Having both radiographs and a cone beam at my disposal is a priority for me. But sometimes, even these two tools don’t show the whole picture. Today, I want to share a tooth story about a woman whose tooth with a previous root canal hurt with pressure months later, and why I needed more information than imaging alone could provide.

People always say “Don’t judge a book by its cover.” To that, I always say, “Don’t judge a tooth by its x-ray.”  Also, don’t assume the worst. Give teeth a chance.

That’s how I practice endodontics. I never say “never,” and I always try to save teeth when it’s even remotely possible. I won’t know if something is going to work until I try. Let’s look at a specific case that highlights the need for both tools!

Patient: 35-year-old woman with pain in a tooth that had already had a root canal

Diagnosis: Previously Treated and Symptomatic Apical Periodontitis

My Patient Had a Tooth with a Previous Root Canal that Hurt With Pressure Months Later

This patient came to me as an emergency case, experiencing lots of pressure and pain on a tooth that had already had a root canal. Usually, I try not to “meet and treat” my patients, because I need time with them. 

I use that time to answer their questions, make a solid diagnosis, ensure I’m treating the right tooth, and feel confident that the patient understands their treatment options and their upcoming treatment plan.

Getting the patient to understand the why is key, and that takes communication, transparency, and patience. I’m all about the why, because when a patient understands that, they become empowered in their own care.

However, if the patient’s pain is characterized by intense pressure, and they are in tears, I reassess the situation and treat it immediately. I know that their tooth is trying to drain, and I want to make that happen for them, so they can get out of pain.  

When a patient comes to me, and their tooth already had a root canal, my protocol is to take not just x-rays but a cone beam as well. In my practice, radiographs and CBCT go hand-in-hand, like PB&J.

x-rays and a cone beam radiograph 1
x-rays and a cone beam 2nd radiograph

x-rays and a cone beam 3rd radiograph

x-rays and a cone beam 4th radio

x-rays and a cone beam 5th radio

Different Pictures: X-Rays and Cone Beams

Some dental professionals would have said that the cone beam was suggestive of a vertical root fracture. In fact, it was most definitely a part of my differential diagnosis. But I could not be certain by looking at the cone beam alone.  

The x-ray imaging looked like the previous root canal had been done well. But since I had no history of the tooth—and the patient didn’t remember any details—I had to keep in mind that it was possible that the tooth had a new bacterial infection that had nothing to do with a crack. 

It can be easy to blame pain and infections on cracks when treatment isn’t working, but bacteria is a more likely culprit.

There are so many variables I did not know about the initial treatment. Was a rubber dam used? Was full-strength sodium hypochlorite used? How long did it take the patient to get her crown?

I gave the patient her treatment options: retreatment with another root canal, or extraction with an implant. I explained to her that, even if she chose a second root canal, I could find a fracture in the tooth and it would still need to be extracted. She wanted me to try it anyway. 

Complete transparency before starting procedures is extremely important to me and to my patients. 

What I found surprised me. I opened the tooth to find black, black, and black. I was so surprised to see the level of infection in the tooth. The gutta percha was so contaminated by infection that it turned black.

tooth had bacteria

Once I removed the gutta percha, the infection started to drain.  And THIS is the key to helping a patient feel better. Instant gratification for both me and my patient. That pain to pressure she was feeling months later after her previous root canal was finally gone.

Making an Informed Decision

Look, I understand that there’s a learning curve to reading cone beam images, and they can definitely be misinterpreted. So can radiographs! Some would have thought to take this tooth out because of a possible fracture (since a root fracture can cause pain after a root canal). But that’s all the more reason to explore further.

If you’re not 100% definitive about the cause of root canal failure, then access the tooth for a visual assessment to be sure. Sometimes we don’t know the answer before going into the tooth. But if you prepare your patient for the potential outcomes, then you have given them the option to take the chance with you. 

Thankfully, I had both the x-ray and the cone beam images to help inform me. Every tool and process plays an important role, and the more you stick to your gut, get great experience, and evaluate the different options, the better chance you have of saving teeth. That said, don’t forget the “sticking to your gut” part (which comes from practice, practice, practice), because your tools may not always show you everything.

The cone beam for this patient did not look good, but if I had judged the tooth by its x-ray, I would have done a total disservice to this patient. It would’ve been a complete misdiagnosis, because the root canal infection didn’t show up on the x-ray. 

I was lucky that the patient wanted to try and save the tooth. It was the right choice for her and her health.

final radiograph result

There’s a Lot to Take Away from This Case of a Patient Whose Tooth with a Previous Root Canal Hurt With Pressure Months Later.

One of the main lessons I hope you take away from this tooth story is to always be transparent with your patients. Give them all their options, and the “why” behind each option. 

Also, if you rely solely on an x-ray to diagnose, you can make the wrong choice. Use all the information and clues you have. 

Remember, a tooth can be contaminated, yet that won’t show up on x-rays or a cone beam. (In fact, I would recommend you assume that it’s contaminated over just trusting what the images say.) Be open to stepping outside your standard operating procedure if it allows you to better serve a patient… especially one who is in pain.

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– Sonia