Pain when biting tells us that something is wrong with the tooth itself, the tissues around the root, or the way the teeth meet. The cause can be minor, such as a filling that sits slightly high, or a sign that the tooth needs treatment, such as a crack or an infection at the root tip. Finding the exact cause matters, because each cause is treated differently.
A crack is one of the most common causes of sharp pain on biting, especially pain on chewing something hard or on releasing the bite. Cracks are often too fine to see on an X-ray. Pain can come and go, and is often hard to pin to one tooth. Left untreated, a crack can let bacteria reach the pulp (nerve) or can spread further down the root. Read more in my cracked teeth guide.
When the pulp has died, bacteria in the root canal system can spread to the bone around the root tip, a condition called apical periodontitis. The tooth then feels tender, bruised or “high” when you bite, and may be sore to touch. Sometimes there is gum swelling or a small gum boil nearby. Infection at the root tip can affect a tooth that has never had treatment, or a root-treated tooth where infection has returned. Treatment is root canal treatment, or re-treatment of a tooth that has been treated before.
Pulpitis usually causes pain with hot or cold, but as inflammation spreads towards the root tip a tooth can also become tender on biting. Read more in my guide to pulpitis.
If a tooth has just been filled or crowned, the new restoration may sit slightly high, so the tooth takes more than its share of the bite. Your dentist can adjust a high restoration in a few minutes. Pain on biting that continues after the bite has been adjusted needs further investigation.
A gum (periodontal) abscess or trapped food can make a tooth tender. Clenching or grinding puts heavy forces on the teeth and can make several teeth ache, often worse in the morning. Upper back teeth sit close to the maxillary sinus, so sinusitis can make several upper teeth ache, often worse when bending forward.
Diagnosis combines your history (when the pain started and what triggers the pain) with a cold test, percussion and bite testing on individual cusps, periapical X-rays, and a CBCT scan where more detail is needed. Examining the tooth under the dental operating microscope helps to find cracks that are invisible on X-rays.
Chew on the other side and avoid very hard foods. Over-the-counter pain relief such as paracetamol or ibuprofen, taken as directed, can help in the short term. Pain on biting rarely settles on its own, so see your dentist, who can refer you if needed.
If you have facial swelling that is spreading, or any difficulty swallowing or breathing, seek urgent medical care straight away.
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