What evidence is provided regarding the mechanism of action of fluoride?

Fluoride's mechanism of action primarily revolves around its ability to penetrate and strengthen the enamel surface of the teeth. This process involves several key functions. First, fluoride is incorporated into the hydroxyapatite crystal structure of the enamel, transforming it into a more acid-resistant form called fluorapatite. This change enhances the enamel's resistance to demineralization caused by acids produced by bacteria in plaque, thereby helping to prevent cavities.

Additionally, fluoride actively participates in the remineralization process. When demineralization occurs, fluoride ions can intervene by attracting calcium and phosphate ions, which are essential for rebuilding and strengthening previously weakened enamel. This enhances the overall integrity of the tooth structure, making it more resilient to future decay.

In contrast, the other options do not accurately reflect the established scientific understanding of fluoride's role in dental health. Fluoride does not change the color of teeth or promote harmful bacteria; rather, it actively combats these issues by enhancing overall tooth structure. Furthermore, its effects are not confined solely to the salivary glands, but rather target the enamel directly to provide protective benefits.