High levels of fluoride increase enamel porosity by disrupting which process during enamel maturation?

• A. Matrix proteins loss during maturation
• B. Mineral crystals formation
• C. Saliva production
• D. Enamel rods alignment

Answer: (A)

High fluoride levels cause enamel fluorosis by interfering with ameloblasts during maturation. During this stage, the enamel matrix proteins must be degraded and removed to allow mineral crystals to grow and fill the space, reducing porosity. Fluoride can inhibit the proteolytic enzymes (such as MMP-20 and KLK4) that degrade these proteins, so the organic matrix is not adequately cleared. Retained matrix and water keep spaces open, leading to increased porosity in the mature enamel. The disruption isn’t about saliva production or enamel rod alignment; it’s about the failure to remove the matrix proteins during maturation, which directly raises porosity.