Endodontic retreatment describes a dental

Dentistry

Dentistry is the branch of medicine that is involved in the study, diagnosis, prevention, and treatment of diseases, disorders and conditions of the oral cavity, maxillofacial area and the adjacent and associated structures and their impact on the human body. Dentistry is widely considered...

 root canal procedure procedure that is carried out on a tooth

Tooth

Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...

 that has previously had root canal treatment. For this reason it is also called "repeat root canal treatment".

One reason for endodontic retreatment is failure of the initial endodontic procedure: Recurrence of symptoms, infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

 such as dental abscess may occur.

Endodontic treatment may fail for many reasons: one common reason for failure is inadequate chemomechanical debridement

Debridement

Debridement is the medical removal of a patient's dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue...

 of the root canal

Root canal

A root canal is the space within the root of a tooth. It is part of a naturally occurring space within a tooth that consists of the pulp chamber , the main canal, and more intricate anatomical branches that may connect the root canals to each other or to the surface of the root.-Root canal anatomy:...

. This may be due to poor endodontic access, missed anatomy

Anatomy

Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant 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

Gutta-percha

Gutta-percha is a genus of tropical trees native to Southeast Asia and northern Australasia, from Taiwan south to the Malay Peninsula and east to the Solomon Islands. The same term is used to refer to an inelastic natural latex produced from the sap of these trees, particularly from the species...

 is contaminated with oral bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

. 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

Enterococcus faecalis

Enterococcus faecalis – formerly classified as part of the Group D Streptococcus system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans and other mammals. It is among the main constituents of some probiotic food supplements. Like other species in the genus...

 and/or other facultative enteric bacteria or Pseudomonas

Pseudomonas

Pseudomonas is a genus of gammaproteobacteria, belonging to the family Pseudomonadaceae containing 191 validly described species.Recently, 16S rRNA sequence analysis has redefined the taxonomy of many bacterial species. As a result, the genus Pseudomonas includes strains formerly classified in the...

 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

Dentist

A dentist, also known as a 'dental surgeon', is a doctor that specializes in the diagnosis, prevention, and treatment of diseases and conditions of the oral cavity. The dentist's supporting team aides in providing oral health services...

. Complex retreatment cases may be referred to a specialist endodontist. Use of an operating microscope

Operating microscope

An operating microscope is an optical microscope specifically designed to be used in a surgical setting, typically to perform microsurgery.Design features of an operating microscope are: magnification typically in the range from 4x-40x, components that are easy to sterilize or disinfect in order to...

or other magnification may improve outcomes.