 Fluoride use has had an interesting evolution to its current status as an aid to oral health.
The first systematic examinations of fluorides in water came in the early 1930s with attempts in the United States to find the reason behind brown stains and tooth mottling (fluorosis) – the subject of research and speculation for many years in some towns. Tests in 1931 confirmed unusually high levels of fluoride in the water supplies of every district where the staining was considered a problem. Further tests showed the extent of the stain increased with the amount of fluoride in the water. From about 2.0 to 13.7 ppm the stain increased in intensity in accordance with the level of fluoride. However, below 1.0 ppm no significant fluorosis was observed.
In 1936 Dr H. Trendley Dean completed the first scientifically reliable studies on fluoride levels, tooth mottling and decay prevention. A decade later, a multi-disciplinary medical-dental team proved the benefits of water fluoridation by forming the Newburgh-Kingston study in 1945, when the water supplies of US cities Newburgh and Kingston were topped up with fluoride to 1.0 ppm. The team had hoped to study the results for 10 years, but initial interest in the positive results was so high that by 1949 moves were made to fluoridate other cities’ water supplies.
In New Zealand, Hastings was the first municipality to adjust the fluoride level in its water, in 1954. Following the introduction of the practice, a Commission of Inquiry was held in 1957. A positive result from the inquiry led to widespread water fluoridation throughout New Zealand. Today, in 84 water supplies serving more than half (approx 57%) the population, fluoride levels have been topped up to between 0.7 and 1.0 ppm.
Over time, the apparent benefits of water fluoridation appear to have diminished. Children in fluoridated areas now have 15-20% less tooth decay than those in non-fluoridated centres, compared with 30% lower decay levels in the early decades. However, this difference is more apparent than real with, the introduction of fluoride toothpaste, major manufacturing centres such as Auckland using fluoridated water for canning, drink manufacture, soups and other liquids in prepared foods, and the high mobility of many families who move into and out of fluoridated areas.
But real benefits remain, with no evidence of harmful side effects in areas that have enjoyed water fluoridation for several generations.
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