Tooth sensitivity has a mechanical explanation. Beneath your enamel sits dentin, which is threaded with microscopic channels running toward the nerve. When enamel thins or gums recede and expose root surface, temperature and sweetness reach those channels, and you feel it sharply.
The useful distinction is between sensitivity that is spread across many teeth and sensitivity that is concentrated in one. Generalised sensitivity often responds to a change in products and technique. Sensitivity in a single tooth is more often a specific problem — and that is the pattern worth having checked.
Possible causes
- Enamel wear from acidic food and drink, or from brushing too hard
- Gum recession exposing root surface, which has no enamel covering it
- Grinding or clenching, which wears biting surfaces and stresses teeth
- A cracked tooth or a failing filling, which typically affects one tooth rather than many
- Recent dental treatment, where short-term sensitivity is expected and usually settles
- Whitening, which commonly causes temporary sensitivity
- Decay reaching the dentin
When to seek prompt care
- Pain that lingers well after the trigger is gone, rather than fading in seconds
- Sensitivity concentrated in one tooth, especially when biting down
- Pain that wakes you at night or does not respond to over-the-counter pain relief
- Swelling of the gum or face near the tooth
- A visible crack, chip, or lost filling
For life-threatening emergencies — trouble breathing or swallowing, severe uncontrolled bleeding — call 911 first.
How a dentist assesses it
A dentist works out which teeth are involved and what is triggering the response — cold, sweet, pressure, or biting — because the pattern points in different directions. An exam checks for wear, recession, cracks, failing restorations, and decay, and X-rays show what is happening below the surface. Sensitivity spread evenly across many teeth suggests one kind of cause; a single sharp tooth suggests another.
Treatment paths this may lead to
Questions patients ask
How long should sensitivity toothpaste take to work?
Formulas that calm the nerve response typically need two to four weeks of consistent twice-daily use before you can judge them. Giving up after a few days is the most common reason people conclude it did not work.
Is sensitivity always a sign of a cavity?
No. Plenty of sensitivity comes from wear or recession rather than decay. But sensitivity in one specific tooth, particularly on biting, is worth having looked at rather than managed with toothpaste.
Can whitening cause lasting sensitivity?
Whitening commonly causes temporary sensitivity that settles after treatment stops. Sensitivity that persists well beyond that is worth mentioning to your dentist.
Does sensitivity mean my enamel is gone for good?
Enamel does not grow back, which is why prevention matters. But sensitivity is often manageable, and identifying what is causing the wear can stop it progressing.
This guide is general dental-health information, not a diagnosis or individualized medical advice. Only an examination can determine what's happening in your mouth and which treatment fits.