Chapters
What Is Co-Discovery?
[00:00:53 – 00:02:40]
Co-discovery is an approach to dental care that treats patients as informed partners rather than passive recipients of information. Originating with American dentist Dr Bob Barclay in the 1950s, it involves sitting with patients to explore what their x-rays and clinical findings actually show — before any diagnosis is made.
The goal is understanding, not just instruction. When patients can orient themselves on an x-ray — identifying tooth crowns, roots, and surrounding bone — abnormal findings become far easier to grasp. Seeing is believing, and co-discovery replaces fear with clarity.
Light and Dark: The Basics of X-Ray Contrast
[00:02:40 – 00:04:33]
White areas on a dental x-ray represent dense structures that block radiation — enamel, dentine, bone, and metal restorations. Metal fillings and crowns appear very bright, while tooth-coloured fillings sit somewhere in between.
Dark areas indicate where x-rays pass through more easily. Cavities appear dark because mineral has been lost from the tooth, making it less dense. Bone loss shows up as a lowering of the bone level around the root, visible when one tooth’s bone sits noticeably lower than its neighbours.
How Cavities Appear on X-Rays
[00:04:34 – 00:06:01]
A healthy tooth has a smooth, uniform outline with no dark shadows penetrating the enamel or dentine. A cavity typically appears as a dark triangle or irregular shadow, most often between teeth just below the contact point — where plaque accumulates — or beneath an existing filling.
Early decay can be subtle, while advanced decay is far more obvious. Importantly, not all cavities are visible on x-rays alone; very early surface decay may only be detected during a clinical examination. X-rays are most reliable when used alongside a hands-on assessment, not in isolation.
Spotting Bone Loss and Gum Disease
[00:06:02 – 00:06:50]
In a healthy mouth, bone sits one to two millimetres below the point where the root meets the crown. Bone loss appears as a lowering of this level, making the root look longer than usual. In advanced cases, the loss may be uneven or angular rather than uniform.
Patients who can visually identify bone loss on their own x-rays are consistently more likely to follow through with gum treatment and ongoing maintenance. Seeing the evidence transforms gum disease from an abstract concept into something tangible and motivating.
Abscesses, Infections, and Root Tips
[00:06:51 – 00:07:42]
An abscess typically appears as a dark, circular or irregular shadow around the tip of a root, indicating bone destruction caused by chronic infection. Early infections can be missed on standard 2D x-rays but may become visible on a CBCT (cone beam CT) scan, which provides a three-dimensional view.
Accurate diagnosis relies on correlating imaging findings with the patient’s symptoms — a single snapshot is rarely sufficient on its own.
Bright White Areas: Restorations and Artificial Structures
[00:07:42 – 00:09:17]
Bright white shapes on an x-ray usually indicate artificial structures such as implants, crowns, posts, or fillings. A full crown can block the view of the tooth beneath it, which is why decay hiding under a restoration can sometimes go undetected — making regular monitoring essential.
How frequently x-rays are taken depends on a patient’s history: those with many fillings and crowns may need them every 18 to 24 months, while lower-risk patients may go up to three years between sets. CBCT scans offer excellent detail for root and bone assessment, though extensive metalwork in the mouth can cause image distortion.
Tartar Below the Gum Line
[00:09:18 – 00:10:40]
Tartar, or calculus, appears on x-rays as white, irregular, chalky deposits on the teeth. Above-the-gum tartar is primarily a cosmetic concern and is removed during a professional clean. Subgingival tartar — calculus that has formed below the gum line — is a more serious finding and is almost always associated with bone loss.
Patients are often surprised to see tartar on an x-ray, particularly if their gums look healthy in the mirror. Smokers, in particular, can have pink, seemingly healthy gums while harbouring significant tartar and bone destruction beneath the surface. Seeing this on an x-ray is often a powerful motivator for seeking treatment.
Floating Teeth and Advanced Gum Disease
[00:10:41 – 00:11:56]
A tooth that appears to be floating on an x-ray has lost nearly all of its surrounding bone support. This level of bone destruction is typically associated with very advanced, long-standing gum disease and is more common in smokers and people with poorly controlled diabetes.
Most floating teeth cannot be saved. When several teeth show this pattern, it is often an indication that neighbouring teeth are not far behind.
How AI Helps Patients Understand Their X-Rays
[00:11:57 – 00:14:04]
AI software such as Diagnocat analyses dental x-rays and CBCT scans, using colour overlays to highlight areas of concern — cavities, abscesses, tartar, and signs of wear. This makes it easier to walk through findings with a patient and discuss them openly, improving both diagnostic consistency and patient understanding.
AI is a tool to support clinical judgement, not replace it. Dentists may spot things the software misses, and vice versa. However, patients should be aware that AI-assisted analysis can be misused to over-diagnose treatment. Knowing what questions to ask — and understanding that early enamel shadows do not automatically require fillings — is an important safeguard.
Why Seeing Is Better Than Being Told
[00:14:05 – 00:16:05]
A thorough examination at OptiSmile includes photographs, a 3D digital scan, 2D x-rays, and where relevant a CBCT, all reviewed together with the patient before any treatment discussion begins. This process of co-discovery allows patients to see cracks, wear, bone levels, and decay for themselves — in their own mouth, not just described in abstract terms.
When patients and dentist explore findings together, it becomes possible to distinguish what genuinely needs attention from what can be monitored, and to address concerns on both sides. Something that troubles the patient but not the dentist can be discussed openly; something the dentist notices but that does not yet affect the patient can be kept under review rather than treated prematurely.
Being told creates dependency; seeing creates understanding. Co-discovery empowers patients to protect their teeth, their health, and their finances more effectively over the long term.
Transcript
Eon Engelbrecht (0:04)
Welcome back to Save Your Money, Save Your Teeth. Now, when the dentist puts your x-ray up on the screen, most of us just nod along and hope for the best. But what if you could actually read the story your own mouth is telling? Today, Dr Clifford Yudelman introduces co-discovery, the idea that you’re a partner in your own care and not just a passive bystander. He’ll show you how to make sense of the light and the dark, spot the warning signs, and turn fear into clarity. Dr Yudelman, welcome back once again.
Dr Clifford Yudelman (0:39)
Thank you, and thanks for having me back. I hope you had a great week and that you did your dental emergency kit. It’s all ready to go.
Eon Engelbrecht (0:53)
Oh yes, I’m looking forward to that once summer is back. Co-discovery — you talk about co-discovery. What should I be looking for on my x-ray?
Dr Clifford Yudelman (1:04)
Co-discovery isn’t something that I invented. It was brought about by a dentist, Dr Bob Barclay, in the 1950s. He was a famous dentist in America, and he taught other dentists how to sit down with patients and explain to them what’s on the x-rays. He took photos back in the day, they used to use colour slides, or a mirror and big diagrams, really explaining to a patient what’s going on in their mouth before actually diagnosing anything, just to discover what was actually going on.
Co-discovery means the patient isn’t a passive recipient of information but an informed partner in the decision-making. When you look at your own dental x-ray, you’re not expected to diagnose yourself but to understand the story your mouth is telling. Start by orientating yourself: identify the crowns of the teeth, the roots, the surrounding bone. A healthy x-ray shows well-defined tooth structures and bone levels that hug the roots closely.
Once patients understand what normal looks like, abnormal findings make far more sense. Patient-centred care, where visual engagement occurs, improves understanding, trust and long-term compliance, because as we say, seeing is believing, and co-discovery replaces fear with clarity.
Eon Engelbrecht (2:40)
But I want to ask you, what is the difference between the white areas and the dark areas on an x-ray?
Dr Clifford Yudelman (2:49)
On dental x-rays, white areas represent very dense structures that block radiation. There’s enamel, which is whiter than dentine, then there’s bone, which looks fuzzy, and then you’ve got metal restorations. Metal restorations like a gold inlay or a silver filling look very, very white — they don’t let the x-ray through at all — and a white filling may be somewhere in between.
The dark areas represent places where the x-rays pass through more easily, such as in between your teeth, basically air. The gums are very faint, almost black, but you can see them if you change the brightness. Hopefully everyone’s using digital x-rays now, so you can change how bright or dark they are.
Areas where there’s infection in the bone, and where there are cavities in the teeth, look darker because they’re less dense. Understanding this contrast is the foundation of looking at x-rays. With a cavity, the mineral — the actual calcium — has been lost out of the tooth, so the x-ray goes through that part of the tooth more easily. Bone loss shows up as a lowering — you can see the bone around the neck of the tooth, or around where your enamel ends, and then you might get a tooth where the bone is much lower down, not in line with the others. This basic principle lets you follow along with any explanation the dentist gives you, rather than just relying on some vague description.
Eon Engelbrecht (4:34)
I was going to ask you now, how does a cavity look on an x-ray compared to a healthy tooth? So it’s a light and a dark difference.
Dr Clifford Yudelman (4:42)
Yes, but there’s a bit more detail to that. Once you know how to look for cavities, it’s actually not that difficult with digital x-rays. A healthy tooth has a smooth, curvy, uniform outline with no dark shadows penetrating the enamel or the dentine. A cavity appears usually as a dark triangle or irregular shadow, often just between the teeth, right where the teeth touch, but just below — because that’s where the plaque builds up — or underneath an existing filling, which is called recurrent caries.
Early cavities can be quite subtle, while advanced decay is a lot more obvious. Importantly, not all cavities are visible on x-rays, and very early surface decay may only be seen clinically — which means when the dentist looks in your mouth. But x-rays are a powerful diagnostic tool when used alongside a clinical exam, not just in isolation. It’s very difficult for dentists to look at x-rays and say, oh, you need five fillings. You might have five shadows, but not all of them may need fillings, because you generally can’t just look at x-rays on their own.
Eon Engelbrecht (6:02)
And would you be able to spot bone loss on your x-rays by yourself?
Dr Clifford Yudelman (6:09)
Yes, you can, because in a healthy mouth the bone typically sits one or two millimetres below the junction where the root and the crown meet. Bone loss shows up as a lowering of this level, creating a longer visible root. In advanced cases the loss is uneven or angular. Patients who visually understand bone loss are consistently more likely to follow through with gum treatment and maintenance, and seeing bone loss changes this whole abstract idea of gum disease into something that’s actually visible.
Eon Engelbrecht (6:51)
And how do you spot an abscess or infection at the root tip, doctor?
Dr Clifford Yudelman (6:56)
An abscess often appears as a dark circular or irregular area around the tip of the root, and that indicates bone destruction caused by a chronic infection. Not all infections are visible immediately — the early ones can be missed on x-rays. Often we take a 2D panoramic x-ray and it doesn’t show anything, then we do a CBCT and we can see that one or more of the roots on a molar has a big shadow around it that isn’t easily visible on a normal 2D x-ray. Evidence-based dentistry relies on correlating the imaging and the symptoms, not just a single snapshot.
Eon Engelbrecht (7:42)
And then I also want to ask you, what do bright white streaks or shapes usually mean on x-rays?
Dr Clifford Yudelman (7:49)
We mentioned before that a lot of the time it’s something that’s more dense — it doesn’t allow the x-rays to pass through. So it could be implants, crowns, posts, fillings, things like that. White fillings may be slightly less opaque. Understanding what’s artificial versus natural helps put things in context. If you’ve got a full crown, it actually blocks the view underneath it, which is why recurrent decay can sometimes be hidden.
That’s why regular monitoring matters: if somebody’s got lots of fillings and crowns, we may do x-rays every 18 to 24 months, but if someone hasn’t had many or any fillings, we may go as long as three years. CBCT is very good for seeing abscesses and problems with roots and root structure, and bone loss. But CBCTs are very sensitive to lots of metal in the mouth, and a patient who’s had a lot of crowns or implants can produce a CBCT full of streaks. And that’s where AI can actually help.
Eon Engelbrecht (9:18)
Yes, definitely. But I also want to ask you, how can I tell if there’s tartar or calculus on the x-ray?
Dr Clifford Yudelman (9:25)
Great question. Tartar or calculus is that white, irregular, chalky stuff that builds up on your teeth. If it’s above the gum, it’s mainly cosmetic — it should just get cleaned off. I had a wonderful cleaning on Friday with my hygienist; we have a new machine that uses an air polish, a very, very fine machine that actually removes the tartar, you don’t even feel it, it’s amazing — it’s a Swiss machine.
But where it really comes in handy is when you’ve got tartar below the gum line, and you can see that on x-ray very well — it’s called subgingival, or under-the-gum, tartar. And that almost always has bone loss with it, which is basically gum disease. Patients are often surprised to see tartar or calculus on the x-ray, because it isn’t always visible in the mirror, especially in smokers, who can have pink, healthy-looking gums and a lot of tartar under the gum. When people see this tartar under the gum and their bone being destroyed, that really motivates them to get something done about it. And the AI is really good for showing tartar under the gum.
Eon Engelbrecht (10:41)
And if you look at an x-ray, why do some teeth look like they are floating? Does it mean they are loose?
Dr Clifford Yudelman (10:47)
Yeah, basically. If you see a tooth that’s floating — and I’ve seen a few in the last year or so — there’s no bone around it. Sometimes that’s in someone with very advanced gum disease who hasn’t had care for a good few years, often smokers, people with diabetes, where the gum has receded all the way around the tooth and there’s hardly any bone left. It’s usually people with very advanced gum disease, and most of those floating teeth can’t be saved.
At OptiSmile, it’s very rare that we see a lot of that, but there could be the odd tooth. We sometimes do pro bono or charity work and help someone out by removing a couple of teeth that are loose like that, but it’s not that common. It’s quite sad. Sometimes if you’ve got two or three floating teeth, it means the rest of them are not far away from floating either.
Eon Engelbrecht (11:57)
Gosh, that’s quite hectic. Now you can talk about AI, doctor, I know you love your AI. So I want to ask you, how does AI technology help patients understand their x-rays better?
Dr Clifford Yudelman (12:10)
Yeah, we love our AI. We use software called Diagnocat — I’ve been using it for about six years. They’re great, they’re putting on a lot of online lectures lately, a lot of dentists in South Africa are getting into AI. Overseas there are quite a few different AIs available, but Diagnocat is the best one, especially for looking at a CBCT, because there’s so much information on there. It actually colour-codes — it shows you where the abscesses are, where the cavities are, where the tartar is. It even finds things you’re not normally supposed to see on the x-ray, like attrition or abfraction.
The colour overlays are fantastic. It doesn’t replace a dentist’s judgment, it just helps with the conversation. Sometimes I see things the AI hasn’t seen, but it also happens the other way around — the AI sees something and I think, wow, I almost would have missed that. You can look at the things the software is flagging and discuss them openly with the patient. It has been shown to improve diagnostic consistency and also help patients understand, but it’s got to be used responsibly.
In the wrong hands, a dentist can turn up the heat on it and show patients five or ten so-called cavities that are only just starting in the enamel and barely visible. Those don’t need to be filled at that point, but someone could turn it around and tell the patient the AI says they need fifteen fillings. People need to be very aware that AI-assisted x-rays are not being used to oversell or over-diagnose treatment, and that’s where knowing what questions to ask is very important.
Eon Engelbrecht (14:05)
And just finally, why would you say it’s important for patients to see the x-ray, not just to be told what’s wrong?
Dr Clifford Yudelman (14:13)
I always take photos of patients, I do a 3D scan of their teeth, then we take a 2D x-ray and I look at it. If there are any abscesses, root canals or wisdom teeth, I’ll include a 3D x-ray. We put all of those x-rays through the AI, and then I sit down with the patient. We look at the x-rays, the photos, the scan. This is all part of a one-and-a-half-hour exam. I tell the patients, don’t worry, the last ten or fifteen minutes we’re going to actually look in your mouth, and we sit and look at all of it together.
That way you can see the cracks with the photos, you can see on your scans where your teeth are worn down, you can see everything. This is just discovering — co-discovery — before diagnosing actual treatment, or discussing how we can fix it, or whether it even needs fixing, or something bothers me but it doesn’t bother the patient, or vice versa. Something bothers the patient and I reassure them, no, it doesn’t bother me, but we can meet halfway. Say it’s a little black stain on the top of a back tooth that doesn’t actually need a filling — it might really bug the patient, but generally those little black stains we leave alone.
It also helps patients accept the need for treatment, so in turn they get treatment done, which means it doesn’t get worse — they can get things done while it’s still treatable and small, and it reduces anxiety. You get an improved long-term outcome when patients are involved. Being told creates a dependency, but seeing creates understanding, and co-discovery empowers the patient to protect their teeth, their health and their finances more effectively over their lifetime.
Eon Engelbrecht (16:05)
And that’s co-discovery in a nutshell. Dr Yudelman, thank you so much, this was very, very interesting, and we’ll certainly look at x-rays with different eyes next time.
Dr Clifford Yudelman (16:16)
Yeah, and mentioning nutshells, just be careful if you’re eating granola that you don’t break a tooth on a nutshell.
Eon Engelbrecht (16:22)
Yeah, that’s very likely. That and popcorn, just those kernels, they are just terrible for your teeth — if you bite the wrong way it’s goodbye.
Dr Clifford Yudelman (16:35)
Some of my best friends have lost their nutshell. They’re just plain nuts.
Eon Engelbrecht (16:40)
I love it. Dr Yudelman, thank you so much, and also to our listeners, thanks for joining us. For more, visit OptiSmile.co.za. We’ll see you next time, and until then, look after your teeth and they will look after you.
Announcer (17:15)
Discover the world of dental excellence with OptiSmile. Join us for a weekly podcast featuring Dr Clifford Yudelman, a seasoned expert with 40 years of dental experience across four continents. Gain unique insights and expert dental advice by visiting OptiSmile.co.za for articles that illuminate the path to optimal oral health. If you’re seeking unparalleled dental care in Cape Town, get in touch with OptiSmile or book directly online at OptiSmile.co.za. OptiSmile, where global expertise meets local care.
Disclaimer: The content provided in this podcast, “Save Your Money Save Your Teeth” on Medical Mondays, is for informational and educational purposes only. It is not intended to serve as dental or medical advice. The insights and opinions expressed by Dr. Clifford Yudelman and any guests are designed to foster a better understanding of dental health, preventive measures, and general well-being, but should not be interpreted as professional dental or medical recommendations.Dr. Clifford Yudelman does not diagnose, treat, or offer prevention strategies for any health conditions directly through this podcast. This platform is not a substitute for the personalized care and advice provided by a licensed dental or healthcare professional. We strongly encourage our listeners to consult with their own dental care providers to address individual dental health needs and concerns.The information shared here aims to empower listeners with knowledge about dental health but must not be used as a basis for making health-related decisions without professional guidance. Your dental care provider is the best source of advice about your dental and overall health. Please always seek the advice of your dentist or other qualified health professionals regarding any questions or concerns about your dental health.
