How the infection develops

Bacteria enter the pulp through deep decay, a leaking restoration, a crack or an injury. The pulp dies and the hollow canal system becomes a reservoir of bacteria. Their toxins seep out through the root tip, the body dissolves a small pocket of bone in response and an abscess forms. It may throb and swell, or smoulder for months without a sign.

Warning signs

a tooth that aches or is tender to bite on;
swelling of the gum beside the tooth, or of the cheek or lip;
a small spot on the gum that discharges and returns;
a bad taste, or a tooth that has darkened;
no symptoms at all — many infections are discovered on a routine X-ray.

Pain that stops abruptly is not a cure; it usually means the nerve has died and the infection has moved into the bone.

Why antibiotics are not enough

Antibiotics travel in the blood, and a dead tooth has none. A short course may be appropriate while a spreading swelling is brought under control, but it cannot clear bacteria inside the canals, and the infection returns when the course ends. Lasting treatment means cleaning and sealing the canal system: root canal treatment for a tooth not previously treated, or retreatment where an earlier root filling has failed.

How treatment resolves it

With the canals cleaned, disinfected and sealed, the bacteria have nowhere left to live. The body then heals the bone around the root over the following months, confirmed on a review X-ray. Where infection persists despite good treatment, microsurgery removes the root tip and infected tissue directly.

When it is urgent

A swelling spreading towards the eye or under the jaw, difficulty swallowing or breathing, a high temperature or feeling unwell indicate the infection is spreading. Contact NHS 111 or go to A&E if you cannot be seen by a dentist at once. For severe toothache without those signs, see emergency endodontic care.

Related endodontic care

Root canal treatment

Root canal treatment ends the pain of an inflamed or dead nerve, clears the infection and keeps the tooth. In Rugby it is carried out under magnification, with the tooth fully numbed and isolated, and most teeth are completed in a single visit.

Root canal retreatment

When a root-treated tooth becomes painful or infected again, retreatment can usually save it. The earlier root filling is removed, the canal system is cleaned thoroughly — including any canals missed first time — and the tooth is sealed and restored once more.

Microscope-assisted endodontics

Root canals can be finer than a hair and hide behind calcified dentine. Working under an operating microscope gives bright, magnified sight of the inside of the tooth — the difference between guessing and seeing. It is how every root canal treatment and retreatment is carried out here.

Root canal infection in Rugby