Sensitivity to cold is information, not just an annoyance

Sensitive teeth are so common that most people treat them as a personality trait rather than a symptom. Usually that is fair enough — a lot of sensitivity is harmless and manageable. But the character of the pain tells you which kind you have, and the difference matters, because one kind can wait and the other decides whether a tooth is saved or lost.

What sensitivity actually is

Under the enamel is dentin, and dentin is not solid. It is threaded with thousands of microscopic tubules running from the outer surface inwards to the nerve. When the enamel covering them is worn through, or the gum that covered the root has receded, those tubules are open to the mouth.

Cold, heat, sweetness or even a puff of air then causes tiny fluid movements inside those tubules, and the nerve reads that movement as a sharp, brief pain. That is why classic sensitivity is immediate and short — it starts the instant the trigger arrives and stops within seconds of it going away.

Why the enamel wore through

• Brushing too hard, particularly with a horizontal scrubbing motion, which wears a notch at the gumline where enamel is thinnest.
• Acid erosion from fizzy drinks, citrus, wine, vinegar — or from reflux, which does the same thing from the inside and often at night.
• Gum recession, which exposes root surface that never had enamel over it in the first place.
• Grinding or clenching, which flattens the biting surfaces and flexes the tooth at the neck.
• A crack, which can be invisible and typically hurts on releasing a bite rather than on pressing down.
• Recent treatment or whitening, which commonly causes temporary sensitivity that settles over days to a few weeks.

What usually helps

For ordinary dentin sensitivity, a fair amount can be done at home, and it is reasonable to try for a few weeks before assuming something is wrong.

• Use a desensitising toothpaste and give it time. These work either by calming the nerve or by plugging the tubules, and they need a few weeks of consistent use — not one application. Do not switch every week.
• Smear it on the sensitive spot with a fingertip before bed and do not rinse. This is more effective than brushing with it alone.
• Switch to a soft brush and lighten up. Continuing to scrub hard will outpace anything the toothpaste is doing.
• Cut the acid frequency. It is how often, not how much — sipping one fizzy drink across an hour is worse for enamel than drinking it in five minutes.
• Do not brush straight after acidic food. Wait about thirty minutes; the enamel is temporarily softened.
• Mention grinding if you wake with a tight jaw or headaches. A night guard is a simple fix that prevents a lot of future work.

The pain that means something else

Everything above concerns short, sharp sensitivity. A different pattern points to the nerve inside the tooth being inflamed or infected, and that does not resolve on its own — it progresses.

What a dentist can do that you cannot

For stubborn but ordinary sensitivity there are in-clinic options that work faster than toothpaste: a high-concentration fluoride varnish, a sealant or bonding over an exposed notch, or occasionally a gum graft where recession is severe. Where a crack or decay is the real cause, treating that is what stops the sensitivity — no toothpaste will.

The examination is the useful part regardless. Sensitivity has half a dozen possible causes that feel broadly similar to the person experiencing them and look quite different on inspection and on an X-ray.

This is general guidance, not a diagnosis. If a tooth is hurting, have it examined rather than working from an article.