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What are the Symptoms of a Bad Root Canal?

By T. Alaine
Updated Mar 03, 2024
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The symptoms of a bad root canal depend, to at least a certain extent, on why the procedure went off course, but some of the most common include pain extending past the normal healing period; inflammation and swelling of the teeth, jaw, and face; and infection. Gum sensitivity and teeth that become fragile or brittle may also be signs of trouble. Root canals are generally considered “routine” dental procedures, but people who suspect that something has gone wrong are usually wise to get treatment, or at least a second opinion, before waiting too long. In most cases, the faster bad procedures are identified the more likely it is that they can be fixed.

Extreme Pain

For most people the first recognizable symptom of a bad root canal is pain, though it’s important to note that some pain is normal after even a perfect root canal. The procedure is invasive and patients often experience discomfort for a week or more. Pain is only usually a problem when it doesn’t go away or gets worse. When the pain is very severe or lasts longer than the dentist or oral surgeon anticipates, it may be a sign that there’s a problem.

At first, the pain might be negligible or difficult to notice. For some people it is isolated to the region of the tooth in question, but it also has the potential to be very intense, most often a throbbing pain felt all over the head. A lot of this has to do with exactly why the procedure went bad. Sometimes surgeons don’t get all of the root, leaving some decayed bits deep in the gum; other times, the impacted tooth has been improperly sealed or capped. The pain a person feels is usually in proportion to how badly things were botched, or at least how close mistakes were to major nerve endings.

Swelling and Inflammation

People may also experience swelling in their jaws, gums, and even faces. In most cases this is a result of tissue inflammation in or around the impacted area. Inflammation happens when the body’s blood vessels and tissues expand and try to force out damaged cells, which typically causes swelling. Patients suffering from dental inflammation commonly complain of pressure and heat in the mouth along with swelling and pain. Most of the time skin that is inflamed looks red and “angry,” though it can be hard to see this in the mouth.


Infection is the probably the most serious symptom of a bad root canal, and in most cases it will not go away on its own. Bacterial strains cause infection by entering into the body and multiplying. There are a couple of different ways this can happen during a root canal, but the most common is remnants of tooth material or nerves that should have been removed but weren’t; when these bits and pieces are no longer attached to functioning teeth, they can begin to decompose. When this happens within the gum bed, infection almost always results.

A dentist who fails to sterilize equipment or who otherwise introduces germs to the site can put a person at risk of infection, and harmful bacteria can also come in during healing if the tooth hasn’t been sealed properly. Infections usually start locally, but unless they are treated — usually with antibiotics — they can spread and, in rare cases, may actually be life-threatening.

Gum Sensitivity

Intense, long-lasting sensitivity in the gums may also be a symptom. As is true with pain, some degree of sensitivity is normal and should be expected; the condition becomes concerning, though, if it just doesn’t go away or if it arises weeks or months after most other healing has finished. Late-onset gum sensitivity is sometimes a sign of nerve damage.

Tooth Fragility and Brittleness

It is sometimes the case that inflammation or infection is so minor at first that it all but escapes a person’s notice. Teeth that are riddled with infection and decay typically become very fragile and brittle over time, though, which means they will break and chip more easily. These symptoms may not manifest until months or even years after the original procedure.

When to Get Help

Most dentists and oral surgeons advise their patients to come in for an evaluation any time they experience intense pain or swelling after getting a root canal. Patients who are running a fever shortly after the procedure should also usually get checked out, since fever is often an early sign of infection. The earlier a bad root canal is recognized, the easier it usually is to fix.

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Discussion Comments
By anon353178 — On Oct 28, 2013

All of you who said you haven't had a root canal gone bad may not have waited long enough. I have had two root canals go bad, but the infection built so slowly that it was years before anyone discovered them. In both cases, the dentist didn't go all the way to the ends of the canals.

Just today I had an endodontist try to correct one of them but he couldn't, so it was $395 down the drain for him trying. He wants to attempt to correct the second one but that will also cost $395 if it doesn't work. I'm just going to get them extracted.

By anon337421 — On Jun 05, 2013

Always, always go to an Endodontist for a root canal and not your dentist. An Endodontist specializes in root canals. I went to an Endodontist for a root canal, which was done over three visits without a glitch, whereas my husband just had his root canal done by our dentist and has a massive infection in which he's lost feeling in part of his face. He started antibiotics yesterday, but it still seems to be getting worse.

By anon333117 — On May 03, 2013

Here is the solution: Use antibiotics if the pain intensifies because that means infection has set in.

Take Betamox 500 mg capsules 15 (057054)S4. Take one, three times a day and complete the course for five days. The results are astounding. From day one, the pain is relieved if not removed as it attacks the infection.

Be sure to drink plenty of orange juice and eat bananas during the process until you can nibble on some chicken pieces, mashed potato and rice!

By anon316888 — On Jan 31, 2013

I had a temporary filling after root canal. I chewed bread on that side of my mouth accidentally and had a wave of pain. I'm afraid of infection. I took an NSAID.

By anon288835 — On Aug 31, 2012

A bad root canal is awful. I have a cyst above the two teeth before you get to the molar and had a root canal. I have had to see an oral surgeon. I will be having surgery to remove they cyst along with losing the tooth that had a root canal. I also have bone loss and will have to have some bone grafts.

If the blood flow has been cut off long enough to the tissue around the cyst the grafts may not take. Plus if any infection or problems crop up, I could lose all three teeth! So now, I'm going to have to have an implant done or bridge once the healing has taken place.

By SarahSon — On Dec 24, 2011

Fortunately I have never had to have a root canal, but I have heard a lot of bad stories.

I am just wondering if they are any kind of natural root canal alternatives? If the main reason someone has to have a root canal is because of infection, I would think there would be another of way of treating it.

Does anyone know if they are any alternatives like this instead of going through a root canal? Of course if you are in a lot of pain, it would have to be something that worked pretty quickly.

By sunshined — On Dec 23, 2011

The pain I was having in my mouth and jaw before I had my root canal was some of the most intense pain I have ever had.

I was about 2 hours away from home at a conference for work when the pain intensified. I was not able to get into my dentist until the next day.

What I thought would be an pretty easy fix, ended up being a root canal gone bad. At first I just thought it was normal discomfort that went along with the recovery process.

Come to find out the seal over my tooth was not completely sealed, and I ended up getting an infection. This pain and discomfort was even worse than what I had before my root canal.

My dentist ended up fixing it and didn't charge me the second time around. After all that, I never want to go through another root canal procedure again.

By sunnySkys — On Dec 23, 2011

I'm glad to know that root canal complications aren't that common. However, if it happens to you, that's no consolation!

A good friend of mine actually had a bad root canal, and what she went through was awful! She had a lot of symptoms the article described, including throbbing pain all over her head. She also ended up with a pretty nasty infection.

It took her a few days to realize she wasn't having normal root canal symptoms, and then she headed back to the dentist and they were able to fix the problem. The whole thing was still pretty scary though!

By JessicaLynn — On Dec 22, 2011

@Monika - I agree with you-root canals are pretty unpleasant all around. And the root canal cost is usually staggering! You have to usually pay over a thousand dollars to go through that torture!

But anyway, I just wanted to say that dental infections, which can happen after a bad root canal, can be really serious. I know most people don't think that something happening to their teeth can kill them, but it totally can!

I read a really disturbing article awhile ago about a guy on the west coast who actually passed away from a dental infection. He didn't have insurance and didn't have the money to get treated. Horrible!

By Monika — On Dec 21, 2011

I've had a root canal procedure (actually I've had several -- I have really bad teeth), but luckily I've never gotten a "bad" root canal. Getting a well done root canal is bad enough, I can't imagine having problems after the fact!

I do want to reiterate what the article said though-some pain is normal after a root canal. After the last root canal I had, I was in pretty serious pain for about a week. However, every day it got a little bit better, and I was able to control it with pain relievers.

From what my dentist told me, if the pain doesn't at least start getting better after a few days, you should high tail it back to the dentist!

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