Policymakers at both state and local levels often hear claims that community water fluoridation is unnecessary, asserting that fluoride toothpaste alone can sufficiently protect against dental decay. Statements like, “If more adults and children used fluoride toothpaste, there would be no need for fluoridation,” frequently arise in discussions surrounding water fluoridation.
In the early 2010s, city councils in Calgary and Windsor, two major Canadian cities, acted on this belief and decided to halt their fluoridation programs. Unfortunately, this led to a noticeable increase in tooth decay in both municipalities. A comprehensive seven-year study conducted in Calgary identified a significant rise in childhood dental decay. In Windsor, the urgent need for dental treatments among children surged by an alarming 51% following the cessation of fluoridation.
The reliance on toothpaste alone proved inadequate in preventing the rise of tooth decay in the absence of fluoridated tap water. Acknowledging the deteriorating oral health of their residents, local leaders recognized the mistake of their earlier decision and voted to restore fluoridation—Calgary reinstated it in 2018, followed by Windsor in 2025.
Why was fluoride toothpaste insufficient for adequate dental health? A recent study conducted among adults on the Island of Ireland sheds light on this issue. The research compared the incidence of cavities among individuals residing in various regions of the Republic of Ireland (ROI), where community water fluoridation is mandatory and benefits over 70% of the population, to those in Northern Ireland (NI), which lacks a fluoridation program.
The findings revealed that adults living in the fluoridated areas of the ROI experienced significantly lower rates of tooth decay compared to their counterparts in unfluoridated regions of NI. Overall, adults in the ROI showed reduced decay rates. The most striking difference was observed in the approximal surfaces of teeth, which are the narrow gaps between teeth prone to plaque buildup and subsequent decay. In adults with access to fluoridated water, decay on these surfaces was nearly 19% lower, leading researchers to conclude, “These findings support an association between long-term community water fluoridation exposure and reduced dental caries experience in adulthood.”
There is no evidence suggesting that brushing and flossing habits differ significantly between residents of the ROI and NI. this new study indicates that water fluoridation may provide an additional protective layer that helps reduce the risk of adult tooth decay, particularly in vulnerable areas like approximal surfaces.