Start practicing

Public Health · single question

What is the MOST important factor determining the caries-preventive effectiveness of fluoride?

  1. A high level of systemic fluoride intake
  2. Incorporation into enamel during tooth development
  3. An increase in salivary calcium concentration alone
  4. Continuous low-level availability of fluoride ions in saliva and plaque
Show answer and explanation

Correct answer: D. Continuous low-level availability of fluoride ions in saliva and plaque

  • A. High systemic intake risks fluorosis without adding proportional protection.
  • B. Pre-eruptive incorporation into apatite produces fluorapatite but contributes far less than was once believed.
  • C. Calcium availability supports remineralisation but is not the operative mechanism of fluoride.
  • D. Correct. The modern understanding is that fluoride works predominantly TOPICALLY and POST-ERUPTIVELY. A CONSTANT low concentration of free fluoride ion in saliva and plaque fluid inhibits demineralisation at the crystal surface, promotes remineralisation with fluorapatite-like mineral, and inhibits bacterial enolase. This is why FREQUENCY of exposure beats concentration — twice-daily fluoride toothpaste outperforms occasional high-dose systemic delivery.

Practice Public Health questions Public Health study notes

More Public Health practice questions