Dental injuries can be a traumatic experience, if you are unfortunate enough to knock out one of your teeth, the chances are god that the tooth can be saved as long as you have not swallowed it and the tooth is otherwise undamaged.
There are established steps that you can take that will maximize the chances of your knocked out tooth surviving.
As long as you act quickly, then it may be possible to successfully replant your tooth.

• You will definitely need to see your dentist so the first thing you should do is to ask for an emergency appointment as soon as possible.
  If you explain that the appointment is needed because of a knocked out tooth then the dentist will understand the urgency of the situation and should be able to fit you in quickly.
  
• Do not touch the root of your tooth.
  This is because the root is quite delicate and if it is damaged then your tooth will not be able to be saved.
  It is better if you only handle the tooth by the crown.
  This is the white part of the tooth that is normally visible above your gum.
  
• Do not attempt to brush the tooth or to scrape it.
  Again you may inadvertently damage the tooth.
  If you are worried that the tooth may be dirty then you should rinse it.
  It is best to use either milk for this or a mild salt water solution.
  Do not attempt to rinse the tooth by using alcohol as this could kill the root.
  
• The tooth needs to be put back in place in your gum as soon as possible to increases the chances of saving it.
  Your gum will already be sore and may be bleeding so it is best to reinsert the tooth as slowly and gently as possible.
  You may find it easier to use a mirror so that you can see what you are doing more clearly and ensure that the tooth is correctly positioned.
  Once the tooth is fully reinserted into your gum then you will need to bite down on something in order to hold the tooth in position.
  A folded clean handkerchief is probably the best choice although you could also use a wet tea bag.
  
• If you cannot manage to reinsert the tooth into the socket yourself then you have two options.
  If you are going straight to the dentist then you could keep the tooth in your mouth between your gum and your cheek as this will keep it moist.
  Alternatively you could store the tooth in a small pot.
  If you do this then it is vital that you cover the tooth either with milk or some of your saliva.
  

These steps only apply to adult teeth.
If a child knocks out a milk tooth then it should be left as the adult tooth will soon grow to replace it.
When you see your dentist, he will check how the tooth has been reinserted into the socket or attempt to reinsert it for you.
You will then have to wear a splint on the tooth to hold it in the correct place.
This may need to be worn for several weeks in order to ensure that the tooth has had the chance to be successfully embedded back in your gum.
If it is not possible to save your tooth then your dentist will discuss several options with you to fill the gap.
These include dentures, bridges where a false tooth to fill the gap would be attached by cement to the teeth either side, or an implant where a replacement crown is permanently fitted by inserting a titanium implant into your jawbone.