I’m a sucker for a good tooth story. Over the years, I’ve noticed that one kind of tooth story tends to repeat itself pretty frequently and that’s the stories that really illuminate the advantages and disadvantages of the CBCT in your root canals.

There’s one kind of story I’m thinking of in particular and it’s the kind I like to refer to as “The Weekender.” I’ll explain …  

The advantages and disadvantages of the CBCT when it comes to “Weekender” cases

You might be familiar with these frustrating cases in your own practice. 

I’m talking about the patient who had severe, out-of-their-mind tooth pain over the weekend. They took every pill in their medicine cabinet, but nothing helped. They left messages on your office phone begging you to help them or prescribe them antibiotics.

Then they finally get in your chair on Monday morning… and their tooth is feeling much better.

Any of that sound familiar?

Here’s where we can look to our CBCT imaging. The advantages become clear as we uncover the culprit. And when it comes to the cone beam, we have some of the usual drawbacks, too,  which never outweigh the advantages, in my opinion.

The Real Culprit: A Dying Nerve

You might assume that the patient took an antibiotic and that did the trick, but it’s important to realize that the true villain of The Weekender story is a dying nerve. The process usually causes such unbearable pain that nothing alleviates the symptoms. However, once the nerve is dead, the tooth starts to feel better.

If you pay close enough attention to your patient’s tooth stories, you’ll start to notice this pattern: First, a tooth becomes sensitive to cold, then to heat, and finally to percussion—the typical progression of tooth pain. 

Once a patient experiences pain from heat, you know the nerve is dying (this is also the time when they might have referred pain, and might think that a different tooth is the one causing all their problems). Once the patient notices pain from percussion, they’ll be able to localize the pain, and, since the nerve is at this point already dead or close to it, their pain level will drop.

So, if the patient reports that their pain is under control, it’s not necessarily because an antibiotic worked—it’s more likely that the nerve in the tooth died.

To make the correct diagnosis, you’ll need to make sure to do your due diligence when it comes to diagnostic tests, which can also mean whipping out the CBCT (with all its advantages and disadvantages, too, like false positives that are actually artifacts, yikes!). 

You’ll probably be looking for a tooth that is necrotic, doesn’t respond to cold, has sensation to percussion (even if it’s only slight), or shows symptoms of apical periodontitis.

Note that it’s possible for you to make one diagnosis, only to have your patient get a whole other diagnosis once they see a specialist—the situation can change quickly, which adds a layer of challenge to diagnosing these cases.

Now it’s time for a tooth story …

This patient experienced horrible pain for a few days, was put on Ibuprofen, Hydrocodone, and Amoxicillin, and then her pain went away. By the time she got to my office for her evaluation, she was feeling dandy and pain free. 

It makes sense, right? I mean, it’s pretty difficult to figure out what the problem is when it’s covered up with all these medications. However, knowing that this is a very common tooth story, I really had to investigate and use all of the tools in my toolbox. And when I have a diagnostic question, I always resort to my cone beam as step one to see if it will give me any more clues into this tooth story.

The advantages of using CBCT include its facilitation of diagnosis—especially early on in the detection of disease, as well as helping me get a handle on etiology and determining true lesion size. 

At the time of this particular evaluation, these were the results of my diagnostic tests: All of the probings were within normal limits, and there was no pain to percussion in the quadrant. Tooth #2 felt cold, but teeth #3-5 had no response to cold.

Just remember: normal can be subjective

Now, It’s really important that you understand what is “normal” and the best applications for CBCT (and some of the advantages and a disadvantage), so you can apply all this to your patient’s unique situation. 

Since some people don’t feel cold on their premolars, we shouldn’t assume that all three of those teeth were necrotic. It’s always a good idea to find a similar tooth under similar conditions (in this case, another first molar with a crown on it) and to see how it responds to cold—just make sure that that tooth hasn’t been root canaled before. If that tooth responds to cold, then the other first molars should also respond to cold, and you’ll know that the crown is not getting in the way of your test.

The periapical radiograph didn’t reveal much. The sinus was superimposed over the apices and so it was difficult to see if there was any endodontic pathology in the area.

The bitewing showed that there were no opposing teeth, so I quickly disregarded the possibility of referred pain from the mandible.

Before we go deeper, there are a couple of CBCT disadvantages

I keep talking about how awesome my CBCT is, but before we keep moving into this tooth story, there are a few things to look out for when it comes to disadvantages. (Or, at least, quirks to be aware of.)

First, investing in CBCT is NOT cheap. Plus, it has a steep learning curve. This isn’t one of those get-it-and-use-it-like-a-pro-tomorrow types of imaging tools. (Fortunately, I teach you some great CBCT tips in E-School, my CE course for general dentists.)

Second, it is possible to get false positives from artifacts. Don’t assume your CBCT is going to show you all the cracks in your patients’ teeth! So stay vigilant, do your pulpal and periapical diagnosis every time, and use all the other imaging at your disposal.

Third, your CBCT is super-powerful with its 3D imaging capabilities, but it can only give you a snapshot in time. So don’t extrapolate too far or misinterpret the data from your CBCT. Use your critical thinking skills!

Okay, back to the tooth story.

Three cheers for the advantages of CBCT!

The CBCT allowed me to see the bone immediately adjacent to the roots, to check if there was any periapical pathology.

One of the biggest advantages of my CBCT is that it shows me these incipient periapical radiolucencies very clearly, which means I don’t have to make the patient wait for another flareup in order to make a diagnosis and to perform treatment at a later date.

This sagittal slice showed a small lesion on the disto-buccal root.

In the axial view, you can see a lesion on the disto-buccal root and the palatal root.

And this is another sagittal view that shows the lesion of the palatal root.

And here is the final root canal.

Like I said, the advantages of using CBCT versus the disadvantages pretty squarely makes the CBCT a miracle tool. Little things like limited contrast resolution and low grade radiation are pretty minor drawbacks when you consider the cone beam can facilitate cases like this one! 

The Takeaway

The next time a patient calls you in terrible pain over the weekend, only to have the pain gone by Monday, don’t assume the problem is gone!

Proper diagnosis is such an important component of endodontics, and using a cone beam can make it easier than you might think—just one of the many advantages of CBCT. If you pay close attention, you’ll soon pick up on trends like the one in this tooth story of The Weekender and the Dying Nerve. It will make your life easier, and your patients will love you for it! 

Want some extra help with diagnosis? Check out  E-School: Everyday Endo Made Easy. I promise you’ll get insights that take your diagnostic tools to the next level.

– Sonia