Why your teeth hurt with cold water — and what to do first

Sharp, short and gone in seconds

A quick zing that disappears the moment the cold water leaves usually means exposed dentine — the layer under enamel, threaded with microscopic tubules that transmit sensation. It gets exposed by gum recession, aggressive horizontal brushing, acidic diets or grinding.

This responds well to a potassium-nitrate or stannous-fluoride toothpaste applied as a paste on the sensitive area at night, plus fixing the cause: a soft brush, gentle circular technique, and a night guard if you grind.

Lingering ache for minutes after the cold

If pain hangs around after the stimulus is removed, or wakes you at night, the pulp is likely inflamed. Toothpaste will not fix this. It usually means deep decay, a leaking old filling or a crack, and it is the stage where a root canal becomes likely if it is ignored.

Pain on biting, not on cold

Sharp pain when you release a bite often indicates a cracked cusp. Cracks are hard to see on X-rays and are usually diagnosed with a bite stick and transillumination. Caught early, a crown protects the tooth; caught late, the crack extends under the gum and the tooth is lost.

Self-checks before your appointment

Note three things and bring them with you — it genuinely shortens the diagnosis.

• Which tooth, or which side, if you cannot localise it
• Whether pain lingers after the trigger is removed
• Whether heat, cold, sweet or biting sets it off

What not to do

Do not place aspirin against the gum, do not switch to a hard brush to 'clean harder', and do not keep chewing on the other side for months. Compensating changes your bite and creates a second problem on top of the first.