A recent report in Science News indicates that many factors can cause tooth decay in children, from diet to genetics. But when a dentist in Calgary, Canada, started seeing an uptick in young patients with serious oral problems, he suspected a different root cause: The city stopped adding fluoride to its drinking water in 2011. 

Juneau, Alaska, did the same thing in 2007, and tooth decay there also saw an upswing. Scientific data show that Calgary and Juneau offer cautionary tales for communities seeking to end fluoridation. 

TERESA DeLORENZO

Astoria