What causes tooth sensitivity?
Beneath the enamel of every tooth is a softer layer called dentine, and dentine is not solid. It is threaded with microscopic tubules running inward toward the nerve. When enamel is worn away or the gum recedes to expose root surface, those tubules are opened to the outside world — and cold, heat, sweetness, and pressure can travel down them to the nerve.
That is why sensitivity feels so disproportionate to its cause. Nothing is wrong with the nerve; it is simply being reached by stimuli that healthy enamel would have insulated it from.
The common routes to exposed dentine:
- Enamel wear from acidic food and drink, or from grinding
- Gum recession exposing root surfaces, which have no enamel at all
- Cavities breaching the enamel
- Cracked or fractured teeth
- Recent dental treatment, which usually settles on its own
- Aggressive brushing, which wears both enamel and gum
Types of tooth sensitivity, and what each one suggests
The character of the pain is genuinely diagnostic — more so than its intensity. This is the first thing a dentist will ask you about, so it is worth paying attention to before you call.
| What you feel | What it often suggests | | --- | --- | | A sharp twinge to cold that fades within seconds | Exposed dentine from enamel wear or recession. Usually manageable. | | Pain that lingers after the trigger is removed | The pulp inside the tooth may be inflamed. Needs assessment. | | Sharp pain on biting | A cracked tooth, a loose or high filling, or early infection. | | Spontaneous or throbbing pain, especially at night | Inflammation or infection inside the tooth. Prompt assessment. | | Sensitivity to heat specifically | Often a sign of more advanced pulp involvement. | | Generalised sensitivity across many teeth | Enamel erosion, grinding, or over-vigorous brushing rather than one bad tooth. |
The distinction that matters most is brief versus lingering. A twinge that stops the moment you swallow the cold drink is a very different signal from an ache that carries on for a minute afterwards.
Why does my tooth hurt with cold, heat, or sweets?
Cold is the most common trigger, and on its own the least worrying. Cold causes fluid inside the dentinal tubules to contract rapidly, which the nerve registers as a sharp, short pain.
Sweetness works by a similar mechanism — sugar draws fluid osmotically through the tubules. Sensitivity to sweet things often points to a cavity specifically.
Heat deserves more attention than the other two. Sensitivity to hot food and drink, particularly when it lingers, more often indicates that the pulp is inflamed or dying. Heat sensitivity that has appeared recently is worth a call rather than a wait.
Pressure or biting points to something structural — a crack, a failing filling, or a filling that sits a fraction too high.
How to relieve tooth sensitivity at home
Home measures manage symptoms. They do not treat a cavity, a crack, or an infection, and none of them are a reason to postpone an assessment if the pain is significant.
Use a desensitizing toothpaste properly
Twice daily, and give it two to four weeks. For a specific sensitive spot, smear a little on it before bed and do not rinse afterwards — leaving it in contact overnight is far more effective than brushing and rinsing away.
Switch to a soft brush and ease off the pressure
Hard brushing wears enamel and pushes gums back, worsening the exact problem you are trying to fix. An electric brush with a pressure sensor helps if you tend to scrub.
Take the acid out of the equation
Citrus, fizzy drinks, wine, and vinegar soften enamel temporarily. Do not brush for about half an hour after anything acidic — brushing softened enamel removes it. Rinse with water instead.
Over-the-counter pain relief, taken as directed
Ibuprofen is generally effective for dental pain. Acetaminophen is the alternative if NSAIDs are unsuitable for you. Follow the package instructions.
Avoid your triggers for now
Very hot, very cold, and very sweet, until you have been seen.
When tooth pain means you should be seen today
Call the clinic as soon as possible if you have:
- Swelling of the face, jaw, or neck
- Fever alongside dental pain
- Difficulty opening your mouth fully
- Pain severe enough to prevent sleep
- Pain that has been building over several days rather than settling
For urgent but non-life-threatening problems we aim to see you the same day — see emergency dentist in Richmond Hill, or what counts as a dental emergency if you are unsure how to judge it.
What we do at a visit for tooth pain
The goal of the first appointment is to find out which tooth and why, because the treatment follows entirely from the diagnosis.
- History. When it started, what triggers it, how long it lasts, whether it wakes you. This narrows things considerably before anything is examined.
- Examination. Visual inspection for decay, cracks, failed restorations, and gum condition.
- Testing. Cold or electric pulp testing to establish whether the nerve is healthy, inflamed, or dying, and tapping to check for infection at the root tip.
- X-rays. These show decay between teeth, infection at the root, and bone levels — things no visual examination can reveal.
Treatment depends on what is found: a filling for decay, adjustment or replacement of a high or failing restoration, a crown for a cracked tooth, root canal therapy where the pulp is irreversibly inflamed or infected, or gum treatment where recession and inflammation are the cause. Where sensitivity is simply exposed dentine, fluoride varnish or a bonded desensitizer applied in the chair often helps quickly.
How to prevent sensitivity coming back
- Brush twice daily with a soft brush and gentle pressure; use a desensitizing toothpaste if you are prone to it.
- Wait 30 minutes after acidic food or drink before brushing.
- If you grind or clench — particularly if you wake with jaw ache or headaches — a night guard protects enamel from wear that cannot be undone.
- Keep gums healthy. Recession exposes root surface permanently, so bleeding gums are worth addressing early for this reason as well.
- Keep regular check-ups. Most cavities are found before they hurt, and that is the cheapest and simplest point to deal with them.
Booking a check-up through general dentistry is the straightforward route if pain is mild but persistent and you are not sure whether it counts as urgent.