This week, Alan Johnson, the Health Secretary, called for fluoride to be added to more areas of England’s water supply, to prevent dental decay. In passing, he acknowledged that, for all the benefits of fluoride, too much can lead to a permanent discolouring of the teeth, called dental fluorosis. But only, he said, when children “ate toothpaste”.

Toothpaste causing bad teeth? It seems illogical, particularly since dentists so fervently urge us to use it. But many parents are unaware of the potential risks of letting children under 7 swallow fluoride toothpaste, especially in fluoridated areas, where they are already receiving a background dose of the chemical.

They might also not know that dental fluorosis appears to be on the rise, according to government-backed research from the University of York. This indicated that, while increasing use of fluoride toothpastes has cut the average number of decayed teeth per child from nine to two in 20 years, 48 per cent of children in areas of fluoridated water, and 15 per cent in nonfluoridated areas, show some traces of fluorosis.

Awareness of fluorosis is low

Even dental teams are unaware of the dangers. Richard Harrison, a clinical dental technician from Barnsley, a fluoridated area, certainly wasn’t aware that his seven-year old daugher might be at risk of fluorosis. But as soon as her second teeth started to come through, he saw they were mottled and brown-stained with white flecks – the classic sign of dental fluorosis. Too much exposure to fluoride while the second teeth are developing beneath the milk teeth makes their enamel porous, something that doesn’t become apparent until the teeth break though. In mild cases, this leads just to a pearly sheen to the teeth. In bad cases there can be staining, chipping and pitting of the tooth.

“She always loved strawberry-flavour toothpaste, so she may have swallowed it,” Harrison says. “Our biggest fear is how other children will respond to the way she looks.” The effects of dental fluorosis are irreversible, although it can be covered up with expensive tooth veneers when children reach their early teens.

The irony is that, while the politicians are rightly concerned about addressing poor dental health in deprived areas through fluoridation schemes, it is families who are most conscientious about their children’s health that may be most affected by fluorosis.

Jane, a dental nurse from the West of England, has two daughters with suspected fluorosis, and is so worried about the potential effect on them that she doesn’t want to be identified. “It’s a massive guilt trip,” she says, deeply upset that she never got her girls to rinse out the toothpaste when they had finished brushing.

Her eldest daughter, 9, has minimal signs of fluorosis, but her youngest, 7, has very mottled front teeth. Jane believes the difference between the two children can be put down to moving to a fluoridated area when the youngest was two-and-a-half – a crucial time for tooth development.

“I religiously brushed their teeth thinking that I was doing the right thing,” says Jane, who also feeds her children organic food to keep them healthy. “But I’m convinced it’s the toothpaste. I don’t think people are aware of how bad it is to swallow it. I didn’t realise – and I’m a dental nurse, for God’s sake.”

Psychological damage

She is also worried about the taunting her child is likely to get at school. Research about to be published by Cardiff University indicates that children with obvious dental fluorosis are more likely to be viewed on first appearance as less pleasant and less intelligent. Fluorosis may not be life-threatening, but there are social and psychological effects which are hard to quantify.

Because of fluoride’s undoubted contribution to reducing tooth decay, British dentists have been united in promoting the mineral, which occurs naturally in some water supplies. At the right dose, it makes enamel more resistant to acid and inhibits bacteria. The British Dental Association says the development of ranges of toothpaste for children in the early 1990s has reduced the likelihood of overdosing on fluoride.

But this week, Ann Keen, a health minister, told Parliament that dental fluorosis “is often caused by very young children swallowing fluoride toothpaste unsupervised”. This seems to put the onus on parents– the problem being that the messages they receive are not always clear. The document Delivering Better Oral Health, issued to all NHS practices in November 2007, recommends what most parents already know: using a pea-sized amount of toothpaste, and using a toothpaste with the right concentration of fluoride for your child’s age group. But nowhere does it suggest that dentists should explain to them any risk associated with ingesting too much fluoride. Of the half dozen families affected by fluorosis contacted by Body& Soul, all felt surprised that their dentists had never mentioned fluorosis to them.

Delivering Better Oral Health recommends that most under6s use a toothpaste with a fluoride concentration of 1,350 to 1,500 parts per million (ppm). This is considerably stronger than the 1,000ppm toothpaste recommended by other NHS health promotion material. Some popular child toothpastes have a fluoride content of 500ppm, others of 1,100ppm.

The document also recommends that children spit out their toothpaste but don’t rinse, leaving some fluoride in the mouth so that it has the full protective effect on teeth. This contradicts the advice of dentists contacted by Body&Soul, who said that they would recommend rinsing to minimise fluorosis risk.

Too much of a good thing

How much do children have to swallow for there to be a risk of fluorosis? The answer may be on a knife edge. As a Medical Research Council working group reported in 2002: “Fluoride has a relatively low ‘therapeutic ratio’ [the ratio between an effective dose and a toxic dose].” There could be a fine line between doing good and doing bad. The reason for the mixed messages may lie in the lack of clear answers from research. The Medical Research Council working group concluded that “there have been too few studies of total fluoride intake and the contribution of various sources to that intake” and “more robust information on the potential harms of fluoride is needed”. This followed the University of York view that found little conclusive evidence on the benefits or safety of fluoridation. Acknowledging this, the Government said in 2002 that it was committed to improving research on fluorosis. But progress is slow.

Six years later, the Department of Health says a report investigating the best ways to assess the extent of fluorosis will be published later this year. Depending on the results of this research, it may commission further research into public perceptions of fluorosis.

Meanwhile, parents such as Richard Harrison and Jane are puzzled about why toothpaste makers don’t have more prominent warnings on their tubes. In America, an advice panel on how to use the toothpaste is accompanied by: “Warning: keep out of reach of children under 6 years. If you accidentally swallow more than used for brushing, seek professional assistance or contact a Poison Control Center immediately.”

Parents are also puzzled about why, if there is a risk from swallowing toothpaste, manufacturers make their products taste like sweets. Professor Ivor Chestnutt, honorary consultant in dental public health at the Cardiff University School of Dentistry, agrees. He believes it would be wrong to scare people away from fluoride toothpaste, such are its benefits, but says: “The one thing I would be against is bubble-gum and fruit-flavoured toothpastes, which encourage children to eat them.”

The Oral-B Stages toothpaste range for childrenincludes Fruit Blast and Berry Bubble flavours. The manufacturer Procter & Gamble emphasises that “any overdosing on fluoride would need to be regular and over a prolonged period of time”. A spokesman said: “The use of fruit-flavour toothpaste encourages brushing, which helps promote dental health. It will also increase levels of ingestion, but this is not a concern, as data demonstrates there is no risk to children using pastes with up to 1,500ppm.” Oral-B Stages child toothpaste has 500ppm.

Whether the facts are this clearcut may be debated by families affected by fluorosis. Definitive research providing the answers may be a way off. In the meantime, some good and honest communication between professionals and the public could go a long way.

“I was tormented at school because of my brown teeth”

Lisa Wain from Mansfield was 10 when, after three years of taunting and teasing at school because of her brown teeth, she had veneers put over her front top teeth. She had received a diagnosis of dental fluorosis, having swallowed toothpaste since early childhood, and been initially told by a dentist that she simply had dirty teeth.

Looking back, Lisa, now 23, says her self-confidence started to come back as soon as she got her new white teeth. But, beyond the initial expense, they have caused problems. She pays higher premiums on her dental insurance policy because of the risks of her veneers coming off. “I had to have one replaced a few years ago because it got chipped, and another one fell off.”

Brush safely

Department of Health advice for children under 7:

Brush last thing at night and on one other occasion.

Brushing should be supervised by an adult.

Use a pea-sized amount of toothpaste containing 1,350-1,500ppm fluoride.

Spit out after brushing and do not rinse.

Times recommends

• It is possible to look stylish while pregnant
• Britain’s tot models
• Who and what benefits from the heat wave?