Your child just fell riding his bicycle. There is lots of blood. His mouth is a mess. Who do you call? What do you do? Children will find a way to injure themselves despite our best preventive measures as parents. Some orofacial injuries are serious and some are nothing to worry about. How do you tell? Well, here are some guidelines.
If there is lots of blood, don't panic. Any injury to the mouth bleeds a lot. Check out the situation; hold a cloth (if you can) with pressure to slow the bleeding. Most bleeding stops within 10 -15 minutes whether you do anything or not. Once your heart stops racing so much and the child is not in such a state, look and see what the problem is. First look and see if there are facial cuts or lacerations, fear of a broken jaw, possible head trauma causing loss of consciousness (concussion), multiple knocked out and displaced teeth (an oral surgeon may need to see you at the hospital), or if you just are not too sure, then you need to go to the ER. They can stitch up any facial lacerations and take major X-Rays to check all that other stuff.
Now, if you don't have those bad things, you still might have a scary mess to deal with. If you go to the ER, you are likely to sit there for two hours and then they will call your dentist anyway. You can call your dentist first and he may be able to save you the trip to the ER.
*If a young child has hit his mouth, there is lots of blood especially on his upper teeth lip area, look and see if it might just be a torn maxillary frenum. That's the little piece of tissue that connects the upper lip to the gum between the two front teeth. If it was tight and gets hit and stretched too much it will tear. It bleeds a lot at first, but will likely be fine after 20 minutes or so. Usually no stitches are necessary. In fact there may be no treatment needed at all. This is a very common injury in preschoolers.
If there is a broken tooth, the ER is not likely to be able to do much. If a tooth is knocked out, and if it is a permanent tooth, you need to get the tooth back in soon as possible, your dentist can help. The ER can put a knocked out tooth back in too, but you still may need a dentist to splint the tooth, so you may want to call the dentist first. If the knocked out tooth is a baby tooth, just leave it out and put it under their pillow. A baby tooth can be intruded (pushed up into the gums) where is is difficult to see. Sometimes it can re-erupt on it's own, but still may need to be removed or need other longer term treatments. If your child is in braces and a wire breaks, etc., call your pediatric dentist or orthodontist.
Here is a useful link for quick reference: APDA Dental Emergencies Quick Reference
More here: Fractured Teeth, Knocked out Teeth, and other Pediatric Dental Accidents
More here: My Child's Tooth is Turning Dark!