How to Tell a Baby Tooth From a Permanent Tooth

If a tooth has come out, this matters more than it might seem: never put a baby tooth back in, but put a permanent tooth back in if possible. Getting this wrong is the single biggest mistake in dental trauma first aid. Here’s how to tell the two apart quickly.

Is it a baby tooth or a permanent tooth?

Is the child under 6?
→ Almost certainly a baby tooth. See what to do if a baby tooth is knocked out.

Is the child 12 or older?
→ Usually a permanent tooth by this age. See what to do if a permanent tooth is knocked out.

Between 6 and 12?
→ This is the mixed-dentition stage — children have both baby and permanent teeth at once, so age alone won’t tell you. Check size, colour and the neighbouring teeth below.
→ Still unsure after checking? See “If you’re still unsure” further down.

How to check

A useful clue: what else is in the mouth

Look at the teeth either side of the gap. If the neighbouring teeth are clearly a mix of sizes — some noticeably bigger than others — the child is in the mixed-dentition stage, and you can’t rule out either type on age alone. If every visible tooth looks a similar, larger adult size, a freshly lost tooth is more likely to be permanent.

If you’re still unsure

This isn’t a situation where guessing wrong is a small mistake — but it’s also not a situation to guess your way through. If there’s genuine doubt after checking the above:

• Don’t attempt to replant the tooth without professional advice.
• Keep the tooth safe, in case a dentist wants to see it.
• Have a dentist check the child as soon as reasonably possible — they can confirm which type it is, often just by looking at the socket.

What to do next

• If you’ve confirmed it’s a permanent tooth: see what to do if a permanent tooth is knocked out — acting quickly matters here.
• If you’ve confirmed it’s a baby tooth, or you’re not sure: see what to do if a baby tooth is knocked out — this is a slower-paced situation, but still needs a dentist to check it.
• Either way, if you’re unsure where to get help: see dentist, NHS 111, A&E or 999 — where to get help for a dental injury.

Print this before you need it

A Baby or Permanent Tooth? quick-reference card is coming to the Download Centre — a phone-saveable and printable version of the comparison above. In the meantime, the Knocked-Out Tooth Poster covers the permanent-tooth emergency steps. Download free

Frequently Asked Questions

How can I tell if it’s a baby tooth or an adult tooth?

Baby teeth are smaller and whiter, with a full set of 20 typically in place by age 3. Adult teeth are larger and slightly more yellow-white, starting to come through from around age 6.

Why does it matter which type of tooth was injured?

The first aid response is different. Adult teeth can sometimes be saved and re-implanted, while baby teeth are never put back in — but both still need a dentist to check for damage to the root or the tooth developing underneath.

At what age do children start losing baby teeth?

Most children start losing baby teeth around age 6, usually starting with the lower front teeth, with the process continuing until around age 12.

Should a knocked-out baby tooth be put back in?

No. Re-inserting a baby tooth can damage the permanent tooth forming underneath. Instead, keep your child calm, control any bleeding, and see a dentist to check the area.

Do baby tooth injuries affect the adult tooth underneath?

They can. A hard knock to a baby tooth can sometimes affect the developing adult tooth beneath it, which is why any dental injury in a young child should be checked by a dentist, even if the baby tooth itself seems fine.

References

• International Association of Dental Traumatology (IADT), Guidelines for the Management of Traumatic Dental Injuries, 2020 (current as of August 2026)
• NHS, Knocked-out tooth, nhs.uk

This guide does not replace assessment by a dentist or emergency service. It reflects current international and UK guidance, reviewed by Dr Yousuf Ibrahim, BDS.