Fluoride Action Network



We examined the effect of fluoridation cessation on children’s dental caries experience in the Canadian cities of Calgary (cessation in 2011) and Edmonton (still fluoridated).


We used a pre-post cross-sectional design with comparison group. We studied Grade 2 schoolchildren (approximately 7 years old) 7-8 years after fluoridation cessation in Calgary, thus capturing children born after cessation occurred. Data collection included a dental examination conducted in school by calibrated dental hygienists, a questionnaire completed by parents, and fingernail clippings for a small subsample. Our overall analytic approach was twofold. We first examined differences in dental caries experience (deft and DMFT, and smooth surface caries based on defs and DMFS) between Calgary and Edmonton and over time (comparing 2018/2019 data to pre-cessation and early post-cessation surveys in our setting). Second, we evaluated whether differences were likely to reflect fluoridation cessation in Calgary, rather than other factors.


The prevalence of caries in the primary dentition was significantly higher (P < .05) in Calgary (fluoridation cessation) than in Edmonton (still fluoridated). For example, crude deft prevalence in 2018/2019 was 64.8% (95% CI 62.3-67.3), n = 2649 in Calgary and 55.1% (95% CI 52.3-57.8), n = 2600 in Edmonton. These differences were consistent and robust: they persisted with adjustment for potential confounders and in the subset of respondents who were lifelong residents and reported usually drinking tap water; they had widened over time since cessation; and they were corroborated by assessments of dental fluorosis and estimates of total fluoride intake from fingernail clippings. Findings for permanent teeth were less consistent, which likely reflects that 7-year-olds have not had the time to accumulate enough permanent dentition caries experience for differences to have become apparent.


Our findings are consistent with an adverse impact of fluoridation cessation on children’s dental health in Calgary and point to the need for universal, publicly funded prevention activities—including but not limited to fluoridation.

*Full-text article online at https://onlinelibrary.wiley.com/doi/epdf/10.1111/cdoe.12685

Supporting Information:

cdoe12685-sup-0001-TableS1.docxWord document, 13.8 KB, TABLE S1


This study was funded by a research grant from the Canadian Institutes of Health Research (CIHR) (PJT-156258). Dr Lindsay McLaren was supported by an Applied Public Health Chair research award funded by CIHR (Institute of Population & Public Health and Institute of Musculoskeletal Health & Arthritis), the Public Health Agency of Canada, and Alberta Innovates—Health Solutions (CIHR ID CPP-137907). Dr Cynthia Weijs was supported by a CIHR Health System Impact Fellowship, 2017-2020 (Award # 403867). We are grateful to Dr Marília Afonso Rabelo Buzalaf, Professor of Biochemistry and Cariology at the University of São Paulo, for performing the analysis of fluoride concentrations from fingernail samples. We also extend our sincere thanks to the dental hygienists and clerks who worked on the project, and to the participating school boards, schools, and families.


1.Burt BA, Eklund SA Dentistry, Dental Practice, and the Community, 5th edn. Philadelphia, PA: W.B. Saunders; 1999. Google Scholar

2. Rose G. Sick individuals and sick populations. Int J Epidemiol. 2001; 30(3): 427432. Crossref CAS PubMed Web of Science®Google Scholar

3. Ast DB, Finn SB, McCaffrey I. The Newburgh-Kingston caries fluorine study: Dental findings after three years of water fluoridation. Am J Public Health Nations Health. 1950; 40(6): 716724. Crossref CAS PubMed Google Scholar

4. Brown HK, McLaren HR, Josie GH, Stewart BJ. The Brantford-Sarnia-Stratford fluoridation caries study 1955 report. Can J Public Health. 1956; 47: 149159. CAS PubMed Google Scholar

5. Iheozor-Ejiofor Z, Worthington HV, Walsh T, et al. Water fluoridation for the prevention of dental caries. Cochrane Database Syst Rev. 2015; 6: CD010856. https://doi.org/10.1002/14651858.CD010856.pub2 Google Scholar

6. Rugg-Gunn AJ, Spencer AJ, Whelton HP, et al. Critique of the review of ‘Water fluoridation for the prevention of dental caries’ published by the Cochrane Collaboration in 2015. Br J Dent. 2016; 220(7): 335340. Crossref CAS PubMed Web of Science®Google Scholar

7. Canadian Agency for Drugs and Technologies in Health (CADTH). Community Water Fluoridation Programs: A Health Technology Assessment—Review of Dental Caries and Other Health Outcomes. Ottawa: CADTH; 2019. https://www.cadth.ca/community-water-fluoridation-programs-health-technology-assessment

8. Featherstone JDB. Prevention and reversal of dental caries: Role of low level fluoride. Community Dent Oral Epidemiol. 1999; 27: 3140. PubMed

9. Groeneveld A, Van Eck AA, Backer DO. Fluoride in caries prevention: Is the effect pre- or post-eruptive? J Dent Res. 1990; 69: 751755. Crossref PubMed Google Scholar

10.  Public Health Agency of Canada (PHAC). The State of Community Water Fluoridation across Canada, 2017 Report. Prepared by the Public Health Capacity and Knowledge Management Unit, Quebec Region for the Office of the Chief Dental Officer of Canada. PHAC. https://www.canada.ca/en/services/health/publications/healthy-living/community-water-fluoridation-across-canada-2017.html

11. O’Neill B, Kapoor T, McLaren L. Politics, science, and termination: A case study of water fluoridation policy in Calgary in 2011. Rev Policy Res. 2018; 36(1): 99120. Wiley Online Library Web of Science®Google Scholar

12. McLaren L, Singhal S. Does cessation of community water fluoridation lead to an increase in tooth decay? A systematic review. J Epidemiol Community Health. 2016; 70: 934940. PubMed

13. Meyer J, Margaritis V, Mendelsohn A. Consequences of community water fluoridation cessation for medicaid-eligible children and adolescents in Juneau, Alaska. BMC Oral Health. 2018; 215. https://doi.org/10.1186/s12903-018-0684-2

14. Canadian Academy of Health Sciences (CAHS). Improving Access to Oral Health Care for Vulnerable People Living in Canada. Ottawa: CAHS; 2014. https://cahs-acss.ca/wp-content/uploads/2015/07/Access_to_Oral_Care_FINAL_REPORT_EN.pdf

15, Health Canada. Report on the Findings of the Oral Health Component of the Canadian Health Measures Survey, 2007-2009. Ottawa, ON: Minister of Health; 2010. Google Scholar

16. Quiñonez C. Dentistry in Alberta: Time for a Checkup?. Edmonton, AB: Parkland Institute; 2020. https://www.parklandinstitute.ca/dentistry_in_alberta_media

17. Flanagan G. From gap to chasm: Alberta’s increasing income inequality. Edmonton, AB: Parkland Institute; 2015. https://www.parklandinstitute.ca/from_gap_to_chasm

18.Shi C, Faris P, McNeil DA, et al. Ethnic disparities in children’s oral health: Findings from a population-based survey of grade 1 and 2 schoolchildren in Alberta, Canada. BMC Oral Health. 2018; 18: 1. https://doi.org/10.1186/s12903-017-0444-8

19. Shi C, Aparicio-Ting F, Faris P, Patterson S, McLaren L. Small area contextual effects on children’s dental caries in Alberta: A multilevel analysis. Can J Public Health. 2021; 112: 773781. PubMed

20. McLaren L, Patterson S, Thawer S, et al. Measuring the short- term impact of fluoridation cessation on dental caries in grade 2 children using tooth surface indices. Community Dent Oral Epidemiol. 2016; 44(3): 274282. PubMed

21. McLaren L, Patterson S, Thawer S, et al. Exploring the short- term impact of community water fluoridation cessation on children’s dental caries: A natural experiment in Alberta. Canada. Public Health (Elsevier). 2017; 146: 5664. PubMed

22. Edelstein BL. The dental caries pandemic and disparities problem. BMC Oral Health. 2006; 6(Suppl 1): S2. PubMed

23. McLaren L, McNeil D, Potestio M, et al. Equity in children’s dental caries before and after cessation of community water fluoridation: differential impact by dental insurance status and geographic material deprivation. Int J Equity Health. 2016; 15: 24. PubMed

24. Singhal S, Farmer J, McLaren L. Methodological considerations for designing a community water fluoridation cessation study. Community Dent Oral Epidemiol. 2017; 45(3): 193200. PubMed

25. Cho H-J, Jin B-H, Park D-Y, et al. Systemic effect of water fluoridation on dental caries prevalence. Community Dent Oral Epidemiol. 2014; 42(4): 341348. PubMed

26. Singh KAA, Spencer J, Armfield JM. Relative effects of pre-and posteruption water fluoride on caries experience of permanent first molars. J Public Health Dent. 2003; 63(1): 1119. PubMed

27.  Statistics Canada. Focus on Geography Series, 2016 Census. https://www12.statcan.gc.ca/census-recensement/2016/as-sa/fogs-spg/select-Geo-Choix.cfm?Lang=Eng&GK=CSD&TOPIC=1

28.  Statistics Canada. Census Profile, 2016 Census. https://www12.statcan.gc.ca/census-recensement/2016/dp-pd/prof/search-recherche/lst/results-resultats.cfm?Lang=E&TABID=1&G=1&Geo1=&Code1=&Geo2=&Code2=&GEOCODE=48&type=029. Government of Alberta. Student Population Statistics. https://www.alberta.ca/student-population-statistics.aspx

31. Little RJA, Rubin DB. Statistical Analysis with Missing Data. New York: John Wiley & Sons; 1987. Google Scholar

32. Centers for Disease Control and Prevention. Division of Oral Health. Oral Health Data Tools. Atlanta, Georgia: CDC. https://www.cdc.gov/oralhealth/data-tools/index.htm

33.  Statistics Canada. Canadian Health Measures Survey, Cycle 1. Ottawa: Statistics Canada. https://www23.statcan.gc.ca/imdb-bmdi/document/5071_D2_T1_V1-eng.htm

34. Warren JJ, Levy SA, Kanellis MJ. Dental caries in the primary dentition: Assessing prevalence of cavitated and noncavitated lesions. J Public Health Dent. 2002; 62(2): 109141. PubMed

35. World Health Organization (WHO). Oral Health Surveys: Basic Methods, 5th edn. Geneva: World Health Organization; 2013. Google Scholar

36. Rozier RG. Epidemiologic indices for measuring the clinical manifestations of dental fluorosis: overview and critique. Adv Dent Res. 1994; 8(1): 3955. PubMed

37. Pessan JP, Buzalaf MAR. Historical and recent biological markers of exposure to fluoride. Monogr Oral Sci. 2011; 22: 5265. PubMed

38. Whitford GM, Sampaio FC, Arneberg P, von der Fehr FR. Fingernail fluoride: A method for monitoring fluoride exposure. Caries Res. 1999; 33: 462467. PubMed

39.  StataCorp. Stata Statistical Software: Release 16. College Station, TX: StataCorp LLC; 2019. Google Scholar

40. Dimick JB, Ryan AM. Methods for evaluating changes in health care policy: The difference-in-differences approach. JAMA. 2014; 312(22): 24012402. PubMed

41. Thawer S, Shi C, Weijs C, McLaren L. Exploring reported dental hygiene practice adaptations in response to water fluoridation status. Can J Dent Hyg. 2018; 52(2): 110121. Google Scholar

42. Groenveld A. Longitudinal study of prevalence of enamel lesions in a fluoridated and non-fluoridated area. Comm Dent Oral Epid. 1985; 13(3): 159163. PubMed

43. Lynch RJM. The primary and mixed dentition, post-eruptive enamel maturation and dental caries: A review. Int J Dent J. 2013; 63: 313. PubMed

44. Canadian Institute for Health Information (CIHI). Treatment of Preventable Dental Cavities in Preschoolers: A Focus on Day Surgery Under General Anesthesia. Ottawa: CIHI; 2013. https://publications.gc.ca/site/eng/9.698831/publication.html?wbdisable=true

45. Alberta Health Services (AHS). Oral Health Action Plan. AHS Provincial Oral Health Office, Healthy Public Policy Unit. 2016. https://www.albertahealthservices.ca/assets/info/oh/if-oh-action-plan.pdf

46. Rowan-Legg A. Oral Care for Children—A Call for Action. Canadian Paediatric Society. 2018. https://www.cps.ca/en/documents/position/oral-health-care-for-children

47. Horowitz HS. Indexes for measuring dental fluorosis. J Public Health Dent. 1986; 46(4): 179183. PubMed

48. Revelo-Mejía IA, Hardisson A, Rubio C, Gutiérrez AJ, Paz S. Dental fluorosis: the risk of misdiagnosis—A review. Biol Trace Elem Res. 2021; 199(5): 17621770. PubMed

49. Centers for Disease Control and Prevention. Epi Info™ (Public Domain Software). https://www.cdc.gov/epiinfo/index.html

50. Mauriello SM, Bader JD, Disney JA, Graves RC. Examiner agreement between hygienists and dentists for caries prevalence examinations. J Pub Health Dent. 1990; 50(1): 3237. PubMed

51. McHugh ML. Interrater reliability: The kappa statistic. Biochem Med (Zagreb). 2012; 22(3): 276282. PubMed

52.Taves DR. Separation of fluoride by rapid diffusion using hexamethyldisiloxane. Talenta. 1968; 15(9): 969974. PubMed

53. Whitford GM. The Metabolism and Toxicity of Fluoride. Monographs in Oral  Science, 2nd edn. Basel: Karger; 1996. Google Scholar