A dental hygienist explains: 5 reasons your breath keeps coming back, even though every check-up says your teeth are perfect

Every few weeks somebody sits in my chair, gets told everything is fine, and leaves knowing perfectly well that nothing has been solved.

I have been on the other end of that conversation for fifteen years. Here is what is actually going on.

1.Your teeth were never the problem, and your dentist was never wrong

Here is the whole check-up. Every tooth, marked one at a time on a little map of your mouth. Your gums, scored part by part with a thin metal probe. A look at the soft bits. Then we book you back in.

That is everything that gets written down. Now find the line about the bacteria living on your tongue. There isn't one. Not a box, not a score, nowhere to put it.

So "everything looks fine" is true, and it answers nothing. Nobody was checking the part that smells.

If you would rather skip ahead, the solution I recommend now is this.

2.We do look at your tongue. We are looking for cancer, not for this

Most articles say nobody looks at your tongue. Wrong, and a good reason to ignore them.

I look at it at every appointment. Stick it out, left, right, lift it up. Then your cheeks, the roof of your mouth, your throat, the glands in your neck. Two minutes, and it is one of the most important things I do all day, because it is a cancer check. An ulcer that has not healed. A patch that will not wipe away. A lump.

A layer of bacteria is none of those things. So I look straight past it. I have looked directly at the cause of your bad breath thousands of times, looking for something else.

Nobody has ever checked the one place it comes from, this is the lozenge my patients use.

3.You cannot smell your own breath, so you have never once known where you stand

The cruel part, and almost nobody says it out loud: you cannot smell your own breath. Not sometimes. Ever. Your nose sits a few centimetres above your mouth and switches off to your own smell within seconds, then keeps it switched off.

So the cupped hand in the car has never given you a real answer. It physically cannot. And nobody else is going to tell you, because who would.

That is why this drags on for years. No way to know if it is bad today, no way to know if anything is working. You never stop checking and you never get an all clear.

So stop smelling and start looking. Tonight: phone torch, bathroom mirror, tongue out as far as it goes, look at the back third. Whitish film, thicker at the back. Take a photo. Then another every Sunday. Nothing changes day to day. Week one against week four is where you see it.

That photo will be the first honest answer you have ever had about this that does not depend on reading somebody's face.

If you are sick of never knowing, this is what I started recommending.

4.Everything you have tried takes it off. None of it changes what grows back

Brushing, scraping and rinsing all do one job: they take bacteria off. They do not change which bacteria come back, and on the back of your tongue they are back within hours. That is why you brush after breakfast and taste it again by lunch. Nobody told you that was normal, so you decided you were doing it wrong.

Strong mouthwash is worse. It cannot pick and choose, so it kills the smelly bacteria and the good ones holding them down, and the smelly ones regrow faster into the cleared ground.

"Twenty fresh minutes, then worse than before you rinsed. I stopped recommending it two years ago, having recommended it for the eleven before that."

If your shelf has three mouthwashes on it, this is what I would buy instead of a fourth.

5.The only thing that works is changing who lives in those cracks

The back third of your tongue is not smooth. Magnified, it is thousands of small fleshy spikes packed tight together, like the pile of a carpet, with deep narrow cracks between them. Almost no air gets down there, and the bacteria doing this to you cannot survive where there is oxygen. That is why they live in those cracks and not on the flat pink part at the front. You have been cleaning the part you can reach. They are in the part you cannot.

Down there they feed on protein and give off hydrogen sulphide, the rotten egg smell, and methyl mercaptan, the rotting cabbage one. Those two are roughly ninety per cent of what other people smell.

"You cannot empty a carpet. You can only change what lives in the pile."

A scientist called John Tagg worked out why some children never caught the sore throats going round their school: they carried a bacteria, Streptococcus salivarius, that got into the cracks first and would not give them up. It even makes two compounds of its own, salivaricin A2 and B, that hold down everything around it. He called the strongest strain K12. The bad breath part turned up later, by accident.

Which is why it goes in at night. Saliva rinses those cracks all day and all but stops while you sleep, which is why mornings are worst. K12 goes down last thing, into cracks you have just cleaned, at the hour the other side normally runs unopposed. You are not killing anything. You are changing who is standing there when the lights go out.

You can buy K12 over the counter now, in quite a few different products, and most of them get it wrong. So before you buy any of them, check three things.

A lozenge you suck, not a capsule you swallow. A capsule goes straight down to your stomach. This needs to dissolve slowly in your mouth, on the surface the problem is actually on.

K12 and M18, both of them. K12 is the one from the throat research above. M18 is a second one from the same collection, the one that has been looked at for gums.

One at night, after you brush. For the reason above. Anything you take in the morning is working the shift where saliva is already doing the job for you.

The one I point people at is Virae's oral probiotics: K12 and M18 in a slow dissolving lozenge, six billion live cultures, one a night.

What I would do tonight

Here it is, without the padding.

Order it now, while the buy one get one free is on. The bigger packs come with the tongue scraper thrown in. It arrives in plain packaging, nothing on the box or the receipt says what it is for.

The night it arrives, take the day one photo. Phone torch, mirror, tongue out, back third. Then one lozenge after brushing, last thing, every night. That is the whole routine.

Check the photo again each Sunday. Somewhere between week one and week four you will see the coating fading. That is where most people quit, and it is the one mistake: those cracks go straight back to whoever gets there first. Keep going to sixty nights.

If nothing has changed by night sixty, email them. They refund you, and you keep the scraper.

And at your next check-up, somebody will ask you to stick your tongue out. For the first time in years, they will be looking at a different mouth.

That starts tonight, after you brush.

Start your 60 nights →

I still tell people everything looks fine several times a day, and it is still true. Your teeth are fine. Your gums are fine.

It was never your teeth.