Question

What is the primary mechanism associated with the role of fluoride in prevention of dental caries?​ a. ​Fluoride increases calcium absorption, which increases crystal formation of teeth b. ​Fluoride increases salivation which aids in the removal of bacteria and the foods needed to sustain bacterial growth c. ​Decay is reduced due to the inhibitory effects of fluoride on growth of bacteria on the teeth d. ​Fluoride becomes incorporated into the crystalline structure of teeth, making them less susceptible to decay e. ​Decay is inhibited due to neutralization of organic acids produced by bacteria on the teeth

Answer 1

d. ​Fluoride becomes incorporated into the crystalline structure of teeth, making them less susceptible to decay

Step-by-step explanation:

Dental caries results when cariogenic (caries-causing) bacteria metabolize carbohydrates or sugars present in the mouth for their energy needs, producing organic acids as byproducts, thus lowering the pH of the plaque biofilm.

The hydroxyapatite of tooth enamel is composed mainly of phosphate ions (PO₄³⁻) and calcium ions (Ca⁺). Under normal conditions, there is a stable equilibrium between the calcium and phosphate ions in saliva and the crystalline hydroxyapatite. At low pH (acidic conditions), there is a shift in equilibrium resulting in the dissolution of hydroxyapatite from tooth enamel, a process known as demineralization. A reverse process called remineralization (the process of incorporation of minerals in tooth enamel) occurs when the saliva, acting as a buffer elevates pH. When equilibrium is shifted to favor continued demineralization, dental caries results.

However, when fluoride is present in saliva, fluorapatite, rather than hydroxyapatite, forms during the remineralization process as fluoride ions replace hydroxyl groups in the formation of the apatite crystal lattice.

Fluorapatite is less soluble than hydroxyapatite making it more resistant to demineralization, even under conditions of low pH. Thus, fluoride acts as an effective anticaries agent.