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Dentistry/Pain after root canal


QUESTION: I had to have a root canal on a front tooth re-done a week ago as there was a small amount of shadow on an x-ray at the top of the root.  I had been experiencing some discomfort on bite which may have indicated an infection, but this had improved somewhat leading up to the re-treatment.  I had however been experiencing a sort of nerve pain in my gum on the left upper side, almost like a sore feeling across two or three teeth between the front and back - but the gums themselves and the teeth were not swollen or red.  I had this sensation a number of times leading up to the re root canal treatment which usually lasted a day or so but had calmed down a couple of weeks prior to the procedure.  Within 48 hours of the re-root canal treatment I now have this sensation back, not directly over the front tooth, but along the top of the gums in between the front and back on the same side.  It does not respond to painkillers.  My endodontist had asked me to call my dentist if I was experiencing any pain after the treatment, as he is now on holiday until my next appointment for stage 2 of the treatment in about 2 weeks - he felt I may need some antibiotics.  My question is please can you advise if you are aware of what this nerve type of pain - why I may have had it prior to treatment and why it has re-appeared again - and would antibiotics help in this situation?  Thank you.

ANSWER: Hi Jenny,

I'm sorry you're having all this go on. It's hard for me to give you absolute accurate answers without being able to exam you and see your X-rays, but we do see this type of thing fairly frequently in my office, so I'll tell you what I THINK might be going on.

When you have a root canal re-done because there is a shadow at the end of the tooth, that means the original root canal has failed. The shadow is an area where the bone has not healed due to some problem within the tooth. When the new root canal is done, the equilibrium that has been established in the bone is altered and your body now starts to heal the area again. This healing is often associated with pain and sometimes swelling. The most common treatment at this point is to start on antibiotics, so I would definitely suggest that you call your dentist and get a prescription ASAP. It will take 24-48 hours for the antibiotics to START working. You might also need a stronger pain medication if what you are taking is not helping.

I hope this explains things for you.

Gary Backlund DMD, MSD

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QUESTION: Thank you for your advice.  I think your answer has identified to me what is most likely going on with regard to the discomfort I have been feeling which has built up over the last few days since the treatment.

I would like a little more advice please regarding the antibiotics.  I was able to speak with my endodontist today on the telephone and he has prescribed me some antibiotics just in case I need them, but has told me not to take them unless absolutely necessary - either severe swelling or severe pain over the next 2 weeks whilst awaiting the second stage appointment.  He asked if the area around the tooth was swollen or red, which it is not. So I am therefore confused as to whether I should take them or not based upon your response saying I should take some asap.  The discomfort has subsided a little - it has now been 4 days since the treatment - but your answer as to what is now going on regarding the bone healing has I think answered this.  What I am feeling is more of a niggling discomfort level and a heavy feeling rather than throbbing or severe pain.  However you do read on the internet that bacteria from the root canal can spread to the body causing problems which gives me concern and therefore making me feel the need to take the antibiotics - so confused!!!!

Thank you

ANSWER: Hi again Jenny,

You previously told me that pain medication was not helping with the pain. If that is the situation, then that would fit one of the criteria your endodontist gave you for starting the antibiotics. We try not to overuse antibiotics, so your endodontist is just being cautious, however, when you can't control the pain then you need extra help. Your current question says that you are not in severe pain, so maybe you are getting better. So really, it's your call. If you feel like you are truly improving, then give it another day or two. If you are still having a lot of discomfort and it's affecting your daily life, then start on the antibiotics. Taking them is not really a BIG deal, just don't take them unless you need them. I know that can be confusing, but none of us are dealing with what you are feeling, so you need to make the decision.

As for a root canal infection spreading to other parts of the body, it's a pretty popular concept, but we really don't see that in clinical's pretty much "an old wives tail" so don't let that affect your decision.

Hope this helps with your decision.

Gary Backlund DMD, MSD

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QUESTION: Thank you so much for you reply.  Today is day 5 and the discomfort is now just centred around the root of the tooth feeling a little tender if you press it and just a heavy feeling, but nothing major, just you know it is there all the time.  I will therefore take your advice and hold off the antibiotics unless I feel I absolutely need them.

You mentioned that the discomfort was probably due to the small shadowed area of bone loss that was showing on the x-ray now starting to hopefully regenerate - is this rather like a broken bone healing? and the associated pain you would get in that instance.  I suppose my real question is how long would I expect to have this type of discomfort.  Also will this be compromised again when the endodontist opens up the root in a couple of weeks to clean it out again?  Sorry for all my questions but your professional responses really do answer all my questions so well and are very informative.  Thank you

Hi Jenny,

It's really impossible to tell you how long all this will go on. Everyone heals at different rates and the infection/irritation is different in everyone also. As a general rule, anywhere from a few days to a couple weeks for things to be absolutely normal.

Also, whether you have this happen after your next appointment has a lot of variables also...what needs to be done to the tooth, your resistance to any flare up, whether there will be a flare up, what the situation is at the end of the tooth to name a few. Unfortunately, you don't have much choice at this need the root canal finished, so whatever happens, you'll just need to be ready to deal with it with the help of your endodontist.

Wish I could give you better answers, but that's pretty much the situation. Things just aren't predictable when you're dealing with the human body.

Gary Backlund DMD, MSD


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Gary Backlund, DMD, MSD


I am an Endodontist ( root canal specialist ) and can answer questions about root canals and their treatment. I cannot diagnose or treat online, but can answer general questions. I have been a specialist for 25 years and am Past President of the Washington State Association of Endodontists.


25 years practicing as a specialist

American Association of Endodonists, Past President Washington State Association of Endodontists.

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