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A tale of two cities finds that community water fluoridation prevents caries

Research study looks into effects of fluoride cessation in Calgary compared with fluoridated Edmonton

August 10, 2021

By David Burger

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The prevalence of caries in the primary dentition of children was significantly higher in Calgary, Canada, without fluoridated water, than in Edmonton, where the water is still fluoridated, according to a study published by the journal Community Dentistry and Oral Epidemiology.

Calgary and Edmonton are the two largest cities in the province of Alberta, with a population of about 1.2 million and 932,500, respectively. In Calgary, fluoridation began in 1991 and ceased in 2011, and fluoridation has existed in Edmonton since 1967.

“We concluded that our findings were consistent with a short-term adverse effect of fluoridation cessation on children's dental caries experience, and on social inequities in children's dental caries experience,” wrote the researchers from the Department of Community Health Science at the University of Calgary and School of Dentistry at the University of Alberta in Edmonton, among other Canadian researchers.

The researchers studied second-graders born after fluoridation cessation in Calgary. Data collection included a dental exam conducted in school by dental hygienists, a questionnaire completed by parents and fingernail clippings for a small subsample. Fingernail clippings provide assessments of dental fluorosis and estimates of total fluoride intake.

They examined differences in dental caries experience between Calgary and Edmonton over time and evaluated whether differences were likely to reflect fluoridation cessation in Calgary, rather than other factors.

The findings “point to the need for universal, publicly funded prevention activities — including, but not limited to, fluoridation,” the researchers wrote.

The research was funded by a grant from the Canadian Institutes of Health Research.

The study was an important contemporary study that adds evidence of the benefit of community water fluoridation to the many other studies of its kind, said Howard Pollick, fluoridation consultant to the California Department of Public Health, health sciences clinical professor at the University of California, San Francisco School of Dentistry and member of the ADA’s National Fluoridation Advisory Committee.

“I hope this is sufficiently convincing to the leadership in the city of Calgary, Alberta, that they see the harm that stopping fluoridation has happened to the children of their city to want to reinstate fluoridation of the water supplies,” Mr. Pollick said.

The findings mirror the results of a 2019 study in which children with Medicaid in Juneau, Alaska, without access to optimally fluoridated water had more dental caries-related procedures than youth who grew up before the Alaskan capital ceased its fluoridation program, according to research published in BMC Oral Health.

For that study, public health researchers analyzed Medicaid dental claims records of about 1,900 0- to 18-year-old patients in Juneau's main ZIP code. They compared claims from a year in which the city water was fluoridated at an optimal level for tooth decay, 2003, and from 2012, five years after the city ended its fluoridation program.

For more information on fluoride and ADA advocacy of community water fluoride, visit ADA.org/fluoride.