Topping up Fluoride in New Zealand

History

More than 70 years ago, dental researchers in the US noticed that people in some areas had much lower decay rates than their neighbours. Subsequently it was found that the difference was due to the levels of fluoride in the drinking-water. Those communities with low levels of fluoride had more tooth decay.

The use of topping up fluoride in water first began in New Zealand in Hastings in 1954. A Commission of Inquiry was held in 1957 and then its use rapidly expanded in the mid 1960s. The decision to add fluoride to water is made by local authorities who have the power to supply water for their district (section 379, Local Government Act 1974).  At present there are some 84 water supplies in the country that top up their fluoride.

The connection between dental decay and the amount of fluoride in water was first noted in the early part of the 1900s when it was observed that residents and immigrants of some parts of the US developed brown stains on their teeth. These stained teeth, although unsightly, were highly resistant to dental decay.

In the 1930s, researchers discovered that the prevalence and severity of this type of mottled enamel (dental fluorosis) was directly associated with the amount of fluoride found naturally in the water, in some areas as high as 13.7 parts per million (ppm). It was subsequently recognised that if fluoride in the water was at an optimal level of 0.7ppm to 1.2 ppm, teeth remained resistant to dental decay but were not stained.

The results of numerous studies in areas where fluoride has been added to water supplies at this optimal level, verify the effectiveness, safety, and economy of this public health measure in reducing dental decay.

Why top up fluoride levels?

The amount of fluoride occurring naturally in water is between 0.1 and 0.3 ppm. Topping up fluoride in a water supply to levels between 0.7 and 1.0 parts per million (ppm) offers the best protection against tooth decay. The amount added is constantly monitored to make sure that the levels stay within that range.

Water fluoridation is the process of adjusting the natural level of fluoride in the water supply to between 0.7 ppm and 1.0 ppm. This is the optimal amount that provides protection against tooth decay. The amount added is monitored to make sure that the levels stay within that range.

Along with brushing twice a day, eating healthy foods and timely check-ups with a dental provider, water fluoridation can have significant benefits to an individual.