAD group, which, in turn, was not significantly different from the NaOCl positive control. Oxidation of MTAD by NaOCl resulted in the partial loss of antimicrobial substantivity in a manner similar to the peroxidation of tetracycline by reactive oxygen species.

Original languageEnglish (US)
Pages (from-to)970-975
Number of pages6
JournalJournal of endodontics
Issue number10
StatePublished - Oct 2006


  • Antimicrobial potency
  • Escherichia faecalis
  • MTAD
  • doxycycline
  • oxidation
  • sodium hypochlorite

ASJC Scopus subject areas

  • Dentistry(all)


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