Science Policy

Position Statement on Community Water Fluoridation

Published on: June 16, 2022

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. 
      
Author Contributions 
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. 
 
Acknowledgements  
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. 
 
References 

  1. Dean, H. 1946. Epidemiological Studies in the United States in Dental Caries and Fluorine. Science Press, American Association for the Advancement of Science: Lancaster. 
  2. Centers for Disease Control. 2021. Water Fluoridation Basics. [accessed 19 February 2021]. https://www.cdc.gov/fluoridation/basics/index.htm  
  3. The British Fluoridation Society. 2019. One in a Million. [accessed 19 February 2021]; https://bfsweb.org/. 
  4. Whelton HP, Spencer AJ, Do LG, Rugg-Gunn AJ. 2019. Fluoride Revolution and Dental Caries: Evolution of Policies for Global Use. Journal of Dental Research. 98(8): p. 837-846. 
  5. Pitts NB, Zaro DT, Marsh PH, Ekstrand K, Weintraub JA, Ramos-Gomez F, Tagami J, Twetman S, Tsakos G, Ismail A. 2017. Dental Caries. Nat Rev Dis Primers. 3: p. 17030. 
  6. Kassebaum NJ, Smith AGC, Bernabe E, Fleming TD, Reynolds AE, Vos T, Murray CJL, Marcenes W, GBD 2015 Oral Health Collaborators. 2017. Global, Regional, and National Prevalence, Incidence, and Disability-Adjusted Life Years for Oral Conditions for 195 Countries, 1990-2015: A Systematic Analysis for the Global Burden of Diseases, Injuries, and Risk Factors. J Dent Res. 96(4): p. 380-387. 
  7. Dye BA. 2017. The Global Burden of Oral Disease: Research and Public Health Significance. Journal of dental research. 96(4): p. 361-363. 
  8. Casamassimo PS, Thikkurissy S, Edelstein BL, Maiorini E. 2019. Beyond The Dmft: The Human and Economic Cost of Early Childhood Caries. J Am Dent Assoc. 140(6): p. 650-657. 
  9. Jackson SL, Vann Jr WF, Kotch JB, Pahel BT, Lee JY. 2011. Impact of Poor Oral Health on Children's School Attendance and Performance. Am J Public Health. 101(10): p. 1900-6. 
  10. Guarnizo-Herreño CC, Lyu W, Wehby GL. 2019. Children's Oral Health and Academic Performance: Evidence of a Persisting Relationship Over the Last Decade in the United States. J Pediatr. 209: p. 183-189.e2. 
  11. Heilmann AG. Tsakos, Watt RG. 2015. Oral Health Over the Life Course, in a Life Course Perspective on Health Trajectories and Transitions. Springer: Cham (CH). p. 39-59. 
  12. Tinanoff N, Baez RJ, Diaz Guillory C, Donly KJ, Feldens CA, McGrath C, Phantumvanit P, Pitts NB, Seoq WK, Sharkov N, Songpaisan Y, Twetman S. 2019. Early Childhood Caries Epidemiology, Aetiology, Risk Assessment, Societal Burden, Management, Education, and Policy: Global perspective. Int J Paediatr Dent. 29(3): p. 238-248. 
  13. Tonetti MS, Bottenberg P, Conrads G, Eickholz P, Heasman P, Huysmans MC, Lopez R, Madianos , Muller F, Needleman I, Nyvad B, Preshaw PM, Pretty I, Renvert S, Schwendicke F, Trombelli L, van der Putten GJ, Vanobbergen J, West N, Young A, Paris S.  2017. Dental Caries and Periodontal Diseases in the Ageing Population: Call to Action to Protect and Enhance Oral Health and WellBeing as an Essential Component of Healthy Ageing - Consensus Report of Group 4 of the Joint EFP/ORCA Workshop on the Boundaries Between Caries and Periodontal Diseases. J Clin Periodontol. 44 Suppl 18: p. S135-s144. 
  14. Ran T, Chattopadhyay SK. 2016. Economic Evaluation of Community Water Fluoridation: A Community Guide Systematic Review. Am J Prev Med. 50(6): p. 790-6. 
  15. Watt RG, Daly B, Allison P, Macpherson LMD, Venturelli R, Listl S, Weyant RJ, Mathur MR, Guarnizo-Herreno CC, Keller Celeste R, Peres MA, Kearns C, Benzian H. 2019. Ending the Neglect of Global Oral Health: Time For Radical Action. Lancet. 394(10194): p. 261-272. 
  16. Fejerskov O, Larsen MJ, Richards A, Baelum V. 1994. Dental Tissue Effects of Fluoride. Adv Dent Res. 8(1): p. 15-31. 
  17. Zohoori FV, Duckworth RM. 2020. Chapter 5: Microelements: Part II: F, Al, Mo and Co. Monogr Oral Sci. 28: p. 48-58. 
  18. Cury JA, Tenuta LM. 2008. How to Maintain a Cariostatic Fluoride Concentration in the Oral Environment. Adv Dent Res. 20(1): p. 13-6. 
  19. Lima CV, Tenuta LMA, Cury JA. 2019. Fluoride Increase in Saliva and Dental Biofilm due to a Meal Prepared with Fluoridated Water or Salt: A Crossover Clinical Study. Caries Res. 53(1): p. 41-48. 
  20. U.S. Department f Health and Human Services. 2015. U.S. Public Health Service Recommendation for Fluoride Concentration in Drinking Water for the Prevention of Dental Caries. Public Health Reports. 130(4): p. 318-331. 
  21. Iheozor-Ejiofor Z, Worthington HV, Walsh T, O'Malley L, Clarkson JE, Macey R, Alam R, Tugwell P, Welch V, Glenny AM. 2015. Water Fluoridation for the Prevention of Dental Caries. Cochrane Database Syst Rev. (6): p. Cd010856. 
  22. McDonagh MS, Whiting PF, Sutton AJ, Chestnutt I, Cooper J, Misso K, Bradley M, Treasure E, Kleijnen J. 2000. Systematic Review of Water Fluoridation. BMJ. 321(7265): p. 855-9. 
  23. National Health and Medical Research Council. 2017. Information Paper – Water Fluoridation: Dental and Other Human Health Outcomes. [accessed 19 February 2021]; www.nhmrc.gov.au/guidelines/publications/EH43  
  24. Truman BI, Gooch BF, Sulemana I, Gift HC, Horowitz AM, Evans CA, Griffin SO, Carande-Kulis VG, Task Force on Community Preventive Services. 2002. Reviews of Evidence on Interventions to Prevent Dental Caries, Oral and Pharyngeal Cancers, and Sports-Related Craniofacial Injuries. Am J Prev Med. 23(1 Suppl): p. 21-54. 
  25. Yeung CA. 2008. A Systematic Review of the Efficacy and Safety of Fluoridation. Evid Based Dent. 9(2):39-43.  
  26. Rugg-Gunn AJ, Spencer AJ, Whelton HP, Jones C, Beal JF, Castle P, Cooney PV, Johnson J, Kelly MP, Lennon MA, McGinley J, O'Mullane D, Sgan-Cohen HD, Sharma PP, Thomson WM, Woodward SM, Zusman SP. 2016. Critique of the Review of 'Water Fluoridation for the Prevention of Dental Caries' Published by The Cochrane Collaboration in 2015. Br Dent J. 220(7): p. 335-40. 
  27. Cobiac LJ, Vos T. 2012. Cost-Effectiveness of Extending the Coverage of Water Supply Fluoridation for the Prevention of Dental Caries in Australia. Community Dent Oral Epidemiol. 40(4): p. 369-76. 
  28. Mariño R, Zaror C. 2020 Economic Evaluations in Water-Fluoridation: A Scoping Review. BMC Oral Health. 20(1): p. 115. 
  29. Moore D, Poynton M, Broadbent JM, Murray Thomson W. 2017. The Costs and Benefits of Water Fluoridation in NZ. BMC Oral Health. 17(1): p. 134. 
  30. Elani HW, Harper S, Allison PJ, Bedos C, Kaufman JS. 2012. Socio-Economic Inequalities and Oral Health in Canada and the United States. J Dent Res. 91(9): p. 865-70. 
  31. Slade GD, Sanders AE. 2018. Two Decades of Persisting Income-Disparities in Dental Caries Among U.S. Children and Adolescents. J Public Health Dent. 78(3): p. 187-191. 
  32. Peres MA, Macpherson LMD, Weyant RJ, Daly B, Venturelli R, Mathur MR, Listl S, Keller Celeste R, Guarnizo-Herreno CC, Kearns C, Benzian H, Allison P, Watt RG. 2019. Oral Diseases: A Global Public Health Challenge. Lancet. 394(10194): p. 249-260. 
  33. Do L., Ha DH, Roberts-Thomson KF. 2018. Race- and Income-Related Inequalities in Oral Health in Australian Children by Fluoridation Status. J Dent Res Clin & Translat Res. DOI: 10.1177/2380084417751350. 
  34. Matsuo G, Aida J, Osaka K, Rozier RG. 2020. Effects of Community Water Fluoridation on Dental Caries Disparities in Adolescents. Int J Environ Res Public Health. 17(6). 
  35. Guth S, Huser S, Roth A, Degen D, Diel P, Edlund K, Eisenbrand G, Engel KH, Epe B, Grune T, Heinz V, Henle T, Humpf HU, Jager H, Joost HG, Kulling SE, Lampen A, Mally A, Marchan R, Marko D, Muhle E, Niitsche MA, Rohrdanz E, Stadler R, van Thriel C, Vieths S, Vogel RF, Wascher E, Watzl C, Nothlings U, Hengstler JG. 2020. Toxicity of Fluoride: Critical Evaluation of Evidence for Human Developmental Neurotoxicity in Epidemiological Studies, Animal Experiments and In Vitro Analyses. Arch Toxicol. 94(5): p. 1375-1415. 
  36. Scientific Committee on Health and Environmental Risks. 2011. Opinion on Critical Review of any New Evidence on the Hazard Profile, Health Effects, and Human Exposure to Fluoride and the Fluoridating Agents of Drinking Water. [accessed 19 February 2021]; https://ec.europa.eu/health/scientific_committees/environmental_risks/docs/scher_o_122.pdf 
  37. Aggeborn L, Öhman M. 2020. The Effects of Fluoride in Drinking Water. Journal of Political Economy. 129(2): p. 465-491. 
  38. U.S. Centers of Disease Control and Prevention. 2021. New Fluoride Technology Supports Oral Health. [accessed 25 March 2021]; https://www.cdc.gov/oralhealth/publications/features/cwftablet.html   
  39. Cury JA, Ricomini-Filho AP, Perecin Berti FL, Tabchoury CPM. 2019. Systemic Effects (Risks) of Water Fluoridation. Brazilian Dental Journal. 30: p. 421-428. 
  40. Fejerskov O, Manji F, Baelum V. 1990. The Nature and Mechanisms of Dental Fluorosis in Man. J Dent Res. 69 Spec No: p. 692-700; discussion 721. 
  41. Chankanka O, Levy SM, Warren JJ, Chalmers JM. 2010. A Literature Review of Aesthetic Perceptions of Dental Fluorosis and Relationships with Psychosocial Aspects/Oral Health-Related Quality of Life. Community Dent Oral Epidemiol. 38(2): p. 97-109. 
  42. Curtis AM, Levy SM, Cavanaugh JE, Warren JJ, Kolker JL, Weber - Gasparoni K. 2020. Decline in Dental Fluorosis Severity during Adolescence: A Cohort Study. J Dent Res. 99(4): p. 388-394. 
  43. Do L, Spencer A, Ha D. 2016. Natural History and Impact of Dental Fluorosis- A Prospective Cohort Study. Med J Aust. doi: 10.5694/mja15.00703. 
  44. Fawell J, Bailey K, Chilton J, Dahi E, Fewtrell L, Magara Y. 2006. Fluoride in Drinking-Water. ed. London: IWA Publishing. 144. 
  45. Fédération Internationale Dentaire. 1993. Policy Statement on Fluorides and Fluoridation for the Prevention of Dental Caries. Dent World. 2(3): p. 11-5, 17. 
  46. Centers of Disease Control. 1999. Ten Great Public Health Achievements -- United States, 19001999. MMWR Morb Mortal Wkly Rep. 48(12);241-243. 
  47. Melbye ML, Armfield JM. 2013. The Dentist's Role in Promoting Community Water Fluoridation: A Call To Action for Dentists and Educators. J Am Dent Assoc. 144(1):65-75. 
  48. Cho H-J, Lee H-S, Paik D-II, Bae K-H. 2014. Association of Dental Caries with Socioeconomic Status in Relation to Different Water Fluoridation Levels. Community Dent Oral Epidemiol. 42(6):536-42. 
  49. Bergamo ETP, Barbana M, Terada RSS, Cury JA, Fujimaki M. 2015. Fluoride Concentrations in the Water of Maringa, Brazil, Considering the Benefit/Risk Balance of Caries and Fluorosis. Braz Oral Res. 29(1):1-6. 
  50. Olivati FN, Rosario de Souza M, Tenuta LMA, Cury JA. 2011. Quality of Drinking Water Fluoridation of Capao Bonito, SP, Brazil, Evaluated by Operational and External Controls. Rev Odonto Cienc.26(4):285-290. 
  51. World Health Organization. (2019). Ending childhood dental caries: WHO implementation manual. Licence: CC BY-NC-SA 3.0 IGO. [accessed 25 March 2021]; https://www.who.int/publications/i/item/ending-childhood-dental-caries-who-implementation-manual 
  52. Moynihan P, Tanner LM, Holmes RD, Hillier-Brown F, Mashayekhi A, Kelly SAM, and Craig D. (2019). Systematic review of evidence pertaining to factors that modify risk of early childhood caries. JDR Clin Trans Res. 4(3):202–16. 

(Adopted 1979, Updated 1999 and 2022)