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I have a tooth with a root canal that has been redone once, nine years ago. the tooth is bothering me again. Can the root canal be redone more than once?
– Jodie from Ohio
A root canal treatment can be re-done twice, three times, whatever, but that’s not the question. The question is whether or not that makes sense as a treatment.
Root canal treatment is one of the less predictable treatments in dentistry. It is accepted that even when the dentist has done everything right, there could be a failure rate of 5-15%, maybe more if the dentist is less skilled at this procedure. Let me explain the reason for this.
The living tissue inside your tooth is the pulp. There is a pulp chamber up in the crown of the tooth and a pulp canal that conducts the blood supply and the nerve to this pulp chamber. When the pulp becomes infected, the chamber and the canal have to be cleaned out and sealed against any bacteria re-entering the tooth. The problem is that the pulp canal can have branches and twists and turns inside the tooth that can, in some situations, make it difficult or even impossible to full clean out and seal. For example, in a molar, the standard number is three canals—one for each of the three roots. But often there is a small, difficult-to-find fourth canal. Furthermore, sometimes some of the canals can split off into branches at right angles. The dentist has tiny, highly flexible files that he or she inserts into the tooth and cleans out the infected tissue. There is no way this file can be manipulated to enter a side branch that comes off at a right angle.
Now these anomalies occur in a small minority of teeth, so the large majority of root canal treatments are successful. If a root canal treatment fails, re-treatment can remedy the situation, but only in somewhere around 50 to 75% of the cases. But if that re-treatment was done by a dentist skilled in root canal treatment and didn’t work, there’s a pretty slim chance that it will work if tried again.
There is another option, and that is root canal surgery. The dentist, most likely a root canal specialist, will make an opening in the bone and cut off the root tip of the infected tooth, and probably do a small filling at the end of the tooth to help ensure that it is sealed. This is called an apicoectomy and retrofill. If a root canal re-treatment has failed, this is usually the next best option and will be successful again in somewhere around 50 to 75% of the cases. Furthermore, some roots of some teeth are not surgically accessible or are in locations that would make surgery very risky, such as near the nerve that goes to the lower jaw and lip.
Another option is extraction. This isn’t the first choice, for sure, but some teeth are simply not savable.
– Dr. Hall
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