Your Complete Guide to Cone Beam CT Benefits and Limitations

Table of Contents

I will never forget the day I was first introduced to cone beam technology. I was at an endodontic conference in 2009, and as soon as I saw what this advanced dental imaging could do, I was completely. blown away. 

Having been a practicing endodontist for a year at that point, I had already witnessed the struggles and the limitations of my profession. There was so much I didn’t know about my cases and so many issues I couldn’t detect on a daily basis. With questionable diagnoses and variable tooth anatomy, there was a lot of room for uncertainty throughout my procedures—and if there’s one thing I don’t like, it’s uncertainty when it comes to my patients’ cases! 

So when I saw the data presented by the cone beam, my jaw dropped to the floor. The machine allowed me to see details to an extent I had never thought possible. It was like becoming Superwoman! And after investing in a cone beam unit for my own practice in 2012, I found myself wondering how I had ever performed a root canal without it. 

Yet even with its transformative power, a CBCT isn’t perfect. Every piece of endodontic technology has its limitations, and finding your groove with it can take some time; it’s definitely not a plug-and-play machine! That’s why today, I want to provide you with a thorough guide to both the benefits and disadvantages of cone beam technology. With a well-rounded perspective of what it can do—and what it can’t—I hope to equip you with the confidence to start using this tooth-saving, life-changing tool in your own practice!

The Top Cone Beam CT Benefits

Cone beam technology is hands down the best thing that ever happened to my endo and practice, and for good reason. With incredible precision, it allows you to visualize the inside of a tooth to a level of detail you could otherwise only get by opening it up. This leads to a wide array of advantages relating to diagnosis, treatment, follow-ups, and more! Let’s explore each of the benefits in detail.

1. It Facilitates Early Diagnosis and Detection of Disease

How many times has a patient arrived at your office with pain, yet your radiograph tells you nothing—and they can’t determine which tooth is hurting them? Unfortunately, this is the nature of radiographs. We need a certain amount of cortical bone to break down before a periapical radiolucency will ever show up on an X-ray. Add some referred pain to the mix, and you really have a diagnostic dilemma! It’s a situation that no dentist likes being in, and it’s one that plagued me for years.

That is… until I invested in 3D dental imaging! Using a cone beam means I no longer have to wait for bony breakdown of the cortical plate to occur. Instead, I can see right through that buccal bone and view the bone immediately adjacent to the root. With the CBCT on my side, the guessing game is officially over. Rather than make my patient wait for the symptoms to get worse before I treat, I can treat immediately—and I no longer have to face that horrible feeling of not being able to help my patients as quickly as possible.

A Lightening-Fast Diagnosis

Let’s take a look at an example to see just how helpful a CBCT is for endodontists like me when it comes to making a quick diagnosis:

Figure 1 is a PA of a 56-year-old woman who saw her general dentist due to some pain she was having. Due to her level of suffering, her dentist recommended antibiotics, ibuprofen, and hydrocodone. Of course, that meant that by the time she got to me, she had absolutely no pain, but when I did my pulpal and periapical tests, only tooth #2 (out of #2 – #5) had a response to cold. So, I could not assume that all of her teeth were necrotic. 

At that point, I decided to take a cone beam to see if I could find any evidence of pathology. I scrolled through the entire volume of the cone beam in every plane, slice by slice, looking for any irregularities in the teeth and any resorption of bone. The entire scan looked fine… until I got to the disto-buccal and palatal roots of tooth #3, where I could see a very small radiolucency around these roots (shown in Fig. 2-4 yellow arrows). The sinus membrane was thickened around the area (Fig. 4 green arrows), as well. This was a sure sign that tooth #3 was necrotic, and I could be confident in my diagnosis—meaning my patient wouldn’t have to wait for the pain to return before receiving treatment!

This case is a perfect example of one of the many cone beam CT benefits: helping to diagnose disease when traditional testing and imaging are inconclusive. The patient’s story of having a painful episode was a tell-tale sign that a nerve somewhere had died, and it was through my cone beam that I was able to diagnose appropriately.

2. It Reveals the True Etiology of Root Canal Failure

When I see a root canal that’s failing, I always want to know why. Fortunately, my cone beam is always able to tell me the whole story! Fig. 5 is an example of a patient with a failed root canal on tooth #19.

The tooth has that typical J-shaped radiolucency around the distal root, and many would consider it fractured. But the axial slice of the CBCT (Fig. 6) shows the roadmap of the tooth, and you can clearly see a missed disto-lingual canal. The missed canal is the true etiology of failure. In reality, there’s still bacteria in the tooth, and the tooth is NOT fractured.

In Fig. 8, you see how the tooth should really look when it’s obturated. The two cardinal rules of root canal therapy were applied—finding all the canals and getting to the end of every one, and two years later (Fig. 9), you can see on the radiograph that the bone is filling back in.

This bone regeneration can also be seen in the cone beam images (Fig. 10 and Fig. 11).

With this level of cone beam scan accuracy, there’s no more need for guessing. And once you have a clear diagnosis, you know exactly what to fix, and you can heal the tooth. This case is a great example of why you should NEVER assume a tooth is cracked and send it for extraction; it might not be cracked at all. So don’t give up, and use your CBCT to your advantage!

3. It Aids in Patient Communication and Education

Sometimes I see patients who have undergone an attempted root canal, but because I have incomplete records or info, I don’t immediately know what’s going on and how to help them. That’s where advanced dental imaging like CBCT comes in handy! It fills in the rest of the tooth story and shapes my conversation with the patient. 

Here’s an example of what I mean. Fig. 12 is a radiograph of a patient who continued to have a sinus tract after she had an attempted root canal. From the radiograph, it looks like there was a previous access of a tooth with a very calcified canal. There’s also the presence of a periapical radiolucency, which is the origin of the sinus tract.

To figure out exactly what the previous clinician did, though, I needed more. So, like an endo Sherlock Holmes, I used my cone beam! In this case, the diagnostic precision of the 3D scan (Fig. 13) showed that there’s actually a canal, and so I could be confident when accessing the tooth, as long as I used the composite as my buccal border. (If I came into contact with the composite, I’d have known I was too far buccal and would run the risk of perforating the tooth.) This image completely changed the conversation I had with my patient, allowed me to de-emphasize the possibility of surgery, and gave me the confidence to try to save the tooth—the result of which you can see in Fig. 14.

4. It Helps Determine True Lesion Size

The periapical radiolucency will always be bigger in the CBCT than in the traditional PA, but don’t let size scare you—otherwise, you’ll never save teeth once you start working with a CBCT! Let me show you what I mean.

Fig. 15 is a radiograph of a 16-year-old girl who had trauma to the mandibular anterior region about nine years previously. She presented with a lot of swelling and, upon radiographic examination, I discovered she had a very large periapical radiolucency that encompassed teeth #23–26. I found no response to cold in teeth #23–26, percussion tenderness only to #25, and no mobility of the teeth. She was diagnosed with necrotic pulps in teeth #23–26 and acute apical abscess.

My initial treatment was to open tooth #25 for an emergency pulpal debridement, but to also perform root canal therapy on #23, 24 and 26 based on her pulpal diagnosis of all the teeth (and just in case surgical intervention was in her future). I also obtained 3D dental imaging—not to see the lesion, but rather to get an appreciation for the true extent of the bone loss (Figs. 16–18, sagittal, axial and coronal views, respectively). The coronal (Fig. 18) is the view that really puts this case into perspective: This young woman had only a sliver of lingual bone left. Getting her bone back was going to be critical!

5. It Assists in Patient Follow-Ups

The previous tooth story helps demonstrate yet another one of the many cone beam CT benefits, which is assisting in patient follow-ups! The patient’s root canals were completed over multiple visits until the teeth became asymptomatic, at which point the only thing left to do was wait and see what happened.

Fortunately, we were able to recall the patient at six months (Figs. 19–22) and two years (Figs. 23–26) after the procedure, using the CBCT to get a look at her progress. The images show the PA, axial view, sagittal view and coronal view, respectively in each time frame.

Remember: If we can detect disease a lot quicker with the cone beam, the opposite will be true when we are evaluating the same tooth with respect to healing. It will take a lot longer for you to see the bone healing, but it doesn’t mean it’s not happening! And it’s all thanks to endodontic technology like the CBCT that we can follow patients’ progress and see proof of that over time.

6. It Locates Hard-to-Find Canals

To this day, even though I have over 15 years of extensive endodontic experience, some canals can be hard to find—especially the MB2. But even though it’s a challenge to locate, I also know from experience that it’s present in the maxillary first molar about 95 percent of the time. So, when I don’t find one with the microscope, I know I can rely on the diagnostic precision of my cone beam to save the day! 

Here’s a case where the CBCT served multiple purposes, including helping me locate a super hard-to-find canal. My patient was experiencing very vague pain, and we could not reproduce the sensation with traditional testing. Since the periapical radiograph (Fig. 27) showed the teeth to be within normal limits, we took a cone beam scan.

The 3D image (Fig. 28) showed that there was some thickening of the sinus membrane (green arrows) as well as the smallest incipient periapical radiolucency of the DB root (yellow arrows) and a small break in the sinus membrane. This was enough for me to diagnose tooth #14 with a necrotic pulp and to see that the odontogenic infection was having an effect on the sinus membrane. I confirmed my diagnosis of necrotic pulp with asymptomatic apical periodontitis when I started the root canal.

During the procedure, I did everything by the book. But even with my microscope, I could only see three canals (Fig. 29). Of course, I didn’t want to trough too much and take away too much tooth structure if there was no MB2… but since I know there nearly always is, I took another look at the cone beam, with its high-resolution dental imaging, to review the anatomy of the MB root.

In particular, I looked at the axial view (Fig. 30), which can sometimes be the most helpful view for looking at MB2 anatomy. What I saw was that the MB root was very wide in a buccal and lingual direction, with room for two canals. This gave me the information I needed, and I continued to trough apically and look for that MB2 canal.

And suddenly, there it was! A few millimeters below the orifice of the MB, I was able to access the MB2 canal orifice and finish the case (Fig. 31). Without the cone beam’s assistance in finding that fourth canal, this would have been a failed case. But fortunately, there’s nothing my cone beam and I can’t handle! CBCT for endodontists and dentists, is truly a life-changing tool.

The Limitations of Advanced Dental Imaging

Of course, no technology is without its limitations. While CBCT has numerous benefits, it does have some disadvantages that are important to be aware of, with the biggest of them being its susceptibility to human error. After all, a tool is only as good as the hands that wield it! Let’s review each limitation to get a well-rounded understanding of this endodontic technology.

1. It’s Unable to Routinely Detect Cracks

Even with all its advantages, there is one important thing that CBCT can’t do, and that’s routinely detect cracks. This is something that many general dentists don’t quite understand, and I say that because, as an endodontist. I hear so many referring dentists tell their patients that they need a scan in order to see the crack—despite this information being false. Then, when patients arrive at my office, they get frustrated when I can’t deliver that information, and they’re left wondering why their dentist told them that in the first place. 

In reality, I never promise a patient that I’m going to see a crack on the cone beam, because this simply isn’t why I order one! Let me show you an example so you see what I mean.

Crack or No Crack? 

This patient had a previous root canal and a draining buccal sinus tract that was traced to the furcation. Her diagnosis was Previously Treated Tooth and Chronic Apical Abscess. The root canal (done by another professional) looked like it was done really well, but the tooth was never restored with a crown.

We got a CBCT, and here are some snapshots from the scan. This first one (Fig. 32) clearly shows the furcal breakdown and the lateral bone breakdown to the distal root:

The axial view below (Fig. 33) is usually the most helpful view when trying to make this evaluation.

Let me ask you this: Can you visualize the fracture in the image? If so, shout it out right now, and let’s see if you’re right! Keep reading for the answer.

When you’re interpreting advanced dental imaging like a CBCT, be careful about false positives that are actually artifact. When a tooth has a radiopaque material in or near it (i.e., gutta-percha or an implant), watch out for scatter, beam hardening or reconstruction artifact. If you look at the axial slice again (repeated below in Fig. 34 with red arrows), you’ll see several black lines that look like cracks, but are actually nothing at all!

That said, this tooth is cracked—it’s just that looking for a fracture line on the cone beam isn’t how I came to that conclusion. Instead, I looked for patterns of bone loss adjacent to the distal root.

For more info on how to do this, check out this must-read article on vertical root fractures!

Now, how could I be sure this patient’s bone loss was a fracture? Well, because when I send a tooth for an extraction, I request it back so I can correlate the findings back to my cone beam. Here’s what the tooth looked like in my hand:

From these images, you can clearly see the crack along the distal root that starts on the distal marginal ridge and goes all the way down to the apex. This crack is huge, and it never showed up on the cone beam!

Now—I have seen some teeth where their fractures could be detected on the CBCT, but they are the exception to the rule. Generally speaking, if you can see the fracture on the cone beam, you can usually see it on the periapical radiograph, too.

I wish I could say that advanced dental imaging like CBCT could detect cracks and fractures in addition to its many other uses. My job would be so much simpler if that was the case! At the end of the day, though, this tool has its limits, and that’s why I’d encourage you to be careful with what you say to your patients. Let them know what they can and can’t expect from the cone beam.

2. It Doesn’t Show You the Whole Picture

Not only can CBCT not routinely identify cracks, but it also can’t show you the whole picture of what’s going on in the tooth. Sometimes it just doesn’t show you all of the canals, even though they actually exist. There’s a lot going on inside those pearly whites that simply can’t be appreciated unless you take a look inside. Let’s take a look at another tooth story to see why.

When Your Cone Beam Isn’t Enough

The patient in today’s tooth story had originally come to me years ago for a retreatment on tooth #3. Now, she was back with the same problem on tooth #14. She had been having pain on and off that was bad enough to prompt a visit to the dentist, and upon evaluation, her provider found that there was a periapical radiolucency over the MB root. So, she was referred to me for a retreatment yet again. (Coincidence? I think maybe not!)

After proceeding through all of my endodontic diagnostic testing, I found that the patient was tender to percussion on tooth #14, with no response to cold and probings all within normal limits. As a result, I diagnosed the tooth as Previously Treated and Symptomatic Apical Periodontitis #14.

Here was her preoperative radiograph:

And again at a different angle:

And once more as a bitewing:

As per usual, I also made use of 3D dental imaging as part of my endodontic protocol, just to be sure I had the correct diagnosis. In the sagittal view of the cone beam (Fig. 39), I saw the PARL a bit more clearly, which confirmed what I had concluded from evaluation.

But the axial view was where the plot started to thicken. While it doesn’t really look like there’s another canal in the MB root, there was certainly enough space for one. Can you appreciate just how much broader the MB canal is compared to the DB and P canals in Fig. 40?

Even in the coronal view (Fig. 41), it doesn’t seem like there should be an MB2 canal…

Yet I could tell from that lesion that, even though there wasn’t an official fourth canal, there HAD to be a bacterial component in that canal—which means there’s something there that the CBCT wasn’t showing me. Maybe not a whole other canal, but perhaps an area of the MB canal that needed to be extended and cleaned out better.

This is what I mean when I say there are limitations to CBCT in endodontics. Yes, the cone beam is an incredible tool that can provide you a much more detailed view of what’s going on inside of the tooth… but it can’t show you everything! And thinking as much can get you into some serious trouble. 

Fortunately, my many years of experience in practice have shown me the importance of uncovering the full picture, so I decided to open up the tooth to see what was really going on.

Accessing the Tooth for a Clearer Picture

What I saw when I accessed the tooth provided a very different story from what was shown on the CBCT!

There was a groove—which had been invisible on the cone beam—that extended from the MB1, and it was BLACK, meaning it was contaminated. BINGO! In particular, it appeared there was more to the lingual dimension, so I started to instrument that area of the groove. As I worked, I couldn’t believe just how easily my rotary started to glide into that groove.

Here’s a video so you can see exactly what I did:

Did you see at the end of the video? It was like the groove opened up to be a second canal EVEN THOUGH THE CBCT TOLD US IT WASN’T THERE! And did you see all the schmutz that came out? Imagine how much bacteria would have gone undetected had I been unaware of the limitations of CBCT in endodontics.

Here’s the final outcome of the case:

I just love how you can see and appreciate the tiny apical delta of the MB canal!

I hope the main takeaway here is clear: If you want to avoid failed root canals, you need to start thinking and treating in 3D—including beyond the limitations of CBCT in endodontic diagnosis! Had I gone solely off of what was seen on the cone beam, without actually accessing the tooth, I would have done a disservice to the patient. This is the human touch and knowledge through experience that continues to make us clinicians so special!

It’s not just about finding canals, either. It’s about truly understanding the surface area of the canals you see, too. As clinicians, we need to not only look for “dots” on scans, but also the spatial arrangements of the canals with the roots, and really start to try to understand them. Rather than assume the MB2 ISN’T there, assume it IS, and make evaluating just how hard it will be to find part of your risk assessment. Capiche?

3. It’s Expensive to Invest in and Time-Intensive to Learn

A comprehensive guide to CBCT wouldn’t be complete without a transparent discussion of investment, both in terms of money and time. 

As you can imagine, cone beam technology isn’t cheap, and it’s probably the biggest reason I hear dentists cite as to why they’re hesitant to invest in CBCT for their practice. But like any investment, it comes down to the ROI. Given all of the cone beam CT benefits we’ve discussed here, how quickly and easily will you be able to earn back the money you spent? This is the question you should always ask yourself when investing in any technology for your practice.

Integrating CBCT into your workflow is no walk in the park either. It has a steep learning curve, and it’s not something you’re going to be able to start implementing tomorrow! That said, when it comes to bringing any new technology into your practice, it really comes down to simply knowing what to expect. As long as you’re prepared to confront limiting beliefs, deal with some workflow disruption, and improve your knowledge and skills as you go, you’ll be well situated to reap all the benefits that CBCT has to offer!

CBCT vs. Electric Pulp Testing 

One final consideration with regard to CBCT for endodontists and dentists is how it stacks up against electric pulp testing, especially given the conversation we just had about investments.

Not too long ago, I was speaking at an event on endo technology, and I got a question about electric pulp testing. The person asking the question seemed a bit frustrated that I was advocating a $100,000 CBCT machine, while he felt like the EPT, which is more like $100, served him just fine in all his years of practice. While this is a valid question to raise, my opinion after 15+ years in practice as an endodontist is that there is no true comparison. 

While the EPT was useful for me in the past (especially when a cold test wasn’t my friend), I don’t find myself using it much these days. I’m not saying it doesn’t have its place in my practice, but I’ve found that my cone beam has soooo many applications built in that it makes the EPT almost obsolete. I honestly can’t remember the last time I pulled my EPT out.

You know I love using real patient tooth stories to demonstrate my point, so let’s take a look at two cases that exemplify exactly what I mean.

Tooth Story #1: A Confusing Diagnosis

In this first tooth story, I want to start with the referral slip (Fig. 46).

As you may know, I believe that everything starts with a good diagnosis. If your diagnosis is off, the rest of your treatment will be off. In this situation, I could tell right off the bat that this referring dentist was confused. I’m not mocking anyone here! There is SOOOO much to learn in dentistry, and I have the utmost respect for general dentists and how much they have to keep in their heads. You all amaze me, truly! I’m simply offering this example as an opportunity to keep an open mind, learn together, and keep reaching higher and higher.

The referral slip said that tooth #4 was thought to be the culprit tooth, but the tooth was vital and had a draining sinus tract for about 3 months. The sinus tract was traced, and it went to tooth #4. I did my own tracing and found the same thing (Fig. 47).

My diagnostic tests were as follows:

Probings: WNL in the entire quadrant

Percussion: WNL on all teeth in quadrant

Bite: WNL on all teeth in quadrant

Cold: #2: WNL; #3: No Response; #4: WNL and #5: WNL

The only finding was the buccal sinus tract.

Clearly, the diagnosis was confusing for the referring dentist. Even though I could see that the endo on #3 looked a bit suspicious, I always like to be 100% sure and not leave anything to guesswork.

Taking a Closer Look with the CBCT

This I know—a sinus tract will probably trace to a radiolucency in the bone, so I wanted to see the area with high-resolution dental imaging so that I could discover where this RL area might be. Why? Because in this situation, an electric pulp test is not going to help me. We already know that #4 is vital, and there’s no reason to test with an EPT. Plus, #3 had a previous root canal, so the EPT is not going to add any value for this tooth either.  

So, instead, I broke out my CBCT! Here are scans:

You can clearly see the periapical radiolucency on the MB root.

And in the axial view, you can see the etiology of root canal failure is an untreated MB2.

I always love looking at my MB root in the coronal view, because it illustrates so well just how much space there is remaining in the root housing that MB2. Can you appreciate how offset the MB canal is to the buccal? 

Thanks to the cone beam scan’s accuracy, I can now appreciate that there is an untreated MB2, and I also know exactly where it sits in that canal. (We all know it’s never in the same place, right?) I was able to locate it conservatively, and preserve dentin because I can be super selective in where I trough to find the canal.

And here is the final product…

Woohoo! CBCT saves the day!

Tooth Story #2: The Case of a Mistaken Periapical Radiolucency

Let’s take a look at another case, shall we? 

When this patient went to their dentist, they were asymptomatic, had no pain to percussion, and no swelling. An FMX capture was taken, and the dentist saw a periapical radiolucency at the apex of #9.

And here is their preoperative radiograph, blown up bigger so you can get a close look:

And the referral slip…

Now, my PA shows the tooth story a bit differently. I don’t see a PARL in the image. This is another reason why, in endo, we must always take multiple-angled radiographs. There will always be times when things are superimposed over your roots, so this extra imaging can go a long way.

Here is another angle…

But, since this patient was referred to me, I wanted to be 100% certain that I wasn’t missing anything. One of the benefits of cone beam CT is that it gives me that extra layer of confidence and predictability, which is such a crucial advantage to have.

Here were my 3D images:

From these images, I can be 100% certain that the alveolar bone immediately adjacent to the root is pristine. That PDL and lamina dura are stellar, and there is no sign of endodontic pathology around the root. This means my impression of this case was most likely correct. The image that the referring dentist had taken was at an angle in which the nostril was superimposed over the root of the tooth, which is why they thought it was a periapical radiolucency. 

Where Electric Pulp Testing Falls Short

Now, did I need advanced dental imaging like CBCT to tell me this? Probably not. But it also wouldn’t have done any good to use an electric pulp test in this situation, either.

However, as the specialist who acquired this case, I had to be sure I wasn’t missing any disease in the area, and my cone beam is what gave me that confidence. With 3D scans, I could securely diagnose this tooth as Previously Treated and Normal Apical Periodontium #9, and I was also able to determine that no endodontic therapy was necessary at this time.

At the end of the day, the EPT is an all or nothing indicator that doesn’t have anywhere near the range of diagnostic ability as the CBCT. Either the tooth is vital or not—EPT tells me nothing else, especially if a tooth already has a root canal! It will never tell me if any periapical pathology (or any pathology) is present. I often need more information than that in order to triage my patients.  

Sometimes electric pulp test machinery also just straight up isn’t my friend and doesn’t work… which makes it pretty unreliable. For example, it may read out at around 60 or 65 because it’s picking up some sensation from the PDL, making me believe that my tooth is vital when it’s actually necrotic! Not good. 

Now, that’s not to say EPT is entirely useless. I may still use it in calcified teeth or in trauma. But again, as I get more and more experience with my CBCT and the diagnostic precision it offers, I see myself drifting further away from my EPT.

Is CBCT for Endodontists and Dentists Worth It? Absolutely!

Now that we’ve covered everything there is to know about the CBCT, I hope my opinion about this powerful endodontic technology is clear: the benefits of cone beam CT far outweigh any of its disadvantages, and it’s an absolute must to have in your practice!

Whether you’re looking for canals, evaluating resorption or trauma, or simply educating your patients and communicating with your specialists, cone beam technology can significantly improve your practice and will help you save so many more teeth. While it’s not all-powerful—it doesn’t typically show cracks or hidden canals (if you don’t know what to look for), for instance—it’s an important tool for any dental professional, and it’s well worth the investment of both time and money.

Are you ready to integrate CBCT into your practice? Apply for E-School with Coaching, my online endodontic CE course for dentists of ALL kinds who are looking to boost their endo confidence. It’s a course built around 10 weekly group coaching calls (with yours truly!) designed to take your endo to a level you never thought possible—whether you already do endo or not.

– Sonia

For advanced training, explore our MB2 canal identification resources.