A. lot. There is significant evidence from over 60 years that confirms that water fluoridation at recommended levels prevents dental decay.
New Zealand's most recent national oral health survey shows on average 40% less tooth decay experience for children in fluoridated areas than in those areas without it (New Zealand Oral Health Survey, Ministry of Health, 2009). The Australian National Survey of Adult Oral Health (2013) showed that adults experience 20-30% less tooth decay.
Many other international studies, and regional studies within New Zealand, have shown that children and adults living in areas with community water fluoridation have significantly lower tooth decay than people living in areas without it.
Fluoride already exists in water. It is topped up to levels that provide a benefit to teeth. At these carefully monitored levels, fluoride is safe and within the guidelines of the World Health Organization and other international public health agencies.
‘It is absolutely clear that at doses used in New Zealand to adjust the natural level to one that is consistent with beneficial effects (0.7–1.0 ppm), there is no risk from fluoride in the water.’Professor Sir Peter Gluckman, Chief Science Advisor, Office of the Prime Minister’s Science Advisory Committee.
In August 2014, the Royal Society of New Zealand and the Office of the Prime Minister's Chief Science Advisor jointly published the report Health Effects of Water Fluoridation: A Review of the Scientific Evidence. This report found that community water fluoridation within the range of concentrations currently recommended by the Ministry of Health and used in New Zealand poses no health risks, and the report also confirmed that there is compelling evidence of dental health benefits for New Zealanders.
Claims by opponents of water fluoridation that it leads to cancers, bone fractures and other serious conditions are not supported by evidence. Often the evidence quoted by opponents has been derived from studies where the levels of naturally occurring fluoride levels are so high that fluoride levels need to be reduced, such as some parts of China and the USA.
Organisations that endorse community water fluoridation include:
The only known side-effect of fluoridation at levels used in New Zealand is mild dental fluorosis, and it makes the teeth look whiter than normal enamel. It is visible to dental health professionals under close examination, and recent evidence from Australia indicates that this fades with time. There are no reported cases of disfiguring fluorosis associated with the fluoridating of water supplies in New Zealand.
The Ministry of Health’s New Zealand Oral Health Survey 2009 notes, ‘no significant differences in the prevalence of fluorosis...between people living in fluoridated areas and those in non-fluoridated areas’.
‘One side-effect of fluoride is for a portion of the population it causes minimal white mottling of the enamel...This is very rarely discernible and is definitely not the severe fluorosis that is so often pictured on websites of those opposed to fluoridation of the public water supply’Professor Sir Peter Gluckman, Chief Science Advisor, Office of the Prime Minister’s Science Advisory Committee
Keeping your teeth healthy also requires brushing twice a day with fluoride toothpaste, dental care and reducing sugar. Community water fluoridation provides additional benefits even if you do all these things. Over half of New Zealand adults avoid going to the dentist because of cost, and over half of New Zealand children don’t brush their teeth twice a day with the recommended strength fluoride toothpaste.
That’s why community water fluoridation is so important – it makes good oral health accessible to all.
There are different reasons why people oppose water fluoridation. These may include health concerns, not being aware of the benefits and wanting individual choice.
Communities can be confident that community water fluoridation is an effective and safe option. There is strong international evidence that there are no adverse effects of any significance arising from fluoridation at the levels used in New Zealand.
The World Health Organization recommends boosting fluoride to optimum levels and community water fluoridation as the best method to do this. Use of community water fluoridation in Australia and the USA has expanded. In some countries in Europe, the practicalities in adding fluoride to the water supply, mean that alternative methods are used to boost fluoride to optimal health levels – such as adding fluoride to salt or milk.