Whether it's a baby or permanent tooth, shine a flashlight on the exposed edge of the broken tooth; if you see a red spot, the tooth is bleeding inside, exposing the nerve. This is an emergency, so you’ll need to see your dentist immediately. If you can find the piece of tooth, bring it with you -- your dentist may be able to bond it in place. If no red spot is visible, it’s fine to see the dentist the next day but call to tell him or her what’s going on. Your child probably won’t be in pain, though the tooth may be sensitive to hot and cold.