Dental caries remain a public health problem for many developing countries and for underprivileged populations in developed countries. This paper outlines the historical development of public health approaches to the use of fluoride and comments on their effectiveness. Early research and development was concerned with waterborne fluorides, both naturally occurring and added, and their effects on the prevalence and incidence of dental caries and dental fluorosis. In the latter half of the 20th century, the focus of research was on fluoride toothpastes and mouth rinses. More recently, systematic reviews summarizing these extensive databases have indicated that water fluoridation and fluoride toothpastes both substantially reduce the prevalence and incidence of dental caries. We present four case studies that illustrate the use of fluoride in modern public health practice, focusing on: recent water fluoridation schemes in California, USA; salt fluoridation in Jamaica; milk fluoridation in Chile; and the development of “affordable” fluoride toothpastes in Indonesia. Common themes are the concern to reduce demands for compliance with fluoride regimes that rely upon action by individuals and their families, and the issue of cost. We recommend that a community should use no more than one systemic fluoride (i.e. water or salt or milk fluoridation) combined with the use of fluoride toothpastes, and that the prevalence of dental fluorosis should be monitored in order to detect increases in or higher-than-acceptable levels.
*Original abstract online at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2626340/
Case study 2
Salt fluoridation in Jamaica
Salt fluoridation was introduced into Jamaica (population, 2.5 million) in 1987; all salt for human consumption is fluoridated (30). Fluoride toothpastes had been available in the country since 1972, and while their use may have had a protective effect (32), the notable decline in the prevalence of dental caries after 1984 may be considered to be primarily attributable to the introduction of fluoridated salt (27).
In 1984, a survey of oral health carried out by the Ministry of Health reported that Jamaican children had an alarmingly high incidence of dental caries (mean DMFT, 6.7 at age 12 years). Naturally occurring concentrations of fluoride in water were uniformly low (< 0.3 mg/l), but the complexities of the public water supplies ruled out water fluoridation as a measure to address these very high levels of disease. However, as there was only one producer of salt for the whole population, salt fluoridation seemed to be the ideal alternative.
After studies of household salt consumption, a recommendation to implement a salt fluoridation programme was widely endorsed, and was approved by the Parliament in 1986 (29). With technical assistance from the Pan American Health Organization (PAHO), salt was fluoridated using potassium fluoride at a concentration of 250 mg/kg. Studies of the urinary excretion of fluoride, conducted at baseline in 1987 and 20 months later, indicated that concentrations of fluoride were not above those associated with water fluoridation in temperate climates.
A national survey of oral health in 1995 confirmed striking reductions in the incidence of caries in all age groups (Table 1).
Jamaica’s salt fluoridation programme is apparently working well (29). As discussed above, salt fluoridation does not in general constrain consumer’s freedom of choice. Interestingly, however, because the only salt available on Jamaica is fluoridated, that advantage clearly does not apply in this case; nevertheless, fluoridated salt is apparently well accepted by the public.
Case study 3
Milk fluoridation project in Chile
In Chile, the National Complementary Feeding Programme (PNAC) was established by the government in the early 1960s. Under this programme, every Chilean child is entitled to receive 2 kg of powdered cows’ milk per month from birth until age 2 years, at no charge. After that, and until age 6 years, the child is eligible for 1 kg of milk–cereal product per month. The national coverage of this programme is around 90%. Although water fluoridation is practised extensively in Chile, it is not always practical or economic in rural communities. In 1994, the Institute of Nutrition and Food Technology of the University of Chile established a programme to assess the feasibility of using PNAC products as a vehicle for disodium monofluorophosphate. Studies of the bioavailability and absorption of fluoride derived from disodium monofluorophosphate in milk were undertaken. The community trial was undertaken in the rural community of Codegua, 100 km south of Santiago, with the similar community of La Punta, some 10 km from Codegua, being used as the control. The daily dose of fluoride from fluoridated powdered milk was 0.25 mg for infants aged 0–2 years, 0.5 mg for children aged 2–3 years and 0.75 mg for children aged 3–6 years. Results obtained after 4 years of milk fluoridation indicated
that it was possible to reduce the prevalence and severity of dental caries in the primary dentition, especially in those children either born after the start of the programme or aged around 1 year when it started. The fluoride programme did not cause an additional administrative burden on the existing programme for the distribution of powdered milk and milk-cereal. Termination of the programme resulted in a deterioration in the dental health of the children in Codegua. In 2002, 3 years after the programme ended, the prevalence of dental caries was higher than that recorded immediately after the end of the programme and was equivalent to that of the children in La Punta, the community that had been used as a control. The authors recommended the extension of milk fluoridation to other rural and semi-rural areas in Chile where water fluoridation was not technically feasible (39, 42).
Case study 4
Affordable toothpaste in Indonesia
The province of West Kalimantan, Indonesia, which had a relatively high prevalence of caries (DMFT, 7.15 for children aged 14 years in 1984–88), was selected as the setting for a WHO study to assess the efficacy of a toothpaste specifically manufactured as an “affordable fluoride-containing toothpaste” in a developing country with high prevalence of caries (47).
In 1990, major manufacturers of toothpaste were asked by WHO to consider producing an affordable fluoride toothpaste. Colgate-Palmolive was the first to bring forward a product ready for field testing, and in 1992 it was decided to conduct a school-based intervention study where the intervention group had one daily supervised tooth-brushing activity with the new affordable fluoride toothpaste, and the control group received no intervention.
Four primary schools in urban areas, and four in rural areas in each of three districts of the capital of the province, Pontianak, were selected for the study. Two urban and two rural schools in each district were allocated to the intervention group, while the remaining selected schools served as the control group, i.e. 12 schools receiving the intervention and 12 control schools in total. Baseline examinations of 2141 children aged from 6 to more than 10 years in the intervention and control groups were performed in 1993.
Children receiving the intervention carried out supervised brushing at school for at least one minute once a day using toothbrushes and the specially developed affordable toothpaste, containing fluoride at a concentration of 1000 mg/kg, supplied for the study. They were allowed to rinse with water only once after brushing. The study was evaluated after 3 years, and, in terms of caries, the DMFT increment in the children (all age groups combined) receiving the intervention was significantly (23%) less than in the children in the control group, with the younger age groups benefiting more than the older (children aged 8 years at baseline had a 40% lower DMFT increment).
This study demonstrated that it is possible to produce an affordable fluoride toothpaste that is effective in controlling caries. The study also demonstrated that, despite transportation problems and many other more urgent needs, given the commitment of the schools and the Ministry of Health, supervised school dental health programmes can also be effective in an area with “scarce resources and different living conditions” from those in which toothpaste trials are usually conducted (47). The next step of this evaluation should be to consider whether, if affordable fluoride toothpaste were to be marketed, what would be the uptake among populations that do not currently have access to, or make adequate use of, existing products.