What's the first aid for a broken or knocked-out tooth?

If a tooth has been knocked out completely, the most important thing is to reach a dental clinic within 30 minutes. 1) Hold the tooth by the crown, never by the root, 2) if it is dirty, rinse it gently under running water for about 10 seconds only, and 3) place it in milk or saline, or hold it inside your cheek, and come in immediately. If the tooth is only broken, bring the fragment as well, as it can sometimes be bonded back on. However, do not wrap it in tissue and bring it dry - the root cells are damaged that way and replanting becomes difficult.