1. Receding gums

The root of a tooth is not covered in enamel. When the gum recedes, that root surface is exposed, and it is far more reactive to cold. Recession comes from heavy brushing, gum disease, or simply years.

What helps: a softer brush and a lighter hand, treating any gum inflammation, and sometimes sealing the exposed root surface.

2. Acid wear

Soft drinks, sports drinks, citrus, wine and reflux all soften enamel. Brushing straight afterwards scrubs off the softened layer. Over time the enamel thins and cold gets through.

What helps: rinsing with water after anything acidic and waiting before brushing. If reflux is the cause, treating the reflux matters more than anything we do in the chair.

3. Grinding

Worn biting surfaces expose dentine, which contains thousands of tiny tubules running to the nerve. That is why the sensitivity often feels sharp and sudden rather than a general ache.

What helps: protecting the teeth while the grinding continues — usually a night splint.

4. A crack, a leaking filling, or decay

This is the one that matters. A tooth that hurts to cold and settles in a second or two is usually one of the first three. A tooth that keeps aching after the cold is gone, or hurts when you bite on it, is a different problem and needs looking at.

Sensitivity that is getting worse week on week, or that wakes you at night, is not something to manage with toothpaste.

When to come in

If it has lasted more than two or three weeks, or if it lingers after the trigger has gone, book a check-up. Finding out which of the four it is takes one appointment.