Root canal re-treatment involves removing the existing root filling, finding all of the root canals, and then continues the root canal treatment. Special attention needs to be given to the cause of the failure of the original treatment and resolve this. It may be extra canals in the tooth containing either inflamed nerve tissue or infection, flexing cusps causing leakage, decay around the restoration, or a leaking root filling.
There is more time needed to treat these teeth so the cost is usually greater. As well, the tooth is weaker than other teeth so your specialist will discuss this with you before treatment is started.