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Toxicity of concentrated sodium hypochlorite used as an endodontic irrigant


Dr Christian Gernhardt, Department of Operative Dentistry and Periodontology, University School of Dental Medicine, Martin-Luther-University Halle-Wittenberg, Grosse Steinstrasse 19, D-06108 Halle, Germany (Tel.: +49 345 5573762; fax: +49 345 5573773; e-mail:


Aim  To present a clinical case that illustrates the toxicity of concentrated sodium hypochlorite (NaOCl) on vital tissues.

Summary  The severe clinical consequences of extruding concentrated NaOCl into the periradicular tissues during root canal irrigation are described. After diagnosis of external resorption in tooth 34, endodontic treatment was initiated. Following irrigation with a concentrated NaOCl solution, a rapidly developing swelling and haematoma were visible. During the next few days, an extensive bruise and local necrosis of the oral mucosa developed. After healing of the involved tissues, the canal was prepared and obturated. At this time, no clinical symptoms remained.

Key learning points

  • • The use of concentrated NaOCl as a root canal irrigant might cause severe clinical problems when extruded into vital tissues.
  • • The present report confirms the known toxicity of NaOCl to soft tissues following inadvertent extrusion.
  • • To avoid extrusion, it is always prudent to confirm the length and integrity of the root canal system before irrigating with concentrated solutions.