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Endodontic retreatment describes a dental root canal procedure that is carried out on a tooth that has previously had root canal treatment. For this reason it is also called "repeat root canal treatment".
Endodontic treatment may fail for many reasons: one common reason for failure is inadequate chemomechanical debridement of the root canal. This may be due to poor endodontic access, missed anatomy or inadequate shaping of the canal, particularly in the apical third of the root canal.
Exposure of the obturation material to the oral environment may mean the gutta-percha is contaminated with oral bacteria. If complex and expensive restorative dentistry is contemplated then ideally the contaminated gutta percha would be replaced in a retreatment procedure to minimise the risk of failure.
The type of bacteria found within a failed root canal may differ from the normal infected tooth. Enterococcus faecalis and/or other facultative enteric bacteria or Pseudomonas sp. are found in this situation.1
Endodontic retreatment is technically demanding; typical 5 year success rates are around 60% compared to around 85% for initial root-canal treatment. It can be time consuming procedure also as meticulous care is required by the dentist. Complex retreatment cases may be referred to a specialist endodontist. Use of an operating microscope or other magnification may improve outcomes.