Final answer:
Community water fluoridation was first introduced in Grand Rapids, MI in the year 1945, providing a significant public health benefit by reducing tooth decay.
Step-by-step explanation:
Community water fluoridation, a method of preventing tooth decay, was first introduced in Grand Rapids, Michigan in the year 1945. This practice of adjusting the fluoride content in drinking water to an optimal level has been a significant public health advancement, recognized for its cost-effectiveness and wide-reaching benefits. Over the years, community water fluoridation has been complemented by other fluoride-containing products such as toothpaste, which also contribute to oral health.