1. Apply direct pressure to the gum with a clean washcloth or rolled-up piece of gauze. If she's old enough to understand, have her bite down on it gently.
2. Find the missing tooth and put it in a small plastic bag. Unlike permanent ones, baby teeth can't be reimplanted, but your dentist will still want to see it.
3. Get to the dentist right away. He'll inspect the tooth and x-ray your child's mouth for missing fragments, which can cause adult teeth to come in crooked. If a baby molar gets knocked out, the dentist may put in spacers to guide in future teeth.