The colour of a mark on a child's tooth says a lot about where it came from. Black dots near the gums, a yellow film, a single grey front tooth and chalky white patches each point to different causes, and only some of them will polish off. Most staining in children turns out to be on the surface, but a few colours are worth a dentist's look.
Two places a stain can sit
A stain is either on the outer surface of the enamel or built into the tooth itself. Surface stains come from things that touch the teeth, such as plaque, drinks, medicines and supplements, and a professional clean can usually lift them. Internal stains form while the tooth is developing or after an injury, so brushing and polishing will not change them. The same principle applies to adults, which our article on coffee, tea and wine stains covers.
Black or dark brown marks
Two causes account for many of these. Liquid iron supplements can leave a dark film on baby teeth. It looks dramatic but sits on the surface rather than inside the tooth.
The other is a condition dentists call black stain: a thin line of tiny dark dots running along the teeth just above the gum. A 2024 review in the Journal of Dental Sciences (Dong and colleagues) describes it as a special type of dental plaque linked to particular mouth bacteria, notes that it cannot be cleaned off at home and needs professional removal, and points out that it tends to form again. The exact cause is still not settled. Many children therefore need it removed again from time to time.
A yellow or brown film near the gums
This is usually plaque that has been sitting on the teeth long enough to pick up colour from food and drink. It is a common stain in children and one of the easiest to change, because better brushing along the gum line removes the plaque that holds the colour. If the area is chalky or rough rather than a film, it may be early decay instead, which needs a dentist's opinion.
One tooth turning grey
A single baby front tooth that darkens to grey after a knock deserves attention, even if the child has no pain and the knock happened weeks or months earlier. In a study of 48 injured baby incisors with dark grey discolouration and no other signs of a problem, Holan and Fuks (Pediatric Dentistry, 1996) found that nearly all had a dead or partly dead nerve when treated. A dentist can examine the tooth, check for infection and plan how to monitor or treat it.
White flecks, lines or patches
Faint white flecks or streaks on adult teeth can be mild fluorosis, which happens when a child takes in more fluoride than needed while the teeth are forming, usually from swallowing toothpaste. Using the right amount of paste helps prevent it, and our guide to fluoride toothpaste for children explains how much to use at each age.
White or creamy yellow to brown patches that are chalky, rough or break down easily are different. They can be early decay or a developmental enamel defect such as molar incisor hypomineralisation, which affects the first adult molars and often the front teeth. These teeth may be sensitive and more prone to decay, so they are worth having checked.
Green, grey or banded teeth
These are uncommon and come from inside the tooth. Green colouring of the teeth has been reported in children who had high bilirubin levels, for example from severe newborn jaundice or liver disease. Older tetracycline antibiotics given while teeth are forming are known for causing permanent grey or brown staining; a 2026 review in the journal Children (Machuca-Portillo and colleagues) found that short courses of the newer drug doxycycline appear to carry little or no risk of this in children under eight, although the evidence is still limited. Rare inherited conditions of the enamel or dentine can also change tooth colour. None of these will polish away, and a dentist can explain what options exist as the child grows.
Keeping surface stains down at home
The Australian Dental Association advises starting toothpaste at 18 months, then brushing twice a day, with a parent helping or checking until the child can do it well. If your child takes liquid iron, ask the prescriber how best to give it and brush or wipe the teeth afterwards. Cordial, juice and coloured soft drinks between meals add colour and sugar, so water is the better everyday drink. Store bought whitening products are not suitable for children; if an older child is unhappy with the colour of their teeth, our article on whitening for teenagers explains the cautions.
Questions about stains on children's teeth
Will a professional clean make my child's teeth white again?
It can remove surface stain from plaque, iron drops and black stain, although black stain often returns. It will not change internal colour.
Are stained teeth more likely to decay?
Surface stain on its own is mostly cosmetic. Chalky white or brown patches are different, because they can be early decay or weaker enamel, and protective steps such as fissure sealants may be suggested.
A routine visit is the easiest time to have any colour change looked at. If your child is new to the dentist, our guide to the first dental visit sets out what happens, and our current new patient offers show how to book with a dentist or OHT at Lumi Dental.
