Dental avulsion, commonly known as a knocked-out tooth, is one of the most severe dental injuries and requires immediate attention to save the tooth. This complete displacement of the tooth from its socket severs the blood and nerve supply, creating a time-sensitive emergency. The long-term survival of the tooth depends entirely on the viability of the periodontal ligament (PDL) cells, the living tissue fibers attached to the root surface. Successful reimplantation is directly tied to how quickly and effectively the tooth is handled and preserved before reaching a dental professional.
Immediate Handling and Preparation
The moment a permanent tooth is avulsed, the priority is to prevent the root surface from drying out and to avoid damaging the delicate PDL cells. The first step involves locating the tooth and picking it up only by the crown. Avoid touching the root, as this could destroy the remaining viable ligament fibers essential for reattachment to the jawbone.
If the tooth is visibly dirty, gently rinse it for no more than ten seconds under cold, running water or, ideally, sterile saline solution. This quick rinse is only to remove gross debris; it is crucial not to scrub, brush, or wipe the root surface, as this action will strip away the vital PDL cells. Once cleaned, if the patient is calm and cooperative, the best action is immediate replantation by gently pushing the tooth back into its socket.
A distinction must be made between permanent teeth, which should be preserved and replanted, and primary (baby) teeth. Primary teeth should never be replanted because doing so risks damaging the developing permanent tooth bud underneath. If a permanent tooth has been replanted, the patient should bite down gently on gauze or a clean cloth to hold it in position while seeking urgent professional care. If immediate replantation is not possible, the tooth must be placed in a suitable preservation medium right away.
Selecting the Best Preservation Medium
If immediate replantation is not feasible, the choice of storage medium becomes the most important factor for maintaining the viability of the PDL cells. The ideal solution must mimic the body’s environment, specifically matching the physiological pH and osmolality to prevent cell swelling or shrinkage. Specialized commercially available systems, such as Hank’s Balanced Salt Solution (HBSS), are considered the gold standard because they are specifically formulated to sustain cell life for extended periods.
However, because these commercial kits are rarely available at the time of injury, cold milk is the most recommended and accessible alternative. Cold pasteurized milk offers a favorable osmolality of approximately 270 mOsm/kg and has a near-neutral pH of 6.5 to 7.2. These characteristics allow milk to prevent rapid cell death and maintain PDL cell viability for up to two hours.
If milk is unavailable, the tooth can be stored in the patient’s own saliva, such as inside the cheek (buccal vestibule), but this should only be done for older children or adults who are conscious and unlikely to swallow the tooth. Saliva is less ideal than milk due to its microbial contamination and non-physiological osmolality, which can damage the cells if used for longer than an hour. Plain tap water should be avoided entirely, as its low osmolality causes rapid swelling and lysis (bursting) of the PDL cells, drastically reducing the chance of successful reattachment.
Urgent Professional Treatment
Regardless of the preservation method used, the prognosis is directly tied to the total time the tooth is outside the socket, often called the “golden hour.” The highest success rates for long-term tooth survival occur when the tooth is reimplanted within 60 minutes of the injury. Beyond this timeframe, the chances of the PDL cells remaining viable decrease significantly, leading to complications like root resorption or ankylosis.
Upon arrival, the professional will assess the tooth and the socket, which may involve gently rinsing the empty socket with sterile saline to remove blood clots. The tooth will then be gently repositioned and stabilized using a flexible splint, typically made of wire and composite resin, bonded to the adjacent teeth. This splint allows slight, natural movement of the tooth and is usually kept in place for one to two weeks.
For teeth with a closed apex (fully formed root), the severed blood supply means the pulp tissue inside the tooth will not survive. Therefore, root canal treatment is necessary and is generally initiated seven to ten days after the replantation, before the splint is removed. Post-reimplantation care includes maintaining a soft diet during the splinting period, administering systemic antibiotics in some cases, and close monitoring for signs of healing or complications.