Root canal tooth hurts with pressure months later

Even when every step of the procedure goes smoothly, a tooth that is treated with a root canal may experience prolonged sensitivity or reinfection. According to the American Association of Endodontists (AAE), certain circumstances may prevent a tooth treated with a root canal from healing properly:

• If the dental professional misses tiny, hidden canals or curved canals during the first treatment, the bacteria inside them may not be entirely removed and can cause infection.
• Immediately after the root canal, the dental professional often places a temporary filling to provide a short-term seal for the root canal before placing the permanent restoration (such as a crown or filling). If there is a delay in placing the permanent restoration, there is a greater chance that the root canal can get reinfected.
• If bacteria in the saliva get under the filling material before the filling is placed, the canal can become reinfected.
• If the patient doesn't maintain proper oral hygiene, new cavities can form on the same tooth that already received a root canal.
• A filling or crown placed on the tooth that received the root canal can crack, loosen or break, allowing a new infection to start.

Q1. I recently had to have a root canal done on a tooth that the dentist had just done a crown on. This was not my first root canal, but it was extremely painful and had an infection in it. It took a while before I was pain free. Now, three months later, I am having pain in the tooth again. What could cause this?

The current pain you are experiencing in the tooth that previously had root canal therapy may be caused by the following:

1. The tooth has an extra canal that was not cleaned out and filled. This means there is an extra physical root.
2. The tooth has an accessory canal, which is a tiny piece of nerve that is rarely cleaned out and filled. These accessory canals are hard to see on X-rays but are small branches of the nerve trunk.
3. The tooth may be fractured, since root canal teeth do get dried out internally.
4. The root canal has become reinfected.

The process of performing root canal therapy is typically quite successful. Over time, however, problems can occur because the tooth no longer has internal fluids or blood supply. During root canal therapy, the tooth is cleaned out, and a rubbery material is often packed inside the canal. At any time prior to the root canal, the tooth may become fractured and go unnoticed by the dentist. A fracture or crack in a tooth may create the need for root canal therapy and the pain leading up to treatment. Once the tooth has had its root canal therapy, things may be fine for a while, but then this crack starts to trap bacteria and cause pain.

An accessory canal is a canal that is impossible to see on an X-ray, but it can leave a tiny amount of nerve tissue after a root canal is performed. These branches of the main nerve are almost impossible to fill. Oftentimes, the nerve will die, and there is no problem since it is such a small area.

There are situations in which a tooth has more roots than it is supposed to. Single-rooted teeth can have a second root, double-rooted teeth can have a third root, and multirooted teeth can have an extra root canal. Sometimes they are visible on X-rays, and sometimes they are not. A qualified root canal specialist will usually pick up this extra canal and may even find an extra third or fourth canal. There are times when even a specialist can miss these extra canals, and a few months later you feel pain from the untreated canal. I would go back to your root canal professional and see if this is the case. Sometimes the pain is just clenching and grinding on a tooth that had a root canal and no further treatment is needed except a bite adjustment. There are also other situations where the root canal can get reinfected, but these are rare.

Q2. I had a root canal treatment several years ago in my only lower molar on the left side. I then had a gum infection, and the dentist found another canal that had gotten infected. How does a dentist do another root canal in a tooth that already had one? Also, do I risk ending up with incurable periodontitis if I have a second root canal and it is unsuccessful?

— Nancy, Connecticut

It is possible to have more than one root canal treatment on a single tooth because some teeth do have two roots. The need for another root canal can occur within a few weeks of the original one or several years later. Sometimes it's hard for a general dentist or endodontist (one who specializes in root canal treatment) to find every canal. A canal can sometimes be calcified or closed off or is simply not obvious on an X ray or during endodontic therapy.

Undergoing a second root canal is perfectly fine and does not mean your tooth will be lost. Hopefully, the second root canal will take care of the extra root, and your condition should improve.

Obviously, the quality of the work, as well as your oral hygiene and cleanings, is important for preserving your teeth over the long term. You don't risk incurable periodontitis if there is only a root canal or nerve-dying phenomenon going on. If you also have periodontal disease, however, then that needs to be taken care of by your dentist or periodontist as well.

On completion of the second root canal, hopefully your endodontist will evaluate your situation and pronounce the tooth healthy. He or she will also let you know if there are any other problems associated with this tooth — periodontal disease, decay, or fracture, among others.

Q3. I had a root canal treatment several years ago in my only lower molar on the left side. I then had a gum infection, and the dentist found another canal that had gotten infected. How does a dentist do another root canal in a tooth that already had one? Also, do I risk ending up with incurable periodontitis if I have a second root canal and it is unsuccessful?

— Nancy, Connecticut

It is possible to have more than one root canal treatment on a single tooth because some teeth do have two roots. The need for another root canal can occur within a few weeks of the original one or several years later. Sometimes it's hard for a general dentist or endodontist (one who specializes in root canal treatment) to find every canal. A canal can sometimes be calcified or closed off or is simply not obvious on an X ray or during endodontic therapy.

Undergoing a second root canal is perfectly fine and does not mean your tooth will be lost. Hopefully, the second root canal will take care of the extra root, and your condition should improve.

Obviously, the quality of the work, as well as your oral hygiene and cleanings, is important for preserving your teeth over the long term. You don't risk incurable periodontitis if there is only a root canal or nerve-dying phenomenon going on. If you also have periodontal disease, however, then that needs to be taken care of by your dentist or periodontist as well.

On completion of the second root canal, hopefully your endodontist will evaluate your situation and pronounce the tooth healthy. He or she will also let you know if there are any other problems associated with this tooth — periodontal disease, decay, or fracture, among others.

Q4. Recently my son, at age 26, was told he has resorption in one tooth. He did have braces. What are some options and exactly what causes it?

The cause of root absorption is still unknown, but essentially, this is when the apex, or the top of the root of teeth in bone, starts to melt away. A possible cause is heavy force over a short period of time, as can be seen with braces and other orthodontic therapies. It is impossible to know in advance whether root resorption will take place, but the majority of patients who go through orthodontic therapy do not get root resorption.

Many teeth with root resorption still function properly and are fine to keep. Your dentist must evaluate each tooth on an individual basis via X-rays and any movability of the tooth. A tooth can last for many years or even a lifetime despite resorption. If the tooth is solid, I generally leave it alone. If the tooth that has root resorption needs to be a part of a fixed bridge, then your dentist must analyze whether it is strong enough to act as a bridge support. Ultimately, this judgment must be made on an individual basis.

Q5. I took my daughter to a dental practice in Chicago in 2003. They told me that she needed lots of work done — at least five root canals, four wisdom teeth pulled, and three fillings. I couldn't believe it. They told me they could do all the work. Later, after the last root canal, they decided not to finish the job. I took her to another dentist, who told me the root canals that were done were not done correctly. Now, according to this dentist, she will have to get all the teeth removed. What can I do? My daughter is 20 years old with low self-esteem and terrified of going back to the dentist after this ordeal.

— Sharon, Illinois

I think it is critical that you see a very competent general dentist whom you trust and who will do a complete medical and dental evaluation of your daughter's mouth including X-rays, charting, medical history, and dental history. The American Dental Association can give you a recommendation for an excellent dentist in your area. Another option would be to visit a dental school or a hospital-based dental program.

Based on the information you and your daughter can provide, the dentist needs to come up with a diagnosis and treatment plan. The quality of the root canals and fillings can easily be evaluated by either a regular general dentist or a specialist in endodontics. It is critical that you have a clear understanding of both what is wrong and what steps are going to be taken to treat the problem before anything further is performed on your daughter. If the diagnosis is explained properly and the treatment is performed by a caring, gentle dentist, then there is no reason for your daughter to have low self esteem and she can get back on the road to recovery.

Learn more in the Everyday Health Dental Health Center.

The Latest in Dental Health

Are You Holding Your Toothbrush Wrong? Should You Floss or Rinse?

Many people never learned the basics of brushing their teeth. Here’s how to correctly preserve your pearly whites.

By Susan K. TreimanNovember 30, 2022

Byte Invisible Braces Review 2022

Byte clear aligners are a more affordable option for correcting mild to moderate dental issues at home than Invisalign or metal braces. Treatment with...

By Will CarterSeptember 8, 2022

Are You Grinding Your Teeth? Here’s How to Know and How to Stop This Harmful Habit

Extreme tooth grinding may shatter teeth, destroy dental work, trigger jaw pain and morning headaches, and provoke nagging from sleep partners addled ...

By Susan K. TreimanAugust 18, 2022

SmileDirectClub 2022 Review: Can This Clear Aligner Brand Improve Your Smile for Less?

Are you considering at-home clear aligner kits? Before buying, check out our SmileDirectClub review, including the pros and cons, costs, and treatment...

By Will CarterJuly 15, 2022

Are You Brushing Your Teeth Too Hard?

Brushing your teeth incorrectly can lead to problems like tooth sensitivity and enamel wear. Here’s the right way to do it.

By Lisa HaneyJuly 11, 2022

6 Best Affordable Invisible Braces Brands of 2022

Looking for the most affordable way to straighten your teeth? Read our detailed review of the top affordable invisible braces brands to compare prices...

By Will CarterJune 23, 2022

Read Our Reviews of the Best Invisible Braces in 2022

Invisible aligners are a teeth-straightening alternative to traditional metal braces that could save you money and time. Find out which brands offer the...

By Erica Anand, DDSMay 11, 2022

Does Invisalign Really Work?

Is Invisalign worth the hype? Will it work for your teeth-straightening needs? Learn more about the treatment plan, cost, pros, and cons of Invisalign...

By Hannah SherkSeptember 13, 2021

Invisalign vs. Braces: Which Is Better?

When you compare Invisalign and traditional braces, which teeth-straightening option is better? Learn more about the benefits of both, how the treatment...

By Nicole GleichmannSeptember 9, 2021