Knocked out tooth is one which is completely displaced from its socket, in medical terms this is referred to as ‘Tooth avulsion’. Whether you are looking after children in a school or playground, playing contact sports yourself or are involved in some kind of accident, one of the most common problems that you can encounter is the tooth getting knocked out of its socket.
Avulsion or knocking out of permanent teeth is the most serious of all dental injuries. According to research published in 2007 by Flores MT et al, avulsion is reported to be seen in 3% to 16% of all dental injuries.  It occurs most frequently between the ages of 7 to 14 years, usually affecting the maxillary central incisors (upper front teeth).
An avulsed permanent tooth is one of the few real emergency situations in dentistry. And once such an accident occurs the first steps taken and time period become vital in deciding whether the natural tooth will be saved or not. Therefore it is imperative that public awareness is created about first aid care for a knocked out tooth. Healthcare professionals, parents and teachers should receive information on how to proceed following these severe unexpected injuries.
FACTORS THAT MATTER
Before we talk about the first aid steps following a tooth getting removed from its socket, it is important to know the factors that will determine the success of management that you provide. Our primary goal here is to replace the knocked out tooth back in its place and also preserve the supporting tooth structure. Critical factors that we need to keep in mind are the amount of time the tooth spends out of its socket, the storage medium we use while transporting the tooth to dental office and the general health of the patient. 
Another very important factor to be kept in mind is the maturity of the tooth root and whether the tooth knocked out is a permanent tooth or deciduous tooth (milk tooth). Always remember that you should NEVER try to reinsert a milk tooth back in its place. Because by doing so there is a chance that u may damage the permanent tooth that is growing underneath and be ready to come out. In such a situation, contact your dentist and take the child to see him immediately.
EMERGENCY RESPONSE TO TOOTH AVULSION
Now that we have we have talked about the importance of initial management and factors involved in saving a knocked out tooth. Let us go through the steps you will follow when you face such a situation at your home, school or on the street.
KEEP CALM: The thought of tooth getting knocked out of a person’s mouth can be unsettling. Add to that the bleeding involved and painful cries of the affected person and it becomes a perfect recipe for a stream of bad decision. Therefore the most important thing is to keep calm and try to calm down the affected person. Make him sit down and relax while you assess the severity of trauma and rule out any other associated problems like black outs and fainting.
It is important to control the bleeding, but do not apply pressure on the affected area as we do not want to close the space where the tooth came out of. Instruct the affected person not to spit or press his tongue over the empty space. You may slowly rinse the mouth with warm water.
HANDLING THE TOOTH: Tooth Handling is very important as most of the mistakes are made during this time. Gently hold the tooth from the crown (the upper white part). Do not touch root of the tooth as it will damage to the root surface and its supporting structure. If you observe any dust or foreign matter on the tooth surface you can briefly (for 10 seconds) rinse it in a bowl of lukewarm water or normal saline. Do not scrape or scrub the tooth in an attempt remove dirt from the tooth’s surface.
PLAN A: REPLACING THE TOOTH: The ideal option is to replant the tooth in its place within a few minutes. Try to encourage the patient to replant the tooth in its position. If the patient agrees, align the tooth anatomically above the correct socket (make sure you are placing the tooth in its correct place in case of multiple teeth getting knocked out).
Replace the tooth in its space slowly by pressing the crown lightly with your thumb until it is at level with other teeth. Once it is back in its place have the person bite down on a wad of cloth or gauze piece to keep the loose teeth in place.
After successfully replacing tooth in its space, you should contact the dentist right away to set up and emergency appointment so that he can carry out follow-up treatment. Use sterile gauze to control bleeding and apply cool compress to help the swelling subside. Also give and over the counter pain medication like ibuprofen or acetaminophen to relieve the pain.
PLAN B: STORE THE TOOTH: There is no need to panic if you do not succeed in replacing the tooth back in its position. Contact emergency service or find your nearest dentist. During the time you get professional help it is very important to store the tooth properly.
Studies have shown that the storage medium used before replacing the tooth has a great effect on root resorption and pulpal healing. A dry time (leaving tooth out without storing in a suitable medium) of more than 30 to 60 minutes will result in irreversible damage to the periodontal ligaments (supporting structure of tooth). 
If the tooth is not going to be replanted within five minutes, it should be placed in a suitable storage media. There are a variety of options available that can be used to safely store the tooth before reaching dentist;
MILK PACKED IN ICE: In addition to having a low cost and high availability, as it is mostly everywhere. Milk has several favorable characteristics as storage medium for avulsed teeth. Place the tooth in fresh milk packed in ice to prevent further drying. This maintains the ability of cells to reproduce twice as long as milk at room temperature.
HANK’S BALANCED SALT SOLUTION: HBSS is an excellent storage medium for long term storage of a knocked out tooth. This balanced isotonic salt solution has been especially developed for cell maintenance and thus, theoretically, it allows a better conservation of tissues for long time periods.  A limitation with this medium is that it is not readily available everywhere.
EGG WHITE: The major protein in egg white is also considered a good choice as a storage media for teeth undergoing delayed replantation due to its high content of proteins, vitamins and water, absence of microbial contamination and easy access. Khademi et al. compared milk and egg white as solutions for storing avulsed teeth, and found that teeth stored in egg white for 6 to 10 h had more suitable results than those stored in milk for the same amount of time.^
SALINE: Saline has physiological osmolality and pH so it may be employed as a storage medium for short periods of time. Studies have found that saline had a worse behavior as a storage medium when compared with HBSS and milk. As it does not contain essential ions and glucose therefore saline is not an adequate medium, but it can still be used as an interim storage medium for up to 4 hours.
PATIENT’S OWN SALIVA: Although this might not be a pleasant for the person after a traumatic injury. But incase none of the above mentioned storage media are available; a tooth may be placed back in the patient’s mouth for the saliva to act as the storage media. While doing this the risk of swallowing the tooth should be taken into consideration especially in children.
AVOID TAP WATER: It is a common mistake to use tap water to store the knocked out tooth. Tap water has inadequate characteristics to be used as storage medium for avulsed teeth because it has bacterial contamination and low osmolality. Dental Practice Board guidelines suggest that tap water should not be used as a medium as it ruptures PDL cells through osmosis therefore permanently damaging the tooth surface.
AT THE DENTAL CLINIC
Once you have reached the dentist’s office. Give him a brief account of all the events from the time of tooth getting knocked out; If the tooth has been placed back in the socket already the dentist examine the tooth and its socket and order appropriate radiographs. If the tooth is kept in a storage medium the dentist will anesthetize the tooth socket and replace the tooth. After that a general examination and appropriate radiographs will follow.
SPLINTING: In both the situations the dentist will have to splint the avulsed tooth with its adjacent teeth in order to hold it in position for a period of at least two weeks (or four weeks if the dry time was more than 60 minutes).
SOFT DIET AND POST OP CARE: Patient will be instructed to use Soft diet for two weeks and avoid chewing from the area of avulsed tooth. Avoid contact sports and Brush teeth with a soft tooth brush after each meal. Patient should use chlorhexidine 0.1% mouth rinse twice daily for one week. The dentist will also refer the patient to medical personnel for evaluation of need for tetanus toxoid vaccine.