The question is what uncovered your dentin.

Under your enamel sits dentin, and dentin is not solid: it is threaded with microscopic tubules running straight to the nerve. Whenever dentin loses its cover, cold, heat, sweetness and even a breath of winter air get a direct line inward, and that jolt is sensitivity. Everything on this page is a variation on one question: what uncovered your dentin? Gum recession exposes root surfaces that never had enamel; brushing too hard with a stiff brush sands enamel and gums alike; acid, from diet or reflux, dissolves enamel chemically; grinding wears it mechanically and can flex tiny notches into the necks of teeth; whitening opens tubules temporarily; and sometimes the answer is a cavity or crack borrowing sensitivity's costume.

That last possibility is why sensitivity earns an exam rather than a lifetime toothpaste subscription: generalized, symmetric sensitivity is usually the benign story, but one tooth newly sensitive, sensitivity that lingers after the trigger, or a jolt on biting each point at a specific problem, decay, a crack, a failing filling, wearing sensitivity as a disguise. The pattern sorts it, and the table below is the sorting.

For the common, benign version, the boring answers genuinely work, with one catch: patience. Desensitizing toothpaste plugs or calms the tubules but needs two to four weeks of twice-daily use before judging it, and most people quit at day five; a soft brush and lighter grip stop the sanding; a straw rearranges how cold drinks meet your teeth; and cutting the all-day acid habits, sipped soda, constant citrus, sports drinks, removes the chemistry. Where home care plateaus, in-office options escalate sensibly: professional fluoride or desensitizing varnish on the worst surfaces, protective composite over exposed necks, and a night guard where grinding is the engine.

Grinders get a targeted note as well: clenching and grinding flex teeth at their necks, which is how those small notches appear at the gumline and why sensitivity there so often travels with morning jaw tightness. Where that pairing shows, the night guard is treating the cause and everything else is treating the symptom.

One diet habit deserves its own line because it quietly undoes everything: brushing immediately after acidic food or drink scrubs enamel while acid has it softened, so rinse with water after the orange juice or the wine and give brushing thirty minutes, a free change that protects more enamel than most products.

The escalation rule is the page's real advice: sensitivity that survives a month of honest home care, arrives on one tooth, or starts lingering has graduated from nuisance to symptom, and symptoms get exams. At your checkup the pattern, your gumline and your wear facets tell the story quickly, the cause gets named with the evidence on screen, and the fix is matched to the cause rather than sold from a shelf.