**Question:** The minimum amount of fluoride that should be present in salt for effective anticaries activity in:

*A. 0.3%*
*B. 0.6%*
*C. 0.8%*
*D. 1%*

**Core Concept:** Fluoride is a well-known anticaries agent, which reduces the incidence of dental caries by incorporation into tooth structure, increasing its resistance to demineralization. Fluoride ions (F-) can either be ingested or topically applied on the teeth. When ingested, fluoride ions become incorporated into the enamel, dentin, and cementum during tooth formation, and subsequently into the existing tooth structure, leading to an increase in its resistance to demineralization.

**Why the Correct Answer is Right:** The correct answer is *C. 0.8%* because 0.8% (eight parts per million, ppm) is the minimum level of fluoride required in salt for effective anticaries activity. This concentration allows for the incorporation of fluoride ions into tooth structure during tooth formation and remineralization of existing tooth structure, thus preventing dental caries.

**Why Each Wrong Option is Incorrect:**

A. 0.3% (three parts per million): This concentration is too low, as it does not allow for significant incorporation of fluoride ions into tooth structure during formation and remineralization of existing tooth structure.

B. 0.6% (six parts per million): Although higher than Option A, this concentration is still suboptimal for effective anticaries activity.

D. 1% (one part per million): This concentration is too high and may cause fluorosis (fluoride-induced dental discoloration and/or fluoride uptake by bone, causing skeletal fluorosis).

**Clinical Pearl:** The optimal fluoride concentration for dental health lies between 0.8% and 1.23%, depending on the age of the individual and their susceptibility to fluorosis. Public Health England recommends 0.8% fluoride content in table salt for effective anticaries activity, while the World Health Organization (WHO) suggests 1.23% for optimal fluoride content in drinking water to prevent dental caries.

**Answer Explanation:** The correct answer is option C, 0.8%. This is the recommended fluoride concentration in table salt for effective anticaries activity, ensuring that the fluoride ions are incorporated into the tooth structure during its formation and remineralization of existing tooth structure. This concentration prevents dental caries while minimizing the risk of fluorosis in most individuals.