If an adult permanent tooth has been knocked out, the next few minutes matter more than anything else you will do. The single most important thing is keeping the root wet. According to the International Association of Dental Traumatology's 2020 guidelines, once a tooth has been dry for about 30 minutes, most of the periodontal ligament cells on the root — the cells that allow it to reattach — are no longer viable. Dry time and total time are not the same thing: a tooth kept in milk for an hour is in far better condition than one left dry on a counter for half that time.
- Put the tooth back in the socket immediately if you can, at the scene.
- Handle it by the crown. Never touch the root.
- Do not scrub it, and never use soap.
- If you cannot reinsert it, store it in milk. Never in water.
- Do not reimplant a child's baby tooth — it can damage the permanent tooth developing above.
What to do right now
- Pick the tooth up by the crown — the chewing part you normally see. Never touch the root.
- If it is dirty, rinse it briefly with milk or saline. Do not scrub it, and do not use soap. The cells on the root surface are what allow reattachment, and scrubbing destroys them.
- Put it back in the socket the right way round, and bite gently on a clean cloth or gauze to hold it.
- If you cannot reinsert it, store it in milk. A tooth-preservation solution (Hank's Balanced Salt Solution) is better still if a first-aid kit has it. Saliva, held inside the cheek by an alert adult, is an acceptable fallback. Never store it in water — plain water kills the root cells quickly.
- Get to a dentist or an emergency room immediately. Call while you are travelling so they can prepare.
Also check for other injuries. A blow hard enough to knock out a tooth can fracture the jaw or cause a concussion. If there was loss of consciousness, confusion, vomiting, or a jaw that will not close properly, go to an emergency room.
Why the root must stay wet
The root of a tooth is covered in periodontal ligament cells, and those cells are what allow a replanted tooth to reattach to the bone. They are fragile — they do not survive drying, scrubbing, or plain water, which draws fluid out of the cells and destroys them. Every instruction here is really the same instruction: protect those cells. Replanting at the scene protects them best of all, which is why the guidance is to put the tooth back immediately rather than to travel with it if you are able.
Storage options, ranked
- 1. The socket itself. Immediate replantation gives the best outcome.
- 2. A tooth-preservation solution (Hank's Balanced Salt Solution), found in some first-aid and sports kits.
- 3. Milk. Widely available and effective. Ordinary cow's milk is fine.
- 4. Saliva, held inside the cheek — but only for an alert adult or older child who will not swallow it.
- Never water, and never a dry tissue, napkin, or paper towel. Wrapping a tooth dry is the fastest way to lose it.
Baby teeth are different
Do not put a knocked-out baby tooth back in. Replanting a primary tooth can damage the permanent tooth developing in the bone above it, affecting the shape, color, or eruption of the adult tooth that follows. Take your child to be seen — the socket and surrounding teeth still need examining — but leave the tooth out. If you are unsure whether a tooth is a baby or permanent one, bring it with you and let the dentist decide.
What happens at the dental office
If the tooth was replanted at the scene, its position is checked, it is splinted to the neighboring teeth for a period of weeks, and radiographs are taken. If it is arriving in storage, it is examined and replanted if the outlook justifies it. Root canal treatment is usually needed afterwards, often within a couple of weeks, because the blood supply to the pulp is severed when the tooth comes out. Replanted teeth are then monitored over months and years for resorption — some last decades, some do not, and follow-up is how problems get caught early.
One thing we tell patients plainly: replanting a tooth is worth attempting even when the outlook is uncertain. A replanted tooth that lasts several years preserves the bone and buys time — particularly for a younger patient, where an implant is not appropriate until growth is complete.
Myth vs fact
- Myth: Store the tooth in water. Fact: Water destroys the root cells. Milk, saline, or a tooth-preservation solution — never plain water.
- Myth: Clean the tooth thoroughly before putting it back. Fact: Scrubbing removes the cells that make reattachment possible. Rinse briefly, nothing more.
- Myth: Put a baby tooth back the same way. Fact: Never. It risks damaging the developing permanent tooth.
- Myth: If it has been more than an hour, there is no point. Fact: The outcome is poorer, but a tooth kept moist can still sometimes be replanted, and there is more to attend to than the tooth itself.
When to see a dentist
Immediately for any knocked-out permanent tooth — call while travelling. Same day for a knocked-out baby tooth (do not replant it, but have the child examined). Go to an emergency room if there was loss of consciousness, confusion or vomiting, a jaw that will not close properly, uncontrolled bleeding, or significant facial injury.
Summary
Put the tooth back in the socket immediately if you can, handling it only by the crown. If you cannot, store it in milk — never water — and get to a dentist right away. After about 30 minutes of dry time, the cells that allow reattachment are largely gone, which is why keeping the root wet matters more than anything else. For a child's baby tooth, do the opposite: leave it out, and have the child seen.