Decay Increases After Calgary Stops Fluoridation



Since the City of Calgary ceased its public water fluoridation efforts in 2011, children in second grade there now have an average of 3.8 more tooth surfaces with decay, according to the O’Brien Institute for Public Health. Second graders in Edmonton, which has been fluoridating its water since 1967, have only seen an increase of 2.1 surfaces.

“This study points to the conclusion that tooth decay has worsened following removal of fluoride from drinking water, especially in primary teeth, and it will be important to continue monitoring these trends,” said Lindsay McLaren, PhD, lead researcher of the study for the institute and associate professor in the department of community health services at the University of Calgary Cumming School of Medicine.

The researchers collected data from more than 5,000 children from randomly selected schools in Calgary and Edmonton during the 2004 to 2005 school year and 2013 to 2014 school year. They used second graders because these children typically have both baby and permanent teeth.

“The early effects of fluoridation cessation found in this study support the role of water fluoridation in contributing to improved oral health of children and that it is a public health measure worth maintaining,” said Steven Patterson, DDS, a professor at the School of Dentistry at the University of Alberta, which also participated in the study, along with Alberta Health Services.

The researchers noted that while there was an increase in primary tooth decay in both cities, the magnitude of the increase in Calgary was significantly greater than the increase in Edmonton. They also reported a non-significant trend toward an increase in decay in permanent teeth in Calgary that was not apparent in Edmonton.

“I was not at all sure that we would see these effects. It had only been about 3 years since fluoride was removed, which is on the short side,” said McLaren. “Plus, there are potentially several sources of fluoride in both environments, which would tend to reduce the observed effect of removing fluoride from the drinking water.”

The study, “Measuring the Short-Term Impact of Fluoridation Cessation on Dental Caries in Grade 2 Children Using Tooth Surface Indices,” was published by Community Dentistry and Oral Epidemiology.

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