A new study from the University of Calgary that compares schoolchildren in Alberta found that fluoride cessation in Calgary has had a negative impact on children's dental health.

The researchers compared the dental health of Grade 2 children in both Edmonton and Calgary from the 2004/2005 and 2013/2014 school years and looked for an increase in tooth decay on the surfaces of their teeth.

“We found that dental cavities, or tooth decay actually got worse in both cities but it got more worse in Calgary where fluoridation stopped than in Edmonton,” said the study's lead author Lindsay McLaren

McLaren says that the findings suggest that there are public health benefits to fluoridation.

"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," she said.

Specifically in Calgary, the average kid developed more than five new cavities, while over the same time period their Edmonton counterparts only increased by three.

“It’s a statistically significant finding, which means that it’s unlikely to be a random or a chance finding,” said McLaren.

Researchers found that there was a worsening in the decay of baby teeth in Calgary children since fluoridation was stopped and that the number of tooth surfaces with decay per child increased by 3.8 surfaces in Calgary from 2004/2005 to 2013/2014, compared to an increase of 2.1 surfaces per child in Edmonton.

Scientists say that the average child of this age has about 20 teeth, with four or five surfaces per tooth.

The study also showed that there was a general increase in tooth decay in both Calgary and Edmonton between 2004/2005 and 2013/2014, although the increase was greater in Calgary.

Researchers say several different factors could be behind the rise in tooth decay in both cities, including: the impact of the global economic recession of 2008; shifting economic conditions in Alberta (which is primarily based on the oil and gas industry); an increase in the ethnic diversity in both of these cities over time; and an increase in the consumption of bottled water, which is not fluoridated.

Many dentists say they have seen an uptick in the amount of cavities in Calgary children since fluoride was removed from the drinking water here.

“We’re seeing much more extensive dental decay in a much younger population than we had seen when fluoride was in our water,” said Dr. Leonard Smith. “The fact that our city had chosen to remove the fluoride has been one of the most anti-public health measures ever in the City of Calgary.”

Adding fluoride to public drinking water started in the mid-1940s and is seen as a way of improving dental health at the population level. Edmonton first introduced the practice in 1967 and continues to do so, while Calgary introduced it in 1991 and stopped in 2011.

Removing fluoride from drinking water is a debate facing many communities in North America and according to the study, more than 30 communities have decided to discontinue the practice since 2005.

The study was published Wednesday in the journal Community Dentistry and Oral Epidemiology.

(With files from Kevin Green and ctvnews.ca)