There's no evidence that putting fluoride in the public water supply-as happens across the US and in some counties in the UK-prevents tooth decay in children, an independent report has concluded.
Although the rate of dental caries (tooth decay) has fallen consistently over the past 40 years, there are too many factors that could be responsible, say researchers from the Cochrane Collaboration.
And public health agencies may be basing their decision to fluoridate the public water supply on out-dated and biased data, the researchers say.
The Cochrane researchers found 155 studies that looked at the effects of fluoridation, but virtually all of them were biased, and many were so old that fluoride toothpaste hadn't even be introduced when they were carried out. They also failed to take into account other factors, such as reduced sugar consumption, other dietary changes, socio-economic status, and the use of other fluoride sources, such as toothpaste and floss.
Whatever the reason, tooth decay has certainly been on the decline in children. Since 1975, there's been an overall 35 per cent reduction in decayed, missing or filled baby teeth, while the number of children who don't have any decay has risen to 15 per cent.
The US started to fluoridate public water in 1945, and today around 25 countries follow the practise. In the UK, around 15 per cent of the public water is fluoridated, affecting around six million people.
(Source: Cochrane Collaboration, doi: 10.1002/14651858.CD010856.pub2)