Expert: Howard Finnk, D.D.S., P.A., CEO - 7/3/2009

Question
QUESTION: Hello Dr. Finnk,

I am wondering, how does a dentist know if a root canal is failing or not? Does x-raying the tooth show if the root canal is properly filled up or not? Can it also show if it is successful? What if the patient still has symptoms such as pain, and such? Is that an indication a root canal is failing?



Secondly, I want to ask, if a root canal was successful, whatever infection that was on the bone prior to the root canal, will heal and go away, correct? So there shouldn't be any reason why the infection would still be there if the root canal was successful?



Now, what is this concept about, is it one of those deals where even if the dentist gives the tooth their best effort, the root canal can still fail? How can that happen, because I thought if the dentist did it correctly, it should have no reason to fail.

Thanks, hear from you soon.

ANSWER: Dear d:  A tooth with a root canal should experience no pain and no swelling around it.  On xray, a failed root canal might have dark areas surrounding the ends of the roots, or a dark area between the roots.  This indicates probable infection in the bone surrounding the roots, likely originating from the failed root canal.

Following a successful root canal, the infection in the bone should go away, having been worked on by your immune components and bone-forming cells.  Dark areas in the bone should disappear over a period of several months, showing that new bone has been created where once bone was lost to infection.

Sometimes the canals are so complex, having accessory areas that are neither visible nor accessible to the dentist, that by the fact that the dentist cannot clean and shape them, they continue to house infection that feeds into the bone.  Example:  The managing partner of our Dental Centers (a dentist; let's call him M) had a root canal done several years ago by the founding chairman of the Endodontics Department at a nearby University Department of Dentistry.  A widely respected, smart and very effective endodontist.  The root canal result was excellent, visibly and radiographically, and the tooth was fine for several years, after which M began to experience pain and swelling from the same tooth.  He went back to the same endodontist, now retired from his chairmanship and in private practice.  The endodontist remade the root canal, and M was fine for about one year, after which the booth became sore and infected once again.  I had the good fortune to extract this tooth, and upon viewing it outside the mouth, under magnification, with good lighting, we discovered a very small accessory canal running from the nerve chamber, straight down into the furcation (separation) between the roots.  This was not visible on xray, nor was it visible to the endodontist either time, even when using a 10-power endodontic microscope while doing the second procedure.  I think this example may be the best explanation of how a root canal, provided under the best of circumstances, twice, can still fail.  dd

---------- FOLLOW-UP ----------

QUESTION: Hi Dr Finnk, thanks for the information and the story. That has helped a lot.

So, I wanted to know if the root canal shows that it has filled up correctly on x-ray, and everything is fine, is retreamtment still needed? I went to my dentist, and he said my root canal is fine. He said if anything, the next step would be an apicetomy (might of spelled wrong) where there is a surgical procedure to remove the infection. However, if there was an infection prior to the root canal, and right after the root canal, the infection should go away on its own right? I even took 2 courses of amoxicillin. The thing I don't get is the fact that after the root canal it didn't hurt. Several weeks later, it started hurting again. The timing of it all is odd. So the doctor opted for stronger antibiotics such as augmentin. Is it wise to take a third course of antibiotics, with a different and stronger kind?

Answer
I believe I answered your question with my initial answer and story.  You may continue to take antibiotics.  And they may help while you take them.  But at some point, you will want some definitive treatment, so that you can stop taking antibiotics, and so that your jawbone can heal.  You can have the root canal re-treated.  You can have an apico-ectomy.  Or you can have the tooth removed, wait for the bone to heal, then consider placing an implant and crown.  All these treatments are acceptable.  As I said before, an xray may show that the root canal was done well, but there may be issues that cannot be seen on xray.  dd