There are several things that you as mom or dad have to know how to do or what to expect. Sometimes when these happens, the upper or lower lip gets so injured that bleeds a lot so the first thing to do is stop the bleeding by applying firm pressure to the area. When you achieve a proper blood clog the second thing to do is to review all the anatomical parts of the mouth. See if teeth are broken, moved away, bleeding around it. These is very important because these information it's very crucial for your dentist.

If the tooth got out of the oral cavity, look for the teeth, take it by the coronal part (crown is what we see of the tooth in the mouth), wash it with plain water do not scrub it because these will take out the periodontal ligament, next you can re introduce the teeth to it's original place or take it do the dentist office but in a little bit of milk to maintain the humidity.

If the teeth didn't got out of the mouth but it is broken, or have some mobility and blood around it, it's probably possible that the teeth will need a root canal treatment, the dentist will have to (in the future) make a crown to repair the damage.