Occasionally, an endodontically treated (devitalized) tooth, may not heal or continue to be painful in spite of therapy, even after months or years. Very often, when this happens, the tooth may be salvaged by a second endodontic treatment: a retreatment.

Why it’s necessary to retreat root canals

Endodontic treatment is performed because the pulp, commonly called nerve by patients, has been irreparably damaged. Even though the pulp has been removed and replaced with an obturation material, the tooth has to be retreated when problems caused by one or more of the following reasons arise:

Incomplete cleansing and obturation of the root canals

For an endodontic treatment to be successful, the root canals have to be wholly cleansed, disinfected and obturated in their entireness. Occasionally some canals are so thin, calcified or curved, that the smallest instruments available (8 hundredths of a millimetre at their tip)  are not able to enter and clean them. Other root canals have entrances that are so small, that they aren’t easily found unless you use a microscope, while other canals may present badly performed obturations. Lastly, in inexperienced hands, a metallic instrument may break inside the canal, preventing cleansing and obturating beyond the fragment if it is left there.

Radicular trauma

Recent trauma may have caused the root to fracture and a new infection may have developed at the root apex (tip). Recent caries may have damaged the tooth’s crown exposing the obturation material in the root canals to bacteria and saliva, causing a new infection of the root canals. A fracture, a cracked filling, an uncemented crown or radicular post or even the simple loss of a temporary filling while waiting for the definitive restoration may determine the exact same outcome, causing what is defined as “coronal infiltration” and requiring a retreatment.

Who may perform retreatments

Every dentist has the necessary training to perform a retreatment. Many cases, however, are very complex and require the intervention of specialists who dedicate most of, or all of, their professional practice to Endodontics and who therefore are more skilled in performing the aforementioned therapies and have access to more sophisticated and up-to-date equipment. As already mentioned, the root canal spaces in which the work needs to be done are very thin and many problems will only be able to be solved exclusively with the help of an operatory microscope (Fig. 9).

Dott. Arnaldo Castellucci al microscopio durante una procedura di ritrattamento endodontico

Today in fact this instrument is used in all the phases of an endodontic treatment and it is even more so during retreatments and surgery.

What happens during a retreatment

The tooth has to be re-opened, the root canals have to be sounded, cleansed and obturated all over again. When all of this isn’t possible (presence of previous ledge formation, obstacles in the canals, old obturation materials that can’t be removed with common solvents, etc.) a gingival incision that will allow exposure of the tooth apex might be required, so as to seal it (apicoectomy and retrograde obturation) by means of a surgical access.

Patients may experience post-operative pain.

The tooth may be slightly painful after the retreatment has been performed. This inconvenience does not compromise the therapy’s success. Since the first treatment failed, how can a patient be sure that the retreatment will be successful. Naturally there aren’t any guarantees. Retreatments are often the only alternative to surgery (apicoectomy with retrograde obturation of the root apex) or tooth extraction. A dentist will certainly provide his patient with all the information and the treatment alternatives so that he may make an informed and serene decision.

The alternatives to retreatment

As already mentioned, the first alternative consists in an apicoectomy with retrograde obturation of the root apex. This will always be possible as long as there is an adequate surgical access and it also has a high success rate. The second alternative is tooth extraction. The loss of a tooth, however, may determine movement of the surrounding teeth and severe occlusal and masticatory interferences. The missing tooth may be replaced with a bridge that is fixed to any remaining teeth that are close by, or with an implant in the bone. These procedures are all very time consuming, expensive and artificial. Nothing is currently better or will last as long as a natural tooth. In some cases, if retreatment or the apicoectomy is not possible, then if conditions of the tooth will allow it, an immediate intentional tooth re-implantation may be possible, or in other words the extraction of the tooth, management of the cause of the lesion, treatment of the root while holding the tooth in hand and final tooth re-implantation in it’s alveolar socket. The long term prognosis, however, is not among the most favourable.

The cost of retreatment

Generally the fee for a retreatment is higher than the fee for a normal tooth devitalization. This is due to the increased difficulty, the extended operative time and the larger amount of equipment required to achieve a successful outcome.

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