The Dawn of a New Era

This paper reviews the scientific events culminating in the fluoridation of communal water supplies. Dental and medical studies completed by 1942 had established the safety and benefits of exposure to drinking water naturally containing fluoride. Researchers and public health workers concluded that it was possible to test the hypothesis that the dental benefits attained where fluoride levels around 1 ppm occurred naturally in drinking water could be safely replicated in low-fluoride areas by raising the level to this optimal concentration. Grand Rapids became the first test site and by the time the demonstration ended in 1959, around 40 million people in about 2,000 communities already were drinking water with fluoride levels that had been adjusted to optimal. The success of fluoridation brought the dawn of the era of caries control and created great opportunities for research and public health.     

Water fluoridation: current effectiveness and dental fluorosis

Abstract – This paper reviewed the literature on the evidence for water fluoridation's effectiveness under current conditions of multiple fluoride use at recommended and at reduced concentrations, the extent of dental fluorosis at different fluoride concentrations, and the "halo" effect of water fluoridation. Using the relative difference in dental caries between communities with low and optimal water fluoride as an indicator, the effectiveness of water fluoridation has decreased over time as the use of other fluorides has increased. Thus the effectiveness of water fluoridation alone cannot now be determined. Compared to the early fluoridation studies, the differences in dental caries and fluorosis prevalence between fluoridated and non-fluoridated areas have markedly narrowed. Both the prevalence and severity of dental fluorosis have increased since 1945; however, the portion of fluorosis due to water fluoridation is now less (40%) than that attributed to other fluoride sources (60%). Research also suggests that the "halo" effect of community water fluoridation may result in a significantly greater intake of fluoride for people in non-fluoridated communities. This review recognized that since water fluoridation has unique advantages from the perspectives of distribution, equity, compliance and cost-effectiveness over other fluoride technologies, it remains as the fundamental base for caries prevention. The increasingly greater contribution that other sources of fluoride make to dental fluorosis suggests that these sources of fluoride, many of which arc used on an elective basis, should be more closely examined for needed changes.     

Decision-making for national programs of community fluoride use

Every community, region or country with a high or rising prevalence of dental caries should implement a caries-preventive program that automatically brings the benefits of systemic and topically applied fluoride to the entire population. The fluoridation of community water supplies or salt fulfills the requirements of providing safe, effective protection from dental caries at reasonable cost. The use of dietary fluoride supplements or fluoridated milk does not meet the requirements of a comprehensive national or community program because compliance is poor or only selected age groups are targeted. Water fluoridation is ideal for countries, regions or communities with many central water supplies or where salt production or distribution is not centralized or easy to control. Water fluoridation also has advantages where many areas exist with natural water fluoride concentrations at optimal or greater than optimal concentrations. Salt fluoridation is ideal for countries or regions with few, potable central water supplies in which salt production and distribution are centralized and easily controlled. Concentrations of fluoride for water fluoridation range from 0.5 to 1.2 parts per million (ppm) parts of water depending on climate and dietary practices. The concentration for fluoridation of salt is approximately 200 to 250 mg fluoride per kg of salt, also depending on dietary practices. Properly fluoridated salt should produce levels of urinary fluoride excretion similar to those found in communities with fluoridated water. Benefits of the two methods are similar. Salt fluoridation may be done more cheaply.     

Effectiveness of Water Fluoridation

The efficacy of communal water fluoridation in reducing dental caries has been reviewed based on surveys conducted in the last decade of caries prevalence in fluoridated and nonfluoridated communities in the United States as well as in Australia, Britain, Canada, Ireland, and New Zealand. The efficacy is greatest for the deciduous dentition, with a range of 30–60 percent less caries in fluoridated communities. In the mixed dentition (ages 8 to 12), the efficacy is more variable, about 20–40 percent less caries. In adolescents (ages 14–17), it is about 15–35 percent less caries. Current data on caries prevalence in adults and seniors are extremely limited and include several populations living in communities with higher than optimal fluoride levels. For these adults and seniors, a range of 15–35 percent less caries would also apply. Viewed in toto, the current data for children, adolescents, adults and seniors show a consistently and substantially lower caries prevalence in fluoridated communities. For an accurate measurement of the efficacy of water fluoridation in reducing dental caries, it is essential that only persons with a record of continuous or long-term residency in fluoridated versus nonfluoridated areas be included in such assessments. Because of the high geographic mobility in our society and the widespread use of fluoride dentifrices, supplements, and other topical fluoride agents, such comparisons are becoming more difficult to conduct. Accordingly, the effectiveness (rather than the efficacy) of water fluoridation has decreased as the benefits of other forms of fluoride have spread to communities lacking optimal water fluoridation.     

An economic evaluation of community water fluoridation

OBJECTIVE: The purpose of this research was to assess the local cost savings resulting from community water fluoridation, given current exposure levels to other fluoride sources. METHODS: Adopting a societal perspective and using a discount rate of 4 percent, we compared the annual per person cost of fluoridation with the cost of averted disease and productivity losses. The latter was the product of annual dental caries increment in nonfluoridated communities, fluoridation effectiveness, and the discounted lifetime cost of treating a carious tooth surface. We obtained or imputed all parameters from published studies and national surveys. We conducted one-way and three-way sensitivity analyses. RESULTS: With base-case assumptions, the annual per person cost savings resulting from fluoridation ranged from $15.95 in very small communities to $18.62 in large communities. Fluoridation was still cost saving for communities of any size if we allowed increment, effectiveness, or the discount rate to take on their worst-case values, individually. For simultaneous variation of variables, fluoridation was cost saving for all but very small communities. There, fluoridation was cost saving if the reduction in carious surfaces attributable to one year of fluoridation was at least 0.046. CONCLUSION: On the basis of the most current data available on the effectiveness and cost of fluoridation, caries increment, and the cost and longevity of dental restorations, we find that water fluoridation offers significant cost savings.     

Effectiveness of School Water Fluoridation and Dietary Fluoride Supplements in School-aged Children

School water fluoridation and school-based fluoride tablet programs both have been shown in many studies to be effective in preventing dental caries. These studies indicate that school water fluoridation reduces dental decay by approximately 40 percent and school-based fluoride tablet programs by about 30 percent. However, nearly all the studies were done when the prevalence of caries among US schoolchildren was greater than it is today, which makes it difficult to assess their current effectiveness. Data from dental surveys of school-aged children conducted during the past 30 years indicate that overall caries prevalence has declined by more than 75 percent and that of approximal tooth surfaces by more than 90 percent. Recent national data indicate the difference in caries prevalence between children with lifetime residence in either fluoridated or nonfluoridated areas has also diminished, which raises questions about the cost effectiveness of initiating school-based fluoride programs for all areas. There are still groups of children, however, seriously affected by dental caries. It is safe to assume that implementation of school water fluoridation or fluoride tablet programs will result in traditionally reported benefits among these children. Ongoing school-based fluoride programs should not be discontinued until it is known what impact their cessation will have on dental disease.     

Community water fluoridation and caries prevention: a critical review

The aim of this paper was to critically review the current role of community water fluoridation in preventing dental caries. Original articles and reviews published in English language from January 2001 to June 2006 were selected through MEDLINE database. Other sources were taken from the references of the selected papers. For the past 50 years community water fluoridation has been considered the milestone of caries prevention and as one of the major public health measures of the 20th century. However, it is now accepted that the primary cariostatic action of fluoride occurs after tooth eruption. Moreover, the caries reduction directly attributable to water fluoridation have declined in the last decades as the use of topical fluoride had become more widespread, whereas enamel fluorosis has been reported as an emerging problem in fluoridated areas. Several studies conducted in fluoridated and nonfluoridated communities suggested that this method of delivering fluoride may be unnecessary for caries prevention, particularly in the industrialized countries where the caries level has became low. Although water fluoridation may still be a relevant public health measure in poor and disadvantaged populations, the use of topical fluoride offers an optimal opportunity to prevent caries among people living in both industrialized and developing countries.     

Fluoridation and social equity

The overall reduction in caries prevalence and severity in the United States over recent decades is largely due to widespread exposure to fluoride, most notably from the fluoridation of drinking waters. Despite this overall reduction, however, caries distribution today remains skewed, with the poor and deprived carrying a disproportionate share of the disease burden. Dental caries, like many other diseases, is directly related to low socioeconomic status (SES). In some communities, however, caries experience has now diminished to the point where the need for continuing water fluoridation is being questioned. This paper argues that water fluoridation is still needed because it is the most effective and practical method of reducing the SES-based disparities in the burden of dental caries. There is no practical alternative to water fluoridation for reducing these disparities in the United States. For example, a school dental service, like those in many other high-income countries, would require the allocation of substantial public resources, and as such is not likely to occur soon. But studies in the United States, Britain, Australia, and New Zealand have demonstrated that fluoridation not only reduces the overall prevalence and severity of caries, but also reduces the disparities between SES groups. Water fluoridation has been named as one of the 10 major public health achievements of the 20th century by the Centers for Disease Control and Prevention, and promoting it is a Healthy People objective for the year 2010. Within the social context of the United States, water fluoridation is probably the most significant step we can take toward reducing the disparities in dental caries. It therefore should remain as a public health priority.     

What we know and do not know about fluoride

There is much that we know about fluoride as it relates to human health in general and dental health in particular. Some of the information that is known concerning water fluoridation and dental fluorosis is listed. What we do not know about fluoride is discussed in more detail, namely the efficacy of lower levels of fluoride in drinking water, the effect of discontinuing fluoride in drinking water in the absence of additional preventive measures, the prevalence of fluorosis and whether or not this presents a cosmetic problem. Other issues discussed include the actual amount of fluoride ingested from all sources, whether low‐fluoride dentifrices are as efficacious as conventional dentifrices in caries protection and reducing enamel fluorosis, the role of socioeconomic factors in determining caries prevalence, and the effects of bottled water use on caries prevalence in fluoridated communities.     

A Half-century of Community Water Fluoridation in the United States: Review and Commentary

The nearly 50-year history of community water fluoridation is reviewed with the major emphasis on the benefits and safety of fluoridation. Other aspects of water fluoridation also described include the apparent reduction in measurable fluoridation benefits because of the abundance of other fluoride sources, the diffusion of fluoridation effects into fluoride-deficient communities, preemptive and posteruptive effects, technical and cost aspects, sociopolitical and legal issues that affect the successful fluoridation of communities, and alternatives to community water fluoridation. The majority of studies have evaluated the effectiveness of water fluoridation on the permanent teeth of children, while there are fewer studies on deciduous teeth and in adults; the relationship between fluoride ingestion and bone health needs further clarification; the sociopolitical issues of fluoridation need to be better understood.     

Caries prevalence in a rural Chilean community after cessation of a powdered milk fluoridation program

OBJECTIVE: The milk fluoridation scheme established in Codegua, Chile, between 1994 and 1999 demonstrated the effectiveness of powdered milk as a community-based vehicle for fluoride to prevent dental caries. The present study aimed to compare caries prevalence in both the Codeguan control and test communities, three years after ending fluoride distribution through the powdered milk fluoridation scheme, to assess whether the benefits of such milk fluoridation were still present in the test community. METHODS: Children 3-6 years old living in Codegua (test community) and La Punta (control community) were examined for dental caries at their educational facilities by three trained and calibrated examiners using natural light, dental mirrors, and sickle probes. Differences in caries prevalence (dmfs) by year of the study were tested for statistically significant differences using the Mann-Whitney U test. RESULTS: Findings from Codegua (1999-2002) indicate that the dental caries experience increased in all age groups following the termination of powdered milk fluoridation. These differences reached levels of statistical significance in the 3-, 4-, and 5- year old group (P < .03). Comparing results from Codegua and La Punta (2002), no statistically significant differences were found. CONCLUSIONS: Termination of the powdered milk fluoridation scheme resulted in a deterioration of the dental health of children. After three years, dental caries prevalence was higher than that reached at the end of the scheme and equivalent to that of the control community without fluoride exposure. These results emphasize the need to establish and maintain an alternative mechanism of community-based fluoridation of proven effectiveness for the prevention of dental caries in communities where water fluoridation is not available.     

Maintenance of optimal fluoride levels in public water systems

OBJECTIVE: This study examines the quality of water fluoridation in public water supplies. METHODS: An assessment of daily fluoride levels among all communities that fluoridate their public water supplies in New Hampshire was conducted from January 1, 2000, through June 30, 2002. Results were compared against recommendations from the Centers for Disease Control and Prevention. RESULTS: The fluoride concentration was less than the recommended minimum value on 42.0 percent of days, within the accepted control range on 49.8 percent of days, and above the recommended maximum value on 1.0 percent of days. On 7.1 percent of days, a fluoride concentration was not determined. Only 2 (18.2%) of 11 public water supplies maintained the fluoride concentration in the optimal range > or =80 percent of the days. CONCLUSIONS: For public water supplies in New Hampshire that fluoridate, suboptimal levels are the most common problem. Water systems need to better maintain recommended fluoride levels if communities are to realize the full benefits of fluoridation.     

Water Fluoridation Results in Basel since 1962: Health and Political Implications

The population of the canton Basel-City has been provided with fluoridated water since May 1962. This paper presents a summary of basic findings from evaluations of this public health intervention. Standard methods were used for assessing dental caries, enamel fluorosis, urinary fluoride, and other data. Caries prevalence of schoolchildren declined until 1977 because of water fluoridation, after which it continued to decline until the late 1980s due to reasons other than water fluoridation. Caries prevalence in Basel was at least as low as in those other parts of Switzerland where either school-based dental health education programs or comprehensive salt fluoridation programs had been implemented for many years. Enamel fluorosis was seen in 38 percent of the children, similar to regions with comprehensive salt fluoridation, but higher than in low-fluoride regions. Overlap of salt and water fluoridation in families consuming both fluoridated water and fluoridated salt has occurred, but has not resulted in problems. Fluoride concentrations (close to, but mostly below 1.0 ppm) and excretions (0.45–0.80 mg Fper day in children, around 1 mg in adults) corresponded to expected levels. Statistics from both the School Dental Service and the Public Dental Clinic indicate a dramatic reduction in the amount of conservation dentistry being done and, in adults, prosthetic services. Political steps to remove water fluoridation were taken in 1976, 1982, 1989, and 1993, but have not been successful. Water fluoridation has resulted in the expected benefit and continues to exist beside salt fluoridation used in the other cantons of Switzerland.     

Caries in primary dentition and social class in high and low fluoride areas

Abstract Of the two random samples studied, the first represented 6–8-year-old residents of a natural high fluoride area (n= 115) and residents of all other areas of Finland (n= 1219). The second sample was representative for 7–9-year-old children participating in public dental care in an area with artificially fluoridated pipe water (n= 182) and areas with low fluoride (n = 530) in one Finnish county. Structured questionnaires were used to collect data on social class; caries diagnoses were made by local dentists in municipal dental clinics. Children in the highest social class had the lowest caries experience in both high and low fluoride areas. Differences between middle and lower social class children were small. Fluoride affected caries in the primary dentition similarly in all social classes; in both samples this was shown statistically by non significant interaction between social class and fluoride. In Finland, differences between social classes in caries in the primary dentition cannot be removed solely by implementing water fluoridation.     

A re-examination of the pre-eruptive and post-eruptive mechanism of the anti-caries effects of fluoride: is there any anti-caries benefit from swallowing fluoride?

The belief that fluoridated water reduces caries incidence by half stems from years of fluoridation studies where the caries rates of people in various fluoridated and non-fluoridated communities were compared. By their nature, the water fluoridation trials were not able to distinguish between the topical effects of the fluoride in the water and the systemic effects of the fluoride that is inevitably swallowed and incorporated into developing teeth. Some attempts have been made to estimate the contribution of systemic fluoride to the control of dental caries but researchers are discovering that the topical effects of fluoride are likely to mask any benefits that ingesting fluoride might have. In this updated review of the pre-eruptive vs. post-eruptive benefits of fluoride in the prevention of dental caries, a re-examination of the literature, which is often cited to support the notion that swallowing fluoride, either in water or in pill form, was done in recognition of the mounting evidence for the topical mechanism as being the primary mechanism for the prevention of dental caries. Maximum benefits from exposing newly erupted teeth to topical fluoride in the oral cavity may have been seriously under-estimated. This has obvious implications for the use of systemic fluorides to prevent dental caries and forces everyone working in the field to examine more closely the risks and benefits of fluoride in all its delivery forms.     

The Pre-and Posteruptive Effects of Fluoride in the Caries Decline

The widespread availability of fluoride from many sources is accepted as a major reason for the caries decline among children in developed countries. There is still controversy, however, about its principal mode of action. This article reviews the evidence on fluoride's preeruptive and posteruptive effects, and suggests reasons for its continuing role in the caries decline. Early fluoridation studies accepted that fluoride acted preruptively through incorporation into developing enamel; but further research could not explain why fluoride levels were not clearly higher in enamel exposed to fluoride, nor why there were no clear correlations between caries experience and enamel fluoride concentration. Instead, considerable evidence suggests that fluoride acts mainly, though not entirely, through posteruptive remineralization of demineralized enamel. Caries experience has declined in nonfluoridated as well as in fluoridated areas, though DMF scores are still consistently lower in fluoridated areas. Posteruptive remineralization effects are seen from fluoridated drinking water as well as with fluoride from other sources. The continuing caries decline, beyond the level suggested by early fluoridation field trials, can be attributed either to more efficient remineralization or to long-term, intraoral ecological change, or to both.     

A model to determine the economic viability of water fluoridation

Objectives: In view of concerns expressed by South African local authorities the aim of this study was to develop a model to determine whether water fluoridation is economically viable to reduce dental caries in South Africa. Methods: Microsoft Excel software was used to develop a model to determine economic viability of water fluoridation for 17 water providers from all nine South African provinces. Input variables for this model relate to chemical cost, labor cost, maintenance cost of infrastructure, opportunity cost, and capital depreciation. The following output variables were calculated to evaluate the cost of water fluoridation: per capita cost per year, cost‐effectiveness and cost‐benefit. In this model it is assumed that the introduction of community water fluoridation can reduce caries prevalence by an additional 15 percent and that the savings in cost of treatment will be equal to the average fee for a two surface restoration. Results: Water providers included in the study serve 53.5 percent of the total population of South Africa. For all providers combined chemical cost contributes 64.5 percent to the total cost, per capita cost per year was $0.36, cost‐effectiveness was calculated as $11.41 and cost‐benefit of the implementation of water fluoridation was 0.34. Conclusions: This model confirmed that water fluoridation is an economically viable option to prevent dental caries in South African communities, as well as conclusions over the last 10 years that water fluoridation leads to significant cost savings and remains a cost‐effective measure for reducing dental caries, even when the caries‐preventive effectiveness is modest.     

High resolution mapping of reticulated water fluoride in Western Australia: opportunities to improve oral health

Background: Drinking water with an optimum fluoride concentration is a recognized effective method to reduce dental decay. Methods: In this study normal suppliers of drinking water in Western Australia provided map data regarding the distribution of their supplies and the locations of their test points. These data were collated into a single unified map of Western Australian water supplies and fluoride levels. It is clear that the effect of prevention in regionally isolated communities is significant as the cost of providing service is anywhere between 2 and 4 times higher than that in high density regions. Results: The current study found that although a very significant proportion of the population has access to water with fluoride concentrations that would be caries protective, most of these are large urban centre based. Conclusions: Those with high burdens of dental disease are mostly residential in rural and remote areas where water is either not fluoridated, nor regulated, or low in fluoride. However, it is acknowledged that water fluoridation, for many reasons, is not always feasible in rural and remote communities, and preventive efforts through alternative sources of fluoride (e.g. toothpaste) should be considered, even if less effective at community level.     

Fluoride content of still bottled water in Australia

BACKGROUND: Recently there has been a considerable increase in the consumption of bottled water in Australia. Overseas studies have found the fluoride levels in many bottled waters are well below levels considered optimal for preventing dental caries. This raises the concern that if bottled water is regularly consumed an effective means of preventing dental caries is unavailable. The aim of this study was to determine the fluoride concentration in 10 popular brands of still bottled water currently sold in Australia. METHODS: The fluoride content of water samples were determined using an ion analyser and compared to a fluoride standard. RESULTS: The fluoride concentration of all bottled waters was less than 0.08 ppm. Only three of the 10 brands indicated the fluoride content on their labels. Melbourne reticulated water was found to be fluoridated at 1.02 ppm. CONCLUSIONS: All bottled waters tested contained negligible fluoride which justifies the concern that regular consumption of bottled water may reduce the benefits gained from water fluoridation. It is recommended that all bottled water companies should consider stating their fluoride content on their labels. This will inform consumers and dental care providers of the levels of fluoride in bottled water and allow an informed decision regarding consumption of fluoridated versus non-fluoridated drinking water.     

Caries in the primary dentition, after discontinuation of water fluoridation, among children receiving comprehensive dental care

Abstract – The city of Kuopio in central Finland had fluoridated piped water for 33 years, beginning in 1959. Due to strong opposition by various civic groups, water fluoridation was stopped at the end of 1992. There is little information on the consequences of stopping fluoridation in a community with comprehensive dental care for all children and adolescents, who are frequently exposed to different fluoride measures both at home and in the dental office. Objectives: The aim of this repeated cross‐sectional survey was to examine how discontinuation of water fluoridation in Kuopio affected caries in the primary dentition. Changes in the mean dmfs values between 1992 and 1995 in Kuopio were compared to those in Jyväskylä, a low‐fluoride community that has repeatedly been used as the reference area for Kuopio. Methods: In 1992 and 1995, independent random samples of all children aged 3, 6 and 9 years were drawn in Kuopio and Jyväskylä. The total number of subjects examined was 421 in 1992 and 894 in 1995. Calibrated dentists registered caries clinically and radiographically. Results: In all age groups both in 1992 and 1995, the point estimates for mean dmfs values were lower in the non‐fluoridated town. In both towns, the observed mean dmfs values were smaller in 1995 than in 1992. Conclusion: Despite discontinuation of water fluoridation, no increase of caries frequency in primary teeth was observed in Kuopio within a three‐year period.