why is my child tooth grey after a fall

Toddlers fall constantly, and the upper front milk teeth take most of the knocks. Often the tooth looks fine at first. Then, days or weeks later, parents notice it has turned pink, grey, dark yellow or almost black compared with its neighbours.

Why the colour changes

Inside every tooth is the pulp (the nerve and blood supply). A knock can rupture tiny blood vessels inside it, like a bruise you cannot see. Blood breakdown products seep into the microscopic tubes of the dentine (the layer under the enamel) and show through as pink, then grey. From here, one of three things tends to happen:

• The pulp recovers. The colour may fade partly or fully over weeks to months. Sometimes the tooth turns yellowish instead, as the pulp lays down extra hard tissue inside. This is usually harmless.
• The pulp dies but stays quiet. The tooth stays grey, with no infection, pain or swelling. With milk teeth, a dentist may simply watch this with regular checks.
• The dead pulp becomes infected. This is the one to catch. Bacteria can multiply inside the tooth and cause an abscess at the root tip.

Warning signs of infection

• a pimple or boil on the gum above the tooth, which may leak pus
• swelling of the gum, lip or face
• pain, especially when biting or at night
• the tooth becoming loose again after it had firmed up
• fever with any of the above

If your child has swelling spreading towards the eye, or difficulty swallowing or breathing, treat it as an emergency and go to a hospital emergency department if a dentist is not immediately available.

What the dentist will check

The dentist will examine the tooth and gum, test how loose it is, and usually take a small digital X-ray to look at the root and the bone around it. Because the adult tooth develops right behind the root of a milk tooth, the X-ray also shows whether infection is threatening it. A single "it looks fine" visit is not enough. Injured teeth are usually reviewed over several months, because problems can show up late.

Treatment options

For a milk tooth:

• No treatment, just regular review, if there is no infection.
• A pulpectomy (a children's version of root canal treatment) if the pulp is infected and the tooth is worth keeping.
• Extraction if infection is spreading or the tooth is close to falling out naturally. The adult tooth's health comes first.

For an adult tooth in an older child, a dead or infected pulp needs root canal treatment. In children of around seven to ten, the root may not have finished growing, and the specialist may use techniques designed for immature roots. Teeth that stay discoloured after treatment can often be lightened or covered later, once the child is older.

What not to do

Don't assume grey means the tooth will soon fall out on its own, and don't wait for pain. Many infected milk teeth cause children no pain at all until a swelling appears. Tell the dentist about the fall even if it was weeks ago; it helps them read the X-ray.

For children under 10, see our MDS Pedodontics department; for root canal care on adult teeth, see our Endodontics department. Read more on our dead tooth page.