If your child gets a permanent tooth knocked out, find it (if possible) and put it in a jar of milk. Hold clean gauze at the spot of the knocked out tooth.
Take your child to your dentist or a hospital Emergency Department as soon as you can. The dentist may be able to replant the tooth, but only if you get there as soon as possible.
If your child gets hit in the mouth and there is tooth, gum and lip damage, take them to a hospital Emergency Department right away.