3 Questions Every Dentist Should Be Able to Answer After Opening a CBCT — And Most Can't

Let's do something most CBCT articles don't do. Instead of explaining what CBCT is, or listing its clinical applications, or telling you how useful 3D imaging has become — let's just ask you three questions. 

No tricks. No specialist-level diagnostic puzzles. Just the baseline — the floor-level competency that every CBCT reading should start with. Three questions that a dentist with proper CBCT training answers without thinking. Automatically. Every single time. 

Go through them honestly. Note where you hesitate. 

The scan is open. The images are on the screen. The clock is running. Here we go.

1

Which plane are you currently looking at — and which direction is which?

Not the name of the plane. The orientation. Right now. In the viewer you actually use.

CBCT gives you three simultaneous views: axial, coronal, sagittal. You know those terms. That is not the question. 

The question is: when you open your viewer — your actual software, on your actual computer — which window is which? And within each window, which edge is anterior? Which is the patient's right? Which direction does the scroll move — superior or inferior, anterior or posterior? 

Because here is the thing. Every CBCT software renders orientation slightly differently. Some mirror the axial. Some display the coronal from behind the patient, not in front. Some label it clearly. Some don't. And if your patient's scan was taken at a different centre on a different machine, the default orientation may not match what you trained on. 

A dentist who scrolls in the wrong direction — thinking they are moving anteriorly when they are actually moving posteriorly — places every subsequent landmark in the wrong position. The reading feels confident. The anatomy is in the wrong location.

So: right now, without opening a viewer to check, can you describe the orientation convention in the software you use most? Can you do it for a software you haven't used before? 

If there is any hesitation in your answer — keep going.

2

Is your window and level set correctly for what you are trying to see?

The same scan. Different settings. Completely different picture.

CBCT images display tissue density on a grayscale. Dense structures — enamel, cortical bone — appear white. Air and soft tissue appear dark. Between those extremes sits everything you are actually trying to evaluate: trabecular bone, a periapical lesion, the soft tissue floor of the sinus, the cortex of the IAN canal. 

How much of that range you can see at any given moment is controlled by window width and window level. Window width determines the range of densities displayed. Window level sets where the midpoint of that range sits. Together, they determine what you can and cannot see on the screen in front of you. 

The default windowing that loads when you open a scan is a general-purpose setting. It is designed to show everything at once. It is not designed to optimise contrast for the specific tissue you are assessing. It is a starting point, not a reading position. 

A periapical lesion in its early stages can be invisible on default windowing — and clearly visible when the window is narrowed and the level shifted to the relevant bone density range. Dentists reading on default settings miss these. Not because they are not looking. Because the display is not showing them. 

So: do you know how to adjust windowing in your CBCT software? Do you know what settings to use for bone assessment versus a soft tissue query? When you look at a scan, do you verify the windowing before you start reading — or do you read whatever the software showed you first? 

If the answer is 'I usually just use what loads' — that is an honest answer. It is also information.

3

Have you identified the key anatomical landmarks before reading anything clinical?

Not 'can you find them eventually.' Before you start interpreting — immediately.

Every CBCT case has a set of anatomical landmarks that need to be located and confirmed before clinical interpretation begins. In the posterior mandible: the inferior alveolar canal — its exact course, its depth from the crest, whether it runs buccal or lingual to the planned site. In the posterior maxilla: the sinus floor, the sub-antral bone height, whether septa are present. In any extraction case: the mental foramen and its exact position relative to the root apices. 

The question is not whether you can find these structures if you look long enough. The question is whether you locate them deliberately, systematically, before you start drawing clinical conclusions — or whether you go looking for them only after something in the image prompts you. 

Because the mental foramen has anatomical variants that position it more superiorly than expected. It can look — on a quick review, at default windowing, in the wrong plane — like a periapical lesion. The IAN canal in a patient with dense mandibular bone can be difficult to trace if you do not know which plane to view it in and how to adjust the window to improve cortex visibility. 

Identifying a landmark incorrectly, or not identifying it at all before reading, is not always obvious in the moment. The error becomes visible later — when the surgical finding does not match the pre-operative assessment, when the patient reports symptoms that the scan 'didn't show', when a second opinion reveals something that was present from the start.

So: the next time you open a CBCT, try this. Before you look at anything else, locate the three or four landmarks most relevant to the clinical question. Deliberately. One by one. Confirm them. Then start reading. 

Notice how long it takes. Notice whether it feels systematic or whether you are hunting.

Here's What Those Three Questions Are Really About 

None of them are diagnostic questions. None of them require specialist knowledge. They are orientation, display, and landmark confirmation — the three things that happen before any clinical reading begins. 

And the reason they expose a gap for most dentists who have not had structured CBCT training is not because the dentists are not capable. It is because these foundational steps are almost never taught explicitly. They are assumed. The machine is given, the software is demonstrated, and the clinician is expected to pick up the rest. 

Some do. The gap stays hidden until it matters. 

Confidence in CBCT reading is not the same as competence. The dentist who is uncertain knows they need to look harder. The dentist who is confident but untrained looks in the wrong place and does not know it. 

That distinction is worth sitting with.

One Last Thing 

Go back to the three questions. Not the explanations — just the questions themselves. 

Which plane am I on, and which direction is which? 

Is my windowing set correctly for what I am trying to see? 

Have I confirmed the relevant anatomical landmarks before I start reading? 

If you can answer all three confidently and automatically every time you open a scan — you have the foundation. Everything else builds from there. 

If any one of them gave you pause, you now know exactly where the gap is. That is not a bad place to be. A known gap can be closed. An unknown one cannot.

Still unsure about any of the three?

CBCT Basics at DMD Imaging is where that changes.

Frequently Asked Questions

• I've been using CBCT for two years. Should I already know all of this?

  Two years of exposure and two years of training are different things. Exposure builds familiarity with what scans typically look like. Training builds the systematic protocol that catches what a scan looks atypical in. Many dentists with significant CBCT experience have strong instincts on familiar cases and genuine uncertainty on cases that deviate from the norm. The questions above are designed to reveal exactly that boundary.

• Is this only relevant for dentists doing implants and surgery?

  No. CBCT is now ordered for endodontic assessment, orthodontic planning, TMJ evaluation, and general diagnostic queries. The orientation, windowing, and landmark questions apply equally regardless of why the scan was taken. A dentist who cannot orient a CBCT correctly is at risk of misreading any case — not just surgical ones.

• Can I just learn this from watching YouTube tutorials?

  You can learn what the words mean. You can learn roughly what each plane looks like. What you cannot get from a tutorial is the supervised, case-based practice of applying the protocol on real datasets across varying anatomy, software, and clinical presentations — and receiving feedback when you get it wrong. The difference between understanding a concept and executing it reliably under clinical pressure is practice with correction, not passive viewing.