Rotten Teeth: Can They Be Fixed, and What Has to Come Out?

If you've been standing at the mirror with your lip pulled back, looking at a tooth that's gone dark and crumbly, quietly totting up how much of your mouth you're about to lose, let's take the worst version of that off the table right now. The half of a tooth that decides whether it can be saved is the half you can't see from where you're standing.

The Half of the Tooth You Can't See Is the Half That Decides

Rotten is the word nearly everybody uses, and we know exactly what you mean by it: dark, soft, chipping away at the edges, catching your tongue every time you forget not to touch it.

So here's the thing that surprises most people who come and sit in our chair. A tooth comes in two halves. There's the crown, which is the white part above the gum that does the chewing and turns up in the photographs. And there's the root, a long anchor buried in your jawbone, which is what actually holds the tooth in your head. Decay begins at the surface where plaque sits, and it works inwards from there, so it eats away at the crown first, and it usually spends years doing that before it gets anywhere near the anchor underneath.

Picture an old tree standing in a field. The trunk can be split, hollowed out and gouged by forty winters, and the tree stands there perfectly happily, because what keeps a tree up is underground. Teeth work the same way. A tooth can lose a great deal of its visible top and still be firmly anchored, still alive, and still very much worth keeping, because the part doing the holding was never touched.

Which is why the tooth that looks most alarming in a bathroom mirror is very often one of the more ordinary repairs there is.

The Two Questions a Dentist Is Really Asking

When a dentist looks at a rotten tooth, two questions decide everything that follows, and how bad it looks is not one of them.

The first question is whether there's enough solid tooth left to build on. Any repair has to hold on to something, and a crown, which is the cap that goes over a rebuilt tooth, grips it rather like a ring grips a finger: it wants a continuous band of firm tooth all the way round to hang on to. So a dentist runs a probe gently round the edges, feeling for where the soft decayed tooth stops and the hard healthy tooth starts. If that band is still there above the gum, even a modest one, the tooth has somewhere to anchor a repair and can almost certainly stay. If the decay has run down below the gum the whole way round, there's nothing left to hold on to, and that's the point where a tooth stops being restorable.

The second question is whether what sits underneath is still healthy, and there are two things down there worth checking.

One is the nerve. Deep decay that has reached the nerve in the middle of a tooth sounds like the end of the story, and it usually turns out to be the middle of it. Think of the nerve as an old cable threaded through a narrow channel inside a wall. When the cable has had it, nobody takes the wall down. You draw the dead cable out, clean the channel, fill it and seal the top, and the wall stands exactly as it stood before. That's a root canal in one breath, and it's the reason a great many teeth that looked finished get to stay.

The other is bone. Your teeth sit in bone the way a fence post sits in ground, and long-running gum disease slowly washes that ground away. A tooth with a perfect crown and no bone left around it feels loose, and loose is the one thing no repair can put right, because there's nothing solid left to build from. That's a separate problem with its own treatment, set out on our gum disease treatment page.

Why "They'll All Have to Come Out" Almost Never Happens

This is the sentence people arrive braced for, and it's worth saying plainly that it's very rarely the one they hear.

The reason is simple enough. Decay is a local event. Each tooth has its own grooves, its own contact points and its own history, so teeth in the same mouth arrive at wildly different places. That's why a mouth that hasn't been looked at in years almost always comes back as a mixture: a good number of teeth that need nothing at all, a few that need small fillings, one or two that need something bigger, and now and then a single one that has genuinely run out of road.

There's a second reason, which is that keeping a tooth is nearly always the better outcome. Each tooth is doing a job. It holds its neighbours upright, it shares the chewing load so no single tooth takes a hammering, and its root keeps the jawbone around it busy and dense. Take one out and the rest quietly rearrange themselves around the gap. So the whole weight of the decision sits on the side of saving, and a tooth has to make a real case for itself before taking it out becomes the right answer.

If what's actually holding you back is how it will feel to open your mouth in front of a stranger, that deserves its own answer, and we've written it: bad teeth and embarrassed to see a dentist. And if it's been five, ten or twenty years since the last appointment, the whole road from the first visit to a settled mouth is laid out in going to the dentist after years.

Tooth by Tooth: What Yours Is Most Likely to Be

Most rotten teeth land in one of four places, so it's worth knowing which one you're looking at.

Three of those four get saved, and they happen to be the three people arrive most frightened of. A dark spot, a chalky patch or a small hole with nothing hurting is decay caught before it ever reached the nerve. A tooth that has lost a wall or a corner, where everything else still feels firm, still has plenty of solid tooth to build a repair onto. And a tooth that's been aching, or has woken you at two in the morning, or has slowly gone grey next to its neighbours, is a tooth with its nerve involved, which sounds like the end and hardly ever is. What each of those takes to put right, from a filling up to a root canal with a crown over the top, is walked through with the price beside it in our guide to the stages of tooth decay and the fix at each one.

The fourth one is the tooth that's broken level with the gum, or wobbles when you push it with your tongue, or gives a sharp jolt when you bite on something hard. That's the group where extraction does come up, though even here the X-ray gets the final say, because a tooth broken at gum level on one side can still be solid all the way round the other.

When a Tooth Genuinely Has to Come Out

There are three honest reasons, and they're all about the tooth running out of something rather than about how black it looks.

The first is that there isn't enough solid tooth left above the gum for a repair to grip. The second is a crack that has travelled down into the root, because a crack lets bacteria in along its whole length and no filling can seal a split that deep. The third is bone: when gum disease has taken away most of the support around a root, the tooth is loose, and there's no repair that makes a loose tooth firm again.

When one of those is the answer, taking that tooth out is usually the kindest move for everything around it, because a tooth that keeps flaring up or collecting food in a crack is a standing source of trouble for its neighbours. Once it's out, the mouth settles. And if the side of your face is swollen, come in that day rather than waiting it out, because swelling calms down much faster once the cause has been dealt with.

The cost of that is its own question, and we've broken it down by type in tooth extraction cost UK.

What Goes in the Gap If One Does Come Out

This is the part people worry about most, and it splits neatly by where the tooth was.

A front tooth is going to want replacing, and quickly, for reasons that need no explaining. A back molar is a more open conversation. Some people replace them, some leave the gap and get on perfectly well, and which of those suits you depends on how many teeth sit behind it and how your bite comes together. Our guide to missing tooth replacement options weighs all of that up properly, including the option of leaving it alone.

There are three ways to fill a gap, and here's what each one is, with the price.

Those figures are guidelines for a straightforward case. The figure for yours gets written down and agreed with you at the consultation, before any work begins, and nothing is added to it later. Worth knowing before you rule anything out on the price: any treatment over £500 is eligible for 0% finance over twelve months, so the bigger options spread rather than landing in one go.

If dentures are the direction you're leaning, dentures cost UK goes through what drives the price and what's included.

The Real Answer Lives on the X-Ray

Everything above is the shape of the thing. The answer about your particular tooth lives about a centimetre below where you can see, which is precisely why an evening of squinting into a mirror never settles it.

A digital X-ray shows the root, the bone around the root, and how far the decay has travelled, all in a few seconds. That's the picture that turns "I think I'm going to lose it" into a straight yes or no. At UrgentCare Dental an appointment is £20, and that buys you a dentist going properly over the whole mouth, the digital X-rays if your tooth needs them, and a plan you can take away with you. If there's treatment to do, you get the exact price for it in writing before anything begins, and it happens that same visit only if you want it to. The appointments afterwards that check it has all settled don't cost anything, and every figure we charge sits openly on our pricing page so you can read it before you ring.

If you're dreading the appointment itself, say so when you book. Unhurried appointments, zero judgement, and a conversation before we pick anything up: that's how we work with people who've been away a long time, and sedation runs from a light tablet to take the edge off, right up to IV sedation where you're awake and deeply relaxed and often remember none of it.

And if the question underneath all of this is really about money, the honest arithmetic for a whole mouth after years away is set out in how much it costs to fix your teeth.

Common Questions About Rotten Teeth

Can a badly rotten tooth be saved?

Usually, yes. What decides it is how much firm tooth is left above the gum for a repair to grip, and whether the root and the bone around it are healthy, so a tooth that looks dramatic from the outside is often perfectly restorable. Even decay that has reached the nerve doesn't end a tooth, because a root canal clears the dead nerve out and the tooth carries on working. The teeth that can't be saved are the ones with nothing solid left to build on, a crack running down into the root, or too little bone holding them in.

Do rotten teeth always have to be pulled out?

No, and having the whole lot taken out is uncommon. Decay happens tooth by tooth, so mouths come back as a mixture of teeth that need nothing, teeth that need a filling, and usually only one or two that need something bigger. Keeping a tooth is also the better outcome wherever it can be done, because each one holds its neighbours upright and keeps the jawbone around it dense, so a tooth has to have run out of structure or support first.

How rotten is too rotten to fix?

The line falls at the gum. A repair needs a band of firm tooth to hold on to, so once decay has eaten below the gum line all the way round, there's nothing left for a crown or a filling to grip and the tooth can't be rebuilt reliably. The other two lines are a crack that has run down into the root, which lets bacteria in along its whole length, and heavy bone loss from gum disease, which leaves the tooth loose. Short of those three, there's usually a way to save it.

Does fixing a rotten tooth hurt?

The tooth is numbed first, so the work itself is felt as pressure and vibration rather than pain. A deeply decayed tooth that's already sore can take a little longer to go properly numb, and the answer to that is more anaesthetic and more time rather than pressing on. If nerves about the appointment are the real issue, we've set out the sedation options from the tablet that takes the edge off up to being deeply relaxed the whole way through.

What happens if a rotten tooth is left alone?

It carries on getting bigger, because decay doesn't stall or heal over. A small cavity that would take one appointment to fill grows towards the nerve, and once it reaches it the repair moves up from a filling to a root canal and a crown. Left longer still, the crown of the tooth crumbles past the point where anything can grip it, and the tooth that one appointment would have saved becomes the tooth that has to come out. That's the whole argument for coming in early, and it's an argument about cost more than anything dramatic.

Can a dentist tell whether a tooth can be saved just by looking?

Partly, and never completely. Looking and probing shows how much firm tooth is left above the gum, which answers half the question. The other half is the root, the bone around it and how deep the decay has travelled, none of which is visible from the outside, which is why a digital X-ray is taken before anyone gives you a verdict. It takes seconds, and it's the difference between a guess and an answer.

You Can Start With One Tooth

Here's the thing we'd most like you to take away. You don't have to arrive with a plan for your whole mouth, or a budget for all of it, or the courage for every appointment at once. You can come in with the one tooth that's been bothering you, find out exactly where it stands, and decide what happens next when you know.

That's what the appointment is for. We're open around the clock at all three practices, in Armley in Leeds, in Manchester, and on Main Street in Bingley for Bradford, and you can book a slot at whatever hour you happen to be reading this, including the one where you're still standing at the mirror.