The Failing Root Canal

An endodondist recently told me that 70% of their practice is treating failed root canals!

A patient needing root canal repair may or may not be in pain or may or may not have swelling but the situation must always be addressed.

There are several reasons why a root canal can fail.  One possibility is that the clinician did not get to the end of the root and left some nerve tissue behind. The actual canal may have extra exits from the main canal which is off to the side and can be extremely difficult or impossible to access. I just spoke with a patient who has been in pain for a couple of years, and it turned out that the original clinician missed the fourth canal completely (this tooth has been successfully retreated and the patient is now out of pain).  In any case, a more experienced clinician, usually a trained endodontist (root canal specialist) can give the best chance of success with this.

Another cause of root canal failure is a root fracture, which is a big problem. If the root fractures, especially in the middle of the root, there usually is pain, and there is an indication on the x-ray that something is cracked. A CT scan is helpful with diagnosing a root fracture. If the fracture is right at the tip of the root, it is sometimes possible to perform an “apicoectomy” which is a surgical procedure to access the end of the root, remove the infection and cut off the tip of the root, and place a filling in the end of the root. I have seen many long term successes with this procedure. Most apicoectomies occur on front teeth.

Besides fractures, there can be severe curves in the root at the apex (end) that is impossible to access with current instrumentation where this additional procedure is the way to go.

Another cause of failure is when the root canal fillings leak and bacteria leak into the space that is supposed to be sealed. The treatment for this includes antibiotic therapy and a retreatment of the canal space to reestablish the seal. This condition should clear up with this approach as long as there is no fracture or missed canals.

If one canal of a molar totally fails and cannot be retreated, that root can be amputated and the other root saved. I have one patient with this, a lower second molar, that has last over 10 years. With the success of dental implants I see this much less frequently, but it still has its place for those insistent on keeping a tooth.

If none of the above treatments can work, the tooth needs to be extracted. Now the problem becomes how to replace the missing tooth, which is another situation all together.   Because there is so much to know about root canals, we work together with qualified specialist to ensure the best quality care.