Tooth Pain and Sensitivity: Causes, Relief and When to See a Dentist

Sensitivity versus pain: two different signals

Tooth sensitivity is a brief, sharp reaction to hot, cold, sweet or acidic food that fades within a few seconds of the trigger being removed. It happens when the outer enamel has thinned or the gum has receded, exposing the underlying dentine, which is riddled with microscopic tubules that carry sensation straight to the nerve. This kind of discomfort is common, usually manageable, and does not always mean something is seriously wrong.

Tooth pain is different. It tends to linger after the trigger is gone, can throb on its own, may worsen when lying down or biting, and sometimes wakes a person at night. Lingering pain like this usually points to inflammation or infection inside the tooth rather than simple surface sensitivity, and it is the pattern that should prompt a dental visit rather than home management alone.

Both symptoms are worth taking seriously because they are the mouth's main way of reporting a problem before it becomes visible or urgent. Ignoring either one for weeks or months tends to let a small, easily treated issue turn into a larger one.

Common causes of sensitivity

Gum recession exposes the root surface, which has no protective enamel layer, so hot and cold reach the nerve much more easily than through a healthy crown of enamel. Recession can result from aggressive brushing with a hard-bristled brush, untreated gum disease, or simply the gum thinning gradually with age.

Enamel wear from acidic foods and drinks, teeth grinding, or over-vigorous brushing thins the protective layer over time. A cracked filling, a leaking old restoration, or a tooth that has recently been whitened can also cause temporary sensitivity that usually settles within days.

Sensitivity toothpaste containing potassium nitrate or stannous fluoride, used consistently for a few weeks, blocks the dentine tubules and calms many mild cases. A dentist can also apply a desensitising varnish or a bonded resin directly to an exposed root surface for faster relief when toothpaste alone is not enough.

Common causes of tooth pain

Deep decay that has reached the nerve, a cracked tooth, an old filling that has failed underneath, or an abscess forming at the root tip are the usual reasons for pain that lingers or throbs. Pain on biting specifically often points to a cracked cusp or a high filling rather than decay, while pain that is worse lying down and better sitting up is a classic sign of pressure building from infection.

A tooth that has darkened compared with its neighbours, gum swelling near a single tooth, or a small pimple-like bump on the gum are all signs that the nerve inside a tooth may already be dead or infected, even if pain itself comes and goes. These signs are usually followed up with an X-ray to see the extent of the problem before deciding on treatment.

Where the nerve is infected or irreversibly inflamed, root canal treatment removes the source of pain and preserves the natural tooth, followed by a crown to protect it once the internal structure has been hollowed out and refilled. Where a tooth is too badly broken down to save, extraction is considered, usually with a plan discussed for replacing the gap afterwards.

What happens at the appointment

A dentist examines the tooth, tests its response to cold and to gentle tapping, and usually takes a small X-ray to see below the gum line, where much of the relevant detail is hidden from the naked eye. This combination generally makes it possible to tell within one visit whether the problem is superficial sensitivity, a cavity, a cracked tooth, or an infection needing root canal treatment.

Pain relief is prioritised immediately if you arrive in discomfort, and definitive treatment is then explained clearly, with the reasoning behind the recommended option, before anything irreversible is carried out.

Simple steps while you wait for an appointment

Use a soft-bristled brush and a sensitivity toothpaste, avoid very hot, cold, sweet or acidic foods on the affected side, and take a routine over-the-counter painkiller if needed, following the dosing instructions on the packet. Rinsing gently with warm salt water can settle mild gum irritation around a tooth.

Avoid chewing directly on a painful tooth and do not apply heat to the face if there is any swelling, since this can make an underlying infection worse rather than better.