THE EFFECT OF HYDROXYPATITE FROM CATIN FISH BONE (PANGASIUS HYPOPHTHALMUS) ON EMAIL HARDNESS OF PRIMARY TOOTH Ayu Rahma Sari Department of Dentistry Faculty of Medical of Sriwijaya University Abstract Background: Demineralization is a process of hydroxyapatite crystals consisting of calcium and phosphate ions on the surface of tooth enamel. Demineralization can be done by restoring mineral comp…