Tooth Enamel Demineralization: Caries and Erosion from the Viewpoint of Chemistry

The demineralization of tooth enamel is the primary consequence of dental caries, leading to cavities and finally tooth loss. Erosive tooth wear from acidic beverages and food is another factor that degrades enamel. In both cases, an acidic environment leads to etching and the final dissolution of tooth mineral, i.e., hydroxyapatite. Here, this process is discussed from a chemical perspective, taking into account the solubility of calcium phosphate and the presence of the pellicle (protein layer) and plaque (bacterial biofilms), which both affect the dissolution rate. While low pH is definitely decisive, calcium-binding ligands (e.g., acid anions, proteins) contribute to dissolution by removing calcium ions from the equilibrium. This is an important effect in the oral cavity where the concentration of biomolecules is high. The situation is complicated by the fact that the composition of saliva and the oral microbiome vary considerably between individuals. The state of current knowledge on the demineralization of enamel is summarized and discussed, also in the context of approaches to prevent dental caries and erosive tooth wear.