Which ion, often incorporated into water supply systems for its beneficial role on dental health?

Fluoride

The addition of fluoride to drinking water is a public health measure initiated in the mid-20th century to prevent dental cavities. Fluoride helps to strengthen tooth enamel, making teeth more resistant to the acid produced by bacteria in the mouth. This practice has significantly reduced the prevalence of cavities in populations with fluoridated water, without harmful side effects when used at recommended concentrations. Water fluoridation is considered by the CDC (Centers for Disease Control and Prevention) as one of the ten greatest public health achievements of the 20th century, demonstrating the positive impact of chemistry on collective health.