What causes enamel erosion?

Fig. 1 — Same tooth, two different diseases. On the left the acid is made on the tooth, under a pad of plaque, and the damage starts below a surface that is still intact. On the right the acid arrives ready-made and washes across everything, so the surface itself goes; the dashed line is where the enamel used to be. Cleaning your teeth prevents the left-hand panel and does almost nothing about the right-hand one — which is why the standard advice fails here. Diagrammatic, not to scale.

Enamel erosion is enamel dissolved by acid that arrived already made — in a drink, in food, or from the stomach. That makes it a different problem from tooth decay, where the acid is manufactured on the spot by bacteria living in plaque. Almost everything written about erosion blurs the two, and the blurring is expensive, because the advice that solves one of them barely touches the other.

Erosion is not decay

Decay is a bacterial process. Bacteria in dental plaque ferment sugar into acid, that acid works on the enamel directly underneath the plaque, and the damage begins beneath a surface layer that stays intact for a while. The full cycle — how the mineral comes and goes, and where the line between reversible and not falls — is set out in can teeth remineralise? and is not repeated here.

Erosion needs no bacteria at all. The acid is already acid when it reaches your mouth. It washes over whatever it touches, so the damage is broad rather than localised, and it works from the surface down rather than from underneath.

The practical consequence is the thing readers get wrong. You cannot brush or floss your way out of erosion. Plaque control is the answer to very nearly every other dental question, and here it is close to irrelevant — you can have immaculate hygiene and significant erosion at the same time. Clinicians now tend to say erosive tooth wear, because in a real mouth chemical dissolution and mechanical wear arrive together.

Where the acid comes from

England’s national prevention guidance splits it in two: extrinsic acid, from food, drink and medications, and intrinsic acid, from the stomach — reflux, rumination, vomiting and eating disorders — or a mixture of both.

Source	Where it turns up	What addresses it
Acidic drinks	Colas and other soft drinks, sports and energy drinks, fruit juice, flavoured sparkling water, wine and cider	Contact time and how you drink it, more than quantity
Acidic food	Citrus, vinegar and dressings, pickles, some fruit eaten slowly or often	Keeping it to mealtimes where possible
Reflux	Gastro-oesophageal reflux, and the “silent” kind that produces no heartburn at all	A doctor. Treating the teeth without treating the reflux achieves nothing
Repeated vomiting	Pregnancy sickness, some medical conditions, eating disorders	A doctor, plus a dentist for the damage
Medications	Chewable and effervescent preparations that are themselves acidic; separately, anything that dries the mouth	Ask about acid-free alternatives

Two notes on that last row. A dry mouth makes every other source worse, because saliva is what clears and neutralises acid in the first place — see what causes dry mouth. And erosion is a recognised sign of both reflux and of repeated vomiting, including in eating disorders; if that applies to you, it is a conversation to have with a doctor, who can help with the cause rather than the symptom.

What it looks like

Erosion is easy to miss, for a reason worth understanding: it is gradual, and it happens to every affected tooth at once. There is no single day when something changes, and no asymmetry to catch your eye in the mirror.

Thinning and translucency at the biting edges of the front teeth, which can start to look glassy or grey where the enamel has thinned enough to stop being opaque.
Cupping on the molars — small dished hollows worn into the cusps, often with a rim of enamel still standing around them.
Teeth looking yellower. Not staining. The dentine underneath is naturally darker, and a thinner enamel layer simply shows more of it.
Sensitivity, as enamel stops covering the dentine — why exposed dentine hurts is a page of its own.

Dentists grade this with a specific tool rather than by impression: the Basic Erosive Wear Examination. The mouth is divided into six sextants, the worst surface in each is scored from 0 to 3 — 0 none, 1 an initial loss of surface texture, 2 a distinct defect affecting under half the surface, 3 more than half — and the six scores are added up. It exists so that wear can be tracked over years rather than argued about, which matters for a condition this slow. A score of 3 in every sextant is taken as a signal for further investigation.

The sparkling water question

It deserves a straight answer rather than a scare, and the straight answer has two halves.

Plain, unflavoured sparkling water is not the problem. Carbonation makes water mildly acidic, but still and carbonated bottled waters both sit close to neutral, and in a study the American Dental Association reports on donated extracted teeth, sparkling water and ordinary laboratory water had about the same effect on enamel. In research on the “alternative soda” trend that the ADA publicised in 2022, the only drinks that did not erode enamel at all were non-carbonated, unflavoured bottled waters — but flavoured sparkling waters and both sugary and sugar-free sodas all did, and the finding was that the acid, not the sweetener, was doing the eroding.

Flavoured sparkling water is a different drink. The flavouring usually brings citric or other fruit acids with it, and the measurements are not close. One laboratory study of flavoured waters found them at pH 2.64 to 3.24, against an orange juice control at 3.68, and after an hour’s immersion they removed between 1.18 and 6.86 microns of enamel — the orange juice removed 3.24. Several of them were worse than the juice. A separate study of flavoured sparkling waters found erosive potential between 89% and 143% of pure orange juice, and concluded that they should be treated as acidic drinks rather than as water with flavouring.

The two sit side by side on the same shelf, in the same kind of can, and are treated as one product. Only one of them behaves like fruit juice.

So the ordering, from primary measurements: plain still water, then plain sparkling water at roughly the same place, then flavoured sparkling water in the same territory as juice, then soft drinks. What moves a drink along that scale is added acid rather than bubbles — and after that, how long it stays in contact with your teeth.

Why brushing does not prevent it — and what happened to the 30-minute rule

The first half of this is solid and is the whole point of the figure above. Brushing and flossing remove plaque; plaque is not involved in erosion; so the single most reliable piece of dental advice there is does not prevent this particular problem. It is worth doing for every other reason, and it will not save your enamel from acid.

The second half is the bit almost every article gets wrong, and we had it wrong on another page until we checked.

You will have read that you must wait half an hour before brushing after anything acidic, because acid softens enamel and brushing then scrubs the softened layer away. The rule has a real origin: laboratory and in-mouth appliance studies did show softening, and a 2003 study concluded that at least 30 minutes should elapse before brushing — that one was about dentine, not enamel.

Then it was tested properly.

A 2020 systematic review and meta-analysis pooled six studies on human enamel and found delaying brushing by 30 to 60 minutes was not better than brushing immediately. Its conclusion was that delayed brushing after an erosive attack was not effective at reducing erosive wear — while noting the underlying studies were laboratory and appliance-based, not clinical, and that trials are still needed.
The one clinical dataset points the same way. A 2017 case-control study of hospital patients found that brushing within ten minutes of acid intake was not associated with erosive tooth wear once diet was accounted for.
A 2024 scoping review concluded that brushing with fluoride toothpaste immediately after an erosive challenge does not increase the risk, and can be recommended.
England’s national prevention guidance states it flatly: there is no strong evidence that the timing of toothbrushing is of great importance.

If you already wait, waiting harms nothing. But it is not the lever it is sold as, and it has been crowding out the thing that does work. Missing your fluoride toothpaste in order to obey the rule would be a straightforwardly bad trade.

The one place the advice still stands

After vomiting. Official guidance is not to brush — rinse the mouth with water instead, and if you want the taste gone, apply fluoride toothpaste with a finger or use a fluoride mouthrinse.

Stomach acid is far stronger than anything in a drink, and this is the situation the original concern was really about.

What actually reduces erosion

The most useful evidence here comes from a study of actual patients rather than enamel blocks, and its findings are about how people consume acid rather than how much.

Fruit eaten between meals was associated with erosive wear; the same fruit eaten with meals was not. Acidic drinks were associated with wear whatever time they were drunk. And two habits stood out as strongly as having acid three or more times a day: taking more than ten minutes to eat fruit, and sipping, swishing or holding a drink in the mouth before swallowing.

Stop nursing acidic drinks Sipping one over an hour is worse than drinking the same thing in five minutes. This is the single most changeable habit in the evidence, and it costs nothing.
Do not swish or hold it in your mouth Whatever the drink, swallow it rather than tasting it repeatedly on the way down.
Keep acidic food to mealtimes For fruit, the timing was the whole difference between an association and none.
Follow it with water Plain water alongside or afterwards dilutes and clears the acid. Do not scrub — just rinse.
Use fluoride toothpaste twice a day, and spit rather than rinse This is the best-evidenced protection available to you, and it matters more here than the timing of it. Remineralising agents come up on the hydroxyapatite toothpaste page.
If the acid is coming from your stomach, treat that A dentist can repair worn teeth. Only a doctor can stop them being worn away again.

A straw is often recommended for acidic drinks, on the logic that it reduces contact with the front teeth. That follows sensibly from everything above, though we found no study testing straws against erosion specifically — treat it as a reasonable extension of the contact-time principle rather than a proven measure. Chewing sugar-free gum afterwards raises saliva flow, which is the body’s own clearance system; the case for xylitol specifically is weaker than its marketing, but the chewing itself is genuinely useful.

What has been lost is lost

Enamel is not living tissue. The cells that made it are gone once the tooth has come through, and nothing regrows it. Enamel that has been softened can take mineral back from saliva and reharden; enamel that has physically dissolved away does not come back. That is the same boundary drawn in detail on can teeth remineralise?, and it applies here unchanged.

What a dentist can do is stop the progression and, where the wear is significant, rebuild the shape and cover exposed dentine. Doing that early is both simpler and cheaper than doing it late, which is the argument for noticing.

When to see someone

Book an appointment for edges that are thinning or turning translucent, dished hollows on the biting surfaces of molars, teeth that keep looking yellower, or sensitivity that is getting worse rather than settling.

See a doctor as well as a dentist if there is any suspicion of reflux — including reflux with no heartburn, which is common and is exactly the kind that goes untreated for years — or if vomiting is happening regularly for any reason. If that includes an eating disorder, please talk to a doctor; it is treatable, and the dental damage is a reason to get help rather than a reason to put it off.

The reason to go rather than watch is that erosion is slow, symmetrical and painless until late. A dentist comparing against records from two years ago will see it long before you do — and this is a problem where the cheap intervention and the expensive one are separated mostly by how early you turn up.

One thing this page will not hand you: oral probiotics have no bearing on erosion. Whatever the evidence says about managing the bacteria in your mouth — and we have gone through one heavily advertised product in detail — erosion is not a bacterial process, so that entire category is beside the point here.