Endodontic retreatment describes a root canal procedure that is carried out on a tooth that has previously had root canal treatment.
The most common reason for endodontic retreatment is failure of the initial endodontic procedure. Endodontic treatment may fail for many reasons:
Inadequate removal of the debris and infected tissues during the root canal therapy.
Poor endodontic access : the files have no adequate access to all the areas of the root canal.
Inadequate shaping of the canal, particularly in the apical third of the root canal.
The dentist does not find all of the root canals within a tooth.
Inaccurate root canal filling : the root canal passages have not been completely filled, the canal filling does not fully extend to the apex of the tooth, or it does not fill the canal as densely as it should.
If the tooth is not perfectly sealed, the root canal may leak, causing eventual failure of the root canal therapy.
Procedural accidents : instruments may separate (break) during root canal treatment, a tooth root may be perforated while the root canal is being treated etc.
The common cause of endodontic failure is that root canal filling is contaminated with oral bacteria. Over time, this will cause infections that will spread in the surrounding tissues leading to chronic or acute inflammations of the periapical tissue.
Signs and symptoms
Sometimes, after the failure of the initial endodontic procedure, an acute infection (that may develop into a dental abscess) may occur. This can cause severe pain, the area may be sensitive to touch and (in case of a dental abscess) it is normally swollen.
Very often, endodontic failure occurs without the patient's knowledge as it develops into chronic apical infections (such as a dental cyst or an apical granuloma) which are normally asymptomatic (they do not cause any pain).
In these cases, the dentist can determine the correct diagnosis only after dental X-rays are taken.
In the image above, the initial endodontic procedure failed because the canal filling does not extend to the apex of the tooth. The dark area underneath the roots signifies a chronic bone infection.
Endodontic retreatment procedure
Endodontic retreatment is technically demanding ; typically, success rates are lower compared to initial root-canal treatment. Therefore, if there is an extensive loss of tooth structure or bone infection is very advanced, extraction may be the more prudent approach.
Endodontic retreatment procedure involves the removal of the contaminated root canal filling that will be replaced in a retreatment procedure that generally follows the steps of a traditional root canal therapy.
If the procedure was carried out correctly, majority of the lesions can undergo resolutions following retreatment therapy because the causative agents were removed from the canal passages.
before endodontic retreatment
after endodontic retreatment
In the images above, the endodontic retreatment was meticulously carried out. The root canals have been completely filled with gutta-percha and the root canal filling fully extends to the apex of the root canals.
Consequently, the apical lesion (the dark area below the roots) underwent a major resolution.
Endodontic retreatment can take more time than the initial endodontic procedure and can be more expensive.
Complex retreatment cases may be referred to a specialist endodontist. Use of an operating microscope or other magnification may improve outcomes.
Last review and update: November 2020