While all is not equal with x-rays and a cone beam, having both tools available is a priority for me. However, sometimes, even these tools don’t show the whole picture. Why? 

Well, people always say “Don’t judge a book by it’s cover.”

I always say, “Don’t judge a tooth by its x-ray.”  Also, don’t assume the worst. Give things a chance.

That’s how I practice endodontics. I never say “never,” and I always give teeth a chance. 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


X-Rays and a Cone Beam: I Do Both

My philosophy served a recent patient well. She 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 — they have questions that I want to answer. I like to make sure the patient understands their treatment and treatment options, and I want to make sure I am treating the right tooth. 

Getting the patient to understand the why is key, and that takes communication, transparency, and patience.

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

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. (Now do you see why x-rays and a CBCT go hand-in-hand? Or at least in MY practice, they do!)

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…  and that was possible (and most definitely a part of my differential diagnosis). But I could not be certain.  

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.

So Many Unknowns

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. 

When X-Rays and a Cone Beam Aren’t Enough

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. 

An Informed Decision

I understand that there’s a learning curve to reading cone beam images, and they can be misinterpreted. Some would have thought to take this tooth out because of a possible fracture (since root fracture can cause pain after a root canal).

If you’re not 100% definitive in 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 and evaluate the different options, the better chance you have of saving teeth. (That said, don’t forget the “sticking to your gut” part, because your tools may not always show you everything.) 

X-Rays and a Cone Beam Image: Each a Part to Play

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. 

In Conclusion

Always be transparent with your patients. Give them all their options — and the “why” behind each option. 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 and 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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final radiograph result