Root canal treatment, explained

In the middle of every tooth is the pulp: nerve and blood vessels, sealed in a chamber that runs down into the roots. It can become irreversibly inflamed or infected when:

• Decay reaches it
• A tooth is cracked or heavily worn
• An injury damages the blood supply, sometimes years earlier
• A very deep filling eventually proves too much for it

Once the pulp dies, bacteria occupy a space the body’s immune system cannot reach. That is the whole problem, and it is why antibiotics alone never solve it — there is no blood supply left to carry them in. Antibiotics do not help the inflamed-but-still-living pulp either: that pain is not an infection the body is losing, and the only thing that settles it is treating the tooth.

Classically: pain that lingers after something hot or cold rather than stopping in a second or two, pain that wakes you at night, or a tooth that becomes exquisitely tender to bite on. Sometimes a gumboil appears.

Sometimes there is no pain at all and it is found on an X-ray.

Numbing, as for a filling.

Isolation. A sheet of latex or latex-free rubber is clipped over the tooth. This looks odd and is genuinely helpful: it keeps saliva out of the canals and stops anything being swallowed. You can still swallow normally.

Access. A small opening is made through the top of the tooth into the pulp chamber.

Cleaning and shaping. The canals are cleaned with fine instruments and disinfecting solutions, and measured — often electronically — so the work stops exactly at the root tip.

Filling. The canals are sealed with a rubber-like material called gutta-percha, which keeps bacteria out of the space.

Restoring. The access hole is filled. On back teeth, a crown usually follows, because a root-treated molar has lost structure and is prone to splitting under chewing loads.

The tooth is commonly tender to bite on for a few days — the ligament around it has been irritated. Ordinary painkillers handle it.

A root-treated tooth has no nerve, so it will not feel hot and cold again. It is otherwise a working tooth.

Yes, usually. Success rates for a well-executed root canal are high, and a treated tooth can last decades — in many cases for life. Failures do happen, most often where a canal was difficult to find or the tooth was already heavily broken down, and a re-treatment or referral to a specialist is sometimes the answer.

The pain people associate with root canal treatment is the reason for it, not the result of it.