What a crown does after root canal treatment, and why it should not wait

Patients are sometimes surprised that the root canal is not the end of the story. It treats the disease inside the tooth, but the tooth itself has been changed by what it went through, and protecting it is the second half of a successful outcome.

What root canal treatment does to a tooth

A tooth that has needed root canal treatment has usually already lost structure to decay, a large filling or a crack. Treatment removes a little more to reach the canals, and it removes the pulp — which means the tooth no longer has a blood supply and becomes drier and more brittle over time. A molar in that state, left with only a filling, is vulnerable to cracking under the forces of chewing.

Why a crack matters so much

A crack that runs down into the root cannot be repaired. It is the one failure that neither retreatment nor surgery can fix, and it means extraction. Most such cracks occur in root-treated teeth that were never properly protected, which is why the restoration is not an optional extra but part of the treatment.

Crown, onlay or filling?

A crown covers the whole tooth and holds it together from all sides. An onlay covers the biting surface and the cusps, binding them so that they cannot flex apart, while preserving more of the natural tooth. A filling alone is appropriate only where enough sound tooth remains — typically a front tooth with a small access cavity. The recommendation for your tooth is included in the report your dentist receives after treatment.

How soon?

Ideally within a few weeks of the root filling. The temporary filling placed at the end of treatment is designed to last for a short period, not indefinitely; it wears, it can leak, and an unprotected tooth can crack at any time. If the final restoration is going to be delayed, say so, and a stronger temporary restoration can be placed in the meantime.

Who does what

The endodontist treats the inside of the tooth and seals the canals. Your own dentist, who knows your mouth and your other teeth, fits the crown or onlay and continues your routine care. The report sent after treatment includes the X-rays and the restorative recommendation, so that the hand-over is seamless.

Looking after a crowned, root-treated tooth

Brush and floss as you would any other tooth, paying attention to the edge where the crown meets the tooth, because new decay there is one of the ways a root-treated tooth can fail years later. Keep up your routine check-ups; a periodic X-ray lets your dentist confirm that the bone around the root remains healthy. Treated this way, a root-treated tooth is a long-term member of your mouth — see root canal treatment for the full picture.