If ordinary root canal treatment (endodontic therapy) has been unsuccessful in eliminating the infection in a tooth, sometimes root canal surgery may be required.
Endodontic treatment is performed when the inner tissue, the pulp tissue, of a tooth is infected. In this treatment, the infected pulp tissue is removed and is replaced with an inert substance, usually gutta percha.
If the apical seal is inadequate, bacteria can get in and out of the root canal space and the infection will be renewed. When this happens, you will have a tooth abscess, and it is said that the treatment has failed.
There are two remedies available for treating a failed root canal:
Re-treat the tooth, removing the old gutta percha, improving the preparation inside the tooth, and placing new gutta percha in an attempt to get a better apical seal. Or you can have root canal surgery.
With this treatment, the dentist enters through the gum and bone directly to the end of the root, or what is called the apex. The very tip of the root is then removed. When this tip is the source of the infection, this can often cure the infection. The name for this endodontic surgery procedure is an apicoectomy, which means the removal of the apex. It is easiest to perform on teeth that are closest to the front of the mouth.
Often the tips of the roots of the teeth are very close to the surface of the gum. While the description of the surgery sounds awful, it is actually often a very simple procedure with minimal post-operative swelling and a short recovery time. Patients can often return to their normal activities the next day.
What is a retrofill?
Sometimes, accompanying the apicoectomy, the dentist will place a small filling at the end of the root, called a retrofill. The purpose of the retrofill is to help seal this opening from any bacteria leaking in or out.
When the failure is on a lower molar, surgery may not be an option. Not only are the roots of these teeth difficult to get to surgically, but they also lie very near the nerve that goes to the lower teeth and the lip. Surgery that risks damage to this nerve may not be wise.
While surgery is often successful, there are many times when it is not successful. The chance for success for surgery is probably somewhere between 50% and 75%. It's best for patients to go into the surgery braced for the possibility that the treatment may fail and the tooth will have to be extracted.
Just because there is post-operative root canal pain doesn't mean that surgery is required. Post-operative pain is not uncommon and may not indicate that anything is wrong.
Read Dr. Hall's blog post about a broken root canal file.