First, assess the situation
A crown that has come off is different from a fracture in the underlying tooth. Keep the crown if you can retrieve it and contact a dental office for assessment. Avoid chewing on the affected side, particularly if the tooth is sensitive or has a sharp edge.
Do not improvise permanent repairs
Do not use household adhesives or attempt to grind or reshape the tooth. A dentist needs to determine whether the crown still fits, whether decay or fracture is present, and whether recementation is possible. The old crown may not be reusable.
If the exposed tooth is sensitive
Avoid very hot, cold or hard foods if they provoke pain, and keep the area clean with gentle brushing. A pharmacist may advise on over-the-counter pain relief appropriate to your circumstances. Pain relief does not resolve a broken restoration or an underlying infection.
When to seek urgent care
Arrange prompt dental assessment for significant pain, a loose or broken restoration, or a tooth injury. Increasing swelling, fever with concerning symptoms, or difficulty opening the mouth needs urgent attention. Severe facial swelling affecting breathing or swallowing requires emergency medical services.
What the dentist may recommend
Depending on the examination, options can include recementing the existing crown, fabricating a replacement, repairing a damaged core, treating the tooth internally or discussing extraction if it cannot be restored. The underlying diagnosis—not the crown alone—drives the decision.