A permanent tooth that has been fully knocked out (dental avulsion) is a true medical emergency. Saving the tooth often depends on the immediate actions taken by the person on the scene. If immediate replantation into the socket is not possible, the universal recommendation is to place the tooth in a container of milk. This standard guidance is followed because milk provides an environment uniquely suited to preserving the tooth’s viability until a dentist can take over.
The Critical Role of Root Cell Viability
The success of replanting an avulsed tooth depends entirely on the survival of the cells covering the root surface. This delicate tissue is called the periodontal ligament (PDL), which forms the attachment between the tooth root and the jawbone. When the tooth is knocked out, these living PDL cells are severed from their blood supply and their environment.
These cells are necessary for the tooth to reattach properly to the bone once it is put back in place. If the PDL cells die, the body’s natural healing process can lead to the root being absorbed and replaced by bone, a process called replacement resorption, which ultimately causes the tooth to be lost.
The viability of these cells is extremely time-sensitive, as they begin to die rapidly when exposed to air and dry conditions. A tooth left to dry for as little as 15 minutes can suffer significant cell damage, and after an hour, the prognosis for successful replantation drops sharply. Therefore, the immediate goal of any storage medium is to keep the PDL cells alive and healthy. Storing the tooth in a moist, protective solution slows down the rate of cell death, maintaining necessary biological conditions until professional treatment can be administered.
How Milk Provides the Ideal Storage Environment
Milk is the preferred storage medium because its chemical makeup closely mimics the physiological conditions required to keep the PDL cells viable. The primary reason for milk’s effectiveness is its osmolarity, which refers to the concentration of dissolved particles in the solution. Milk is near-isotonic, meaning its salt and sugar concentration is similar to the cells of the body.
This near-isotonic state prevents the PDL cells from swelling and bursting, or shrinking and shriveling, which happens quickly in plain tap water. Tap water is hypotonic, causing water to rush into the cells and destroy them, making it one of the least desirable storage options.
Milk is also slightly acidic to neutral, which is compatible with cell health and helps maintain the integrity of the PDL tissue. Furthermore, milk contains minor nutrients such as proteins and carbohydrates that can temporarily sustain the cells and prevent their degeneration. While specialized solutions exist, pasteurized cow’s milk is typically sterile, readily available, and has proven significantly superior to alternatives like saliva or water for preserving cell viability for up to two hours.
Essential Handling and Immediate Next Steps
Acting quickly is paramount, and the first step after finding the avulsed tooth is to handle it correctly to avoid further damage to the root cells. You must only pick up the tooth by the crown, which is the white chewing surface, and never touch the root surface where the PDL cells are located. If the tooth is dirty, gently rinse it for a few seconds with milk or saline solution, but never scrub it or wipe it clean.
If the person is conscious and cooperative, the best action is to gently attempt to place the tooth back into its socket immediately. If this is not possible, the tooth should be immediately placed in a container of milk to prevent it from drying out. The container should be sealed and the patient should be transported to a dentist immediately.
The ultimate goal is to have the tooth replanted by a professional within 30 to 60 minutes of the injury for the highest chance of success. If milk is unavailable, the tooth can be held in the patient’s mouth between the cheek and gums, using the patient’s own saliva as a temporary, less ideal, storage medium.