White, Yellow, Brown or Black Spots on Your Child's Teeth

"There's a mark on her tooth that won't brush off." Parents often send us photos like this, and they are right to ask. Some spots are early decay that is easiest to treat when caught early. Others are harmless stains or a difference in how the enamel formed. The colour, the place and whether it brushes away all give useful clues, but a dentist's examination is the only way to be sure.

White spots

• Chalky white lines near the gums. On baby teeth or adult teeth, a dull, chalky band along the gum line is often the earliest sign of decay, where acid has started to weaken the enamel. At this stage it can sometimes be stopped, or even partly repaired, with better brushing, fluoride and fewer sugary snacks, before a hole forms.
• Faint white streaks or flecks across the tooth. These may be mild fluorosis, which can happen when a young child swallows more fluoride than needed while the adult teeth are forming, often from too much toothpaste. Mild fluorosis is usually cosmetic only. It is a good reason to use the right amount of toothpaste: a rice-grain smear under 3, a pea-sized amount from 3 to 6, and spitting rather than swallowing.
• A single white or creamy patch on one tooth. This may be a spot where the enamel did not form fully, sometimes after an injury or infection of the baby tooth above it.

White, yellow or brown patches on new adult molars

If your child's first adult molars (which appear around age 6) or front teeth come in with cream, yellow or brown patches that look "built into" the tooth, this may be MIH (molar incisor hypomineralisation). In MIH, parts of the enamel are softer and more porous than normal. It is not caused by anything the parents did, and its exact cause is still being studied.

Teeth with MIH can be:

• Sensitive to cold, air or brushing, so some children avoid brushing that area.
• More prone to decay and chipping, because the weaker enamel can break down after the tooth comes in.

Early care helps. Depending on the tooth, your dentist may suggest fluoride varnish, protective sealants or coatings, desensitising toothpaste, or a covering such as a filling or crown for teeth that break down. Regular check-ups are especially important for these teeth.

Brown or black marks

• Decay. A brown or black spot, especially in the grooves of back teeth or between teeth, may be a cavity. If it is soft, rough, catches food or causes pain, book a check soon.
• Black line stain. A thin line of black or dark dots running along the teeth near the gums is usually a harmless stain made by certain mouth bacteria. It often comes back after cleaning, and interestingly, children with this stain tend to have fewer cavities. A dentist can polish it away.
• Iron supplements. Liquid iron drops can leave a dark grey or black film. Ask your doctor whether it can be given with a syringe towards the back of the mouth, and brush or rinse with water afterwards. The stain is on the surface and can be polished.
• Drinks and foods. Tea, some medicines and strongly coloured foods can stain the surface over time.
• SDF (silver diamine fluoride). If your child has had SDF to stop a cavity, the treated area turns black. This is expected, and means the treatment has reacted with the decay. Your dentist will have discussed this beforehand.

A grey, dark or pink tooth after an injury

A front tooth that turns grey, dark yellow or pinkish days, weeks or even months after a knock may mean the nerve inside has been affected. Sometimes the colour fades with time, but the tooth should be checked, and possibly X-rayed, to look for infection. Swelling or a "pimple" on the gum above it needs a visit soon.

Please avoid whitening products

Whitening strips, gels and "whitening" toothpastes are not recommended for children. They can irritate gums, cause sensitivity, and will not fix decay, MIH or enamel defects. Most surface stains are best removed with a professional polish.

When to book a check

• A white, brown or black spot that is new or getting bigger
• A rough, soft or chipped area, or a hole
• Sensitivity, pain, or your child avoiding brushing one area
• A tooth that changes colour after a fall
• Swelling of the gum or face (swelling with fever needs urgent attention)