How long does pain last after a root canal, and when is it not normal?

Why is there pain after a root canal?

In root canal treatment the inflamed or dead nerve tissue inside the tooth is removed and the canals are shaped and filled. Although the tooth itself no longer transmits pain, the bone and ligament around it (the periodontium) are affected: cleaning the canals causes slight irritation at the root tip, and existing inflammation takes time to heal. Tenderness on pressing, chewing or tapping the teeth together for a few days after treatment is therefore expected.

How many days does it last?

• First 24–48 hours: The most noticeable period. Once the numbness wears off, a dull ache and biting tenderness begin.
• Days 3–5: Clear improvement; most patients no longer need painkillers.
• 1–2 weeks: Biting tenderness disappears completely. If there was a large area of inflammation at the root tip (an apical lesion), mild tenderness can last a few weeks; bone filling in on the X-ray takes months.

Teeth that had severe pain or an abscess before treatment take a little longer to settle; your dentist will tell you during treatment.

What reduces the pain?

1. Don't eat until the numbness wears off; you could bite your lip or cheek.
2. Don't chew on that side for the first days. Avoid hard and sticky foods until the temporary filling has fully set.
3. Take the painkiller your dentist recommends as directed, at regular intervals before the pain starts; on the first day this works better than waiting for pain. If you take blood thinners or have stomach problems, leave the choice of drug to your dentist.
4. Keep your pillow a little higher; it reduces the throbbing that increases on lying down.
5. Keep brushing the tooth; clean the gum margin gently and floss as normal.

When is it not normal?

Call the clinic without waiting if any of the following occurs:

• Swelling of the face or gum, fever, malaise
• Throbbing that increases rather than eases day by day, especially waking you at night
• Marked pain lasting more than a week and not relieved by painkillers
• The temporary filling falling out, or a feeling that the tooth has cracked
• A "high" contact on biting — the bite is adjusted in a few minutes and pain eases at once

Most of these are resolved by re-irrigating the canal, adjusting the bite or a short course of medication; in very few cases the root canal is redone or apical surgery is needed.

Why should the tooth be crowned after treatment?

Root-treated teeth are more brittle because they have lost their nerve and moisture; back teeth in particular can crack under chewing forces. A permanent filling and, if needed, a crown or onlay within the time your dentist advises is therefore the single most important step in the tooth's survival. Waiting a long time with a temporary filling leads to leakage and failure of the treatment.

Frequently asked

Does root canal treatment hurt? It is done under local anaesthesia; inflamed teeth can be harder to numb, in which case additional anaesthetic is given.

Which painkiller? The one your dentist recommends; simple painkillers are enough for most patients. Antibiotics are needed only if there are signs of spreading infection; "an antibiotic with every root canal" is not correct practice.

The tooth is still sensitive to cold — is that normal? A root-treated tooth does not feel cold; cold sensitivity may be coming from a neighbouring tooth and is told apart at the check-up.

For more, see Root canal treatment.