A lost crown is not always dramatic, but it can matter
When a crown comes off, the tooth underneath may be exposed, sensitive, or more likely to break further if you keep chewing on it. Some lost crowns are mainly inconvenient. Others are much more urgent because the tooth underneath is weak or painful.
The safest next step is usually to call and describe what happened instead of assuming it can wait indefinitely.
What to do while you wait
Keep the crown if you still have it and bring it with you. Avoid chewing on that side, especially if the tooth feels sharp, fragile, or temperature-sensitive. The longer the tooth stays exposed, the more likely sensitivity or additional damage may become.
When to call right away
Call promptly if the tooth hurts, if the crown came off after a fracture, or if the tooth beneath it feels loose, sharp, or unstable. Clear guidance early often makes the repair simpler.