Position Statement on Community Water Fluoridation
L.G. Do, J.A. Cury, P. James, P.A. Mossey, F.V. Zohoori, C.H. Fox, and M.K.S. Charles-Ayinde
The International Association for Dental Research (IADR) supports community water fluoridation as a safe and effective, evidence-based intervention for the prevention of dental caries. This public health measure has a high benefit/cost ratio and benefits deprived communities the most thus reducing health inequalities. While fluoride occurs naturally in water, levels vary depending on regions and sources of water. Fluoridation is the controlled addition of a precise amount of fluoride to community water systems to the level beneficial for dental health, without systemic health side-effects. The practice of adding fluoride to community water supplies began after Dr. H. Trendley Dean observed a dose response relationship between naturally occurring fluoride levels in water with dental fluorosis and caries in his famous 21-city study1. Community water fluoridation began in Grand Rapids, Michigan, USA in 1945 and reached 63.4% of the United States population in 20182. Globally, over 400 million people in 25 countries have access to community water fluoridation3. The 75-year history of community water fluoridation as a public health measure has been summarised in an IADR Centenary Review4.
Dental caries – the destruction of dental hard tissues – can result in pain, infection and tooth loss5. Caries is caused by acidic by-products produced from bacterial fermentation of free sugars, mainly sucrose. Dental caries is one of the most common non-communicable diseases that affects both adults and children globally6. The prevalence of dental caries remains high globally and across countries with different sociodemographic index (SDI) status7. Children with poor oral health are more likely to miss school and suffer academically8,9,10. The health and social impact of dental caries have been reported among people of all ages, from very young children to the elderly11,12,13. The economic impact of dental caries on the affected individuals and society has also been documented14. Socioeconomic inequalities in oral health at global and regional level are detrimental to improving population oral health15.
An adequate continuous exposure to fluoride provides significant protection from dental caries16,17. Community water fluoridation is the simplest way to maintain a constant low dose of fluoride in the oral cavity, through drinking fluoridated water or ingesting meals prepared with fluoridated water18,19. Numerous recent systematic reviews have found that water fluoridation is associated with a significant decrease in dental caries, mostly in children20,21,22,23,24. In the early 2000s, a review by the US Community Preventive Services Task Force (CPSTF), found that starting water fluoridation decreased caries in children aged 4-17 by 30-50% and that stopping water fluoridation increased caries by 18%24. Those results were confirmed by other systematic reviews conducted in the 2000s by UK Medical Research Council (MRC) and Australia National Health and Medical Research Council (NHMRC)22,25. A recent systematic review of 20 studies by the Cochrane Collaboration, showed that water fluoridation decreased dental caries in both primary and permanent teeth of children and increased the number of children free of decay in primary and permanent teeth, despite concerns about quality of the available evidence21, as well as methods used in the review26. A review by NHMRC ‘found that water fluoridation reduces tooth decay by 26-44% in children, teenagers and adults’23.
Community water fluoridation is a cost-effective method of delivering caries prevention to a large population51. A systematic review of the best available evidence pertaining to water fluoridation from cohort studies showed consistent evidence of a protective effect51,52. Additionally, a systematic review by the CPSTF found that water fluoridation is cost saving14. In other words, the savings from fewer dental restorations are greater than the cost of fluoridation for communities of greater than 1,000 people, and the larger the community, the greater the cost saving. Economic analyses from other countries have supported the findings27,28,29.
Community water fluoridation may also reduce oral health inequalities. Inequality in dental caries experience has been well documented in most developed economies with children and adults from lower socioeconomic status (SES) backgrounds experiencing more caries than those from high SES backgrounds and less likely to be treated for the disease30,31,32. When drinking water has an optimal fluoride concentration, fluoride can be passively delivered to community residents regardless of socioeconomic status or ability to access dental services. The York review22 concluded there was some evidence that water fluoridation reduced SES inequalities in caries levels in children, while the Cochrane review21 found insufficient evidence that fluoridation reduced inequalities. The NHMRC review23 concluded that there was limited evidence that fluoridation reduced SES inequalities and called for further high-quality research. More recent studies from different countries reported evidence that fluoridation reduced SES inequalities48. It is worth noting that a fundamental inequality surrounds the variability in water sources and water supply infrastructure, in that there are large parts of the world where community water fluoridation would not be possible or would be impractical because the major source of domestic and drinking water is groundwater boreholes and fluoride levels are variable and often unknown.
Community water fluoridation is a safe method of delivering fluoride at a population level. There have been numerous systematic reviews of the potential adverse health effects of water fluoridation22,23,35,36,37. None has concluded that there is a significant or consistent association between water fluoridation and the outcomes examined, including neurologic conditions, cancer or osteoporosis.
Dental fluorosis resulting in tooth discoloration is the only known adverse health effect of water fluoridation39. Teeth are only at risk of fluorosis until about age 8 during enamel formation40. The World Health Organization (WHO) recommends a concentration of 0.5 to 1.5 mg/L of fluoride to achieve caries prevention while minimizing the risk of dental fluorosis. This concentration varies depending on climate, local environment, and other sources of fluoride. Countries have decided on the concentration of water fluoride appropriate for their context. While people who drink from fluoridated water sources are at greater risk of dental fluorosis, most people who drink fluoridated water do not develop dental fluorosis23. The cases of dental fluorosis that do develop are very mild. These changes, not usually visible to the naked eye, do not affect the function of the teeth or oral health-related quality of life41. Dental fluorosis at that level has been found diminished over time42,43. Severe cases of dental fluorosis are rare in communities serviced by community water fluoridation and are not associated with fluoridated water23.
Community water fluoridation is supported by various groups, including the WHO44, the Fédération Dentaire Internationale (FDI World Dental Federation)45, national dental and health organizations, among others. Additionally, in 1999, the CDC identified community water fluoridation as one of 10 great public health achievements of the 20th century because of its effectiveness and ability to distribute fluoride equitably and cost-effectively46. To bolster this, the CDC has recently supported the creation of new technology to meet the need of rural areas and smaller sized water systems to optimally fluoridate water utilizing a cost-effective tablet system38.
While IADR always welcomes research on water fluoridation safety and effectiveness, in the current context of fluoride availability, the balance of evidence currently shows that community water fluoridation is safe, effective and cost-saving and reduces oral health disparities. Therefore, IADR supports community water fluoridation and recommends the adjustment of fluoride concentration in community water to an optimum level according to national guidelines of each country. To facilitate optimization of water fluoride concentration, IADR also supports external independent controls to monitor the concentration of fluoride in water considering the challenges associated with optimization49,50. Comparative analysis and cost-benefit analysis are also encouraged to facilitate water fluoride concentration optimization.
IADR encourages dental health professionals to sensitize the public about the benefits of CWF to ensure sustained municipal water fluoridation. Local chapters of IADR are advised to organize seminars to educate local government policymakers about CWF and conduct Continuing Education (CE) programs to train members in dental health advocacy. Advocacy efforts should emphasize on the consistent research findings about the effectiveness of water fluoridation in preventing dental caries and counter misinformation surrounding the issue47.
L.G. Do contributed to design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript, all members of the IADR Science Information Subcommittee, contributed to conception and design, critically revised the manuscript. M.K.S. Charles-Ayinde contributed to conception, design, and interpretation, and critically revised the manuscript; C.H. Fox, contributed to conception, critically revised the manuscript. All authors gave final approval and agree to be accountable for all aspects of the work.
The members of the 2021 IADR Science Information Subcommittee were J.A. Cury, L.G. Do, P. James, P.A. Mossey, and F.V. Zohoori. The IADR Science Information Committee thanks all members of the Subcommittee for providing subject matter expertise during the drafting of the policy statement.
The authors received no financial support and declare no potential conflicts of interest with respect to the authorship and/or publication of this article.
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(Adopted 1979, Updated 1999 and 2022)