Sensitive teeth: what's causing it, and what actually helps

What sensitivity actually is

Enamel is the hard outer shell of a tooth, and it has no nerve supply at all. Underneath it sits dentine, which does. Dentine isn't solid. It's threaded with thousands of microscopic tubes running from the outside of the tooth inwards towards the nerve, and every one of those tubes is filled with fluid. When dentine is exposed, cold, sweetness, air and sometimes just touch make that fluid shift, and the nerve reads the movement as a short, sharp zing.

That's why sensitivity has such a recognisable pattern. The pain arrives fast, feels electric rather than dull, and stops within a second or two of the trigger going away. It also explains why the treatments work the way they do. Block the tubes, or cover the exposed dentine, and the message stops getting through.

Hold on to that description, because it's the one useful test you can do at home. Pain that fades the instant the cold goes is ordinary sensitivity. Pain that hangs around after the trigger has gone is telling you something else, and we'll come back to that near the end.

Receding gums and exposed roots

The most common reason dentine ends up exposed is that the gum has moved. Roots aren't covered in enamel. They have a much thinner, softer layer called cementum, which wears away easily once it's out in the open. So the moment a gum recedes even a millimetre or two, sensitive root surface is sitting there in the path of every cold drink.

Gums recede for two main reasons. Gum disease destroys the attachment and the bone underneath, and the gum follows it down. Or the gum gets scrubbed back over years by a hard brush, heavy pressure and a sawing motion, often alongside a small notch worn into the tooth right at the gumline. Plenty of people have a bit of both.

Which one it is matters, because the treatment is different. Active gum disease needs the disease treated first, otherwise the recession keeps going. Brushing damage needs the technique changed, and often a small tooth-coloured filling to seal the worn notch. Neither is complicated, but guessing between them tends to waste years.

Worn enamel, and the acid behind most of it

Enamel doesn't usually wear out from chewing. It dissolves. Acid softens the surface, and once softened it gets brushed and rubbed away, a little at a time, until the dentine underneath starts showing through. Teeth that have eroded often look slightly yellow, feel smooth or glassy at the edges, and go sensitive across several teeth at once rather than in one spot.

The usual sources are familiar: fizzy drinks including the sugar-free ones, energy and sports drinks, citrus, wine, cordial, kombucha, and cider vinegar taken as a health habit. Reflux does the same job from the inside, and so does repeated vomiting. What matters most is frequency, not volume. A can of soft drink with lunch is one acid hit. The same can sipped over three hours at a desk is closer to a constant one.

The other half of the problem is timing. Brushing straight after acidic kai or drinks scrubs enamel while it's still soft. Rinse with plain water, wait about half an hour, then brush. That single change does more for worn enamel than most of the products sold for it.

Grinding and clenching

Night grinding is easy to miss, because the person doing it is asleep. The clues turn up elsewhere: a tight or tired jaw in the morning, headaches around the temples, teeth that have gone flat across the biting surfaces, or a partner who's mentioned the noise. Daytime clenching is quieter still, and often shows up in people who are stressed, concentrating hard, or on long shifts.

The load involved is much higher than normal chewing, and it does two things to sensitivity. It grinds through the enamel on the biting surfaces until dentine is exposed in small polished patches. And it flexes the tooth at the neck, which contributes to those wedge-shaped notches at the gumline and can start fine cracks in the enamel.

A custom occlusal splint, made from a mould of your teeth and worn at night, takes the wear instead of your teeth. It doesn't stop the grinding, and it isn't meant to. It just puts something replaceable between the two arches, which is a far better outcome than replacing worn teeth later on.

Whitening sensitivity, and why it passes

Whitening gel makes teeth temporarily more sensitive in a large share of people. Peroxide passes through enamel and briefly irritates the nerve inside the tooth, which is why the zings often peak in the day or two after treatment and then fade. It settles on its own and it doesn't cause lasting damage to healthy teeth.

If you already have sensitive teeth, say so before you start rather than after. There's a lot that can be planned around it: lower gel concentrations, shorter wear times each day, spacing sessions further apart, and using a desensitising toothpaste for a fortnight beforehand and throughout. Most people who struggle with whitening struggle because nobody set it up this way.

One thing worth being firm about: whitening over untreated decay, a leaking filling, exposed roots or inflamed gums hurts, and no amount of technique fixes that. That's the reason the check comes first every time.

When sensitivity is a signal, not a nuisance

Ordinary sensitivity is annoying but harmless. Some patterns aren't, and they're worth knowing so you don't sit on them for months. If any of these sound like yours, book in rather than buying another toothpaste.

1. 1/Pain that lingers more than a few seconds after hot or cold has gone. That suggests the nerve inside the tooth is inflamed, often from deeper decay or a crack.
2. 2/A sharp jolt when you bite down on something, or when you release the bite. That's the classic pattern of a cracked tooth, and it usually involves one specific tooth you can point to.
3. 3/Pain that starts on its own, throbs, or wakes you at night. Nerve infections don't settle by themselves, because they've nowhere to drain.
4. 4/Hot drinks causing pain that cold water actually relieves. Unusual, but a well-recognised sign that the nerve is dying.
5. 5/Sensitivity in one tooth that's steadily getting worse, especially alongside a bad taste, a lump on the gum, or any facial swelling.

What genuinely helps at home

Desensitising toothpaste does work, but most people use it wrong. The active ingredients need contact time, so after brushing, smear a little extra straight onto the sensitive spot with a clean fingertip and leave it there. Spit out the excess and don't rinse with water afterwards, at night especially. Give it two to four weeks before deciding whether it's helping, because it builds up rather than working on the first go.

Alongside that: switch to a soft brush and hold it lightly, brush along the gumline rather than scrubbing across it, keep acidic drinks to mealtimes instead of sipping all day, and leave half an hour between anything acidic and brushing. If reflux is part of the picture, treating the reflux is part of treating the teeth.

What we can add in the chair is the rest of it: fluoride varnish on the exposed areas, sealing worn dentine with bonded material, small fillings in gumline notches, treating gum disease so recession stops progressing, and a splint if grinding is doing the damage. A consult is $60, or $79 for a new-patient exam including X-rays, and you'll get a written quote before anything gets started.

Quick questions

Does sensitive toothpaste actually work, or is it marketing?

It works for most people with ordinary sensitivity, provided it's used properly. Rub a little onto the sensitive area after brushing, don't rinse it off, and give it two to four weeks. If there's no change by then, something else is going on and it's worth an examination.

I've had sensitive teeth for years. Is it too late to do anything?

No. Recession and enamel wear don't reverse, but the sensitivity itself usually responds well to sealing the exposed surfaces, fluoride treatment and small fillings where needed. Long-standing cases are some of the most satisfying to sort out.

Will whitening leave my teeth sensitive for good?

Whitening sensitivity is temporary and settles within a few days. If you're already sensitive, tell us beforehand so we can use gentler concentrations and shorter wear times, and prepare the teeth first.

What will it cost to find out what's causing mine?

A consult is $60, and a new-patient exam with X-rays is $79. You'll leave knowing what's causing it and what the options are, with a written quote before any treatment starts.