The fluoride debate

Is fluoride good for your teeth, or a slow poison? We look at the most recent evidence.
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  • Updated:23 Feb 2007


Toothbrush and toothpaste

In brief

  • There’s now solid scientific evidence that fluoride added to drinking water helps to protect your teeth from decay.
  • The claims of those who oppose fluoridation are often based on outdated information, questionable research and selectively picking studies that support their case.
  • There’s no convincing evidence for harmful effects from fluoride at the levels used in our water supply.

Please note: this information was current as of February 2007 but is still a useful guide today.

Fluoride in drinking water

Beaconsfield, Tasmania, is famous for more than a mine rescue - in 1953 it was the first town in Australia to add fluoride to its water supply. Now every capital city has water fluoridation and, on average, Australians have much healthier teeth than 50 years ago.

To what extent is the improvement in Australians' dental health due to fluoride?

Health authorities are convinced of the dental health benefits of fluoride. A number of studies show that people exposed to fluoridated water are less likely to have decayed, filled or missing teeth than those who aren't (see The case for fluoridation).
Opponents continue to maintain that fluoride in the water supply does nothing to prevent tooth decay. And you’ve probably seen claims that it may in fact damage teeth by causing dental fluorosis, often with concerns that it may be adversely affecting our health in other ways (see Fluoride’s downside).

While still a controversial topic that can arouse strong passions, it’s now clear that the dental health benefits claimed for fluoridation are well supported by scientific evidence — and that the risks have been greatly exaggerated.

How does fluoride work?

Tooth decay (dental caries) begins when some of the enamel, the outer surface of the tooth, is destroyed by acid. The acid is produced by bacteria that can grow on the surfaces of teeth in a layer called plaque. When your teeth are exposed to foods or drinks containing sugars, the bacteria rapidly convert some of the sugars into acid. The plaque can hold the acid in contact with the tooth surface for up to two hours before it’s neutralised by saliva.

All the time that the enamel is exposed to acid it loses calcium and phosphate minerals into the plaque. Once the plaque acids have been neutralised the minerals can return to the enamel — a process called remineralisation. But the capacity for remineralisation is limited, so if you eat a series of sugary snacks through the day your natural defences don’t get enough time to do their stuff before the next assault on your tooth enamel. Fluoride helps to protect your teeth in at least three ways:

  • It promotes repair of early damage to the enamel.
  • It improves the chemical structure of the enamel, making it more resistant to acid attack.
  • It reduces the ability of the bacteria on your teeth to produce acid.

The verdict

Many people are less dependent on getting fluoride from water than in the past. Most people now use toothpaste that contains fluoride, and everyone’s exposed to fluoride in foods and drinks manufactured in fluoridated areas, the so-called ‘halo effect’.

But even though improvements in dental health from fluoridated water are now smaller, over the population as a whole they still represent a lot of teeth saved from decay.

Another plus from widely available fluoridated water is that it helps kids from lower socio-economic groups, who are at the greatest risk of tooth decay. They’re less likely to be regularly brushing their teeth, and even less likely to see a dentist.

What about bottled water?

Recent surveys have shown that tooth decay in Australian children is on the increase again. Experts are suggesting this coincides with the rise in popularity of bottled water and sports drinks that don’t contain fluoride (sugary juices and soft drinks are also likely culprits).

CHOICE and dental experts would like manufacturers to offer people the option of bottled water containing about 1 ppm of fluoride (the same as tap water in fluoridated areas).



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