The effective use of fluorides in public health

Jones, S., Burt, B.A., Petersen, P.E. and Lennon, M.A. (2005) Bulletin of the World Health Organization, 83 (9); 670-6.

A recently published World Health Organization (WHO) report stated that dental caries continue to cause significant public health problems in many developed and developing countries. This paper outlines the historical development of different public health approaches to the use of fluoride with comments on their effectiveness and examines four cases studies to illustrate their use in modern-day public health practice.

Research on fluoride effects and oral health began about 100 years ago. The first 50 years of research concerned the link between waterborne fluoride (natural and adjusted) and dental caries and dental fluorosis. The focus gradually changed then to the development and evaluation of fluoride toothpastes and mouth rinses and to a lesser degree, public health alternatives to water fluoridation. In more recent times, systematic reviews summarising large data sets have concluded that water fluoridation and fluoride toothpastes have both considerably reduced the prevalence and the incidence of dental caries.

A community water fluoridation programme was first introduced at Grand Rapids in the United States in 1945. Other community water fluoridation programmes followed. At present public water supplies in 43 out of the 50 largest cities in the US are fluoridated. Extensive fluoridation programmes have also been introduced worldwide. Systematic reviews of water fluoridation have concluded that water fluoridation reduces the prevalence of dental caries (defined as % of the population with decayed missing and filled primary teeth (dmft) and decayed missed and filled permanent teeth (DMFT) greater than 0) by an average of 15% and reduced the incidence of caries by an average of 2.3 dmft/DMFT in children aged 5-14 years. It has also been concluded that water fluoridation has benefits in addition to those found from just using fluoride toothpastes and there is no credible evidence that water fluoridation causes any adverse health effects. Water fluoridation with 1 mg/l is associated with an increase in risk of 13% of unaesthetic dental fluorosis. Some studies have suggested fluorosis is more likely to occur with naturally fluoridated waters than artificially fluoridated supplies.

Salt fluoridation is an alternative to water fluoridation and gives the consumer more choice over whether they consume the fluoridated product or not. The first studies on the incidence and prevalence of dental caries when fluoride was added to alimentary salt had results similar to those seen after the introduction of water fluoridation. It is not suggested that increased salt consumption be promoted to improve dental health, instead reduced salt consumption should still be encouraged and if salt consumption decreases, the concentration of fluoride in salt could be increased appropriately.

Fluoridation of milk is another alternative to provide the consumer with the public health benefits of fluoride without requiring a change in their behaviour or taking on particular responsibilities. Various avenues have been used to distribute fluoridated milk to children including: kindergarten and school programmes, powdered milk and milk-cereal distributed as part of the National Complementary Feeding Programme in Chile and taking of milk home from school for consumption over the weekend.

Fluoridation of toothpastes was introduced in the late 1960s and early 1970s is probably the most widespread and significant means of fluoride distribution. In developed countries the introduction of fluoride toothpastes is considered the factor most responsible for the massive reduction in dental caries seen in many countries during the 1970s and 1980s. The limitation to the effectiveness of fluoride toothpastes is whether the individual and the family purchase and regularly using the products. Uptake of fluoride toothpastes is less likely in the underprivileged and this contributes to different rates of tooth decay in different social classes. The WHO Oral Health Program has promoted the development and use of “affordable” fluoride toothpastes to try and overcome this problem.

In communities where the incidence and prevalence of dental caries is high to moderate or where the incidence is rising, an additional source of fluoride (water, salt or milk) should be considered along with the use of fluoride toothpastes. Water fluoridation is the method of choice when the country or area has a moderate level of economic and technological development and a municipal water supply reaching a large population with trained water engineers and a favourable public opinion. The prevalence of dental fluorosis should be monitored to detect increases or higher than acceptable levels and action taken when levels are not acceptable.