You need to take him to your dentist tmrw! The tooth will not regenerate or continue to grow in. The tooth could have nerve damage and may require a root canal, which may not be apparent immediately. Sometimes the nerve dies as a result of trauma and sometimes it does not. But you do need to have it xrayed and make sure there isn't any damage to the bone around the tooth. Unfortunately, boys are notorious for breaking/knocking out a front tooth. Happens quite frequently it seems. You don't need to panic, but just make sure he is seen by a dentist and keep an eye on the tooth for swelling/abscess in the gum areas in the next few weeks. Poor guy!