Some sensitivity after a filling is common and normally settles within one to two weeks. Pain that lasts longer, is getting worse, lingers after hot or cold, wakes you at night, or makes biting painful needs to be checked.
Placing a filling, especially a deep filling, irritates the pulp (nerve) inside the tooth. Mild sensitivity to cold, sweet foods or biting is common for a short time afterwards. This kind of sensitivity is brief, fades within seconds of the trigger being removed, improves steadily day by day, and has normally settled within one to two weeks.
If the new filling is a fraction too high, the tooth takes more than its share of the bite and becomes sore when you chew. Your dentist can adjust a high filling in a few minutes, and the soreness then settles.
When decay has reached close to the pulp, the pulp may already be inflamed before the filling is placed. If the inflammation is reversible, the pulp settles once the decay is removed. If the inflammation is irreversible, pain lingers after hot or cold, can start without any trigger, and may wake you at night. Irreversible pulpitis does not settle on its own and needs root canal treatment. Read more in my guide to pulpitis.
A tooth that has had a large filling can be weakened, and a crack may already have been present before the filling was placed. A crack typically causes sharp pain on biting, particularly on releasing the bite. Read more in my guide to toothache when biting.
Occasionally the pulp dies some weeks or months after a deep filling. Bacteria can then infect the root canal system and spread to the bone around the root tip. The tooth may feel tender or “high” on biting, and there may be gum swelling or a small gum boil nearby. Treatment is root canal treatment.
Diagnosis combines your history (how the pain has changed since the filling, what triggers the pain and whether the pain wakes you) with a cold test, percussion and bite testing, periapical X-rays, and a CBCT scan where more detail is needed. Examining the tooth under the dental operating microscope helps to find cracks and leaking margins around the filling.
See your dentist if the pain is getting worse rather than better, lingers for more than a few seconds after hot or cold, starts on its own or wakes you at night, makes biting painful after the filling has been adjusted, or has not settled after one to two weeks.
In the meantime, over-the-counter pain relief such as paracetamol or ibuprofen, taken as directed, can help. If you have facial swelling that is spreading, or any difficulty swallowing or breathing, seek urgent medical care straight away.
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