Which chemical is commonly added to drinking water to prevent dental decay?

Fluoride is commonly added to drinking water as a public health measure to prevent dental decay. It works by aiding in the remineralization of tooth enamel, making it more resistant to acid attacks from decay-causing bacteria. Additionally, fluoride can help to reverse early signs of tooth decay and reduce the ability of bacteria to produce acids that harm teeth.

In many communities, water fluoridation has been recognized as an effective way to improve dental health on a population level. Public health organizations, including the Centers for Disease Control and Prevention, endorse water fluoridation as a safe and effective method to reduce cavities and enhance oral health among children and adults alike.

Chlorine, while important in water treatment for disinfection purposes, does not have a protective effect on dental health. Sodium hydroxide is typically used to control the pH levels in water and does not offer any benefits related to dental decay. Calcium carbonate is often used to adjust water hardness and can provide some benefits to dental health indirectly, but it does not specifically prevent decay like fluoride does. Therefore, the consistent association of fluoride with enhanced dental health underscores why it is the correct choice for this question.