Chapters
Why a single tooth turns grey or black
[00:00:04 – 00:03:21]
A mouth of healthy white teeth with one grey, brown or near-black front tooth is a common sight, and most people buy the wrong fix. The tooth has usually died quietly, often after a childhood knock that never hurt and was never looked into.
A blow can kill the nerve without breaking the tooth. Blood products then break down inside the dentine and stain it from within, and because enamel is translucent, that stain shows straight through.
Not every dark tooth is dead — some keep a little nerve and can still be lightened with ordinary teeth whitening. That is why the tooth should always be x-rayed and vitality tested first, with a referral to a specialist if there is any doubt.
Does a root canal darken the tooth?
[00:03:21 – 00:04:38]
A common myth is that a root canal ruins a tooth by turning it dark. A well-done modern root canal treatment does not darken a tooth — the staining is usually already under way before treatment begins.
Older materials were more likely to discolour teeth. A silver filling placed behind a front tooth can corrode over time, and that dark colour works its way through to the front — but that is the filling, not the root canal.
Properly sealed modern root canals rarely cause darkening. The myth matters because it can push people to refuse a treatment they genuinely need.
Why whitening trays can’t fix a dead tooth
[00:04:39 – 00:05:42]
Once a tooth has died and darkened from the inside, external whitening does little. Bleaching the outside simply cannot reach a stain that sits within the dentine.
In fact, it can make things look worse. Whitening every other tooth while the dead one stays dark only increases the contrast.
Some patients arrive having been told a root-treated tooth will always be dark. That is not the end of the story — there is a better option coming up.
Internal bleaching, or the “walking bleach” technique
[00:05:43 – 00:10:32]
Internal bleaching, or the “walking bleach”, has been around for almost a century and treats a dark tooth from the inside. Working through the small access hole at the back of a root-treated tooth, the dentist first checks on x-ray and under magnification that the root filling is sound and not leaking.
A little of the root filling is removed to just below the gumline and sealed over with a glass ionomer cement, protecting the root. A 35% hydrogen peroxide gel is then placed inside, the tooth is closed, and the bleach is left to work for several days — hence “walking bleach”.
The patient returns, the bleach is removed and a permanent filling placed. Results usually appear quickly and can last for years or even permanently, with a simple repeat if needed. In South Africa the whole process typically runs from around R3,000 for the first visit to roughly R9,000 for all visits combined.
Does it hurt?
[00:10:34 – 00:11:08]
Because the nerve is already gone, there is nothing to feel and no anaesthetic is needed. Most people are surprised by how straightforward it is.
The only odd part is knowing something is sealed inside the tooth for a few days. It is far gentler than having a tooth drilled down for a crown.
Is it safe, or can it damage the root?
[00:11:09 – 00:13:01]
Done properly, internal bleaching is safe and predictable. The old risk was external resorption — damage to the outside of the root — if bleach leaked past a poorly sealed filling.
Once dentists learned to seal the tooth correctly, that risk largely disappeared. The key is an experienced operator working with loupes or a microscope who follows the protocol.
If a dentist has little experience with the technique, it is worth asking how many they have done, or seeing a specialist. In the right hands it is a simple procedure.
How long does it last — will the tooth go dark again?
[00:13:01 – 00:14:03]
Internal bleaching can last for years, and in some cases indefinitely. Teeth do age, though, so the colour can drift slightly over time.
Sometimes the neighbouring teeth darken instead, leaving the bleached tooth looking too light. Either way, a quick touch-up with whitening trays or a repeat internal bleach sorts it out.
That is a far cheaper and gentler cycle than replacing a crown every decade or so.
How many visits, and when the colour matches
[00:14:04 – 00:15:13]
The treatment is a few short, easy appointments. The most important step is confirming on x-ray — or a 3D CBCT scan — that the root filling is completely sound before starting.
The colour is checked under daylight with a shade guide and photographs along the way. The final restoration goes in once the match is right, and the result can look good in as little as three or four days.
Why not just fit a veneer?
[00:15:13 – 00:17:08]
A veneer always means drilling away healthy enamel, and once enamel is gone it cannot be bought back. To hide a dark tooth, a veneer also has to be made unusually opaque and white.
That creates the opposite problem — one glaringly white tooth. The common “solution” is then to veneer the neighbours too, so some patients are talked into six or ten dental veneers just to make everything match.
A single dark tooth rarely needs any of that. The guiding rule is simple: choose what is reversible, or at least does no damage to the tooth.
What internal bleaching saves you versus a crown
[00:17:08 – 00:20:23]
Beyond cost, internal bleaching saves the tooth itself. A common over-treatment is a post cemented into the tooth followed by a crown, after filing away most of the enamel.
A post and crown on a slender lateral incisor carries a real risk of snapping at the gumline years later — effectively a future implant. Any dental crown also needs replacing every ten to fifteen years, and matching a single crown to its neighbours is expensive and difficult.
The cheapest dentistry over a lifetime is almost always the least invasive. After bleaching, a tooth left as a strong enamel shell can be rebuilt with a Kevlar-fibre-reinforced filling, restoring much of its original strength without a crown or veneer.
The takeaway
[00:20:23 – 00:20:48]
A dark tooth is a colour problem, not always a damage problem. Before anyone reaches for a drill, the first question should be whether it can be treated from the inside.
Enamel is the one thing in your mouth you cannot buy back. Protecting it is almost always the smarter choice for both your health and your wallet.
Transcript
Eon Engelbrecht – E-Radio-SA (0:04 – 0:45)
Welcome back to Save Your Money, Save Your Teeth, and today we are talking about one tooth, just one. You’ve seen
it: a mouth full of healthy white teeth, and then one front tooth sitting there looking a bit grey or brown, or sometimes
almost completely black. But most people who have that tooth end up buying the wrong solution. Some spend on
whitening — it was never going to work. Others get talked straight into a veneer or crown. And there’s a third option. It is
nearly a century old, and hardly any patient has heard of it. Dr Clifford Yudelman of OptiSmile is back with us again
here today. Welcome back, doctor.
Dr Clifford Yudelman – OptiSmile (0:45 – 0:54)
Hi Eon, thanks for having me back. Great to be back. And yeah, today is a very important episode because we do see a
lot of these types of issues.
Eon Engelbrecht – E-Radio-SA (0:55 – 1:11)
I’m looking forward to learning more today along with our listeners. And I want to ask you firstly, why does a single
tooth sometimes turn grey or even black years after a knock, when nothing else about it seems wrong?
Dr Clifford Yudelman – OptiSmile (1:12 – 3:21)
So the tooth died quietly, and nobody told the patient — and the patient didn’t know about it either. The knock actually
kills the nerve without breaking anything, because it never hurts and it didn’t get investigated. And the blood products
break down inside the dentine, or the centre of the tooth, and it stains from within. And enamel is actually translucent —
it’s kind of see-through. It’s a window, and the stain shows through. So you get hit by a hockey ball or a squash racket
when you’re fifteen. And then at around twenty or thirty years old, you get a photograph taken and your tooth is just
looking darker and darker when you’re in photos. And basically, the tooth is structurally sound, but the colour is not the
damage — it’s a sign that there’s actually historical damage inside the tooth. Sometimes the tooth can go dark and still
have some nerve in it, and the tooth can be a little bit more opaque, but the tooth is still vital — there’s still some nerve
left behind. And those teeth can be whitened externally, just with teeth whitening trays. We’ve done six podcasts on
whitening, but you basically whiten all your teeth and then you continue to whiten that one tooth. You wouldn’t
especially go and get a root canal. While we’re on that, actually, you have to make sure that the dentist x-rays the tooth. If
they don’t know too much about it, they should send you to an endodontist. You need to do vitality testing on a tooth like
that — an ice test, checking that there’s no widening at the periapical ligament, which means that at the end of the root
there isn’t a little shadow — because sometimes those teeth, other than the colour, don’t need a root canal. So I wanted to
just throw that in since we’re talking about a single dark tooth.
Eon Engelbrecht – E-Radio-SA (3:21 – 3:33)
And that brings me to my next question. Now that you mentioned root canals, is it true that a root canal actually darkens
the tooth, or is it the materials that get used?
Dr Clifford Yudelman – OptiSmile (3:33 – 4:38)
So a well-done modern root canal doesn’t darken the tooth. The staining is generally already underway when the root
canal gets started. Some of the older materials could have darkened teeth. We see patients who’ve had a root canal and
then the dentist put a silver filling in the back of the front tooth, and eventually you get corrosion and a dark colour from
the amalgam — it works its way through the tooth to the front, or there’s leaking in the filling and the inside of the tooth
goes brown. That’s not necessarily from the root canal. These days, if someone has an injury to a tooth and gets a root
canal that’s properly sealed, those teeth don’t generally go dark. The thing is, that’s a myth — the patient says the root
canal ruined the tooth, and then years later they don’t want another root canal because they say the tooth goes dark
anyway. So it’s not always the case.
Eon Engelbrecht – E-Radio-SA (4:39 – 4:45)
Can ordinary whitening trays fix a tooth that has died and gone dark?
Dr Clifford Yudelman – OptiSmile (4:45 – 5:42)
In the case where you’ve already had a root canal and the tooth is very dark, external whitening with trays or in-chair
doesn’t really help very much. In fact, it can make the situation look worse, because you’re bleaching all the other teeth
and that tooth stays dark, so the contrast is much more and it looks even worse. We’ve had patients come from other
dentists where they’ve had in-chair whitening and trays, and the dentist says, no, you’ve got a root canal in that tooth,
your tooth will always be dark. And they start telling you about other things that I think will come up later with some
further questions. Just need to be aware of that. We’ll give you some solutions shortly — stay tuned.
Eon Engelbrecht – E-Radio-SA (5:43 – 5:50)
What exactly is internal bleaching, or what dentists call the walking bleach technique?
Dr Clifford Yudelman – OptiSmile (5:50 – 10:32)
So it’s apparently been around for almost a century. Normally there’s a little access, or a hole, at the back of the tooth
where the root canal was done, on the palatal side. That gets cleaned out — sometimes that’s the actual culprit, so the root
canal needs to be checked on the x-ray. Let’s just say, in the case where the root canal is fine, when the dentist removes
the old filling at the back of the tooth, they also need to look at the root canal filling with a microscope and see that there
isn’t already what’s called leaking of the coronal seal. So corona, or crown — not the beer. There’s a seal at the apex, at
the root tip, and then there’s a seal at the top of the tooth, and if there’s any stain or it’s kind of gunky there, that means
the root canal should be retreated before any walking bleach or internal bleaching. So yeah, I will get a bit technical,
because someone who’s up against this obviously wants to know. So what we then do is we actually take the edge of that
root canal filling down to just below what’s called the CEJ, which is where the enamel, the root, and the top of the tooth
join. The dentist has to drill away some of the root canal inside the tooth. It’s not painful — you don’t need anaesthetic, in
case somebody’s already getting nervous. You remove some of the root canal filling — it’s called GP, or gutta-percha,
depending what country you’re in. And then you have to seal over the top of the root canal, usually with something called
glass ionomer — it’s a type of cement or sealing filling. And then we use hydrogen peroxide. There’s actually one that’s
off the shelf called Opalescence Endo — endo meaning inside. Endodontist means a dentist that treats the inside of the
tooth, so Opalescence Endo is made for walking bleach, or internal bleaching. It’s a 35% hydrogen peroxide, and you seal
it inside the tooth. And then you close the tooth up with this glass ionomer cement and you seal it. And basically, you
leave it for several days, up to a week — that’s why it’s called a walking bleach. And you don’t want the bleach to go
down the root — that’s why you put the cover over the top of the root canal. And then you walk around for a few days, up
to a week. Usually it works very quickly and very, very well. And you come back, the filling that was put over the bleach
is removed, and then the tooth is filled permanently. And it does last for a number of years — it can be permanent. In
some cases you can get some discolouration again, for reasons that aren’t fully known, and then you can repeat the
internal bleach. It’s not a terribly expensive procedure, and also a lot of the time the patient’s whitening all the other teeth
anyway, so they’ll have whitening trays, which is a benefit to using whitening trays, and then you can touch up that tooth
externally. On the cost — each repeat visit is only around about, I say only, it’s still a lot of money, but it’s better than
other treatment that sometimes patients get offered, which we’ll get to later. The first visit is around about 3,000 Rand. It
doesn’t take very long. It does include all the fillings, the drilling out the fillings, gloves, sterilisation, et cetera. And then
the additional visit, if needed, which isn’t always needed. And then, of course, the final filling. So in the end it can be two
appointments or three appointments. And yeah, in the end it comes to less than any other treatment that anyone could
offer you for their tooth. In South Africa, the fee would range anywhere from three or four thousand Rand up to about
nine thousand Rand for all the visits.
Eon Engelbrecht – E-Radio-SA (10:34 – 10:40)
Now, I also want to ask you, does it hurt, doctor, given that you are working inside the tooth?
Dr Clifford Yudelman – OptiSmile (10:40 – 11:08)
No, absolutely not. The nerve is gone and there’s nothing to feel. You don’t need anaesthetic. So some people feel a bit
odd that there’s something sitting inside your tooth, but you can’t really feel it. Yeah — it’s much better than getting your
tooth drilled down for a crown, which we’ll talk about shortly. And you know, you get a lot done, but not much happens.
It’s quite straightforward.
Eon Engelbrecht – E-Radio-SA (11:09 – 11:17)
And we just spoke about internal bleaching. I want to ask you, is it safe, or can it damage the root from the inside?
Dr Clifford Yudelman – OptiSmile (11:17 – 13:01)
So yes, it is safe when it’s done properly, and it has to be done properly. It used to be that you could get external
resorption, meaning the outside of your root could start resorbing or getting damaged, if the bleach leaked past the root
filling. Once we dentists figured out that you actually have to seal the tooth properly — you really want someone who’s
wearing loupes or using a microscope, and who knows how to do it. If you’ve got someone who’s just out of community
service and they’ve never done it before, maybe it’s time to see an endodontist or a more experienced dentist — but it’s
quite a simple procedure if someone does follow the instructions. So for those of you listening who are just out of
community service, and you were at that lecture or did one at dental school, then you’re good to go. But if you don’t
know what you’re doing, then please don’t do it. Make sure — ask the dentist, how many of these have you done? So, me
personally, I don’t do any root canals at all. I’ve always referred my root canals out, when I was in Australia and America.
And since I’ve been at OptiSmile, I’ve got three dentists here who are very good with root canals — one of them actually
teaches root canals. And if you’re my patient and you need internal bleaching, or a single tooth bleach, then I book you in
with one of those dentists and they do it. So when I say it’s easy — do as I say, not as I do. That’s a little disclaimer.
Okay.
Eon Engelbrecht – E-Radio-SA (13:01 – 13:11)
And doctor, I think a lot of people want to ask us now, how long does it last? And, big question, will the tooth eventually
go dark again?
Dr Clifford Yudelman – OptiSmile (13:11 – 14:03)
Yeah, we sort of covered that already. Sometimes it will last for years, or in some cases forever, or at least until you pass
away — but your teeth age, and it can drift back slightly, or your teeth around it can actually get darker, and the one that
was bleached internally can look too light. And then you just touch it up with trays, or you get another quick internal
bleaching. It’s much better than getting a crown, which is often the only treatment that is offered — I want to say sold,
because it is basically sold to a patient as something that, in many cases, is unnecessary. We’ll get to that — I think it’s
your last or second-last question.
Eon Engelbrecht – E-Radio-SA (14:04 – 14:10)
And how many visits does it take, and how long before the colour actually matches?
Dr Clifford Yudelman – OptiSmile (14:11 – 15:13)
So like I was saying, it’s a few short, fairly short and easy appointments. The most important thing is, like I said before,
to make sure — on x-ray, and even with a CBCT, a 3D x-ray — that the root filling is completely sound. And also, when
it’s being done, that they use magnification, and that they see the coronal seal of the root canal is properly sealed. And
you don’t want to put bleach on a leaking root canal. And then they clean it out, put the material in, and then look at the
colour under daylight. You come back, check it again with some photos and a shade guide. And then we remove the
bleach, and then we put in a final restoration. And normally, as I said, it can look good very quickly — sometimes in
three or four days.
Eon Engelbrecht – E-Radio-SA (15:13 – 15:22)
Well, that’s very nice to know. And then I also want to ask you, if the tooth is dark, why not just simply fit a veneer and
be done with it?
Dr Clifford Yudelman – OptiSmile (15:23 – 17:08)
So look, a veneer always means drilling away healthy enamel, and once you’ve drilled away enamel, you can’t buy it
back. A veneer to block out a dark tooth almost never, ever works, because a properly done veneer is usually half a
millimetre thick, and it will be translucent, to let through the colour of the underlying tooth. So if you’ve got one tooth
that’s dark, and a dentist says we’ll put a crown or a veneer on there, you can be sure that it’s going to be a very opaque,
very white veneer. And then you’ve got the opposite problem — you’ve got that one white tooth in the front. And some
dentists will say, oh, we’ve got to veneer your two front teeth — that’s the most common answer. So, you know, you’ve
got a tooth that needs a quick walking bleach from someone who knows what they’re doing. It’s simple. And you leave
with two veneers instead. And sometimes people say — these dentists will tell people they need six veneers, or ten
veneers, so that all the teeth will match, and then they drill away all the teeth. And that’s the one thing that this podcast
stands against. That’s the thing that actually inspired me to call it Save Your Money, Save Your Teeth, and wherever
possible to talk out about that type of treatment. A veneer never solves a problem beautifully, and it messes up your teeth.
And, you know, like my late dad, who practised for fifty-seven years, I took a simple rule from him, and that’s: do
something that’s reversible, or that doesn’t damage the teeth. You know — don’t do it.
Eon Engelbrecht – E-Radio-SA (17:08 – 17:17)
And just one more question for today, doctor. What does internal bleaching save a patient compared with a ceramic
crown?
Dr Clifford Yudelman – OptiSmile (17:17 – 20:23)
Well, it saves your tooth. And aside from cost — if you have a root canal on a front tooth, for instance, and often we’re
talking about a front tooth, because if it’s a back tooth you’re probably not going to bleach it — some dentists will
completely over-diagnose it. They’ll tell you you need a post, which these days is very rare, and then they’ll put a screw
in your tooth, or glue in a fibreglass post, and then fill your tooth. And then they’ll file away 60% of your tooth for a
crown, and then cement a crown over this post and filling, after removing most of your enamel. And there’s a good
chance, especially if it’s a side front tooth — a lateral incisor — with a post, there’s a good chance that it will snap off at
the gum line in the future. And we call those a future implant. If I ask a dentist, what do you call a side front tooth, a
lateral incisor — if you’re in America, it’s tooth number seven or ten, in the rest of the world it’s one-two, or two-two —
not your very front tooth, but the one off to the side. If someone does a post and then a crown, you can be sure you’re
going to lose that tooth at some point — sometimes in five years or less, but they don’t last. And so don’t do that. And if
you do get a crown in your twenties, you’re going to need a replacement in five, or ten, or even fifteen years’ time. And
then you’re going to need another replacement. And it’s going to cost you a fortune long-term, because crowns are quite
expensive today, especially if you’re doing a single crown that’s going to match all your other teeth. And it takes a very
good dentist to do a single crown and match the other teeth. Imagine what that crown is going to cost you in ten years’
time — and then again in twenty years’ time. So the cheapest dentistry over a lifetime is almost always — in fact, is
always — the dentistry that is minimally invasive and takes the least away. At worst, with internal bleaching, you might
need another one in five years’ time or whatever — you’ve still got all of your tooth. And sometimes these teeth that have
had root canals, and that look dark, all that you have is that shell of enamel on the outside, but the enamel is the strong
part of the tooth. And if it gets built up with something called Ever-X, which is a Kevlar-fibre-reinforced filling material,
after the bleach the dentist fills it with that, your tooth is back almost to its original strength. So there’s really no need to
put a crown, or even a veneer, on a tooth — a single tooth that has gone dark. And that is, like I said, something that we
really stand against. That is what got us going with this podcast in the first place.
Eon Engelbrecht – E-Radio-SA (20:23 – 20:48)
And that’s it for another week’s edition of Save Your Money, Save Your Teeth. And I think one thing to take away is that
a dark tooth is a colour problem — it’s not always a damage problem. So before anyone reaches for a drill, just ask
whether it can be treated from the inside first. Enamel is the one thing in your mouth that you cannot buy back. Dr
Yudelman, thank you so much.
Dr Clifford Yudelman – OptiSmile (20:48 – 20:52)
Thank you. And looking forward to next week.
Eon Engelbrecht – E-Radio-SA (20:53 – 21:04)
Absolutely. Likewise. And until next time, thanks also to our listeners for joining us. Look after your teeth, and also look
after your money. Until next time.
OptiSmile Announcer (21:24 – 22:08)
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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.
