With proper care, most endodontically treated teeth can last as long as other natural teeth. In some cases, a tooth that has receive endodontic treatment fails to heal, or becomes diseased months or even years after successful treatment. This may occur for a number of reasons: narrow canals or complicated anatomy not cleaned out during initial treatment, delayed placement of the permanent restoration after initial treatment or the permanent restoration not preventing salivary contamination. Also, new decay, tooth cracks, or loose or broken fillings can expose the root canal filling material to bacteria, causing a new infection in the tooth
Improper healing may be caused by:
Curved or narrow canals were not treated during the initial treatment.
Complicated canals went undetected during the initial treatment.
The crown or restoration was not placed within the appropriate amount of time following the procedure.
The crown or restoration did not prevent saliva from contaminating the inside of the tooth.
As with the primary root canal treatment, the tooth will be numbed and the rubber dam placed. In many cases, complex restorative materials – crown, post and core – must be removed to permit access to the root canals. After removing the canal filling, the endodontist can disinfect the canal spaces and carefully examine the inside surfaces for any additional canals, perforations, fractures and decay using microscope magnification. If the tooth is deemed restorable, the root canals are filled and the treatment is finished in the same fashion as during the primary treatment and the access is sealed with a temporary filling. As with the primary treatment, you must return to your dentist as soon as possible to have a crown or other restoration placed on the tooth to protect and restore it to full function.
While non-surgical re-treatment can usually be utilized to address failing primary treatment, there are some situations where proper re-treatment cannot be accomplished with a desired outcome. These include:
Complex restorations with large posts may not be amenable to removal without fracturing the root. Thus access into root canals cannot be gained
Complex internal anatomy prevents adequate disinfection of root canal spaces
Re-treatment has been completed without desired healing.
In those situations, endodontic surgery may save the tooth.
To provide you with a better understanding of endodontic retreatment, we have provided the following multimedia presentation.