In the shadow of the Rocky Mountains, a public health debate rages. It’s not about vaccines, masks or where people can smoke, though — it’s about fluoride. It’s in our toothpaste and mouthwash, and a common word around dental offices. But in Calgary, it holds a spot in the public consciousness due to decades of advocates on both sides slogging through six plebiscites on whether the city should put fluoride — a mineral found in rocks and dirt — into the water supply to fight tooth decay.