Final answer:
Demineralization is the process where calcium and phosphate are lost from the hydroxyapatite crystals in tooth enamel, often leading to the formation of dental cavities.
Step-by-step explanation:
When calcium and phosphate are lost or reduced from the hydroxyapatite crystals in enamel, the process is called demineralization. This often leads to the formation of dental caries (cavities). Acidic conditions in the mouth, caused by bacteria metabolizing sugars, result in an increased solubility of minerals in the enamel. The dissolution equilibrium of calcium hydroxyapatite in enamel is represented by the equation:
Ca5(PO4)3OH(s) = 5Ca2+(aq) + 3PO43-(aq) + OH-(aq)
The breakdown of this sparingly soluble ionic compound leads to the weakening of enamel. This loss of strength in enamel is due to the hydroxyapatite crystals giving way to an influx of hydrogen ions that displace the minerals, primarily calcium and phosphate that are integral to the enamel's structure.