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Diagnoses

Failing endodontic treatment

About this diagnosis

Diagnoses are associated with common findings which are used to prescribe appropriate treatment.

Alternate terms: Failing root canal.

Sometimes teeth which have been endodontically treated (i.e. have had root canal therapy) become re-infected, and require retreatment. The most common causes of root canal failures are broken or leaking restorations, recurrent caries, and crowns which are poorly adapted to the tooth. Less than 10% of endodontically treated teeth are lost to failure of the root canal treatment itself. Among endodontically treated teeth which require removal, most (~60%) are lost to failure of the restoration (crown, etc.). About 30% are lost to periodontal disease.

Endodontic re-treatment involves the same steps as initial endodontic treatment, with the added complexity of removing the existing root canal filling material and any structural posts or other materials which have been placed in the tooth to reinforce its strength.

View animation Apicoectomy

Failing endodontic or root canal treatment of a tooth with a prefabricated post and core.

Figure 1: Development of a recurrent infection at the apex of a previously treated molar tooth is illustrated. Sometimes the problem does not produce pain or other symptoms, and a lesion is noted only on a routine follow-up X-ray image of the tooth. It can be difficult to tell whether the lesion is from the original infection, or a failing root canal treatment. Often, the original lesion will develop a clearly visible demarcation (cortication) line around it as it heals, forming what is known as an apical scar. If such a feature can be observed radiographically, and doesn't appear to change over time, it may not be necessary to retreat the tooth.