Why is water fluoridation, which is the controlled adjustment of fluoride to public water supply, done?

To prevent tooth decay 

The correct answer is option 4. To prevent tooth decay.

Water fluoridation is primarily done to prevent tooth decay. So the answer is to prevent tooth decay

Here's why:

Fluoride is a naturally occurring mineral that has been shown to be effective in preventing tooth decay.

When fluoride comes into contact with teeth, it helps to:

Strengthen tooth enamel, making it more resistant to the acids produced by bacteria in the mouth.

Remineralize areas of early tooth decay, reversing the damage and preventing further cavities.

Inhibit the growth of bacteria that contribute to tooth decay.

Benefits of Water Fluoridation:

Public health benefit: Water fluoridation is considered a cost-effective and efficient way to deliver fluoride to the entire population, regardless of their socioeconomic status or access to dental care.

Reduction in cavities: Studies have shown that water fluoridation can significantly reduce tooth decay rates in children and adults.

Improved oral health outcomes: This translates to fewer cavities, less pain and suffering, and lower dental care costs for individuals and society as a whole.

Important to Note:

While water fluoridation is a safe and effective public health measure, there are also concerns and controversies associated with it, which are important to consider and understand through credible sources.